ML20206N243
| ML20206N243 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1999 |
| From: | Mary Anderson, Mckenziecarter, Meck R, Otis M, Roberts J NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES), SCIENCE APPLICATIONS INTERNATIONAL CORP. (FORMERLY |
| To: | |
| References | |
| NUREG-1640, NUREG-1640-DRFT, NUREG-1640-V01-DR-FC, NUREG-1640-V1-DR-FC, NUDOCS 9905170182 | |
| Download: ML20206N243 (250) | |
Text
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$ AWAf NUREG-1640, Vol.1 Radiological Assessments for Clearance of Equipment and Materials From l ' Nuclear Facilities Main Report Draft Report for Comment I
Manuscript Completed: January 1999 Date Published: March 1999 i
Prepared by M.A. McKenzie-Carter *, M,D. Otis*, M.E. Anderson *,
J. A. Roberts *, R.L. Gotchy*, R. A. Meck j l ' Science Applications International Corporation p 545 Shoup Avenue //
l Idaho Falls, ID 83402 l Division of Regulatory Applications bel
! Omce of Nuclear Regulatory Research l U.S. Nuclear Regulatory Commission >
l Wcshington, DC 20555-0001 i
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(~'S ABSTRACT
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This report documents the technical basis for the Nuclear Regulatory Commission to use in developing regulatory standards for clearing equipment and materials with residual radioactivity from nuclear facilities. In addition to equipment reuse, the analysis identifies material flow models, based on U.S. industry practices, for recycle of steel, copper, aluminum, and concrete.
Using information from the material flow models, likely potential exposure scenarios were realistically modeled for the recycle of these materials. Scenarios for copper, aluminum, and l concrete were based on the steel scenarios, but were modified to reflect differences in each l industry, and additional exposure scenarios unique to each material were included. The modeling includes all significant exposure pathways, and scenarios include handling and processing, storage, transportation, product use, and disposal. The results of the analyses are expressed in both mass end surficial units. Using Monte Carlo techniques, distributions of radionuclide concentrations were estimated in the material flow model, and concentrations at selected points in the process were used as inputs to the dose assessment model for each scenario. Probability di.stributions for dose factors (along with the mean, median, and 5* and 95th percentilele values) were estimated for each radionuclide and each scenario. Fe* each material (e.g., steel), a critical broup was identified for each radionuclide, which represents the scenario with the highest mean dose factor. Appendices containing details of the analysis and tabulations of results are included.
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iii Draft NUREG-1640, Vol. I
e CONTENTS-
[N . $
VOLUME I (Main Report) i!J V Eau
! A bstrac t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Executive S ummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . xvii Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix !
L Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx i i l Units Conversion Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii I 1
i l l
1 INTRODUCTION -
1-1 !
1.1 Purpose and Scope
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Technical Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 -2 1.3 Results Presented ................................................ 1-6 2
SUMMARY
AND COMPARISON OF RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 l 2.1 Dose Factors for Members of Critical Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 i 2.2 Comparison of Results with Other Clearance Criteria . . . . . . . . . . . . . . . . . . . . . 2-8 l 2.2.1 Comparison with Regulatory Guide 1.86 . . . . . . . . . . . . . . . . . . . . . . . 2-8 l 2.2.2 Comparison with the Environmental Protection Agency . . . . . . . . . . 2-11 2.2.3 Comparison with the European Commission . . . . . . . . . . . . . . . . . . . 2-11
'2.2.4 Comparison with the International Atomic Energy Agency . . . . . . . . 2-14
- i L( 3. EVALUATION OF DIRECT REUSE OF EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 ;
l 3.1 Direct Reuse Scenario Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 L 3.2 Exposure Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 -3 3.2.1 External Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.2.2 Inhalation Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.2.3 Secondary Ingestion Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.2.4 Total Dose from Equipment Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.3 Discussion of Models and Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 i 3.3.1 External Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
- l. 3.3.2 Inhalation Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 1
3.3.3 Secondary Ingestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11 3.4 Reuse Scenario Evaluation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 i
4 EVALUATION OF RECYCLE AND DISPOSAL OF STEEL SCRAP . . . . . . . . . . . . . . 4-1 4.1 Introduction to Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 j 4.1.1 Approach to Scenario Development . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.1.2 Scenarios for Recycle and Disposal of Cleared Steel Scrap Metal . . . . 4-4
- 4.2 Flow of Recycled and Disposed Steel Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 l
> 4.2.1 Conceptual Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
' 4.2.2 Sources of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4.2.3 Transportation and Processing of Scrap . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 h
A 4.2.3.1 Integrated Steel Mills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 v Draft NUREG.1540, Vol. I
Cont;nts .
Ene 4.2.3.2 Non-Integrated Steel Mills . . . . ........ .... . . 4-9 4.2.3.3 Output of Refinery Processes . . . . .. .... . . . . . . . 4- 12 4.2.4 Disposition of EAF Baghouse Dust . . . ......... ... .. . 4-14 i 4.2.5 Product Use . . . . . . . . . . . . . . . . . . . ....... ................ 4-15 l 4.2.6 Disposal . . . . . . . . . ..... ......... ... ..... ...... .. 4-15 4.3 Mass and Elemental Partitioning Factors for Refinery Operations . . . . . . . . . . 4-15 4.3.1 Mass Partitioning Factors ....... ........... . . . . . . . . . . .. . 4 - 1 6 4.3.1.1 Metal Product . . . . . . . . .... . . ................ 4-16 4.3.1.2 Baghouse Dust . . . . . . . . . . . . . . . . . . . . . . . . . ...... . 4-16
- 4. 3.1.3 ' S lag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......... 4-17 4.3.1.4 Basic Oxygen Furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18 4.3.2 Elemental Partitioning Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19 4.3.2.1 Basic Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19 4.3.2.2 General Methodology for Determining Elemental Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 0 4.3.2.3 Comparison of Partitioning Factors with Published Studies . 4-22 4.4 Mathematical Model for Flow of Recycled Steel Scrap . . . . . . . . . . . . . . . . . . 4-23 4.4.1 S crap Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23 4.4.2 Re finery Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24 4.4.3 EAF Dust Hazardous Landfill .......... ................... 4-27 4.5 Radioactivity Concentrations in Steel Refining Co-products . . . . . . . . . . . . . . 4-27 4.6 Dose Assessment for Steel Recycle and Disposal . . . . . . . . . . . . . . . . . . . . . 4-27 .
i 4.6.1 General Description of Recycle Scenarios . . . . . . . . . . . . . . . . . . . 4-27 4.6.2 Work-Related Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 5 4.6.2.1 Handling Scenarios . . . . . . . ... ...................4-35 4.6.2.2 Processing Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-40 4.6.2.3 Storage Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-41 4.6.2.4 Product Use Scenarios-Workers . . . . . . . . . . . . . . . . . . . 4-41 4.6.2.5 Transportation Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-42 4.6.2.6 Disposal Activities Scenarios ....... .............. 4-44 4.6.3 Description of Non-worker Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . 4-46 4.6.3.1 Refinery Atmospheric Releases . . . . . . . . . . . . . . . . . . . . . 4-46 4.6.3.2 Storage Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-49 4.6.3.3 Product Use Scenarios-Non-workers . . . . . . . . ...... . 4-52 4.6.3.4 Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 6 4.6.3.5 Resident on Closed Landfill . . . . . . . . . . . . . . . . . . . . . . 4-56 4.6.4 Environmental Media Concentrations Resulting from Environmental Transport . . . . . ......... ........... . .. ........ .... 4-66 4.6.4.1 Atmospheric Releases (Source Term, Dispersion, Media Concentration) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-66 4.6.4.2 Drinking Water Concentrations . . . . . . . . . . . . . . . . . . . . . . 4-71 4.6.~4.3 Food and Soil Concentrations . . . . . . . . . . . . . . . . . . . . . . 4-77 4.6.5 Exposure Pathway Doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-80 4.6.5.1 External Exposure Pathway .................... ... 4-80 4.6.5.2 inhalation Exposure Pathway . . . . . . . . . . . . . . . . . . . . . . . 4-83 Draft NUREG-1640, Vol. I vi
Contents Een 4.6.5.3 Inadvertent Secondary Ingestion Exposure Pathway . . . . . . 4-85 !
O 4.6.5.4 Water Ingestion . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 4-86 l
'd 4.6.5.5 Ingestion of Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-86
)
4.7 Derived Surficial Dose Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-89 I 4.8 Parameter Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-90 I i
4.8.1 Radionuclide Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-90 4.8.2 Material Flow Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-92 4.8.3 Scenario Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-92 4.8.4 Dose Evaluation . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-94 4.8.4.1 Input Radionuclide Concentrations from the Material Flow . 4-94 4.8.4.2 Exposure Duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-94 4.8.4.3 Material Densities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-96 4.8.4.4 Mixing of Cleared Material . . . . . . . . . . . . . . . . . . . . . . . . . 4-97 )
4.8.4.5 External Exposure Parameters . . . . . . . . . . . . . . . . . . . . . . . 4-99 j 4.8.4.6 Inhalation Exposure Parameters . . . . . . . . . . . . . . . . . . . . . 4-100 l 4.8.4.7 Inadvertent Secondary Ingestion Exposure Parameters . . . 4-104 l 4.8.4.8 Drinking Water Ingestion Exposure Parameters . . . . . . . . . 4-104 I 4.8.4.9 Ingestion Exposure Parameters . . . . . . . . . . . . . . . . . . . . . . 4-106 ;
4.8.4.10 Atmospheric Release Parameters . . . . . . . . . . . . . . . . . . . 4-107 j 4.8.4.11 Landfill Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-108 J 4.8.5 Steel Surface-to-Mass Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-111
. 4.9 Dose Factors for Recycle of Steel Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-111 5 EVALUATION OF RECYCLE AND DISPOSAL OF COPPER SCRAP . . . . . . . . . . . . 5-1 l
5.1 Introduction to Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 1 l 5.2 Flow of Recycled and Disposed Copper Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2.1 Sources of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2.2 Transportation and Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
' 5.2.3 Copper Mills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4 l
5.2.3.1 Reverberatory Furnace . . . . . . . . . . . . . . . . . . . . . . . . . .... 5-4 5.2.3.2 Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 5.2.3.3 Electrorefiner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 l 5.2.3.4 Output of Refinery Processes . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 ,
5.2.4 Product Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 i 5.2.5 D i spo sal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5.3 Mass and Elemental Partitioning Factors for Refinery Operations . . . . . . . . . . . 5-7 5.3.1 Mass Partitioning Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 5.3.2 Elemental Partitioning Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 5.4 Mathematical Model for Flow of Recycled Copper Scrap . . . . . . . . . . . . . . . . . 5-8 5.4.1 Mixing of Cleared and Other Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 5.4.2 Refinery Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 1 1 '
5.5 Radioactivity Concentrations in Copper Refining Co-products . . . . . . . . . . . . . 5-13 5.6 Dose Assessment for Unique Copper Recycle and Disposal Scenarios . . . . . . 5-20 5.6.1 Exposure Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 p 5.6.2 Mathematical Representation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 t
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N vii Draft NUREG-1640, Vol.1
Cont:nts Paee 5.7 Parameter Discussion for all Modeled Scenarios . . .. . . .... .. . 5-21 5.7.1 Scenario Tiraing . . . . . ...... .... ......... ......... .. 5-22 5.7.2 Dose Evaluation . . ................ .. ............ .. . 5-23 5.7.2.1 Input Concentrations from the Material Flow . . . .... . 5-23 5.7.2.2 External Exposure Parameters . . . . . ...... .. .. 5-23 5.7.2.3 Ingestion Exposure Parameters . . . . . . ........ ... 5-23 5.7.2.4 Atmospheric Release Parameters . . . . . . . . . . . . . . . . . . 5-24 5.8 Dose Factors for Recycle and Disposal of Cepper Scrap . . . . . . . . . . . . . . . . . 5-25 6 EVALUATION OF RECYCLE AND DISPOSAL OF ALUMINUM SCRAP ..... .. 6-1 6.1 Introduction to Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 6.2 Flow of Recycled and Disposed Aluminum Scrap . . . . . . . . . . . . . . . . . . . 6-1 6.2.1 Sources of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 6.2.2 Transportation and Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 6.2.3 Aluminum Mills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4 6.2.4 Product Use . . . . . . . . . . . . . . . . . . . . ............... ........ 6-5 6.2. 5 D isposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5 6.3 Mass and Elemental Partitioning Factors for Refinery Operations . . . . . . . . . . . 6-6 6.3.1 Mass Partitioning Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 6.3.2 Elemental Partitioning Factors . . . . . . . . . . . . . . . . .... ... ..... 6-6 6.4 Mathematical Model for Flow of Recycled Aluminum Scrap . . . . . . . . . .... 6-7 6.4.1 Mixing of Cleared Scrap and Other Scrap . . . . . . . . . . . . . . . . . . . . . . . 6-7 6.4.2 Refinery Process ......................................... 6-9 6.5 Radioactivity Concentrations in Aluminum Refining Co-Products . . . . . . . . . . 6-11 6.6 Dose Assessment for Unique Aluminum Recycle and Disposal Scenarios ... 6-12 6.6.1 Exposure Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 12 6.6.2 Mathematical Representation . . . . . . . . . ..................... 6-12 i 6.7 Parameter Discussion for All Modeled Scenarios ...................... 6-16 6.7.1 Scenario Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 16 6.7.2 Dose Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 16 6.7.2.1 Input Concentrations from the Material Flow . . . . . . . . . . . 6-16 6.7.2.2 External Exposure Parameters . . . . . . . . . . . . . . . . . . . . . . . 6-17 6.7.2.3 Ingestion Exposure Parameters . . . . . . . . . . . . . . . . . . . . . . . 6-17 6.7.2.4 Atmospheric Release Parameters ....... . ......... 6-18 6.7.3 Aluminum Surface-to-Mass Ratio . . . . . . . . . . . . . . . . . . . . . . . . . 6-18 6.8 Dose Factors for Recycle and Disposal of Aluminum Scrap . . . . . . . . ..... 6-18 7 EVALUATION OF RECYCLE AND DISPOSAL OF CONCRETE . . . . . . . . . . . . . . . 7-1 7.1 Introduction to Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7.2 Flow of Recycled and Disposed Concrete . . . . . . . . . . . . . ... .......... . 7-2 7.2.1 Source of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 7-3 l 7.2.2 Transportation and Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 7.2.3 Manufacturing . . . . . . . . .. .. ....... .... ........... 7-4 7.2.4 Product Use . . . . . . . . . . . . . .. ..... ... .. ...... .. .... 7-4 7.2.5 Disposal . . . . . . .......................... ........... . 7-4 Draft NUREG-1640. Vol.1 'viii l
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l 1
I l
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Contents W l 7.3 Mathematical Model for the Flow of Recycled Concrete Debris . . . . . . . . . . . 7-4 O)
\f 7.4. Radioactivity Concentrations in Concrete Recycle Products . . . . . . . . . . . . . . . . 7-5 7.5 Dose Assessment for Concrete Recycle and Disposal . . . . . . . . . . . . . . . . . . . . . 7-6 7.6 Parameter Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 7.6.1 Scenario Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 7.6.2 Dose Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7 7.6.2.1 Input Concentrations from the Material Flow . . . . . . . . . . . . 7-7 7.6.2.2 External Exposure Parameters . . . . . . . . . . . . . . . . . . . . . . . . 7-7 7.6.3 Concrete Surface-to-Mass Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7 7.7 Dose Factors for Concrete Recycle and Disposal . . . . . . . . . . . . . . . . . . . . . . . . . 7-8 8 QUALITY CONTROL PROGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8.1 Technical Approach to Model Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2 8.2 Quality Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 8.3 Document Review, Control and Configuration Management ............... 8-5 8.4 QA Review of Technical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
8.5 Recordkeeping
Project Engineering Cabinet . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5 8.6 Instructions for Naming Files and Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7 l 9 RE FE RENC ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9- 1 G L OS S ARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . g lo ssary- 1 Tables
,O Table 2.1 Mass-based critical-group dose factors for recycle and disposal of cleared materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Table 2.2 Surficial critical-group dose factors for recycle and disposal of cleared materials . 2-6 Table 2.3 Comparison of derived NRC clearance levels with Regulatory Guide 1.86 acceptable contamination levels (across all materials) . . . . . . . . . . . . . . . . . . . . . . 2-9 Table 2.4 Comparison of NRC mass-based steel recycle critical-group dose factors with E PA va! ues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12 Table 2.5 Comparison of derived NRC clearance levels with European Commission values (all metals) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 15 Table 2.6 Comparison of derived NRC clearance levels with IAEA values (all materials) . 2-18 Table 3.1 Representative reported indoor resuspension data and recommended values . . . . 3-7 Table 3.2 Dose factors for reuse of a large piece of equipment . . . . . . . . . . . . . . . . . .... 3-14 Table 4.1 Scenarios discussed in previous studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 Table 4.2 Key assumptions for the steel material flow model . . . . . . . . . . . . . . . . . . . . . . . 4-11 Table 4.3 Values used for calculation of EAF mass partitioning factors (metric tons per c harge) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 4 - 1 7 Table 4.4 Values used for calculation of BOF mass partition factors (metric tons j per charge) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 19 L
Table 4.5 Elemental partitioning factors (EPFs) for mel . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22 Table 4.6 Results of material flow medel-steel electric are furnace . . . . . . . . . . . . . . . . . 4-28 Table 4.7 Results of material flow model- steel basic oxygen furnace . . . . . . . . . . . . . . . 4-31
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ix Draft NUREG.1640, Vol.1 I-I
Contents Page Table 4.8 Scenario and exposure pathway matrix . . . . . . . . . .. ..... .. .. . . 4-33 Table 4.9 Radionuclides ofinterest for recycle, disposal, and reuse of equipment and m a te ri al . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-91 Table 4.10 Steel recycle critical-group dose factors-mass . . . . . . . . . . . . . . . . .. . . 4-115 Table 4.11 Steel recycle critical-group dose factors-surficial . . . . . . . . .... .. 4-118 Table 5.1 Elemental partitioning factor ranges (%) for copper refining . . . . . . . . . . . .. 5-9 Table 5.2 Results of material flow model-copper reverberatory furnace . . . . . . . . . . . 5-14 Table 5.3 Results of material flow model-copper converter furnace . . . . . . . . . . . . 5- 16 Table 5.4 Results of material flow model-copper electrorefinery . . . . . . . . . . . . . . . . . 5-18 Table 5.5 Copper recycle critical-group dose factors-mass . . . . . . . . ........... 5-27 Table 5.6 Copper recycle critical-group dose factors-surficial . . . . . . . . . . . . . . . . . 5-30 Table 6.1 Key modeling assumptions for aluminum secondary smelter . . . . . .. .. ... 6-4 Table 6.2 Elemental partitioning factor ranges (%) for aluminum refining . . . . . . . . . . . . . 6-8 Table 6.3 Results of material flow model-aluminum refinery . . . . . . . . . . . . . . . . . . . 6-13 Table 6.4 Aluminum recycle critical-group dose factors-mass . . . . . . ........... 6-21 Table 6.5 Aluminum recycle critical-group dose factors-surficial . . . . . . . . . . . . . . . . . 6-24 Table 7.1 Results of concrete material flow model . . . . . . . . . . . . . . . . . . . . . . . . .. 7-5 Table 7.2 Concrete recycle critical-group dose factors-mass . . . . . . . . . . . . . . 7- 10 Table 7.3 Concrete recycle critical-group dose factors-surficial . . . . . . ...... . 7-13 Figures Figure 1.1 Relationship of the critical group to other exposed groups . . . . . . . . ... ..... 1-4 l Figure 4.1 Flow of steel scrap . . . . . . . . . . . . . . . . ........ ...... ....... .... . 4-6 Figure 4.2 Generic refining process . . . . . . . . . . . . . . . . . . . . . . . . . ................. 4-8 l Figure 4.3 Modeling approach for atmospheric releases from a refinery . . . . . . . . . . . . . . . 4-47
. Figure 4.4 Three-box compartment model for the storage of slag scenario . . . . . . . . . . . 4-50 Figure 4.5 Modeling approach for resident on a closed landfill . . . . . . . . . . . . . . . . . . . . . . 4-58 Figure 4.6 Three-box compartment model for surface-to-groundwater transport for resident on closed landfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4-63 l
Figure 4.7 Scenarios describing critical groups for steel recycle . . . . . ............ . 4-113 l Figure 5.1 Material flow for copper scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Figure 5.2 Scenarios describing critical groups for copper recycle . . . . . . . . . . . . . . . . . 5 -2 6 Figure 6.1 Material flow for aluminum scrap . . . . . . . . . . . . . . . . . . . .. . ......... 6-2 Figure 6.2 Scenarios describing critical groups for aluminum recycle . . . . . . . . . . . . . . . . 6-2 0 Figure 7.1 Conceptual model for the overall flow of recycled and disposed concrete . . . . . 7-2 Figure 7.2 Scenarios describing critical groups for concrete recycle . . . . . . . . . . . . ... 7-9 Draft NUREG-1640. Vol. I x O
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Contents Eeze APPENDIX B Parameter Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . B-1
) APPENDIX C External Exposure Dose Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 d APPENDIX D Mixing of Cleared Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... D-1 l APPENDIX E Radioactive Decay and Progeny Ingrowth . . . . . . . . . . . . . . . . . . . . . . . . . . E-1 APPENDIX F Dose Factors for Steel Recycle Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . F-1 l
APPENDIX G Dose Factors for Copper Recycle Scenarios . . . . . . . . . . . . . . . . . . . . G-1 APPENDIX H Dose Factors for Aluminum Recycle Scenarios . . . . . . . . . . . . . . . . . . . . H-1 l APPENDIX I Dose Factors for Concrete Recycle Scenarios . . . . . . . . . . . . . . . . . . . . . . . I-l i APPENDIX J ' Illustrative Specific Applications of Generic Methods ................. J-l i
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EXECUTIVE
SUMMARY
A h This report provides the technical basis for the Nuclear Regulatory Commission (NRC) to base regulatory standards for clearance of equipment and materials with residual radioactivity from regulatory control. The goal of the analyses is to identify realistic critical groups resulting from clearance of equipment and materials from NRC licensed facilities and to calculate dose factors for the average member of each critical group. The methods described in this report address both surficially contaminated equipment and volumetrically contaminated scrap materials.
In order to ensure that the reuse and recycle assessments are defensible, accurate, and verifiable, a Quality Control Plan (QCP) was prepared for and followed during this evaluation. The QCP specifies procedures and conventions for develogang the reuse and recycle models, defining equadons and definitions, and implementing spreadsheets. Also included in the QCP are requirements for preparing and reviewing calculations and recording and documenting technical information. The QCP provides a documented system for ensuring accurate results, as well as a method for tracing the bases of assumptions. The QCP incorporates quality assurarse guidelines provided by the NRC and other recognized authoritative references.
4 Dose factors for both surficial and volumetric residual radioactivity were calculated in this analysis. The dose factors, as well as derived clearance levels, are compared to values from other documented sources. The dose factors used for deriving clearance levels for each radionuclide are the critical-group dose factors (the mean value of the distribution calculated from the model for each critical group). These dose factors represent the total effective dose equivalent (TEDE) k for an average individual in the critical group for each radionuclide. The dose factors are normalized and are expressed in units of annual dose per unit of residual radioactivity. The recycle clearance levels for each radionuclide are based on the highest critical-group dose factors across the materials that are appropriate for comparison (steel, copper, aluminum, and concrete).
The recycle scenario critical group is not the same for each radionuclide, due to the complex nature of the recycle analyses (e.g., differential behavior during melting, wide range of scenario categories, and different types of scrap material). The majority of clearance levels are based on critical groups that involve either commercial truck drivers or workers at processing facilities.
With only two exceptions, the recycle (volumetric) critical-group dose factors are more restrictive than the equipment reuse (surficial) clearance levels, primarily because of the much smaller amount of radioactivity involved in the equipment reuse scenario analyses.
The wide range of radionuclide-specific clearance levels derived from the dose factors in this report compare inconsistently with those contained in Regulatory Guide 1.86. Using a clearance criterion of 10 Sv/y, approximately half of the derived radionuclide-specific clearance levels in this report are within a factor of 10 of the acceptable surface contamination levels in Regulatory Guide 1.86. Most of the remaining are greater than a factor of 10 higher than the Regulatory Guide values, indicating that the derived clearance levels in this report are less restrictive than Regulatory Guide 1.86.
V xiii Draft NUREG 1640, Vol.1
Executive Summary Critical group dose factors from this analysis are similar to the draft dose factors published by the EPA. For 36 of the 40 radionuclides in common, the dose factors are within a factor of 10, indicating that the two sets of dose factors are in general agreement. Derived clearance levels do not compare as well to clearance levels from international sources. Using a common clearance criterion of 10 Sv/y, between 50% and 75% of the derived clearance levels for radionuclides in common are within a factor of 10 of the clearance levels published by the European Commission and International Atomic Energy Agency. For those derived clearance levels that are greater than a factor of 10 different in these two sources, the derived clearance levels in this report are more restrictive for all but one radionuclide in each comparison.
Reuse of equipment and recycle of materials were both evaluated and are described in this report.
Equipment reuse scenarios differ from recycle scenarios in three ways: (1) only suru .at contamination is modeled, (2) the cleared equipment is not processed, and (3) different material types are not considered. A generic equipment reuse scenario was selected for detailed evaluation based on a qualitative screening evaluation of potential equipment reuse exposure scenarios. Modeling the reuse of a large piece of contaminated equipment resulted in dose factors for each radionuclide that bound all other equipment reuse scenarios considered. Thus, it was not necessary to model other equipment reuse scenarios. Exposure pathways included in the dose evaluation are external, inhalation, and secondary ingestion. The mathematical equations ,
and parameter values used to evaluate the scenario ve presented, as well as a discussion of key parameter values. The exposure pathways analyzed produce reasonable estimates of the potential TEDE that a member of the critical group could receive.
Recycled material was evaluated using material flow models and dose assessment models. Both models are based on probabilisti c methods. Input parameters are modeled as distributions instead of point values (because of uncertainty in the values) resulting in distributions for the output values (i.e., radionuclide concentrations and dose factors).
The material flow model is material-specific and describes the flow of cleared material beginning with the refining process (for metals) or the processing steps (for concrete) through the generation of consumer products. In the material flow model, the original concentration of radionuclides in the cleared material is redistributed to all the products of the process, such as baghouse dust and off-gas, as well as consumer products. The radionuclide concentrations calculated from the material flow model are used as input to the models that estimates potential dose factors for the various scenarios.
The material flow models were also used'to identify all the reasonably possible exposure scenarios within the context of the current recycle industries. Approximately 50 potential
! scenarios were screened and consolidated to form set. of 31 exposure scenarios (generic and specific) that were analyzed for the recycle of cleared steel. The scenarios comprise five general categories of potential exposure: handling and processing, storage, transportation, product use, and disposal. Within these categories, five source materials were examined: scrap metal, refinery slag, baghouse dust, refined metal, and atmospheric emissions from refineries.
O Draft NUREG-1640, Vol. I xiv
Executive Summary
' Radionuclide-specific dose factors were calculated for all scenarios using the dose assessment
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t Exposure scenarios developed for clearance of steel served as the basis for the evaluation of three other materials (copper, aluminum, and concrete). Scenarios unique to each of the other materials were also analyzed. These unique scenarios involve the use of refined copper in
~ household plumbing, use of refined aluminum in cookware, and a resident on the site of a closed landfill containing recycled concrete. Twenty-three scenarios were analyzed for copper recycle-and 17 for aluminum recycle. Because of the lack of refining coproducts, there are fewer potential scenarios for concrete recycle (7 scenarios). Using the same methodology used for the steel evaluation, radionuclide-specific dose factors were calculated for all scenarios for these three additional materials.
The analyses were conducted using Monte Carlo techniques to develop probability distributions of the radionuclide concentrations given by the material flow model and of the scenario dose factors.' Specific values tabulated from the output distributions consist of the mean dose factors
.for each exposed group, the median of each distribution, and upper (95* percentile) and lower (5* percentile) values from the distributions. The upper and lower values represent the range of a 90% confidence interval for each radionuclide-specific dose factor. The ratio between the upper and lower bounds of the confidence interval indicates the width of the distribution and is a
- measure of the uncertainty associated with each dose factor.
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Calculated dose factors for an average member of the critical group in the reuse scenario are based on a unit level of residual surficial contamination and are expressed in normalized units of pSv/y per Bq/cm 2(mrem /y per pCi/cm 2). Dose factors range from a high of 170 pSv/y per Bq/cm2(0.6 mrem /y per pCi/cm2 ) for Th-229 to a low of 1E-05 Sv/y per Bq/cm2. Most of the eighty-five radionuclide-specific dose factors (approximately two-thirds) are less than 10 pSv/y per Bq/cm2(0.04 mrem /y per pCi/cm 2). The size of the confidence intervals (i.e., the range from the 5* percentile value to the 95* percentile value) for dose factors in the equipment reuse scenario fall into two groups. For about half the nuclides, the confidence interval ratio is close to 5 (ratio of 95* percentile to 5* percentile values). The remaining nuclides have confidence interval ratios that range from about 10 to about 40. The unique radiological characteristics of each group are responsible for the wide range of ratios. Calculated dose factors that are dominated by inhalation and ingestion exposure pathways have wider con 6dence intervals (greater uncertainty) than dose factors dominated by the external exposure pathway.
Dose factors for the steel recycle analysis range from a high of 2,000 Sv/y per Bq/g (7 mrem /y per pCi/g) for Np-237 to a low of 4E-04 Sv/y per Bq/g. The derived surficial mean critical group dose factors for steel recycle range from 1,400 Sv/y per Bq/cm2 (Np-237) to a low of 3E-04 pSv/y per Bq/cm 2. The Np-237 dose factor results from the drinking water exposure
_ pathway in a refinery slag storage scenario. Only 6 of the 85 radionuclide-specific dose factors are greater than 270 pSv/y per Bq/g (1 mrem /y per pCi/g). Occupational doses associated with transportation and refinery facilities most commonly produce the critical groups for steel recycle.
O O xy Draft NUREG 1640, Vol.1 a:
r Executive Summary Results for recycle of copper and aluminum generally yield similar-although lower-dose factors. Copper recycle dose factors range from a high of 300 pSv/y per Bq/g (1 mrem /y per pCi/g) for Th-229 to a low of 4E-04 Sv/y per Bq/g. The derived surficial mean critical group dose factors for copper recycle are numerically the same, range from 300 Sv/y per Bq/cm 2 (Th-229) to a low of 4E-04 Sv/y per Bq/cm .2 Aluminum recycle dose factors range from a high of 6 Sv/y per Bq/g (.02 mrem /y per pCi/g) for Ag-110m to a low of 2E-06 pSv/y per Bq/g. The derived surficial mean critical group dose factors for aluminum recycle range from 23 pSv/y per Bq/cm2 (Ag-110m) to a low of 7E-06 Sv/y per Bq/cm .2 As in the steel evaluation, most of the 85 radionuclide-specific dose factors for both copper and aluminum are less than 270 Sv/y per Bq/g (1 mrem /y per pCi/g). Also similar to the steel evaluation, occupational doses associated with transportation and refinery facilities most commonly result in critical groups for copper and aluminum. One copper product-use scenario results in a critical group for copper recycle (use of a generic small copper object), and use of aluminum products accounts for several critical groups in the aluminum recycle analysis.
The mass-based concrete recycle dose factors are generally higher than those calculated for metals recycle, ranging from a high of 7E+04 Sv/y per Bq/g (300 mrem /y per pCi/g) for Np-237 to a low of 3E-03 Sv/y per Bq/g. The derived surficial mean critical group dose factors 2
for concrete recycle range from 1,400 Sv/y per Bq/cm (Np-237) to a low of SE-05 Sv/y per 2
Bq/cm . Approximately 90% of the 85 radionuclide-specific dose factors are less than 270 Sv/y per Bq/g (1 mrem /y per pCi/g). Unlike the metals, a scenario involving a resident on a closed landfill was analyzed and included in the critical group determination. This r,cenario accounts ,
for one hird of the critical groups for concrete recycle.
Examining the distributions associated with the calculated dose factors for each recycle exposure scenario provides some additional information. Simple scenarios, with only a few exposure pathways and relatively well-known parameters, have distributions that are fairly narrow. For example, the dose factors associated with the commercial truck driver scenarios have confidence interval ratios that range from 2 to about 15 (ratio of 95* percentile to 5* preentile valuesh Confidence intervals are much wider for complex scenarios with many parameters and uncertain pathways of exposure, such as food-chain intake, groundwater transport, and atmospheric dispersion. The scenarios ducribing residents on closed landfills containing concrete debris and individuals near large slag storage piles exhibit the greatest range. The confidence interial ratios for these scenarios range from about 150 to about 650.
Appendices included as Volume 2 of this report provide details of the extensive calculations used in this evaluation of reuse and recycle. Radionuclide-specific data such as dose conversion factors and environmental transport factors are included, as well as parameter values for all materials and scenarios. j Draft NUREG-1640, Vol. I xvi O
f FOREWORD
' The NRC has initiated a rulemaking on clearance. Clearance is the removal of equipment or materials from regulatory control with respect to their radiological properties. Internationally, the custom is to set radioactive levels so low that the risks are widely accepted as trivial. An early step in the clearance process is estimating potential doses to individuals for the various regulatory attematives that must be examined in the generic environmental impact statement (GEIS).
This report, now issued as a draft for public review and comment, presents the analyses and results of 79 scenarios that were reasonable candidates for identifying the critical group for the respective materials. The analyses were performed on a nuclide-by-nuclide basis for the 85 nuclides most likely to be associated with scrap and equipment from nuclear facilities. The work was carried out under a formal quality assurance and quality control program over a 6-year period. The analyses were performed with substantial cooperation and consultation from the EPA and the DOE. Peer review performed by Drs. F. Owen Hoffman and Kathleen M. Thiessen of SENES, Oak Ridge, Tennessee, is reflected in this report.
The purpose of this report is to calculate realistic estimates ofthe dosefactorsfor the average member ofthe criticalgroup associated with the clearance ofequipment and ofscrap iron and steel, copper, aluminum, and concrete on a radionuclide-by-radionuclide basis. 1 A
U e " Realistic" estimates are estimates using scenarios and models whose parameters are based on current general practices of the U.S. nuclear power industry. " Realistic" also refers to the probability of a scenario. Many conceivable scenarios were not considered because they were too improbable.
e "r timates" s implies uncenainty in the dese factors. Accordingly, the uncertainties are quantitatively estimated, e Dose factors are expressed in terms of annual radiation dose (pSv/y) for each unit of radioactivity (Bq) on a unit surface area (cm 2) of equipment or scrap or in a unit of mass (g) of scrap.
e The "averaFe member of the critical group" is, for dose assessment purposes, the hypothetical member whose dose factor is equal to the mean of the distribution of calculated dose factors for the critical group.
e The " critical group" is the group ofindividuals reasonably, or realistically (as defined above), expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances (10 CFR 20.1003).
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1 Foreword Comments will be most useful if they focus on achieving the purpose of this report. Comments are especially sought on the technical aspects of this report and will be most welcome if received within 90 days ofits publication.
In revising the report, the NRC will not consider information submitted in comments unless it is independently verifiable. Data must be reproducible and the sources of data cited. To qualify for consideration, comments must also estimate the frequency of occurrence of any recommended changes (which should be greater than 1 in 100,000), and must give sufficient explanation to provide a rationale in the final report. Furthermore, qualified comments must explicitly accept or verify the results in the task report, or else recommend changes in the models or in the mathematical formulations of the models or changes in the ranges and distributions of model ,
parameters. The changes must be supported by a clear rationale and citable sources of data.
Comments both from the U.S. Nuclear Regulatory Commission (NRC) staff and from persons outside the NRC should be submitted in writing directly to Chief, Rules and Directives Branch, U.S. Nuclear Regulation, T6-D59, Washington, DC 20555, or hand-delivered to 11545 Rockville Pike, Rockville, Maryland, between 7:15 a.m. and 4:30 p.m. on Federal workdays. Comments may also be submitted while viewing this report on the Intemet at the following URL:
htto://www.nre.cov/NRC/NUREGS/SR 1640/DR AFT /index.html .
Iohn W. Craig, Director Division of Regulatory Applications Office of Nuclear Regulatory Research I
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Draft NUREG-1640, Vol. I xviii
[] ACKNOWLEDGMENTS ,
1 This report presents information that was developed as a result of the contributions of many individuals over several years. l l l Project Officer: Robert A. Meck l
l Principal authors of the report: l Mary E. Anderson (Science Applications Michael A. McKenzie-Caner (SAIC) i
- l. Intemational Corporation, [SAIC]) Mark D. Otis (SAIC)
Reginald L. Gotchy (SAIC) James A. Roberts (SAIC)
Other key contributors: i Morris A. Hall (SAIC) Kirt R. Marlow (SAIC)
William E. House (SAIC) Robert A. Meck
- Gary Leatherman (Lockheed Martin Idaho Howard K. Pippen (SAIC) l Technologies Company) George E. Santee, Jr. (SAIC)
Document production:
Carolyn Einerson (TechWrite) Martha J. Reisenauer(SAIC)
Linda D. Hellewell(SAIC)
Rayleona (Ray) Sanders Lisa W. Marko (SAIC)
Technical reviewers:
l Frank P. Cardile Robert A. Meck Giorgio N. Gnugnoli Robert A. Nelson l F. Owen Hoffman (SENES, Oak Ridge) Kathleen M. Thiessen (SENES, Oak l Anthony M. Huffert Ridge)
Cynthia G. Jones l
Collaborators:
Robert Anigstein (Sandy Cohen & Associates, John MacKinney (EPA)
[SC&A]) John Mauro (SC&A)
S. Y. Chen (Argonne National Laboratory [ANL]) Bassel Nabelssi(ANL)
Kenneth Duvall (Department of Energy [ DOE]) Bill Thurber (SC&A)
Reid Harvey (Environmental Protection Agency Andrew Wallo,III(DOE)
, [ EPA]) Charley Yu (ANL) l John Karhnak (EPA)
In addition to those listed above, the authors acknowledge the assistance of many individuals from the secondary metals industries, recycling facilities, and trade groups who provided essential details needed for the development and refinement of the analyses.
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ABBREVIATIONS
&)
. AEC Atomic Energy Commission l
AIHC American Industrial Health Council
. AISE Association ofIron and Steel Engineers AISI American Iron and Steel Institute ALARA as low as is reasonably achievable BOF basic oxygen f mace BWR boiling water reactor CRC. Chemical Rubber Company D&D decontamination and decommissioning DCF dose conversion factor DF dilution factor DOD Department of Defense
' DOE Department of Energy DWL ~ derived working limits EAF electric arc fumace EC. European Commission ,
EDE effective dose equivalent j EDF engineering design f le !
' EPA Environmental Protection Agency i EPF elemental partitioning factor EPRI Electric Power Research Institute EPS east pile slag Q FGR GF Federal Guidance Report geometry factor IAEA International Atomic Energy Agency ICRP . International Commission on Radiological Protection LANL Los Alamos National Laboratory LLW low-level radioactive waste MCNP Monte Carlo N-Particle MPC maximum permissible concentration MPF mass partitioning factor NCRP National Council on Radiation Protection and Measurements NIOSH National lastitute of Safety and Health NRC Nuclear Regulatory Commission OSHA Occupational Safety and Health Administration PWR pressurized water reactor QA Quality Assurance
'QCP Quality Control Plan RCRA Resource Conservation and Recovery Act SAIC Science Applications Intemational Corporation SC&A Sandy Cohen and Associates TDS total dissolved solids TEDE. total efrective dose equivalent TSD . Technical Support Document USBM United States Bureau of Mines b
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UNITS CONVERSION TABLE This analysis was conducted using conventional units (e.g., radioactivity units of curies {Ci],
dose in units of rem). In the interest of promoting the use ofinternationally accepted units, the results of the analysis have been converted to S.I. units (e.g. , radioactivity units of becquerel [Bq]
dose in units of sievert [S]). Units in the text discussion are primary in units of S.I. tmits, followed by conventional units in parentheses. Because the analysis was conducted using conventional units, parameter units listed with equations are maintained in conventional units.
The following table gives factors for converting from conventional units to S.I. units.
To convert from To Multiply by degrees Fahrenheit ( F) degrees Celsius ('C) subtract 32 'F, then multiply by 0.556 short tea (ton) kilogram (kg) 907.2 short ton (ton) metric ten (t) 0.9072 pounds per ton (Ibs/ ton) kilogram per metric ton (kg/t) 0.5 cubic yard (yd') 2 cubic meter (m ) 0.7646 2
cubic foot (ft') cubic meter (m ) 0.02832 curie (Ci) becquerel (Bq) 3.7E+ 10 picoeurie (pCi) becquerel (Bq) 0.037 picoeurie per square centimeter bequerel per square centimeter 0.037 (pCi/cm )2 (Bq/cm )2 picoeurie per gram (pCi/g) bequerel per gram (Bq/g) 0.037 picocurie per gram of product per bequerei per gram of product per 1.0 picoeurie per gram of scrap bequerel per gram of scrap (pCi/g product per pCi/g scrap) (Bq/g product per Bq/g scrap) millirem par year (mrem /y) microseivert per year (pSv/y) 10 millirem per year per picocurie per gram microseivert per year per becquerel per 270.27 (mrem /y per pCi/g) gram (pSv/y per Bq/g) millirem per year per picocurie per microseivert per year per becquerel per 270.27 square centimeter square centimeter (mrem /y per pCi/cm2 ) (pSv/y per Bq/cm2 )
mrem per year per disintegration per microseivert per year per becquerel per 60,000 minute per 100 square centimeters square centimeter l (mrem /y per dpm/100 cm2 ) (pSv/y per Bq/cm2 )
Draft NUREG-1640, Vol.1 Xxii O
L________________________-_____________-
1 INTRODUCTION iO I l (G This report documents the technical basis for establishing a potential U.S. Nuclear Regulatory .
l Commission (NRC) rulemaking that addresses clearance of equipment and materials from nuclear facilities. The report contains descriptions of the analyses used to estimate the potential doses resulting from reuse of equipment and recycle of steel, copper, aluminum, and concrete material following clearance. The analyses were conducted to calculate realistic dose factors for the average member of a criticalgroup for each radionuclide. The analyses were conducted on a probabilistic basis, using parameter value distr'butions as input, to determine distnbutions for specific model results (i.e., concentrations and dose factors). The mean value from a dose factor output distribution represents the average dose to the exposed population, while the highest mean dose factoracross all exposure scenarios designates the criticalgroup for each radionuclide. In addition to the mean values, the 5*, 50*, and 95* percentiles from the distributions are presented and discussed in subsequent sections of the report The U.S. Nuclear Regulatory Commission (NRC) is considering the possibility of revising the criteria for the clearance of material and equipment from nuclear facilities. NRC licensed facilities are currently allowed to release materials and equipment during normal facility operations. These releases are conducted consistent with the acceptable surface contamination ,
levels contained in Regulatory Guide 1.86 and site-specific technical specifications and license conditions. The current regulatory framework suffers from issues of consistency with current risk-based regulatory dose standards and lack of general applicability to a wide range of volumetrically contaminated equipment and material. Over the next few decades, large-scale (V} decontamination and decommissioning (D&D) of NRC-licensed nuclear reactors and other i facilities is expected to generate large quantities of potentially reusable equipment and recyclable l material. The NRC has identified the need for a consistent and health protective regulatory basis to regulate the clearance of such material from regulatory control (NRC 1994a).
l Clearance (unrestricted release from regulatory control) implies that there would be no restrictions on the fate of such equipment and materials based on radiological considerations.
The many possible dispositions of material cleared from regulatory control can be grouped into the following three most likely categories: usable equipment could be reused directly after Jearance (direct reuse); material could be immediately disposed in a landfill (direct disposal) and scrap material could be sold to a scrapyard for recycle (recycle). The potential radiological impacts associated with clearance of equipment and material from regulatory control with respect to each of these categories have been assessed and are presented in this document.
1.1 Purpose and Scope
This report documents analyses of potential radiation doses to members of the public from materials and equipment released by NRC licensed facilities. The analyses are designed to address two principal limitations of current regulatory standards: the lack of risk-based clearance levels and the lack of consistent guidelines for clearing material containing volumetrically distributed radioactivity. The results presented here are intended to support development of 1-1 Draft NUREG-1640, Vol. I
Introduction Section I generic clearance levels that are applicable to all NRC licensed facilities. The methodology developed for these analyses can be applied to case by-case clearance decisions.
{
Clearance ofiron/ steel, aluminum, copper, and concrete is addressed in this report. These '
materials are the most likely to become available for clearance into the public sector and also represent the greatest volume of available material.
The results of these analyses are expressed as radionuclide-specific dose factors that relate the magnitude of radiation dose to the concentration of radioactivity in or on materials or equipment at the time of clearance. The dose factors provide estimates of the radiation dose received by an !
individual over 1 year for a given initial concentration of radioactivity and a specified set of circumstances that make up a hypothetical exposure scenario. The scenarios have been constructed to be as realistic as the quality of the underlying data allow. That is, rather than i
constructing each scenario as a conservative " worst case," the level of conservative bias has been limited to that required for generic application to the situations described in each scenario.
A wide range of exposure scenarios was evaluated to ensure that these dose factors are representative oflikely dispositions of cleared material and equipment. The scenarios comprise a range of reasonably expected reuse, disposal, and recycle activities-from handling cleared scrap through activities during melting and processing, using refined metal products, to disoosing materials in a sanitary or hazardous waste landfill. Impacts associated with residential use of a closed landfill are also assessed.
1.2 Technical Approach O The implications of clearing materials and equipment from licensed nuclear facilities to the public sector presents a complex assessment problem. Clearance from regulatory control implies that many possible groups in the general public could come in contact with these materials and equipment under a wide variety of circumstances. The approach taken in this report is designed to 1) identify a clear assessment endpoint to serve as a basis for clearance criteria that assures adequate protection of the public and 2) provide a comprehensive evaluation of the realistic situations that could result in exposure to groups ofindividuals in the general public.
The design objective for this analysis is to calculate a realistic estimate of the dose factor for the average member of the critical group for each radionuclide. The critical group is defined in ;
10CFR20.1003 as "the group ofindividuals reasonably expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances." For each material evaluated in this andysis, nuclide-specific dose factors are provided for both volumetrically (Bq/g or pCi/g) and surficially (Bq/cm 2or pCi/cm )2 distributed radioactivity. The dose factors are annual individual doses that are normalized to the concentration of radioactivity in cleared material (pSv/y per Bq/g or mrem /y per pCi/g, and pSv/y per Bq/cm2 or mrem /y per pCi/cm2 ),
In order to assure adequate assessment of potential public doses, a wide range of possible scenarios were evaluated to identify the critical group for each radionuclide. The scenarios are Daft NUREG-1640, Vol. 1-2
h
' Section 1 - Introduction based on the flow of radioactivity associated with released material from the point of clearance to i
ultimate disposition and include likely industrial refining processes and use or disposal of I refinery byproducts. This approach provides a basis for clearance criteria that bounds situations and behaviors that can be reasonably expected and avoids unnecessary conservative results.
l . Each exposure scenario was analyzed probabilistically using a unit activity concentration (1 pCi/g) for each radionuclide. Each exposure scenario analysis resulted in a distribution of dose factor estimates for each radionuclide. This was accomplished for a set of scenarios for ,
each material analyzed (steel, copper, aluminum, and concrete) using material-specific )
assumptions.
l 1
!' The mean (average) dose factors from the dose factor distribution in each scenario were ranked ;
L to obtain the highest mean dose factor for each radionuclide within each set of material-specific - l scenarios. The exposed group described in the exposure scenario yielding the highest mean. dose -
factor for each radionuclide was designated as the critical group for that radionuclide. The distribution of dose factors for each critical group is referred to as the critical-group dose factor distribution. Because the mean dose factors are representative of the average members of each l- critical group, the mean critical-group dose factor is sometimes simply referred to as the critical-l group dose factor. In this analysis, there are four critical-group dose factors for each l radionuclide--one for each material: steel, copper, aluminum, and concrete.
, - Figure 1.1 illustrates the relationship between dose factors for a range of exposed groups within the general public and the critical group. This figure displays hypothetical dose factor f distributions (not based on calculated results) for a single radionuclide in various scenarios.
I Many members of the general public will not be in any exposed group, wi.Il not receive any dose, and will have dose factors of zero. The dose factors for each exposed group are comprised of a frequency distribution because of uncertainty in the estimated dose factor. The average member of the critical group is represented by the mean (average) value of the critical group frequency
! distribution, where the critical group is the exposed group with the highest average dose factor for each radionuclide.
l As indicated in Figure 1.1, there are some hypothetical situations or behaviors that could result in dose factors higher than those of the average member of the critical population group. Dose L factors higher than those of the critical group represent situations or behaviors that are not reasonably expected to occur. These situations are not considered in the analyses.
The process of estimating dose factors begins with the development of a set of exposure scenarios for reuse of equipment and recycle of steel, aluminum, copper, and concrete. The intent is to be comprehensive enough to include the situations and behaviors that might reasonably be expected to bring members of the public into contact with cleared material or equipment. Each scenario represents an exposed group with a potential for being designated the critical group. The individual scenarios are described in subsequent chapters for each material evaluated.
1-3 Draft NUREG 1640, Vol. I l-i
introduction Section i O
f
=
g' . ,
= omuExpo-aaroup. ,
Entire Population critical Group Dose Factor Figure 1.1 Relationship of the critical group to other exposed groups A key input parameter for each exposure scenario is the concentration of radioactivity in or on the material that individuals may be exposed to. In the case of direct reuse of equipment, no processing takes place between clearance and the start of the exposure scenario. For recycle scenarios, however, a complex series ofindustrial processes can occur. Recycle of metal involves transportation to a scrap yard, cutting and sizing of scrap, transportation to a refinery, the refinery process itself, and subsequent use of the refined metal product. This process l
produces byproducts such as slag and baghouse dust, which may also contain residual radioactivity. Steel, copper, aluminum, and concrete each undergo a different set ofindustrial )j processes during recycle. These processing steps are addressed by a set of models, called material flow models, that calculate the concentration of residual radioactivity in each material )
and its byproducts at each step. These concentration estimates are input parameters to scenario ]
models.. The material flow models are described in subsequent chapters for each material !
evaluated. )
{
z Both the material flow models and the exposure scenario models are probabilistic. Both the )
input parameters and the resuits calculated by the models are represented by frequency distributions rather than point estimates. This approach follows the general guidance presented Daft NUREG-1640, Vol. 1-4 l
Section 1 Introduction in the Environmental Protection Agency's (EPA) Guiding Principles for Monte Carlo Analysis
-s\
[U (EPA 1997b), NCRP Conunentary Number 14 (NCRP 1996), and 1AEA Safety Series Number 100 (IAEA 1989). These references contain recent guidance on the conduct of probabilistic analyses. They also provide a consistent set of technical terms for describing the various features of the analysis and its results.
All assessments based on model calculations are inhere, dy uncertain. This 'uncertainty arises from several factors, including 1) our ability to adequately model the physical processes involved,2) the degree to which exposure scenarios adequately represent individuals in the desired critical population groups,3) the level of knowledge available to estimate appropriate values for parameters in the model, and 4) the natural variability in various quantities used to estimate parameter values.
Lack of knowledge about an input parameter typically contributes more to the uncertainty of the parameter value than does the natural variability of that parameter.' Even in cases where the natural variability may be significant, quantifying the amount of uncertainty is difficult. This analysis does not attempt to quantify the relative contributions of natural variability and knowledge uncertainty in estimating parameter values.
The analysis presented here does not address uncertainty due to model structure. This has been the subject of other aspects of this dose assessment including external and internal technical reviews and benchmarking selected scenarios against alternative models proposed by other y
assessors (e.g., EPA 1997a).
The analysis uses Monte Carlo techniques to conduct a probabilistic analysis of the material flow l and exposure scenario models. Monte Carlo methods produce a single model result (output) ,
from a set of randomly selected parameter values (inputs). The distribution resulting from numerous iterations of this process are then statistically summarized and characterized. The required number ofiterations depends on the complexity of the model and the statistical quantities to be used. For both the material flow model and the scenario spreadsheets 500 '
iterations were sufficient to produce stable estimates of the mean and the 5*,50*, and 95* l percentiles of the output distribution. This analysis was conducted using models implemented on Excel spreadsheets (Microsoft 1997). Monte Carlo analysis of these spreadsheets was conducted using Crystal Ball @ (Decisioneering 1996) software. Parameter values were sampled using a Latin Hypercube sampling scheme.
Key to the conduct of a probabilistic analysis is the development of frequency distributions for individual parameters in the model. In this analysis all parameters in both the material flow model and the exposure scenarios were characterized as either fixed constants or uncertain parameters with associated frequency distributions. Fixed constants are of three types: physical constants, such as radioactive decay rates; parameters fundamental to the definition of the individual addressed by the scenario; and parameters fundamental to the definition of the scenario itself.
1-5 Draft NUREG-1640, Vol. I
introduction Section 1 The dose assessment addresses individuals representing members of the exposed groups. Some fundamental characteristics of these individuals are considered constants in the model and are not subject to variability or uncertainty. Examples of constants include the biological response to )
radiation or the dose equivalent due to radionuclide intake. Also, certain parameters within each )
scenario are considered constants because they are fundamental to the definition of the scenario.
That is, because they are assumed for purposes of constructing the scenario, they are not subject i to either natural variability or lack of knowledge. Examples include the placement of residences relative to the refinery stack or the location of a drinking-water well relative to a slag storage pile.
For the remaining parameters, frequency distributions have been developed that are appropriate to each scenario and reflect expert judgment regarding the degree to which each parameter is unknown. When available, data reflecting the measured variation of parameters was used in estimating parameter distributions. However, for many parameters, the only available data are not completely representative of the population being assessed. In the absence of acceptable ,
representative data, subjective characterizations of parameter ranges and ' distributions have been j developed based on physical plausibility arguments, the behavior of analogous parameters in other assessments, and expertjudgment. The resulting frequency distributions are necessarily j subjective and should not be considered to represent only natural variability. Conventions for the l assignment of parameter distributions based on the quality of available data are presented in i Appendix B.
In some cases, it is appropriate to combine the variability and uncertainty associated with more than one parameter into a single distribution which can be treated as a lumped parameter. Some complex pathways contain many nuclide-dependent parameters for which data on uncertainty are sparse. To avoid making the analysis overly complex and costly, the uncertainty in these pathways was estimated by choosing key parameters to represent the uncertainty in the entire pathway. For example, in scenarios containing a groundwater pathway. distributions on the absorption coefficient, Ke, contributed most to the total pathway uncertainty. Similarly, for the atmospheric release scenario, the uncertainty in the atmospheric dispersion model was precalculated and assigned to the average x/Q parameter.
Uncertain parameters included in this analysis are assumed to vary independently; that is, covariance among parameters has not been incorporated into the modeling. The potential for strong covariances was evaluated during the parameter characterization process. No strong covariances were identified among the parameters explicitly treated in the analysis. In general, the effect of neglecting covariances is to estimate slightly wider confidence intervals on dose factors.
1.3 Results Presented Results from the material flow models are included in the section for each material. These results consist of values from the calculated distribution of radioactivity concentrations in each -
medium ofinterest (material and industrial byproduct) normalized to unit concentration at the Daft NUREG 1640, Vol. 1-6
o Section l' Introduction lg time of clearance (Bq/g or pCi/g). The mean, median, and 90% confidence interval (5* and 95th
( -percentiles) are presented.
-x The primary results from this analysis are radionuclide-specific dose factors for both ,
wlumetrically and surficially distributed residual radioactivity. The dose factors can be used to l derive clearance levels (Bq/g or Bq/cm2 ) from an appropriate individual dose criterion ( Sv/y). !
The mean, median, and 90% confidence interval (5* and 95'h percentiles) for these dose factors l are presented and discussed. Critical-group dose factors are presented in Section 2 for each
. radionuclide from among all the materials evaluated. Subsequent sections present critical-group
- dose factors for each of the materials evaluated in this analysis: steel, copper, aluminum, and concrete.
i The doses calculated are annual total effective dose equivalents (TEDE), which is the TEDE received during a year of exposure in a given scenario. The TEDE is defined (10CFR20) as the sum of the deep dose equivalent from external exposures and the committed effective dose equivalent (EDE) from internal exposures. Environmental Protection Agency (EPA) dose conversion factors were used for all internal dose calculations and for external exposures where appropriate. The committed EDE from internal exposures was calculated as the 50-year committed EDE from an intake.
As described above, the dose factors are radionuclide-specific. Each radionuclide dose factor is based on a unit radioactivity concentration of a single radionuclide at the time of clearance.
O Mixtures of radionuclides have not been addressed in this report, however, the radionuclide dose factors are additive in the case of a postulated mixture of radionuclides.
This report presents normalized dose factors ( Sv/y per Ba/g or mrem /y per pCi/g, and pSv/y per Sq/cm 2or mrem /y per pCi/cm )2 by which an assumed dose criterion can be divided to give clearance levels for each radionuclide. Comparisons of dose factors and derived clearance levels with several other sources are included in Section 2 (e.g., the International Atomic Energy Agency [IAEA]). An individual dose limit for clearance has not been established. Where needed, a dose criterion of 10 Sv/y (1 mrem /y) was used for purposes of comparison with other criteria. The clearance levels thus calculated are for comparative purposes only.
I i
O l7 Draft NUREG 1640, Vol 1 l
t 2
SUMMARY
AND COMPARISON OF RESULTS O)
\V Dose factors for the average member of radionuclide-specific critical groups were calculated for equipment reuse and material recycle scenarios. The cnticalgroup for each radionuclide for each of the four materials analyzed (steel, copper, aluminum, and concrete) was identified by selecting the highest mean values from the distribution of dose factors generated for each exposure scenario. Dose factors for reuse are based on surticial residual radioactivity, and are independent of material type. Reuse dose factors are less restrictive than recycle dose factors, so they are not discussed further in this section.
Dose factors for recycle are based on volumetric residual radioactivity; surficial dose factors were derived by multiplying the volumetric recycle dose factors by a surface-to-mass ratio.
Over half of the critical groups for recycle of steel, copper, and aluminum describe workers at scrap yards 1 and steelrefineries who transport, handle, and process scrap metal. This is due to a combination of l characteristics of these scenarios: verylittle delay time following clearance, no mixing or melting, and involvement oflarge masses of material. There are also critical groups in scenarios involving handling refineryproducts such as slag and baghouse dust. These scenarios involve radionuclides that concentrate in certain refineryproducts, and they also involve intemal dose pathways. Residual radioactivity in consumer products rarely yields any critical groups.
Transportation and handling of concrete debris are important for concrete for the same reasons that they l are important for the metals. In addition, concrete is commonly used as landfill or disposed ofin municipallandfills, so dose factors for a resident living above buried concrete in a closed landfill were explicitly evaluated andincluded in the concrete criticalgroup determination. This scenario describes the critical group for about 25 radionuclides. In most cases, the critical-group dose factors for these radionuclides are higher for concrete than for the metals.
n The results of this analysis were compared to other clearance criteria. The results compare inconsistently to the acceptable surface contamination levels of Regulatory Guide 1.86. This is probably due to the fact that the Regulatory Guide values are not based on a pathway analysis. The results of this analysis compare more favorably with Environmental Protection Agency (EPA) draft dose factors. In this comparison, the dose factors are almost all within an order of magnitude indicating that the two sets of results can be considered in general agreement. The results of this analysis were also compared with clearance levels published by the European Commission and the Intemational Atomic Energy Agency.
This comparison shows a generallevel of agreement that is closer than with Regulatory Guide 1.86 but not as close as with the EPA draft dose factors, and for those radionuclides where the difference is greater than a factor of 10, the derived clearance levels in this analysis are almost always more restrictive. _
This section presents a summary, comparisca, and briefinterpretation of the results of the overall analysis for clearance of material from Nuclear Regulatory Commission (NRC) licensed facilities. It does not include a summary of the analysis methodology, but does provide a brief discussion of key aspects of the methodology where appropriate in order to explain the patterns of the results. This summary and comparison section contains information that will help interpretation of the results as well as help indicate the significance of them.
The following subsection presents tables containing the critical-group dose factors for all radionuclides, with a briefinterpretation of those dose factors. This is followed by subsections
/7 containing comparisons of the results of this analysis with other available clearance criteria.
2-1 Draft NUREG-1640, Vol.1
4 Summary and Comparison of Results Section 2 i
2.1 Dose Factors for Members of Critical Groups The critical-group dose factors presented in this report represent the mean dose to the group of individuals exposed under the circumstances of the most restrictive scenario (highest calculated dose factor) for each material and radionuclide. The analysis addresses 85 radionuclides and four ;
materials: steel, copper, aluminum, and concrete. Two types of dose factors are calculated:
volumetric (mass-based) and derived surficial. The mass-based dose factors have units of Sv/y per Bq/g (mrem /y per pCi/g) and are calculated using a normalized c6ncentration of 1 pCi/g distributed throughout the volume ofmaterial at the time of release. Derived surficial dose factors are calculated from the mass-based dose factors using a surface-to-mass ratio according to the discussion in Section 4.7. Together, these two sets of dose factors provide the technical basis for formulating a set .of clearance levels for material and equipment to be released from NRC licensed facilities.
Both mass-based and derived surficial dose factors are based on scenarios related to the recycle or disposal of cleared scrap material. The related issue ofequipment cleared for direct reuse is addressed in Section 3.
Table 2.1 lists the mass-based critical-group dose factors for each of the four materials analyzed in this report. Several scenarios were evaluated for each material. The values in Table 2.1 are the highest mean dose factors for each radionuclide from among all exposure scenarios for each material. Each critical-grova dose factor is the mean of a distribution of values calculated for that scenario. Subsequent sections of this report for each material include tabulations of the 5th,50*
and 95* percentiles of these distributions along with the mean values. Results for steel appear in Section 4.9. Those for copper are presented in Section 5.8. Results for aluminum are presented in Section 6.8 and those for concrete are in Section 7.7. A comprehensive tabulation of the results for all steel, copper, aluminum, and concrete scenarios is presented in Appendices F, G, H, and I, respectively.
Specific discussions of the scenarios and critical groups associated with the dose factors in Table 2.1 are presented in subsequent sections of this report. However, there are some general pattems in the results that are discussed in this summary presentation. Most critical groups for recycle of steel, copper, and aluminum describe workers at scrap yards and steel refineries who transport, handle, and process scrap metal or refinery products such as slag and baghouse dust.
Two scenarios involving exposure to cleared scrap account for more than half of the 85 radionuclides for all metals (scrap transportation and scrap handling scenarios).
There are three reasons why the scrap transportation and handling scenarios are important for the l largest number of radionuclides. First, there is minimal delay between clearance of scrap and transporting it to the scrap yard so no significant radioactive decay occurs before the scenario begins for most radionuclides. Consequently, this scenario describes the critical group for many short-lived radionuclides that decay before later scenarios can occur. Second, unprocessed scrap has not yet been subjected to mixing with other materials or chemical partitioning during Draft NUREG-1640, Vol. I 2-2
Section 2 Summary and Comparison of Results
(
ex \ Table 2.1 Mass-based critical-group dose factors for recycle and disposal of cleared materials
) Mean dose factors (pSv/y per Bq/g)
(d Radionuclide Steel Copper Aluminum Concrete H-3 6.4 E-04 5.6E-04 1.8 E-06 8.8E-03 C-14 2.8E-03 1.6E-02 2.6E-04 1.6E+0)
Na-22 4. l E+02 2.2E+02 4.4 E+00 2.2E+02 l P-32 1.3 E-01 1.3 E-01 2.6E-03 1.4 E-01
?$$$$$$$5?5555W45W.
Cl-36 2.7E+00
.SSSW10$?d.Nl&IltW&NSU 5.2E-02 6.8E-04 1.6E+02 K-40 5.2E+01 1.6E+01 3.2E-01 4.7E+01 Ca-41 1.3 E-01 2.0E-03 1.0E-05 4.8E+00 Ca-45 8.2E-02 5.1E-03 3.0E-05 1.8E-02
% . ..l~i S M M M r f 2 2 :L n i % &} moo ~ W4% -;.$dM?.'N QMg]
Mn-54 8.5 E+01 8.5E+01 1.7E+00 8.5 E+01 Fe-55 1.0E-03 9.7E-04 7.3 E-05 3.4E-03 Co-57 3.8E+00 3.8E+00 7.6E-02 6.6E+00 Co.58 9.5E+01 9.5 E+01 1.9E+00 9.6E+01 E N$3Ib Il[d E bE E M 3kE d E 2b1$ M O E 6552.2.K M M j@ $}{.2E M j Q Ni-59 4.5E-04 4.2E-04 2.9E-05 7.4E-03 Co-60 2.5 E+02 2.5 E+02 5.1E+00 2.5 E+02 Ni-63 1.2 E-03 1.1E-03 8.2E-05 1.0E-02 Zn-65 2. l E+02 7.8E+01 1.2E+00 6.0E+01 NSdMU 5d]$@{2.IEM@Q,k[2.'1E+00QyfM4.,lE02))QMQEMMs Se-75 3.6E+0 ! 2.4 E+01 4.9E-01 2.5E+01 Sr-85 4.7E+01 4.7E+01 9.4 E-01 4.7E+01
(~] '
Sr-89 1.2E-01 1.2E-01 2.3 E-03
( 1.4E-01 Sr-90 1.0E+0! 4.3 E-01 1.0E-02 2.2E+00
$MY9IE78D3@ENFY33,E@EM5Mf@3MRTgdQTj Mo-93 1.4E 02 1.lE-02 5.5 E-04 3.8E+01 Nb-93m 8.4E-03 5.9E-03 8.7E-05 2.0E-02 Nb-94 1.6E+02 1.6E+02 3.3 E+00 2.9E+02 Nb-95 7.2E+01 7.2E+01 1.4E+00 7.4 E+01 Fj3X4j95HffgjY;g@lM5fjH,M7;2J@2jMBEj,13 Miff;,[ilMy,E}fiTfM j Tc-99 1.9E-01 2.9E-03 1.8E-04 1.2E+02 Ru-103 4.6E+0 ! 4.6E+01 9.3 E-01 4.7E+01 Ru-106 2.1 E+01 2.1 E+01 4.1E-01 2.1E+01 Ag-108m 1.6E+02 1.6E+02 3.2E+00 1.7E+02 YSW??"S*
Ag-11Om
?5ESSWS$$$DkW?!!55$$55iSWSD 2.8E+02 2.8E+02 5.7E+00 2.8E+02 Sb-124 1.8E+02 1.8E+02 3.6E+00 1.8E+02 1125 2.7E+00 6.5E-02 1.3E-03 3.0E-01 Sb-125 4.1 E+01 4.1 E+01 8.1 E-01 4.1 E+01
$i?ifjhL2]9SM W 3]EM H j,JafiM.@ H73E6 Q. M j @ {ygME,$,, 2 jy ,
I 131 2.5E+01 2.5 E+01 5.0E-01 2.8E+01 Ba-133 2.8E+01 2.8E+0! 5.6E-01 2.8E+01 l Cs-134 6.6E+02 1.6E+02 3.2E+00 1.6E+02 l Cs-137 2.6E+02 6.2E+01 1.2 E+00 6.2E+01 E E N NS$5ffg Mj(({MQE M $jM2,{,53 W g,MJ@pg Wpg]
Ce-144 3.3 E+00 3.3 E+00 6.6E-02 3.3 E+00
[sh Pm 147 1.lE-02 6.8 E-03 5.5E-05 2.8E-02 V
2-3 Draft NUREG-1640, Vol. I i
l l
l l
t
Summary and Comparison of Results Section 2 Table 2.1 Mass-based critical-group dose factors for recycle and disposal of cleared materials Mean dose factors (pSv/y per Bq/g)
Radionuclide Steel Copper Aluminum Concrete Eu 152 1.lE+02 1.lE+02 2.2E+00 1.lE+02 Eu-l54 1.2E+02 1.2E+02 2.4E+00 1.2E+02
$?ESWi$$5$$N$N5$$b?!$555$Sl5?b$$NO.IE$NSh5WS 4.9E-03 3.1E-0l Re-!86 2.5E-01 2.5E-01 Ir-192 1.2E+02 7.1 E+01 1.4 E+00 7.2E+01 Pb-210 1.5 E+02 3.8E+00 7.5 E-01 3.1E+01 Po-210 6.0E+01 1.IE+00 7.4E-02 1.3E+01 NMOEb&CS??lNMOWW&MM.15%WMSUWMMEWOWW$$
Rn-222 8.6E+01 8.6E+01 1.7E+00 1.IE+02 Ra-223 1.8E+01 1.8E+01 3.6E-01 1.9E+01 Ra-224 6. I E+01 6.1 E+01 1.2E+00 7.6E+01 Ac-225 1.4E+01 1.4E+01 2.8 E-01 1.5E+01 E@MMMM EmM3.5 E+00 4ESE 5.3E+02 Ra-226 1.7E+02 1.7E+02 Ac-227 3.4E+02 2.6E+02 1.9E+00 8.4 E+02 Th-227 5.9E+00 5.9E+00 1.2E-01 1.lE+01 Th-228 1.3 E+02 1.3 E+02 2.5E+00 2.7E+02 U$j@,22,8M,?$[jil8]4E3,1j[,lE?[ tjs#]{Ef0lM(([@j],li7Ep0,Qfj25628.9$$ QSly Th-229 4.3 E+02 3.3 E+02 2.3 E+00 1.4 E+03 Th-230 6.5E+01 5.0E+01 3.4E-01 2.2E+02 Pa-231 2.3 E+02 1.8E+02 1.5E+00 2. l E+03 Th-231 1.5E-02 1.5E-02 3.0E-04 3.9E-02 M@j2323ljM,E2.9E+02ML@j(42jyQM1;5Ejo0]TfQQM[1.3E+03MQ 3 Pa-233 1.3 E+01 1.3 E+01 2.6E-01 1.4E+01 U-233 3.4E+01 2.5 E+01 1.8E-01 1.7E+02 Th-234 7.3E-01 7.3 E-01 1.5E-02 7.5E-01 U-234 3.3E+01 2.5E+01 1.7E-01 1.7E+02 EM.QM5SyyMR312E}0lyWjij{@i2dEd1BMMl}FAEWpM13E923yj-Np-237 2.0E+03 1.1 E+02 7.2E-01 7.1 E+04 Pu-238 7. l E+01 5.5E+01 3.8E-01 1.7E+02 U 238 2.9E+01 2.3 E+01 1.56-01 1.3E+02 Pu-239 7.6E+01 5.8E+01 4.0E-01 2.2 E+02 j[jhWS2$72WIQ6E$[$$?Mf5g+0,1X[flMMO{01 Egg @.2E32,J@}{
Pu-241 1.2 E+00 9.4 E-01 6.5E-03 1.7E+01 Am-241 1.lE+02 9.0E+01 5.9E-01 3.3 E+02 Cm-242 4.3 E+00 3.0E+00 2.3E-02 1.1E+01 Pu-242 7.3E+01 5.4E+01 3.8E-01 2. l E+02 RTEUCE2441dDM6Ff543E41 W%fB.9E4@HiM!33.EM@i,7@rM6_E42jfM Note: to convert these values to conventional units (mremly per pCi/g) multiply by 3.70E-03 refining. This means that the initial radionuclide concentration is unchanged. Third, relatively large masses of scrap material are transported in each load so relatively larger amounts of radioactivity are present in this scenario than in most others. Because the scrap transportation scenario involves only the external dose pathway, the radionuclides for which this scenario describes the critical group are all gamma emitters.
Draft NUREG-1640, Vol. I 2-4 O
Section 2 Summary and Comparison of Results Radionuclides with critical groups in slag, dust, and offgas scenarios are those which concentrate i in these materials during the refining process. All of these scenarios include intemal dose pathways: inhalation of dust, inadvertent ingestion, consumption of drinking water or ingestion of garden produce. The radionuclides for which these material-specific scenarios describe critical groups all have relatively long half-lives and are alpha or beta emitters that contribute to I internal dose pathways.
1 Four radionuclides (H-3, C-14, Cl-36, and I-129) have a critical group consisting of members of the general public living in the vicinity of metal refineries exposed to refinery atmospheric releases. These are all volatile radionuclides with no external dose component.
Residual radioactivity in consumer products rarely yields any critical groups. There are four reasons for this. First, the passage of time between clearance and the use of consumer products 'l allows many radionuclides to decay to very small concentrations. Second, the amount of all I metals available from NRC licensed facilities is small compared to the total amounts that are recycled each year. Mixing cleared metals with other metals reduces concentrations of radioactivity in finished products. Third, many radionuclides are partitioned to slag or baghouse dust during refining and do not appear in finished metals. Finally, the relatively small size of consumer products (compared to the amounts of scrap metals encountered by refinery workers) limits the amount of radioactivity to which any individual could be exposed in these scenarios.
In contrast, workers at scrap yards and steel refineries can be exposed to relatively large amounts of cleared steel before mixing, processing, or radioactive decay can take place.
t For most radionuclides, the highest mass-based critical-group dose factor for the three metals are those for steel. Copper and aluminum critical-group dose factors for similar scenarios are smaller than those for steel due to the relatively smaller amounts of copper and aluminum ,
available for clearance compared to the typical capacity of refineries for these metals.
1 Concrete presents a somewhat different case from the metals. Transportation and handling of concrete debris are important for the same reasons that they are important for the metals. In addition, concrete is commonly used as landfill or disposed ofin municipal landfills. Potential doses to a resident living above buried concrete in a closed landfill were explicitly evaluated and included in the concrete critical group determination. This scenario describes the critical group for 28 long-lived, water-soluble radionuclides that contribute to ingestion and drinking water -
pathway doses. In most cases, the critical-group do::e factors for these radionuclides are higher l for concrete than for the metals.
Tele 2.2 lists the derived surficial critical-group dose factors for the four materials analyzed in this report. For all radionuclides, the critical group for the derived surficiel dose factor is the same as for the corresponding mass-based dose factor. The derived surficial dose factors are calculated from the mass-based dose factors using r: surface-to-mass ratio appropriate for each material. Like the rest of this analysis, the derivation of surficial dose factors is a probabilistic 2-5 Draft NUREG 1640, Vol. I
l Summny and Comparison of Risults Srction 2 calculation that takes into account the uncertainty in surface-to-mass ratio. This calculation is discussed in Section 4.7.
Table 2.2 Surficial critical-group dose factors for recycle and disposal of cleared materials Mean dose factors (pSv/y per Bq/cm2 )
Radionuclide Steel Copper Aluminum Concrete H-3 4.8E-04 4.8E-04 6.8E-06 1.9E-04 C-14 2.1E-03 1.4 E-02 1.0E-03 3.7E-01 Na-22 3.2E+02 1.9E+02 1.8E+01 5.2E+00 P-32 9.9E-02 1.IE-01 1.IE-02 3.2E-03 N M S337ddMtjgig85M M EE M E%TE N T.$[U,. % @ @ @ MlM]
l Cl-36 2.1 E+00 4.4E-02 2.8E-03 3.2E+00 K-40 4.0E+01 1.4 E+01 1.3E+00 1.1E+00 Ca-41 9.8E-02 1.7E-03 4.lE-05 1.2E-01 Ca-45 6.1E-02 4.3 E-03 1.2E-04 4.2E-04
, N ,s. &&MiJtM 74jM CQ %% NQ!iMbFPZ$llfi6~M,MQ Mn-54 6.4 E+01 7.3 E+01 6.9E+00 2.0E+00 Fe-55 7.6E-04 8.3E-04 2.9E-04 8.0E-05 Co-57 2.9E+00 3.3 E+00 3.lE-01 1.5E-01 Co-58 7.2E+01 8. I E+01 7.7E+00 2.3 E+00
[55!3$5,9 IQ3-X,8:7E3fy5jQE,9j8EjoGE7M93E%0]Q]2.7EM[;Q ,
Ni-59 3.4 E-04 3.6E-04 1.2E-04 1.8E-04 l Co-60 1.9 E+02 2.2E+02 2. l E+01 6.0E+00 Ni-63 9.IE-04 9.7E-04 3.2E-04 2.4 E-04 Zn-65 1.6E+02 6.7E+01 4.8E+00 1.4E+00 FM.' cum 7777&.,A a -
?FG
.. B%0%a..F.. U..a.i,T .
MD5M 127E41W27.u.~.f,- 6.8E '027.F.
- i. 8..E.+D,.O.mmu ~. x Se-75 2.7E+01 2.1 E+01 2.0E+00 5.9E-01 Sr-85 3.6E+01 4.0E+01 3.8E+00 1.lE+00 Sr-89 8.8E-02 9.9E-02 9.4E-03 3.3E-03 Sr-90 7.5E+00 3.7E-01 4.0E-02 5.5E-02 EffMJ3METTdE6tM{MW230lf61WT6@N8E42TfM?QM6, Ef-02M[
~
Mo-93 1.IE-02 9.5E-03 2.2 E-03 8.5E-01 Nb-93m 6.4E-03 5.0E-03 3.4E-04 , ,. ,,4.'!E-04 Nb-94 1.2E+02 1.4E+02 1.3 E+01 7.38400 Nb-95 5.5E+01 6.2E+01 5.8E+00 1.7E+00 C N N IIN$ M ' M d$5D.IE E.Q Q M $l g f 6j[$4._8E., M M M fgB30,7j$ c Tc-99 1.4E-01 2.5E-03 "'.2 E-04 2.6E+00 Ru-103 3.5E+01 4.0E+01 3.7E+00 1.lE+00 Ru 106 1.6E+01 1.8E+01 1.7E+00 4.9E-01 Ag-108m 1.2E+02 1.4E+02 l .3 E+01 4.3 E+00 I DS.@ 0]9 f d @ @ M l,E j G did, @ }, M @ ji1M @ jTj Q.8@l M $
Ag-11Om 2.1 E+02 2.4E+02 2.3E+01 6.7E+00 Sb-124 1.4E+02 1.5E+02 1.5E+01 4.3 E+00 1-125 2.lE400 5.6E-02 5.3 E-03 7.lE-03 Sb-125 3. l E+01 3.5E+01 3.3 E+00 9.6E-01 E M.dI2$E N E dI8.@ $ 7j3 M i3]E[0il M K fj7]$jd M [ Q Cffl'$ M T;7) l-131 1.9E+01 2.1 E+01 2.0E+00 6.5E-01 Ba-133 2. l E+01 2.4 E+01 2.3 E+00 6.6E-01 Cs-134 4.9E+02 1.4 E+02 1.3 E+01 3.8E+00 Cs 137 2.0E+02 5.3E+01 5.0E+00 1.5E+00 M.a.n&C@~l.l"P5";E211E-iWW%TM3E+00?w?WM_F2.2E.'.U.Pl.?.~ffB.n
- a w.a - ~ kn.,a w~ --- w.a .- n uN2 8.0.~E%2W~E.
Draft NUREG-1640, Vol. I 2-6
I !
! ?1 Section 2 Summary and Comparison of Results i
Table 2.2 Surficial critical-group dose factors for recycle and disposal of cleared materials j
) Mean dose factors (pSv/y per Bq/cm )2
(
Radionuclide Steel Copper Aluminum Concrete Ce-144 2.5 E+00 2.8 E+00 2.7E-01 7.8E-02 Pm 147 8.4E-03 5.8E-03 2.2E-04 4.4 E-04 Eu-152 8.4 E+0! 9.5 E+01 9.0E+00 2.6E+00 Eu-154 9.2 E+01 1.0E+02 9.8E+00 2.9E+00 bbENI5b5MIMMINENE$IMIO.MENE.(QK5MM(62R$5 Re-186 1.9E-01 2.lE-01 2.0E-02 7.2E-03 Ir-192 8.9E+01 6.1 E+01 5.7E+00 1.7E+ 00 Pb-210 1.2E+02 3.3 E+00 3.0E+00 7.4E-01 Po-210 4.4E+01 9.0E-01 2.9E-01 3.1E-01 ,
NEM[ _E M2WOfr#RiQpdgpn'dM M %iLM&GM M M Rn-222 6.5E+01 7.3E+01 6.9E+00 2.5E+00 I Ra-223 1.4E+01 1.5E+01 1.5 E+00 4.5E-01 Ra-224 4.6E+01 5.2E+01 4.9E+00 1.8E+00 ,
Ac-225 1.lE+01 1.2E+01 1.lE+00 3.6E-01
$$$$2IS%SI$$N Ra-226 1.3 E+02
?$$$W0555t?$5$
1.5E+02
$5555$bWS5?b 1.4E+0 ! 1.3 E+0 i
\
Ac-227 2.5E+02 2.3 E+02 7.6E+00 2.0E+01 Th-227 4.4E+00 5.0E+00 4.7E-01 2.6E-01 Th-228 9.6E+01 1. l E+02 1.0E+0 ! 6.3 E+00 EQ1Rp228592Md4_)g%ggig&72E_+0lj[h26.8E+00Q)QE.2.1_E.+001 ,
Th-229 3.3 E+02 2.9E+02 9.2E+00 3.3 E+0 I "x D-230 4.9E+01 4.3E+01 1.4 E+00 5.3E+00
~
Pa-231 1.7E+02 1.6E+02 5.9E+00 5.0E+01
(' #)
Th 231 1.lE-02 1.3 E-02 1.2 E-03 9.2E-04 E[M532EMMM8M$$,{@219Ej01,251[QlM1E,f0]0Mf]ff?g2EM3M Pa-233 1.0E+01 1.lE+01 1.lE+00 3.2E-01 U-233 2.5E+01 2.1 E+01 7.2E-01 3.8E+00 3-234 5.5E-01 6.2E-01 5.9E-02 1.8E-02 U-234 2.5E+01 2.1 E+01 7.0E 01 3.8E+00 MsM$3fffys2[SE}Mjja2Eijd2] LWD _1Eff$y@]QGEEE'EQ2EB6Mj Np-237 1.4E+03 9.4E+01 2.9E+00 1.4 E+03 Pu-238 5.4E+01 4.8E+01 1.5 E+00 4.0E+00 U-238 2.2 E+01 2.0E+01 6.3 E-01 3. l E+00 Pu-239 5.8E+01 5.0E+01 1.6E+00 5.4E+00 2Ty%MFJMQM(([ji((4gBg13MfTQMMM:M40Md Pu-241 9.3 E-01 8.1 E-01 2.6E-02 4.0E-01 Am-241 8.5E+01 7.8E+01 2.4 E+00 8.0E+00 Cm-242 3.2E+00 2.5 E+00 9.1E-02 2.5E-01 Pu-242 5.5E+01 4.6E+01 1.5E+00 5. I E+00
~
EMU 62WJR:BIET4 8E41M7%CEf.2EH1TN?MP2T.5Ef0DETTEflCd7E40MN Note: to convert ihese values to conventional units (mrem /y per pCi/cm2 ) multiply by 3.70E-03 The derived surficial critical group dose factors for steel and copper in Table 2.2 are slightly smaller than the corresponding mass-based dose factors in Table 2.1. This is beccuse thw erage surface-to-mass ratio for typical steel and ccpper objects are slightly less than 1 cm2 8/ . The
<N derived surficial dose factors for aluminum in Table 2.2 are larger than the corresponding mass-l v'
2-7 Draft NUREG-1640. Vol. I J
i l
Summary and Comparison of Results Section 2 based dose factors because the average surface-to mass ratio for typical aluminum objects is )
2 about 4 cm /g. This is largely a consequence of the lower density of aluminum rather than the
{
size and shape of typical aluminum objects. The surface-to-mass ratio for cleared concrete is J significantly smaller, averaging about 0.02 cm2 /g. This reflects the surface-to-mass ratios of large concrete objects such as walls and floor slabs.
2.2 Comparison of Results with Other Clearance Criteria In order to establish a context for interpreting the results of this analysis, they can be compared to
, other clearance criteria. The four available sets of criteria are the existing Regulatory Guide 1.86 surface contamination levels, the draft dose factors of the Environmental Protection Agency (EPA), and the draft clearance levels of the European Commission (EC) and the International l Atomic Energy Agency (IAEA). Each of 6ese sets ofcriteria are intended for slightly different l purposes and are formulated differently. In particular, they are presented in different sets of units. The results of this analysis are comprehensive enough that they can be modified to allow direct comparison with each of the four sets of criteria using the units of each criterion.
2.2.1 Comparison with Regulatory Guide 1.86 Table 2.3 compares the results of this analysis with the average surface contamination levels of Regulatory Guide 1.86 (AEC 1974). The criteria in Regulatory Guide 1.86 are not dose-based and are stated in terms of surficial contamination levels (dpm/100cm2). They do not address volumetric contamination levels and they do not specify the materials to which they apply.
The dose factors developed for this heport do not, by themselves, specify surficial contamination levels for clearance. In order to compare the results of this analysis to the Regulatory Guide 1.86 acceptable contamination levels, it is necessary to assume some annual individual dose criterion.
No annual individual dose level for clearance has been established by the NRC, but for purposes of this comparison a value of 10 pSv/y (1 mrem /y) has been used. While this dose criterion has not been established by regulation for clearance, it is the proposed criterion for the EC and the IAEA. Use of this value allows comparison across all sets of criteria.
The NRC clearance levels in the second column of Table 2.3 represent the results of this analysis expressed in units of dpm/100cm2 . They were calculated from the surficial dose factors in Table 2.2 using Equation 2.1. Consistent with the intended use of Regulatory Guide 1.86, the highest surficial critical-group dose factor from the four materials was used for each radionuclide.
Clearance level = (dose criterion + Dose Factorm)
- 60,000 2.1 where Clearance level -
derived clearance level expressed in Reg. Guide 1.86 units (dpm/100cm2 )
and dose criterion = assumed annual individual dose criterion for clearance (10 pCv/y)
Dose Factor,,w = highest derived surficial dose factor from Table 2.2 ( Sv/y per Bq/cm')
60,000 =
constant for unit conversions
}
Draft NUREG-1640, Vol. I O
2-8
I I
l Section 2 Summary and Comparison of Results
{
l
\
j gy Table 2.3 Comparison of derived NRC surficial clearance levels with Regulatory Guide 1.86 acceptable l ! I contamination levels (across all materials)
\ NRC Reg. Guide 1.86 Ratio Radionuclide (dpm/100 cm )2 (dpm/100 cm2 ) NRC / Reg. Guide 1.86 H-3 1.3 E+08 5000 3.E+04
- C 14 1.6E+05 5000 3.E+01 Na-22 1.9E+02 5000 4.E-02 -
1 P-32 5.4E+05 5000 1.E+02 l
$I6E!$$538ffMS EONEdil@ FEN 7d E65fADA@$3iMM $2EMMI$N$.}2 Cl-36 1.9E+04 5000 4.E+00 K-40 1.5E+03 5000 3.E-01 ,
Ca-41 5.1E+05 5000 1.E+02 l Ca 45 9.9E+05 5000 2.E+02
'l l1?;& M1M F*hQR2. Q@ ~"Z M & M MMMT"lLMG Mn-54 8.2E+02 5000 2.E-01 Fe-55 7.3 E+07 5000 1.E+04 Co-57 1.8E+04 5000 4.E+00
- Co-58 7.4E+02 5000 1.E-01 GM '?L S W E E5 I!$ $ 5 0 W ? ? E 5S&Y5?S$$55$
Ni 59 1.7E+08 5000 S 5.?.$ 05 5$$b 3 E+04 Co-60 2.8E+02 5000 6.E-02 Ni-63 6.2E+07 5000 1.E+04 l Zn-65 3.7E+02 5000 7.E-02 EfV Q C M f F iff 3MF3'A EM375 MyT5000MWR REi'a7.Ey00fj@ f]
Se-7S 2.3 E+03 5000 5.E-01
/ \ Sr-85 1.5E+03 5000 3.E-01
\' / Sr-89 6.0E+05 5000 1.E+02 Sr-90 8.0E+03 1000 8.E+00 EdiET@MjW5 }(([12@,Gj{JU] ((gg39MFME[ SEM$,WffiMj5 Mo-93 7.0E+04 5000 1.E+01 Nb-93m 9.3 E+06 5000 2.E+03 Nb-94 4.3 E+02 5000 9.E-02 Nb-95 9.7E+02 5000 2.E-01 56E[MDMEE9M@2$55d Tc-99 2.3 E+04 3NE.M7E5.$.3 E d d diI N k f 5 E d 5000 5.E+00 Ru-103 1.5E+03 5000 3.E-01 Ru-106 3.4E+03 5000 7.E-01 Ag-108m 4.3 E+02 5000 9.E-02 SE&AgE110m @.8Ed35@EE5Nf6$3M8CMMME 2.5 E+02 5000
$ [ $. @ A N 3 D 5 '
5.E-02 Sb-!24 3.9E+02 5000 8.E-02 I-125 2.8E+04 100 3.E+02 Sb-125 1.7E+03 5000 3.E-01 l
NESElijMN2 32fE @M3W2d .Mfl9MP[.d[N$ E13EM[$$25d l I-131 2.8E+03 1000 3.E+00 Ba-133 2.5 E+03 5000 5.E-01 Cs-134 1.2E+02 5000 2.E-02 Cs-137 3.0E+02 5000 6.E-02 553!ENNEE2 S i M (2!6E M E M $ [Q $}5000fjf[3 ff WJ$j@$Mff((S Ce-144 2.1 E+04 5000 - 4.E+00
/G Pm-147 7.1 E+06 5000 1.E+03
( )
\J 2-9 Draft NUREG-1640, Vol. I
4 Summary and Comparison of Results S:ction 2 Table 2.3 Comparison of derived NRC surficial clearanu levels with Regulatory Guide 1.86 acceptable contamination leveh (across all materials)
NRC Reg. Guide 1.86 Ratio Radionuclide (dpm/100 cm:) (dpm/100 cm )2 NRC / Reg. Cuide 1.86 Eu-152 6.3E+02 5000 1.E-01 Eu 154 5.8E+02 5000 1.E-01 W S U S :iN'5 N 58$NkE W & & $ET$5 W $5ANEN $$$$ M Re- t 86 2.9E+05 5000 6.E+01 Ir192 6.8E+02 5000 1.E-01 Pb-210 S.2E+02 5000 1.E-01 Po-210
~
! AE+03 5000 3.E-01 M3Mman5bEENWaMlan;DM0ffi2LW N3WSYMMlE $WE$3 SCI &Wjj Rn-222 8.2E+02 5000 2.E-01 Ra-223 3.9E+03 1000 4.E+00 Ra-224 1.2E+03 1000 1.E+00 Ac-225 5.0E+03 5000 1.E+00 Ra-226 19N5NM4.0E+02 M 3 M L T.M J /L* f f E 100 MW91EDME 4.E+00 Ac-227 2AE+02 100 2.E+00 Th-227 1.2E+04 50^0 2.E+00 Th-228 5.5E+02 100 6.E+00
$ Is$f.! M 228 K M SfMR$i4EIO23@fy }![!]Liji2f,00MZ$$~( M M [8'.E}003 M P Th-229 1.8E+02 5000 4.E-02 Th-230 1.2 E+03 100 1E+01 Pa-231 3.5 E+02 100 4.E+00 Th-231 4.8 E+06 5000 1.E+03 35$253.M232$y,5j 3[K2.8E402MM M 8 El000] M M SEGfB3M1],$M?j Pa-233 5.3 E+03 100 5.E+01 U-233 2.4E+03 5000 5.E-01 Th-234 P5E+04 5000 2.E+0 i U-234 2.4E+03 5000 5.E-01 E$32.-.jl3 R @ j i ffyQ[2}Et0_3HIM ]5W6]@00Ei@ 3 8- W .EY.E hl Q Q Np-237 4.2E+01 100 4.E-01 Pu-238 1.IE+03 100 1.E+01 U-238 2.7E+03 5000 5.E-01 Pu-239 1.0E+03 100 1.E+01 NTNNf3ESMI 3.53.110N,RHQ,{j !@$M2db0nif=2 92 eft?MMRMj Pu-241 6.4E+04 100 6.E+02 Am-241 7.0E+02 100 7.E+00 Cm-242 1.8E+04 100 2.E+02 Pu-242 1.1E+03 100 1.E+0!
NEEf4F7MT WNi3R@pWN WWM16trmeev W M iY #1W E% M Th; Regulatory Guide 1.86 surface contamination levels are taken from Table 1 of Regulatory Guide 1.86. The ratios of the results of this analysis to the valuec in Regulatory Guide 1.86 v4 over a wide range. Where this ratio is plus-or-minus ha order of magnitude (0.1 to 10) the two sets of criteria can be considered in general agreement. The ratio is greater than 1.0 for 50 out of the 85 radionuclides listed in Table 2.3., indicating that the current analysis produces clearance levels less restrictive than Regulatory Guide 1.86 for these radionuclides. Radionuclides in this group include all the low-energy beta emitters and most of the transuranic radionuclides. For the Draft NUREG-1640, Vol. I 2-10
l l
Section 2 . Summary and Comparison of Results i
p . remaining 35 radionuclides the ratio is less than 1.0, indicating that the results of this analysis produce clearance levels more restrictive than Regulatory Guide 1.86. Radionuclides in this I group include all the highest energy gamma-emitting radionuclides (e.g., Co-60). There are 10 radionuclides for which this analysis produces clearance levels that are more than a factor of 10 more restrictive than Regulatory Guide 1.86.
2.2.2 Comparison with the Environmental Protection Agency The EPA has sponsored an analysis of doses from clearance and recycle of scrap steel ;
(EPA 1997a). The lesults of this analysis are currently available only in draft form. No l clearance levels have yet been established as regulations by the EPA. l The draft EPA dose factors were developed using an approach that is similar to the one presented l in this report. They are based on estimating annual doses to individuals under a variety of scenarios formulated to represent standard industry practices in the United States. Dose factors address only recycle of volumetrically distributed contamination, and results are expressed as normalized annual individual dose factors in units of mrem / year per pCi/g. No annual dcse level is specified. The draft published results are limited to clearance ofiron and steel.
l The EPA results are expressed as normalized annual dose factors, so they can be directly compared to the results in this report. No unit conversions or assumptions regarding an annual p individual dose criterion are required. Table 2.4 presents this comparison for the 40 l l
V radionuclides in common between the two analyses. The NRC dose factors in the second column -
of Table 2.4 are mass-based critical-group dose factors for steel recycle taken from Table 2.1 of this report, expressed in conventional units. The EPA dose factors are taken from Table 7-1 of '
EPA (1997a). Both sets of values are expressed as dose factors, which are inversely proportional to the clearance levels that would likely be embodied in a clearance rule.
The ratio of EPA values to NRC val .es in the fourth column of Table 2.4 shows a much narrower range than the comparison with Regulatory Guide 1.86 clearance levels. For 36 of the l 40 radionuclides in common, this ratio is plus-or-minus an order of magnitude (0.1 to 10) I indicating that the two sets of criteria can be considered in general agreement. Where the ratio is greater than 10 (e.g., C-14, Sr-90), the NRC dose factors from this analysis would indicate a clearance level that is less restrictive than the EPA values. Where the ratio is less than 0.1 (Tc-99, Cs-137), the NRC values would be more restrictive.
i 2.2.3 Comparison with the European Commission The EC has sponsored an analysis of doses from clearance and recycle of scrap steel, copper, and aluminum (EC 1998). The results of this analysis are currently available as recommended clearance levels for member states of the European Union for recycling of metals originating from the dismantling of nuclear facilities.
O 2-11 Draft NUREG-1640, Vol.1
Summary and Comparison of Results Section 2 Table 2.4 Comparison of NRC mass-based steel recycle critical-group dose factors with EPA values ,
NRC EPA Ratio Radionuclide (mrem /y per pCi/g) (mrem /y per pCi/g) EPA / NRC H-3 2.4 E-06 - -
C-14 1.0E-05 8.7.E-04 8.E+01 Na-22 1.5 E+00 - -
P-32 4.8E-04 - -
IBMitTN5f5MW@M?QNQM&.1 S kW ENM M &i ?& %M%%'Wh3NlE4 Cl-36 1.0E-02 - -
K-40 1.9E-01 - -
Ca-41 4.9E-04 - -
Ca-45 3.0E-04 - -
S.. 7y . up.g.; ;r7;q,gygjg
, gS .; .;g,,,n,gggy Mn-54 3.2 E-01 2.0E-01 6.E-01 Fe-55 3.8E-06 6.7E-06 2.E+00 Co-57 1.4 E-02 - -
Co-58 3.5E-01 - -
E$I1" MENS E8M{ME23 381.NEISSEd EEEES2LE$
Ni 59 1.6E-06 4.4 E-06 3.E+00 '
Co-60 9.4E-01 9.0E-01 1.E+00 Ni-63 4.5E-06 1.1E-05 2.E+00 Zn-65 7.9E-01 9.6E-02 1.E-01 e
m-gauMCo-47 h, w M. y ;fd.7 7F Eds
.cf03 gM2
,.,-- - o,,
g;ggg.33-r ' ';;,t.; ggg gig-33,g , y
---s---,
Se-75 1.3 E-01 - -
Sr-85 1.7E-01 - -
Sr-89 4.3 E-04 - -
Sr-90 3.8E-02 1.5E+00 4.E+01 SbNEDI3E[bE75 3 d Wi M EiO3 E EFj fj R@.iAWRWEhij}E[.E! M5$$f8K{MffE@
Mo-93 5.2E-05 5.6E-05 1.E+00 Nb-93m 3.1E-05 - -
Nb-94 6.IE-01 4.7E-01 8.E-01 Nb-95 2.7E-01 - -
Ef53pl$$qfs!@Myf%7F20E15E @fjf((t!E-7ETM[6 ElMF,5ffjE3
' Tc-99 7.0E-04 2.1E-05 3.E-02 Ru-103 1.7E-01 - -
Ru 106 7.6E-02 5.2E-02 7.E-01 Ag-108m 6.0E-01 - -
N[$$$hM {0$ E E$ 31T[5{ M Q IE[ Fi7[EIEEMEf2 Fad E.ECl2333 Ag-l10m 1.0E+00 6.3 E-01 6.E-01 Sb-124 6.7E-01 - -
I-125 1.0E-02 - -
Sb-125 1.5E-01 6.4E-02 4.E-01
- 7. aC.R lux E.s -F.1..2.9. 3 T.W
- "??H3T3FMIT.W.- s. "E' G u 7. 6 9:.73IEUiP""T M. T_IF1%
. V.-
RT.EM. ii6. 7M.a Wm ,
1-131 9.3 E-02 - -
l I
Ba-133 i.0E-01 - -
Cs-134 2.4E+00 2.5E-01 1.E-01 Cs-137 9.5E-01 8.9E-02 9.E-02 mis & W55EE ?NW5$N0.WS5 ?N W I NE E M G E3 LS$$N5%$$
Ce-144 1.2E-02 1.8E-02 1.E+00 Pm 147 4.2 E-05 1.4 E-04 3.E+00 {
Eu-152 4.1E-01 3.4E-01 8.E-01 l l
Draft NUREG-1640, Vol. I 2-12 l
1
Section 2 Summary and Comparison of Results Table 2.4 Comparison of NRC mass-based steel recycle critical-group dose factors with EPA values NRC- EPA Ratio Radionuclide prem/y per pCi/g) (mrem /y per pCi/g) EPA / NRC Eu-l54 4.5E-01 - -
Re-186 9.IE-04 EIMi - -
M Ir-192 - 4.4E-01 - -
Pb-210 5.7E-01 3.1E+00 5.E+00 Po-210 - 2.2E-01 - -
MM%M'EdM&&$f Rn-222 C --
--dh?Md 3.2E-01 - -
Ra-223 6.7E-02 - -
Ra-224 2.3E-01 - -
Ac-225 5.3E-02 - -
MM Ra-226
- & % f >l^ .'
- A -
^
3 L Fw. F Ak?
6.4E-01 6.3 E-01 1.E+00 Ac-227 - 1.3E+00 8.0E+00 ' 6.E+00 Th-227 2.2E-02 - -
Th-228 4.7E-01 1.4E+00 3.E+00 E32FMM3hdFrW.
Th-229 RMME!? FEE if 2 FriH W M 2i?I 12 W G AA M 2EE Eiss 1.eE+00 4.4 E+00 3.E+00 Th-230 2.4E-01 6.4E-01 3.E+00
, Pa-231 8.3E-01 2.5E+00 3.E+00 Th-231 5.5E-05 - -
I. S N . D. E E .@ .My3g@M$$ MMtEMIM7M TjfMM$$$$
Pa-233 4.9E-02 - -
g U-233 1.2E-01 - -
Th-234 1 2.7E-03 - -
U-234 1.2E-01 3.lE-01 3.E+00
[M Np-237 3E .bD$#lsN.EdE$$EfE 3Ei 7.4E+00 1.5E+00 2.E-01 Pu-238 2.6E-01 6.8E-01 3.E+00 U 238 1.lE-01 2.9E-01 3.E+00 Pu-239 2.8E-01 7.3 E-01 3.E+00 35 BEE.W_EAEb Pu-241
$ @ $/.( M 3 $ T. 2E YE3M[85Nd. $$$i @ dl. M.Y8EDE 4.5E-03 1.2E-02 3.E+00 Am-241 4.2E-01 1.2E+00 3.E+00 Cm-242 1.6E-02 - -
Pu-242 2.7E-01 t.9E 31 3.E+00 CXC.@ M 26fM2~ZRMYe%@T29849 W @T W iiiF W 6 4 % T W %2MM1%%SM%2R$
The EC recommended clearance levels were developed using an approach that is similar to the one presented in this report in that they are based on estimating annual doses to individuals under a variety of scenarios formulated to represent standard industry practices. However, they are based on European industry practices rather than the industry in the United States. Clearance levels address both volumetrically and zJicially distributed contamination. The clearance levels are based on an annual individual dose level of 10 pSv/y, and are expressed in units of Bq/g or Bq/cm 2, as appropriate.
d 2-13 Draft NUREG-1640, Vol.1 6
dl/ ___.
Summary and Compcrison of RGsults Section 2 Table 2.5 compares the results in this report to the recommended EC clearance levels for the 62 radionuclides they have in common. The EC clearance levels in Table 2.5 were taken from Table 3-1 of EC (1998), and represent the most restrictive cleuance level for each radionuclide among the three metals analyzed by the EC (steel, copper, and aluminum).
The NRC clearance levels in the Table 2.5 represent the results of this analysis expressed in units ;
of Bq/g or Bq/cm ,2 as appropriate for comparison. Mass-based clearance levels were calculated j from the dose factors in Table 2.1 and surficial clearance levels were calculated from the dose factors in Table 2.2 of this report. In each case, the most restrictive dose factor among the three I metals was used for each radionuclide. Equation 2.2 was used to calculate a clearanc, level for comparison with the EC values.
Clearance level = Dose criterion + Dose Factor 2.2 l where Clearance level = derived clearance level expressed in EC units (Bq/g or Bq/cm2 )
and Dose criterion = annual individual dose criterion (10 pSv/y)
Dose Factor = dose factor from Table 2.1 or 2.2 (pSv/y per Bq/g or pSv/y per Bq/cm2 )
The ratio of the results of this analysis to the EC clearance levels shows a general level of agreement that is closer than with Regulatory Guide 1.86 but not as close as with the draft EPA dose factors. Where this ratio is plus-or-minus an order of magnitude (0.1 to 10) the two sets of criteria can be considered in general agreement. For each radionuclide, the ratio differs between the mass-based and the surficial clearance level. This is because the derived surficial dose factors in this report are calculated from the mass-based dose factors using a surface-to-mass ratio appropriate to each material. The EC surficial clearance levels are based on a set of scenarios different from those used for their mass-based clearance level. A surface-to-mass ratio was not explicitly addressed in the EC analysis. For both mass-based and surficial clearance levels, where the ratio is greater than 1.0 the NRC values would indicate a clearance level that is less restrictive than the EC values. Where the ratio is less than 1.0 the NRC values would be more restrictive. For those radionuclides where the ratio is greater than a factor of 10 different, the derived cleamnce levels in this analysis are more restrictive for all radionuclides except one (H-3).
2.2.4 Comparison with the International Atomic Energy Agency The IAEA has sponsored development of draft clearance levels intended for application to all solid materials irrespective of the disposition of the materials (IAEA 1996). The results of the analysis are currently available only in draft form. Final recommended clearance levels have not yet been established by the IAEA.
Draft NUREG.1640, Vol. I 2-14 O
Section 2 Summary and Comparison of Results Table 2.5 Comparison of derived NRC clearance levels with European Commission values (all metals)
[n\
\
Mass clearance levels NRC Surficial clearance levels EC Ratio NRC EC Ratio Radionuclide (Bq/g) (Bq/g) NRC/EC Rsdionuclide (Bq/cm2 ) (Bq/cm2) NRC/EC H-3 2.E+04 1000 2.E+01 H-3 2.E+04 100000 2.E-01 C-14 6 E+02 100 6.E+00 C-14 7.E+02 1000 7.E-01 Na-22 2.E-02 1 2.E-02 Na-22 3.E-02 10 3.E-03 P-32 8.E+01 - -
P-32 9.E+01 - -
M ir) M G G [(M,,f R E71000 H M lf $ $M[se,SM7$Q(R13fMf05MQig@i$$
Cl-36 4.E+00 10 4.E-01 Cl-36 5.E+00 100 5.E-02 K-40 2.E-01 1 2.E-01 K40 3.E-01 100 3.E-03 Ca-41 8.E+0i - -
Ca-41 1.E+02 - -
Ca-45 1.E+02 1000 1.E-01 Ca-45 2.E+02 100 2.E+00
' @f.y.' ,6f y1[ 'gi@pg;fggtgRR Q Q g Q Q w yl y y fb $ G Q) Q Q Mn-54 1.E-01 1 1.E-01 Mne54 1.E-01 10 1.E-02 Fe-SS 1.E+04 10000 1.E+0v Fe 55 1.E+04 10000 1.E 4 0 Co-57 3.E+00 10 3.E-01 Co-57 3.E+00 100 3.E-02 Co 58 1.E-01 1 1.E 01 Co-58 1.E-01 10 1.E-02
?71tNF5&MIEdEU.T. N.E "d Ni-59
~
- Fe 5 Q T J E 0l M M f tf,G g: M M G Ni-59 2.E+04 10000 2.E+00 3.E+04 10000 3 E+00 Co-60 4.E-02 1 4.E-02 Co-60 5.E-02 10 5.E-03 Ni-63 8.E+03 10000 8.E-01 Ni-63 1.E+04 10000 1.E+00 Zn-65 5.E-02 1 5.E-02 Zn-65 6.E-02 100 6.E-04 HM672MERGECMZ:M Se-75 3.E-01 1 3.E-01 T Cis-60~~EJ6.A+00WP5W8;MME.3,Q Se-75 4.E-01 100 4.E-03 p Sr-85 2.E-01 1 2.E-01 Sr-85 2.E-01 100 2.E-03 t, Sr-89 9.E+01 - -
St-89 1,E+02 - -
Sr-90 1.E+00 10 1.E-01 Sr-90 1.E+00 10 1.E-01 E -N N E.5.W[$3 ffy W 22LE M. My-9.llMMENIM?@b6WQ4E(13]
Mo-93 7.E+02 100 7.E+00 Mo-93 9.E+02 1000 9.E-01 Nb-93m 1.E+03 1000 1.E+00 Nb-93m 2.E+03 10000 2.E-01 Nb-94 6.E-02 1 6.E-02 Nb-94 7.E-02 10 7.E-03 Nb-95 1.E-01 - -
Nb-95 2.E-01 - -
Fi#MiffsfEWAEf2EEI1 BEE!21E_0Ql R2f-95JMQ.E 0RtQf.EMM$g@.E 02]j Tc-99 5.E+0! 100 5.E-01 Tc-99 7.E+0i 1000 7.E-02 Ru-103 2.E-01 - -
Ru-103 3.E-01 - -
j Ru-106 5.E-01 1 5.E-01 Ru-106 6.E-01 10 6.E-02 l Ag 108m 6.E-02 1 6.E-02 Ag 108m 7.E-02 10 7.E-03 {
bAg-110m MNEM N I N E I.D!( 525 4.E-02 4.E-02 dM $ E}NStNM[3NIN/d$dNI50 Ag-110m 4.E-02 1 10 4.E-03 Sb-124 6.E-02 1 6.E-02 Sb-124 6.E-02 10 6.E-03 1125 4.E+00 1 4.E+00 1-125 5.E+00 100 5.E-02 Sb-125 2.E-01 10 2.E-02 Sb-125 3.E-01 100 3.E-03 W W W M $ fffj M13 @@f2.E@gj B f29,y 7 f M Ef3 M M S M )2. 02]IM l l-131 4.E-01 - - 1-131 5.E-01 - -
Ba-133 4.E-01 - -
Ba-133 4.E-01 - -
Cs-134 2.E-02 1 2.C-0~2 Cs-134 2.E-02 10 2.E-03 Cs-137 4.E-02 1 4.E-02 Cs-137 5.E-02 100 5.E-04 PMMf53gME@@H63h?ffE T @ 4_13 9E74.' @0ff E E M F M }]
Ce-144 3.E+00 10 3.E-01 Ce-144 4.E+00 10 4.E-01 Pm-147 9.E+02 10000 9.E-02 Pm-147 1.E+03 1000 1.E+00 2-15 Draft NUREG-1640, Vol.1
)
1 I
Summary and Comparison of Results Section 2 Table 2.5 Comparison of derived NRC clearance levels with European Commission values (all metals)
Mass clearance levels Surficial clearance levels NRC EC Ratio NRC EC Ratio Rada,auclide (Bq/g) (Bq/g) NRC/EC Radionuclide (Bq/cm2 ) (Bq/cm2) NRC/EC Eu-152 9.E-02 1 9.E-02 Eu-152 1.E-01 10 1.E-02 Eu-154 8.E-02 1 8.E-02 Eu-154 1.E-01 10 1.E-02 M M M S M & M IEi M W{p56TfE DM$57fff1MJ@f@$lig5&TJ!iME Re-186 4.E+01 - - Re-186 5.E+01 - -
Ir-192 8.E-02 1 8.E-02 Ir-192 1.E-01 10 1.E-02 Pb-210 7.E-02 1 7.b-02 Pb-210 9.E-02 1 9.E-02 Po-210 2.E-01 I 2.E-01 Po-210 2.E-01 0.1 2.E+00 MWARMMd5 Ell @M*M 2N E YM MIM E Elh M E E E E E M E Rn-222 1.E-01 - - Rn-222 1.E-01 - -
Ra-223 6.E-01 - - Ra-223 6.E-01 - -
Ra-224 2.E-01 - - Ra-224 2.E-01 - -
Ac-225 7.E-01 - - Ac-225 8.E-01 - -
?LWhiwA4.&O0M W#nE6.E-02 W NT@MWW$.YWMM&1%WSN[ Ra-226 7.E-02 0.1 7.E-01 Ra-226 6. F-02 1 Ac-227 3.E-02 - - Ac-227 4.E-02 - -
Th-227 2.E4 00 - - Th-227 2.E+00 - -
Th-228 8.E-02 1 8.E-02 Th-228 9.E-02 0.1 9.E-01 hjlRQ228217gdMiffM2il,f[$ M1.E-015 gyRai2283@lijE-OllM'Q)$ M11n1M Th-229 2.E-02 1 2.E-02 Th-229 3.E-02 0.1 3.E-01 Th-230 2.E-01 1 2.E-01 Th-230 2.E-01 0.1 2.E+00 Pa-231 4.E-02 1 4.E-02 Pa-231 6.E-02 0.1 6.E-01 i Th-231 7.E+02 - - Th-231 8.E+02 M M H f ff02 [ lf l 1 K Z 3 E A 2 ] @h}232]QfMME( IJfjRTf5 -Olf 9.E-01 Pa-233 8.E-01 - - Pa-233 -
U-233 3.E-01 1 3.E-01 U-233 4.E-01 1 4.E-01 Th-234 1.E+01 - - Th-234 2.E+01 - -
U-234 3.E-01 1 3.E-01 U-234 4.E-01 1 4.E-01 l @235hsjM:E-D G 7 f fil E,M3M@ M23FfEj.7@,@M@Mif?fffME2@
Np-237 5.E-03 1 5.E-03 Np-237 7.E-03 0.1 7.E-02 Pt 238 1.E-01 1 1.E-01 Pu-238 2.E-01 0.1 2.E+00 U 238- 3.E-01 1 3.E-01 U-238 4.E-01 1 4.E-01 Pu-239 1.E-01 1 1.E-01 Pu-239 2.E-01 0.1 2.E+00 kWWS$$1$S0?5MWl?
Pu-241 8.E+00 10 8.E-01
$ $ $ ? E N 21E.~A0l ? S ! N W S W % D Pu-241 1.E+01 10 1.E+00 Am-241 9.E-02 1 9.E-02 Am-241 1.E-01 0.1 1.E+00 Cm-242 2.E+00 10 2.E-01 Cm-242 3.E+00 1 3.E+00 Pu-242 1.E-01 1 1.E-01 Pu-242 2.E-01 0.1 2.E+00
!??CiiO244TMiE '01EWWl?WM2.E-O'IN TCs-244'M2'.'E -6fNXS O.lWV2.E400M The draft IAEA clearance levels were developed using an approach that is different from the one presented in this report. Rather than evaluate a set of scenarios representing specific industry practices, the IAEA reviewed several IAEA and other studies that included a variety of scenarios, materials, and radionuclides. In the IAEA approach, radionuclides were sorted into bins representing orders of magnitude of the clearance levels. The logarithmic midpoint of each bin is treated as the single value of the clearance level for all radionuclides in each bin.
Draft NUREG-1640, Vol. I 2-16
l
. SAtion 2 Summary and Comparison of Results The IAEA clearance levels address both volumetrically and surficially distributed contamination.
s The surficial clearance levels are based on a comparative review of mass contamination and surface contamination studies.' Based on this review, the IAEA chose to set surficial clearance l levels in units of Bq/cm 2at the'same numerical value as the mass-based clearance levels in Bq/g.
2 This is equivalent to assuming that all materials have a surface-to-mass ratio of I cm /g. As with the EC, clearance levels are based on an annual individual dose criterion of 10 pSv/y.
Table 2.6 compares the results in this analysis to the draft IAEA clearance levels for the 48 radionuclides they have in common. The IAEA clearance levels were taken from Table I of IAEA (1996).
The NRC clearance levels in Table 2.6 are the results of this analysis expressed in units of Bq/g -
or Bq/cm 2, as appropriate. Mass-based clearance levels were calculated from the dose factors in Table 2.1 and surficial clearance levels were calculated form the dose factors in Table 2.2 of this .
report. In each case, the most restrictive dose factor among the four materials analyzed was used for each radionuclide, because the IAEA clearance levels are intended to be applied to all solid ,
materials._ Equation 2.2 was used to calculate a clearance level for comparison with the IAEA _ -
values.
The ratio of NRC derived clearance levels to IAEA clearance levels shows a degree of agreement j that is similar to that for the EC values. Where this ratio is plus-or-minus an order of magnitude
(" (0.1 to 10) the two sets of criteria can be considered in general agreement. For both mass-based Q] and surficial clearance levels, where the ratio is greater than 1.0 the NRC values indicate a clearance level that is less restrictive than the EC values. Where the ratio is less than 1.0 the NRC values are more restrictive. Similar to the EC comparison, for those radionuclides where the ratio is greater than a factor of 10 different, the derived clearance levels in this analysis are more restrictive for all radionuclides except one (Fe-55).
2-17 Draft NUREG-1640, Vol.1 L
L
Summary and Comparison of Results Section 2 Table 2.6 Comparison of derived NRC clearance levels with IAEA values (all materials)
Mass clearance levels Surficial clearance levels NRC IAEA Ratio NRC IAEA Ratio Radionuclide (Bq/g) (Bq/g) NRC / IAEA Radionuclide (Bq/cm2 ) (Bq/cm2 ) NRC / IAEA H-3 1.lE+03 3000 4.E-01 H-3 2. l E+04 3000 7.E+00 C-l4 6.3 E-01 300 2.E-03 C-14 2.7E+01 300 9.E-02 Na-22 2.4E-02 - - Na-22 3.2E-02 - -
P-32 7.3E+01 300 2.E-01 P-32 9.0E+01 300 3.E-01 M & 2 2 M.W M %M,M 9?h 4'.5 M?.8N}'$M$RbiW:M
- M ai;n]$$$
Cl-36 6.3 E-02 300 2.E-04 Cl-36 3.1 E+00 300 1.E-02 K-40 1.9E-01 - - K-40 2.5E-01 - -
Ca-41 2. l E+00 - - Ca-41 8.5 E+01 - -
Ca-45 1.2E+02 3000 4.E-02 Ca-45 1.6E+02 3000 5.E-02 WGEMST%CMWscua., __ . __ men , .ny_sa.wnnuswcyB Mn-54 1.2E-01 0.3 4.E-01 Mn-54 1.4E-01 0.3 5.E-01 Fe-55 2.9E+03 300 1.E+01 Fe-55 1.2E+04 300 4 c.+01 Co-57 1.5E+00 30 5.E-02 Co-57 3.1 E+00 30 1.E-01 Co-58 1.0E-01 3 3.E-02 Co-58 1.2E-01 3 . 4.E-02 MNS97591 GEE 02WF33M97Efi3Mi 22Fjj@~]f.0F41Eg7fj$Q3i(0]2 Ni-59 1.4 E+03 - -
Ni-59 2.8E+04 - -
Co-60 3.9E-02 0.3 1.E-01 Co-60 4.6E-02 0.3 2.E-01 Ni-63 1.0E+03 3000 3.E-01 Ni-63 1.0E+04 3000 3.E+00 Zn-65 4.7E-02 0.3 2.E-01 Zn-65 6.2E-02 0.3 2.E-01 HC@JETI3.3E40077-?Pm #p,M XCR7EM7Ef00MjB]i3M1dE Se-75 2.8E-01 - -
Se-75 3.8E-01 - -
Sr-85 2.lE-01 - -
Sr-85 2.5E-01 - -
Sr-89 7.0E+01 300 2.E-01 Sr-89 1.0E+02 300 3.E-01 Sr-90 9.8E-01 3 3.E-01 Sr-90 1.3 E+00 3 4.E-01
$3&91E?iMEMEjijfRjlW4R5 3[jJ.jp_1]F$3,3EMG??RDFEM@2Mf Mo-93 2.6E-01 - -
Mo-93 1.2E+01 - -
Nb-93m 4.9E+02 - -
Nb-93m 1.6E+03 - -
Nb-94 3.4 E-02 0.3 1.E-01 Nb-94 7.2E-02 0.3 2.E-01 Nb-95 1.4 E-01 - -
Nb-95 1.6E-01 - -
~d1 N IN b5$ M N M E E E I 552 ibid n 2ZZ@yyyElI6@gfMfM j/y M B"fn$
f Tc-99 8.4E-02 300 3.E-04 Tc-99 3.9E+00 300 1.E-02 Ru-103 2.lE-01 - -
Ru-103 2.5E-01 - -
Ru-106 4.8E-01 3 2.E-01 Ru-106 5.7E-01 3 2.E-01 Ag-108m 5.8E-02 - -
Ag-108m 7.2E-02 - -
R @ ,G E W @ @ f[@l)3007{Ef @ @ E F C M 097g 2 jj!.E M f@ E @ n.f6 7[1 M._12$
Ag-110m 3.5E-02 0.3 1.E-01 Ag-110m 4.1E-02 0.3 1.E-01 Sb-124 5.5 E-02 0.3 2.E-01 Sb-124 6.5E-02 0.3 2.E-01 1-125 3.7E+00 30 1.E-01 1-125 4.7E+00 30 2.E-01 Sb-125 2.5E-01 - -
Sb-125 2.9E-01 - -
E i. 5I N E 3. @HQjEH1M$ WI129EM0ENTMG3.035pjdn03W I-131 3.6E-01 3 1.E-01 1-131 4.7E-01 3 2.E-01 Ba-133 3.6E-01 - -
Ba-133 4.2E-01 - -
Cs-134 1.5E-02 0.3 5.E-02 Cs-134 2.0E-02 0.3 7.E-02 Cs-137 3.9E-02 0.3 1.E-01 Cs-137 5.lE-02 0.3 2.E-01 E CE W M 6J)E}Y Q Ef E M E[1 2 1 5 'ECE @ 3lE[ M f06J$f G 5 3 Effi 2 3.5]
Ce-144 3.0E+00 30 1.E-01 Ce-144 3.6E+00 30 1.E-01 Pm-147 3.6E+02 3000 1.E-01 Pm-147 1.2E+03 3000 4.E-01 Draft NUREG-1640, Vol. I 2-18
-_ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ - _ _ _ _ - _ _ _ _ _ _ - _ _ _ _ - _ - _ _ _ _ _ - _ _ _ _ _ _ a
f Secti:n 2 Summry and Comp 1rison of Results i
g Table 2.6 Comparison of derived NRC clearance levels with IAEA values (all materials) ll \ 1 Mass clearance levels Surficial clearance levels 1
l U) NRC IAEA Ratio NRC IAEA Ratio l Radionuclide (Bq/g) (Bq/g) NRC / IAEA Radionuclide (Bq/cm2 ) (Bq/cm2 ) NRC / IAEA ;
i Eu-152 9.0E-02 0.3 3.E-01 Eu-152 1.lE-01 0.3 4.E-01 j i Eu-154 8.2E-02 - -
Eu-154 9.6E-02 - -
i Re-186 3.3E+0 i MW3IS-MES E Re-186 W 5111NMS$ FEE E M "sSIfM I 4.8E41 - - l Ir-192 8.4E-02 3 3.E-02 fr 192 1.lE-01 3 4.E-02 Pb 210 6.5E-02 0.3 2.E-01 Pb-210 8.7E-02 0.3 3.E-01 Po-210 1.7E-Ol 3 6.E-02 Po-210 2.3 E-01 3 8.E-02
- . _; (;31
- g ppy 3 g-_ _
3g Rn-222 9.5E-02 - -
Rn-222 1.4E-01 - -
Ra-223 5.2E-01 - -
Ra-223 6.5E 01 - -
Ra-224 1.3E-01 - -
Ra-224 1.9E-01 - -
Ac-225 6.5E-01 - -
Ac-225 8.3E 01 - -
1 M ;p3 s g g y
- 3 g 'O g g 7'3Q?jt Na--Q8' 8HI6%@WM.@?i~ $ $@ I Ra-226 1.9E-02 0.3 6.E-02 Ra-226 6.7E-02 0.3 2.E-01 :
Ac-227 1.2E-02 - -
Ac-227 3.9E-02 - - l Th-227 9.0E-01 - -
Th-227 2.0E+00 - -
Th-228 3.7E-02 0.3 1.E-01 Th-228 9.2E-02 0.3 3.E-01 l S;(n}228Eo9Me.[lByll2Ni?@50.3j@Hipi[4.E-06f {E1Q228Eyllj.4E0ff.[jQOg8Q@{5Fro l,fy Th-229 7.4E-03 - -
Th-229 3. l E-02 - -
Th-230 4.5E-02 0.3 2.E-01 Th-230 2.0E-01 0.3 7.E-01 Pa 231 4.8E-03 - -
Pa-231 5.9E-02 - -
f Th-231 2.5E+02 - -
Th-231 7.9E+02 t, ]j b
ES2327flR7.6E-032f%d-]3M3_g3 M23L23?T4.'6E 02,y[10 33ryf2l.E-O{M Pa-233 7.4E-01 - -
Pa-233 8.9E-01 - -
U-233 6.0E-02 - -
U-233 3.9E-01 - -
Th-234 1.3E+01 - -
Th-234 1.6E+01 - -
U 234 6.0E-02 0.3 2.E-01 U-234 4.0E-01 0.3 1.E+00 E 3 A E Yt M E .7 03 FJ@* i2dE y,12] js@ffg63XI.Mf,ETJ[j0])I@@3%3.E@R Np-237 1.4E-04 0.3 5.E-04 Np-237 7.0E-03 0.3 2.E-02 Pu 238 5.8E-02 - -
Pu-238 1.8E-01 - -
U-238 7.7E-02 0.3 3.E-01 U-238 4.5E-01 0.3 1.E+00 Pu-239 4.5E-02 0.3 1.E-01 Pu-239 1.7E-01 0.3 6.E-01 MNMIES.[Miaj0G[i M 23nM E! W F N 3 M Rl.F_y0WQ Pu-241 5.8E-Ol 30 2.E-02 Pu-241 1.lE+01 30 4.E-01 Am-241 3.0E-02 0.3 1.E-01 Am-241 1.2E-01 0.3 4.E-01 Cm-242 9.4E-01 - -
Cm-242 3 lE+00 - -
Pu-242 4.7E-02 - -
Pu-242 1.8E-01 - -
"""'""""'WMT031L"7!352.841WWSW'@Fi9.lB41~fFIMfE6.fMTQDibl3Fi l\p)
\s t
2-19 Draft NUREG-1640, Vol.1
3 EVALUATION OF DIRECT REUSE OF EQUIPMENT (3J s
An analysis of the direct reuse of cleared equipment is presented. This analysis differs from recycle scenariosin th'ee ways: (1) surficial contamination is assumed, rather than volumetric, (2) there is no processing of the equipment prior to use, and (3) the analysis is independent of equipment material.
A single scenario involving the driver of a cleared truck was analyzed, as this scenario was determined to bound all other equipment reuse scenarios. The evaluation resulted in realistic estimates of l
radionuclide-specific dose factors for an average member of the exposed group. The analysis was \
conducted on a probabilistic basis, and the mean of the dose factor distribution was selected to I represent the dose to an average member of the exposed group.
Mean dose factors range from a high of 1.7E+02 pSv& per Bq/cm* (0.6 mrem & perpCi/cm') for Th-229 to a low of 1E-05 pSv&per Bq/cm (4E-08 mrem & perpCi/cm ) for H-3. The high mean dose factor of \
Th-229 (and also Ac-227 and Th-232) is attributed to the inhalation exposure pathway and a relatively high inhalation dose conversion factor. Otherhigh reuse scenario mean dose factors (e.g., for Co-60 and Ag-110m) result from the extemclexposure pathway. Approximately one-third of the mean dose l factors are greater than 10pSv4perBq/cm'(0.04 mrem &perpCi/cm'), one-third are between i 0.01-10 pSv/y per Bq/cm (4E-05-0.04 miem/yperpCi/cm ), and the remaining one-thid are less than 0.01 pSv/y per Bq/cm' (4E-05 mrem & per pCi/cm ). These equipment reuse dose factors are less restrictive than comparable recycle dose factors describedlaterin the report. '
}
(
The purpose of this section is to present an evaluation of the limiting dose consequences of C)T
(, immediate reuse of cleared equipment with residual radioactivity on its surface (direct reuse of l equipment). As with recycle, direct reuse of equipment could result in an infinite number of l exposure scenarios, from the reuse ofitems as small as hand tools, to very large items such as
{
trucks or other vehicles. Reuse could also involve the one-time use of a piece ofequipment for a i very short duration, or long-term use for a year or more. Scenarios involving reuse ofland or a building are outside the scope of this evaluation, as they are addressed elsewhere (i.e.,
NUREG/CR-5512 [ Kennedy and Strenge 1992) or NUREG-1500 [NRC 1994b]).
The analysis of equipment reuse differs from the analysis of recycle (Section 4) primarily in three j respects: surficial contamination is assumed, rather than volumetric; there is no processing of the equipment after clearance from the licensed facility; and the analysis is independent of l equipment material. Also, the goal of the equipment reuse scenario analysis is different than that of the recycle analyses described in later sections of this report. The goal of the reuse scenario l analysis is to realistically analyze a bounding scenario for reuse of cleared equipment. Thus the conceptual setting of the reuse exposure situation represents conditions of reuse that are judged I to be bounding for all equipment reuse scenarios, however the parameter values used to analyze the scenario are realistically chosen.
t I
The following sections contain a description of equipment reuse scenarios, including the bounding scenario analyzed. This includes a description of the exposure pathways included in A the bounding scenario evaluation and the equations used to analyze the doses for the scenario.
b 3-1 Draft NUREG-1640
Evaluation of Direct Reuse of Equipment Section 3 Finally, a discussion of the probabilistic parameter values used in the evaluation, a listing of selected results from the distribution of dose factors from the equipment reuse scenario analysis, and a comparison of those results to the recycle analysis results are included. l l
3.1 Direct Reuse Scenario Description I In order to address the possible range of unrestricted reuse scenarios, the types ofitems likely to i be reused were identified. These items fall into the following categories:
- small hand tools and other hand-held items such as drills, saws, and buffers e electrical items such as motors, pumps, and generators office equipment (although these items should not be contaminated) construction equipment such as scaffolding, noise or dust-control barriers, wheelbarrows
- large equipment such as trucks and other vehicles.
An initial qualitative screening resulted in the judgment that work related use of a reused item would result in much longer potential durations of exposure, with other factors being the same, as for home or residential reuse. Home use of an item from the laboratory or industrial setting of a Nuclear Regulatory Commission (NRC) licensee would likely be for an intermittent or short duration, as opposed to the possible full-day, work-related reuse of an item, over a period of time equivalent to a full workyear. Therefore, work-related settings were emphasized.
It is likely that equipment that is cleared for direct reuse will contain surfi,:ial contamination rather than volumetric contamination, thus, only surficial contamination reuse scenarios were analyzed. In screening analyses conducted for this assessment, two scenarios involving reuse of equipment containing surficial contamination were analyzed in detail. Of these two scenarios, only the scenario resulting in consistently higher dose factors for all radionuclides is included in this report. This scenario was developed to represent the critical group scenario for all potential scenarios involving surficial contamination, including hand tools and other equipment. The critical group scenario consists of the reuse of a large piece of equipment (a truck). This bounding scenario is the reuse scenario discussed in the remainder of this section.
The critical group in this scenario is the group ofindividuals that drive trucks that have been cleared from NRC licensed facilities. The individual receptor in the reuse scenario is a truck driver. This individual is exposed externally to radiation from residual radioactivity on the inside of the truck cab, as well as internally to contamination resuspended from the surface and to inadvertent ingestion of surface radioactivity. The dose measure is the total effective dose equivalent (TEDE), which is defined in 10CFR20.1003 as the sum of the (extemal) deep-dose equivalent and the (internal) committed effective dose equivalent (EDE).
Based on assumed good health physics ptactices at NRC licensed facilities, removable surface contamination has been removed during decontamination procedures prior to final survey and Draft NUREG-1640 3-2 O
f l
- Section 3 - Evaluation of Direct Reuse of Equipment clearance. Furthermore, to simplify the analysis, it is assumed tl.at the residual surface
- radioactivity is uniformly distributed on the interior surface of the truck cab.
3 There are three exposure pathways included in the evaluation of the reuse scenario: . external -
radiation exposure, inhalation exposure, and secondary ingestion exposure. External exposure to j . penetrating radiation would result from radionuclides on the inside surface of the truck cab. The i
inhalation pathway is included because a worker inside the truck cab could inhale contamination that has been resuspended into the air. This resuspension could either be caused by air flowing through the cab of the truck or other mechanical disturbance of residual surface radioactivity.
L The third exposure pathway is secondray Egstion. Secondary ingestion refers to the ingestion of removable residual surface radior.ctivhy ; de the truck cab after transfer to hands, food, or other items entering the mouth. Evi o mort 4an inhalation of resuspended contamination, secondary ingestion is a poorly defined p:4way that is not easily calculated by a detailed l description of the mechanisms involved. The dose from this exposure pathway is calculated using an approach similar to the inhalation pathway, where the residual surface radioactivity is related to intake by means of a lumped parameter that accounts for the combined effects of several poorly understood processes. The lumped parameter represents the effective transfer rate,
- which is a parameter that estimates the area of contamination that is ingested per hour (in units of -
area / time).
3.2 Exposure Pathways s The modeled concentration of radioactive material on the surface of the truck cab is a unit concentration (1 pCi/cm2 ) at the time of clearance from the nuclear facility. The following equations were evaluated separately for each radionuclide in the analysis. Therefore, parameters such as concentration, decay factors, decay constants, and dose conversion factors are not explicitly subscripted for each radionuclide.
' The surface concentration at ne time the reuse begins is calculated by Equation 3.1. This ;
concentration is slightly les; dan the unit concentration assumed at the time of clearance. l r4 Coy -
C,, e 3.1 where C, = surface concentration on the reused item at the time the scenario begins (pCi/cm2 )
and C. = surface concentration on the reused item at the time of clearance (pCi/cm2 )
A, = radioactive decay constant (dd) t, = delay time from clearance ofitem from nuclear facility to time scenario begins (d) ;
I The annual dose for the reuse scenario is calculated for the 1-year period immediately following clearance and the short delay time, t,. The bounding reuse scenario involves the use of a single i truck over an entire 1-year period, so radioactive decay over that period is appropriate to incorporate. This is done by the use of a decay factor that consists of the integrated decay over the time from beginning to end of use, as shown in Equation 3.2.
3-3 Draft NUREG 1640 1
t
Evaluation of Direct Reuse of Equipment Section 3 DK = I 3.2 where DK = decay factor for radioactive decay over period of reuse (unitless) and A, = radioactive decay constant (dd )
=
t,, duration of use ofitem (d)
The decay factor is applied to each pathway dose in Equations 3.3,3.4, and 3.5; each pathway dose is multiplied by the decay factor. The TEDE for the scenario is then calculated by the addition of the decay-corrected doses from the external, inhalation, and secondary ingestion j exposure pathways. The mathematical equations for calculating the doses for each of the three l exposure pathways in this scenario are discussed in the following three subsections.
)
1 3.2.1 External Exposure The dose from external exposure to penetrating radiation from residual surface radioactivity is calculated using Equation 3.3.
D, = C o.,
- GF . t, = t,, DK 3.3 1
D. = EDE due to external exposure (mrem /y) and C. t
= surface concentration on the reused item at the time the scenario begins (pCi/cm2 )
GF = geometry factor for the scenario (mrem /h per pCi/cm2) to = daily number of hours of exposure for the scenario (h/d) t,, = annual number of days of exposure for the scenario (d'y)
DK = decay factor for radioactive decay over period of reuse (unitiess) 3.2.2 inhalation Exposure The dose due to the inhalation of resuspended residual surface radioactivity is calculated t sing Equation 3.4.
D;,,, = Co,,
- RF,, = BR
- DF;,y t,,
- t,, DK
- 1E+06 3.4 where Da = EDE due to inhalation (mrem /y) and C, #
= surface concentration on the reused item at the time the scenario begins (pCi/cm2 )
RF, = resuspension factor for residual surface radioactivity (cmd )
BR = breathing rate for moderate physical activity (m'/h)
DF ion = inhalation dose factor (mrem /pCi intake)
Draft NUREG 1640 3-4
(
l Section 3 Evaluition of Direct Reuse of Equipment j- to =
daily number of hours of exposure for the scenario (h/d)
=
{ t, y annual number of days of exposure for the scenario (d/y) i ( DX lE+06
=
=
decay factor for radioactive decay over period of reuse (unitiess) unit conversior. J actor (cm'/m')
I 3.2.3 Secondary ingestion Exposure The dose due to secondary ingestion of removable residual surface radioactivity inside the truck cab after transfer to hands, food, or other items entering the mouth is calculated using Equation 3.5 D;,,, = Cy
- IR,
- DF;,,,
- t, = t,
- DK 3.5 where D., =
EDE due to secondary ingestion (mrem /y) and Co., =
surface concentration on the reused item at the time the scenario begins (pCi/cm2 )
IR, =
effective transfer rate for ingestion of residual surface radioactivity (cm2 /h)
DF,, = ingestion dose factor (mrem /pCi intake) to -
daily number of hours of exposure for the scenario (h/d)
=
t, y annual number of days of exposure for the scenario (dly)
DK =
decay factor for radioactive decay over period of reuse (unitiess)
-%J(m) 3.2.4 Total Dose from Equipment Reuse The total dose from the reuse scenario is the sum of the three exposure pathway doses (external, inhalation, and secondary ingestion). This is calculated using Equation 3.6 D r- D, + Da +D,,,, 3.6 Where Dr = TEDE for the scenario and D. = EDE due to external exposure (mrem /y)
D. = EDE due to inhalation (mrem /y)
D., = EDE due to secondary ingestion (mrem /y) 3.3 Discussion of Models and Parameter Values This section provides a basis for choosing values for key parameter values and distributions used in this analysis. The equipment reuse scenario was analyzed probabilistically, resulting in a distribution of dose factors for each radionuclide.
Values for the decay factor, DK, were calculated by integrating the radioactive decay over a period of 1 year, which is the duration of use of the reused item, to . Values for each radioactive
( )
3-5 DraftNUREG 1640
Evaluation of Direct Reuse of Equipment Section 3 decay constant,( used in the calculation were taken from Federal Guidance Report 11 (EPA 1988). All equipment that is cleared and reused is assumed to be initially taken to a distribution center (e.g., surplus equipruent broker). A time period of 4 days for handling and transport of the material prior to reuse is assumed, as well as an additional 7 day storage period at the distribution center (see Section 4). Thus, a value of 11 d (I 50%) is used for t,. Finally, a range of I h/d to 8 h/d was used for tx ,, a fixed value of 250 d/y is used for t y,, for both the extemal and internal exposure pathways.
The other parameters used are each unique to a given exposure pathway, so the remainder of the discussion is arranged by exposure pathway.
3.3.1 Extemal Pathway External dose models typically use generic geometrical shapes (e.g., discs, cylinders, and spheres) to represent a variety of potential items (e.g., O'Donnell et al.1978, IAEA 1992, Chen 1993). Radionuclide-specific values for the geometry factor (GF) used for the external exposure pathway evaluation are based on shielding calculations using the computer code MCNP. Values are listed in Appendix C (GF #12). The GF values were calculated assuming the residual surface radioactivity is on the inside surface of a hollow sphere, with the receptor at the center of the sphere. External geometry factors include the dose contributions of progeny as described in Appendix E.
This analysis uses a hollow sphere to represent a vehicle. In this geometry, the receptor is inside the sphere and all the residual radioactivity is assumed to be on the inside surface of the sphere.
The external geometry factors used in this evaluation do not include potential dose contributions from beta particles. This could be a nonconservative aspect of the external dose for some radionuclides, as it is conceivable that the driver of a truck with interior residual surface radioactivity could receive a skin dose from beta particles emitted from some radionuclides.
However, this dose contribution would likely be insignificant for most radionuclides and very small, even for the radionuclides with the most energetic beta emissions. This is largely because in order to receive a significant skin dose to the most likely exposed part of the body (hands), the hands of the driver in this scenario would have to be in contact with the contaminated surface for a significant length of time. The steering wheel of the truck is the only potentially contaminated surface of the truck cab that a driver's hands would be in contact with for more than a very brief time. )
3.3.2 inhalation Pathway The inhalation dose model used in this study is essentially the same as that used in several other similar studies (IAEA 1970, IAEA 1992, Kennedy and Strenge 1992, Chen 1993). An exception is one of the earliest recycle assessments (O'Donnell et al.1978), which did not include resuspension of residual surface radioactivity as an exposure pathway.
Draft NUREG-1640 3-6 O
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l
E i<
L )
Section 3 ' Evaluation of Direct Reuse of Equipment i
I Table 3.1 Representative reported indoor resuspension data and recommended values l Reference Resuspension factor or range -
Comments g% Barnes(1959) d 4E-5 m (confined space) Reported for " dusty operations"; 104m d 2E-6 md (open air) recommended for most laboratory work.
Stewart (1964) lE-6 m d(quiescent conditions) Notes that excessively high particulate resuspension IE-5-lE-4 m d(" operational" values indoors are likely to indicate some degree of l conditions) inefficiency in the ventilation system.
l Bmnskill(1964) 2E-4-4E-3 md Measured in small rooms with various types of l personnel movement, including introduction of ll loose contamination on coveralls. Lower l' recommended values avere measured for a large area of" loose" contamination on concrete;"much smaller" values were found for linoleum floor. l l Jones and Pond 2E-8-5E-5 md Estimated that 10-20% of total airbome I d
! (1964) SE-5 m (recommended for worst radioactivity was respirable. Suggested that i practical conditions) recommended value could be an order of magnitude lower for average conditions.
l Dunster(1964) 2E-6-4E-5 md Highest values from digging through dusty building ;
- 2E-6 md(recorr. mended safe value for rubble and in an enclosed and unventilated space. >
l long-term use)
Spangler and Willis 4E 'S md (derived) This value is calculated using equation for (1964) equilibrium airborne concentration in a small room from a surface concentration and recommended '
values appropriate for calculating 40 hr maximum permissible concentration (MPC) levels.
d l Healy (1971) 2.1 E-7-1.0 E-3 m (derived) This value is calculated using the equation for
!IO airbome concentration, assuming ventilation rate for a reasonably tight 28 m2 x2.4 m room.
Gibson and 2E-6-4E 5 md The lower value was used in original calculation of
, Wrixom (1979) derived working limits (DWL) for active area l surfaces and might be inappropriate for widespread l contamination on dusty surfaces. The higher value was obtained from measurements in a confmed l space and is suggested for general use.
IAEA (1970) 2E-6-3E-3 md Recommended value is suggested as appropriate for d
SE-5 m (recommended) general conditions of contamination on surfaces.
Because of confounding factors, this effectively reduces the recommended value by 2.5x for use in l calculating DWL values.
d
( Kennedy et al. 2.5E-5 m (derived) This value is calculated using the equation for (1981) airborne concentration, assuming ventilation rate of an open transport truck and resuspension rate for a 28 m2 room.
d Kennedy and IE-6 m (recommended) Based on a review of resuspension literature.
Strenge (1992) Recommended as a reasonably conservative default value to be applied to total surface concentration.
d This value is recommended for use in assessing IAEA (1992) 1E-6 m (recommended) reuse of tools and equipment. Used a transfer factor of 0.01 to account for the fraction of the residual surface radioactivity that is available for resuspension.
Chen (1993) 1 E-6 m d No justification given (based on use in Kennedy and Strenge 1992) l l
\ !
l 3-7 Draft NUREG-1640 l 4
- j 1
i f:
l l
Evalu tion of DirIct Reuse of Equipment S:ction 3 l
l Values for the inhalation dose conversion factors, DF inn, are taken from Federal Guidance Report -
1I (EPA 1988). Where more than one inhalation dose conversion factor is listed for a radionuclide in Federal Guidance Report 11, the largest value was selected. Inhalation dose conversion factors shown in Appendix B have been modified to include the dose contributions of progeny as described in Appendix E.
The resuspension factor, RF,, is the most poorly known parameter in the inhalation pathway analysis. Based on a literature review, information presented in previous evaluations, and the following discussion, a lognormal distribution with a geometric mean of 1E-10 cm-' (1E-08 m- )
is used for the resuspension factor for residual surface radioactivity. This value is at the low end of measured values. The low value is appropriate for this scenario, which includes the assumption that surfaces have been cleaned of easily removable, and most readily resuspendable, contamination at the time of clearance from regulatory control.
The resuspension of radioactive material from surfaces is typically modeled by the use of an equilibrium resuspension factor (in units oflength ') or a fractional resuspension rate (in units of time '). The resuspension factor is simply a ratio of the air concentration of radioactive material above a surface (pCi/cm2 ) to the concentration on the surface (pCi/cm2 ). Although the theoretical inadequacies of both the resuspension factor and the resuspension rate have been discussed in the '
literature (e.g., Healy 1971, Horst 1982), both are commonly used in modeling assessments because more technically defensible approaches are lacking. The resuspension factor and the resuspension rate can be related by Equation 3.7 RF* = 0 = fA 3.7 O Vn i Where RF, =
resuspension factor (cmd )
x =
air concentration (pCi/cm') l O =
residual surface radioactivity level (pCi/cm2 ) !
f = resuspension rate (h")
A =
area of the source of residual surface radioactivity (cm2 ) {
V =
volume of air in the room (cm')
n = rate of room air exchange (hd) j l
Measured resuspension factors and rates can vary over very wide ranges (resuspension factors l from approximately lE-11 to IE-2 m-' [ Kennedy and Strenge 1992] and resuspension rates from j approximately IE-7 to IE-2 hr' [Healy 1971]), which suggests that resuspension is a complex process of several parameters, and that the specific conditions present at the time of measurement are critical. For modeling purposes, a resuspension factor or rate is a lumped parameter that is used to account for a complex combination of mechanisms that are poorly understood, but whose net effect is observed in the real world.
A resuspensionfactor rather than a resuspension rate is used in this evaluation, although neither is better known than the other, and neither is obviously more appropriate to the reuse scenario. I The use of a resuspension rate would require additional parameters in Equation 3.4, and would, Draft NUREG 1640 3-8 l
y Section 3 Evaluation of Direct Reuse of Equipment c in turn introduce additional values and their associated uncertainties. The resuspension factor i value used in this study 1E-10 cm ' (1E -8 m ') is based on a review of relevant literature data, I combined with professional judgement and taking into account the application in this specific scenario. Unfortunately, there are no experimental data that specifically address resuspension from tools or equipment. The experimental data and recommendations summarized in Table 3.1 l
are felt to be the most appropriate available information. The range ofresuspension factors cited in Table 3.1 is 2 E-8 m ' to 4 E-3 m '. The reported data are generally from experiments that )
examined resuspension ofliquid or powder contaminated material that had been uniformly applied to clean surfaces in a laboratory-like setting. The highest values are typically associated with inefficient ventilation, excessive mechanical disturbance, or dusty conditions. Typically, the purpose of these studies was to help determine radiation protection safety guidelines for loose residual, surface radioactivity. Although this situation is not the same as assumed for the reuse scenario, it is reasonable to use the lowest value of the resuspension factors cited in the studies, rounded to the nearest order of magnitude.
Using the lowest value as a geometric mean for this assessment is appropriate because of two key assumptions inherent in the scenario definition: (1) readily removable contamination has been removed from the surface of the truck cab prior to clearance, and (2) contamination that is not readily removable is the least susceptible to resuspension. This situation represents a key difference between this scenario and the conditions for which resuspension measurements have typically been taken.
/~
The use of a mean resuspension factor near the lowest measured value is also justified based on consideration of the respirable fraction of resuspended contamination. In one of the few studies where particle size has been measured, Jones and Pond (1964) reported that measurements of air concentration were often biased by a few highly active large particles. In their study on resuspension of plutonium, they concluded that only 10W20% of the total airborne radioactivity would be respirable. Rather than include a respirable fraction parameter and attempt to define it without a sound basis, the reuse scenario analysis assumes that all resuspended contamination is respirable. Although this assumption would result in overestimating the dose from inhalation, the effect is offset by using the lowest cited value for the parameter RF,. The resulting Da value is still considered conservative.
Another complicating factor is that the residual surface radioactivity is probably not uniform.
Several studies (Dunster 1964, IAEA 1970, Healy 1971) discuss how this issue relates to resuspension values. Healy (1971) points out that in most cases, resuspension has been measured for uniformly contaminated surfaces and uniformly applied resuspension forces. Healy suggests that air concentrations are more strongly related to the total amount of surface contamination present, rather than the amount on any one limited area, and that basing allowable surface contamination limits on the highest surface levels may be too conservative.
O 3-9 Draft NUREG-1640
Evaluation of Direct Reuse of Equipment Section 3 The influence of ventilation is also a key factor that would likely result in a resuspension factor at the low end of measured values. The potential for excessive ventilation in a truck cab from open windows, air conditioning, and repeatedly opening doors would tend to reduce airbome concentrations of resuspended material via dilution and air exchange. Although increased airflow may also act to increase resuspension, this is likely a second-order effect when compared to dilution and resulting lower air concentrations (Healy 1971).
There are many other factors that contribute to the uncertainty in resuspension that are not addressed here because oflack ofinformation. These include temperature, humidity, type and roughness of surface material, degree and effectiveness of mechanical disturbance, weathering processes, and chemical state of the contamination. The effect of changes in many of these factors on resuspended air concentration is intuitive (e.g., an increase in the size of the contaminated area would likely result in an increase in the resuspended air concentration),
however, the degree and direction of the effect of other factors (e.g., specific surface conditions) is not so clear. Combining all these factors to define a " generic" resuspension factor or rate for modeling purposes is difficult. Based on a consideration of these factors and good engineering judgement, however, it is reasonable to use a lognormal distribution with geometric mean of the lowest reported resuspension factor in the model.
In an interesting review of measured resuspension factors, Brodsky (1980) concluded that the fractional amount of contamination on 1 m2 of floor or ground that would enter 1 m2 of air and be respirable by an individual over an extended period of time would be less than 104 and usually would be much lower. As a check of the methodology of this analysis against Brodsky's conclusion, an annual inhaled fraction of 2 E-6 can be derived for this reuse scenario, using parameters from Equction 3.4 and the appropriate mean parameter values. This fraction is consistent with Brodsky's estimate, which adds a degree of confidence that the model and parameter values used do not substantially underestimate or overestimate the resuspension factor.
Finally, the resuspension factor has not been consistently applied in previous evaluations. The resuspension factor in Kennedy et al. (1981) and Chen (1993) was applied to contamination that was assumed to be removable, whereas the rate in Kennedy and Strenge (1992) is intended to be applied to the total residual surface radioactivity present. The IAEA (1992) also intended for the resuspension factor to be applied to the total contamination present, however, the removability of the contamination was addressed by incorporating a transfer factor of 0.01. The resuspension factor in this evaluation of the reuse of a large piece of equipment is intended to be applied to the total contamination present at the time of clearance for reuse, because for a generic application, the full range of removable fraction must be assumed to be encountered. In addition, measurement of removable residual surface radioactivity is highly variable and uncertain (Royster and Fish 1964,IAEA 1970).
Draft NUREG-1640 3-10 O
l 1
m Section 3 Evaluition of Direct Reuse of Equipment w 3.3.3 Secondary ingestion
' Values for the ingestion dose conversion factor, DF%, are taken from Federal Guidance Report 11 (EPA 1988). ' Where more than one ingestion dose conversion factor is listed for a radionuclide in Federal Guidance Report 11, the largest value was selected. Ingestion dose conversion factors shown in Appendix B have been modified to include the dose contributions of progeny as described in Appendix E.
A lognormal distribution is used for the effective transfer rate for ingestion with a geometric 2
mean of IE-4 cm /h. This value was estimated for this scenario using the alternative methods described below. It is lower than the value used in previous reuse evaluations (1 cm2 /hr) (e.g.,
Kennedy and Strenge 1992, and IAEA 1992), however it is judged to be appropriate for this reuse scenario. !
1 The secondary ingestion model used in this study is essentially the same as that used in previous similar evaluations (Kennedy and Strenge 1992, IAEA 1992). As a review of the literature f reveals, there are no data available on secondary ingestion of radioactive material from residual - I surface radioactivity. Consequently, most relevant evaluations over the past 30 years have made )
basically the same assumption: the amount ofloose contamination on approximately l' cm 2 or j surface area would be ingested per hour (Dunster 1964, IAEA 1970, Healy 1971, Gibson and '
Wrixon 1979, Kennedy and Strenge 1992, IAEA 1992). Kennedy et al. (1981) modified the ;
% ingestion value to account for the specific scenario being addressed, and the IAEA (1992) ;
applied a transfer factor of 0.01 to the ingestion value, although there was no basis provided for 4 the value used.
Using a value of I cm 2/hr as a best estimate for the effective transfer rate for ingestion of residual surface radioactivity in this scenario has no sound, technical basis, and, as suggested by the modifications of Kennedy et al. (1981) and IAEA (1970), this value is extremely conservative.
In fact, it is envisioned that the dose from this exposure pathway in this scenario would be very ;
small, because there would be only a very small fraction of the total surface area that would j come into contact with hands (e.g., steering wheel, seat belts, various knobs and handles). Also, the value of I cm 2/hr was originally applicable to loose contamination on smooth work surfaces j (e.g., Barnes 1959, IAEA 1970), not a decontaminated, non-uniform surface such as the interior i 2
of a tmck cab. The value of I cm /hr was also originally applied to the skin as often as other surfaces (Dunster 1964, IAEA 1970), which would then require a modeling parameter to account l for transfer to the skin from the contaminated surface. Finally, using 'a value of I cm2 /hr would 1 yield results that are not credible and are counter-intuitive in this analysis. For example, the use l '
2 of I cm /hr would result in a secondary ingestion dose for this scenario that is much greater than doses from other exposure pathways for many radionuclides (i.e., > 95% of the total dose). Also, for radionuclides with energetic gamma-ray emissions, such as Co-60, an unreasonable amount of the total dose (10%-15%) would be due to secondary ingestion. The other exposure pathways have been reasonably evaluated, and it is unexpected and unreasonable that secondary ingestion j would represent such a large fraction of the total dose for so many radionuclides in this scenario.
)
J 3 11 Draft NUREG 1640 1
Evtluation of Direct R:use of Equipment Section 3 1
I Because a realistic (not overly conservative) analysis was desired for this scenario, alternative methods of estimating the secondary ingestion rate were explored. A " face validity" check can be made using the evaluation of Brodsky (1980), who reviewed residual surface radioactivity !
data and concluded that a fraction of 104is a reasonably conservative estimate of the maximum fractional amount of" plant throughput" that a single individual could intake via inhalation and that intake via ingestion would be lower. " Plant throughput" is the material in process at a facility and is judged to be analogous to the total amount of residual surface radioactivity initially present in this scenario. In order to obtain an annual fractional intake via ingestion of 104 in this scenario, an ingestion rate of 7E-5 cm2 /hr would have to be used in equation 3.5. A second alternative method of estimating the secondary ingestion rate is to base it on the intake of contamination via inhalation. These exposure pathways are linked in that they both rely on the removability of contamination from the same surfaces plus a mechanism ofintake to the body (i.e., breathing or hand-to-mouth habits). It seems reasonable that intake via secondary ingestion could be bounded by the estimated intake via inhalation because resuspension potentially comes from all exposed surfaces and secondary ingestion comes only from the fraction of exposed surfaces that is touched. Thus, a second estimate ofingestion rate is based on the inhalation pathway as follows:
IR, =
RF, BR 1E+06 3.8 where IR, - effective transfer rate for ingestion of residual surface radioactivity (cm%)
and RF u = resuspension factor for residual surface radioactivity (cmd )
BR = breathing rate for moderate physical activity (m%)
lE+06 = 3 unit conversion factor (cm /m')
Using mean values of 1E-10 cm-' for RFsc and 1.2 m3 /h for BR, an IRsc value of 1E-4 cm2 /h is calculated with Equation 3.8.
Based on the arguments and the alternative methods discussed above, a value of I cm2 /hr is clearly an unreasonably conservative value for IRsc in this scenario. Further, use of the I cm2 /hr value and the modified Intemational Atomic Energy Agency (IAEA) value (.01 cm2 /hr) in previous studies appears to have been somewhat arbitrary. Taking this into consideration, along with the other values derived with altemate methods and discussed above (1E-4,7E-5), a value 2
of IE-4 cm /hr is reasonable to use as a geometric mean in this analysis. In the absence of any empirical data, this value is thought to be reasonable for this scenario.
3.4 Reuse Scenario Evaluation Results The results of the analysis for the equipment reuse critical group scenario are listed in Table 3.2.
The mean dose factor and the 90% confidence interval for the critical group are reported for each radionuclide. These results represent dose factors for reuse of equipment cleared from NRC Draft NUREG-1640 3-12
L ')
i Section 3 Evaluation of Direct Reuse of Equipment licensed facilities, based on the bounding scenario that involves the truck driver of a cleared
- truck. The dose factors range from a high of 170 pSv/y per Bq/cm2(0.62 mrem /y per pCi/cm2) for Th-229 to a low ofless than 0.01 pSv/y per Bq/cm2(4E-05 mrem /y per pCi/cm2 ). Roughly one-third of the dose factors ar6 greater than 10 Sv/y per Bq/cm 2(0.04 mrem /y per pCi/cm 2),
roughly one-third are between 0.01-10 pSv/y per Bq/cm2 (4E-05-0.04 mrem /y per pCi/cm2), and the remaining one-third are less than: 0.01 Sv/y per Bq/cm 2(4E-05 mrem /y per pCi/cm2 ),
l The surficial dose factors from the bounding equipment reuse scenario can be compared to the l . derived surficial results of the recycle analyses, in. order to help interpret the equipment reuse l analysis results. As described in Section 4.7, the mass-based recycle dose factors were converted to a surficial basis using a surface-to-mass ratio. This yields dose factors in surficial units (i.e.,
pSv/y per Bq/cm2), j For comparison to the equipment reuse dose factors, the highest recycle analysis critical-group dose factor for each radionuclide, across the three metals analyzed in this report, was used (from Table 2.2). After comparison, it can be seen that the surficial metals recycle dose factors are l larger than the equipment reuse dose factors for all radionuclides except Mo-93, Nb-93m, and l Cd-109. This means that for almost all radionuclides, the recycle analyses surficial critical-group dose factors are more restrictive than the equipment reuse critical-group dose factors. Thus, the equipment reuse dose factors may not need to be considered when setting clearance dose criteria, I and no individual is likely to exceed the clearance criteria under conditions of any equipment n reuse scenario.
l h As described above, the radionuclides Mo-93, Nb-93m, and Cd-109 are unique in this comparison. The dose factors for Mo-93 yield the largest difference between equipment reuse and recycle, with the equipment reuse dose factor a factor of approximately 30 higher than the highest metals surficial recycle dose factor. For these three radionuclides, there is some
- possibility that a clearance dose criterion could be exceeded under the conditions described by i the equipment reuse scenario in tis analysis.
l l
l 1
i O 3 13 Draft NUREG-1640
! l i
Evaluation of Direct Reuse of Equipment Section 3 l Table 3.2 Dose factors for reuse of a large piece of equipment l Mean dose factor 90% Confidence interval pSv/y per Bq/cm 2 l Radionuclide pSv/y per Bq/cm 2 mrem /y per pCi/cm 2 5* $0* 95*
H-3 1.lE-05 4. l E-08 2.2E-06 7.5 E-06 3.lE-05 C-14 3.lE-04 1.lE-06 1.3 E-04 2.5E-04 6.4E-04 l Na-22 2.6E+01 9.6E-02 1.2 E+01 2.5 E+01 4.4 E+01 P-32 1.7E-03 6.4 E-06 7.6E-04 1.6E-03 2.9E-03 S-35 .: 1.2E-04 { , 4.5E-07 f 4.2E-05.; _
. 8.7E-05 i , 133 E-04j ,
Cl-36 1.3 E-02 4.9E-05 6.1E-03 1.2E-02 2.2E-02 K-40 1.9E+00 7.lE-03 8.7E-01 1.9E+00 3.2E+00 Ca-41 2.3E-04 8.6E-07 4.5 E-05 1.6E-04 6.6E-04 Ca-45 6.7E-04 2.5E-06 2.6E-04 5.2E-04 1.6E-03 pirJ51MM%Fyf4.71FMiMMM@ll5E%5%@dl1[.9E_423%@d$h'-62@}fdOEM2M Mn-54 7.8E+00 2.9E-02 3.6E+00 7.6E+00 1.3 E+01 Fe-55 1.5E-04 5.7E-07 2.5E-05 9.4 E-05 5.lE-04 Co-57 9.5 E-01 3.5 E-03 4.4E-01 9.4E-01 1.6E+00 Co-58 3.4E+00 1.2 E-02 1.6E+00 3.3 E+00 5.8E+00 Fe-59, 23E+00jg 18.4E-03 1.0E+00 2.2E+00 3.SE+00 -
Ni-59 1.0E-04 3.8 E-07 1.4E-05 5.6E-05 3.6E-04 Co-60 3.0E+01 1.1E-01 1.4 E+01 2.9E+01 5.0E+01 Ni-63 2.6E-04 9.8E-07 3.7E-05 1.5E-04 9.0E-04 Z n-65 4.6E+00 1.7E-02 2.1 E+00 4.5 E+00 7.8E+00 Cu-67 ' El.lE-03' ' 4.lE-06 1.7E-04 7.8E-04 3.3E-03 Se-75 2'.2E+00 ' 8.0E-03 1.0E+00 2.1 E+00 3.7E+00 Sr-85 1.7E+00 6.4E-03 8.0E-01 1.7E+00 3.0E+00 Sr-89 7.4 E-03 2.7E-05 3.5E-03 7.lE-03 1.3 E-02 Sr-93 1.4 E-01 5.0E-04 2.0E-02 6.7E-02 4.7E-01
.Y-9b . ! ' . UI 9.E-02h{ g(3,8E-05; J1 L4.9E-03f ' j9.9E-03i 9;'. j l' SE-02 {
Mo-93 3.6E-01 1.3E-03 1.7E-01 3.5E-01 6.1E-01 Nb-93m 6.IE-02 23E-04 2.9E-02 5.9E-02 1.0E-01 Nb-94 22E+0! 8.2E-02 1.0E+01 2.2E+01 3.8E+01 Nb-95 1.2E+00 4.5E-03 5.6E-01 1.2E+00 2.0E+00
_ZrySj;g,]} i 23E+00dggi8.5E-03f Vf1.lE+00;._$ .2E+001 1 2 M3.9E+00 Tc-99 1.8E-03 6.7E-06 7.2E-04 1.4 E-03 4.2E-03 Ru-103 9.6E-01 3.6E-03 4.4E-01 9.2E-01 1.6E+00 Ru-106 2.1 E+00 7.8E-03 9.8 E-01 2.0E+00 3.5 E+00 Ag-108m 2.4E+01 8.9E-02 1.1E+01 2.4E+01 4.1 E+01 M109MpQd]M[$[if}1.6E-03gg[j.9E-01by J.1E-0b f j72E-0Il Ag-11Om 2.3E+01 8.5E-02 1.1 E+01 2.2E+01 3.9E+01 Sb-124 4.9E+00 1.8E-02 2.3 E+00 4.8E+00 8.4 E+00 l125 2.6E-01 9.7E-04 1.2E-01 2.6E-01 4.5E-01 i Sb-125 5.9E+00 2.2E-02 2.7E+00 5.7E+00 9.9E+00
{-12(, ~ ' ' ' Q.2E-01[ji ' ~ [2.7E-03h y3.5E-01) - ' l 7.0E41) 7 j1.2E400
I l-131 7.4E-02 2.7E-04 2.9E-02 6.6E-02 13E-01 Ba-133 63E+00 23E-02 2.9E+00 6.2E+00 1.lE+01 Cs-134 1.9E+01 7.0E-02 8.7E+00 1.8E+01 3.2E+01 Cs-137 8.6E+00 3.2E-02 4.0E+00 8.4E+00 1.5E+01
( Draft NUREG-1640 3-14
l i
Section 3 . Evalu: tion of Direct Reuse of Equipment ;
l pg 'I able 3.2 Dose factors for reuse of a large piece of equipment l
( ) Mean dose factor 90% Confidence interval. pSv/y per Bq/cm2 j V Radionuclide Sv/y per Bq/cm 2 mrem /y per pCi/cm 2 5* 50* 95* l SI.4.In. A s.n w .lE-01u , g;i;J 3.9E-04, ,
1 ,
- 4.8E-02,c.;g ,. gl .0E-0,1,%j l .8E-Ol;,,, . )
Ce-144 4.2E-01 1.6E-03 2.0E-01 4.!E-01 7.lE-01 )
l Pm-147 3.3E-03 1.2E-05 3.7E-04 1.5E-03 1.2E-02 1 I
Eu 152 1.5E+01 5.6E-02 6.9E+00 1.5E+01 2.5E+01 Eu-154 1.6E+01 5.9E-02 7.3 E+00 1.5E+0!
{
2.7E+01 fi-155jdy ;M.5,E-OiMjjg .QS.EQQM33E-01.[@@@ERQf13h00$
Re-186 5.3E-04 2.0E-06 1.4 E-04 4.3E-04 1.3E-03 tr 192 3.2E+ 30 1.2E-02 1.5E+00 3.l E+00 5.4E+00 Pb-210 1.8E+00 6.7E-03 3.8E-01 1.lE+00 5.9E+00 !
Po *z10 4.2E-01 1.5E-03 5.6E-02 2.2E-01 1.4E+00
.Bjy10}hMMMl;6Egggf.d.M 6.0E%UdM.5E,0,5jgM2.E 04MM6,E$g -
Rn-222 5.3E-02 2.0E-04 1.4E-02 4.3 E-02 1.3E-01 Ra-223 1.2E-01 4.4E-04 5.0E-02 1.lE-01 2.lE-01 Ra-224 3.7E-02 1.4 E-04 9.7E-03 3.0E-02 9.2E-02 Ac-225 7.2E-02 2.7E-04 2.9E-02 6.7E-02 1.4E-01 k225,. .;gipe7E42fu_ h,j{ IAE44p d_pl.lE-02j %2.4E-021.,;o }l.lE-01 (
Ra-226 2.3 E+01 8.6E-0.2 1.lE+01 2.3 E+01 3.9E+01 i Ac-227 1.3 E+02 4.7E-01 1.6E+01 5.8E+01 4.5E+02 Th-227 l
1.6E-01 5.8E-04 6.lE-02 1.2E-01 3.6E-01 Th-228 4.l E+0 i 1.5 E-01 1.2E+01 2.7E+01 1.2E+02 Ol p
(f R..a.228F" ' ' i1.7E+017 Th-229 4
1.7E+02
. . ~ A'/6A.E. -02i s',
6.2E-01
- ' 7.0E+00 7 }1.4E+0l[
1.8E+01 7.5E+01 A' S5 -s3.,.6E. +< 01 i "
- 6. lE+02 l
Th-230 2.5E+01 9.lE-02 2.0E+00 1. l E+0 i 9.l E+01 l
Pa-231 8.2E+01 3.0E-01 8.2E+00 3.7E+01 3.0E+02 Th-231 1.2E-05 4.3E-08 8.7E-08 2.4E-06 5.5E-05
~
- n. ~ -232.?,..iF. M.-.W. ...O. E_+02.
. . .w.E., ? ' ^_ f.
4..1.. E. .-.0..1 x '.9..1.1.0E+01.
, m D. . W.m 9 .E4. IF. - {~ 4 0E. .+.02 .P.
j Pa-233 2.7E-01 1.0E-03 1.2E-01 2.6E-01 4.5E-01 U-233 1.3E+01 4.7E-02 1.0E+00 5.6E+00 4.7E+01 Th-234 1.8E-02 6.7E-05 8.3E-03 1.7E-02 3.0E-02 y U-234 1.2E+0 ! 4.6E-02 1.0E+00 5.5E+00 4.6E+01 )
~
J 7~^
.U-235. .. ? ' ?x>.. ' ~ . E+01. ~ ~ ~- . . f5.l.E-020.:.
. a ,7"I..2.
. - 9E400P ,7.. ~ 7.2E+00.a.-. 14.5E4011 . ~ .
Pu-238 2.7E+01 1.0E-01 2.2E+00 1.2E+01 1.0E+02 U-238 1.lE+01 4.2E-02 1.2E+00 5.2E+00 4.2E+01 Pu-239 2.9E+01 1.1E-01 2.3 E+00 1.3E+01 1.IE+02 Ps240(~ ]'y2.9E+011 J . _11.lE-Oli' ' 52.3E400f , jl3E+0l?} . ~(1.lE+02[
Pu-241 4.6E-01 1.7E-03 3.6E-02 2.0E-01 1.7E+00 Am-241 4.2E+01 1.6E-01 4.l E+00 1.9E+01 1.6E+02 I Cm-242 8.3 E-01 3.lE-03 1.0E-01 3.8E-01 3.0E+00 Pu 242 2.8E+01 1.0E-01 2.2E+00 1.2E+01 1.0E+02 l CE24FYMM23E40ii # < - K K8.5E-02T ~< N .0E+00 2 1 W ' it .0E41N: M 8.5E+01 I i
G !
! 3-15 Draft NUREG-1640 L
4 EVALUATION OF RECYCLE AND DISPOSAL OF STEEL SCRAP
/'~~N
( -
Twenty-seven exposure scenarios for cleared steel scrap that are based on current American industries are evaluatedin this section. Scenario categories include handling andprocessing, storage, transportation, product use, and disposal. Fourlandfill resident scenarios were also analyzed. A radionuclide-specific, probobilistic dose factor distnbution was calculated for the members of the exposed group in each scenario. The highest mean dose factor among the 27 scenarios on a radionuclide-by-radionuclide basis for 85 radionuclides is the critical-group dose factor f.e., for an average member of the critical group. This critical-group dose factors are reported in normalized units of pSvh per Bq/g scrap (mrem & per pCi/g) and pSy& per Bq/cm' scrap (mrem /y per pCi/cm scrap) for each radionuclide. Dose factors at the 5* , 50* , and 95* percentiles are also reported.
The mostcommon critical groups are commsrcial truck drivers canying cleared steel scrap and workers et steel refineries. Scenarios involving transport of scrap material resulted in critical group designation for almost half (39) of the 85 radionuclides in the analysis. Otherscenarios identifying critical groups for many radionuclides involve exposure while handling scrap (14 radionuclides), to refinery slag and slag leachate (12 radionuclides), and exposure to refinery baghouse dust (11 cadionuclides). Only one critical gmup involves the use of steel consumerproducts.
Critical group mean dose factors range from a high of 2.0E+03 pSv4 per Bq/g (7 mremfy porpCilg) for No-237 to n low of 4.5E-04 pSv/y per Bq/g (1.6E-06 mrem /y per pCi/g) for Ni-59. The derived surficial mean dose factors range from a high of 1.4E+3 pSv/y per Bq/cm' (5.3 mrem /y per pCi/cm') to a low of 3E-4 pSv& per Bq/cm' (IE-6 mrem & per pCi/cm'). The high cntical-group mean dose factors of Np-237 are attributed to the drinking waterexposure pathway in he refinery slag storage scenario.
Seventy-nine of the radionuclide-specifi:, critical group mean dose factors for steel are 270 pSv4 per 0 Bq/g orlower(1 mremyperpCig).
( s) s . .
This section describes the technical evaluation of the recycle of steel scrap metal that could be cleared from Nuclear Regulatory Commission (NRC) licensed facilities. The flow of cleared steel scrap was modeled using the likely sequence of steps recycled and disposed steel would be subjected to following clearance. Radioactivity concentrations in recycle byproducts and disposed materials were calculated, and potential dose factors to members of exposed population groups were estimated using reasonable formulations of potential situations where individuals could be exposed to radioactivity in cleared material and recycle byproducts.
This evaluation is based on mass radioactivity concentration (i.e., Bq/g or pCi/g) because material likely to be cleared is inventoried on a mass basis. Herefore, all calculated dose factors are initially in units of annual dose per unit mass (i.e., pSv/y per Bq/g or mrem /y per pCi/g).
This normalization allows the NRC to scale doses according to concentration of a radionuclide in scrap to be cleared. The mass dose factors have been converted to surficial dose factors by the use of a surface-to-mass ratio, which is the ratio of the surface r.rea to the mass of a piece of scrap or other cleared material. This differs from the dose factors calculated for reuse of equipment, which are based exclusively on surficial contamination as derribed in Section 3.
This surface to mass relationship and its use in cor.verting mass dose factors to surficial dose factors is discussed later in Section 4. Therefore, all dose factors are also in units of annual dose per unit surface area (i.e., pSv/y Per Bq/cm2 or mremly per pCi/cm 2),
~(A] .
y Draft NUREG-1640, Vol. I
I Recycle and Disposal of Steel Section 4 4.1 introduction to Analysis The overall evaluation of the potential dose impacts of recycling and disposal of scrap iron and steel was conducted in two general steps. First, a probabilistic material flow model specific to iron and steel scrap was developed, and distributions of material radionuclide concentrations in recycle products and disposed material were calculated. This step provided the basic radioactivity for the second step, which was the development and probabilistic evaluation of potential situations ofindividual exposure to radioactivity in cleared material and recycle byproducts. The development of the iron and steel material flow model is discussed in Sections 4.2 and 4.3, and the calculations used to implement the material flow model are presented in Section 4.4.
The dose assessment step of the overall evaluation is described in detail in Section 4.6. The exposure scenarios developed and analyzed are key parts of the assessment. The exposure e,cenarios define the exposure situation, so they play an extremely important role in the analyses.
They define the conditions surrounding the potential exposure ofindividuals and populations and, in the modeling of potential exposure, they relate the radionuclide concentration in recycled and disposed material sto the potential dose of an individual. Before developing exposure scenarios and the approach to be used to model scenarios for this study, several general objectives were defined. The desired approach was intended to:
. Simplify the evaluation of numerous possible exposure scenarios
- Identify scenarios that adequately represent critical groups a Calculate potential dose factors as realistically as possible.
The material ficw model was used to identify general scenarios that would represent a comprehensive range of potential exposure situations. Simple mathematical models of those non-specific scenarios were developed to streamline evaluation and analysis. The simplicity of the mathematical models makes them potentially applicable to a wide range of scenarios, providing flexibility for analyzing potential doses associated with whole categories of scenarios.
4.1.1 Approach to Scenario Development The majority of previous analyses of recycled material did not present a clear rationale for scenario selection and evaluation. This section of the report documents the philosophy and technical approach that were used for this project to select, evaluate, and analyze potential exposures to recycled materials.
A number of previous assessments have been conducted to quantify the potential radiation exposures to workers and the general public from recycle of contaminated materials. In general, these assessments have been based on the formulation and evaluation of fairly specific scenarios that describe hypothetical situations in which workers or members of the general public might be exposed to radioactivity in reused or recycled materials. In order to be comprehensive, this Draft NUREG-1640, Vol. I 4-2 i
)
l Section 4 Recycle and Disposal of Steel p approach requires identifying the entire range of potential scenarios and using professional judgement to select a final set for detailed analysis.
A review of the literature on radiological assessment indicates that there are two general -
approaches to scenario-based assessments. The " specific" approach attempts to medel, as accurately as possible, the actual physical circumstances surrounding a selected set of very ,
' detailed scenarios. Among the assessments addressing recycle of radioactive materials, this approach is exemplified by the work of O'Donnell et al. (1978) in which an iron frying pan was used as the reference consumer product. The analysis included calculations based on extensive details of frying pan manufacture and use.
For the purposes of the assessment proposed here, the " specific" approach suffers from several weaknesses. First, it restricts the number of scenarios that can be treated to those for which extensive, detailed descriptions can be formulated. Second, it is'open to the criticism that the chosen scenarios are too limited because they do not specifically represent other situations of interest. Third, many individual parameters are required to describe the scenario details. Each of I the parameter values in the scenario must be defended as technically sound even when only the grossest estimates are used. Finally, the data requirements of the " realistic" approach introduce serious demands on available resources. Each value must be researched, documented, and subjected to quality assurance procedures.
In contrast, a " generic" approach uses broadly defined scenarios that can be taken as j representative of a wide range of possible exposure circumstances and does not attempt to model the details of any specific, real-world situation. Several recent studies illustrate the main features of this, approach. Charles and Smith (1992), for example, modeled a wide range of consumer products using a generic geometry factor based on a cylinder of specified height, diameter, and thickness without attempting to mimic the manufacture and use of actual objects. Deckert et al.
(1992) evaluated two generic geometries, one defined as "a 1 kg object" and the other as "a 1000 kg" object to represent different categories of consumer products.
The "genuic" approach addresses each of the objections to the " specific" scenario approach.
Since each generic scenario is representative of a wide range of situations, the number of situations addressed is not so severely restricted. By representing a range of situations, carefully chosen generic scenarios can address any situation ofinterest that falls into the generic category.
Finally, the number of detailed parameters can be minimized, along with the need to estimate and defend values for each parameter.
The approach taken in this analysis is a combination of the " specific" and " generic" approaches.
Several specific scenarios have been modeled, as realistically as available data allow.' In addition, several generic scenarios have been modeled to represent a range of potential exposure situations that are similar.
4-3 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 4.1.2 Scenarics for Recycle and Disposal of Cleared Steel Scrap Metal l l
An infinite number of potential exposure scenarios for recycle and disposal of steel scrap could be postulated. The goal-based criteria set for this study required that the scenarios selected be comprehensive, appropriate, and practical. Comprehensive means that the scenarios must address all potential critical group exposure situations. The scenarios must be appropriate to actual practices in the recycle industry and conditions of product use. Finally from a modeling viewpoint, the scenarios had to be practical, in that a relatively small number of scenarios needed to include an extremely large pool of potential exposure scenarios. Selected scenarios had to account for all potential significant recycle scenarios. The very unlikely cases that could result in higher doses were excluded on the basis of not addressing the design objective of the analysis.
The approach for this evaluation is similar to that taken by Charles and Smith (1992), who ,
evaluated the feasibility of different options for managing large volumes of very low level waste. j The management options included scenarios similar to those selected for this report, including clearance followed by recycling and disposal of steel and concrete in landfills. The exposure scenarios used in their models were derived from adopting the various management options. The methodology used generic exposure scenarios that are similar to the scenarios used'in this evaluation in temis of their genetic nature. Scenarios used in previous studies, including scenarios reported by Charles and Smith (1992), are shown in Table 4.1. 1 Table 4.1 Scenarios discussed in previous studies 1
Work-related Non-worker
. Decontamination and dismantling of concrete and . End product use (i.e. frying pan, steel furniture, steel structures and handling scrap during the steel car, steel reinforcement in houses, large process and small products)
. Transport of scrap to smelter or disposal facility . Smelting process (airborn: effluents)
. Exposure to scrap piles before smelting . Slag in roadbeds, foundations of houses, reuse
. Repair of contaminated machinery of contaminated slag in concrete
. Operation of smelter and subsequent processing . Landfill and sanitary disposal of waste products
. Building renovation or demolition or contaminated scrap (leachate, inadvertent
. Landfill dispose.1 (operation of facility or waste intrusion) fires) . Incineration of contaminated scrap
. Reuse oflarge concrete masses (building . Building occupancy by the public renovation) . Drinking water-drinking water that contains
. Reuse of contaminated slag in concrete radionuclides leached from surface soils manufacture production / manufacture of end .
Residential (contaminated soil) products . Shallow repository disposal
. Reuse of large concrete masses (building occupancy)
Rather than attempting to initially define a specific " bounding" scenario, in which potential exposure is maximized even though the combination of circumstances is very improbable, broad scenario categories and a combination of general and specific scenarios within the categories were identified and evaluated. Scenarios were then evaluated so that dose factors calculated in the model would be realistic estimates for potential real-life situations.
Draft NUREG-1640, Vol.1 4-4
Section 4 Recycle and Disposal of Steel The material flow model provides a basis for developing exposure scenarios. Junctures in the
! material flow that provide opportunities for exposure to radionuclides in recycled iron or steel defme the broad scenario categories, such as handling or product use. Scenarios within those categories describe the conditions surrounding the potential exposure ofindividuals and populations. For example, seveml scenarios within the handling category evaluate potential exposure of workers to a variety of material (e.g., scrap metal, baghouse dust, refined metal product) and locations (scrap yard, i
refinery, baghouse). The exposure scenarios were selected to comprise a reasonable set of potential 1 exposures to the estimated concentrations of radioactivity in scrap metal or refmery co-products.
The combination of a " specific" and " generic" approach used to develop exposure scenarios provided i flexibility in defming a set of reasonable scenarios for identifying critical groups. This approach addresses a wide range of potential exposure situations and also lends itself to future evaluation of additional scenarios ofinterest.
4.2 Flow of Recycled and Disposed Steel Scrap 4.2.1 Conceptual Description This section presents the conceptual model that describes the flow of cleared steel scrap through the
- normal refining process, beginidng with the generation of scrap, through refiming, manufacturing, product use, and finally disposal. Figure 4.1 presents a schematic diagram of the overall matedal flow G conceptual model for steel scrap. Both the mass and radioactivity of steel scrap follow this flow model. As seen in Figure 4.1, there are several distinct steps in the refining process. Each of these is discussed in the following subsections. Direct reuse of equipment is discussed in Section 3.
'4.2.2 Sources of Material There are two sources of materials for the steel refining process: the primary and secondary metals pools. The primary metals pool consists of pig imn smelted from ore. The material from this pool would not be contaminated at any point by the recycling of scrap cleared by NRC licensed facilities because scrap is not used during the smelting of ore. Approximately 5.2E+7 t (5.7E+7 tons) of pig iron was consumed in 1995 in the U.S. (Fenton 1996).
The secondary metals pool is comprised of scrap metal. A total of 7.2E+7 t (7.9E+7 tons) ofiron and steel scrap was consumed in the U.S. in 1995 (Fenton 1996). There are three types of scrap metal used in the steel-making industry: home, new, and old. Home scrap consists of unusable metal produced during the processing or fabrication of steel into a fonn usable for manufacturing. Home scrap is usually high-grade metal with very few impurities. Even though home scrap is produced at the refinery, it is still considered a secondary metal because it is not the processed raw material, pig iron.' New scrap is produced during manufacture of end products. New scrap is also high-grade metal with very few impurities. Oldscrap includes obsolete, wom- out or broken products that have been
(
4-5 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 att dust 33~
Secondary "- C Manufacturing Metals 4 Steel Refinery slag C Transportation r &
Pool nietal product C Processing N 1 f Transportation Scrap Dealer a Recycle Distribution Pr 1I
)k Transpeit-tien HandNng Use d
Existing Recyclers j
/ / Direct Disposal Disposal r
Figure 4.1 Flow of steel scrap used by the general public or industry. Old scrap is usually low-grade metal, and the chemical composition is not well-known. Therefore, it must first be sorted, sized, and classified. Cleared scrap metal from the nuclear industry would be considered old scrap.
The modeling for this analysis does not distinguish between the different types of scrap. Cleared materials are assumed to be mixed with a single source of uncontaminated scrap-roughly the total of old, new, and home scrap sources.
' lie two sources of secondary metals considered in this evaluation are conventional recyclers, and potential, cleared scrap metal. Recyclers are the current producers of scrap metal and consist of the general public (e.g., recycling steel cans), industry (e.g., recycle automobiles), or mufacturers (e g., scrap produced during manufacture of end products).
l ' ne main source of the cleaed scrap for this study is the nuclear industry (deconunissioned l material from nuclear facilities), which consists mainly of commercial power plants, test and research reactors, and industrial nuclear facilities. Other producers of such scrap include the Department of Energy (DOE) weapons complex and the Department of Defense (DOD), which could contribute slightly contaminated scrap primarily from conventional weapons testing and army and navy test reactors. Approximately 3.0E+3 t/y (3.3E+3 ton /y) of potentially cleared I
Draft NUREG-1640, Vol. I 4-6
Section 4 Recycle and Disposal of Steel q material is generated each year from NRC licensed facilities; increased dismantling and decommissioning activities by. DOE could increase the mass of steel to about 7.1E+4 t/y (7.8b+4 ton /y) (NUREG/CR-5610') for a limited number of years.
Following entry of cleared material into the steel pool, a continuing buildup of residual radioactivity levels in steel products to significant levels is not likely. Especially unlikely is any significant increase in potential individual doses (compared to collective doses). This is because
- 1) ongoing radioactive decay occurs; 2) virgin, raw materials are continually added to the metals production processes, and 3) cleared material will comprise only a small fraction of the total recycled amount of any material. Therefore, the radioactivity concentrations in any subsequent recycling will likely be lower than that resulting from the initial recycle. Therefore, any .
individual doses from secondary recycle would likely be lower than those calculated for initial recycle in this analysis. The potential, long-term buildup of radioactivity in the steel pool may be a collective dose issue, but it is not considered an individual dose issue, and is therefore outside the scope of this analysis.
4.2.3 Transportation and Processing of Scrap Scrap cleared by a NRC licensed facility must be commercially transported to a scrap dealer or processor. Not all cleared scrap is likely to be suitable for recycle, so some would be transported directly to a disposal site. In all cases, transportation could occur either by truck or rail.
C
\, After scrap is processed at a scrap dealer, it is transported by rail or truck to a refinery, where it is usually off-loaded directly for melting in a furnace. Two types of processes are involved in steel mAing: smelting and refining. Smelting treats the raw material (ore), to separate the metal peation (pig iron), from the waste slag. Because the smelting process does not accept scrap, it is not discussed further in this report.
Scrap cleared from NRC licensed facilities would become part of the generic refining process represented by Figure 4.2. Refining takes pig iron produced at a smelter and refines it to a specified impurity level by adding differing types and amounts of scrap metal. Refining is also commonly done by using only scrap with no pig iron. The two types of steel refineries currently in use (integrated and non-integrated) differ primarily in characteristics of the charge (i.e., the mateial that is melted in the furnace per cycle). The integrated process accepts small amounts of scrap per charge and, therefore, produces a product of higher purity. The non. integrated process, on the other hand, can use up to 100% scrap metal in a charge. This results in a product with lower purity but with greater strength.
' Recycle / Reuse Literature Search Report, SAIC,1994, scheduled to be pubikhed as NUREG/CR-5610.
4-7 Draft NUREG 1640, Vol.1
Recycle and Disposal of Steel Section 4 I1 1 Mined Ore Fu a e Scrap Pile Flux.
Pig Iron F
< t L f r
Metal Product Distribution Fur ac (a tYrN0ve) Furn ce(alS~e ative)
Emissions
Slag Pile Slag Pile Exhaust Gases
. Manufacturm8 and Dust 7 v D
\evice/
m n Dust Distri tion
.r l
Stack Figure 4.2 Generic refining process Draft NUREG-1640, Vol.1 48 O
l
V.
Section 4 Recycle and Disposal of Steel
, Together, integrated and non-integrated mills consumed a total of approximately 6.2E+7 t
( (6.8E+7 ton) of steel scrap, and produced a total of 9.52E+7 t (1.0E+08 ton) of raw steel in 1995 (Fenton 1996). A small amount of scrap and pig iron is consumed by foundries and other types of refineries [9.78E+6 t (1.1E+7 tons)) of scrap. However, because these facilities contribute
- only a small percentage (<1%) of the total steel production, they are not included in this analysis (Brown 1993). Refinery worker activities at the two types of steel refineries are similar, and on average, it takes 3.5 man-hours to produce 0.907 t (1 ton) of steel (NUREG/CR-5610').
4.2.3.1. Integrated Steel Mills The integrated steel mills use 'mainly basic oxygen furnaces (BOF). The input material for this type of furnace consists of molten pig iron, scrap, and flux materials (mostly lime and silica or limestone). (Flux materials are added to achieve a desired composition.) The exothermic reaction of oxygen (added during the process), with the molten pig iron, oxidizes and removes impurities in the iron while providing heat for melting the scrap. The amount of oxygen added varies depending on the quality of the scrap and the desired final steel chemistry. Furnace capacities of BOFs range up to 300 t (330 ton) per charge, and the required time per melting cycle typically ranges from 25 to 45 minutes (EPA 1986). The average size of a charge in a BOF refinery is estimated to be 58 t (64 ton) with an average of 5580 charges per year for one refinery.
The fumes that are generated when oxygen is added to a BOF are captured by the primary exhaust hood and cleaned by high pressure venturi scrubbers or electrostatic precipitators. The fumes generated during melting, tapping (pouring molten steel), and slagging (decanting slag)
'4 are captured by local or canopy hoods and transported via a duct system to a baghouse. (For this
\ report the fume collection system is generalized and referred to as a baghouse.) The BOF baghouse is assumed to be 99.9% efficient because of the cleaning efficiency of the primary collection system in conjunction with the baghouse (Mody and Jaknet 1988).
Scrap used in t'ie BOF refining process is largely home scrap. Because of the small percent of old scrap used, the concentrations of Environmental Protection Agency (EPA)-listed hazardous metals (i.e., lead, cadmium, and chromium) in the dust are below regulatory limits. Therefore, BOF dust is not listed as a hazardous waste (EPRI 1993).
The integrated mills produce " flat" products (e.g., sheets and strips) and supply the consumer goods market, mainly automotive and appliance. In 1995, BOFs consumed about 22% and %%
of the total scrap and pig iron, respectively used in the U.S., while producing approximately 60%
of the total raw steel for that year (Fenton 1996).
4.2.3.2 Non-Integrated Steel Mills The non-integrated steel mills employ mostly electric are furnaces (EAF), and primarily produce carbon steel. The input material to an EAF is usually 100% scrap, with a very small amount of
' Recycle / Reuse Literature Search Report. SAIC.1994, scheduled to be published as NUREG/CR-5610.
4-9 Draft NUREG-1640, Vol. I
i i
Recycle and Disposal of Steel Section 4 flux. Capacities of EAFs vary, ranging from a diameter of 2 m (6.6 ft) and a product capacity of 3 t (3.3 tons), to 12 m (39 ft) with a capacity of 360 t (397 tons)(EPA 1986). Melting cycles range from about 1 % to 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> to produce carbon steel. Based on information presented in the 1993 Directory ofIron and Steel Plants (AISE 1993), the average size of a charge in an EAF refinery is 88 t (97 ton) with an average of 5,580 charges per year for one refinery.
The fumes generated during the meltdown and refining period of an EAF are evacuated directly off the fumace (direct shell evacuation) and transported via a duct system to the collection system. The fumes produced during melting, tapping, and slagging are evacuated through a fume collection hood on the roof of the building, then transported through a duct to the collection system. The most efficient, cost-effective, and typical collection system used to control the EAF fume dust is the fabric filter baghouse system. Discussions with industry indicate that these systems typically have a collection efficiency greater than 99% when running optimally.
However, Cass and Langley (1977) provide data from a controlled experiment that measured dust characteristics from an EAF refining carbon steel. Measurements included particle size and mass at both the inlet and outlet of a baghouse. Ten separate experiments were run. The mass fraction penetrating the filters was reported to have a mean of 1.904 % with a standard deviation of 0.3862 % (Cass and Langley 1977). The mean value corresponds to a filter efficiency of 98.1
%. The mass penetration value that is two standard deviations above the mean is 2.68 %,
corresponding to a filter efficiency of 97.3 %. The mass penetration value two standard deviations below the mean is 1.13 %, corresponding to a filter efficiency of 98.9 %.
Cuscino (1979) reports the results of emission measurements at a variety of steel refineries. The data are difficult to interpret because of variations between facilities and variations between sampling procedures. Two pairs of values are given which provide measures of dust entering and leaving a baghouse. These measurements provide two direct estimates of filter efficiencies at 97.3% and 95.0%. In addition, four values related to dust production are reported for emissions measured downstream from a baghouse at an EAF refinery making carbon steel from scrap. These are 0.02 kg dust per metric ton of steel produced and 0.072,0.16, and 0.85 kg/t of scrap input. If one assumes 15 kg of dust enters the baghouse per metric ton of steel produced and 90 t of steel is produced per 100 t of scrap (see Section 4.3), these values correspond to mass penetration fractions of 0.15%,0.54%,1.2%, and 6.3% with a mean of 2.0%. The corresponding filter efficiencies range from 99.8% to 93.7% and average 98%. Although these values are questionable because of the quality of the original data and the assumptions lequired to interpret them, they are consistent with values from controlled experiments. They are used here to justify a wider range of uncertainty in real baghouse efficiencies than in the controlled experiments.
Cuscino (1979) reports that, depending on refinery configuration, significant fractions of refinery dust may not be ducted to the baghouse and may be emitted unfiltered to the atmosphere.
Therefore, a value of 98% is a reasonable most likely value for the baghouse filter efficiency, BHer, for an EAF refinery.
Because a large percentage of an EAF charge is comprised of old scrap, the concentrations of hazardous metals (i.e., lead, cadmium, and chromium) in the baghouse dust, which are regulated under the Resource Conservation and Recovery Act (RCRA), are above regulatory limits Draft NUREG-1640, Vol.1 4-10 O
E Section 4 Recycle and Disposal of Steel l
l p . (EPRI 1993).' Therefore, the EAF baghouse dust is listed by the EPA as a hazardous waste and is b) t - handled differently than BOF dust.
The non-integrated mills produce high-strength, low alloy steel, supplying mainly the construction industry. In 1995, EAFs consumed about 64% and 3% of the total scrap and pig
' iron used in the U.S., while producing about 40% of the total raw steel made in that year
- (Fenton 1996). The remaining 14% scrap and 1% pig iron were consumed by other facilities
- (e.g., blast furnace, cupola furnace, etc). It is common practice for an EAF to operate using only scrap metal as feed.
The amount of oxygen used in the EAF process is assumed to be about the same as the amount used for the BOF process. For the purpose of this analysis, a BOF and an EAF are treated the same for determining the elemental partitioning factors, but are modeled differently for other factors, including scrap dilutions, baghouse efficiency, end products, and EPA regulation of the dust. Table 4.2 lists the differences that are relevant to the modeling in this analysis.
Table 4.2 Key assumptions for the steel material flow model Assumptions Basic oxygen furnace Electric are furnace End product and use flat products and used mainly in the high-strength, low alloy steel and consumer goods market used mainly in the constmetion industry
[ End use of baghouse dust disposed ofin a sanitary landfill on site sent to metals recovery, fertilizer, or
\ disposalin a hazardous (RCRA) landfill Temperature inside furnace 1600*C 1600*C Temperature inside the baghouse 190*C 190*C Chemical form of elements entering oxides oxides baghouse Efficiency of baghouse 99.9 % 98 %
- Type of slagging agent used in basic basic furnace Average size of a charge 58t 88 t Average number of charges per year 5,580 5586 for a single refinery l
O
~f 4-11 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 4.2.3.3 Output of Refinery Processes During the refining process (using either the EAF or BOF), the fumace contents separate into four different end products: off-gas, dust, slag, and metal (Figure 4.2). Both the mass and radioactivity are redistributed (partitioned) into the different end products. To account for this in the material flow modeling, partitioning factors for both mass and radioactivity were developed and are discussed in detail in Section 4.3.
Each of the end products undergoes a different process, use, and final disposal. The off-gas includes elements that are completely volatilized into stable gases or very fine particles during refining and exit the refinery stack. Fumace fume dust includes elements that are volatilized from the furnace, form particulates when cooled, and are collected in baghouse filters. Neither EAF or BOF air pollution control systems are 100% efficient, and a small percentage of the dust exiting the baghouse is released to the atmosphere with the off-gas. After collection, BOF dust is placed in a sanitary landfill.
The baghouse dust from EAF facihties is classified as a RCRA hazardous waste because of the metal content (EPA Waste No. K061), and refineries have two options for disposition of the dust:
treatment and disposal, or delisting. Both of these options are addressed in the material flow modeling. At the time this issue was investigated, the two most common treatment and disposal methods in use were 1) immobilization treatment, followed by disposal, and 2) high-temperature metals recovery. Immobilization and disposal is explicitly addressed in the modeling for this analysis, as described in subsequent sections of this report. Metals recovery was also investigated, including calculation of radionuclide concentrations in recovered metal products.
However, the calculated radioactivity concentrations have a very large degree of uncertainty ,
associated with them (due primarily to the lack of specific information about the proprietary metals recovery processes) and were judged to be inadequate to support development of new scenarios associated with metals recovery. Therefore, the radionuclide concentrations of recovered metal are not used further in this analysis, but their uncertainty suggests areas for l future investigation, and also to address the types of questions that can arise during rulemaking )
and related activities. Electric are fumace dust is transported by truck to either a hazardous landfill facility or to a processor. At either type facility, it is typically unloaded in an enclosed building, where it is immediately placed in a bin and moistened with water for dust control.
Steel-making slag is not considered a hazardous waste, therefore, it can be reprocessed for use or ;
directly disposed of. Typical uses of slag are railroad bases, aggregate, and railroad ballast.
After slag is removed from the furnace and cooled, it is stored in piles outdoors at the refinery until it is either used by the refinery or transported to a slag processor. Approximately 10% of the total slag produced in 1992 was used at the plant where it was originally produced (Solomon 1993). Slag is transported from the refinery to manufacturers or processors by either truck, rail, or waterway. Of the slag produced and transported in 1992,82.9% traveled by truck with an average range of 45 km (72 mi),3.6% traveled by waterway with an average range of 400 km (250 mi), and 3.5% traveled by rail with an average range of 400 km (250 mi)
(Solomon 1993). As those figures indicate, most slag is used within a 50 km (80 mi) radius ofits source.
i
! Draft NUREG 1640, Vol.1 4-12 O '
l
c .
Section 4 Recycle and Disposal of Steel Basic oxygen furnaces and EAFs yield different types of metal products. Electric arc furnaces pi manufacture mainly bar products for use in the construction industry. Thes products have a lower purity and a greater strength than BOF products and do not require additional l
manufacturing or processing prior to use. The metal produced at mills using BOFs is usually in i
sheet form and will undergo additional manufacturing or processing for use in items such as appliances or automobiles. Both product types follow the flow model presented in Figure 4.1.
Basic oxygen furnace metal products are transported from the mill to manufacturers or ,
processors by either truck, rail, or waterway.
]
Manufacturing and processing converts slag and BOF metal products created at the refineries into finished products. Manufacturing involves activities such as cutting and shaping the metal.
Electric arc furnace refined metal products are not processed after leaving the refmery.
After a metal product or slag is manufactured into a finished product, it must be transported and distributed to the general public (i.e., end user). Facilities involved in the distribution of finished metal products, produced at both EAFs and BOFs, include stores, warehouses, and car lots. Slag is usually distributed and transported directly from the refinery where it is produced or from the manufacturer where it is processed. EAF dust is usually processed (immobilized) at the same facility where it is disposed of and requires no additional transportation. EAF dust that is processed into fertilizer is containerized and shipped by truck to distributors.
There are other refinery byproducts in addition to refined metal, slag, and baghouse dust.
However, these represent comparatively small material flow pathways, and have not been l [U evaluated in this analysis. One such bypro' duct is mill scale, which is the oxidized surface of !
j refined steel that is produced, for example, during the hot rolling of steel slabs. Scale consists of l a mixture ofiron oxides, and therefore has a high iron content (e.g.,55%). Scale production can be as high as 1% of refined steel output at a refinery, but is more typically between 0.5% and 0.75%. Scale must be removed from refined steel because it results in unwanted characteristics of the finished steel. Because ofits high iron content and other characteristics, mill scale is a commodity and can be used in the steel industry as well as the cement industry. Partitioning of !
radionuclides to scale has not been evaluated for this analysis, but it would be dependent on the partitioning to refined steel, and it is likely that radionuclide concentrations in scale would be roughly the same as in refined steel. Radionuclides in any mill scale that is returned to the steel
- industry would likely end up in refimed steel at some point, at lower concentrations than initially l in the scale. The fate of radionuclides in scale that is used in the cement industry is unknown, however the evaluation of slag use in concrete in this analysis may be an adequate substitute analysis for this potential flow pathway.
l.
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v 4 13 Draft NUREG-1640, Vol.1 g
Recycle and Disposal of Steel Section 4 4.2.4 Di.sposition of EAF Baghouse Dust Between 450,000 and 590,000 t (500,000 and 650,000 tons) of EAF baghouse dust is generated each year in the U.S. This dust is classified as a RCRA hazardous waste because of the metal content (EPA Waste No. K061). For many years, the majority of the dust was thermally treated for metals extraction or disposal. Data available at the time this was formally investigated (for calendar year 1992) indicated processes that an estimated 86.5% of the EAF dust generated was treated by high-temperature metals recovery (EPRI 1993). Therefore, the high. temperature metals recovery process was evaluated for this analysis. However, because of a high degree of uncertainty in the modeled radionuclide concentrations of byproducts, plus evolving industry practices, these concentrations were not used for scenario evaluation.
Also in 1992, approximately 11.2% of all EAF dust collected by baghouse filters was treated and disposed of as hazardous waste (EPRI 1993). The standard treatment prior to disposal is immobilization. Electric are furnace dust is immobilized by mixing it with hydraulic cement, the most common of which is Portland cement. Cement hydration reactions require that the waste-cement mixture have an alkaline pH. While cement-a highly alkaline medium-is quite effective itselfin raising the pH of most wastes, its effectiveness is limited, particularly with highly acidic wastes. Such wastes are typically pretreated to raise the pH before solidification.
At the disposal facility, EAF dust is treated to obtain a waste form that meets RCRA immobilization requirements. Typically about 100 g of EAF dust is mixed with about 30 g of two additives (liquid reagent and dry cement), which results in a dilution factor of 0.77; the density of the solidified product is typically 1.36 g/cm 3(Logan 1993). It is then loaded into steel roll-off boxes or drums, which are temporarily stored in the yard. When laboratory tests confirm that the waste meets EPA treatment standards, the containers are placed in the disposal trench.
The remaining 2.3% of EAF dust collected by baghouse filters was used for the manufacture of fertilizer in 1992 (EPRI 1993). According to 40CFR266.20, which details use of EAF dust in fertilizer, EAF dust used in fertilizer is no longer regulated under RCRA; however, this classification is subject to change. In this application, fertilizer manufacturers treat the dust with sulfuric acid to form soluble zine compounds and insoluble lead sulfates. Fertilizer manufacturers require high zine content (preferably above 20%) in the dust (EPRI 1993) to achieve a reasonable maximum concentration of zine in fertilizer of 3%. Assuming that the initial concentration of zine is 20% in the EAF dust and that the final zinc concentration is 3% in enriched fertilizer,1.36E+5 g of EAF dust would be added to 7.71E+5 g of non-enriched fertilizer (additives).' This results in a dilution factor of 0.15. All EAF dust shipped for use in fertilizer manufacturing is consumed during the process. The enriched fertilizer is loaded into packing loaders, boxed, and shipped out on tmcks.
I f
The disposition of EAF dust has been an issue for the steel industry for several years; as a result l of this, the regulatory situation is evolving. Because of the regulatory and liability issues, I l l
' Personal communication between Mary Anderson (SAIC) and L Wyett (Frit Fertilizer). February 1995.
Draft NUREG-1640, Vol.1 4-14 l
Section 4 Recycle and Disposal of Steel industry has responded rapidly with new practices for the disposition of EAF dust: these
.(
changing practices, however, make the process difficult to analyze. New recycle processes are being developed to remove heavy metals and zinc oxide, producing various byproducts such as building bricks, roofing granules, and abrasives. Also, several approaches to minimize the amount of dust requiring disposition are being investigated by the steel industry. This includes efforts to minimize the generation of dust and various on-site recycling programs. There is sufficient economic motivation and environmental liability to pursue such efforts, so practices for the disposition of EAF dust will likely continue to evolve.
4.2.5 Product Use Slag or finished metal products are used by the public for many applications. Examples of finished metal products from BOFs are small appliances (e.g., toasters), automobiles, public transportation vehicles, furniture, and small objects that would be in contact with the body, such as jewelry. Types of finished EAF metal products include large items (reinforcements for houses, rebar, fence posts) and smaller objects (tools and belt buckles). Slag can be used in commercial applications for construction (various types of concrete aggregates and products),
road-building (road bases), glass manufacture, mineral wool, railroad ballast, and soil conditioning (Solomon 1993). Fertilizer containing EAF dust is used by the agricultural industry to fertilize produce that is meant for human consumption. However, because of the concerns discussed above, EAF dust fertilizer is not included in this analysis.
4.2.6 Disposal V The ultimate endpoint for finished metal products, slag, and BOF dust is disposal in a public sanitary landfill (RCRA Subtitle D). The types of objects that could end up in a public sanitary landfill include discarded end products, waste from manufacturing, slag directly from the refinery, products made from slag, scrap not suitable for reuse or recycle, and BOF dust. The ultimate endpoint for immobilized EAF dust is a hazardous landfill (RCRA Subtitle C).
4.3 Mass and Elemental Partitioning Factors for Refinery Operations Redistribution (partitioning) of the radioactivity and mass present in cleared steel scrap entering the refinery furnace must be followed to estimate concentrations of radionuclides in various recycle end products. Partitioning factors are defined as the fraction of original radioactivity or mass of scrap entering the refinery furnace that would be present in various end products.
For this analysis, the mass of scrap metal entering a furnace during the refining process is redistributed into the three inunediate products of the refining process: metal product, slag, and dust. Radioactivity in incoming scrap metal is also redistributed among those products, as well as in the off-gas leaving the refinery stack. Assumptions and data used to develop the partitioning factors, as well as calculated partitioning factors used in the material flow modeling for both mass and radioactivity, are discussed in the following sections.
/%
4-15 Draft NUREG-1640, Vol.1
Recycle and Disposal of Steel Section 4 4.3.1 Mass Partitioning Factors Mass partitioning factors are calculated an.1 used for the metal product, slag, and dust.
Partitioning factors for the metal product and dust are based on literature, while those for slag are calculated by approximating conservation of mass.
The partition factor distributions are not sampled to ensure that they add up to 1.0 for any single run within a Monte Carlo simulation. This is not necessary since each exposure scenario calculates dose factors from radioactivity in only one material at a time (i.e., refined metal, slag, or baghouse dust).
4.3.1.1 Metal Product Industry data indicates that EAFs typically produce 90 t (99 tons) of steel for every 100 t (110 tons) of scrap used (Lankford et al.1985). Data reported by the American Iron and Steel Institute for the period 1988 through 1992 yield an average mass partitioning factor for metal product (fpi) of 90% with a range from 85% to 95% (AISI 1993). These estimates are supported by three industry contacts (Border Steel, TX , Bayou Steel, LA, and Arkansas Steel, AR). Each of these three refineries indicated that they controlled their process toward a target yield of 90% '
with a range from 88% to 92%.
4.3.1.2 Baghouse Dust All available references give dust generation rates in terms of mass of dustper mass ofsteel produced not per mass of scrap used. In order to estimate a mass partitioning factor, some assumptions must be made regarding the mass of steel produced per mass of scrap used. The equation for the mass partitioning factor for dust, foi, is as follows:
foi = Massa,, / Mass,c,,,,,,a
= (Mass .,a / Mass,u p,a,ca) * (Mass,,,,i p,,a,c,a / Mass,c,,,,,,a)
= (Massaus, / Mass,,,,i p,ama)
- fpi The value used here for pi f (mass partitioning factor for metal product) is 90 t (99 tons) of carbon steel produced per 100 t (110 tons)of scrap used (see Section 4.3.1.1). ,
l There is remarkable consensus in the literature for a best estimate value of 15 kg of dust per I metric ton of carbon steel produced at EAF facilities. Brough and Carter (1972) and Venturini (1970) give 15 kg/t a " measured operating value." This value is supported by two industry contacts (Border Steel, TX and Arkansas Steel, AR). EPRI (1993) presents 15 kg/t of capacity as an industry average of 52 plants responding to their survey. A dust production rate of 15 kg/t of steel produced corresponds to an foi of 0.014.
l Estimates of the range of dust production are also fairly consistent. Brough and Carter (1972) l cites a range of 7.5 to 20 kg/t as a specification for baghouse design. Elert and Wiborgh (1992) cites a range of 10 to 15 kg/t for Swedish EAF steel mills. Szabo and Gerstle (1978) gives a Draft NUREG 1640, Vol.1 4-16 O l l
l
I
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Section 4 Recycle and Disposal of Steel n range of 12 to 29 kg/t. The range used for this evaluation is from 10 to 25 kg/t which
( corresponds to a range in fa of 0.009 to 0.023.
4.3.1.3 Slag Steel yield is well-known because it is of significant economic importance, and baghouse dust production is well-known because it is a regulated material. However, the mass of slag produced per mass of scrap is not well-documented in the literature and has not been readily available from industry contacts. Estimates for slag production can be calculated based on a mass balance for a l typical carbon steel recipe. In addition to scrap, the typical EAF uses fluxing agents (mostly l lime and silica or limestone) at a rate of about 38 kg/t of scrap (AISI 1993). Small amounts of l other materials are included in the melt (carbon, consumed electrodes, and refractory brick). In l addition, oxygen is consumed in the oxidation of materials that are incorporated into slag. Slag i consists primarily ofiron oxide, calcium, and silicon oxides from oxidation of fluxes, along with I
oxides of various metals appearing as impurities in scrap. Slag is about 20% oxygen by weight (Lankford 1985).
l l Table 4.3 provides estimates for slag production using a mass balance approach. Sufficient ,
l l oxygen has been included to account for oxidation of the fluxing material and the difference in l mass between the scrap and the steel produced. The masses of steel und dust produced are taken l from preceding sections of this report. Dust production is assumed to be inversely proportional to steel production. That is, the maximum dust production of 2.0% occurs when steel production is 85%, the minimum dust production of 0.9% occurs when steel production is 95%, and the O average dust production of 1.4% occurs when steel production is 90%. Using this method, a V value of 0.16 is chosen for the most likely estimate for the mass partitioning factor for slag, fa.
Table 4.3 Values used for calculation of EAF mass partitioning factors (metric tons per charge)
Nominal High' Low' l Furnace input Scrap 100 100 100 Flux 4 4 4 Oxygen 3.15 2 4.3 Total 107.15 106 108.3 Furnace Output Steel 90 95 85 Baghouse Dust 1.4 0.9 2.0 Slag 15.75 10.1 21.3 Total 107.15 106 108.3
- High = Highest yield of steel (lowest production of baghouse dust and slag) l Low = Lowest yield of steel (highest production of baghouse dust and slag)
O U 4-17 Draft NUREG-1640, Vol.1 I
i Recycle and Disposal of Steel Section 4 4.3.1.4 Basic Oxygen Furnace As cleared steel scrap is processed in a refmery. new refined metal, dust, slag, and off-gas is produced. A mass partition factor is used in the model to simulate the quantity of each of the four media produced duririg refining. The uncertainty in the mass partition factors is related to a number of factors including composition of the scrap, the refming method used, fluxing, charging, and other factors. The mass partition factors are different for EAF and BOF refinery processes because of different furnace charging procedures.
The efficiency for an EAF has a most likely value of 90% with a range of 85% to 95%.
According to Lankford (1985) a typical basic oxygen furnace (BOF) has a yield of about 88%.
(i.e.,88 t of metal product produced for every 100 t charge). However, a charge in a BOF can consist of 20-35% scrap with a typical value of about 32.2% (Lankford 1985). A value of 32 t of scrap for every 100 t of metal charge is used for the amount of scrap in each charge.
Because no information was fotmd to indicate that a typical BOF is less efficient than an EAF, the same efficiency range for the BOF metal-product mass partitioning factor is used.
The only available reference gives dust generation rates in terms of mass of dust per mass of i steelproduced not per mass of scrap used. According to EPA (1986), about 14 kg of dust is pro-duced for every metric ton of metal product produced in a BOF. In order to estimate a mass l partitioning factor for dust, some assumptions must be made regarding the mass of steel j produced per mass of scrap used. The equation for foi is as follows: l dI = Mau,, / M,c,,, ,,,4
= (Maos, / M,,,,i p,,4,,;;,4) * (M,,,,i ,,oa,c,a / M,c,,,,,,a)
= (Maos, /M,,,,i p,oo c,4)
- f,i The mass of slag produced per mass of scrap is not well documented in the literature and has not been readily available from industry contacts. Steel yield is well known because it is of economic importance. Estimates for slag production can be calculated based on a mass balance for a typical carbon steel recipe. In addition to scrap and pig iron, the typical BOF takes fluxing agents (mostly burnt lime and dolomitic lime) at a rate of about 90 kg/t (180 lb/ ton) of metal product produced (Lankford 1985). Small amounts of other materials are included in the melt (carbon, consumed electrodes, refractory brick, and fluorspar). In addition, oxygen is consumed in the oxidation of materials that are incorporated into the slag. Oxygen is added at a rate of about 2 m2 per minute per metric ton for a period of 16 to 25 minutes (Lankford 1985).
Assuming an average period (20.5) for the oxygen blow and density of 1.43 g/L for oxygen at standard temperature and pressure (CRC 1992), approximately 5.9 t of oxygen is used for a 100 t (scrap + pig iron) charge.
Table 4.4 provides input and yield estimates used for calculating mass partitioning factors for the metal product, dust, and slag.
Draft NUREG-1640, Vol.1 4-18 O'
p Secti:n 4 Recycle and Disposal of Steel l- Table J.4 Values used for calculation of BOF mass partition factors (metric tons per charge)
'; Nominal High* Low'
\
Fumace input Pig iron 68 68 68 Scrap 32 32 32 :
Flux 7.8 7.8 7.8 !
Oxygen 5.9 5.9 5.9 i
! Total, t i13.7 113.7 113.7 Furnace Output
, Steel 88 95 85 l Baghouse Dust 1.2 1.3 1.2
- Slag 24.5 17.4 27.5 ,
Total, t i13.7 113.7 113.7 l
- High = Highest yield of steel (lowest production of baghouse dust and slag) !
Low = Lowest yield of steel (highest production of baghouse dust and slag) )
4.3.2 Elemental Partitioning Factors I
This section presents the basic assumptions and methodology used in developing the elemental !
partitioning factors. Section 4.3.2.3 summarizes a comparison of the estiniated partitioning j factors used in this analysis against data available in the literature. i 4.3.2.1 ' Basic Assumptions O
All the elements included in the material flow model, with the exception of the actinides and noble gases, are typically found in steel-making as components of steel scrap, alloying additions, or unwanted impurities. Sulfur, for example, is usually an unwanted impurity in steel. However, sulfur and other chalcogenides are sometimes added to alloys to produce free-machining steels.
-In general, steel making processes and operating conditions have been developed that, depending on the desired result, can maximize the retention of a particular element in the molten steel or, conversely, maximize its removal. The elemental partitioning factors determined for the material flow model are intended to be representative of the expected behavior during melting in a typical domestic EAF or BOF.
It is recognized that there will be variability in the behavior of elements during the refining of steel. For example, cesium may almost completely volatilize to the dust if a basic slag is used, but would tend to partition to both the slag and dust if a neutral or acidic slag is used (Harvey 1990). Other factors that could affect elemental partitioning factors are gas sparging, mixing, or the type of desired melt (e.g., carbon steel or stainless steel). Thus, any single partitioning value used in the material flow modeling has some associated uncertainty. In order to address this uncertainty, the partitioning values are included as variables in the uncertainty analysis'of the material flow modeling.
The primary components of a typical steel refining facility that are important to the material flow model are the primary melting chamber (the furnace) and the air pollution control system. As eO 4-19 Draft NUREG 1640, Vol. I
i l
Recycle and Disposal of Suel Section 4 l l
stated previously, the air pollution control system consists of a fabric baghouse filter. Other components of the refinery, such as ladies, tun dishes, and reheating ovens, are not important to
)
the material flow model because no phase changes occur and there is no dilution or concentration of elements. The most common type of furnace uses a basic process with a basic slag (Lankford et al.1985). Other processes, such as the use of different slagging agents, gas sparging, and mixing, can affect the partitioning of elements. However, for this study, these will not be included because their use in refineries is extremely variable and their effects are difficult to predict.
During refining, elements can partition to one or both of the main melt components (i.e., the slag and metal phases), or discharge from the furnace in the volatilized gas. Some of the elements that leave the fumace in the volatilized gas will remain in the vapor phase (off-gas) and some will condense or coalesce into particulates (dust). Elements found in coarse particulates are captured by the baghouse filter. Sr.u of the fine particles and species in the vapor phase will ,
escape in the off-gas exiting the stM A small fraction of metals and oxides that are refractory or ferrous in nature will be carried c er to the dust. Based on general knowledge of these elements in baghouse dust and actaal experience with EAF baghouse dust, a fraction of 1% was assumed to be carried over to the dust for this flow model. For example, even though iron is a ferrous element and would be expected to partition completely to the steel product, data from baghouse filter dust analyses show that iron is present in baghouse dust (EPRI 1993).
The refinery furnace is assumed to be using a basic process, i.e., basic slag, with an average temperature of about 1600 C. The average temperature of the baghouse is assumed to be 190 C.
For purposes of determining partitioning, it is assumed that the air flowing through the baghouse is cooled to this temperature. Other assumptions include those listed in Table 4.2.
4.3.2.2 General Methodology for Determining Elemental Partitioning In order to simplify the material flow modeling, elements of concern were grouped according to their elemental partitioning factors. It was assumed that all isotopes of a given element would behave identically (no isotope effects).
First, the likely chemical form of the element in question after charging the fumace was determined. For example, iron, cobalt, and nickel will remain in the metallic state as part of a solid solution in the steel. Elements that are more reactive than iron will readily form oxides (e.g., Pu, Ac, Th). The physical properties of that form, particularly boiling point, were then examined. If the boiling point of the element ofinterest is less than 1600 C, then it is assumed to volatilize from the melt or the slag. However, if the boiling point of the element ofinterest is greater than 1600 C, it is assumed to remain in the original form. Most volatilized from the furnace will form oxides before they reach the baghouse, no matter what their form at the time of volatilization. To determine if the element that volatilizes from the fumace will stay in the vapor phase or form particulates, the boiling points of the oxide of these elements were compared to the temperature of the baghouse (190 C). If the boiling point of an element is greater than 190 C, it will tend to form particulates as it cools, with a small fraction remaining in the vapor phase. If Draft NUREG-1640, Vol.1 4 20 9
1
Section 4 Recycle and Disposal of Steel the boiling point is less than 190*C the element will remain in the vapor phase with a small fraction forming particulates. For example, zinc, which is found as a metal, boils at a O* temperature well below the expected temperature in the furnace. Thus, zine is expected to partition primarily to the off-gas components. However, the boiling point of zinc oxide is well
.above 190 C, and it is expected to form particulates (dust). On the other hand H, I, and Rn are assumed to remain in the vapor phase.
In so~me cases, it is inappropriate to assume elements will appear as oxides in the baghouse. For ,
example, the partitioning of chlorine depends on the presence of alkali metals. Even though the i elemental characteristics indicate that chlorine would form a stable gas, it would likely tend to l form particulates if alkali metals are present. Based on this information, it is determined that a small fraction of chlorine would most likely form particulates.
There are some elements that were treated as special cases because certain chemical reactions occur in the furnace that do not follow the methodology presented above. These special case elements and their expected behavior are presented below.
P - oxidized by a basic slag and volatilizes as an oxide C -
alloys with steel (with more oxygen it will tend to volatilize)
Se - generally difficult to remove from steel Sb - readily alloys with steel and is difficult to remove Mn- used extensively in the steel industry for desulfurization and reacts with sulfur to form
,. m MnS 2which forms as inclusions in the steel melt.
Na - very reactive and readily forms oxides. Because of the temperature at which Na2O (V) sublimes it will only partially volatilize from the slag.'
Tc - alloys with steel and is difficult to remove.2 Ru - alloys with steel and is difficult to remove.2 Bi - reactive and readily forms oxides. Because of the temperature at which Bi2 03 decomposes it will only partially volatilize from the slag.
K - very reactive and readily forms oxides but decomposes at a low temperature and will volatilize in the elemental form.
Pb - normally less reactive than iron. With the addition of oxygen it will form oxides and volatilize.
Table 4.5 lists elemental partitioning factors for each element in the anlaysis. For many elements there is sufficient data to identify a most likely value within this range. In probabilistic calculations, these are described using a triangular distribution with the mode equal to the most likely value. For some elements, the data do not allow a best estimate to be chosen from the ranges in the table. Partitioning of these elements is described by a uniform distribution of values across the ranges with maxima and minima, as shown in the table. Information on the uncertainty distributions for this parameter appears in Appendix B, Table B.3.
' Personal communication. G. L Leatherman, Science Applications International Corporation,1995.
2 Personal communication. A. Murray, Science Applications International Corporation.1995.
4-21 Draft NUREG 1640, Vol. I
Recycle and Disposal of Steel Section 4 Table 4.5 Elemental partitioning factors (EPF) for steel Elemental partitioning factors (%)
, Element Metal product Baghouse dust Slag Volatile Ag, C, Co, Cu, Mo, Ni, Ru, Tc 95-100 0-2 0-1 0 Sb 80-100 0-1 0-20 0 Se 0-80 0-80 20-77 0 Fe 95-100 0-2 0-5 0 Pb 0-5 95-100 0-5 0 Zn 0-20 80-100 0-1 0 Cd, Cs, Po 0-1 95-100 0-5 0 S 0-20 4-97 0-3 0 Re 0-99 l-97 3-87 0 P 0-10 4-97 3-77 0 K 0-1 50-100 3-50 0 Ir 0-100 0-100 0-3 0 Bi 0-25 45-100 0-25 0-5 Mn 24-50 0-4 50-75 0 Cr 49-99 0-1 0-50 0 Na 0-10 40-50 45-55 0-5 Ra 0-5 0-5 95-100 0 Ac, Am, Ba, Ca, Ce, Cm, Eu, Nb, Np, Pa, Pm, 0-1 0-5 95-100 0 Pu, Sr, Sm, Th, U, Y, Zr Cl 0-1 8-50 0-50 0-90 1, Rn 0 0 0 100 H 0-10 0 0 90-100 EPF = [ element concentration in product / clement concentration in scrap]x 100 Partitioning factors are not sampled to ensure that they add up to 1.0 for any single run within a probabilistic calculation. This is not necessary for the purpose of this anlaysis because each scenario calculates dose from exposure to only one material at a time.
4.3.2.3 Comparison of Partitioning Factors with Published Studies A comparison of the partitioning factors presented above to experimental information on partitioning was done in order to help establish their validity. The comparison was limited to those studies that presented results from actual experimental meltings of radioactively contaminated metal. One exception to this was Copeland (Copeland et al.1978) who used a non-experimental thermodynamic approach similar to this study. However, dust was not included in the Copeland study, and elements were partitioned between slag and the metal product only.
Articles that did not present enough data to determine partitioning were not included. The literature reviewed had information on only a limited number of elements-most commonly cobalt and cesium- probably because these are most likely to be involved in accidental melting of sealed sources.
In general, the results presented in previous studies support the grouping and partitioning factors developed herein. Even though partitioning values do not agree exactly, the overall grouping is supported. The differences between the previous studies and partitioning factors and groupings developed for this study are mainly due to the different assumptions used (e.g., type of furnace l used, pumose of refining). The purpose of some experiments was to decontaminate the metal i Draft NUREG-1640, Vol.1 4-22 i
l I
Section 4 Recycle and Disposal of Steel and force the radionuclides to the slag. This is different than the assumption used in this report
('dp) -(normal refining operations and no decontamination). In some cases the assumptions used were not stated in the study, so an accurate interpretation and comparison of the partitioning data was impossible.
4.4 Mathematical Model for Flow of Recycled Steel Scrap This section presents the equations that comprise the mathematical model of the information presented previously in Sections 4.2 and 4.3. The equations are used to estimate radionuclide concentrations in refined steel and other co-products of refining. For calculation, the equations are entered in spreadsheets that have been organized and structured specifically for this analysis.
The calculated radionuclide concentrations in refined steel, refinery slag, refinery baghouse dust, and the activity released out the refinery stack are used as input to the scenario analyses described in Section 4.6.
4.4.1 Scrap Mixing There are two processes by which the original concentration of each radionuclide in steel, scrap is potentially changed. The first can occur upon mixing with other scrap metal prior to refining.
This mixing is a radionuclide-independent process, so the radioactivity concentration of all radionuclides is affected the same when mixing with a given mass of non-contaminated scrap steel. The second process is the refining process itself, which generally consists of the melting of
,g steel scrap metal and the resulting redistribution (partitioning) of mass and radioactivity.
I $
Partitioning of mass during refining is radionuclide-independent, however partitioning of U radioactivity during refining is element-dependent. The following equations are used to calculate j the radionuclide concentrations in refinery co-products at those points in the material flow which ;
correspond to potential exposure scenarios. h 1
1 The first change in radioactivity concentration occurs if the cleared scrap from the nuclear l facility is mixed with other metal prior to melting. There are actually two potential places that l mixing can occur: at the scrap dealer (i.e., secondary metal pool) and in the primary metal pool j at the refinery furnace. For simplicity, these two mixings were treated as a single potential i dilution. This mixing is modeled using appropriate ranges for the masses of cleared and other scrap entering a refinery fumace. These masses were derived for both EAFs and BOFs and are listed in Appendix B. The total mass of scrap entering the furnace in a year was calculated using Equation 4.1.
M, = Mo+ M yc 4.1 where Mi = total mass of scrap metal entering the furnace per charge (g/ charge) and V 8
= mass of cleared material entering the furnace per charge (g/ charge)
M.
Msc = mass of non-contaminated scrap metal entering the furnace per charge (g/ charge)
D b 4 23 Draft NUREG-1640, Vol.1
.l Recycle and Disposal of Steel Section 4 The radionuclide concentration in the metal entering the furnace was calculated using ;
Equation 4.2. The original radioactivity concentration, Co, is reduced by the ratio of the mass of i cleared scrap entering the furnace to the total mass of material entering the furnace. The following equations are intended to be evaluated separately for each radionuclide in the analysis.
However, parameters such as concentration and other radionuclide-specific parameters are not explicitly subscripted in the equations.
M i C' - M, .C 4.2 where Ci =
radionuclide concentration in scrap entering the refining process (pCi/g) and
=
Mo mass of cleared material entering the furnace per charge (g/ charge)
Mi =
total mass of scrap metal entering the furnace per charge (g/ charge)
C. =
original radionuclide concentration in cleared material (pCi/g)
For slag, baghouse dust, and off-gas, Equatio'ns 4.1 and 4.2 were evaluated using annual average values for the masses of scrap input to the furnaces, because all of the exposure scenarios for these materials depend on annual average radionuclide concentrations. For metal, both an annual average and a single charge evaluation of Equations 4.1 and 4.2 were conducted. This was d,ne for metal because there are metal products that could easily be manufactured from a single refinery charge. The single charge radionuclide concentrations were used in metal product use exposure scenarios except where noted. (See Appendix D for additional details.)
4.4.2 Refinery Process
- To accurately account for the changes in radionuclide concentration in the different products, the mass ofeach refinery product must be calculated independent of radionuclide activity. Equations 4.3,4.4, and 4.5 were used to calculate the masses of slag, dust, and metal product, respectively.
M, = M, f,, . CPY 4.3 M, = M, f,, . CPY 4.4 M, = M, ef,, CPY 4.5 Draft NUREG-1640, Vol.1 4-24 O
Section 4 ' ' Recycle and Disposal of Steel where O M, M,
M,
=
=
= mass of slag produced from a refinery per year (g) mass of dust produced from a refinery per year (g) mass of metal product produced from a refinery per year (g) and M, = total mass of scrap entering the fumace per charge (g/ charge) f,c ~ = mass partitioning factor for slag during the refining process (dimensionless)
- f. , = mass partitioning factor for dust during the refining process (dimensionless) f,, =
mass partitioning factor for metal product during the refining process (dimensionless)
CPY = number of charges per refinery per year (charge)
The radioactivity in the original scrap metal entering the furnace during the refining process is partitioned into four products. Equation 4.6 shows the calculation of the concentration of radionuclides in slag, taking into account both the mass and elemental partitioning factors.
C,*f,. M, C, f, C= =
4.6 M, e f, f, where C, =
radionuclide concentration in slag after the refining process (pCi/g) and C, = radionuclide concentration in scrap entering the refining process (pCi/g) f, = slag elemental partitioning factor during the refining process (dimensionless)
M, =
total mass of scrap entering the fumace per charge (g/ charge) f., = mass panitioning factor for slag during the refining process (dimensionless)
The concentration of radionuclides in the dust and metal product are calculated using Equations 4.7 and 4.8, respectively.
C, . f, C= 4.7 ldt where C, = radionuclide concentration in dust after the refining process (pCi/g) and C, =
radionuclide concentration in scrap entering the refining process (pCi/g) f, = dust elemental partitioning factor during the refining process (dimensionless) f,, = mass partitioning factor for dust during the refining process (dimensionless)
C, . f C-'
P 4,g lpt where C, = radionuclide concentration in metal product after the refining process (pCi/g) b, 4-25 Draft NUREG-1640, Vol.1 i
Recycle and Disposal of Steel Section 4 l and C, = radionuclide concentration in scrap entering the refining process (pCi/g) f, = metal product elemental partitioning factor during the refining process (dimensionless) f,i = mass partitioning factor for metal product during the refining process (dimensionless)
Because there is no mass associated with the refinery off-gas, the total quantity of radioactivity was calculated instead of a concentration. The off-gas radioactivity was calculated using Equation 4.9 using only the elemental partitioning factor (i.e., no mass partitioning factor). This radioactivity is calculated on an annual basis. ,
A, = C, . M,
- f, = CPY 4.9 where A, = radioactivity in the off-gases leaving the refinery stack in a year (pCi) and Ci = radionuclide concentration in scrap entering the refining process (pCi/g)
M, = total mass of scrap entering the fumace per charge (g/ charge) f, = off-gas elemental partitioning factor during the refining process (dimensionless)
CPY = number of charges per refinery per yea-(charge)
Equations - 1 and 4.11 were used to calculate the mass of dust that escapes the baghouse filters, and that wE is captured in the baghouse, respectively.
M,, = M, * ( 1 - BHg ) 4.10 where M. - total mass of dust that escapes the baghouse in a year (g) and M. = mass of dust produced from the refining process in a year (g)
BH, = baghouse efficiency (dimensionless)
M ,,- M ,- M ,, 4.11 where M. = total mass of dust captured in the refinery baghouse in a year (g) and M. = mass of dust produced from the refining process in a year (g)
M. = total mass of dust that escapes the baghouse in a year (g) i l
Draft NUREG-1640, Vol.1 4-26 9i
r l
Section 4 Recycle and Disposal of Steel l
'4.4.3 EAF Dust Hazardous Landfill ;
l A certain percentage of the EAF dust produced by the steel industry each year is treated for direct l disposal in a hazardous landfill. During this immobilization treatment, dilution of the EAF dust
~
l is the only process modeled. The mass of EAF dust that L, sent to hazardous landfills in a year is ,
represented by Equation 4.12. The total mass of matenal entering the immobilization process in !
l a year is calculated using Equation 4.13. The radioactivity concentration in the treated dust when it is placed in a hazardous landfill is calculated using Equation 4.14.
Mg= M,, fg 4.12 l
M,g Wu,,, Mg 4.13 l
Cy - C, . gy 4.14 l
l where
= mass of contaminated EAF dust sent to a hazardous landfill in a year (g)
Ms M, = total mass of material entering the immobilization process in a year (g)
Cs = radionuclide concentration in immobilized dust (pCi/g)
M. = total mass of dust captured in the refinery baghouse in a year (g) .
=
fa annual fraction of total EAF dust that it sent to hazardous landfills (dimensionless)
Mw = mass of additives used in the immobilization process in a year (g)
C, = radionuclide concentration in dust after the refining process (pCi/g) dfs = dilution factor for immobilization process (dimensionless) 4.5 Radioactivity Concentrations in Steel Refining Co-products The values listed in Table 4.6 are calculated radioactivity concentrations at an EAF refinery and Table 4.7 for a BOF refinery. The values are normalized to a unit radioactivity concentration in scrap, and are listed in S.I. units. The values are numerically identical if expressed in conventional units (e.g., pCi/g product per pCi/g scrap).
1 4.6 Dose Assessment for Steel Recycle and Disposal 4.6.1 General Description of Recycle Scenarios General categories of scenarios were established to organize and simplify the evaluation and I analysis of potential exposure scenarios. Because of the logical link between material flow l l models and potential exposure scenarios, the categories were derived from the steel scrap l
material flow model (Figure 4.1). Analysis of material characteristics and human behavior at l p certain points in the flow model identified six logical scenario categories for the evaluation: )
l 4-27 Draft NUREG-1640, Vol. l
Recycle and Disposal of Steel Section 4 l
handling and processing (individual atmospheric releases), storage, product use, trasportation, disposal activities, and resident on closed landfill scenarios.
Exposure conditions for scenarios not in these identified categories would be similar to those in j the selected categories, and can be reasonably approximated by the evaluation of the categories {
chosen for evaluation. Consistent with the goals of the analysis, the exposure categories were !
selected to simplify the evaluation without limiting its comprehensiveness.
The following sections briefly describe the exposure pathways included in the recycle scenario analyses, followed by a description of the six general categories that the exposure scenarios fall into. Starting with handling at a scrap yard, through processing and use, to disposal and post-closure of a landfill, the categories encompass a " cradle to grave" picture of recycle of steel 3 '
cleared from a NRC licensed facility. The scenarios can be divided into two broad categories:
work-related and non-work-related. Work related exposure scenarios, obviously, would be limited to workers exposed to recycled material during the course of their workday. Non-work-related exposure scenarios describe situations where the general public might come in contact with recycled material as consumers or as part of daily activities not directly associated with employment. Some scenario categories contain both worker and non-worker exposure scenarios.
There are 31 exposure scenarios listed in Table 4.8. Of these, only 27 were used for the determination of critical groups. The four landfill resident scenarios werejudged to be too unlikely to use in the critical group determination, but were analyzed for completeness. A summary of the highest mean dose factors for the landfill resident scenarios is included in Appendix J.
Table 4.6 Results of material flow model-steel electric arc furnace Mean radionuclide concentrations in refinery products (Bq/g per Bq/g scrap)
Refined metal Off-gas Nuclide Single charge Annual Slag Dust (Bq per Bq/g)
H-3 3.1E-02 2.3E-03 0.0E+00 0.0E+00 3.4 E+ 10 C-14 9.2E-01 7.0E-02 1.5 E-03 4.3 E-02 0.0E+00 Na-22 3.lE-03 2.3 E-04 2.lE-01 1.9E+00 1.2E+09 P-32 3.2E-02 2.4E-03 1.9E-01 2. l E+00 0.0E+00 S-35 9.4E-02 7.0E-03 1.6E-01 2.2E+00 0.0E+00 Cl-36 6.2 E-03 4.7E-04 1.0E-01 1.3 E+00 1.6E+10 K-40 3.lE-03 2.4E-04 1.lE-01 3.2E+00 0.0E+00 Ca-41 3.IE-03 2.4E-04 4.1E-01 8.6E-02 0.0E+00 Ca-45 3.2E-03 2.4 E-04 4.IE-01 8.3 E-02 0.0E+00 Cr-51 7.0E-01 5.2E-02 1.lE-01 2.9E-02 0.0E+00 Mn-54 3.5E-01 2.6E-02 2.6E-01 7. l E-02 0.0E+00 Fe-55 9.1E-01 6.9E-02 9.7E-03 4.3 E-02 0.0E+00 Co-57 9.2E-01 7.0E-02 1.4E-03 4.3 E-02 0.0E+00 Co-58 9.2E-01 7.0E-02 1.4E-03 4.3 E-02 0.0E+00 Fe-59 9.1E-01 6.9E-02 9.6E-03 4.3 E-02 0.0E+00 Ni-59 9.2E-01 7.0E-02 1.4E 03 4.3 E-02 0.0E+00 Co-60 9.2E-01 7.0E-02 1.3 E-03 4.3 E-02 0.0F Q Draft NUREG-1640, Vol. I 4-28
g I
Section 4 Recycle and Disposal of Steel j i
Table 4.6 Results of material flow modeLs.tect electric are furnace
.j j Mean radionuclide coacentrations in refinery produc*s (Bq/g per Bq/g scrap)
,Q Refined metal Off-gas l Nuclide Single charge Annual Slag Dust (Bq per Bq/g) l - Ni 9.2E-01 7.0E-02 1.4E-03 4.2E-02 0.0E+00 l Zn-65 9.4E-02 7.0E-03 1.4E-03 3.9E+00 0.0E+00 l Cu-67 9.2E-01 7.0E-02 1.4E-03 4.4E-02 0.0E+00 l Se-75 3.8E-01 2.9E-02 2.0E-01 1.7E+00 0.0E+00
! Sr-85 3 lE-03 2.4E-04 4.lE-01 8.5E-02 0.0E+00 Sr-89 3.lE-03 2.4E-04 4.lE-01 8.8E-02 0.0E+p0 l
l Sr-90 3.1E 2.4E-04 4.1E-01 8.6E-02 0.0E+00 l Y-91 3 2E-03 2.5E-04 4.1E-01 8.5E-02 0.0E+00 l- Mo-93 9.2E-bl 7.0E-02 0.0E+00 1.4E-03 4.3 E-02 Nb-93m 3.lE-03 '2.3E-04 4.lE-01 8.7E-02 0.0E+00
- . Nb-94 3.1E-03 2.4E-04 4.1E-01 8.6E-02 0.0E+00 Nt> 95 3.1E-03 2.4E-04 4.IE-01 8.6E-02 0.0E+00 i Zr-95 -3.1E-03 2.4E-04 4.1E-01 8.6E-02 0.0E+00 l Tc 99 9.2E-01 7.0E-02 1.4E-03 4.3E-02 0.0E+00 Ru-103 9.2E-01 7.0E-02 1.4E-03 4.3 E-02 0.0E+00 Ru-106 9.2E-01 7.0E-02 1.4E '3 4.3E-02 0.0E+00 i I Ag-108m 9.2 E-01 7.0E-02 1.3 E-03 4.3E-02 0.0E+00 Cd-l09 3.1E-03 2.3E-04 1.1E-02 4.2E+00 0.0E+00 Ag-110m 9.2F-01 7.0E-02 1.4 E-03 4.4 E-02 0.0E+00
,q Sb-124 8.5 E-01 6.4E-02 4.lE-02 1.4 E-02 0.0E+00 .
i 1-125 0.0E+00 0.0E+00 0.0E+00 0.0E+00 3.6E+19
)
Sb-125 8.5E-01 6.4 E-02 4.2E-02 1.4E-02 0.0E+00 1-129 0.0E+00 0.0E+00 0.0E+00 0.0E+00 3.6E+10 1 131 0.0E+00 0.0E+00 0.0E40 0.0E+00 3.6E+10 Ba-133 3.2E-01 2.4E-04 4.lE 01 8.5E-02 0.0E+00 1 Cs-134 3.1E-03 2.3E-04 1.IE-02 4.2E+00 0.0E+00 Cs-137 3.2E-03 2.3E-04 1.lE-02 4.2E+00 0.0E+00 Co-141 3.1E-03 2.4E-04 4.1E-01 8.?E-02 0.0E+00 Cc-144 3.lE-03 2.4E-04 4.lE-01 8.4E-02 0.0E+00 Pm 147 3.2E-03 2.5E-04 4.lE-01 8.7E-0.2 0.0E+00 Eu-152 3.lE-03 2.4E-04 4.lE-01 8.4E-02 0.0E+00 Eu-If 4 3,1E-03 2.4E-04 4.1E-01 8.7E-02 0.0E+00 Eu-155 3.2E-03 2.4E-04 . 4.lE-01 8.7E-02 0.0E+00 l
Re-186 4.6E-01 3.5E-02 8.3E-03 2.1 E+00 0.0E+00 Ir-192 4.7E-01 3.7E-02 8.4 E-03 . 2.2E+00 0.0E+00 Pb-210 2.2E-02 1.7E-03 9.6E-03 4.2E+00 0.0E+00 Po-210 3.lE-03 2.3E-04 1.lE-02 4.2E+00 0.0E+00 Bi-210 1.2E-01 8.8E-03 5.2E-02 3.2E+00 1.2E+09 Rn-222 0.0E100 0.0E+00 0.0E+00 0.0E+00 3.6E+ 10 Ra-223 - 1.9E-02 1.5E-03 4.lE-01 8.6E-02 0.0E+00 i Ra-224 1.9E-02 1.4E-03 4.lE-01 8.6E-02 0.0E+00 V 4-29 Draft NUREG 1640, Vol.1 l
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Recycle and Di;posal of Steel Section 4 Table 4.6 Results of material flow model-steel electric are furnace Mean radionuclide concentrations in refinery products (Bq/g per Bq/g scrap)
Refined metal Off-gas Nuclide Single charge Annual Slag Dust (Bq per Bq/g)
Ac-225 3.lE-03 2.4 E-04 4.lE-01 8.6E-02 0.0E+00 Ra-225 1.9E-02 1.5E-03 4.lE-01 8.6E-02 0.0E+00 Ra-226 1.9E-02 1.4 E-03 4.1E-01 8.8E-02 0.0E+00 Ac-227 3.lE-03 2.3 E-04 4.l E-01 8.7E-02 0.0E+00 Th-227 3.lE-03 2.4E-04 4.lE-01 8.7E-02 0.0E+00 Th-228 3.1E-03 2.3 E-04 4.IE-01 9.0E-02 0.0E+00 Ra-228 1.9E-02 4.lE-01 1.4 E-03 8.4E-02 0.0E+00 )
Th-229 3.lE-03 2.4 E-04 4.lE-01 8.5E-02 0.0E+00 I Th-230 3.lE-03 2.4E-04 4.lE-01 8.6E-02 0.0E+00 I Pa-231 3.2E-03 2.3E-04 4.lE-01 8.5E-02 0.0E+00 Th-231 3.2E-03 2.4E-04 4.lE-01 8.8E-02 0.0E+00 Th-232 3.lE-03 2.3 E-04 4.lE-01 8.7E-02 0.0E+00 ,
Pa-233 3.IE-03 2.3 E-04 4.lE 01 8.6E-02 0.0E+00 {
U-233 3.2E-03 2.4E-04 4.lE-01 8.8E-02 0.0E+00 Th-234 3.1E-03 2AE-04 4.1E-01 8.5E-02 0.0E+00 U-234 3.2E-03 2.4 E-04 4. l E-01 8.6E-02 0.0E+00 U-235 3.2E-03 2.4 E-04 4.1E-01 8.7E-02 0.0E+00 Np-237 3. l E-03 2.4E-04 4.lE-01 8.4 E-02 0.0E+00 Pu<238 3.lE-03 2.4E-04 4.!E-01 8.5E-02 0.0E+00 U-238 3.lE-03 2.4E-04 4. l E-01 8.6E-02 0.0E+00 Pu-239 3.lE-03 2.4 E-04 4.lE-01 8.5E-02 0.0E+00 Pu-240 3.IE-03 2.4E-04 4.1E-01 8.5 E-02 0.0E+00 Pu-241 3.2E-03 2.3 E-04 4.lE-01 8.5E-02 0.0E+00 Am-241 3.2E-03 2.3 E-04 4. l E-01 8.3 E-02 0.0E+00 Cm-242 3.lE-03 2.4E-04 4.!E-01 8.5E-02 0.0E+00 l Pu-242 3.2E-03 2.3 E-04 4. l E-01 8.5E-02 0.0E+00 l
Cm-244 3.2E-03 2.4 E-04 4. l E-01 8.8E-02 0.0E+00 !
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i Draft NUREG-1640, Vol.1 4-30 l
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Section 4 Recycle and Disposal of Steel
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> Table 4.7 Results of material now model-for steel basic oxygen furnace ,
s) Mean radionuclide concentrations in refinery products (Bq/g per Bq/g scrap) l O Refined metal Off-gas Nuclide Single charge Annual Slag Dust (Bq per Bq/g)
H-3 1.0E-02 6.9E-03 0.0E+00 0.0E+00 2.2E+ 10 l C-14 3.0E-01 2.0E-01 2.6E-03 1.5E-01 0.0E+00 Na-22 1.0E-03 6.7E-04 4.0E-01 6.6E+00 7.7E+08 P-32 1.0E-02 6.7E-03 3.7E-01 7.2E+00 0.0E+00 l S-35 3.0E-02 2.0E-02 3.3E-01 7.3E+00 0.0E+00 Cl-36 2.0E-03 1.4E-03 2.0E-01 4.3 E+00 1.1E+10 K-40 1.0E-03 6.8E-04 2.lE-01 1.lE+01 0.0E+00 Ca-41 1.0E-03 6.8E-04 7.9E-01 3.0E-01 0.0E+00 l l Ca-45 1.0E-03 6.7E-04 7.9E-01 3.0E-01 0.0E+00 i
! Cr-51 2.2E-01 1.5E-01 2.0E-01 9.7E-02 0.0E+00 l
! Mn-54 1.1E-01 7.7E-02 5.0E-01 2.4E-01 0.0E+00 Fe-55 2.9E-01 2.0E-01 1.9E-02 1.5E+00 0.0E+00 Co-57 3.0E-01 2.0E-01 2.7E-03 1.5L-01 0.0E+00 ,
Co58 3.0E-01 2.0E-01 2.7E-03 1.4 E-01 0.0E+00 I l Fe-59 2.9E-01 2.0E-01 1.9E-02 1.4E+00 0.0E+00 l Ni-59 3.0E-01 2.0E-01 2.6E-03 1.5E-01 0.0E+00 Co-60 3.0E-01 2.0E-01 2.7E-03 1.5E-01 0.0E+00 Ni-63 3.0E-01 2.0E-01 2.7E-03 1.5E-01 0.0E+00 Zn-65 3.0E-02 2.0E-02 2.7E 03 1.3 E+01 0.0E+00 l O ~
Cu-67 3.0E-01 2.0E-01 2.7E-03 1.4E-01 0.0E+00 l Se-75 1.2E-01 8.2E-02 3.9E-01 5.8E+00 0.0E+00
- Sr-85 1.0E-03 6.8E-04 7.9E-01 3.0E-01 0.0E+00 l Sr-89 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+00 Sr-90 1.0E-03 7.IE-04 7.9E-01 2.9E-01 0.0E+00 I Y-91 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00
! Mo-93 3.0E-01 2.0E-01 2.7E-03 1.5E-01 0.0E+00
- Nb 93m 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 0.0E+00 Nb-94 1.0E-03 6.9E-04 7.9E-01 3.0E-01 Nb-95 1.0E-03 7.0E-04 7.9E-01 3.0E-01 0.0E+00
- Zr-95 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 Tc-99 3.0E-01 2.0E-01 2.6E-03 1.4E-01 0.0E+00 l Ru-103 3.0E-01 2.0E-01 2.6E-03 1.5E-01 0.0E+00 Ru-106 3.0E-01 2.0E-01 2.7E-03 1.4E-01 0.0E+00 l Ag-108m 3.0E-01 2.0E-01 2.7E-03 1.5E-01 0.0E+00 l Cd-109 1.0E-03 6.9E-04 2.lE-02 1.4E+01 0.0E+00 Ag-11Om 3.CE-01 2.0E-01 2.7E-03 1.5E-01 0.0E+00 Sb-124 2.7E-01 1.9E-U l 8.2E-02 4.7E-02 0.0E+06 I-125 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.3 E+10 Sb-125 2.7E-01 1.9E-01 7.9E-02 4.8E-02 0.0E+00 1-129 0.0E+00 0.0E+00 0.0E+ 00 0.0E+00 2.3E+10 l 131 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.3E+10 Ba 133 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+00
/~N Cs-134 1.0E-03 6.9E-04 2.lE-02 1.4E+01 0.0E+00 4-31 Draft NUREG-1640, Vol. I k
Recycia and Disposal of Steel Section 4 Table 4.7 Results of material flow model-for steel basic oxygen furnace
'Mean radionuclide concentrations in refinery products (Bq/g per Bq/g scrap)
Refined metal Off-gas Nuclide Single charge Annual Slag Dust (Bq per Bq/g)
Cs 137 1.0E-03 6.9E-04 2.2E-02 1.4 E+01 0.0E+00 Ce-141 1.0E-03 7.0E-04 7.9E-01 2.9E-01 0.0E+00 I Ce-144 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 f Pm-147 1.0E-03 7.0E-04 7.9E-01 3.0E-Oi 0.0E+00 Eu-152 1.0E-03 6.8 E-04 7.9E-01 2.9E-01 0.0E+00 Eu-154 1.0E-03 7.0E-04 7.9E-01 2.9E-01 0.0E+00 Eu-155 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 Re-186 1.5E-01 1.0E-01 1.6E-02 7.3 E+00 0.0E+00 Ir-192 1.5E-01 1.0E-01 1.6E~02 7.2E+00 0.0E+00 Pb-210 7.0E-03 4.8E-03 1.8E-02 1.4E+01 0.0E+00 Po-210 1.0E-03 6.9E-04 2.1E-02 1.4 E+01 0.0E+00 Bi-210 3.8E-02 2.6E-02 1.0E-01 1. l E+01 7.6E+08 Rn-222 0.0E+00 0.0E+00 0.0E+00 0.0E+00 2.3E+ 10 Ra-223 6.0E-03 4.1E-03 7.9E-01 3.0E-01 0.0E+00 Ra-224 6.0E-03 4.lE-03 7.9E-01 3.0E-01 0.6E+00 Ac-225 1.0E-03 6.7E-04 7.9E-01 2.9E-01 0.0E+00 i Ra-225 6.0E-03 4.1E-03 7.9E-01 2.9E-01 0.0E+00 Ra-226 6.lE-03 4.0E-03 7.9E-01 2.9E-01 0.0E+00 Ac-227 9.8 E-04 6.7E-04 7.9E-01 2.9E-01 0.0E+00 Th-227 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 Th-228 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 ,
Ra-228 6.IE-03 4.2E-03 7.9E-01 3.0E-01 0.0E+00 Th-229 1.0E-03 7.0E-04 7.9E-01 2.9E-01 0.0E+M Th-230 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+0,,
Pa-231 1.0E-03 6.8E-04 7.9E-01 3.0E-01 0.0E+00 Th-231 1.0E-03 7.0E-04 7.9E-01 3.0E-01 0.0E+00 Th-232 1.0E-03 6.9E-04 7.9E-01 3.0E-01 0.0E+00 Pa-233 1.0E-03 6.7E-04 7.9E-01 2.9E-01 0.0E+00 U-233 1.0E-03 6.7E-04 7.9E-01 2.9E-01 0.0E+00 7h-234 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 U-234 9.9E-04 6.9E-04 7.9E-01 2.9E-01 0.0E+00 U 235 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+00 Np-237 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+00 Pu-238 1.0E-03 6.8E-04 7.9E-01 2.9E-01 0.0E+00 U-238 1.0E-03 7.0E-04 7.9E-01 3.0E-01 0.0E+00 Pu-239 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 Pu-240 1.0E-03 7.1E-04 7.9E-01 2.9E-01 0.0E+00 j Pu-241 1.0E-03 7.1E-04 7.9E-01 3.0E-01 0.0E+00 {
Am-241 1.0E-03 6.8E-04 7.9E-01 2.8E-01 0.0E+00 j Cm-242 1.0E-03 6.9E-04 7.9E-01 2.9E-01 0.0E+00 i Pu-242 1.0E-03 7.1E-04 7.9E-01 3.0E-01 0.0E+00 Cm-244 1.0E-03 6.7E-04 7.9E-01 2.9E-01 0.0E+00 Draft NUREG-1640, Vol.1 4 32 0
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Section 4 Recycle and Disposal of Steel Table 4.8 Scenario and exposure pathway matrix O
_ _ ~
Exposure pathways
- Scenario title and abbreviation for steel Ext inh Sec DW Ing Handling and Processing Scenarios Handling scrap metal at the scrapyard, FE-SCRP-HANDLIN W I ee l
Handling slag at the refinery, FE-SLAG-HANDLIN-W F1 e e l Refimery baghouse operations, FE-EAFD-BAGHOUS-W 8 ee Handling EAF dust at the refinery, FE EAFD-HANDLIN-W 9 ee l
Handling refined metal product at the refinery, FE-METL-HANDREF-W 2 ee Handling BOF refined metal during product manufacturing, FE BOFM-HANDMAN-W 2 ee Handling EAF refined metal product during distribution, FE-METL-HANDDIS-W 2 Processing EAF dust for disposal, FE-EAFD-PROCESS-W I eo Processing slag for use as aggregate or as roadbed, FE-SLAG-PROCESS-W l e e Atmospheric release during refining, FE-ATMO-REFINER-N F2 e o e Storage Scenario l Storage of slag at the refinery, FE-SLAG-STORAGE-N e
~ ~ - ~ '
Transport Scenarios
~ - ~ ~
! Transport of scrap metal, FE-SCRP-TRANSPO-W 4 Transport of slag, FE-SLAG-TRANSPO-W 4 Transporltuntreated EAF dust, FE-EAFD-TRANSPO-W 4 Transport of refined metal product, FE-METL-TRANSPO-W 4 Disposal Scenarios Disposal of BOF dust in a sanitary landfill, FE-BOFD-DISPOSL.W F1 ee l
i Disposal of refinery slag in a sanitary landfill, FE-SLAG DISPOSL-W F1 ee
~
! Disposal of scrap metal in a sanitary landfill, FE-SCRP-DISPOSL-W F1 l Disposal of EAF dust in a hazardous waste landfill, FE-EAFD-DISPOSL-W Fl Product Use Scenarios Road constmetion activities using refinery slag, FE-SLAG-ROADBED-W F1 ee In proximity of a large metal mass, FE-METL-LGMASS-N 2 in proximity of a small metal mass, FE METL-SMMASS-N 3 Small steel mass close to the body, FE-METL-SMOBJCT-N 6 Inside an automobile, FE-METL-VEHICLE-N 11 Inside a building structure, FE-METL-BLDGSTR-N 10 l Use of slag as aggregate in basement construction, FE-SLAG-CONCBAS-N 7 Use of slag in a roadbed, FE-SLAG-ROADBED-N Fi 4-33 Draft NUREG-1640, Vol.1
Recych and Dispos:1 of Ste:I Section 4 Table 4.8 Scenario and exposure pathway matrix Exposure pathways'
~
Scenario title and abbreviation for steel ~5xt" Inh"Sec Uin~g ,
Landfill Resident Scenarios Resident on a closed landfill after disposal of DOF dust, FE-BOFD-LANDFIL-N
~
F1 e e i i Resident oniclosed landfill after disposal of refinery slag [fEI 557Ali-LANDFIL-N F1 e e o
~
Resident on a closed landfill after disposal of scrap metai~EE'.56RP-LANDFIL-N F1 e e e !
i Resident on a closed landfill after disposal of EAF dust, FE-EAFD-LANDFIL-N F1 e o e 1
- a. Ext = extemal, Inh = inhalation, Sec = secondary ingestion, Ing = ingestion of food (plants), DW = drinking water ingestion. >
- b. These landfill resident scenarios were analyzed, but were not included in the determination of critical groups. A dose summary is included in Appendix 1 1 Extemal dose based on geometry factor #1 (large pile) 2 External dose based on geometry factor #2 (large metal object) 3 External dose based on geometry factor #3 (small metal object) 4 Extemal dose based on geometry factor #4 (driver of truck) 5 Extemal dose based on geometry factor #5 (beside tmck) 6 Extemal dose based on geometry factor #6 (small metal object close to body) 7 Extemal dose based on geometry factor #7 (inside a structure) 8 External dose based on geometry factor #8 (inside refinery baghouse) 9 External dose based on geometry factor #9 (on top of bag house dust truck) 10 Extemal dose based on geometry factor #10 (steel-framed structure) 11 Extemal dose based on geometry factor #1 I (inside an automobile)
F1 External dose based on Federal Guidance Report # 12 values (soil contaminated to an infinite depth)
F2 Extemal dose based on Federal Guidance Report # 12 values (contaminated ground surface)
Exposurepathways: The characteristics and behavior of the radionuclides in recycled material will also determine the potential exposure pathways. For example, gamma-emitting radionuclides will present an external exposure potential, whereas alpha-emitting radionuclides will not. Three main exposure pathways have been identified for this study: external exposure, inhalation, and ingestion. Each pathway has been subdivided into more specific pathways for modeling purposes. Exposure scenarios were modeled by combinations of various exposure pathways. The exposure pathways that were included in each exposure scenario are shown in Table 4.8.
Each scenario description includes an identification of the pathways most likely to result in exposure to the individual (s) evaluated. Although other exposure pathways for many of the scenarios are theoretically possible, they were not included because the probability of them occurring to a significant extent is very low. For example, doses resulting from external exposure to resuspended dust would be insignificant compared to doses from external exposure to the volume source itself. Those pathways that are unlikely--or that represent comparatively insignificant exposure-are not included.
Draft NUREG-1640, Vol. I 4-34 O
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Section 4 J .. Recycle and Disposal of Steel Githe many possible exposure pathways that could be identified for reuse and recycle exposure O scenarios, a comprehensive set of five potentially important pathways has been used for this analysis. The five exposure pathways are described below.
Erterna' exposure to penetrating radiation-The source material containing radionuclides that emit penstrating radiation can include volume sources, such as piles of scrap metal or slag, refinery baghouse structures, large or small metal products made from refined steel, or transport
. containers. Plane sources, such as from disposed metal, baghouse dust, or slag are also iucluded.
I Inhalation exposure to airbn.se radionuclides-This pathway includes inhalation of material !
resuspended from surfaces dering handling, processing, and disposal activities; atmospheric releases from refineries; and selected product use activities. Source material includes dust, soil slag, and fine particulates from metal-cutting operations.
Secondary ingestion ofsurface contamination-This exposure pathway addresses inadvertent' ingestion of surface sources of material (dust, soil, slag, and metal shavings). Except for two exceptions, this pathway is included whenever the inhalation pathway is present and is based on the same source material as the inhalation pathway. (The scenarios addressing atmospheric releases from a refinery and resident on a closed landfill do not include secondary ingestion.)
Ingestion offood andsoil-This exposure pathway is the conventional food consumption pathway (vegetables), plus direct ingestion of soil.
Drinking water ingestion-This exposure pathway addresses the consumption (ingestion) of d drinking water extracted from a groundwater source (i.e., a well). j 4.6.2 Work Related Scenarios The exposure scenario categories that are work-related are:
- handling i
- processing a storage
. product use
. transport
= disposal scenarios.
4.6.2.1 Handling Scenarios After clearance from an NRC licensed facility, if the material is for recycle or disposal, scrap and refinery byproducts (slag, dust, metal product) must be handled in a number of work-related settings. A variety of work-related conditions and practices were analyzed to identify the most likely exposure scenarios. This included investigating the details of work-related settings to develop accurate and representative scenarios and to assign realistic values (and ranges) to b
o 4-35 Draft NUREG 1640, Vol. I
Recycle and Disposal of Steel Section 4 exposure parameters. During scenario development, details were periodically re-examined to ensure that appropriate scenarios were identified and completely described.
The hand!iag scenarios analyzed for this report encompass a representative range of work-related activities associated with handling scrap and refinery byproducts in a number of work-related settings.
- Handling scrap metal at the scrapyard
- Handling slag at refinery a Refinery baghouse operations a Handling EAF dust at the mill
. Handling of refined metal product at the mill
. Handling BOF refined metal product during rnanufacturing
= Handling EAF refined metal product during distribution.
Handling Scrap Metal at the Scrapyard Following clearance from an NRC licensed facility, scrap metal would be transported to a scrap yard, where it would be unloaded, processed, and prepared for shipment to a refinery. This scenario addresses activities that require scrap yard workers to be in proximity to the scrap metal.
These activities include unloading, sorting, cutting (sizing), shredding, baling, and loading for shipment. The individual evaluated in this scenario is assumed to perform seve.al of these activities.
Cutting and shredding processes used on scrap metal can generate airborne particulates. This is a result of the mechanical and chemical (torch) techniques used on the scrap. These airborne particulates can settle and be inadvertently ingested by workers. This is the basis for including inhalation and secondary ingestion exposure pathways.
Exposure pathways: Because of the variety of operations involved at the scrap yard, internal, as well as external exposure pathways are included in this scenario evaluation.
Externah Proximity to incoming or piled scrap meta. could result in external exposure to penetrating radiation from the volume source (scrap pile). j Inhalation: The various processing methods used (e.g., cutting and shredding) could result in resuspended metal particulates from the scrap metal, resulting in inhalation exposure.
l Secondaryingestion: Suspended metal particulates created from processing could be deposited on surfaces, causing inadvertent ingestion from contaminated hands and food.
Draft NUREG-1640, Vol.1 4-36 Ol
p Section 4 Recycle and Disposalof Steel Handling Slag at the Refinery l
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V - Refinery slag is handled at the refinery in preparation for processing or use, potentially i subjecting workers to exposure. In this scenario, the slag is in a very large pile and a front-end loader ia used to move it. This would involve driving a loader around and on top of the pile. 1 Since the driver is subject to the greatest potential exposure, this is the individual evaluated. !
J J
Exposure pathways:
External: The worker would receive external exposure from the slag pile.
Inhalation: Exposure to suspended slag in the vicinity of the slag pile.
Secondaryingestion: Inadvertent ingestion of surface contamination.
Refinery Baghouse Operations Normal operations of a steel refinery require routine and non-routine maintenance of the baghouse and baghouse filters, requiring workers to spend time near the exterior of the baghouse and inside the baghouse that encloses the filters. Typical operations near the exterior of the baghouse include routine inspections of the baghouse structure, ductwork, fans, and other parts ;
of the ventilation and filter system. Typical operations inside the baghouse include inspection, n repair, and replacement of filter bags and inspection and maintenance of other components of the dust removal system, such as seals, valves, and shaker mechanisms. The individual evaluated in (V) this scenario is the worker performing routine inspections and maintenance, as well as non-routine operations, in and around the refinery baghouse.
A larger percentage of the charge at an EAF refinery would be comprised of scrap metal than would be the case at a BOF refinery, and dust produced by an EAF would be higher in concentration for all radionuclides. Therefore, the baghouse at an EAF refinery is the case analyzed and it bounds the exposure at BOF refineries.
The inside of a baghouse represents a hazardous environment. The presence of airbome baghouse dust in a confined and congested area requires that precautions be taken, such as use of protective clothing and a respirator. This scenario assumes a respirator is used. Volatile and entrained particulate radionuclides in the effluent would be trapped on the filters, presenting a possible source of exposure to the individuals involved in baghouse operations.
Exposurepathways:
External: Expostne to penetrating radiation from the dust on the baghouse filters.
Inhalation: Exposure to resuspended dust in the baghouse.
e \
4-37 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 Secondaryingestion: A baghouse worker would likely be dressed in anti-contamination clothing. However, because of the prevalence of dust in the general refinery environment it is still reasonable to include the secondary agestion exposure pathway (inadvertent ingestion of surface contamination).
Handling EAF Dust at the Refinery This work-related scenario involves a refinery worker handling EAF dust at a refinery in preparation for shipment. Most EAF refineries do not process their dust before shipping, so this scenario assumes that there is no preparation of the dust for transport to a treatment and disposal facility or fertilizer manufacturer. The bulk dust is loaded directly from its storage container into a shipping container (e.g., an enclosed truck trailer) via a handling chute. The truck driver and the worker who disconnects the chute and caps the transportation container would be the only individuals in close pmximity to the dust or the truck for a significant amount of time. This scenario addresses the potential exposure of the refinery worker; the potential dose to the truck driver is covered in another scenario. This scenario involves a worker that is located on tcp of the container while the dust is being loaoed via a'i overhead chute or conveyor belt. Exposure to individuals other than the worker handling the chute are also possible. However, those people would not be in close proximity to the truck for more than a very short time, and any amount of dust that escaped the truck container would be small and would disperse before reaching any nearby occupied areas. The scenario does not include public exposures, because the dust is essentially contained at all times.
Exposure pathways:
External: The worker would be exposed to penetrating radiation from the volume of dust inside the container.
Inhalation: This scenario assumes that while dust is being loaded into a truck container, a fraction escapes and could be inhaled by the worker.
Secondaryingestion: The EAF dust that is resuspended during the loading of dust into the shipping container can be deposited as surface contamination, causing inadvertent ingestion of EAF dust from contaminated hands and food.
Handling Refined Metal Product at the Refinery This work-related scenario covers a variety of specific jobs involving working close to refined metal slabs, rods, sheets, and other forms at a refinery or mill. Even though just handling the i metal products will not generate airbome dust, other processing activities ongoing at the refinery l (melting, pouring molten steel, water-cooling steel, etc.) would cause metal dust to be !
resuspended in the air. Similar to the refinery baghouse operations scenario, EAF refined metal product is the case analyzed and bounds the exposure at BOF refineries. i Draft NUREG-1640, Vol.1 4-38 O
t j i
S:ction 4 Recycle and Disposal of Steel l
Exposure pathways:
V External: The worker would be exposed to penetrating radiation from the metal forms.
. Inhalation: Inhalation of the resuspended metal dust from the various processing activities i i mentioned is possible.
Secondaryingestion: Suspended dust from other refinery operations could be deposited as j surface contamination, causing inadvenent ingestion from contaminated hands and food.
Handling BOF Refined Metal During Product Manufacture !
This work-related scenario involves proximity to metal sheets in a metal-shop or factory and activities such as bending, cutting, or shaping metal, which could result in resuspended metal particles. Metal products from BOF refineries represent the analyzed scenario because EAF metal products are typically items such as rebar and metal tractor cleats, and they do not undergo further manufacturing.
1 i
Exposure pathway: !
l External: The worker would be exposed to penetrating radiation from the metal forms. j Inhalation: Manufacturing activities would generate airborne metal particles. l Secondaryingestion: Material deposited as surface contamination could be inadvertently ingested from contaminated hands and food.
Handling EAF Refined Metal Product During Distribution This work-related scenario involves activities for distributing products made of EAF metal for final use. Examples of potentially affected workers include delivery truck drivers, warehouse workers, and shipping and receiving personnel. Metal items include such things as industrial items, construction supplies, and general consumer products. Electric arc furnace metal product is the case analyzed for this scenario for two reasons: 1) a larger percentage of the charge at an .
I EAF refinery would be scrap metal and 2) there is a shorter amount of time from production of the metal to distribution for the EAF than the BOF (therefore less radioactive decay).
Exposure pathways: 1 l
External: Because distribution workers would not be in an environment where activities would result in airbome metal dust, they would only be exposed to penetrating radiation from the l finished metal products.
I t
I 4-39 Draft NUREG-1640, Vol.1 i
i Recycle and Disposal of Steel Section 4 4.6.2.2 Processing Scenarios Refinery byproducts (dust and slag) must be processed before use or disposal, providing opportunity for worker exposure to radioactivity. For this study, a variety of work-related O1 conditions and practices were analyzed to identify the most likely exposure scenarios. This !
included investigating the details of work-related settings to develop accurate and representative l scenarios and to assign reasonable values (and ranges) to exposure parameters. During scenario {
development, details were re-examined to ensure that appropriate scenarios were identified and completely described.
Processing activities involve potential exposure to all radionuclides present in refinery 4 byproducts by all three exposure pathways. Most processing activities involve worker proximity I to large masses of volumetrically contaminated refinery byproduct and moving it by a front-end loader. The driver operating a front-end loader in close proximity to a large pile of material is the individual evaluated. Other possible exposures (e.g., to other workers in the facility) would be small. This scenario category includes two specific scenarios:
- Processing EAF dust for disposal
- Processing slag for use as aggregate or as roadbed Processing EAF Dust for Disposal This work-related scenario addresses a worker at a processing facility moving dust with a front-end loader or working near a pile of EAF dust.
Exposure pathways:
External: A worker in proximity to large masses of contaminated EAF dust would be exposed to penetrating radiation from the volume source.
Inhalation: While the EAF dust is being moved by the front-end loader, a fraction ofit could be suspended into the air, where it could be inhaled by the worker.
Secondaryingestion: The material that is suspended can be deposited as surface contamination, enabling secondary ingestion of radioactive material from contaminated hands and food.
Processing Slag for Use as Aggregate or as Roadbed This work-related scenario addresses a worker at a processing facility moving slag with a front-end loader or working near a slagpile. The same type of activities that occur at a facility processing EAF dust would occur here. Slag from an EAF refinery is the case analyzed, because a larger percentage of an EAF charge is comprised of scrap metal, therdore, potentially resulting in a higher concentration of radionuclides in slag.
I Draft NUREG-1640, Vol.1 4-40 O'
l l
r Section 4 Recycle and Disposal of Steel Exposure Pathways:
External: Exposure to penetrating radiation from the material volume source (the slag pile).
Inhalation: A fraction of the slag could be suspended into the air, where it could be inhaled by the worker.
l Secondaryingestion: Suspended material could be deposited as surface contamination, allowing j inadvertent secondary ingestion of radioactive material from contaminated hands and food.
4.6.2.3 Storage Scenarios ;
1 Prior to use or disposal, slag is stored in large piles at the refinery and EAF dust in a storage silo. l This category evaluates one work-related exposure scenario (any work-related exposures from a I slap pile would be bounded by the slag handling scenario).
Storage of EAF Dust at Refinery This scenario evalcates rotential exposure to a worker at a refinery performing activities near an i EAF dust silo. This scenario assumes that a worker would be located near the silo where the EAF dust is stored, for a certain amount of time each day. Exposure to EAF dust is being analyzed intead of BOF dust because the concentration of radionuclides is higher in EAF dust, due to less mixing with non-contaminated material in each fumace charge.
N Exposure pathway:
External: Because EAF baghouse dust is typically contained within a silo, exposure to penetrating radiation from the material volume source (the silo) is the only pathway explored.
4.6.2.4 Product Use Scenarios-Workers The product-use category includes an extremely large number of possible worker exposure situations. Because this cater ry includes the use of products manufactured from recycled scrap metal as well as refinery byproducts, it represents the most diverse category of potential exposure scenarios-including both work-related and public exposures. The size and diversity of potential exposure situations makes it difficult to identify, organize, screen, and evaluate all possible scenarios.
This analysis does not evaluate the wide variety of possible worker product use scenarios. These exposure scenarios would be similar to the many potential non-worker product use scenarios, and are, therefore, implicitly addressed in the non-worker scenarios described in Section 4.6.3.3.
Refinery slag is considered a product of the refining process and is used in the single worker product-use scenario: road construction activities using refinery slag.
O b 4-41 Draft NUREG-1640, Vol. I
I l
Recycle and Disposal of Steil Section 4 Road Construction Activities Using Refinery Slag This work-related product-use scenario involves the use of refinery slag as construction material for a roadbed. It evaluates the potential exposures associated with activities necessary for handling and laying the slag as road construction material.
In this scenario, the slag is transported in a large dump truck to the construction site, where it is dumped onto the roadbed and spread evenly on the road. The majority of work-related exposure would occur as a result of being on the slag, to level it, after it is dumped on the roadbed.
Therefore, the worker using the leveling equipment on the slag is the individual evaluated. The exposure to the worker loading the dump truck from the slag pile is bounded by the handling slag at the refinery scenario, and the exposure to the driver of the dump truck is bounded by the transport of slag scenario.
Exposure pathways:
Externah This scenario assumes that a worker is on the surface of the roadbed leveling the slag and would be exposed to penetrating radiation from the slag volume source.
Inhalation: While the slag is being dumped and leveled, a fraction ofit could be suspended into the air, making inhalation by the worker possible.
Secondaryingestion: Redeposited surface contamination can be inadvertently ingested on contaminated hands and food.
4.6.2.5 Transportation Scenarios One activity that occurs many times throughout the material flow for steel is transportation (see Figure 4.1). Scrap metal cleared from NRC licensed facilities must be transported from the nuclear facility to the refinery, and the refined metal product and refinery byproducts must be transported from the refinery or mill to manufacturers, processors, users, or disposal sites.
Although these can occur by either truck, rail, air, or barge, truck transportation is most mmmon.
Truck transportation also presents the highest potential dose to individuals because ofI sac exposure times and small distances from the source (truck) to the receptor (driver).
In general, those who handle packages directly are exposed to the highest dose rates, although these exposures are usually for relatively short periods of time. Bystanders and persons traveling or living along a travel route generally are subjected to lower dose rates. In most cases, exposures of persons along the transport route are for a relatively short duration, but the number of persons who can be exposed may become very large during a shipment of considerable distance. A worker (the truck driver) is analyzed for all transportation scenarios.
Draft NUREG 1640, Vol. I 4-42 O
Section 4 Recycle and Disposal of Steel The transportation scenarios analyzed for this report include:
\
- Transport of scrap metal Transport of slag
- Transport of untreated EAF dust Transport of refined metal product.
Exposures of the general public during transportation are addressed in Section 4.6.3.4.
Exposure pathways:
External: The only exposure pathway included in the evaluation of all transportation scenarios is the external exposure pathway for penetrating radiation from the truck load of material (e.g.,
scrap metal, slag, EAF dust).
Transport of Scrap Metal This scenario describes the transportation of scrap metal from the nuclear facility. As described )
in Section 4.2, the scrap metal can either be transported to a scrap dealer ifit is suitable for recycling, to the user ifit is suitable for direct reuse rather than recycling, or directly to a disposal facility ifit is not suitable for either recycling or direct reuse.
j Transport of Slag t/ This scenario describes the transportation of slag from the refinery to processors. The majority of refinery slag is transported by truck within a 50 km (80 mi) radius ofits source, the refinery.
Transport of Untreated EAF Dust This scenario describes the transportation of EAF dust from the refinery to manufacturers or processors (e.g., hazardous landfill or fertilizer manufacturer). As described in Section 4.2, EAF baghouse dust is transported to either a hazardous landfill for immobilization and disposal or to a fertilizer manufacturer for use as an additive. i i
Transport of Refined Metal Product This scenario describes the transportation of refined metal product from the refinery or mill to the manufacturers or distributors. Electric are furnace refined metal products are sent directly to j the distributors with no additional manufacturing required, while BOF refined metal products are j sent to manufacturers prior to distribution (see Section 4.2). Because EAF refineries typically l use more scrap metal in a furnace charge than BOF refineries, and, therefore, have greater potential radionuclide concentratiens in refined metal products, the case analyzed for this scenario is the transport of EAF refined metal products. 1 (O
l 4-43 Draft NUREG-1640, Vol. I l
l i
)
Recycle and Disposal of Steel Section 4 4.6.2.6 Disposal Activities Scenarios When scrap metal or refinery byproducts have reached the end of their usefulness, they are disposed ofin either a RCRA Subtitle C (hazardous) or D (sanitary) landfill. Material placed in a Subtitle C landfill is stabilized and, typically, placed in 55-gallon drums prior to disposal.
Material placed in a Subtitle D. sanitary landfill is not stabilized or placed in containers before disposal. Disposal of this material involves workers placing waste in the final location within the landfill unit, an activity that requires workers to spend time near the waste.
This category of scenarios evaluates the activities associated with the disposal of materials. The disposal activity scenarios include reasonable exposures to disposal facility workers. Some of the total potential exposure is likely to occur after disposal of cleared material, not during actual handling of the material (i.e., external exposure to disposed waste material).
Four work-related disposal activities scenarios were examined for this study. These scenarios address those workers involved with the disposal of the material.
Disposal of BOF dust in a sanitary landfill Disposal of refinery slag in a sanitary landfill Disposal of scrap metal in a sanitary landfill
- Disposal of EAF dust in a hazardous waste landfill.
No exposures of the general public would occur under any of the work-related disposal scenarios presented here.
Disposal of BOF Dust in a Sanitary Landfill This work-related exposure scenario describes a worker disposing of BOF dust in a sanitary landfill. Such activities can include a worker moving the BOF dust with a front-end loader from a pile or tmck to the landfill, or a worker on a piece of machinery, such as a bulldozer, .
compacting the material in the landfill. The BOF dust is assumed to be in a form similar to soil, l with suspension of the material for inhalation and inadvertent ingestion by the worker. This l scenario assumes that BOF dust is disposed ofin a sanitary landfill directly after production at the refinery. Only the worker involved with the actual disposal activities is addressed.
Exposure pathways:
l External: Exposure to penetrating radiation from the BOF dust on the ground.
i Inhalation: Exposure to suspended BOF dust. -
l l
Secondary ingestion: Inadvertent ingestion of surface contamination.
l Draft NUREG-1640, Vol.1 4-44 O
Section 4 Recycle and Disposal of Steel (N Disposal of Refinery Slag in a Sanitary Landfill j Q This work-related exposure scenario describes a worker disposing of slag in a sanitary landfill. );
Such activities can include a worker moving the slag with a front-end loader from a pile or truck to the landfill or a worker on a piece of machinery, such as a bulldozer, compacting the material j in the landfill. The slag is assumed to be in a form similar to soil, with suspension of the j material for inhalation and inadvertent ingestion by the worker. This scenario assumes that slag {
is disposed ofin a sanitary landfill directly after production at the refinery. Only the worker l involved with the actual disposal activities is addressed. !
1 Exposure pathways External: Exposure to penetrating radiation from the slag in the ground.
1 Inhalation: Exposure to suspended slag. ;
1 Secondaryingestion: Inadvertent ingestion of surface contamination.
Disposal of Scrap Metalin a Sanitary Landfill This work-related exposure scenario describes a worker disposing of NRC licensed facility scrap l metal in a sanitary landfill. Only the worker involved with the actual disposal activities is addressed. Disposal activities can include a worker at the landfill handling the metal manually or i using machinery. Activities can also include a worker on a piece of machinery, such as a g
Vj bulldozer, compacting the scrap metal.
i' l
Because no mechanical cutting or shredding of cleared scrap metal is assumed to occur prior to !
disposal, it is reasonable to assume that there would be no appreciable suspension of i contamination, and therefore, no inhalation exposure to resuspended material. Likewise, there j would be no mechanism that would result in appreciable amounts of contamination for inadvertent ingestion. Therefore, the only exposure pathway that is relevant is the extemal exposure to penetrating radiation from the volume source. This scenario assumes that scrap metal is disposed ofin a sanitary landfill directly from the nuclear facility. i Exposure pathway:
Erternal: Exposure to penetrating radiation from the scrap metal in the ground.
Disposal of EAF Dust in a Hazardous Waste Landfill This work-related exposure scenario describes a worker disposing of EAF baghouse dust immobilized in 55-gallon drums in a hazardous landfill. Handling includes moving the 55-gallon drums with a fork lift, moving them from a vehicle to a storage facility, or placing them into the landfill unit. (NOTE: Processing the dust, immobilizing it, and placing it in 55-gallon drums is covered in Section 4.6.2.2). Because the EAF dust is immobilized in the 55-gallon drums, it is
[]/ reasonable to assume that there is no suspension of contamination and, therefore, no exposure 4-45 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Srction 4 due to inhalation of the resuspended material or inadvertent ingestion of surface contamination.
Therefore, the only exposure pathway that is relevant is the external exposure to penetrating radiation from the volume source. Only the worker involved with the actual disposal activities is addressed. Exposures could also occur after initially handling the drums. These exposures are also included. I Exposure pathway: j External: Exposure to penetrating radiation from the 55-gallon drums containing immobilized EAF dust.
4.6.3 Description of Non-worker Scenarios The exposure scenario categories that include non-worker exposure are:
. atmospheric releases a storage
- product use a transportation
. resident on closed landfill.
4.6.3.1 Refinery Atmospheric Releases When scrap metal is processed at a refinery, atmospheric effluents released from the stack potentially expose people living nearby to radioactivity contained in the release. A representative scenario was evaluated for this category:
Atmospheric Release During Refining l This public exposure scenario takes place near a refinery that is processing scrap metal from a l nuclear facility. During the refining process, atmospheric effluents are released from the stack.
The scenario assumes the exposed person lives in the area surrounding the refinery year round and has a home garden.
This scenario includes the exposure pathways listed below and illustrated in Figure 4.3.
Draft NUREG-1640, Vol.1 4-46 O
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l Recycle and Disposal of Steel Section 4 Exposure Pathways:
I External: Exposure to penetrating radiation from volume sources while indoors and/or outdoors. {
1 Inhalation: Exposure to the passing plume while indoors and outdoors, to suspended soil while indoors and outdoors, and to suspended surface sources from soil tracked indoors.
Ingestion offood and soll: Ingestion of soil (secondary) from plant products grown in contaminated soil and soil tracked indoors (inadvertent).
This set of exposure pathways, along with the selection of reasonable parameter values, provides a comprehensive analysis for this scenario.
i Other exposure pathways are possible, but werejudged to have very small contributions in I comparison to the ones selected. For instance, ingestion of drinking water from a contaminated l I
surface water source in the vicinity of the refinery would be very small unless very large amounts of radioactivity were released. Similarly, a potential dose from ingestion of drinking water from a contaminated ground-water source would be insignificant unless the atmospheric deposition source was very large and the subsequent transport to groundwater was rapid and unretarded.
The material that is released from a refinery stack is in two forms; particulates and off-gases.
The off-gases are either completely volatilized or are in the form of particulates too small to be captured in the air pollution control system at the refinery. Besides these off-gases, a small fraction of the larger particulates that are produced are also released into the atmosphere. This is because the baghouse filters that make up the air pollution control system are not 100% efficient.
On average, these filters are about 99% efficient (see Sections 4.2 and 4.3).
Refinery emissions are the principal airborne effluents of concern during recycled steel processing. Other effluents could be postulated, such as fugitive atmospheric releases from scrap handling, however, these effluents are considered insignificant due to the small probability and small magnitude of any release.
Listed below are assumptions for the specific exposure pathways.
External: People that live near the refinery would spend their time indoors, outdoors, and offsite.
The time spent offsite is the fraction of the year that no external exposure occurs. Therefore, the annual effective dose equivalent (EDE) for the external exposure pathway results from outdoor activities and indoor activities onsite. The radionuclide concentration on the soil as a result of deposition from the plume is used as the basis for calculating the external exposure.
Ingestion offood andsoil: In general, an individual is assumed to live at a residence that has soil contaminated via atmospheric deposition. Ingestion pathways that are included are ingestion of plant products grown at the receptor location and secondary (inadvertent) ingestion of surface soil at the receptor location. Since the ingestion dose is based on the air concentration at the Draft NUREG-1640, Vol. I 4-48 O'l
I i
Section 4 Recycle and Disposal of Steel e specified receptor location, the calculated intake of radioactivity is based on concentrations of radionuclides in plant products grown at the same location.
1 The following assumptions were made for the ingestion pathway: <
The concentration of radionuclides in edible parts of the plant at the end of the first
- growing period is used as the harvest concentration. Multiple harvesting of plant crops is not included.
The concentration of C-14 and H-3 in the edible parts of the plant due to atmospheric release was calculated separately using different equations.
The resident consumes soil, leafy vegetables, and other vegetables grown on the .
contaminated soil. !
=
The harvested crops, v, for human consumption (i.e., leafy vegetables and other vegetables) are retained during a hold-up period before human consumption.
The consumption period by an individual for plant food crops is 1 year. Radioactive ;
decay during the consumption period is accounted for in the intake calculation.
l Instantaneous equilibrium occurs between the radionuclide concentration in the soil and in the concentration in the plants. !
4.6.3.2 Storage Scenarios j Prior to use or disposal, slag is accumulated and stored in large piles at the refinery and EAF dust in a storage silo. This category evaluates one exposure scenario, storage of slag at refinery. I Storage of Slag at Refinery This non-worker scenario takes place near a refinery that stores slag outside and does not include any work-related exposures associated with handling the slag. This scenario does not include
, potential exposures associated with direct contact with the slag by the public (i.e., external, j l exposure inhalation, or inadvertent ingestion). These exposure pathways are addressed in the l work-related scenario which describes the worker near a slag pile (Section 4.6.2.1). Any public l exposure that would occur near the pile, such as external or inhalation, would be very small ;
because of the likely distance between the piles and any non-workers. Therefore, the only r pathway analyzed in this scenario is the ingestion of drinking water from a groundwater source. I I
! The analysis models the transport of radionuclides from the slag pile to the groundwater and
'~
subsequent intake by a member of the public. The total effective dose equivalent (TEDE) due to j the ingestion of drinking water is calculated for a period of 1 year.
l O 4-49 Draft NUREG-1640, Vol. I l
Recycla and Disposal of Steel Section 4
' xposure Pathway.
Ingestion ofdrinking water: A member of the public would ingest contaminated drinking water from a well near a refinery.
Once the slag is placed outside on the unprotected ground there is a potential to contaminate groundwater in either the saturated or unsaturated zones. The primary mechanisms controlling potential groundwater contamination include infiltration and leaching, transport through the unsaturated zone, and transport through the saturated zone. Many additional characteristics of the site influence these mechanisms, including precipitation rates, the land's surface properties, soil properties, the chemical nature of the radioactive contamination, spatial distributions of the I contamination, and advection/ retardation in the aquifer. )
)
For this scenario, the method used to estimate the concentration of radionuclides in a groundwater aquifer is a simple leach-rate model accounting for total water use. Leach rates are dependent on the chemical properties of the radionuclides and soil / slag and the rate oflocal water ;
movement. For the water-use model used, it was assumed that radionuclides would be transferred to the groundwater because of contact with infiltrating water (i.e., as a function of the solubility of the material in water with no retardation in soils). To account for potential saturated ,
and unsaturated conditions, a three-box compartmental model, similar to that used in l NUREG/CR-5512 (Kennedy and Strenge 1992), is used to estimate the transfer of radioactivity )
from the surface to the groundwater aquifer over time. Figure 4.4 illustrates the three-box !
compartmental model. i l
The basic drinking water scenario from NUREG/CR-5512 is used for this scenario (Kennedy and I
+ Domestic Use f Infiltration -
i Ground-Water i Thickness =H1 5 $ 2 !
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Ie Section 4. Recycle and Disposal of Stzel Strenge 1992). Assumptions for the drinking water model are listed below (box numbers refer to L Figure 4.4):
=
l Initial radioactivity is contained within box 1 (slag pile) and is assumed to be constant l throughout the year.
. Box 2 (unsaturated zone) and box 3 (aquifer) are initially free of contamination.
The unsaturated zone refers to the distance between the bottom of the slag pile to the top of the aquifer. For simplicity, the soil in this zone is treated as being homogeneous.
l Vertical, saturated, hydraulic conductivity is greater than the infiltration rate; water will -
move vertically downward at least as fast as the infiltration rate.
- Infiltration volume is the product of the infiltration rate and the area ofland l contaminated.
No retardation in box 3 (aquifer).
. Activity in box 3 (aquifer) is diluted by the total volume of water in the aquifer Radionuclide concentrations in all parts of box 3 (aquifer) are the same. Radionuclides s entering box 3 (aquifer) are immediately and uniformly mixed with the total volume of water in the aquifer.
. Water is removed from the aquifer at a constant rate during the year to meet the needs of irrigation and domestic water uses. The volume of water removed is immediately replaced with an equal volume of uncontaminated water.
l
- The volume of water used for domestic purposes is sufficient for ten people.
l * . Radioactivity not removed during a year remains in the aquifer and contributes to the L - initial radioactivity concentration for the next annual period.
. . Water infiltration rate is a fraction of the total water application rate, which is equal to the annual precipitation rate.
L = . Evaporative losses remove only water from the system (i.e., surface soil); radioactivity is l not lost by evaporation.
l l Steel slag is a very basic substance, and any water that leaches through a large pile of slag would become "hard" through the leaching of oxides of calcium and magnesium. Therefore, it is likely that in this scenario, an aquifer underlying a large slag pile would contain high concentrations of Q'
i L
4-5) Draft NUREG-1640, Vol.1 L
f l
Recycle and Disposal of Steel Section 4 l dissolved solids. In order to incorporate the probable high dissolved solids content of the aquifer in this scenario, the total dissolved solids (TDS) in the aquifer were calculated over a period of time, and when a TDS level of 10,000 mg/L was reached, the aquifer was no longer considered drinkable. This TDS level is part of the EPA definition of an " underground source of drinking water" (e.g.,40CFR146) and is considered a reasonable natural limit on potability of drinking water, even without regulatory oversight.
4.6.3.3 Product Use Scenarios-Non-workers The product-use category includes an extremely large number of possible exposure situations.
Because this category includes the use of consumer products manufactured from recycled scrap metal, as well as refinery byproducts, it represents the most diverse category of potential exposure scenarios-including both work-related and public exposures. The size and diversity of potential exposure situations makes it difficult to identify, organize, screen, and evaluate all possible scenarios. In line with the goa. set for this study (the scenarios are required to be comprehensive, appropriate, and practical) exposure scenarios were represented generically instead of modeling a limited group of specific scenarios. The generic representations describe groups of similar exposure situations (e.g., individuals close to a large mass of metal or a small mass of metal close to tissue) rather than specific scenarios (e.g., person wearing a belt buckle or using a frying pan). The sub-category of" individuals close to a large mass of metal," for example, represents exposure situations such as individuals using office equipment (a desk) or large consumer products (a refrigerator) made from recycled steel.
The product-use exposure scenarios analyzed for this report include:
. In proximity oflarge. metal mass
= In proximity of small steel mass
- Small steel mass close to body
. Inside an automobile a Inside a steel-framed structure
- Use of slag as aggregate in basement construction
. Use of slag in a roadbed.
In Proximity to Large Metal Mass Following clearance from a licensee, scrap metal would enter the scrap metal market, where it could be melted and made into sheets or large, more massive pieces of steel stock. These in turn can be manufactured into large metal items used by workers, consumers, or other members of the general public. These items could be used in homes, offices, warehouses, and other industrial settings.
This scenario description is intended to be generic, in the sense that no specific situation is described and is representative of any of the settings listed above. Among the numerous examples of objects this scenario is intended to cover are large home appliances (such as Draft ' TUREG 1640, Vol. I 4-52 e
1 Section 4 Recycle and Disposal of Steel
- refrigerators and washing machines), office furnishings (such as large filing cabinets and metal
- ]\ desks), and large industrial machines. ' An individual near such an object would be subject to extemal radiation from radionuclides contained in th.e metal. The geometry of the object can be represented generically by viewing it as an individual near a "large metal mass." Other settings where this geometry is applicable include less frequented areas, such as near highway bridge supports, and certain work-related settings, such as near scaffolding or other large items.
Items falling into the category of "large objects" could be the products of either a BOF refinery I
- (e.g., appliance, large filing cabinets) or EAF refineries (e.g., large structures like bridge supports or scaffolding), based on the type of products from each refinery type (Section 4.2). )
~ Activities conducted as part of this scenario could include short duration activities (e.g.,
occasional use ofindustrial items, such as scaffc! ding), medium duration (e.g., office work), and ,
long duration (e.g., residential). The case analyzed was of an individual in a residential setting '
where a BOF product is used, because it is more likely that BOF products would result in the residential exposures described in this scenario.
Exposure pathway:
Externah The only exposure pathway included in the scenario evaluation is the external exposure pathway for penetrating radiation from the large object.
In Proximity to Small Steel Mass This scenario addresses activities that take place in the vicinity of a small object that is constructed of metal made from recycled scrap metal. The scenario description is generic, in the sense that no specific situation is described. Rather, this scenario covers use of numerous small ,
objects composed of metal from either a BOF refinery (e.g., small appliances such as a toaster) or EAF refineries (e.g., hand tools). Items could be used in homes, offices, warehouses, and other industrial settings. An individual near such an object would be subject to external radiation from radionuclides contained in the metal.' The geometry of the object can be generically represented by categorizing it as an individual near a small steel mass.
Activities conducted as part of this scenario could include short duration activities (e.g.,
i occasional use ofindustrial items such as small tools), medium duration (e.g., an office worker),
l and long duration (e.g., residential). The case analyzed is of an individual in a residential setting where a BOF product is used. .
Exposure pathway:
Externah The only exposure pathway included in the scenario evaluation is the external l- exposure pathway for penetrating radiation from the small object. Other exposure pathways.
l theoretically possible-such as inhalation of contaminated material from degraded metal-are not likely to be significant, compared to doses from external exposure.
O
\j 4 53 Draft NUREG-1640, Vol.1
1 Recycle and Disposal of Steel Section 4 Small Steel Mass Close to Body This public-use scenario is similar to the scenario Proximity to Small Steel Mass, above, in that it addresses activities that take place close to a small object that is constructed of metal made from recycled scrap metal.' The scenario description is generic and covers the use of numerous small items, such as tools or belt buckles, made of metal from an EAF refinery. An individual very i near such an object would be subject to external radiation from radionuclides contained in the metal. The geometry can be represented generically by a small metal object essentially on an individual's body.
Exposure Pathway:
External: The only exposure pathway included in the scenario evaluation is the extemal exposure pathway for penetrating radiation from the small object.
Inside an Automobile Following clearance from an NRC licensed facility, cleared scrap metal would enter the scrap metal market, where it could be melted and made into components for a vehicle. This is a likely occurrence, because approximately 70% of a typical U.S. automobile is made from steel and iron, and many of the steel components (e.g., undercarriage, engine block, axle, springs, and drive shaft) are made from recycled steel (SRI 1995). An individual inside such a vehicle would be subject to extemal radiation from radionuclides contained in the metal components. The geometry can be represented generically by a plane (the undercarriage, drive shaft, axle, etc.) and a block of metal (engine block).
The exposed group in this scenario consists of people who drive or ride in an automobile a significant part of each day (more than one hour). The scenario may be work-related (i.e., a fleet driver) or non-work-related (e.g., a commuter).
Exposure pathway:
External: The only exposure pathway included in the scenario evaluation is the external exposure pathway for penetrating radiation from the steel vehicle components. Other exposure pathways theoretically possible-such as inhalation of contaminated material from degraded metal-are not likely to be significant, compared to doses fro'm external exposure, because the residual radioactivity would be distributed throughout the volume of the recycled steel and hence would not be easily mobilized.
Although the metal could come from either an EAF or BOF, it is more likely that the types of structural components involved in the scenario are products of EAF refineries. Therefore, this scenario assumes EAF steel was used.
Draft NUREG-1640, Vol.1 4-54 O
Section 4 Recycle and Disposal of Steel 7 inside a Steel-Framed Structure
.t Following clearance from an N,RC licensed facility, cleared scrap metal would enter the scrap metal market, where it could be melted and made into steel-framing components. This is an increasingly likely occurrence, as the steel-framing industry uses recycled steel components, and this U.S. residential industry is growing. The American I~ onr and Steel Institute estimates that the number of full steel home starts in the U.S. has doubled from 40,000 in 1994 to 95,000 in 1997 and is projected to reach 325,000 by the year 2000 (AISI 1998).
An individual inside a steel-framed building would be subject to external radiation from radionuclides contained in the metal structural components. The geometry can be represented generically by an individd weide a cage.
The exposed group in this scenario consists of people who spend time inside a building containing structural members made of recycled scrap steel. They could be in a work-related setting (e.g., an office building) or a residential setting (a home). Activities conducted as part of this scenario could include short duration activities (occasional entry into a warehouse), medium duration (office work), and long duration (residential). All of these were considered in determining the exposure duration time for this scenario, however, the office and residential settings were emphasized due to the longer times inside the building.
Although the metal could come from either an EAF or BOF, it is likely that the types of structural components involved in the scenario are products of EAF refineries. Therefore, this b
O scenario assumes EAF steel was used.
Exposure Pathway:
Externah The only exposure pathway included in the scenario evaluation is the external exposure pathway for penetrating radiation from the steel frame material (studs and joists).
Other exposure pathways theoretically possible-such as inhalation of contaminated material from degraded metal-are not likely to be significant, compared to doses from extemal exposure, because the residual radioactivity would be distributed throughout the volume of the recycled steel and, hence, would not be easily mobilized.
Use of Slag as Aggregate in Basement Construction This public residential scenario evaluates exposure from slag used as aggregate in concrete. Slag produced as a byproduct of refining can be used for construction of basements in homes, although this is a limited practice. Because ofits unsuitability, steel slag would not constitute more than 3% of any concrete mixture. An individual living in a home with a basement built of concrete with steel slag would be subject to extemal radiation from radionuclides contained in the slag.
~
\
i 4-55 Draft NUREG-1640, Vol.1
Recycle and Disposal ef Steel Secdon 4 The individual evaluated in this scenario is a member of the public whose basement is constructed with concrete containing refinery slag, and who spends the maximum defined period inside the home.
Exposure Pathway:
External: The only exposure pathway included in the scenario evaluation is the external
. exposure pathway for penetrating radiation from the slag.
Use of Slag in a Roadbed Refinery slag can be used n an aggregate in a roadbed. For this scenario, it is assumed that slag is used as a base and asphalt or concrete is placed over it. Since the slag is either contained I within or under a solid mass, no resuspension ofit can occur under normal conditions. It is !
recognized that slag is sometimes used as the entire roadway and is not contained in a solid mass.
The potential dose from this type of use is bounded by the evaluation of the work-related scenario addressed in Section 4.6.2, Road Construction Activities Using Refinery Slag.
Exposure would differ by type of use. The average driver may only be on the roadway a short time each day, whereas a truck drivercan spend a ful! work day on the road. However, the length of time that a person is potentially exposed is balanced by proximity and shielding. The truck driver is much higher off the ground and is more heavily shielded than is the average driver in a car. This scenario analyzes the average person in a car.
Exposure Pathway:
Erternal: Because there is no possibility for the suspension of the slag in this scenario, only extemal exposure to penetrating radiation from the volume source (the slag in the roadbed) is analyzed.
4.6.3.4 Transportation One non-worker receptor was initially analyzed for all transportation scenarios, a maximally exposed individual aMng the transportation route. This person is either caught in traffic next to the truck or is driving next to the truck for a distance. The dose factors for this situation were found to be i significant and are, therefore, not included in the final tabulation of dose factors.
4.6.3.5 Resider.t on Closed Landfill This category of public exposure scenarios involves a resident on the site of a RCRA Subtitle C or D landfill unit after the completion of the post-closure monitoring period. These scenarios are i
of a different nature than the other scenarios analyzed, because they describe unlikely situations potentially occurring many years in the future. Therefore, the dose factors calculated for the four landfill-resident scenarios were not used in the critical group determination, but were analyzed l Draft NUREG-1640, Vol. I 4-56 O
m z Senion 4 Recycle and Disposal of Steel
- l. for completeness. The scenarios are described here and elsewhere in this section, and a summary of the highest landfill-resident dose factors is included in Appendix J.
O Section 4.6.2 discussed exposure of workers involved with disposing various types of material in ;
l a either a RCRA Subtitle C or D landfill. This section introduces the scenarios describing I i_ potential exposures to the general public after closure of such a landfill. The four scenarios !
examined for this study are:
l i . Resident on closed landfill after disposal of BOF dust
. Resident on closed landfill after disposal of refinery slag
- Resident on closed landfill after disposal of scrap metal
. Resident on closed landfill after disposal of EAF dust i
These scenarios are very similar to each other, with the disposed material representing the most significant difference. No scenarios involving more than one potentially contaminated byproduct of recycle have been evaluated, however, doses from more than one of the scenarios listed above i could be added if appropriate.
This resident scenario category involves a person occupying a house with a basement and ;
maintains a vegetable garden on the site of a closed landfill that contains material derived from J l- cleared scrap. steel. The exposure pathways modeled are listed and illustrated in Figure 4.5. The modeling approach and assumptions that each of the scenarios within this category have in common are presented below. ,
1 i -
Exposure Pathways: Specific exposure pathways included in the evaluation of resident scenarios are listed below. General and exposure-specific assumptions for the scenarios are discussed following this listing.
External: The only exposure pathway consists of penetrating radiation from volume soil sources while indoors and/or outdoors.
Inhalation: The inhalation pathway includes exposure to suspended soil while indoors and/or outdoors and to suspended surface sources of soil tracked indoors.
l l Ingestion offood and soll: Ingestion exposure includes soil (secondary ingestion) and soil tracked indoors (inadvertent ingestion), plant products grown in contaminated soil, soil contaminated by irrigation (direct and inadvertent), and plant products irrigated with contaminated ground water only.
I Ingestion ofdrinking water: This pathway is limited to ingestion of drinking water from a ground water source.
l k
4-57 Draft NUREG-1640, Vol. I l
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Section 4 ' Recycle and Disposal of Steel i~ l yg Because these residential scenarios are not based on worst case occurrences, several exposure i j pathways were not analyzed. For example, while air submersion may be an important pathway L\ to consider when evaluating the potential consequences of airbome releases from some facilities, numerous studies of residual contamination in soil left after decommissioning a nuclear facility have concluded that extemal doses from air submersion are trivial compared with extemal doses l from surface or volume sources (Schneider and Jenkins 1977; Smith et al.1978; Oak et al.1980).
Since these residential scenarios are similar to residual contamination in soil, left after l decommissioning a nuclear facility, air submersion doses are considered insignificant and are not . ;
l: evaluated.
Similarly, internal exposures from puncture wounds or from dermal absorptior 'nay be important i when evaluating sources of exposure to workers in licensed nuclear facilities. But most dose :
assessments using these pathways are retrospective (after-the-fact) and rely on bioassay results to help establish the magnitude ofinternal deposition that occurred for specific situations. The frequency of occurrence of puncture wounds, although unpredictable, is assumed to be low.
Dermal absorption may be important for only a few radionuclides, most notably H-3. To help account for dermal absorption of H-3, the International Commission on Radiological Protection (ICRP) increased the inhalation conversion by 50% (ICRP 1978). The dose that could result from dermal absorption is assumed to be low compared with inhalation and ingestion doses.
Thus, internal doses from puncture wounds and dermal absorption are not included in this scenario.
Finally, some ingestion pathways often included in subsistence farmer scenarios have been 7
(v omitted. Maintenance of a dairy cow, a cattle herd, a wheat field, or a fish pond were considered too unlikely to be appropriate for this exposed group. Therefore the milk, meat, grain, and fish -
ingestion pathways were not included in this scenario. Ingestion rates for home grown vegetables were chosen to represent a typical family garden rather than a subsistence farmer.
Six general assumptions for the residential scenarios are listed below. Assumptions specific to a particular exposure pathway are discussed following this listing of general assumptions.
. Waste is placed in the landfill in the middle ofits lifetime,15 years before closure of a hazardous landfill and 20 years before closure of a sanitary landfill.
. By a non-specific and unidentified means, the radionuclides in the waste are dispersed evenly throughout the soil to a depth equal to that of the original landfill. The time that
~ leaching begins is different for each type oflandfill. Waste disposed ofin a sanitary landfill begins leaching immediately after emplacement; waste disposed ofin a hazardous landfill begins leaching at the end of the post-closure monitoring period. Similarly, it is assumed that the total activity in the waste is dispersed throughout the total volume of material (soil and waste) in the landfill. This assumption simplifies the calculation by not attempting to model the complex and uncertain waste-leaching process.
f, 4 59 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4
. Contamination in the soil decays normally and continues to leach until the time activity is determined.
. hrigation (watering with contaminated groundwater) contaminates crops, which are subsequently ingested by the resident. Recycling of radioactivity in irrigation water back to the groundwater is not included in order to simplify the models.
- A resident moves onto the landfill site after a post-closure monitoring period is concluded. The scenario TEDE is for a 1-year period.
. The scenario "begins" at the time leaching starts, although no resident moves onto the landfill until 50 to 150 years later.
Exposure Pathway-Specific Assumptions External: The soil radioactivity concentration at the time a resident is assumed to move onto the landfill site consists of the radioactivity remaining in the contaminated layer after haching and radioactive decay occurring during the post-closure monitoring period. l l
l Residents on the contaminated soil would spend their time indoors, outdoors, and offsite. The time spent offsite is the fraction of the year that no extemal exposure occurs. Therefore, the annual dose for the extemal exposure pathway results from outdoor activitier and indoors activities onsite. The radioactivity concentration in the soil, when the resident moves onto the landfill, is used as the basis for calculating the extemal exposure.
Inhalation: Similar to the extemal exposure pathway, the inhalation exposure pathway involves a person that spends their time indoors, outdoors, and offsite. However, for this exposure pathway, the outdoor exposure is separated into time spent on dusty activities (e.g., gardening) and time spent on non-dusty activities (e.g., sitting). Because the original contamination occurs as soil contamination, the inhalation dose only includes the suspension of contaminated soil from the ground. The resuspension of soil indoors has two sources; material blown into the house from outside and the suspension of soil that was tracked into the house.
Ingestion offood and soil: The landfill resident is assumed to consume plants grown in a home garden. This individual would also be exposed to secondary (inadvertent) ingestion of soil or house dust.
The ingestion exposure pathway is separated into two parts: non-irrigation and irrigation models. These two models can be used separately (e.g., growing plants in contaminated soil and irrigating with uncontaminated water or growing plants in clean soil offsite but irrigating with contaminated water), or they can be used together (e g., growing plants in the contaminated soil and irrigating with contaminated water). Effective dose equivalents are calculated for each model separately, and the total ingestion (non-irrigation plus irrigation) dose assumes both occur simultaneously.
Draft NUREG-1640, Vol.1 4-60
1 Section 4 Recycle and Disposal of Steel The following assumptions were made for the ingestion pathway dose modeling:
The soil radionuclide concentration at the beginning of the crop-growing period is considered to be the same as the soil radionuclide concentration at the time the resident moves onto the landfill, Co.
The concentration of radionuclides in edible parts of the plant at the end of the first growing period is used as the harvest concentration. Multiple harvesting of plant crops is not included.
- A resident consumes soil, and vegetables, grown on the contaminated soil.
Harvested vegetables for human consumption are held for a hold-up period before human consumption.
The consumption period by an individual for plant food crops is 1 year. Radioactive decay during the consumption period is accounted for in the intake calculation.
. Instantaneous equilibrium occurs between the radionuclide concentration in the soil and the concentration in the plants (for both human and animal consumption).
Irrigation vs. Non-irrigation Ingestion Pathways r The irrigation ingestion pathway is similar to the non-irrigation pathway, except that the total
(
N. dose results from the use of contaminated irrigation water to grow plants in a home garden 3 instead of from surface soil contamination. In the non-irrigation ingestion model, the only contamination available to be transferred to the plants is due to the initial soil radioactivity concentration after the post closure monitoring period. In contrast, the irrigation model is used to calculate the dose to a person who consumes plants and soil irrigated with contaminated water. l The evaluation of resident doses can be made with both irrigation and non-irrigation models or i just one model. For example, if an individual lives on contaminated soil and irrigates with contaminated water, use of both would be appropriate. Altemately, if the scenario involves an individu I who lives on non-contaminated soil and irrigates with contaminated water, the irrigation model alone would be appropriate. For the evaluation of resident doses, the two i models are assumed simultaneously.
To calculate the radionuclide concentration in foods grown with contaminated irrigation water and consumed by a person living on the contaminated area, the following additional assumptions have been made.
. The entire land surface area is irrigated and under cultivation.
. Radioactivity in the irrigation water is deposited in box 1 (surface layer).
4-61 Draft NUREG-1640, Vol. I
i f
Recyr.le and Disposal of Steel Section 4 Initial radionuclide concentration in the soil is zero and the concentration in plants and
. oil is due only to the contamination from the irrigation water.
Plants are contaminated frem the irrigation water through deposition directly onto plants, deposition onto the soil, and subsequent root uptake into the plant.
The concentration of radionuclides in irrigation water is constant over the year of irrigation (an average water concentration is used).
Material deposited on plant surfaces is removed at a constant weathering half-life.
1 Radionuclide concentrations in the soil from inigation water are immediately m 1 equilibrium with radionuclide concentrations in edible portions of the plants grown in the soil.
Ingestion ofdrinking water: Once the conta.nination from the waste is placed in the landfill, it has the potential to contaminate groundwater in either the saturated or unsaturated zones. The primary mechanisms controlling potential groundwater contamination include infiltration and leaching, transport through the unsaturated zone, and transport through the saturated zone. Many additional characteristics of the site influence these mechanisms, including precipitation rates, the land's surface properties, soil properties, the chemical nature of tl.e radioactive contamination, spatial distributions of the contamination, and advection\ retardation in the aquifer.
For the drinking-water pathway, the method used to estimate the concentration of radionuclides in a groundwater aquifer is a simple leach-rate model accounting for total water use. Leach rates are dependent on the chemical properties of the radionuclides and soil and the rate oflocal weer movement. For the water-use model used, it was assumed that radionuclides would be transferred to the groundwater because of contact with infiltrating water (i.e., as a function of the solubility of material in water with no retardation in soils). To account for potential saturated and unsaturated conditions, a three-box compartmental model, similar to that used in NUREG/CR-5512 (Ke:medy and Strenge 1992) is used to estimate the transfer of activity from the surface to the groundwater aquifer over time. Figure 4.6 illustrates the three-box compartmental model.
The basic drinking-water scenario from NUREG/CR-5512 w'as used instead of the residential drinking-water pathway. The basic drinking-water scenario does not include the recycling of contamination from the aquifer back to the surface. The pumping-ree constant for the residential J scenario was used.
Assumptions for the drinking-water model are listed below (box numbers refer to Figure 4.6):
- Initial radioactivity is contained within box 1 (surface layer).
- Box 2 (unsaturated zone) and box 3 (aquifer) are initially free of contamination.
Draft NUREG-1640, Vol.1 4-62 O
Section 4 Recycle and Disposal of Steel Precipitation / Evaporation Irrigation
+ Domestic Use k Infiltration .#
} Ground-Water Thickness =H I ,
3 Thickness =H 2 i -
2 . .: .
t: .. a ,'
SNfNfkhkN_ Box 3 Fignre 4.6 Three-box compartmental model for surface-to-groundwater transport for f resident on closed landfill scenario Vertically saturated hydraulic conductivity is greater than the infiltration rate. Water will move vertically downward at least as fast as the infiltration rate.
Infiltration volume is the product of the infiltration rate and the nea ofland contaminated.
No retardation in box 3 (aquifer).
Activity in box 3 (aquifer) is diluted by the total volume of water in the aquifer (including the volume of water in the surface water pond that is recharged from the aquifer).
Radionuclide concentrations in all parts of box 3 (aquifer) are the same. Radionuclides !
entering box 3 (aquifer) are immediately and uniformly mixed w; n the total volume of !
water in the aquifer.
Water is removed from the aquifer at a constant rate during in year to meet the needs of irrigation and domestic water uses. The voletme of water removed is immediately replaced with an equal volume of unconte . aated water.
The volume of water used for domestic purposes is sufficient for ten people.
4-63 Draft NUREG-1640, Vol. I l
w Recycle and Disposal of Steel Section 4
. Water is removed from the aquifer at a constant rate during the year ofinterest in the analysis.
- Radioactivity not removed during a year remains in the aquifer and centributes to the initial concentration for the next annual period.
. Water infiltration rate is a fraction of the total water application rate, which is the sum of the irrigation application rate and the annual precipitation rate.
. Evaporative losses remove only water from the system (i.e., surface soil and surface-water pond). Radioactivity is not lost by evaporation.
The initial activity present in box 1 is defined as the total activity present in box 1 when leachina, begins. Once teaching begins, the contamination is dispersed evenly throughout the soil to a depth equal to the original depth of the landfill. The total capacity of the landfill unit does not consist completely of cleared waste. Dai.ly cover material is intersperse 6 between the waste, as well as being placed over the entire landfill upon closure.
( Landfill Resident Scenario Descriptions The specific landfill resident scenarios are described below.
Resident on a Closed Landfill After Disposal of BOF Dust This public exposure scenario describes exposure to a resident on the site of a closed sanitary landfill after the disposal of BOF dust from the refinery. This residence begins after the post-closure monitoring period is completed and does not include any work-related exposures associated with operating the landfill. This scenario assumes that the BOF dust is immediately disposed ofin a sanitary landfill in the middle ofits lifetime,20 years before closure. The waste I is assumed to begin teaching immediately upon placement in the landfill. Because the BOF duct is able to physically mix throughout the soil, the radioactivity is assumed to be dispersed throughout the mass of waste, daily cover-soil (soil used to cover the waste on a daily basis) and final cover-soil. This scenario addresses the same exposure pathways that are addressed in the generic scenario: drinking water, external er.posure, inhalation exposure, and ingestion exposure.
1 Draft NUREG-1640, Vol. I 4-64 O
I l
Section 4 Recycle and Disposal of Steel l Resident on a Closed Landfill After Disposal of Refinery Slag ld This public exposure scenario describes a resident on the site of a closed sanitary landfill after the disposal of refinery slag. This scenario assumes that slag is disposed ofin a sanitary landfill directly from the refinery and allowed to immediately leach towards the groundwater. A resident then moves onto the closed landfill after the completion of the post-closure monitoring period. I Because the slag is able to physically mix throughout the soil, the activity is assumed to be dispersed throughout the mass of waste, daily cover-soil, and final cover-soil. ;
Resident on a Closed Landfill After Disposal of Scrap Metal This public exposure scenario describes a resident on the site of a closed sanitary landfill after the disposal of scrap metal from a nuclear facility (direct disposal ofcleared scrap). In order to calculate the radionuclide concentration in the surface layer after leaching occurs, the total mass of material in which the radi6 activity is dispersed must be determined. Because the scrap metal cannot physically mix throughout the soil, the activity is assumed to be dispersed throughout the daily cover soil and final cover soil only.
Radionuclides are modeled to begin leaching from the scrap immediately upon placement in the landfill. The radionuclides in the scrap metal leach to the unsaturated zone beneath the scrap as well as the cover soil surrounding the scrap metal. The radioactivity that is leached to the cover .
soil surrounding the scrap metal is then accumulated and not allowed to leach toward the groundwater. This is reasonable within the context of this scenario because the same leach-rate l= .
constant is used for the movement of radionuclides from the scrap metal to the unsaturated zone and the cover-soil. Therefore, twice the normal amount is allowed to leach from the scrap metal.
A resident moves onto the closed landfill after completion of the post closure monitoring period, 50-100 years after the scrap metal is placed in the landfill.
Resident on a Closed Landfill After Disposal of EAF Dust This public exposure scenario describes a resident on the site of a closed hazardous landfill after the disposal of EAF dust directly from the refinery. This scenario assumes that EAF dust is disposed ofin a hazardous landfill directly from the refinery. Because EAF dust is placed in 55-gallon drums for disposal, leaching does not begin immediately upon disposal. At the end of the post-closure monitoring period, the integrity of the drum is assumed to be lost and the EAF dust is dispersed throughout the soil. The total mass of material in which the radioactivity is mixed includes the_ waste, daily cover-soil, and final cover-soil. At this point, modeling the radionuclides leaching toward the groundwater begins. A resident is assumed to move onto the landfill auer the completion of the post-closure monitoring period,95-145 years after the EAF dust is placed in the Irndfill.
p G 4-65 Draft NUREG-1640, Vol,1
Recycle and Disposal of Steel Section 4 4.6.4 Environmental Media Concentrations Resulting from Environmental Transport 4.6.4.1 Atmospheric Releases (Source Term, Dispersion, Media Concentration)
Before the TEDE from atmospheric releases can be calculated, the source term and atmospheric dispersion term, must be calculated. ,
As stated previously, the emissions from a refinery consist of two parts, the off-gases and the particulates that escape the air pollution control system. The volumetric release rate of air from the refinery stack over the time period ofinterest is not a critical value, as long as it is relatively constant, and it is assumed that all activity is released. The average radioactivity release rate from the refinery stack is the important parameter. This is represented in Equation 4.15.
- 0, <'
(A+A,)
g r * '
4.15 Q=
RD where Q = radionuclide release rate from refinery stack (pCi/s) and A, = activity in the off-gases leaving the refinery stack in a year (pCi)
A,, = dust activity in refinery atmospheric effluent that passes through the baghouse filter (pCi)
RD = duration of release of refinery atmospheric effluent (s)
A, = radioactive decay constant (1/d) t, = time from clearance of material from nuclear facility to time scenario begins (d) l The dust radioactivity in the refinery atmospheric effluent that passes through the baghouse filter (A m) can be calculated from the mass of dust that passes through the filter and the radioactivity concentration in dust as follows. This is shown in Equation 4.16.
A ,, =
M ,, . Cs 4.16 where A,, = dust radioactivity in refinery atmospheric effluent that escapes the refinery baghouse in a year (pCi) and M,, = total mass of dust that escapes the refinery baghouse in a year (g)
C, = radionuclide concentration in dust after the refining process (pCi/g)
Atmospheric Dispersion Term The effluent dispersion of radioactive materials released into the atmosphere from a refinery facility is a function of several physical and environmental variables. For routine airborne Draft NUREG-1640, Vol. I 4-66
Section 4 Recycle and Disposal of Steel n'
f
. releases, the concentration of radioactive material at a given downwind locus depends upon the effluent emission rate, the effective height of the release, the average windspeed, atmospheric stability, airflow patterns at the site, and various effluent removal mechanisms.
Of the different approaches to modeling atmospheric dispersion, the straight-line Gaussian plume model (Slade 1968) is the most widely used method. In this model, the windspeed and atmospheric stability at the release point are assumed to determine the atmospheric dispersion characteristics in the mean wind direction at all distances. For effluent releases that are continuous or intermittent over long periods of time and, thus, subject to variations in wind direction, horizontal dispersion can be treated as an average over the width of a user-defined sector. The sector-averaged form of the Gaussian model (NRC 1977) used for this scenario is based on a sector width of 22.5 . The frequency of occurrence for windspeed and stability class are based on national-average data. This model treats the exposed group as residing in the downwind direction throughout the year. Atmospheric dispersion is given by Equation 4.17.
O 'H
= 2.032 Ej (FSC) j . [xu,0,l
- exp
-i r
g-l >
4.17
) where
/ x/Q =
annual average atmospheric dispersion factor (s/m')
and
=
FSC, fraction of time that stability classj occurs (dimensionless) x =
distance from release point to receptor (m)
=
u, average windspeed for stability class j (m/s) ,
o, =
vertical dispersion coefficient for stability classj at distance x (m)
= efTective stack height (m)
H.
The vertical dispersion coefficient, o,, is defined for each Pasquilt atmospheric stability class A-G and is a function of downwind distance, x. The Julich System, for an emission height of 50 m (164 ft)is used to define o,. According to Till and Meyer (1983), this system is applicable to sites with medium to high surface roughness, due to settlements, vegetation, and other ground obstacles. Equation 4.18 is used to calculate these coefficients for stability classes, SC, A-F and Equation 4.19 is used for stability class G.
0,= sc x" 4.18 where 04
= vertical dispersion coefficient for stability classj at distance x (m)
SC = stability class x = distance from release to receptor (m) 1 SC = 0.2222 (j = A,B)
O 0.2149 (j = C) 4-67 Draft NUREG-1640, Vol.1 l
r Recycl2 and Disposal of Steel Section 4 l
0.2048 0 = D) 0.1616 0 = E) 0.3960 0 = F) ,
n = 0.9680 0 = A, B) l 0.9438 0 = C) 0.9358 0 = D) i 0.8094 0 = E) j 0.6183 0 = F) 0,0 = 0.6 0,y 4.19 Equation 4.20 represents the air concentration of radionuclides at a distance x from the refinery.
0 0 0 4.20
-Q where x = the average effluent concentration, averaged over a sector 22.5* wide (pCi/m))
and XQ/ = annual average atmospheric dispersion factor (s/m')
Q = radionuclide release rate from refinery stack (pCi/s)
Ground-Surface Concentration Resulting from Atmospheric Releases O\ j Doses were calculated for external irradiation from nuclides deposited on the ground surface.
The ground-surface dose originates from a thin layer of radionuclides deposited on the ground surface from the passing plume. This concentration also includes the amount of radioactivity ,
that is weathered off plants. Therefore, the total deposition velocity, Vo(t), is used in Equation 4.21 to calculate the ground-surface radioactivity concentration.
-(4t) c ya-0v(r).1]3 a 4.21 where Cg = ground-surface radioactivity concentration (pCi/m2 )
and x
= the average effluent concentration, averaged over a sector 22.5' wide (pCi/m') i V,(T) = totaldeposition velocity (m/d) !
- t. = the period of long-term buildup for activity in soil (d) i A, = radioactive decay constant (1/d) i Draft NUREG-1640, Vol. I 4-68 O
p Section 4 Recycle and Disposal of Steel The volumetric radionuclide concentration in the soil is represented by Equation 4.22.
U C c,
4.22
.m " H3
- p,
! where Cuo, =
soil radionuclide concentration at time of scenario (pCi/g dry-weight soil) and Cg =
ground surface radionuclide concentration (pCi/m2 )
H, -
thickness of surface soillayer(m)
!- p, = ~ average density of soil in surface layer (g dry-weight soil /m')
- Concentration in Edible Parts of Plants j
- J
- The radionuclide concentration in the edible parts of plants at the time of harvest is described in Equation 4.23. This equation is used to calculate the concentration in leafy vegetables and !
l vegetables (for human consumption) due to direct deposition and root uptake. The concentration l of C-14 and H-3 in plants is calculated using Equations 4.24 and 4.25, respectively.
[d 1 -' B,' *r) W . (1 -c **)]
c" - 0
- v'(r>Y,Q 4.23 ,
QP \
f(
i N 77 where C, =
radionuclide concentration in edible part of plant v for consumption (i.e.,
. leafy vegetables and vegetables) due to root uptake and directly deposited material (pCi/kg wet-weight plant) and
= average effluent radionuclide concentration, averaged over a sector 22.5 x
! wide (pCi/m3 )
Vo(T) = total deposition velocity (m/d) i r = the fraction of total material being deposited that is intercepted by crops (dimensionless) .
A, = effective weathering and decay constant at harvest (1/d) (A, + L) t,, = the time period that crops are exposed to contamination during the growing season (d)
Y, = yield of plant v (kg wet-weight plant /m2 )
B, 3
= root uptake factor for radionuclide i from soil to plant v (pCi/kg dry-weight plant per pCi/kg dry-weight soil)
W,
= dry-weight-to-wet-weight conversion factor for plant v (kg dry-weight plant /kg wet-weight plant) 1, = radioactive decay constant (1/d)
- t. = the period oflong-term buildup for radioactivity in soil (d)
P =- areal soil density (kg dry-weight soil /m2 )
NJ 4-69 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 The concentration of C-14 in plants due to deposition is calculated using Equation 4.24.
' O 11' C,,c.,, - ( l .0E +03 ) p,.n * -
4.24 where C, c.u =
concentration of C-14 in edible part of plant v for consumption (i.e., all plants)
(pCi/kg wet-weight plant) and
=
x average effluent radionuclide concentration, averaged over a sector 22.5
- wide (pCi/m')
p .a = fractional equilibrium ratio (dimensionless) 0.11 = fraction of total plant mass that is natural carbon (dimensionless) 0.16 =
radionuclide concentration of natural carbon in the atmosphere (g/m')
1.0E+3 =
unit conversion factor (g/kg)
The concentration of H-3 in plants due to deposition is represented by Equation 4.25.
'05' C,,,,,3 = ( l .0E + 03 ) . (0.75 )
- U y 4.25 where C,.n.3 =
concentration of H-3 in edible part of plant v for consumption (i.e., all plants)
(pCi/kg wet-weight plant) and
=
x average effluent radionuclide concentration, averaged over a sector 22.5
- wide (pCi/m')
H =
absolute humidity of the atmosphere at receptor (g/m')
0.$ =
ratio of tritium concentration in plant water to tritium concentration in atmospheric water (dimensionless) 1.0E+3 = unit conversion factor (g/kg) 0.75 =
fraction of total plant mass that is water (dimensionless) i Plants for direct human consumption are considered to have a hold-up period before being consumed. The radionuclide concentration in plants at the end of the hold-up period is calculated using Equation 4.26 for all radionuclides including C-14 and H-3.
Co = C, e M 4.26 where
=
Co radionuclide concentration in edible part of plant v for human consumption at the end of the hold-up r riod (pCi/kg wet-weight plant) i and '
C, =
radionuclide concentration in edible part of plant v for consumption due to root uptake and directly deposited material (pCi/kg wet-weight plant)
=
A, radioactive decay constant (1/d)
=
- t. hold-up period between harvesting and consumption (d)
Draft NUREG 1640, Vol.1 4 70
Section 4 Rtcycle and Disposal of Steel 4.6.4.2 Drinking Water Concentrations
\
l - The drinking water pathway is included in residential scenarios and the slag storage scenario.
l Calculation of doses resulting from ingestion of drinking water requires calculating radioactivity l concentrations in the aquifer, i.e., the assumed source of drinking water. This section contains l the equations comprising the drinking-water model, starting with the surface layer. The total mass of waste in the surface layer, for landfill resident scenarios is calculated using Equation 4.27.
l M,=V,*0,*FW 4.27 where M. =
total mass of waste that is from cleared material in box 1 (surface layer)(g waste)
V. =
volume of all waste in landfill (m')
- p. = density of waste that is from cleared material (g waste /m2 )
FW =
fraction of total waste that is from cleared material The total initial radioactivity is calculated by multiplying the radioactivity concentration in the !
l waste for residential landfill scenarios, when leaching to the groundwater begins, by the total !
l mass of waste in the contaminated surface layer as shown in Equation 4.28.
I A i <o3 = C,,
- M, 4.28 l
where - l A go, = initial activity in box 1 (surface layer)(pCi) and C ,, = radionuclide concentration in waste when leaching to groundwater begins (pCi/g waste)
M. =
total mass of waste that is from cleared material in box 1 (surface layer) (g waste)
For the slag storage scenario, the total activity in the slag pile is represented by Equation 4.29.
Aigo, = CO+ M 4.29 t where A g,3 = initial radioactivity in box 1 (slag pile) (pCi) and~
Co.
= radionuclide concentration in the source material at the time the scenario begins (pCi/g)
M = total mass of material in box 1 (slag pile)(g) 4 71 Draft NUREG-1640, Vol. I L
I Recycle and Disposal of Steel Section 4 Once the initial radioactivity in the surface layer is calculated, the activities in each of the other two boxes (layers) in the model can be calculated. These activities are calculated as a function of time because radionuclides move through the boxes according to leach rate constants, which have units of d '. Leaching is assumed to begin immediately after placement of slag or waste, l prior to the beginning of the exposure scenario. The activity in box 1 (surface layer) as a function of time is expressed using Equation 4.30.
A ig ,3 =Ai go, e d a " '2)' 4.30 Box 1 in the groundwater model for scrap disposal scenarios consists of the scrap metal instead of the surface layer. Box 2 and box 3 still refer to the unsaturated zone and the aquifer, respectively. Therefore, Ago3, calculated by Equation 4.29, is defined as the initial acth'ity in the scrap metal at the time leaching to the groundwater begins. Equation 4.31 is used for scrap disposal scenarios to calculate activity in the surrounding soil at time t.
A y,) = A ,go,e ' E' - A , ,g,e "E ' '= )' 4.31 I
where Am = activity in the surrounding cover soil at time t (pCi) and i A m, -
initial activity in box 1 (scrap metal)(pCi) l 1, = radioactive decay constant (1/d) t = time from beginning of teaching to time activity is determined (d) ,
L., =
rate constant for movement of radionuclide from box 1 (scrap metal) to box 2 (unsaturated zone and cover soil)(1/d)
Equation 4.32 is used to calculate the activity in the unsaturated zone at time t. In scrap disposal scenarios, the rate constant L is substituted for Lu. L.,is also substituted for Lu in .
Equation 4.33. l 1 12 A l(o> ' (0, t n>< E 12Aljo) 3, ('I .
j*) _ ,-(a In): g (Or + E23) - (Or + Li2) (Or + L23 ) - ( Or + Li2)
The activity of the radionuclide in box 3 (aquifer) as a function of time is calculated using j Equation 4.33.
l l
i
, Draft NUREG-1640, Vol.1 4-72 O
1 1
-___-__-_-_-____-_0
p Section 4 Recycle and Disposal of Steel l ,r 3 - (0, - L 2 )'
i 7 23 712 t
A (o) l
. ^3"' ' [(0, + L23 ) - (0, + Li2 )] [(0, + w,) - ( 0, + Li2)] '
A 2(o) E 23 E12 23 _
A i(oi ,
- (0,
- In g (0, + w,) - ( 0, + L23) [(0, + L23 ) - (0, + Li2))[(0, + w,) - (0, + L23))
L 23 A 2(o) 123112 A l(o) ,):
() ( 0, + w,) - (0, + L23) ( ( 0, + w,) - ( 0, + Li2 )l [(0, + w,) -( 0, +L23)]
where
. Ano
=
activity in box ! (surface layer) at time t (pCi)
Ago = activity in box 2 (unsaturated zone) at time t (pCi)
Ayn =
activity in box 3 (aquifer) at time t (pCi) and Aug = initial activity in box 1 (surface layer)(pCi)
A, 3
= initial activity in box 2 (unsaturated zone)(pCi)
Aug - initial activity in box 3 (aquifer)(pCi) 1, = radioactive decay constant (1/d) l La = rate constant for movement of radionuclide from box 1 (surface layer) to box 2 '
(unsaturated zone)(1/d)
=
Lu rate constant for movement of radionuclide from box 2 (unsaturated zone) to box 3 (aquifer)(1/d) l
[
\
t w,
=
=
time from beginning ofleaching to time activity is determined (d) residential pumping rate constant from box 3 (aquifer) to box 2 (surface 'syer)(1/d) ,
l As described for previous equations, Box 1 can represent a slag pile, the surface layer, or scrap metal. The rate constants for movement of radionuclides from box 1 to box 2 are calculated using Equations 4.35,4.34, and 4.36. The rate constant for the movement of radionuclides from the scrap metal to the surrounding soil and to the unsaturated zone, L , was not calculated by Equation 4.34. Instead this value was input as a radionuclide-independent parameter. Two different pumping rate constants are used in Equation 4.33 depending on the scenario being analyzed. The residential pumping rate constant, w,, is used for the resident on closed landfill scenarios while w ois used for the storage of slag scenario.
I L 4'34 12 = HiiO Rti (365.25)
Di = ni fi 4.35 Kd iDi Rtg=1+ 4.36 O H O
1 i 4-73 Draft NUREG-1640, Vol. I
Recycle and Disposciof Steel S3ction 4 1
I l where L i2 = rate constant for movement of radionuclide from box i (surface layer) to box 2 1 (unsaturated zone)(1/d) I and l I = infiltration rate (m/y)
Hi = thickness of box 1 (surface layer)(m) 0, = volumetric water content of box 1 (surface layer)(dimensionless) i Rt i = retardation factor for movement of radionuclide from box ! (surface layer) to box 2 (unsaturated zone)(dimensionless) 365.25 = unit conversion factor (d/y) I ni = total porosity of box ! (surface layer)(dimensionless) !
fi - saturation ratio for box 1 (surface layer)(dimensionless)
Kd i =
soil / water partition coefficient far radionuclide in box 1 (surface layer)(mL/g) pi = bulk density of soil in box 1 (surface layer)(g/mL)
Equations used to calculate movement of radionuclides from box 2 to box 3 are shown below as Equations 4.37,4.38, and 4.39.
1 E '
23 " H2 U2 Rt2(365.25) 02" "2 /2 4 37 O,
2 02 R t,,
~
1+ 4.38 n2 where L23
rate constant for movement of radionuclide from box 2 (unsaturated zone) to box 3 (aquifer)(1/d) and 1 - infiltration rate (m/y)
H2 =
thickness of box 2 (unsaturated zone)(m) 02 =
volumetric water content of box 2 (unsaturated zone)(dimensionless)
Rt 2 =
retardation factor for movement of radionuclide from box 2 (unsaturated zone) to box 3 (aquifer)(dimensionless) 365.25 = unit conversion factor (dly) n2
= total porosity of box 2 (unsaturated zone) (dimensionless)
=
f saturation ratio for box 2 (unsaturated zone)(dimensionless)
Kd 2 = soil / water partition coefficient for radionuclide in box 2 (unsaturated zone)(mL/g) p2 = bulk density of soil in box 2 (unsaturated zone)(g/mL)
Pumping rate constants are calculated in order to estimate the amount of water pumped from the aquifer, using Equations 4.40 and 4.41.
Draft NUREG-1640, Vol.1 4-74 O
f[
l Section 4 Recycle and Disposal of Steel l
Vgg / VTJ w=a 4.40 T
F l
l where
= pumping rate constant from box 3 (aquifer) to surface (1/d)
- w. '
and- 1
=
Vu volume of water used for domestic purposes during a year (L)
=
Vu total water volume in box 3 (aquifer) (L) l T, = time period for pumping (d)
Vg+V, g V77 4,41 W' a T
P where w, =
residential pumping rate constant from box 3 (aquifer) to box I (surface lay er) (1/d) and V, = volume of water used for domestic purposes during a year (L)
V;,, =
volume of water used for irrigati<m purposes during a year (L) p V,7
= total water volume in box 3 (aquifer)(L) i T, = time period for pumping (d)
The concentration of radioactivity in the groundwater is calculated by dividing the total activity in the aquifer at the time the scenario begins by the total volume of water in the aquifer, as shown in Equation 4.42.
C, - A*3 4.42 VTr where C. = radionuclide concentration in groundwater (pCi/L) and Axo
= activity in box 3 (aquifer) at time t (pCi)
Vr, = total water volume in box 3 (aquifer)(L)
The value for the total volume of water in the aquifer is the greater of(1) the sum of the annual
- infiltration and annual irrigation volume or (2) the sum of the annual volume of water used for irrigation, the annual domestic water use, and the aquifer-fed surface-water pond volume. For some scenarios (e.g., storage of slag at the refinery), the total volume of water in the aquifer is i simply the greater of(1) the sum of the annual infiltration and the annual irrigation volume, or (2) the annual domestic water use.
O i
G 4 75 Draft NUREG 1640, Vol. I
Recycle and Disposal of Steel Section 4 The annual infiltration and irrigation volume is calculated using Equation 4.43. I 1
Vf7= I . A, . 1000 . Ti 4.43 where V,i = annual infiltration and irrigation volume through the cultivated farmland area (L)
And I = infiltration rate (m/y)
A, =
area ofland under cultivation (m )
2 1000 =
unit conversion factor (Um')
Ti = time period for infiltration and irrigation (y)
For the slag storage scenario, the annual infiltration and irrigation volume is calculated using Equation 4.44, where the area of contaminated land has been substituted for the area ofland under cultivation.
Vf , = I . Aj .1000. T, 4.44 i
where V,i = annual infiltration and inigation volume through the cultivated farmland area (L) and 1 I =
infiltration rate (m/y)
A, =
area of contaminated land (m )
2 1000 =
unit conversion factor (Um')
Ti =
time period for infiltration and irrigation (y) l l
The soil radionuclide concentration at the beginning oflandfill resident scenarios, after leaching has taken place, is calculated using Equation 4.45. The total mass of material in the landfill, QT, refers to the waste, daily cover-soil, and final cover-soil.
A 3 ")
= 4.45 Cs (t)
QT where C. =
soil radionuclide concentration at time resident moves onto landfill (pCi/g dry- !
weight soil) and A% = activity in box 1 (surface layer) at time t (pCi)
QT = total mass of material in box 1 (surface layer)(g dry weight soil)
For one scenario (resident on closed landfill after disposal of scrap metal) Equation 4.46 was used in place of Equation 4.45 to calculate soil radionuclide concentration where the total mass of material in the landfill is comprised of the daily cover-soil and final cover-soil.
Draft NUREG-1640, Vol. I 4-76 O
h l
l Section 4 Recycle and Disposal of Steel l 1
! Ch i
C'M =
A 'M gd QT 4.46 where Cg,3 = soil radionuclide concentration at time resident moves onto landfill (pCi/g dry-weight soil) and Ag =
activity in the surrounding cover soil at time t (pCi) i
= total mass of material in box 1 (surface layer) (g dry-weight soil)
QT 4.6.4.3 Food and Soil Concentrations j 1
The ingestion exposure pathway is analyzed in two parts using non-irrigation and inigation models. These two models can be used separately (i.e., growing plants in contaminated soil and )
irrigating with uncontaminated water or growing plants in clean soil offsite, but irrigating with i contaminated water) or they can be used together (i.e., growing plants in contaminated soil and l irrigating with contaminated water). Effective dose equivalents are calculated for each model separately; the total ingestion dose (non-irrigation plus irrigation) dose assumes both occur simultaneously.
Non Irrigation Ingestion Model for Resident on Closed Landfill Concentration /n edible parts of plant. The radionuclide concentration in the (n
1 edible part of the plant ofinterest at the time of harvest is described in Equation 4.47. This d
Equation is used to calculate the radionuclide concentration in vegetables for human !
consumption. 1 C,,, = 1000 - (ML, + Bg ) W, Cg e% 4.47 )
where -
C ., = radionuclide concentration in edible part of plant v for consumption due to root !
uptake and resuspended soil (non-irrigation .model)(pCi/kg wet-weight plant) !
and i B,, = root uptake factor for radionuclide I from soil to plant v (pCUkg dry-weight plant per pCi/kg dry-weight soil)
ML, = plant soil mass-loading factor for resuspended soil to plant v (pCi/kg dry-weight l plant per pCi/kg dry-weight soil)
W, = dry-weight-to-wet weight conversion factor for plant v (kg dry-weight plant /kg wet-weight plant)
C. = soil radionuclide concentration at time resident moves onto landfill (pCi/g dry weight soil)
A, = radioactive decay constant (1/d )
t,, = growing period for plant v (d) 1000 = unit conversion factor (g/kg)
)
V 4 77 Draft NUREG-1640, Vol. I t
I l
Recycle and Disposal of Steel Section 4 l
l The soil radionuclide concentration at the time the resident moves onto the landfill, C , is !
calculated using Equation 4.45; Equation 4.46 is used for disposal of metal. Plants for direct )
human consumption are considered to have a hold-up period before being consumed. The radionuclide concentration in plant v at the end of the hold-up period is calculated using ;
Equation 4.48. i M 4.48 C y,,,;, = C y,,, e where C, = radionuclide concentration in edible part of plant v for human consumption at end of hold-up period (non-irrigation medel)(pCi/kg wet-weight plant) and C,.', =
radionuclide concentration in edible part of plant v for consumption due to root uptake and resuspended soil (non-irrigation model)(pCi/kg wet-weight plant)
A, = radioactive decay constant (1/d)
= hold-up period between harvesting and consumption (d) t.
Irrigation ingestion Model for Resident on Closed Landfill Concentration in edible parts of plant. There are two ways for contamination to enter the plant, direct deposition ofirrigation water on the plants and direct deposition ofirrigation water on the soil, with subsequent root uptake into the plant. Each of these radionuclide concentrations are calculated separately.
The rate of direct deposition ofirrigation water onto plants is calculated using Equation 4.49.
IR = r"
- T" = C" R = 4.49 v.P yv where R,., =
rate of deposition of irrigation water onto plant v (pCi translocated /kg-d) and IR = average annual application rate ofirrigation water (L/m2 -d) r, = fraction ofinitial deposition of irrigation water retained on plant v (pCi retained'pCi deposited)
T. =
fraction of retained activity translocated to edible part of plant v (pCi translocated'pCi retained)
C. =
radionuclide concentration in groundwater (pCi/L)
Y, =
yield of plant v (kg wet-weight plant /m2 )
The radionuclide concentration in plants, due only to direct deposition ofirrigation water at the time of harvest, is calculated using Equation 4.50.
Draft NUREG-1640, Vol.1 4-78 O
p i Section 4 Recycle and Disposal of Steel I 1 - c *F yi C,,y = R,, p ,
4.50 Ue where C,a =
. radionuclide concentration in edible part of plant v at time of harvest due to direct deposition of irrigation water (pCi/kg wet-weight plant) and R,, =
rate of deposition ofirrigation water onto plant v (pCi translocated /kg-d)
( =
effective weathering and decay constant at harvest (1/d)(( + A)
L = weathering constant at harvest (1/d)
A = radioactive decay constant (1/d) t, -
growing period for plant v (d)
Deposition onto soil and subsequent root uptake is also modeled. The rate at which irrigation water is deposited onto the soil is calculated using Equation 4.51.
IR C" R' = 4.51 P
where R, =
rate of deposition of irrigation water onto soil (pCi/kg dry-weight soil- d)
IR = average annual application rate ofirrigation water (Um2 -d)
C. =
radionuclide concentration in groundwater (pCi/L)
P = areal soil density (kg dry-weight soil /m2 )
The radionuclide concentration in the soil at the end of the growing season is calculated using Equation 4.52.
1 -c F Csg =R s 4.52 Ur where C,, = soit radionuclide concentration at end of growing se'ason due to direct deposition of irrigation water (pCi/kg dry-weight soil) and R, = rate of deposition ofirrigation water onto soil (pCi/kg dry-weight soil - d) l A = radioactive decay constant (1/d) t,
= growing period for plant v (d)
The radionuclide concentration in the edible part of the plant at the time of harvest (only from deposition onto the soil and root uptake) is calculated using Equation 4.53.
4-79 Draft NUREG 1640, Vol.1 I l
i
Recycle and Disposal of Steel Section 4 C,,,,, = (ML, + B;,) W,, . C,g 4,53 where C,.,4 = radionuclide concentration in edible part of plant v at time of harvest due to root uptake (pCi/kg wet-weight plant) and ML, = plant soil mass-loading factor for resuspended soil to plant v (pCi/kg dry-weight plant per pCi/kg dry-weight soil)
B,, = root uptake factor for radionuclide i from soil to plant v (pCi/kg dry-weight plant per pCi/kg dry-weight soil)
W. = dry-weight-to-wet-weight conversion factor for plant v (kg dry-weight plant /kg wet-weight plant)
C, = soil radionuclide concentration at end of growing season due to direct deposition of irrigation water (pCi/kg dry-weight soil)
Finally, the total radionuclide concentration in the edible parts of plants, following deposition via irrigation and after the hold-up period, is calculated using Equation 4.54.
M 4.54 C y,,3 = ( C y,;g + Cy,p,;) . c where C,3 = total radionuclide concentration in plant v after hold-up period (irrigation model)
(pCi/kg wet-weight plant)
C,y = radionuclide concentration in edible pa:t of plant v at time of harvest due to direct deposition of irrigation water (pCi/kg wet-weight plant)
C,.,, = radionuclide concentration in edible pan of plant y at time of harvest due to root uptake (pCi/kg wet-weight plant)
A, = radioactive decay constant (1/d)
- t. = hold-up period between harvesting and consumption (d) 4.6.5 Exposure Pathway Doses This section presents the equations used to calculate pathway doses, using the media radionuclide concentrations described in Section 4.6.4, as well as other parameters described in other sections.
4.6.5.1 External Exposure Pathway When external exposure is due to penetrating radiation from an object such as a drum or pile, then it is calculated using Equation 4.55 which assumes that a worker is in close proximity to the object. The parameter GF is a nuclide- and scenario-specific dose rate factor. The values of GF incorporate information on the photon spectrum of each nuclide and the size, mass, shape, and elemental composition of objects such as drums or piles of material. For each nuclide and object, GF has a fixed value. Calculation of GF is discussed in Appendix C. The parameter Uor is a multiplicative factor which carries the uncertainty information about each GF. The range and ;
mode of each Uce are based on uncertainty in the mass of the object and the relative position of !
Draft NUREG-1640, Vol.1 4-80
)
I 1
1
Section 4 Recycle and Disposal of Steel g the exposed individual. This equation is used for scenario categories such as handling, processing, storage, transportation, and product use.
D = C iGF o ~ UGF
- 'n
- Iy, A 55 where D, = EDE due to external exposure (mrem /y) and
=
C. radionuclide concentration in the source material at the time xenario begins (pCi/g waste) '
GF =
geometry factor for the scenario (mrem /h per pCi/g) to -
daily number of hours of exposure for scenario (h/d)
=
t,y annual number of days of exposure for scenario (d/y)
Un = uncertainty factor for GF (dimensionless)
Federal Guidance Report No.12 (EPA 1993a) provides dose rate factors for certain simple geometries such as an infinite plane of soil contaminated to various depths. These values have been use'd for scenarios in which the geometry of the source is similar to one specified in Federal Guidance Report No.12. Equation 4.56 is used for the disposal activities scenarios.
D, = C o* Ugp
- DF,
- SF
- 0,
- t,
- t y,
- 360c 4.56 O where D., =
EDE due to external exposure (mrem /y) and
=
C. radionuclide concentration in the source material at the time scenario begins (pCi/g waste)
DF , =
external dose rate factor for contamination ofinfinite depth (mrem-m 8/pCi-s)
SF = vehicle shielding factor (dimensionless) p, = density of waste from cleared material (g waste /m')
= daily number of hours of exposure for scenario (h/d) t.
=
t, y annhal number of days of exposure for scenario (d/y) 3600 =
unit conversion factor (s/h)
U. -
uncertainty factor for dose rate factor (dimensionless)
Equation 4.57 is used to calculate the dose to a resident on a closed landfill due to both outdoor and indoor external exposure, where contamination is distributed volumetrically in soil.
D, = (tg*SFO C,<,3
- 0,
- Uce
- DF,
- 86400) +
4.57 (tu
- SFI
- C,c,3 0,
- Uce
- DF,
- 86400) whre D., = EDE due to external exposure (mrem /y) 4-81 Draft NUREG 1640, Vol. I
Recycle and Disposal of Steel Section 4 and SFO = shielding factor during outdoor activities (dimensionless)
SFI = shielding factor during indoor activities (dimensionless)
C. = soil radioauclide concentration at time resident moves onto landfill (pCi/g dry-weight soil) p, = average density of soil in surface layer (g dry-weight soil /m' )
DF., = extemal dose rate factor for contamination of soil ofinfinite depth (mrem-m8 per pCi-s) 86400 =
unit conversion factor (s/d) tw = annual number of days spent outdoors (d/y) ta = annual number of days spent indoors (d/y)
Uc, = uncertainty factor for dose rate factor (dimensionless)
Equation 4.58 is to calculate external exposure due to ground-surface radionuclide concentrations of radionuclides. This equation is used for external exposure due to atmospheric releases from a refinery.
Da - (tog
- SFO +
t;g
- SFI)
- Cp g
- DFp,
- UGF
- ObA00 A 58 where D., = EDE due to external exposure (mrem /y) and ta = annual number of days spent outdoors (d/y)
SFO = shielding factor during outdoor activities (dimensionless) ta = annual number of days spent indoors (d'y)
SFI = shielding factor during indoor activities (dimensionless)
Cg = ground surface concentration of radionuclide at time of scenario (pCi/m2 )
DFg = external dose rate factor for exposure to contaminated ground surface (mrem /s per pCi/m2)
Uc, = uncertainty on geometry factor (dimensionless) 86400 =
unit conversion factor (s/d)
For the transportation scenarios, the potential external doses for the truck driver are calculated using Equation 4.59.
D,, - (GF
- Co )
- t,
- t,,
- Ucy 4.59 where:
Dot = EDE due to external exposure for individual (mrem /y)
GF = geometry factor for the scenario (mrem /hr per pCi/g)
Co = radionuclide concentration in the source material at the time the scenario begins (pCi/g) t.
= daily number of hours of exposure for the scenario (h/d) t, y
= annual number of days of exposure for the scenario (d'y)
Uc, = uncertainty factor for dose rate factor (dimensionless)
Draft NUREG 1640, Vol.1 4-82 O
Section 4 Recycle and Disposal of Steel 1
/q 4.6.5.2 inhalation Exposure Pathway 4
V Work-re/ated. In some worker scenarios, a fraction of the material (e.g., metal i
I shavings, slag, and EAF dust) would be suspended into the air, making it available for inhalation by a worker at a steel refinery. The dose due to this exposure pathway is calculated using Equation 4.60.
D;,,y - Co . ML
- RF
- BR
- PF = DF;,5 * (lE-03)
- t,
- t,,, 4.60 where D., =
EDE due to inhalation (mrem /y) and
=
Co radionuclide concentration in the source material at the time the scenario begins (pCi/g)
ML =
mass loading of the source material (mg/m')
RF =
respirable fraction of resuspended source material (dimensionless)
BR =
breathing rate for moderate physical activity (m'/h)
DF,. =
inhalation dose factor (mrem /pCi intake)
PF =
protection factor for respirator (dimensionless) lE-3 =
unit conversion factor (g/mg)
=
t, daily number of hours of exposure for scenario (h/d) :
ty =
annual number of days of exposure for scenario (d/y)
/~N
(
U
) Land /i// resident. To estimate inhalation exposure for the scenarios involving a resident on a closed landfill, Equation 4.61 is used. This equation is used to calculate the total inhalation dose due to indoor, dusty, and non-dusty activities.
D;ng = (BR g ,,, tag
- MLg,,,
- C,y,
- DFinh
- 24)
+ ( BR,,, * (t,g - tsg)*MLou ,*C,9, *DFinh
- 24) 4.61
+ ( BR;,,
- t;g * (ML;,, + gP = RF,)
- C,9,
- DF;,y
- 24) where D, =
EDE due to inhalation (mrem /y) and C. = soil radionuclide concentration at time resident moves onto landfill (pCi/g i dry-weight soil) ;
MLu = mass loading factor for resuspended soil for dusty activities outdoors (g/m' ) )
ML. =
mass loading factor for resuspended soil for normal activities outdoors (g/m2 ) 1 ML, = mass loading factor for resuspended soil blown indoors from outdoors (g/m' ) i P.
= indoor dust-loading on floors (g/m2 )
RF, = indoor resuspension factor (!/m)
BR. = breathing rate for dusty activitics outdoors (m'/h)
BR. = breathing rate for normal activities outdoors (m'/h)
BR. = breathing rate for indoor activities (m'/h)
[, DF. = inhalation dose factor (mrem /pCi intake)
(s 4-83 Draft NUREG-1640, Vol.1 l
Recycle and Disposal of Steel Section 4 24 =
conversion factor (h/d)
=
tu annual number of days spent on dusty activities outdoors (d/y)
=
t,o annual number of days spent outdoors (d/y)
=
t,4 annual number of days spent indoors (d/y)
Atmospheric Releases Inhalation doses resulting from refinery releases are calculated for inhalation of airborne radionuclides at a residence (from the passing plume) and inhalation of suspended soil (dust).
Like the external pathway, an individual's time is divided between offsite and onsite, and while onsite, indoors and outdoors. The EDE due to inhalation includes the radioactivity inhaled as a result of the passing plume and from suspension of the soil. This is represented by Equation 4.62.
D, = +
A,,)
- DF, 4.62 (A,,,
where D,,,. =
EDE due to inhalation (mrem /y) and s
Ag. =
activity inhaled directly from the passing plume in a year (pCi/y)
A,. =
activity inhaled due to resuspension of soil in a year (pCi/y)
D F,,,, =
inhalation dose factor (mrem /pCi intake)
The activity inhaled directly from the passing plume is represented by Equation 4.63. The average effluent radionuclide concentration used in this equation is calculated using Equation 4.20.
A,,, = ( (BR,
- RFI ty) +
(BR,,
- ta) )
- 24 0 4.63 where As,, =
activity inhaled directly from the passing plume in a year (pCi/y) and B R,, =
breathing rate for indoor activities (m%)
RFI -
indoor fraction of outdoor radionuclide concentration t,, -
annual number of days spent indoors (d/y)
BR. =
breathing rate for normal activities outdoors (m%)
=
t, o annual number of days spent outdoors (dly)
=
x average effluent radionuclide concentration, averaged over a sector 22.S
- wide (pCi/m2 )
24 =
unit conversion factor (h/d)
Doses due to inhalation of radionuclides in resuspended soil (dust) at a residence will also be calculated. A fraction of an individual's time at the residence will be spent indoors, during which the individual will breathe dust blown in from outdoors as well as dust tracked inside then resuspended. During the fraction of the time spent outdoors onsite, the individual's time will be '
Draft NUREG-1640, Vol.1 4-84 O.
E Section 4 Recycle and Disposal of Steel p)
(v divided into time spent engaged in activities that could generate dust (such as sweeping, playing sports, and gardening) and time spent engaged in other outdoor activities (such as walking, sunbathing, and washing windows). Equation 4.64 represents the activity inhaled as a result of resuspension of the soil.
i l A, =
[ (BRj ,, . t j, MLj ,,) + (BR,, - a(t - tjj) . ML,,)
l C# 4.64
+ (BR, ty. 24]
{ML, + P, . RF,} ) ] . [ D,
- RL where I A,, =
radioactivity inhaled due to resuspension of soil in a year (pCi/y) and BRu = breathing rate for dusty activities outdoors (m8 /h)
BR. = breathing rate for normal activities outdoors (m 8/h)
BR,, = breathing rate for indoors activities (m8 /h)
=
tu annual number of days spent on dusty activities outdoors (d/y)
= annual number of days spent outdoors (d/y) l ta t,, = annual number of days spent indooa (d/y)
ML. =
mass loading factor for resuspended soil for dusty activities outdoors (g/m')
ML. = mass loading factor for resuspendedtoil for normal activities outdoors (g/m') l M L,, =
mass loading factor for resuspended soil blown indoors from outdoors (g/m') i RF, = indoor resuspension factor (1/m)
P, = indoor dust-loading on floors (g/m2) l s C, p = . ground surface radionuclide concentration (pCi/m 2)
\ p, = average density of soil in surface layer (g/m')
RL =
thickness of soil layer available for recuspension (resuspension layer)(m) 24 =
unit conversion factor (h/d) 4.6.5.3 Inadvertent Secondary ingestion Exposure Pathway l Material that is resuspended can be deposited as surface contamination. Secondary ingestion includes ingestion of radioactive material from contaminated hands and food. This is a relatively poorly defined pathway that is not easily calculated by a detailed description of the mechanisms involved. The dose from this exposure pathway is calculated using Equation 4.65.
D, = C o* IR = DF4
- t,
- t,,, 4.65 where D,, = EDE due to secondary ingestion (mrem /y) and C. = radionuclide concentration in the source material at the time the scenario begins (pCi/g) 1R = secondary ingestion rate (g/h)
{ DF% = ingestion dose factor (mrem /pCi intake)
I to = daily number of hours of exposure for scenario (h/d) t, y
= annual number of days of exposure for scenario (dly) jv
, 4-85 Draft NUREG-1640, Vol. I
r Recycle and Disposal of Steel Section 4 4.6.5.4 Water ingestion The drinking-water dose (from ingesting contaminated groundwater) is calculated using Equation 4.66. The radionuclide concentration in groundwater, C., is calculated using Equation 4.42 Ddu=C,.U,.DFjyg
- 365.25 4.66 where
=
Du EDE due to ingestion of drinking water (mrem /y) and C. =
radionuclide concentration in groundwater (pCi/L)
U. =
human consumption rate of water (L/d)
DF , =
ingestion dose factor (mrem /pCi intake) 365.25 = unit conversion factor (d/y) 4.6.5.5 Ingestion of Food Effective Dose Equivalent Due to ingestion of Non-Irrigated Foods-Resident on Closed Landfill In the non-irrigation model, the dose from ingestion of contaminated plants is calculated using Equation 4.67.
D =
DIET, . ( C;,,,y s U;, + C y,,,,s
- U,,,)
4.67 ;
+(Cm *Uwjf
- 1000) f *j DF,g where D. ., =
EDE due to non-irrigation ingestion model of plants (i.e., leafy vegetables and vegetables)(mrem /y) and DIET, =
fraction of annual diet from non-irrigated plants (dimensionless)
C. -
soil radionuclide concentration at time resident moves onto landfill (pCi/g dry-weight soil)
C,,, =
radionuclide concentration in edible part ofleafy vegetables aRer hold-up period j (non-irrigation model)(pCi/kg wet-weight plant) '
C., =
radionuclide concentration in edible part of vegetables aner hold-up period (non-irrigation model)(pCi/kg wet-weight plant)
Uu =
human consumption rate of soil (kg dry-weight soil /y)
U,, =
human consumption rate ofleafy vegetables (kg wet-weight plant /y)
U,,, =
human consumption rate of vegetables (kg wet-weight plant /y)
DF., =
ingestion dose factor (mrem /pCi intake) 1000 =
unit conversion (g/kg)
Draft NUREG-1640, Vol.1 4-86 91 l
Section 4 Recycle and Disposal of Steel p Effective Dose Equivalent Due to irrigation Ingestion Model-Resident on 1
i ( - Closed Landfill
, O l The EDE for the irrigation ingestion model is calculated using Equation 4.68. All plant radionuclide concentrations and human consumption rates of plants are in wet-weight while soil i
radionuclide concentrations and human consumption rates of soil are in dry-weight. I D g,,,,, = DIET,, = (C;,,,s
- U g, + C,,,,;;, U,,, )
4.68
+ (C,g
- Ugf )
- DF ,,g j where D, =
EDE due to irrigation ingestion model ofirrigated plants (mrem /y) ,
and 1 DIETi =
fraction of annual diet from irrigated plants (dimensionless)
=
Ci .. radionuclide concentration in edible pan ofleafy vegetables after hold-up period (irrigation model)(pCi/kg wet-weight plant)
C# =
radionuclide concentration in edible part of vegetables after hold-up period (irrigation model)(pCi/kg wet-weight plant)
C, =
soil radionuclide concentration at end of growing season due to direct deposition of irrigation water (pCi/kg dry-weight soil)
U,, =
human consumption rate ofleafy vegetables (kg wet weight plant /y)
U, =
human consumption rate of vegetables (kg wet-weight plant /y) ;
} Ua =
human consumption rate of soil (kg dry weight soil /y)
V DF, =
ingestion dose factor (mrem /pCi intake)
Effective Dose Equivalent for Total Ingestion Model The TEDE for the ingestion model assumes that the vegetables are grown on contaminated soil and are spray irrigated with contaminated groundwater. The total dose, non-irrigation plus irrigation, is calculated using Equations 4.69,4.70, and 4.71, below. All plant radionuclide concentrations and human consumption rates of plants are in wet-weight while soil radionuclide concentrations and human consumption rates of soil are in dry-weight.
PF,, = Ug ,
- Cg ,,y + U,,, C,,,,n 4.69 PF, = + Ug ,
- Cg,,,y + U,,,
- C,,,;p 4.70
- Oy
( Q 4-87 Draft NUREG 1640, Vol. I m
Recycle and Disposal of Steel Section 4 1
D g,,, = DIET * (PF,, + PF,)
4.71
+ (C,,,,
- U,,;g 1000 ) + (C,,
- U,,;;)
- DF,,,,
where PF, = activity uptake from non-irrigation model (pCi/y)
PF, = activity uptake from irrigation model(pCi/y)
D., = EDE due to ingestion (non-irrigation and irrigation models) (mrem /y) and U,, = human consumption rate ofleafy vegetables (kg wet-weight plant /y)
U,,, = human consumption rate of vegetables (kg wet-weight plantly) ,
U.,i = human consumption rate of soil (kg dry-weight soil /y)
= radionuclide concentration in edible part ofleafy vegetables after hold-up period Cw.4 (non-irrigation model)(pCi/kg wet weight plant)
C,,a = radionuclide concentration in edible part of vegetables after hold-up period (non-irrigation model)(pCi/kg wet-weight plant)
=
Cw,,,, radionuclide concentration in edible part ofleafy vegetables after hold-up period (irrigation model)(pCi/kg wet-weight plant)
C,,,n = radionuclide concentration in edible part of vegetabics after hold-up period (irrigation model)(pCi/kg wet-weight plant)
=
Cuo soil radionuclide concentration at time resident moves onto landfill (from non-irrigation model)(pCi/g dry weight soil)
=
C., soil radionuclide concentration at end of growing season due to direct deposition of [
irrigation water (pCi/kg dry-weight soil) )
1000 = unit conversion factor (g/kg) )
= ingestion dose factor (mrem /pCi intake)
DF,,,, !
1 Effective Dose Equivalent Due to ingestion of Foods and Soil-Refinery Stack )
Releases The TEDE from ingestion of contaminated plants, and soil is calculated using Equation 4.72.
D,= DIET (C .h iv
- Ulv + C,,,, = U,,,, )
l 4.72
+ ( C ,(o)
- Ugig
- 1000) f
- DF,,,g l
where DIET = fraction of annual diet derived from home-grown foods (dimensionless) l C,o = soil radionuclide concentration at time of scenario (pCi/g dry-weight soil)
= radionuclide concentration in edible part ofleafy vegetables after hold-up period Cw3 (pCi/kg wet-weight plant)
C,,o = radionuclide concentration in edible part of vegetables after hold-up period (pCi/kg wet-weight plant)
U,a = human consumption rate of soil (kg dry-weight soil /y)
= human consumption rate ofleafy vegetables (kg wet-weight plant /y)
Uw Draft NUREG-1640, Vol.1 4-88 l l
E Section 4 Recycle and Disposal of Steel U, =
human consumption rate of vegetables (kg wet weight plant /y) s} DF, = ingestion dose factor (mrem /pCi intake) j 1000 = unit conversion (g/kg) 4.7 Derived Surficial Dose Factors At the time of clearance, residual radioactivity may initially be distributed on the surface or throughout the volume (mass) of the cleared material. All of the scenarios discussed in this section treat residual radioactivity as volumetrically distributed throughout the mass of scrap or i refinery product such as slag or baghouse dust. This is because, once the material has been I processed, radioac_tivity is redistributed throughout the entire volume regardless ofits initial )
distribution. _ Even " unprocessed" scrap that has not yet been melted at a refinery can be treated
{
as volumetrically contaminated. Consistent with industry practices, scrr.p that is ready for :
release would be sized and sorted for efficient loading onto trucks. The residual radioactivity l associated with large piles or truck loads of such scrap would be effectively distributed I throughout the volume even ifit were present only on the surfaces ofindividual pieces of equipment or scrap metal.
The mass-based dose factors for each recycle scenario indicate the annual dose to an individual from residual radioactivity distributed throughout the mass of cleared material. The derived surficial dose factor indicates the annual dose to an individual exposed under the same conditions from radioactivity that was initially distributed over the surface of the cleared material. A derived surficial dose factor for each scenario is calculated using the surface-to-mass ratio of the
- cleared object or material according to Equation 4.73.
Dose Factor, = SM
- Dose Factor _ 4.73 I
l where '
Dose Factor w = 2 derived surficial dose factor (mrem /y per pCi/cm )
and SM = surface-to-mass ratio (cm2 /g) l Dose Factor _ = mass-based 6se factor (mrem /y per pCi/g)
The surface-to-mass ratio of objects and materials available for clearance can vary over a wide range. This is due, in part to the different surface-to-volume ratios of various objects such as pipes, sheets, and bar stock. It is also the result of different densities among various materials.
The parameter SM is represented by a distribution of values that incorporate the variability and uncertainty in the surface to-mass ratio of objects available for clearance. The distributions used for the surface-to-mass ratios are chosen as appropriate for each material in the analysis (see l Section 4.8.5).
4-89 . Draft NUREG 1640, Vol.1 L
L
Recycle and Disposalof Steel Section 4 4.8 Parameter Discussion Calculation of potential impacts from reuse or recycle of cleared licensee scrap material depends on many parameter values. Parameter values are needed for both material flow and dose assessment models. The material flow carameter values rely on information from the U.S.
secondary steel industry. The parameter values for the dose modeling rely on receptor behavior infonnation, such as time on a specific job or breathing rate, as well as environmental transport of radionuclides. Parameter values used for the assessment ofimpacts are discussed in the following sections and are tabulated as appropriate in this section. Although not a parameter value, a description of the selection of radionuclides is also provided in this section.
To support the probabilistic nature of the dose calculations, a range and assumed distributional shape was used for most parameter values in the dose modeling. Parameter value distributions are intended to capture uncertainty and variability in the parameter values for the exposed groups described for each scenario. Each exposed group is relatively homogeneous in characteristics that are relevant to the calculated dose factors. Therefore, most of each parameter range is due to uncertainty rather than variability among individuals.
In some cases, only nominal parameter values are discussed, not the ranges. If only a nominal >
value is discussed, it is generally a "most likely value"(i.e., fixed value or the mode of a distribution), or an estimate of central tendency (e.g., a mean value). A complete listing of parameter distributions and their characteristics is provided in Appendix B.
The quality of underlying data varies among the parameters used in the analyses. In some cases, appropriate data were available and were used as a basis for a realistic parameter value range. In other cases, appropriate data were not readily available, and professional judgement was more heavily relied on to determine a parameter range. Appendix B describes the data quality conventions and levels used in this analysis.
4.8.1 Radionuclide Selection Several recent sources were reviewed to identify those radionuclides that are most likely to be found in equipment and material cleared from an NRC licensed facility. Rather than use lists from previous similar assessments, developing the list independently of previous studies helped ensure that radionuclides ofinterest would not be overlooked-or included-because of convention. The list (presented in Table 4.9) was compiled from the following five sources:
NRC correspondence with IAEA (Meck 1992). Radioactive contamination in recycled or re-used material is likely to be similar to that oflow level waste currently disposed. Radionuclides listed in this reference constitute greater than 90 percent of the radioactivity disposed of by U.S.
commercial sites during the three years 198?, through 1990.
1992 State-by-State Assessment of Low-Level Radioactive Wastes Received at Commercial Disposal Sites (Fuchs and Mcdonald 1993). This document lists those radionuclides that were disposed ofin 1992 at commercial low level disposal sites from various sources: nondirect Draft NUREG-1640, Vol. I 4-90 O
Section 4 Recycle and Disposal of Strei
.(shipments from the generator to the disposal facility through an intermediary), reactors, (n
%)
l academic, medical, industrial, and government.
Rs:Neuclides in United States Commercial Nuclear Power Reactors (Dyer 1995). This article presents data from several studies on the amounts and types of radionuclide activities found in nuclear power plant systems and materials (specifically stainless steel). The study considered only those radionuclides with half-lives longer than 50 days.
. Special activation products in certain materials. Some radionuclides not listed in the previous three sources are activation products for certain materials. The materials considered for this study were steel, copper, aluminum, and concrete.
Radioactive progeny of radionuclides on the list. Potentially significant (halflife greater than I day) radioactive progeny from parent radionuclides identified in the sources listed above were included explicitly on the list. Radioactive progeny with half-lives ofless than I day are excluded from the list because their emissions would be insignificant by the time of the first exposure scenario,4 days post-clearance. The effects of progeny radionuclides are included with the parent radionuclides listed in Table 4.9; these are described in Appendix E.
Radionuclides excluded. Radionuclides with half-lives longer than Th 232 (greater than 1,41E+10 years) were not included in the analysis. Emissions from these redionuclides (e.g.,
Sm-147) would be insignificant during the relatively short time periods that are assumed for the scenarioc. Two radionuclides listed above (Y-90, Kr-85) meet the criteria for inclusion, however, these radionuclides are not included in final dose tables because it seems unlikdy that q
they would be found in the equipment or material cleared from an NRC licensed facility addressed in this study. The short radioactive half-life of %90 (64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br />) makes it unlikely that is would be in any cleared material except in equilibrium with its parent Sr-90, and Kr-85 is a noble gas and would not exist as residual radioactivity in cleared material.
Table 4.9 Radionuclides ofinterest for recycle, disposal, and reuse of equipment and materials H 3 ") Co-58 m Y-91 m I 125 "' Eu-155
- Ac-227
- U-234 "'
C-14 m Fe-59 "8 Mo-93 m Sb-125 m Re-186 m Th-227 m U 235 m Na-22 m Ni-59 m Nb-93mm I-129 m Ir 192 m Th-228 m Np-237
- P-32 m Co-60 m Nb-94
- I-131 m Pb-210 m Ra-228 m . Pu-238 m S-35 m Ni-63 m Nb-95 m Ba-133 m Po-210 m Th-229 m U-238m Ci-36 m Zr-65 m Zr-95 m Cs-134 m Bi-210 m Th-230 m Pu-239 m K-40 m Cu-67 m Tc.99 m Cs-137 m Rn-222 m Pa-23i W Pu-240 m Ca-41 m Se-75 m Ru-103 m Cc-141m Ra-223
- Th-231
- Pu-241 m Ca-45 m Kr 85 m Ru-106 m Ce-144 m Ra-224 m Th-232 m Pu-242 m Cr-51 m ' Sr-85 m Ag-108mm Pm-147 m Ac-225 m Pa-233 m Am-241 m Mn-54 m Sr-89 m Cd-109 m Eu-152 m Ra-225 m U-233 m Cm-242 m Fe-55 m Sr-90 m Ag-l10m W Eu-154 m Ra-226 m Th-234 m Cm 244
- Co-57 m Y-90 m Sb-124 m (1) Meck (1992); (2) Fuchs and Mcdonald (1993); (3) Dyer (1995); (4) special activation product; (5) radioactive progerg; (6)added in review process.
J DratlNUREG-1640, Vol. l 4-91 I,
i Recycl; and Disposal of Steel Section 4 4.0,2 Material Flow Model The parameter values used in the matenal flow model are presented in Appendix B and are based
< on the information presented in Sections 4.2 and 4.3 of this report. The values are based on recycling material cleared from an NRC licensed facility for 1 year in the existing, commerdal {
iron and steelindustry. j 4.8.3 Scenario Timmg This section presents the basic assumptions used in derming the nominal time periods for each of l the recycle scenados. All exposure scenarios were derived from the material flow conceptual modeling, and scenarios were assumed to occur at specH'c points in time following clearance.
This basis was used to defire the parameter t,, the time from clearance of material to the time the
. scenario begins. Where a reference was used as a basis for the assumed time period, it is cited.
If no citation is given, general knowledge of practices gained from talking w95 industry personnel combined with professionaljudgement was used as the basis. A uniform distribu: ion was used with a range of 50% of the nominal value. The following is a list of basic assumptions that ' vere used in developing nominal values for the timing of the scenarios: j
\ l Scrap Handling: i 1
- All scrap metal is assumed in be initially taken to a scrap dealer. It takes 4 days for the l scrap metal to reach the scrap dealer. l
- The scrap metal remains at the scrap dealer for a period of 7 days prior to reuse or disposal, and 25 days for scrap metal that is recycled.
OI Refining and Processing:
= For recycled scrap metal the refming process and associated product manufacture, final processing, and any onsite storage at the refinery is assumed to take a total of 11 days for an EAF (O'Donnell et al.1978) and 15 days for BOF.
. Following initial processing, BOF products undergo further processing before use; this secondary processing, plus storage and handling, is assumed to take 22 days.
- EAF metal produ ts are distributed to the public upon completion of the refinery process while BOF products are distributed for use upon completion of the secondary process.
Distribution for both products is assumed to take 7 days.
- Releases of radionuclides in the atmospheric effluent from an EAF or BOF refinery occur at the time the scrap is refined, i.e.,29 days after clearance.
Draft NUREO-1640 Vol.1 4-92 O l l
r, Section 4 Recycle and Disposal of Steel
, Use and Dispossh
- An EAF metal product is used for 30 years, based on an assumed use in the construction industry. Use of a BOF metal product is 10 years, based on an assumed general purpose use (IAEA' 1992).
l l
- EAF and BOF refinery slag and baghouse dust are produced at the time refining occurs, 29 days after clearance of scrap metal from the licensee.
=
Refinery slag that is sold for subsequent use is processed at the refinery 3 days after production and leaves the refinery in another 2 days. Slag is assumed to be used within 2 days after distribution and is used for a period of 30 years. Once the period of use is completed, the products are disposed in a sanitary landfill. Slag that is to be directly disposed is held at the refinery for 7 days, at which time it is transported to a disposal ~
facility. The slag is assumed to be disposed immediately following handling at a sanitary landfill.
The two management options for EAF baghouse dust that are being analyzed in this report are direct disposal in a hazardous landfill and use as an additive in fertilizer. If the dust is to be disposed of, it is transported within 3 days after production. Handling and processing of the dust takes 4 days, at which time the dust is disposed in a hazardous l waste landfill. Electric arc fumace dust that is to be processed as fertilizer is sent to the processor 3 days after production. Processing takes 3 days, and the fertilizer is
[ distributed for use and is used within 1 day.
[
. BOF baghouse dust is disposed of onsite or sent to a sanitary disposal facility after 7 i days. Storage and handiing take 4 days, at which time disposal occurs.
l Post-Disposal:
l
. A sanitary landfill operates for 40 years.
A hazardous landfill operates for 30 years.
. Disposed items are placed in the landfill at the midpoint of the landfill operating period.
Post-closure monitoring oflandfills is done for 30 years.
l
- A disposal site is available for potential residential use after post-closure monitoring j ends. l
( i l
l O 4-93 Draft NUREG 1640, Vol. I 1
I i
Recycle and Disposal of Steel Section 4
]
4.8.4 Dose Evaluation Values for radionuclide-dependent parameters (e.g., A,, DF,,,,) are taken from Federal Guidance Report 11 (EPA 1988) and are tabulated in Appendix B. All other parameters are either radionuclide-independent or material-dependent, and are discussed below; values for these parameters are also listed in Appendix B.
4.8.4.1 Input Radionuclide Concentrations from the Material Flow The undecayed radioactivity concentration in the source material, C,, is used as the source material input as the source material input radioactivity concentration for scenario evaluations.
This parameter is radionuclide dependent and is calculated in the material flow modeling. Table B.8 lists the sources for C, as they appear in the mathematical modeling of the material flow (e.g., C,, radioactivity concentration in metal product after the refining process).
4.8.4.2 Exposure Duration The duration of exposure is the time that the ind.ividuals in the exposed group are assumed to spend in the scenario conditions that result in exposure to cleared material. The number of hours of exposure in each scenario is calculated as the product of the parameters tx , (h/d) and ty, (d/y).
Values for both these parameters are tabulated in Appendix B. All scenarios incorporate uncertainty via the parameter for hours per day,x t ,, and the parameter y t ,(d/y)is fixed. The work-related scenarios use a fixed value of 250 d/y for t y,, and all other scenarios use a fixed value of 350 d/y.
Work related Scenarios !
The maximum number of hours in a typical work year was limited to the fraction of time that a worker would reasonably spend performing the work that would result in exposure to cleared material during a calendar year. The fraction is based on the amount of time a worker would be working directly with cleared material plus the time working in the vicinity of the material.
Generic scenarios for industry workers (scrap handling, refinery workers, and manufacturing l
workers) use a range of values that reflects varying operational practices among scrap yards and I refineries. Even though the members of the exposed groups in these scenarios are dedicated to l
handling scrap or refinery products, it is reasonable to assume that any individual would actually !
spend less than a full working day handling material with residual radioactivity. Other activities during a typical day would include checking out equipment, driving equipment back and forth between parking, storage, and handling areas, refueling equipment, waiting for vehicles to load or unload, receiving instructions or plans for work to be done, and performing other duties.
Therefore a range that often does not include the maximum number of hours in a work day was determined to reflect the likelihood of these other activities.
Draft NUREG 1640, Vol.1 4 94 O
1-Section 4 Recycle and Disposalof Steel p The specific handling scenarios incorporate a range involving a much smaller number of hours in
~an average workday. This is reasonable because there is a much smaller volume of material being handled (EAF baghouse dust) as compared to the other worker scenarios.
The single product use scenario that involves workers (" Roadbed construction activities") would involve considerable variability in the daily number of hours spent using and in the vicinity of refinery slag. These workers would likely not spend an entire year constructing roads using refinery slag, because roads are also constructed using materials other than slag (e.g., gravel).
Also, road constmetion is a seasonal activity in many northem areas of the U.S.
An exposure duration for scenarios involving disposal of material with residual radioactivity was determined using the capacity of typical landfills and the amount of material available to be disposed in a geographic area. These two values (capacity and amount of material available) were ratioed, and the material-specific ratio was multiplied by the number of hours in a working year to estimate values for each material ofinterest.-
The basic assumption for the duration of exposure for commercial drivers of trucks carrying cleared material or any of the co-products of refining was that these individuals were employed full-time in a truckingjob. Specific assumptions for the scenarios in this analysis were developed after talking with individuals in the steel transport industry. It is common for these drivers to work up to 50 hcurs per week; this is supported by statistics from the Bureau of Labor Statistics (BLS 1998), which indicate that local truck drivers frequently work'48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or more a week. It was also detemiined that it was reasonable to assume that there are sufficient amounts O of scrap, slag, baghouse dust, and refined steel for some drivers to spend a majority of their time hauling this material (not necessarily all cleared material, however). These drivers would be hauling a single material a maximum of halfof their workdays (i.e., full loads only one-way).
Some drivers may haul one material (e.g., scrap) to a refinery and load their trucks at the refmery with another material (e.g., slag) for a "retum" trip.
A most likely value was determined to be one-half of a 40-hour work week, with a reasonable minimum value incorporating the assumption ofless time for the drivers that do not spend all of
- their time hauling steel industry material. A maximum value was used to represent one-half of a 50-hour work week.
Values for a driver of a vehicle were used to model a taxi driver or other commercial driver (e.g.
small delivery van). A range from one-half to a full work day with no most likely value was used.
Non-worker Scenarios
. Similar to the worker scenarios, the non-worker scenarios incorporate uncertainty into exposure
. duration via the parameter for hours per day, while the value for days per year was held constant.
- Most of the non-worker scenarios involve use of refinery co-products, most commonly refined steel products. Duration times for the generic small object and large object scenarios were b
v 4-95 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 developed to include those individuals who spend a large fraction of their work day or residential time near these objects (e.g., machine tools, office fumiture, and household appliances or furniture). The most likely value for these scenarios is one-half of a typical work day. A range of 2-8 hours per day would cover a variety of potential exposure situations in both residential and occupational settings.
The scenario involving a small object close to the body involves a wide range of exposure duration because of the variety of potential exposure scenarios (e.g., belt buckles, tools). The scenario involving individuals inside a basement (or other concrete structure) could involve occupational or residential settings, and a range was chosen to incorporate both of these settings.
A most likely value was chosen to represent a residential setting; this was also used as the maximum value in the parameter range. Use of a roadway containing refinery slag was assumed to involve regular, short-term use. Values were for a range to represent a commuter using the same route every work day.
For those exposure scenarios that occur in a residential setting (e.g., person inside a basement made with slag) a year's duration consisting of 5600 hours0.0648 days <br />1.556 hours <br />0.00926 weeks <br />0.00213 months <br /> is assumed. For residential landfill scenarios and the atmospheric release scenarios where an individual spends time indoors as well as outdoors, additional exposure duration parameters are needed. The number of hours spent on indoor, outdoor, and dusty activities are represented by ta, ta, and tu, respectively, and are listed in Table B.7. Nominal values for these parameters were based on values in Kennedy and Strenge (1992); distributions for the parameters were subjectively developed, based on professional judgement and the scenario definition.
4.8.4.3 Material Densities Four fixed values were used for the density of waste, p.: 1) For the waste products that are similar to soil (i.e., BOF baghouse dust), a value identical to the nominal value used for p,; 2) For those waste products that are similar to m"al (e.g., scrap metal and refined metal product), a value derived and used for bulk density in :e calculation of the geometry factors for metal products was used; 3) For immobilized EAF dust, a value of 1.36E+6 g/m3 was used (Logan 1993); 4) For the disposal of slag the same density that was used for slag in a pile was used for slag in a landfill.
Three approaches were used to estimate a range for the bulk density of slag as used in various scenarios: industry contacts, appropriate references, and a theoretical approach. The three l approaches result in a range of estimates that differ by a factor of a little over 3x (1.19 g/cm2 - !
3 3.9 g/cm ). Two estimates of bulk density values were needed for use in the scenarios involving j slag pile and roadbed, because the bulk density of slag would be different in the two scenarios. l The information from industry contacts wasjudged to be the best source and was therefore )
emphasized, because it is specific to EAF steelmaking slag and does not depend on the use of )
l assumptions. One literature source (IAEA 1992) does not provide justification for the value l l used, nor does it give detailed information about the type of slag (e.g., furnace source). The 1
! Handbook of Chemistry and Physics (CRC 1992) lists a value for slag bulk density, however it Draft NUREG-1640, Vol.1 4-96 O\
i Section 4 Recycle and Disposal of Steel does not list the type of slag (e.g., steelmaking, pig iron, other industry). The value listed in Lankford et al. (1985) is specific to .steelmaking slag, but does not give information on type of furnace. Finally, a theoretical value was calculated by weighting the percentage of each chemical constituent of EAF slag, then summing and accounting for the void space presumed to be present in bulk slag. Although this approach is specific to EAF slag, it depends on an uncertain assumption for the porosity of the bulk slag.
To estimate values for the bulk density of a slag pile, the information from industry contacts was emphasized. The industry values are generally lower than those obtained from other sources, however it wasjudged that these slag processors would provide a more accurate value for bulk i density of slag in a pile, since that is what they deal with on a daily basis. One possible j explanation for the lower bulk density values from the slag processors is that the slag in their i piles has expanded, due to hydration of free lime or magnesia in the slag (Lankford et al.1985).
A fixed value of 2.0 g/cm) was estimated by first obtaining an average value from the slag 3
processors (1.74 g/cm ), then adjusting it upward because of the literature value of 2.38 g/cm3 (Lankford et al.1985) (a value of 2.0 is a round number that is approximately midway between .
1.74 and 2.38). !
The slag as used in a roadbed would be different in two key respects from the slag in a slag pile:
it would consist primarily of smaller pieces (0-1 in.'), and it would likely be compacted during road construction. The single density value for the smallest size fraction found in a survey of 2
slag processors _was used as the fixed value (2.4 g/cm ). Although this is the highest value s obtained from any of the slag processors, and it is also the maximum value for steelmaking slag in general (Lankford et al.1985), it was used because of the nature of the use of slag in this i scenario (small pieces and highly compacted).
4.8.4.4 Mixing of Clear.ed Material A basic assumption of this analysis is that material that is cleared from a licensee would enter the general commercial sector. Any cleared material or refinery products could therefore be mixed with non-cleared, but otherwise similar material. This likelihood is incorporated into the analysis '
' in three ways: 1) mixing of scrap that does not undergo any melting at a refinery and mixing of scrap that is melted at a refmery; 2) mixing of refmery slag when used as an additive in concrete; and 3) mixing of material that is disposed. These three concepts are discussed in the following subsections. ,
Mixing of Cleared Scrap A " mixing factor" was calculated and is described in Appendix D. The mixing factor is a multiplicative factor that was used to incorporate the mixing of cleared scrap with other, similar scrap. The mixing factor range was used to modify the exposure duration in the scrap handling
' Personal communication M. McKenzie-Carter, SAIC, and Alexander Mill Service. Plymouth, UT, May 14,1996.
i 4-97 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 and scrap disposal scenarios. These scenarios model the direct use of scrap (no melting). Most other scenarios (except as described in next subsections) incorporate mixing by the use of appropriate values for cleared scrap and other scrap in the material flow model.
Dilution of Refinery Slag Used in Basement Construction An explicit dilution factor (DF) is used in the scenario involving use of refinery slag in the manufacture of concrete that is used in the construction of a basement or other building structure.
This is to account for the amount of slag used in the commercial process where slag is blended with other cement ingredients, heated, and results in a cement clinker that can be ground to the required size. Based on information' that was obtained from the cement industry, a triangular distribution for DF from 0.5% to 3% was used, with a most likely value of 1.5%. For this one scenario, the parameter DF is used multiplicatively in Equation 4.55 to modify the radionuclide concentrations.
Mixing of Waste in the Landfill In order to estimate the fraction of a landfill that could consist of waste from disposing of contaminated scrap or byproducts of recycling,1:ndfill mixing factors were calculated for the resident and disposal activities scenarios. To make reasonable estimates, a bounding case for slag was first examined. It was calculated that if all of the slag generated from refining all of the slightly contaminated scrap steel likely to be cleared from an NRC licensed facility were disposed in a single landfill, it would comprise roughly 4% of the capacity of an average-sized sanitary landfill (40,000 m' out of 1 million m) capacity). This bounding analysis is unreasonable by itself, because industry practice and the economics oflandfill disposal make it extremely unlikely that all slag from contaminated scrap recycle would be disposed in a single landfill. However, the unpredictable nature of future scrap cleared practices by an NRC licensed facility and the varying sizes oflandfills must be considered. If the assumption is arbitrarily made that no more than 2% of the slag from scrap recycling were disposed cf at a single landfill, the total amount disposed in a representative facility would be about 0.2% of capacity (2000 m 3).
This value appears to be reasonable, and is consistent with the " reasonable maximum case" contained in Appendix G of EPA (1997a). In evaluating regional dilution of NRC licensee scrap, it is postulated in this reference that 22,500 t (24807 tons) of scrap could be refined at a single reference mill. Using a slag production rate of 15%, this would result in 3,375 t (3721 tons)
(1,688 m') of slag amounting to 0.15% of capacity for an average landfill. The regional distribution of power plants and steel mills makes it unlikely that this rate of refining could be sustained for multiple years. If the total slag from scrap recycling disposed of at a single landfill were twice the " reasonable maximum" l-year value, the result would be 6,750 t (7,442 tons)
(3,375 m3) or 0.31% of capacity.
Based on this rationale, it is unlikely that the amount of slag from refining contaminated steel present in a single landfill would exceed a few thousand cubic meters and is likely to be very
' Personal communication from W. C. Thurber of S.C. & A.
]
Draft NUREG-1640, Vol.1 4-98 {
1 l
l
_ _ _ _ _ _ _ _ l
Section 4 . Recycle and Disposa! of Steel
,, much less. However, the basic assumption behind the resident-on-landfill scenarios is that
]A significant landfill disposal of slag from refining licensee scrap occurs for at least one licensed facility. Therefore, an estimate of 0.2% is used as the per cent of a landfill capacity comprised of ,
slag that is a byproduct of recycling cleared steel scrap.
' Using this rationale, and appropriate partitioning factors for other byproducts, the following landfill mixing fractions were estimated and used in the assessments of scenarios for residents on closed landfills:
l l
' Steel slag: 0.2% oflandfill capacity I Steel scrap: 0.7% oflandfill capacity Baghouse dust: 0.02% oflandfill capacity These values formed the basis to estimate a range for the parameter FW, fraction of the volume of a landfill that is from cleared material. Ranges were developed by using values 50% of the values listed above.
4.8.4.5 Extemal Exposure Parameters The parameter Uc, was used to account for uncertainty in extemal exposure rates. The fixed-value extemal dose factors used in this analysis come from two sources: Federal Guidance Report No.12, and values calculated using the code Monte Carlo N-Particle (MCNP) specifically for this analysis. Federal Guidance Report No.12 values were used in scenarios involving large areas of contaminated soil or similar materials that can be treated as a infinite i . planar source. The MCNP values were used for scenarios where finite objects of shapes and composition were modeled. The Uor is a multiplicative factor based on an evaluation of the l circumstances described in each scenario. A discussion of the calculation of GFs and development of distributions for Ucr are both discussed in Appendix C, as is a listing of the GF l values used. Values for Ucr are tabulated in Appendix B. l
- Shielding factors were also used in this analysis to calculate the external exposure dose factors.
A vehicle shielding factor, SF, was used in the disposal activity scenarios to account for the L
likely shielding afforded by the large equipment used at landfills (e.g., loaders and bulldozers).
Based on interviews with equipment manufacturers and landfill operators, a geometric model was developed to characterize the effective shielding for operators of this type oflarge l equipment. Transmission factors were developed sufficiently to determine a reasonable triangular distribution from 0.3 to 0.7, with a most likely value of 0.5. These values were used multiplicatively to reduce the external exposure dose factors for workers handling waste at landfills.
. Shielding factors were also used for the types of activities in residential scenarios. Values 'for the parameters SFI and SFO were developed from the values used in Kennedy and Strenge (1992) because they represented reasonable values for a generic member of the public.
m 4-99 Draft NUREG-1640, Vol.1
R: cycle and Disposal of Steel Section 4 The extemal exposure pathway in the atmospheric release scenario uses a parameter for the period oflong-term buildup for activity in soil, to. A fixed value of 5.48E+3 d is used for this parameter and was taken from NRC Regulatory Guide 1.109 (NRC 1977).
4.8.4.6 inhalation Exposure Parameters This section presents a description of the basis for parameter values for those radionuclide-independent parameters used in the calculation ofinhalation exposure, including those that address mass loading, and breathing rate.
Breathing Rate Two methods used to estimate breathing rates for dose assessments are the tidal volume and frequency method (ICRP 1974, ICRP 1994, and EPA 1989a) and the method using oxygen demand based on metabolic conversion of food nutrients (Layton 1993). Although the latter method is takes into account variations in oxygen uptake efficiency, lung physiology, and metabolic efficiency among individuals, it is not as widely accepted as the tidal volume method.
Both the EPA and the ICRP base their average hourly breathing rates on the tidal volume (ml/ breath) and the frequency (breaths / minute) for various activity levels, and that is the method adopted for this study.
l The inhalation rates for different levels of activities in ICRP (1994) and EPA (1989a) were reviewed to determine a reasonable range to use for breathing rate in the scenarios in this analysis. Both reports are based on tidal volume (ml/ breath) and frequency (breaths / min). The EPA listing is detailed and allows more interpretation of the values, and was judged to be more !
representative of workers and members of the public. Therefore, the EPA values were emphasized. Furthermore, the values for males were used because it is more likely that the jobs described in the exposure scenarios would be performed by males. The range for breathing rate given in EPA (1989a) is from 0.7 m'/h during resting to 5.1 m'/h for very heavy activity. The range in ICRP (1994) is from 0.45 m'/h for resting to 3.0 m)/h for heavy exercise. From these ranges, two triangular distributions were developed, one for outdoor activities and the other for indoor activities. The range used for outdoor activities is from 0.6 m'/h to 3.0 m'/h, and the !
range for indoor activities is 0.5 m3 /h to 1.2 m'/h. Both distributions use a most likely value of 1.2 m'/h, consistent with Volume 1 of NUREG/CR 5512 (Kennedy and Strenge 1992) and some of the scenarios va'ues in Volume 3 of NUREG/CR-5512 (Beyeler et al,1996).
Respirator Use j
Only one work-related scenario, refinery baghouse operations, presents hazards that would typically require a worker to wear a respirator. In the refinery work environment, the inside of a baghouse represents a hazardous environment. The presence of airborne baghouse dust in a confined and congested area requires that precautions be taken; typically including protective clothing and a respirator. Therefore, in order to be realistic, use of a respirator is assumed.
Draft NUREG-1640, Vol.1 4-100 O
w.
Section 4 Recycle and Disposal of Steel n ' ' Based on conversations with industry representatives'm and the fact that there are regulations
- requiring the use of respiratory protection while working in dusty and hazardous environments, a worker entering the baghouse without a respirator is not considered realistic and, therefore, is not considered. Requirements stated in 42CFR84 list minimum efficiencies for three levels of respirators (95%,99%, and 99.97%). According to Caesar 8respirators in the steel recycle industry are selected and approved by management based on the physical and chemical properties of the ' air contaminants that will be encountered and the concentration level likely to be encountered by an employee. However, there are no reliable data on which to base a range, and it was judged that a range biased toward the lower end of efficiencies would be most likely.
In order to account for use ofless efficient respirators, as well as ill-fitting respirators, a range of 90% to 99.7% was used for respirator efficiency.
Mass Leading and Respirable Fraction The mass loading (ML) factor used for the inhalation exposure pathway calculation is difficult to estimate. The usual approach to estimating intake via mass loading models assumes that the concentration of radioactivity in airborne particulates is the same as in the material from which those particulates are generated. In this case, airborne radioactivity is assumed to be associated exclusively with particulates originating from the scrap material or recycle product regardless of s any other sources of particulates at thejob site. For the scenarios that include the inhalation pathway, the mass loading factor used for the inhalation exposure pathway calculation must be i typical of dusty work environments like that which would be found around a construction site. '
The mass loading factor approach was used so that the concentration of radionuclides in the dust O could be directly related to an air concentration by use of an assumed mass of dust particulates in the air at the receptor location. A mass loading factor is typically used in environmental evaluations to relate soil concentrations to air concentrations' Although recycle scenarios are not l
strictly an environmental setting, and the dust volume is not in situ soil, the use of a mass loading !
approach is valid because it relates the source radioactivity concentration to an air radioactivity concentration using an appropriate value for dust loading.
The respirable fraction of resuspended material is another key parameter for the inhalation pathway. Fugitive emissions from the steel industry include open dust sources such as raw material storage piles from which emissions are generated by the forces of wind and machinery acting on exposed aggregate materials. The EPA has sponsored the Midwest Research Institute to measure particulate emissions and particle size distributions from a variety of sources including unpaved roads of mixed slag and soil in the vicinity of steel mill slag piles (Cowherd et al.1979). Measurements include mass loading near areas disturbed by vehicular traffic and in undisturbed upwind areas.
' Personal communication, M. Anderson, SAIC, with Vinnie Caesar, Midwesco Filter Resources, Inc., Oct.1996.
2 Personal Communication, S. Jones, SAID, with Bill Fergeson, Arkansas Steel, May 9,1996.
' Personal Communication, S. Jones, SAID, with Many Morelac, Border Steel. April 26,1996.
' Personal Communication, S. Jones, SAID, with Al Pulliam, Bayou Steel, April 25,1996.
4-101 Draft NUREG-1640, Vol. I
Recycle and Disposalcf Steel Section 4 The gross values presented in Cowherd et al. (1979, Table 3-4) were used to estimate mass l loading and respirable fraction (data from roads treated fc,r dust suppression were not included; values for profiler samplers, cascade impactors and hi-vol samplers (5m) were pooled). The summary statistics for these values are as follows. l 1
n = 35, range = 2.1 mg/m3 to 13.6 mg/m2 , mean stnd. dev.= 7.0
- 3.2 mg/m'.
In addition, upwind background measurements were reported for representing undisturbed areas l in the same vicinity. Values in Cowherd et al. (1979, Tables 3-4 and 3-14) were used to estimate background levels of particulates. The summary statistics for these values are as follows:
n = 13, range = 0.43 mg/m 3 to 1.2 mg/m2 , mean
- stnd. dev.= 0.79 0.23 mg/m2 .
Based on the information presented here and in Cowherd et al. (1979) a triangular distribution between 1.3 mg/m' and 7.4 mg/m), and a mode of 3.9 mg/m 3was calculated and used for the I mass loading factor for dusty work-related scenarios (i.e., slag worker, scrap handling, dust handling, refinery product handling, road construction scenarios, and disposal activities with j BOF dust and slag). This was calculated by incorporating an assumption that an individual i spends one-half of the time upwind (.79 mg/m') and one-halfin a high concentration area (7 mg/m)).
Cowherd et al. (1979) also contains estimates of the mass median diameter, the fraction less than 30 pm, the fraction less than 5 pm, and the fraction greater than 50 pm. Linear interpolation between the fractions less than 30 pm and less than 5 pm was used here to estimate the fraction less than 10 pm. Respirable particles are considered to be less than 10 pm. From the summary statistics for these interpolated values listed below, a triangular distribution between 0.23 and 0.42 was med, with a mode of 0.33 was used for the respirable fraction, RF, when it is applied to resuspended slag.
n = 8, range = 0.23 to 0.42, mean
- sind. dev.= 0.33
- 0.07.
One special case scenario (refinery baghouse operations) occurs in an extremely dusty environment. Mass loading inside a baghouse is apparently not a commonly measured value, and inquiries to steel refineries did not result in locating any measured values. Some data are available, however, to support an estimation of this parameter value, i.e., rneasurements of the respirable fraction of dust; this was used to estimate the mass loading parameter value. The mass loading factor approach was used so that the concentration of radionuclides in the dust could be directly related to an air concentration by use of an assumed mass of dust particulates in the air inside the baghouse. A mass loading factor is typically used in environmental evaluations to relate soil concentrations to air concentrations. Although a baghouse is not strictly an environmental setting, and the dust volume is not in situ soil, the use of a mass loading approach is valid because it relates the dust source radioactivity concentration to an air radioactivity concentration using an appropriate value for dust loading. Background levels of dust can be estimated from environmental settings, where ambient air concentrations of dust particulates can range up to 254 pg/m3 in urban locations, and up to 79 pg/m3 in nonurban locations 3
(Healy 1980). A value of 100 pg/m is often used for predictive purposes (e.g., Anspaugh et Draft NUREG-1640, Vol. I 4-102
L l l
Section 4 Recycle and Disposil of Steel al.1974), the EPA has used 100 pg/m2for screening calculations (EPA 1977), and often a value 2
( of 200 pg/m is recommended for generic evaluations for sites that may include some mechanical ;
disturbance (Healy 1980). l l
The basic approach used to estimate the mass loading and respirable fraction of dust for the I baghouse worier was based on a limited amount ofindustry knowledge, measured data for respirable fraction of dust, and regulatory limits. The industry knowledge consists of an understanding that a steel refinery generates a large amount of dust [on the order of 15 kg dust per metric ton of steel pmduced, which is equivalent to several thousand metric tons per year for I a typical steel refinery (EPRI 1993)], and therefore a large mass of dust must pass through a refinery baghouse. '
Applicable data are presented in Jeffery and Vay (1986), which provides particle size data for emissions from EAF, BOF, and other processes. They cite a value of 0.58 for the mass fraction less than 10 pm from melting and refining carbon steel in an EAF. Szabo and Gerstle (1978) provides particle size data for particulate emissions from EAF and BOF processes, citing a value of 0.70 for the mass fraction less than 12 pm and 0.61 for the fraction less than 8 m.
In addition, Cass and Langley (1977) provides data from a controlled experiment that measured dust characteristics from an EAF refining carbon steel. Measurements included particle size and mass at both the inlet and outlet of a baghouse. Ten separate experiments were run. The mass fraction less than 10 pm varied from a minimum of about 0.40 to a maximum of about 0.70 with a mean of about 0.60. These values are approximate because they were interpolated from graphs.
V Finally, the regulatory information considered consists of an occupational Safety and Health Administration (OSHA) limit for the Permissible Exposure Limit for total suspended particulates at a work environment: the 8-hour time-weighted-average value for total dust allowed by OSHA is 15,000 pg/m3 , and the allowed respirable fraction is 5,000 pg/m3 (NIOSH 1990). This suggests an implied RF value of 0.33.
From these sources, a triangular distribution between 1 mg/m2 and 15 mg/m 2was used for mass loading in a baghouse, with a rnode of 10 mg/m2 . Likewise a triangular distribution was used for respirable fraction in this scenario, with a range of 0.4 to 0.7, and a mode of 0.6. This distribution was also used for scenarios involving handling EAF or BOF baghouse dust.
To put these estimates in context, they can be compared to values used in similar analyses. The range derived for use in this analysis for airborne dust concentration is within the range of 0.1 mg/m' to 40 mg/m3used in previous similar analyses (e.g., fixed value of 0.1 mg/m3 used in IAEA [1992]; fixed value of 5 mg/m 3used in O'Donnell et al. (1978]; fixed value of 40 mg/m2 used in EPA [1997]).
v 4-103 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 Soil Suspension l
Seven additional parameters are needed to model the suspension of soil for the residential l scenarios. The mass loading values for indoor, outdoor, and dusty activities (i.e., ML,,,, ML , )
MLoo,,) as well as the indoor dust-loading on floors, Po, and the indoor resuspension factor, RF,, !
are taken from Kennedy and Strenge (1992). For refinery atmospheric release scenarios, when j the plume passes over a house or building, only a fraction of the material in the plume enters the l building, and is therefore respirable by the resident. Yu et al. (1993) estimated that the dust level {
inside a building is about 40% of that outdoors. Because conditions within a plume are similar to those with suspended soil, a value of 0.40 is used for the indoor fraction of outdoor radioactivity concentration, RFI.
For atmospheric release scenarios, the thickness of the soil layer that is available for suspension, {
RL, determines the amount of radioactivity that is suspended from the surface. The types of !
activities that could cause suspension are walking or driving on packed dirt or roadways. A l value of I cm (0.01 m) is used for RL, based on the assumption that the particles that are j deposited on the soil during an atmospheric release would not be mixed into the soil under l normal conditions.
4.8.4.7 Inadvertent Secondary ingestion Exposure Parameters )
l It is reasonable to include the secondary ingestion exposure pathway for all scenarios where i inhalation exposure is assumed, because of the presence of dust in an industrial environment. If there is a resuspension of dust that is available for inhalation, then it is reasonable to assume that inadvertent secondary ingestion can also occur. The range used for the secondary ingestion, IR, of surface deposited material (e.g., slag, dust, or metal shavings) is based primarily on the review of surface-contamination ingestion data and soil ingestion rates contained in Volume 1 of NUREG/CR-5512 (Kennedy and Strenge 1992). The overall range cited in NUREG/CR-5512 for secondary soil ingestion is from 0 mg/d to 200 mg/d. These values were interpreted to be based on a variable number of hours per day, based on the assumed source of data (e.g.,8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for worker data, longer for resident data). From these data, a uniform distribution over the range of 2.1 mg/h-30 mg/h was used in this analysis. The upper-end value wa selected following discussions with EPA contractors regarding consistency with the analyses being conducted for the EPA (EPA 1997a).
{
4.8.4.8 Drinking Water Ingestion Exposure Parameters j Radionuclide-independent parameters used in the evaluation of the drinking water exposure pathway include those that model the transport of radionuclides to the groundwater as well as human consumption. All the scenarios that include the drinking water ingestion exposure pathway assume that box 2 (unsaturated layer) and box 3 (aquifer) are initially free of contamination. Therefore, A 3 03 and Am are set equal to zero.
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l
Section 4 - Recycle and Disposal of Steel For several parameters used in the drinking water ingestion exposure pathway, it was determined O that the values used in Kennedy and Strenge (1992) were appropriate for use as point estimates or estimates of central tendency for the drinking water exposure dose factor analysis (see Appendix B for values used). The parameters T i (time period for infiltration and irrigation) and T,(time period for pumping) were both fixed at the values used in Volume 1 of NUREG/CR-5512 (Kennedy and Strenge 1992). The Volume i NUREG/CR values for porosity, ni and n2, and saturation ratios, fi and f 2, were used as most likely values in triangular distributions. The
. Volume 1 NUREG/CR values for A, (area ofland under cultivation) and I (infiltration rate) were used as the geometric means oflognormal distributions.
For the parameter U., analysis of survey data has shown that tap water averages about 60% of total water consumption (Roseberry and Burmaster 1992). These data support a lognormal distribution of total tap water consumption having a geometric mean of 0.957 L/d and a l geometric standard deviation of 1.77. In addition, not all tap water consumption comes from i one's own tap. A significant numbers of meals can be eaten outside one's home, for example.
The data on the fraction of tap water from one's own tap are poor and are best represented by a uniform distribution having a minimum of a 0.5 and a maximum of 1.0. A Monte Carlo calculation of the product of the two parameters yields the value of 0.71 L/d used in this analysis foi tap water consumption.
i Kennedy and Strenge (1992) made the assumption that the amount of water needed for domestic purposes was for one person. Because the areas of the landfills in this analysis are so large, it is
)
]
likely that more than one person would be living on the land over a closed landfill. Therefore, for this analysis, the geometric mean for the amount of water used for domestic purposes, Vu J
\ and V&, is based on 10 people,9.1E+5 L. The amount of water from the aquifer needed for irrigation is determined based on the average irrigation rate of 2.08 L/m2 -d, the area ofland under cultivation,2500 m ,2 and 365 d/y (Kennedy and Strenge 1992). Therefore a value of 1.9E+6 L was used as the basis for a distribution for Vi , (volume of water used for irrigation purposes 1 annually). A beta distribution was used for V,i to be consistent with the distribution assumption !
for this parameter in Volume 3 of NUREG/CR-5512 (Beyeler et al.1996). ]
Slag Pile at the Refinery The size of the slag pile in the slag storage scenario affects the modeled concentration of radionuclides in the aquifer, and thus the drinking water dose. The size of the slag pile used is 20,000 t (22,050 tons), corresponding to a slag pile comprised of the annual amount produced at a typical steel refinery. This value is consistent with EPA (1997), and wasjudged to be a reasonable slag pile size to use for this scenario. This value seems reasonable because slag is typically stored to " cure" for 6 months or longer, and also because slag producers often keep
. large stockpiles to be able to participate in bids for projects seeking to purchase large amounts of slag (Kalyoncu 19%). The slag pile is modeled as a half-cylinder with a radius of 4 m (13 ft) and a length of 400 m (1,312 ft), resulting in a large rectangular base with the dimensions of 8 m (26 ft) wide by 400 m (1,312 ft) in length, and an area of 3.20E+3 m). The thickness of box 1 is assumed to be the height of the slag pile,4.0 m. This results in a total volume of 1.0E+4 m' of slag being stored, and assuming the density of slag in a pile is 2.0E+6 g/m), the most likely value for the total mass of slag present is 2.0+10 g (20,000 t [22,050 tons]). A value for the geometric 4-105 Drah NUREG-1640, Vol. I
1 Section 4 l RIcycle and Disposal of Steel mean for the thickness of box 2 in the drinking water model, from the bottom of the slag pile to the top of the aquifer, was obtained as the sum of the thicknesses of box 1 and box 2 in NUREG/CR-5512,1.1 m (3.77.ft)(Kennedy and Strenge 1992). This is reasonable because, similar to the modeling done in NUREG/CR-5512, this scenario is intended to be generic for sites across the United States.
As described in the preceding paragraph, the size of the slag pile is based on a 1-year production I of slag. Therefore, a 1-year delay period following clearance was incorporated into the !
modeling, and the drinking water dose over the 1-year period from 1 to 2 years following clearance was calculated for this scenario. As described earlier in Section 4, the TDS of the aquifer in the slag storage scenario was calculated over a long period of time. It was verified that based on these models, the aquifer remained potable during this period.
4.8.4.9 Ingestion Exposure Parameters This section presents a description of uncertain values for those radionuclide-independent parameters used in the calculation ofingestien exposure. Values for most environmental and biotic transport of radionuclides and subsequent human consumption parameters were fixed and were taken from Volume 1 of NUREG/CR-5512 (Kennedy and Strenge 1992). These values were reviewed and were deemed appropriate and reasonable for the scenarios presented in this report.
Uncertainty in the food ingestion pathway was incorporated via the parameter for the fraction of an individual's annual diet derived from a home-grown garden. Two types ofingestion exposure pathways are calculated; irrigation and non-irrigation. Although a dose is calculated separately for each of these models, the same distribution ofinput values for the fraction of annual diet (DIET) from each of the types of food (irrigated and non-irrigated) was used. The most likely setting for the scenarios in this analysis were judged to be that of an urban or suburban garden supplying a relatively small fraction of dietary fresh vegetables on a seasonal basis. The triangular distribution used in this analysis for DIET (0-0.25, mode of 0.08) corresponds to the generic assessment scenario for an urban gardener in EPA's CAP-88 code (EPA 1991).
The soil ingestion pathway also includes uncertainty, incorporated in the modeling via the parameter for consumption rate of soil, Uo. The range used is based on an extensive recent review of human soil ingestion (Simon 1998). The lognormal distribution used in this analysis is adopted from Simon (1998), for " suburban lifestyles (with homes)-including lawns, parks, recreational areas, some gardens."
The atmospheric release scenario requires the use of the thickness of box 1 (surface layer) for the ingestion exposure pathway. This parameter is used to calculate the radioactivity concentration in the soil from deposition, assuming complete mixing throughout box 1. The tixed value used for this parameter for the atmospheric scenario is the assumed depth of a plow layer,0.15 m.
Draft NUREG-1640, Vol. I 4-106 O
Section 4 Recycle and Disposal of Steel The transport of C-14 from atmospheric release to uptake into plant depends on a fractional equilibrium ration, p,.n. According to Regulatory Guide 1.109, this ratio is set equal to 1.0 for a
.( continuous release. Therefore, a value of 1.0 is used for p,.n. The transport of H-3 from atmospheric release to uptake into plants depends on the absolute humidity of the atmosphere at the receptor, H. Till and Meyer (1983) states that atmospheric humidity varies greatly from one location to another in the United States. A graph in Till and Meyer (1983) shows that the j absolute humidity ranges from an average of 4.9 g/m3 in the west (e.g., Idaho, Utah) to an l average of 13.8 g/m3 in the southeast (e.g., Florida). A most likely value (mode) of 7 g/m3 for.
the absolute humidity was calculated by incorporating the approximate percentage of the 4 continental U.S. that had a particular average humidity, as shown in Till and Meyer (1983, Figure 9.1). The following assumptions were used to calculate a weighted average absolute humidity, H, of 7 g/m3.
Average absolute Percentage of U.S. humidity (g/m8) 40% 4.9 20% 6.6 20% 8.4 15 % 10.7 5% 13.8 Overall Weighted Average 7.3 An overall range of 3 g/m3 to 16 g/m was 3 used based on the values in Till and Meyer (1983).
4.8.4.10 Atmospheric Release Parameters The total mass of dust that is calculated to escape a refinery baghouse in a year, Mm is calculated using the material flow model. The duration of release of refinery atmospheric effluent, is 1 year, in order to calculate an annual average release rate.
The uncertainty in the atmospheric dispersion calculations was incorporated via the parameter Chi /Q, the annual average dispersion factor. Historical data and statistical summaries for approximately 300 weather stations in the U.S. were obtained (Doty and Wallace 1976), and used to conduct a Monte Carlo analysis on the Gaussian plume dispersion equation. The median of the resulting output (3.76 E-06 s/m )3 was obtained and used as the geometric mean of a lognormal distribution, and an input distribution was fitted to the high end of the Monte Carlo distribution using a geometric standard deviation of 2.59.
' The fraction of time during a year that each stability class occurs is taken from Doty and Wallace (1976). The average windspeed for stability classes A-F is calculated from data in Till and Meyer (1983, Table 2.1). In calculating average windspeeds, the lowest and highest windspeed O 4-107 Draft NUREG-1640, Vol. I
1 Recycle and Disposal of Steel Section 4 l
categories were not used (< 2 m/s and > 6 m/s), and the resulting average windspeeds are !
representative of typical windspeeds. A value of 1.0 is used for the average windspeed for j stability class G.
l, The effective height of the refinery stack, H, is assumed to be 40 m (131 ft) above the ground.
This value is reasonable for refineries, based on the physical height of typical baghouses, the effluent velocity, and the temperature of the effluent. Because the distance from the refinery to the nearest receptor, x, is generic, and a typical resident is assumed (suburban garden) a fixed distance of 1,000 m (3,280 ft) is assumed.
The atmospheric scenario also uses a total deposition velocity, Vo(T) for calculating external exposure from ground deposition (Equation 4.25) and internal dose from foliar deposition on plants (Equation 4.27). The value for this parameter is dependent on the type of element, so the radionuclides are grouped into three general groups: iodines, gases, and particulates (all others).
The distributions used were developed using data and information in standard references (e.g.,
Miller 1984; Till and Meyer 1983) for deposition velocity and interception fractions.
4.8.4.11 L'andfill Parameters For the scenarios involving a resident on a landfill after closure, the total mass of contaminated material in the landfill, QT, is needed. This parameter is used to calculate the radioactivity concentration in the soil, assuming complete mixing. This mass includes the daily and final cover soil, and/or waste, depending on the type of waste. The total mass of material in a landfill was calculated using the following information for sanitary and hazardous waste landfills:
Sanitary Landfill Assumptions
. The depth of an average sanitary landfill unit is about 4 m (13 ft), using the average capacity (waste and daily cover soil) of 1.4E+6 m 3and an average area of 3.4E+5 m 2 (Dehmel et al.1994).
. The ratio of waste to daily cover soil is 4:1 (Dehmel et al.1994), which results in an average of 80% (1.1E+6 m3 ) of the capacity of the landfill consisting of waste, V and the remaining 20% (2.8E+5 m3 ) consisting of daily cover soil.
{
i
. EPA recommends that the final closure cover on a sanitary landfill consist of at least 0.46 m (1.5 ft) of soil for an infiltration layer and 0.15 m (0.5 ft) for an erosion layer, resulting in a total cover of 0.61 m (2 ft) (EPA 1993b). Therefore, the total volume of final cover soil on a sanitary landfill is 2.1 E+5 m 3.
- The bulk densities of the wastes (as disposed) are as follows: BOF baghouse dust 1.6E+6 g/m3 , refinery slag 2.0E+6 g/m 3, and metal 3.93E+6 g/m3.
Draft NUREG-1640, Vol. I 4-108 O
l l
Section 4 Recycle and Disposal of Steel i .
The radioactivity in the waste types that are similar to soil (i.e., BOF baghouse dust and O refinery slag) are dispersed throughout the total mass (waste, daily cover soil, and final U cover soil). However, for wastes that are similar to metals the radioactivity is dispersed only throughout the daily cover soil and final cover soil.
+
For BOF baghouse dust disposal scenarios, the total volume of material in a sanitary landfill after closure is 1.6E+6 m2 (waste = 1.1E+6 m), daily and final cover soil =
4.9E+5 m2 ). Assuming a value of 1.60E+6 g/m3 for the density of soil as well as for disposed BOF baghouse dust (EPA 1993a) a value of 2.54E+12 g is calculated for QT.
For slag disposal scenarios, the total volume of waste in a sanitary landfill is 1.1E+6 m) while the total volume of soil in the landfill (daily and final cover soil) is 4.8E+5 m*.
Assuming a density of 1.60E+6g/m3 for soil and 2.0E+6g/m3 for slag, a value of 2.97E+12 g is used for QT.
For scenarios involving the disposal of metal wastes, only the volume of soil (daily and final cover) is needed to calculate QT. Assuming 1.60E+6 g/m2 for the density of soil, a value of 7.8E+11 g is calculated for QT.
In order to account for the small fraction of a landfill that would likely consist of material derived from cleared scrap, a sanitary landfill dilution factor was calculated and discussed above (see Section 4.8.4.4). For estimates of the percent of a landfill that would be comprised of material derived from licensee scrap, the following dilution factors were
[ i applied to each waste category: Scrap metal (0.7%), slag (0.2%), baghouse dust (0.02%),
V and refined metal products (0.6%).
l l
Hazardous Landfill Assumptions a Based on landfill survey information in Dehmel et al. (1994), the depth, area, and l capacity of an average hazardous landfill unit are 8.6 m (28 ft),7.28E+4 m2 , and l
6.58E+5 m), respectively.
- Based on information in EPRI (1993), a maximum of approximately 25% of the capacity I of a hazardous landfill would consist of contaminated EAF dust. This results in 1.65E+5 l m' of EAF dust and 4.94E+5 m) of daily cover soil and other waste.
. For hazardous landfills EPA recommends that a minimum depth of 1.5 m (5 ft) of cover material be in place upon closure (EPA 1989b). Therefore, the total volume of final cover soil on a hazardous landfill is 1.09E+5 m).
. The radioactivity in disposed EAF dust is assumed to be dispersed throughout the total volume of material in the landfill (waste and soil).
l l
l m
l v 1
l 4-109 Draft NUREG-1640, Vol. I
l i
l Recycle and Disposal of Steel Section 4 l
The total volume of material in a hazardous landfill after closure (waste, daily cover soil, and final cover soil) is 7.68E+5 mS . Assuming a density of 1.60E+6 g/m3 (EPA 1993a) for the soil (daily and fmal cover), and a density of 1.36E+6 g/m3 for the EAF dust, total mass of material in a hazardous landfill, QT, is 1.19E+12 g.
The thickness of box 1 (surface layer) in the landfill model, H i, is the sum of the depths of the landfill and the final cover soil. Using a depth for an average sanitary landfill of 3.66 m (12 ft)
(Dehmel et al.1994) and a final closure cover depth of 24 inches (0.61 m), the thickness of box 1 for a sanitary landfill is 4.27 m (4 ft). According to Dehmel et al. the depth of an average hazardous landfill is 8.6 m (28 ft)(Dehmel et al.1994). For hazardous landfills EPA recommends that a minimum depth of 1.5 m (4.9 ft) of cover material upon closure (EPA 1989b). Therefore, the total thickness for hazardous landfills is 10.1 m (33 ft).
As seen in the mathematical modeling for the resident on closed landfills, the leach rate )
parameter Lu is not used for metal waste (e.g., scrap metal or refined metal product). Therefore, j the thickness of box 1 is not needed for these scenarios. The leach rate constant for the i movement of radionuclides from disposed metal to the surrounding soil is dependent on the {
corrosion of the metal. The leach rate constant used for the movement of radionuclides from the metal waste to the soil, L,, is 4.17E-4/y (1.14E-6/d) (Maheras et al.1994).
The thickness of box 2 (unsaturated zone), H2 , is the distance from the bottom edge of the landfill '
to the top of the water table (aquifer). A mean value of 27 m (87 ft) was used for sanitary landfills and 14.9 m (49 ft) for hazardous landfills for this distance (Dehmel et al.1994).
The radionuclides in the waste placed in sanitary landfills are assumed to begin leaching immediately upon placement in the landfill. The time between beginning ofleaching and the time radioactivity concentrations in groundwater are determined is treated as a probabilistic parameter. The distribution of times is based on what is realistic for the exposed group and the exposure situation addressed y aach scenario.
For the sanitary landfill resident scenarios, leaching is assumed to begin immediately upon disposal of the cleared material, i.e., at the "beginning" of the scenario. Groundwater activity is determined between 50 y and 150 y after leaching begins (18,263-54,788 d). These times are based on professional judgement. The objective was to use a reasonable time frame, without being overly conservative. It was judged unreasonable to assume immediate residence on an abandoned sanitary landfill, yet it is also unreasonable to assume time frames far into the future.
For the sanitary landfill resident scenarios, the use of a uniform distribution for the time between beginning ofleaching and the time radioactivity concentraions in groundwater are determined (between 50 y and 150 y after leaching begins) means that the 100-year range of time that is used to calculate groundwater radioactivity concentration corresponds to the 100 years immediately following the end of the post-closure monitoring period. This is because of the remaining 20 years oflandfill operational,(one half of the 40-year total), followed by a 30-year monitoring period.
Draft NUREG-1640, Vol. I 4-110 O
a, Secti:n 4 - Recycle and Disposal of Steel I
p For the hazardous landfill resident scenario (for EAF dust), leaching is assumed to begin at the l end of the post-closure monitoring period, approximately 45 years after clearance (following 15 l
_ years oflandfill operation and 30 years of post-closure monitoring). The time frame for '
. groundwater activity determination, between 50 y and 100 y after leaching begins
- (18,263-36,525 days), corresponds to the time period between 95 y and 145 y after clearance.
- 4.8.5 Steel Surface to-Mass Ratio The surface-to-mass ratios for various steel objects were evaluated to develop an appropriate range to use for this study. For this analysis, steel objects are assumed to have a density of 7.8 g/cm'. Using this density, theoretical values for the surface-to-mass ratios for various objects vary over a wide range from approximately 0.01 cm2 /8for large spheres (30-cm radius) and bar stock (10-cm radius), up to approximately 2.0 cm 2/g for small bar stock, pipes, and sheets.
Data are not available provide an adequate basis for choosing a "best estimate" from this range of .
values. Using professionaljudgement and these theoretical data, the value of the surface-to-mass ratio for recycled steel scrap is best described by a loguniform distribution having a minimum of 0.1 cm2 /g and a maximum of 2.0 cm2 /g. The minimum value is characteristic of bar stock having a radius of 1.0 cm. The maximum value is characteristic of pipes and sheets having a thickness of 0.05 cm. These values are representative of bar stock, pipes, and sheets of various sizes with residual radioactivity on one side only. A wide variety of steel objects commonly found at nuclear facilities have surface-to-mass values that fall within this range.
This range can be compared to other estimates for studies similar to this one. The EPA Technical Support Document (EPA 1997) contains an estimated average surface-to-mass ratio of 0.3 cm2 /g for all potentially cleared steel from NRC licensed facilities and the DOE complex.
O'Donnell et al. (1978) suggested a value of 0.14 cm 2/g as representative of typical heavy sheet steel, and O'Donnell's calculations are based on a reference steel object with a surface-to-mass ratio of 0.45cm 2/g.
4.9 Dose Factors for. Recycle of Steel Scrap This analysis of recycle of cleared steel scrap includes 27 separate scenarios evaluated for 85 radionuclides. Of these,9 scenarios have the highest dose factor for at least one radionuclide.
Table 4.10 lists the mass-based critical-group dose factors for each radionuclide. Table 4.11 lists the corresponding derived surficial critical-group dose factor for each radionuclide. Results for all 27 scenarios are tabulated in Appendix A.
The mean values of the critical-group dose factors for each radionuclide are listed in Table 4.10.
These represent the dose to the average member of the critical group exposed to radioactivity distributed throughout the mass of cleared steel (Bq/g emCi/g). The circumstances of that exposure are described by the scenario indicated in the right hand column. The 5*,50*, and 95*
percentiles listed for each radionuclide represent the underlying distribution of dose factors calculated for each critical group. The range of values from the 5* to the 95'h percentile is the 4-111 Draft NUREG-1640, Vol.1
I l
Recycle and Disposal of Steel Section 4 90% confidence interval on the dose factor. That is, there is a 90% certainty that the dose factor for the average member of the critical group lies within this interval. The confidence interval is a subjective measure of uncertainty in the dose factor that includes estimates of the variability and uncertainty in the parameters used in each scenario.
The ratio of the 95* to the 5* percentile is a useful measure of the relative width of the 90%
confidence interval for comparison between scenarios. Smaller values of the 95/5 ratio indicate less uncertainty than larger values. The scenarios with the smallest uncertainty are those with the fewest number of exposure pathways and the least uncertainty in the parameters describing those pathways. Of the nine critical group scenarios listed in Table 4.10, the scrap transportation scenario has the smallest uncertainty with a 95/5 ratio of about 2 for most radionuclides. This scenario involves only the external dose pathway. It includes uncertainty only in the time of exposure for the truck driver, the external dose rate factor for the cargo of scrap, and the timing of the scenario. The uncertainty in the timing of the scenario is unimportant for most radionuclides. For a few radionuclides with very short half-lives uncenainty in the timing of the scenario contributes some what to the width of the confidence interval. For example, Re-186 4 with a 3.8 day half-life has a 95/5 ratio of about 3.
For all scenarios that take place subsequent to the initial transport of scrap, additional sources of uncertainty are introduced and wider confidence intervals result. Scenarios that address handling of scrap include uncertainty due to dilution with other scrap. They also include additional j exposure pathways-inhalation of resuspended dust and inadvertent ingestion under dusty l conditions. Scenarios that address handling and processing of refinery products such as !
baghouse dust and refinery slag include additional uncertainty in how much of each radionuclide {
is partitioned to these materials. This group of handling and processing scenarios have 95/5 ratios that range from about 10 to about 50. The relative contribution to this uncertainty from scenario timing, radioactivity partitioning, and internal dose pathways is nuclide-dependent. The unce tainty in these dose factors results from a complicated interaction of half-life, radioactive decay properties, and chemical behavior as well as uncertainties in describing the circumstances under which individuals are exposed.
Greater uncertainty is associated with scenarios that involve multiple exposure pathways and complex submodels. The atmospheric release scenarios, for example, include an atmospheric dispersion model and pathways for ingestion, inhalation, and extemal exposure. Dose factors for nuclides limited by the atmospheric release scenario have 95/5 ratios that range from about 60 to slightly over 200. Most of this uncertainty is due to the atmospheric dispersion model but additional contributions from partitioning to refinery off-gas and uncertainties in ingestion dose are nuclide-dependent.
Dose factors for the five radionuclides limited by the drinking water pathway in the slag storage scenario have the widest confidence intervals of all those analyzed in this report. The 95/5 ratios for dose factors limited by the slag storage scenarios range from about 350 for Tc-99 to about 1,500 for Np-237. This is due to the uncertainties associated with the groundwater transport model and the timing of the scenario. Over the period of time addressed by this scenario there is a large uncertainty in the rate at which each radionuclide leaches to the drinking water supply and in the resulting radioactivity concentration in drinking water.
Draft NUREG 1640, Vol.1 4 112
f- !
Section 4 Recycle and Disposal of Steel }
Figure 4.7 indicates how many radionuclides have critical groups described by each of these h'd scenarios. Most limiting scenarios for steel recycle describe critical groups consisting of workers at scrap yards and steel refineries who transport, handle, and process scrap metal or refinery I
products such as slag and baghouse dust. Two critical group scenarios involving exposure to j cleared scrap account for 53 of the 85 radionuclides-scrap transportation for 39 and scrap !
handling for 14 radionuclides. Eleven radionuclides have critical group scenarios involvmg ;
exposure to EAF baghouse dust-dust transportation for 7 and dust processing for 4 l l radionuclides. Seven radionuclides are limited by the slag handling scenario. Four are limited f by exposure to finished metal from a BOF refinery during manufactunng.
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Recycle and Disposal of Steel Section 4 l There are three reasons why the scrap transportation scenario is important for the largest number of radionuclides. First, there is minimal delay between clearance of scrap and transporting it to the scrap vard so no significant radioactive decay occurs before the scenario begins.
Consequently, this scenario describes critical groups for many short-lived radionuclides that decay before later scenarios can occur. Second, unprocessed scrap has not yet been subjected to j dilution with other materials or chemical partitioning during refining. This means that the initial j radioactivity concentration is unchanged. Third, relatively large masses of scrap material are transported in each load so relatively larger amounts of radioactivity are present in this scenario than in most others. Because the scrap transportation scenario involves only the external dose l pathway, the radionuclides limited by this scenario are all gamma emitters. {
Radionuclides associated with slag, dust, and off-gas scenarios are those which concentrate in j these materials during the refining process. All of these scenarios include internal dose l pathways; inhalation of dust, inadvertent ingestion, consumption of drinking water or ingestion of garden produce. The radionuclides for which these material-specific scenarios are important all have relatively long half-lives and are alpha- or beta emitters that contribute to internal dose pathways.
Two types of radionuclides have critical groups consisting of members of the genm rublic ;
living in the vicinity of steel refineries. Critical groups for four volatile radionuclides with no j external dose component are described by the atmospheric release scenario. Critical group for five-water soluble radionuclides with no external dose component result from the ground water pathway of the slag storage scenario.
Residual radioactivity in consumer products rarely yields critical groups. Only one radionuclide (Mo-93) is limited by exposure of an individual in the general public to a manufactured product.
l There are four reasons for this. Fkst, the passage of time between clearance and the use of j consumer products allows many radionuclides to decay to very small concentrations. Second, j the amount of steel available from NRC licensed facilities is small compared to the total amount of steel that is recycled each year. It is not large even when compared to the capacity of some steel refineries. Mixing cleared steel with normal steel, even on a single charge basis, reduces concentrations of radioactivity in finished steel. Third, many radionuclides do not appear in finished steel. They are partitioned to slag or baghouse dust during refining. Finally, the relatively small size of consumer products compared to the amounts of steel encountered by refinery workers limits the amount of radioactivity to which any individual could be exposed. In contrast, workers at scrap yards and steel refineries can be exposed to relativdy large amounts of cleared steel before mixing, processing, or radioactive decay can take place.
The mean values of the derived surficial dose factors for each radionuclide in Table 4.11 represent the dose to the average member of the critical group exposed to residual radioactivity initially distributed over the surface of cleared iron and steel (Bq/cm 2 or pCi/cm 2
). Derived 1 surficial dose factors are calculated from mass-based dose factors by use of a surface-to-mass j ratio, appropriate for twical steel objects available for clearance. The value of The surface-to- l mass ratio is used tive surficial dose factors as described in Section 4.7.
Draft NUREG-1640, Vol.1 4-114 O
Section 4 Recycle and Disposal of Steel The calculation of derived surficial dose factors is probabilistic. The parameter SM is p\ represented by a distribution of values that incorporate the variability and uncertainty in the ld surface-to-mass ratio of steel objects available for clearance. This additional source of uncertainty results in wider confidence intervals for the surficial dose factors than for the mass-based dose factors from which they are derived. The relative importance of this additional uncertainty depends on the scenario. For scenarios with the narrowest confidence intervals, the added uncertainty can contribute as much as an additional 100% to the width of the confidence interval. The mass-based dose factor for the scrap transportation scenario has a 95/5 ratio of about 2 for most radionuclides. The corresponding derived surficial dose factors have a 95/5 ratio of about 4. The added uncertainty in surface-to-mass ratio has a relatively smaller effect on the confidence interval for scenarios with larger uncertainties, contributing an additional 10% to 50% to the 95/5 ratio.
Table 4.10 Steel recycle critical-group dose factors-mass (pSv/y per Bq/g) (mrem /y per pCi/g) g; 90% Confidence interval 90% Confidence interval g;
group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper !
Radionuclide factor bound) bound) factor bound) bound) Scenario j H-3 6.4E-04 3.8E-05 2.8E-04 2.4E-03 2.4E-06 1.4E-07 1.0E-06 8.8E-06FE-ATMO-REFINER-N i C-14 2.8E-03 1.7E-04 2.lE 03 7.8E-03 1.0E-05 6.3E-07 7.8E-06 2.9E-05FE-BOFM-HANDMAN-W Na-22 4. l E+02 7.3 E+01 2.9E+02 1.l E+03 1.5E+00 2.7E-01 1.lE+00 3.9E+00FE-EAFD-TRANSPO-W b P-32 1.3E-01 8.lE-02 1.3E-01 1.8E-01 4.8E-04 3.0E-04 4.9E-04 6.7E-04FE-SCRP-TRANSPO-W G' sE MFff5@ X3@M5g5Es2J M 6 5 ![ij sj s E 4 5 #5 4 ssp M i@ M Cl36 2.7E+00 5.lE-02 9.3E-01 1.lE+0! !.0E-02 1.9E-04 3.4E-03 4.0E-02FE-ATMO-REFINER-N K-40 5.2E+019.2E+00 3.8E+01 1.4E+02 1.9E-01 3.4E-02 1.4E-01 5.1E-01 FE-EAFD-TRANSPO-W Ca-41 1.3E-01 7.4E-04 2.7E-02 5.7E-01 4.9E-04 2.7E-06 1.0E-04 2.lE 03FE-SLAG-STORAGE N Ca-45 8.2E-02 3.7E-04 1.2E-02 3.4E-01 3.0E-04 1.4E-06 4.3E-05 1.2E-03 FE-SLAG-STORAGE-N hh72NiA+50$EE3)h I.S'075ltEd3 - 5 93E[03kd@[REN[S$h Mn 54 8.5E+015.3E+01 8.6E+01 1.2E+02 3.2E-01 2.0E-01 3.2E-01 4.3E-Ol FE-SCRP-TRANSPO-W ;
Fe-55 1.0E-03 5.6E 05 8.4E-04 2.6E-03 3.8E-06 2.lE-07 3.lE-06 9.5E-06FE BOFM-HANDMAN W l Co-57 3.8E+00 2.4E+00 3.8E+00 5.2E+00 1.4E-02 8.7E-03 1.4E-02 1.9E-02FE-SCRP-TRANSPO-W Co-58 9.5E4015.8E+01 9.6E+01 1.3E+02 3.5E-01 2.2E-01 3.5E-01 4.8E-Ol FE-SCRP-TRANSPO-W !
$ $i $h 5YN h. 55EESYE Y.$b Ni-59 4.5E-04 3.2E-05 4.0E-04 1.lE-03 1.6E-06 1.2E-07 1.5E-06 4.0E-06FE-BOFM HANDMAN-W j Co-60 2.5E+021.6E+02 2.6E+02 3.5E+02 9.4E-01 5.9E-01 9.5E-01 1.3E+00FE-SCRP-TRANSPO-W !
Ni-63 1.2E-03 7.3E-05 1.lE-03 2.8E-03 4.5E-06 2.7E-07 4.0E-06 1.lE-05FE-BOFM-HANDMAN-W Zn-65 2.1E+02 4.0E+01 1.5E+02 5.8E+02 7.9E-01 1.5E-01 5.4E-012.1E+00FE-EAFD-TRANSPO-W
$g h 30 ] M Se-75 3.6E+011.5E+00 2.2E+0i 1.2E+02 1.3E-01 5.6E-03 8.lE-02 4.3E-OlFE-EAFD-TRANSPO-W l
Sr-85 4.7E+012.9E+01 4.7E+01 6.4E+01 1.7E-01 1.lE-01 1.7E-01 2.4E-01 FE-SCRP-TRANSPO-W i p
i Sr-89 1.2E-01 7.lE-02 1.2E-01 1.6E-01 4.3E-04 2.6E-04 4.3E-04 5.9E-04FE-SCRP-TRANSPO-W j i
N) l
.4-115 Draft NUREG 1640, Vol. I
1 I
Recycle and Disposal of Steel Section 4 Table 4.10 Steel recycle critical-group dose factors-mass (pSv/y per Bq/g) (mrem /y per pCi/g) 90% Confidence interval 90% Confidence interval group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Sr 90 1.0E+01 3.9E-02 1.0E+00 3.4E+01 3.8E-02 1.4E-04 3.8E-03 1.3E-Ol FE-SLAG-STORAGE-N bNkh. [d3%][M NM7}@5h@M[WMM Mo-93 1.4E-02 2.5E-03 1.lE-02 3.7E-02 5.2E-05 9.2E-06 4.2E-05 1.4E-04FE-METL-SMOBJCT-N Nb-93m 8.4E-03 1.2E-03 5.6E-03 2.6E-02 3.lE-05 4.4E-06 2.lE-05 9.6E-05FE-SLAG-HANDLIN-W Nb-94 1.6E+021.0E+021.6E+02 23E+02 6. l E-01 3.8E-01 6. l E-01 83E-Ol FE-SCRP-TRANSPO-W Nb-95 7.2E+014.5E+01 7.3 E+01 9.9E+01 2.7E-01 1.6E-01 2.7E-01 3.7E-Ol FE-SCRP-TRANSPO-W
$ $ 'l0.$ $$ $ --
Tc 99 1.9E-01 1.8E-03 4.4E-02 9.2E-01 7.0E-04 6.8E-06 1.6E-04 3.4E-03FE-SLAG-STORAGE-N Ru-103 4.6E412.9E+014.7E+0i 6.4E+01 1.7E-01 1.lE-01 1.7E-01 2.4E-01 FE-SCRP-TRANSPO-W Ru-106 2. l E+01 1.3 E+01 2.1 E+01 2.8E+01 7.6E-02 4.7E-02 7.7E-02 1.0E-01 FE-SCRP-TRANSPO-W Ag 108m 1.6E+021.0E+021.6E+02 2.2E+02 6.0E-01 3.7E-01 6.0E-01 83E-Ol FE-SCRP-TRANSPO-W
..,.y,. ..,.,-- - -,.. w. ,.,_m-,., _y
@@fp@m _.y,, ,E-p[p:2M3&E4til, leg MEp3;23E44fij@3s43H3fE-EAFDMCESSMi Ag-l l0m 2.8E+021.8E+02 2.8E+02 3.9E+02 1.0E+00 6.5E-01 1.lE+001.4E+00FE-SCRP-TRANSPO-W Sb-124 1.8E+021.lE+021.8E+02 2.5E+02 6.7E-01 4. l E-01 6.7E-01 9.2E-O l FE-SCRP-TRANSPO-W I-125 2.7E+001.2E-01 1.3E+001.0E+0! 1.0E-02 4.5E-04 4.8E-03 3.8E-02FE-ATMO-REFINER N Sb-125 4.lE+012.5E+0! 4.1E+015.6E+01 1.5E 01 9.4E-02 1.5E-01 2.1E-01 FE SCRP-TRANSPO-W m, -.,.-.,,u--_._=.
E EIE523.d,m.,...-,-!53-,.!ppJEM22. Ej01,12.j4Eg_ ',23E41]L2E.02j9.9E-02%m
-,.,,-. 8E 0,l #h- ,,g,.y-.-
,. .,-O-REFINERM I 131 2.5 E+01 1.5 E+01 2.5E+01 3.6E+0! 9.3E-02 5.7E-02 93E-02 1.3E-01 FE-SCRP-TRANSPO-W Ba-133 2.8E+01 1.7E+0! 2.8E+013.8E+01 1.0E-01 6.4E-02 1.0E-01 1.4E-01 FE-SCRP-TRANSPO-W Cs 134 6.6E+021.1E+02 4.7E+021.7E+03 2.4E+00 3.9E-01 1.8E+00 63E+00FE-EAFD-TRANSPO-W Cs 137 2.6E+02 4.8E+01 1.8E+02 6.8E+02 9.5E-01 1.8E-01 6.7E-012.5E+00FE-EAFD-TRANSPO-W
~
hMhh37 ENS 7EE357N)d $05UW5h d d!'.5 @ $ @ M'S$ 6 Ce-144 33E+00 2.0E+00 33E+00 4.5E+00 1.2E-02 7.5E-03 1.2E-02 1.7E-02 FE-SCRP-TRANSPO-W Pm-147 1.lE-02 1.6E-03 7.4E-03 33E-02 4.2E-05 5.9E-06 2.7E-05 1.2E-04FE-SLAG-ilANDLIN-W Eu-152 1. l E+02 6.9E+01 1. l E+02 1.5 E+02 4.lE-01 2.6E-01 4.lE-01 5.7E-Ol FE-SCRP-TRANSPO-W Eu 154 1.2E+02 7.5E+01 1.2E+02 1.7E+02 4.5E-01 2.8E-01 4.5E-01 6.2E-Ol FE-SCRP-TRANSPO-W n mve- .n.y--r-n n e-n.~. m , ,-.m ,.~.v -.-- n n ,. m gi-J5, Shg1Ef00;6.6E-01; LIE +00!!3E'+00 ~3.9E-0312AB-03Q.9E 0U5 4E43fE-SCRP-TRANSPOl-Wih Re-186 2.5E-01 1.4E-01 2.4E-01 3.9E-01 9.lE-04 5.lE-04 8.8E-04 1.4E-03FE-SCRP-TRANSPO-W Ir 192 1.2E+02 63E+00 6.7E+014.0E+02 4.4E-01 23E-02 2.5E-01 1.5E400FE-EAFD-TRANSPO-W Pb-210 1.5E+02 2.4E+019.9E+0143E+02 5.7E-01 8.9E-02 3.7E-01 1.6E+00FE-EAFD-PROCESS-W Po-210 6.0E+018.lE+00 4.2E+01 1.6E+02
' 2.2E-01 3.0E-02 1.6E-01 6.0E-Ol FE-EAFD-PROCESS .W BM10Mi-,. w h. _--,,cJE3]3E-0332.SE-0216E-02,15E-04f2.7E-0510E44;2-h. .,, -
.-, mSCggglfN;-Wf;j Rn-222 8.6E+014.8E+018.2E+01 IJE+02 3.2E-01 1.8E-01 3.0E-01 5.0E-Ol FE-SCRP-TRANSPO-W Ra-223 1.8E+01 1.lE+0! 1.8E+012.5E+01 6.7E-02 4.2E-02 6.7E-02 9.4E-02FE-SCRP-TRANSPO-W Ra-224 6.l E+013.4E+01 5.9E+01 9.7E+01 23E-01 1.2E-01 2.2E-01 3.6E-Ol FE-SCRP-TRANSPO-W Draft NUREG-1640, Vol. I 4-116
Section 4 Recycle and Disposal of Steel
,s Table 4.10 Steel recycle criticaLgroup dose factors-mass h (pSv/y per Bq/g)
[j N
(mrem /y per pCi/g) g 90% Confidence interval 90% Confidence interval group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (rnedian) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ac 225 1.4 E+01 8.8E+00 1.4E+01 2.0E+01 5.3E-02 3.2E-02 5.2E-02 7.4E-02FE SCRP-TRANSPO W k h l E h 10$1[1[ M {l h k [3[5553M 5575 M 3 'M Ra-226 1.7E+021.lE+021.7E+02 2.4E+02 6.4E-01 4.0E-01 6.5E-01 8.9E-Ol FE-SCRP-TRANSPO-W Ac 227 3.4 E+02 4. l E+01 2. l E+02 1. l E+03 1.3E+00 1.5E-01 7.8E-01 3.9E+00FE-SLAG-HANDLIN-W Th-227 5.9E+00 3.6E+00 5.9E+00 8.IE+00 2.2E-02 1.3E-02 2.2E-02 3.0E-02FE-SCRP-TRANSPO-W Th-228 1.3E+02 7.9E+0! 1.3E+021.7E+02 4.7E-01 2.9E-01 4.7E-01 6.5E-01 FE-SCRP TRANSPO.W
?L&$$-$$W$k ,,,2 5?hhkh{ h Th-229 4.3E+02 6.2E+01 3.6E+02 1.0E+03 1.6E+00 2.3E-01 1.3E+00 3.8E+00FE-SCRP-HANDLIN-W Th-230 6.5E+019.3E+00 5.4E+0! 1.6E+02 2.4E-01 3.4E-02 2.0E-01 5.8E-01 FE-SCRP-HANDLIN W Pa-231 2.3E+02 3.0E+01 1.3E+02 6.7E+02 8.3E-01 1.lE-01 5.0E-012.5E+00FE-SLAG-HANDLIN W Th-231 1.5E-02 3.3E-03 1.lE-02 3.9E-02 5.5E-05 1.2E-05 3.9E-05 1.4E-04 FE-SCRP-TRANSPO-W
-,-,4 ,- m .n n .m. n- ,- n . e - n .,. , ,. n - - y ,- - n .- ~ ~. .
M232Hg2,,.9Egf.1 Egg 4gfQ6,.9E+02 j.,1E400,jll5E 0,138.,8E,-01p.6E+00lFE,SCRP-HAMIJNMg Pa-233 1.3 E+01 8. l E+00 1.3 E+01 1.8 E+01 4.9E-02 3.0E-02 4 '.E-02 6.8E-02FE-SCRP-TRANSPO-W U-233 3.4E+014.6E+00 2.8E+01 8.l E4 01 1.2E-01 1.7E-02 1.0E-01 3.0E-Ol FE-SCRP-HANDLIN-W g Th 234 7.3E-01 4.5E-01 7.4E-01 1.0E+00 2.7E-03 1.7E-03 2.7E-03 3.7E-03 FE-SCRP-TRANSPO-W
! U-234
',V - - ,
3.3E+014.5E+00 2.7E+01 7.9E+01 1.2E-01 1.7E-02 1.0E-01 2.9E-01 FE-SCRP-HANDLIN-W yym . -- __.o- .r e -r- - - e.--w ---.-- c U-235,qh3;.2EMij4{l E400t 2.2Ed01 9.3E+01 :12E 01)1:5E-02L86@.5,E-uMm SI,.fGiHAMWg +.
Np-237 2.0E+03 8.4E+00 3.lE+02 7.3E+03 7.4E+00 3.lE-021.lE+00 2.7E+0i FE-SLAG-STORAGE-N Pu-238 7.lE+019.8E+00 5.9E+01 1.7E+02 2.6E-01 3.6E-02 2.2E-01 6.4E-Ol FE-SCRP-HANDLIN W U-238 2.9E+014.lE+00 2.4E+017.lE+0! 1.lE-01 1.5E-02 9.0E-02 2.6E-OlFE-SCRP HANDLIN-W Pu-239 7.6E+01 1.0E+01 6.3E+01 1.8E+02 01
. , , , , , n,, . ,,,w 2.8E-01
...r, .n - n-3.9E-02 2.3E.m m ,..ms#$,16E+g0lf.0E+01,jpMI:18E+02 2.8E-Ol33.9En2.3Epij6JE-0th.,w,n e-.6.8E-OlFE-SCRP HANDLIN W .
1%2$04: SCRP;HANDLIN,, n. -nh.
Pu-241 1.2E+001.7E-01 1.0E+00 3.0E+00 4.5E-03 6.2E-04 3.8E-03 1.lE-02FE-SCRP-HANDLIN W Am-241 1. l E+021.3 E+01 8.0E+01 3.4 E+02 4.2E-01 4.9E-02 3.0E-01 1.3E+00FE-SLAG-HANDLIN-W Cm-242 4.3E+00 6.7E-01 3.6E+00 1.0E+01 1.6E-02 2.5E-03 1.3E-02 3.8E-02FE-SCRP-HANDLIN-W Pu-242 7.3E+019.9E+00 6.0E+01 1.8E+02 2.7E-01 3.7E-02 2.2E-01 6.5E-Ol FE-SCRP-HANDLIN-W Cm-244 6.3E+017.4E+00 4.lE+0! 1.9E+02 2.3 E-01 2.7E-02 1.5E-01 7. l E-Ol FE-SLAG-HANDLIN-W f
\ !
V 4-117 Draft NUREG-1640, Vol. I
Recycle and Disposal of Steel Section 4 Table 4.11 Steel recycle critical-group dose factors-surficial (pSv/y per Bq/cm 3) (mremly per pCi/cm')
90% Confidence interva! 90% Confidence interval Critical- Cn. .ucal-group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario H-3 4.8E-04 2.2E-05 2.lE-04 1.7E 03 1.8E-06 8.lE-08 7.6E-07 6.3E-06 FE-ATMO-REFINER-N C-14 2.lE-03 1.3E-04 1.4E-03 6.5E-03 7.8E-06 4.9E-07 5.2E-06 2.4E-05 FE-BOFM HANDMAN-W Na-22 3.2E+02 4.6E+01 1.9E+02 9.2E+02 1.2E+00 1.7E-01 7.2E-013.4E+00 FE-EAFD TRANSPO-W P-32 9.9E-02 4.2E-02 9.2E-02 1.8E-01 3.7E-04 1.6E-04 3.4E-04 6.6E-04 FE SCRP-TRANSPO-W
? 55 5 h h k $ $ $ $$ h Cl-36 2.lE+00 3.lE-02 6.6E-01 8.6E+00 7.7E-03 1.lE-04 2.4E-03 3.2E-02 FE-ATMO-REFINER-N K-40 4.0E+015.7E+00 2.6E+01 1.2E+02 1.5E-01 2.lE-02 9.6E-02 4.5E-01 FE-EAFD-TRANSPO-W Ca-41 9.8E-02 5.4E-04 1.9E-02 3.6E-01 3.6E-04 2.0E-06 7.lE-05 1.3E-03 FE-SLAG-STORAGE-N Ca-45 2.2E-04 1.0E-06 3.0E-05 8.5E-04 FE-SLAG-STORAGE-N
.r , 6.1E-02
,m 2.7E-04 w.c- 8.IE-03
- n.mn.2.3E.01
~ - , ~ ~ _ .,-.->. -c a ,-m bf.-5,@w'g,.1:p9E,g 8,g,sigg+00 33E100 p.9E-9,3J2 9E-031n:m.v)].3M2,FE-SCRP,MSPO-h; 64E_031 Mn 54 6.4 E+01 2.7E+01 6.0E+01 1.2 E+02 2.4E-01 1.0E-01 2.2E-01 4.3E-01 FE-SCRP-TRANSPO-W Fe-55 7.6E-04 4.7E-05 5.6E-04 2.1E-03 2.8E-06 1.7E-07 2.IE-06 7.6E-06 FE-BOFM HANDMAN-W Co-57 2.9E+001.2E+00 2.7E+00 5.3E+00 1.1 E-02 4.5E-03 9.9E-03 1.9E-02 FE-SCRP-TRANSPO.W Co-58 7.2E+0! 3.0E+016.6E+01 1.3E+02 2.7E-01 1.lE 01 2.5E-01,.-,..,,..r.. 4.8E-01 FE,SCRP-TRANSPO-W ._ . m m .
..,.7. ,. 7 y ... ..-,m,._ m .- ..-.t.._
Fe-59 NM 8.7E+003T.6E+0l!.8.0E+01;l .6Ef02 3.2E-Olf13E 01:3.0E-01J5.8E-01,FE-SC_RP-TRANSMWyfj .
Ni-59 3.4E-04 2.2E-05 2.7E-04 9.3E-04 1.2E-06 8.lE-08 9.8E-07 3.4E-06 FE-BOFM-HANDMAN-W Co-60 1.9E+02 8.2E+0! 1.8E+02 3.5E+02 7. l E-01 3.0E-01 6.6E-01 1.3 E+00 FE-SCRP-TRANSPO-W Ni-63 9.lE-04 5.2E-05 7.6E-04 2.5E-03 3.4E-06 1.9E-07 2.8E-06 9.lE-06 FE-BOFM-HANDMAN-W Zn-65 1.6E+02 2.3E+01 1.0E+02 4.9E+02 6.0E-01 8.5E-02 3.8E-01 1.8E+00 FE-EAFD-TRANSPO-W-.
r-. ,.m.,,yr-,,--,-,.--._,-. .
.r..,,.-.~.,., .
Cs 5~73M l.6E+00 L5:6E.'01t 1.4Ef00 3J5.8E-0312,,lE.0325.0E-03))l.2E E+00 02FE_-SCRP.,TRANSPO-M Se-75 2.7E+01 1.0E+00 1.6E+01 9.3 E+01 9.8E-02 3.8E-03 5.9E-02 3.4E-01 FE-EAFD-TRANSPO-W Sr-85 3.6E+01 1.5E+01 3.3 E+01 6.5 E+01 1.3 E-01 5.5E-02 1.2E-01 2.4E-01 FE-SCRP-TRANSPO-W Sr-89 8.8E-02 3.7E-02 8.lE-02 1.6E-01 3.3E-04 1.4E-04 3.0E-04 5.9E-04 FE-SCRP-TRANSPO-W Sr-90 7.5E+00 2.3E-02 7.3E-01 2.2E+01, 2.8E-02 8.6E-05 2.7E.03 8.2E.02 FE,.-
- m. SLAG.,
- , _STORAGE-N
, , .me
.,- m .,.r.o.,-_.- - ,,.x,- - - .,,-c- .., - m -.- - ,..r._-,-. -, , m X-9.!g@jM2-p@ll,t{gfM2dMyggpl RMif.1_E,,0,,4jppEM.8E-03FE,-SCR[,TRjAN _PO,Wjj Mo-93 1.lE-02 1.4E-03 7.9E-03 3.lE-02 3.9E-05 5.4E-06 2.9E-05 1.lE-04 FE-METL-SMOBJCT-N Nb-93m 6.4E-03 8.0E-04 3.7E-03 2.lE-02 2.4E-05 3.0E-06 1.4E-05 7.6E-05 FE-SLAG-HANDLIN-W ,
I Nb-94 1.2E+02 5.3E+01 1.1E+02 2.3E+02 4.6E-01 2.0E-01 4.2E-01 8.4E-01 FE-SCRP-TRANSPO-W l
Nb-95 5.5E+01 2.3 E+01 5. l E+01 9.9E+01 2.0E ,01 8.5E-02 1.9E-01 3.7E-Ol FE-SCRP-TRANSPO-W
~w ,nn r n m ,,. w w .v.r n -.r- n - .... - m .- n . - ~. ~ w- - -
Tc-99 1.4E-01 1.3E-03 3.4E-02 6.7E-01 5.3E-04 4.9E-06 1.3E-04 2.5E-03 FE-SLAG-STORAGE-N Ru-103 3.5E+01 1.5 E+01 3.2E+01 6.4E+01 1.3E-01 5.4E-02 1.2E-01 2.4E-01 FE-SCRP-TRANSPO-W Ru-106 1.6E+01 6.6E+ 00 1.4E+01 2.8 E+01 5.8E-02 2.5E-02 5.4E-02 1.lE-01 FE-SCRP-TRANSPO-W Ag-108m 1.2E+02 5.2E+01 1.1E+02 2.2E+02 4.5E-01 1.9E-01 4.2E-01 8.3E-01 FE-SCRP TRANSPO Wy. ,
,.n,. .m
...~,, . ,yA ,.-_-Ij2E-03fij5 R8pE-04f3.7E-03FE.E FD
... ,,..f m - -,, _ -.
c@.~.m, .n$QE-0113,198 0g2j2Ej0Q@p ;m.y...,g.~,E 0?jpg 1 1
Draft NUREG-1640, Vol.1 4 118
l l
Section 4 Recycle and Disposal of Steel Table 4.11 Steel recycle critical-group dose factors-surficial l (pSv/y per Bq/cm2 ) (mrem /y per pCi/cm ) l l
g 90% Confidence interval 90% Confidence interval !
g group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (medien) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag-110m 2.1E+02 9.1E+012.0E+02 3.9E+02 7.9E-01 3.4E-01 7.3E-01 1.4E+00 PE SCRP-TRANSPO-W Sb-124 1.4E+02 5.7E+01 IJE+02 2.5E+02 5.lE-01 2.lE-01 4.7E-01 9.2E-Ol FE-SCRF TRANSPO-W 1-125 2.lE+00 8.lE-02 9.0E-01 8.0E+00 7.8E-03 3.0E-04 3.3E-03 3.0E-02 FE-ATMO-REFINER-N Sb-125 3.1 E+01 1.3 E+01 2.9E+01 5.6E+01 1.1 E-01 4.8 E-02 1. l E-01 2.1 E-01 FE-SCRP-TRANSPO-W 4
- gy w .,x. A .- ~ .p..p s
.g
. , ; 7w,agg y g3gy gg r % .m. 4, ' -
.....t u ..
e
- s. .. .
I 1-131 1.9E+01 8.0E+00 1.7E+01 3.4E+01 7.0E-02 3.0E-02 6.4E-02 1.3E-01 FE-SCRP-TRANSPO-W l
Ba-133 2.1E+019.0E+00 2.0E+013.9E+01 7.8E-02 3JE-02 7.2E-02 1.4E-01 FE-SCRP-TRANSPO-W '
Cs-134 4.9E+02 7.2E+0133E+021JE+03 1.8E+00 2.7E-01 1.2E+00 4.9E+00 FE-EAFD-TRANSPO-W Cs-137 2.0E+02 'i OE+01 IJE+02 5.9E+02 7.3E-01 1.0E-01 4.7E-01 2.2E+00 FE-EAFD-TRANSPO-W m, - .
.. n .
9NW.E!IS m$EE. r-.upgEp00 gMp,2E-qp,gll,@}.02,,WMWgg Cc-144 2.5E+001.lE+00 2.3E+00 4.5E+00 9.2E-03 3.9E-03 8.5E-03 1.7E-02 FE-SCRP-TRANSPO-W Pm-147 8.4E-03 9.4E-04 5.2E-03 2.5E-02 3.lE-05 3.5E-06 1.9E-05 9.2E-05 FE-SLAG-HANDLIN-W I Eu-152 8.4E+01 3.6E+01 7.8E+01 1.5 E+02 3.lE-01 13E-01 2.9E-01 5.7E-Ol FE SCRP-TRANSPO-W Eu-154 9.2E+0! 3.9E+018.5E+01 1.7E+02 3.4E-01 1.4E-01 3.2E-01 6.2E-01 FE-SCRP-TRANSPO-W kb5 $ h5 5h WY Re-186 1.9E-01 7.5E-02 1.7E-01 3.5E-01 6.9E-04 2.8E-04 6.2E-04 1.3E-03 FE-SCRP-TRANSPO-W Ir-192 8.9E+013.7E+00 4.9E+013.4E+02 33E-01 1.4E-02 1.8E-01 1.2E+00 FE-EAFD-TRANSPO-W Pb-210 1.2E+02 1.4E+01 6.8E+01 3.5 E+02 4.3E-01 53E-02 2.5E-01 1JE+00 FE-EAFD-PROCESS-W Po-210 4.4E+0153E+00 3.0E+01 13E+02 1.6E-01 1.9E-02 1.lE-01 4.9E-Ol FE-EAFD-PROCESS-W Rn-222 bb 8' kh 6.5E+01 2.6E+01 5.9E+01 1.2E+02 2.4E-01 9.6E-02 2.2E-01 4.5E-01 FE-SCRP-TRANSPO-W Ra-223 1.4E+01 5.7E+00 1.3E*01 2.5E+01 5.lE-02 2.lE-02 4.7E-02 9.1E-02 FE-SCRP-TRANSPO-W Ra-224 f.6E+01 1.8E+0! 4.2E+01 8.8E+01 1.7E-01 6.8E-02 1.5E-01 3.2E-01 FE-SCRP-TRANSPO-W Ac-225 1.lE+0! 4.5E+00 9.9E+001.9E+01 4.0E-02 1.7E-02 3.7E-02 7.1E-02 FE-SCRP-TRANSPO-W Ra-226 b.525 N b.bb Nkb IJE+02 5.6E+01 1.2E+02 2.4E+02 4.9E-01 2.lE-01 4.5E-01 8.9E-01 FE-SCRP-TRANSPO-W Ac-227 2.5E+02 2.5E+0i 1.5E+02 7.7E+02 9.4E-01 93E-02 5.6E-012.8E+00 FE-SLAG-HANDLIN W Th-227 4.4E+001.9E+00 4.1E+00 8.1E+00 1.6E-02 6.9E-03 1.5E-02 3.0E-02 FE-SCRP-TRANSPO-W Th-228 ' 9.6E+01 4. l E+01 8.9E+01 1.8E+02 3.6E-01 1.5E-01 33E-01 6.5E-Ol FE-SCRP-TRANSPO-W
-. $ Y5 Th-229 3.3E+02 3.8E+012.4E+02 8.6E+02 1.2E+00 1.4E-01 9.0E-013.2E+00 FE-SCRP-HANDLIN W Th-230 4.9E+015.6E+001.7E+01 1JE+02 1.8E-01 2.1E-02 1.4E-01 4.8E-01 FE-SCRP-HANDLIN-W Pa-231 1.7E+02 2.0E+019.7E+01 SJE+02 6.3E-01 7.3E-02 3.6E-01 1.9E+00 FE-SLAG-HANDLIN-W Th 1.l E-02 1.9E 4.2E-05 7.0E-06 2.9E-05 1.2E-04 FE-SCRP-TRANSPO-W p 4. . 231%y m i- . .-M,-03 .s 7.7E-03 3.2E-02AE S M j9.2B0gdn i3B,$
,E3,gt,g hwuNgyg
( A
(
4-119 Draft NUREG-1640, Vol.1 L
I 4
l Recycit and Disposal of Steel Section 4
' Table 4.1I Steel recycle criticaQrup p ' cors-surficial (kSv/y per Bq/cm2 ) (m n [,yj rj /cm ) 2 g; ,, 90% Confidence interval g 90'4 ' '+- e interval group 5* 50* 95* group **
. A 95* .
dose (lower (median) (upper dose (lowe ,cian) (upper l Radionuclide factor bound) bound) factor bounce bound) Scenario l
Pa-233 1.0E+014.2F'90 9.3E+001.8E+01 3.7E-02 1.5E-02 3.4E-02 6.8E-02 FE-SCRP-TRANSPO-W l U-233 2.5E+01 2.8E+00 1.9E+01 6.8 E+01 9.4E-02 1.0E-02 7.0E-02 2.5E-01 FE-SCRP-HANDLIN-W Th-234 5.5E-01 2.3E-01 5.lE-01 1.0E+00 2.0E-03 8.5E-04 1.9E-03 3.7E-03 FE-SCRP-TRANSPO-W U-234 2.5E+0! 2.7E+001.9E+016.6E+01 9.2E-02 1.0E-02 6.9E-02 2.4E-01 FE-SCRP-HANDLIN-W
'N' _h Ni h 2f h E 5 k N E E E k @ d k Np-237 1.4E+03 6.1E+00 2.2E+02 6.0E+03 5.3E+00 2.2E-02 8.0E-012.2E+01 FE-SLAG-STORAGE-N Pu-238 5.4E+016.0E+00 4.0E+01 1.4E+02 2.0E-01 2.2E-02 1.5E-01 5.3E-01 FE-SCRP-HANDLIN-W U-238 2.2E+01 2.5E+00 1.7E+01 5.9E+0! 8.2E-02 9.1E-03 6.2E-02 2.2E-01 FE-SCRP-HANDLIN-W Pu-239 5.8E+0! 6.4E+00 4.3E+01 1.5E+02 2.!E-01 2.4E-02 1.6E-01 5.7E-01 FE-SCRP HANDLIN-W kb b bNNN h___ fb.@}[6hl)$ h,hJgEy3j Pu-241 9.3 E-01 1.0E-01 7.0E-01 2.5E+00 3.4E-03 3.8E-04 2.6E-03 9.lE-03 FE-SCRP-HANDLIN-W Am-241 8.5 E+01 1. l E+01 6.3 E+01 2.2 E+02 3.2E-01 4.0E-02 2.3E-01 8.3E-01 FE-SLAG-HANDLIN-W Cm-242 3.2E+00 4.lE-01 2.4E+00 8.6E+00 1.2E-02 1.5E-03 8.9E-03 3.2E-02 FE-SCRP-HANDLIN-W Pu-242 5.5E+016.lE+00 4.lE+01 1.5E+02 2.0E-01 2.2E-02 1.5E-01 5.4E-01 FE-SCRP-HANDLIN-W Cm-244 4.8E+014.6E+00 2.9E+01 1.5E+02 1.8E-01 1.7E-02 1.lE-01 5.5E-01 FE-SLAG HANDLIN-W l
l Dra't NUREG-1640, Vol.1 4-120 O
I 1
l, d
Section 5 Evaluation of Copper 5 EVALUATION OF RECYCLE AND DISPOSAL OF COPPER SCRAP V
Twenty-three potential exposure scenarios for cleared copper scrap that are realistically based on current American industries are evaluatedin this section. As in the steelevaluation, scenario categories include handling and processing, storage, transportation, product use, and disposal. A ;
radionuclide-specific, probabilistic dose factor distribution was calculated for the members of all exposed groups, and a dose factor for an average member of each critical group was calculated in the same manneras forsteelrecycle. The mean dose factorforeach criticalgroup is reportedin normalized units ofpSv/y per Bq/g scrap (mrem /y per pCi/g) and pSv/y per Bq/cm' scrap (mrem /y per pCi/cm') for each radionuclide. Dose tactors at the 5*, 50*, and 95* percentiles are also reported.
The copper recycle analyses yield similar cnticalgroups as steel recycle. The most common critical groups are commercial truck drivers carrying cleared copper scrap and workers at copper refineries.
Scenarios involving transport of scrap material resulted in cntical group designation for approximately half (47) of the 65 radionuclides in the analysis. Other scenarios identifying critical groups for many radionuclides involve handling refinery slag (31 radionuclides). Only ons criticalgroup involves the use .
of steel consumerproducts: use of a g2neric small object close to the body made from refined copper. l Mean cntical-group dose factors for the radionuclides range from a high of 3.3E+02 pSv/y per Bq/g (1.2 mrem & perpCi/g) for Th-229 to a low of 4.2E-04 pSv4per Bq/g (1.6E-06 mrem & perpClig) for Ni-59.
The surticialmean critical-group dose factors range from 2.9E+2 pSv/yper Bq/cm"(Th-229) down to 3.6E-4 pSv& per Bq/cm' (Ni-59). The Th-229 dose factors are not unusual for the set of copper dose factors, as 16 other dose factors are within a factor of three of the Th-229 values. Seventy-three of the radionuclide-specific, copper critical-group dose factors are 135 pSv/y per Bq/g a rlower (0.5 mrem /y 0% perpCi/g).
()
This section describes the technical evaluation of the recycle and disposal of copper scrap that could be cleared from licensed facilities. Similar to steel scrap (Section 4), the flow of cleared material was probabilistically modeled, distributions of radionuclide concentrations in refined and dispoed materials were calculated, and the mean dose factors for each potentially exposed group were estimated.
5.1 Introduction to Analysis j The analysis process for calculating potential exposure from copper recycle and disposal is l essentially the same as described previously for iron and steel. A material flow model specific to l
copper scrap was developed, radionuclide concentrations were calculated, and scenario '
evaluations were conducted. Besides the material flow model (and calculated concentrations in ,
refined and disposed materials), there are only minor differences between the steel and copper l scrap analyses. There are several minor scenario parameter differences and one additional l exposure scenario that is specific to recycled copper scrap (described in Section 5.6).
O O
5-1 Draft NUREG-1640, Vol. I
Evaluation of Copper Section 5
(
5.2 Flow of Recycled and Disposed Copper Scrap The material flow model for copper represents the general processes that cleared material would go through from the time it is cleared by a licensed facility to the time of final disposal. Similar to steel, the copper material flow model is comprised of two types of models: conceptual and mathematical. The conceptual model describes the copper refining process and defines the limits of this malysis, while the mathematical model presents the mathematical equations that implement the information presented in the conceptual model.
The material flow model is based on a literature review of the U.S. secondary copper industry. It is intended to provide a defensible basis for developing appropriate exposure scenarios. In addition, the output of the material flow model provides key input to the dose calculations for each scenario. This input consists of radionuclide-specific concentrations in recycle byproducts, in effluents, and in waste products of the refining process. Because of the number of scenarios being analyzed and the differing times at which they occur, the mathematical model presented in this section does not include radioactive decay. However, radioactive decay is taken into account in the individual scenarios, in the same manner as in the steel recycle analysis.
This section presents the conceptual model that describes the movement of scrap through the normal refining process, beginning with the production of scrap, through refining, manufacturing, product use, and ending with disposal. Figure 5.1 presents a schematic diagram of the overall material flow for copper scrap. The mass of material and the amount of radioactivity are tracked separately so that the radioactivity concentration can be calculated at any point in the flow. The steps or processes in the refining process are shown in Figure 5.1.
Each of these are discussed separately in the following subsections.
5.2.1 Sources of Material Recyclers are the producers of scrap metal. Recyclers can be the general public (e.g., recycling copper wire), industry (e.g., recycle disused copper items), or manufacturers (e.g., scrap produced during manufacture of end products).
A total of 1.32E+6 t (1.5E+6 ton) of secondary copper-scrap-was consumed in the U.S. in 1995 (USBM 1997). Similar to steel scrap, there are three types of scrap metal used in the copper-making industry: home, new, and old. Home scrap consists of unusable metal produced during the processing or fabrication of copper into a form usable for manufacturing. Home scrap ,
is usually high-grade metal with very few impurities. Even though home scrap is produced at the !
refinery, it is still considered a secondary metal because it is not the processed raw material. !
New scrap is produced during manufacture of end products. New scrap also is high-grade metal with very few impurities. Oldscrap includes obsolete, wom-out or broken products that have been used by the general public or industry. Old scrap is usually low-grade metal and the chemical composition is not well-known. Therefore, it must first be sorted, sized, and classified.
Cleared scrap metal from the nuclear industry is considered old scrap.
Draft NUREG-1640, Vol.1 5-2 i
Section 5 Evaluation of Copper
._ Copper-rich Slag _ _ ,
Y
. - _ _ Slag _ _ . . _ . _ _ _ . _ _ _ _ _
Blast Fumace
_ -__ _). .
air
->j Stack I w y
slag ) Converter >- Electrorefining ) Transportation Reverberatory matte y
Fumace matte
-A A. 2, ). maupturias Processing Transportation to Refinery Y A Transportation Recycle Handlirn 4
Processor Y
Tra rtation Handling Use
\ A Eating V Recyclers /
/ Direct Disposal Disposal .
Figure 5.1 Material flow for copper scrap l The main producer of the scrap assumed for this study is the nuclear industry (decommissioned material from nuclear facilities), which consists mainly of commercial power plants, test and research reactors, and industrial nuclear facilities. Other producers of such scrap include the Department of Energy (DOE) weapons complex and the Department of Defense (DOD), which would contribute slightly contaminated scrap primarily from conventional weapons testing and army and navy test reactors. Approximately 1.0E+3 t/y (1.1E+3 ton /y) of potentially recyclable copper and brass scrap metal is generated each year from licensed facilities. Increased dismantling and decommissioning activities could result in approximately 1.80E+4 t/y (2.0E+4 ton /y) of copper scrap (NUREG/CR-5610') for a limited number of years. Current home, new,
' Recycle / Reuse Literature Search Report, SAIC.1994, scheduled to be published as NUREG/CR-5610.
53 Draft NUREG-1640, Vol. I
1 l
Evaluation of Copper S:ction 5 and old scrap is essentially uncontaminated. Similar to the steel analysis, cleared copper scrap is i assumed to be mixed with a single source of uncontaminated scrap.
5.2.2 Transportation and Processing !
l' Scrap copper cleared from a nuclear facility must be transported to a scrap dealer or processor; this would most likely be done by a commercial company. Because not all licensee scrap is likely to be suitable for recycle, some would be transported directly to a disposal site. In all cases, transportation could occur either by truck or rail.
After scrap is processed at a scrap dealer, it is transported by either rail or truck to a refinery.
The types of activities performed at the scrap refinery include shearing the metal into size, briquetting or crushing thin and lightweight materials (e.g., tumings and borings), magnetically separating iron, and cleaning and degreasing (Bever 1986). Slag, metal products, and dust produced at the refinery or mill are transported to manufacturers or processors by either truck, rail, or waterway.
5.2.3 Copper Mills Copper scrap can be used in many different types of refineries and mills. According to Smith (1996) approximately 30% of the scrap consumed was in copper smelters and refiners, ? % in brass mills,10% in brass and bronze ingot makers, and the remaining by miscellaneous manufacturers, foundries, and chemical plants. Brass mills use mainly new scrap while copper smelters and refiners use mainly old scrap. Because it is possible and likely that' scrap from the nuclear industry would be recycled in brass mills as well as copper smelters and refiners, both have been analyzed. The typical furnace that scrap would enter for copper recycling is the reverberatory furnace. The output from the reverberatory furnace can then be further refined in a converter and electrorefiner.
i 5.2.3.1 Reverberatory Furnace In the reverberatory furnace, the lighter impurities combine and float to the top of the melt as a l slag that is skimmed off and discarded, while the copper, iron, most of the sulfur, and any !
contained precious metals form a product know as " matte"(USBM 1985). This molten matte is l
collected and is drawn off from the lower part of the furnace. The copper matte from the j reverberatory furnace has a typical copper concentration between 50% and 75% (EPA 1995).
According to industry, a typical reverberatory furnace operates at a temperature of about 1100 C (2000 F). Very small amounts of sand and limestone additives are typically added to the furnace.12 A typical charge size for a reverberatory furnace ranges from 18-499 t (20-550 tons).'
' Personal communication between M. Anderson, SAIC and G. Golebiowski, Muellar Copper Tube Co., May 27,1997.
2 Personal communication between M. Ar.derson. SAIC and 1 Schuster, Cerro Copper Tube Co.. May 27.1997.
Draft NUREG-1640, Vol.1 5-4 1
l Section 5 Evaluation of Copper L
An average value of 227 t (250 tons) is used2 in the model. A typical copper refinery using a
~
reverberatory fumace has an average of 1016 t (1,120 ton) of charge / furnace-day (Butts 1970).
This results in about 4 charges / day for a single furnace or 1460 charps/ year.
The brass refineries operate at temperatures similar to the reverberatory furnace. Brass refmeries use either rotary or electric furnaces. A typical charge size for a rotary furnace ranges from 9-45 t (10-50 tons), while the electric fumace has a typical charge size of about 2.3 t (2.5 ton). There is no slag produced in the electric furnace. The output of a reverberatory furnace in brass refineries is assumed to be similar to the output of the copper refinery reverberatory fumace.
5.2.3.2 Converter The matte from the reverberatory fumace is fed into the converter where air flowing through the matte burns off the sulfur, oxidizes the iron for removal in a slag, and yields a product called
" blister" copper (USBM 1985). A typical converter must operate between 1220*C and 1350*C (2230*F-2460 F)(Butts 1970). Below 1220 C the temperature is too low to form a true slag, while above 1350 C the heat will wear out the basic lining very rapidly. Converter slags are generally disposed of by pouring them back into the blast fumaces (Butts 1970). s l 5.2.3.3 Electrorefiner The blister copper from the converter is approximately 99.5% Cu. It is first cast into anodes that are fed into the electrorefiner. Electrorefining consists of placing the impure copper anodes and thin, pure-copper cathode starting sheets in a CuSO4 -H 2 SO4-H 2 O electrolyte and passing a direct ,
current between them. The electric current causes the copper to dissolve from the anode and plate in pure form on the cathode (Bever 1986). Cathodes are typically grown for 10-14 days to a weight of about 150 kg (330 lbs). The anodes are left in the electrolytic cells until they are almost completely dissolved, usually forming two batches of cathodes. The undissolved anode scrap is washed, melted, and recast as fresh anodes for further refming (Bever 1986). Solid impurities in the anodes fall to the bottom of the cell as a sludge where they are ultimately )
l collected and processed for the recovery of precious metals such as gold and silver. This l material is known as " anode slime" (EPA 1986). I i
l The fumes that are generated during the refining of copper scrap are captured by the primary l
exhaust hood and transported via a duct system to a baghouse. The baghouse used in the refining i j of copper scrap is similar to those used in the iron and steel industry. Therefore, the same l parameters for the baghouse are used for tne recycling of copper (e.g., temperature, efficiency). i The baghouse dust produced during the refiming of copper scrap is not considered hazardous. 2
. Personal communication between M. Anderson. SAIC and G. Golebiowski, Muellar Copper Tube Co., May 27,1997.
2 Personal communication between M. Anderson, SAIC and J. Schuster, Cerro Copper Tube Co., May 27,1997.
V ;
5-5 Draft NUREG.1640, Vol. I
Evaluation of Copper Section 5-5.2.3.4 Output of Refinery Processes During each of the refining processes, the original metal separates into four different end products: off-gas, dust, slag, and metal (Figme 5.1). Each radionuclide is partitioned into these four materials in an element-specific manner This process is described using mass partitioning factors and element-specific elemental partitioning factors. Partitioning factors are defined as the fraction of original radionuclide concentration or masa entering the refinery fumace that would be present in various end products. These partitiening factors for copper are discussed in detail in Section 5.3.
Each of the end products undergoes a different process, use, and final disposal process. The off-gas includes elements that are completely volatilized into stable gases or very fine particles during refining and then exit the refinery stack. Dust includes elements that are volatilized from the fumace, form particulates when cooled, and are collected in baghouse filters. (The air pollution control systems are not 100% efficient, and a small percentage of the dust entering the baghouse is released into the atmosphere with the off-gas.)
Slag is not considered a hazardoer waste, therefore, it can be reprocessed or directly disposed of.
After slag is removed from the fumace and cooled, it is stored in piles outdoors at the refinery until it is either used by the refinery or transported to a processor. Because ofits high metal content, slag is usually fed back into the furnace as input material.
Manufacturing and processing converts slag and metal products created at the refineries and mills into finished products. Manufacturing involves activities such as cutting and shaping the metal.
Processing of slag involves crushing and sizing. After a metal product or slag is manufactured l into a finished product, it must be transported and distributed to the general public (i.e., end !
I user). Facilities involved in the distribution of finished metal products include stores and warehouses. Slag is usually distributed and transported directly from the refinery where it is produced or the manufacturer where it is processed.
5.2.4 Product Use Finished metal products, and occasionally slag, are used by the public for many applications.
The largest use of copper metal is in electrical equipment and supplies. Copper and copper alloy wire are used in manufacturing electric motors and generators, power transmission lines, etc.
Copper is also used in producing nonelectrical industrial machinery and parts, such as automobile parts, railroad equipment, and construction materials (e.g., roofing, gutters, nails, plumbing)(USBM 1985). When copper slag is used instead of being recycled, its use is similar to that ofiron and steel slag (roadbed, railroad ballast).
Draft NUREG-1640, Vol. ! 5-6 O
p I.
Section 5 Evaluation of Copper
!- 5.2.5 Disposal i
- The ultimate endpoint for finished metal products, slag, and dust is disposal in a public sanitary landfill (Resource Conservation and Recovery Act (RCRA) Subtitle D). Discarded end products,
- waste from manufacturing, slag direct from the refinery, products made from slag, scrap not suitable for recycle, and dust are all metal byproducts that could be disposed ofin a sanitary landfill.
o l 5.3 Mass and Elemental Partitioning Factors for Refinery Operations For this analysis, the mass of scrap metal entering a furnace during the refining process is redistributed into the three immediate products: metal product, slag, and dust. Radioactivity in incoming scrap ~ metal is redistributed among those products, as well as in the off-gas leaving the refinery stack.
5.3.1 Mass Partitioning Factors The mass partitioning factors for copper were estimated using information obtained from industry contacts. Mass partitioning factors were determined for the metal product, slag, and dust. Between 90% and 96% of the metal mass entering the reverberatory furnace ends up in the metal product.i.2 Because the dust produced during the recycling of copper scrap is not l\ f considered hazardous, a record of the mass of dust produced per charge is not typically kept by refineries. However, industry estimates that about 1-2% of the original mass entering the -
furnace ends up in the dust. More dust is produced with dirtier scrap. Because very few additives are added during the recycling of copper, the remaining fraction is assumed to be the mass partitioning to slag.
No information is readily available to determine the mass partitioning for the converter and electrorefiner. However, because the metal product entering these furnaces has a higher content '
of copper than the metal entering the reverberatory furnace, the percentage of copper recovered is
. considered to be at least as great as that recovered for the reverberatory fumace. Therefore, for the converter, the same mass partitioning factors are used as for the reverberatory furnace. Very little dust and anode slime is produced during the electrorefining process because of the high purity of the anodes used in the process. Based on engineering judgement, partitioning to metal product is estimated to be as high as 98% for the electrorefiner. Partitioning to the anode slime and dust is estimated to be approximately 1% each.
' Personal communication between M. Anderson, SAIC and L Schuster, Cerro Copper Tube Company, May 27,1997.
3 Personal communication between M. Anderson, SAIC and G. Golebiowski, Muellar Copper Tube Company, May 27.1997.
5-7 Draft NUREG 1640, Vol. I t
Evaluation of Copper Section 5 5.3.2 Elemental Partitioning Factors l
Copper recycling involves three steps: a reverberatory furnace, a converter furnace, and an electrorefinery. For the first two furnaces the primary mechanism for impurity removal is oxidation. The first furnace, the reverberatory fumace, removes those impurities that are significantly greater in oxidation potential than copper, while the second, the converter, removes most elements with oxidation potential less than that of copper. In the third step, the electrorefiner, copper preferentia!!y plates out at the cathode while many impurities, such as lead and tin, are left in the anode slime. Nickel accumulates in the electrolyte. Extremely low concentrations af many impurities may be difficult to re;nove from the copper.
The elemental partitioning factors determined for the material flow model are intended to be representative of the expected behavior during melting beginning with a typical domestic reverberatory fumace. Direct thermodynamic calculations of the oxidation potential of each element were used in estimating elemental partition factors at temperatures typical of the reverberatory furnace and the converter. When these calculations were not possible, elemental partitioning factors were estimated based on the behavior of chemically similar elements. There is significant variability in the behavior of elements during copper refining depending on initial concentration, temperature of the melt, and the presence of chemically similar elements. Any single partitioning value used in the material flow model has some associated uncertainty. In order to address this uncertainty, ranges for the elemental partitioning values were used.
During refining, radionuclides could partition to one or both of the main melt components (i.e.,
the slag and metal phases) or discharge from the fumace in the volatilized gas. Some of the radionuclides that leave the furnace in the volatilized gas would remain in the vapor phase (off-gas) and some would condense or coalesce into particulates (dust). Radionuclides found in coarse particulates would be captured by the baghouse filter. Some of the fine particles and species in the vapor phase would escape in the off-gas exiting the stack.
Table 5.1 shows the resulting elemental partitioning factors (EPF) for each element. Note that the partitioning factors for some elements (e.g., iodine) do not sum to 100% since the values of the partitioning factors are estimated over a range.
5.4 Mathematical Model for Flow of Recycled Copper Scrap This section presents the equations that represent the information discussed previously in Section 5.2 and 5.3 and are used to formulate the mathematical model. The equations estimate radionuclide concentrations in refined copper and other co-products of refining. The equations are entered into spreadsheets that have been organized and structured specifically for this analysis. The calculated radionuclide concentrations in refined copper, refinery slag, refinery baghouse dust, and the amount of radioactivity released out the refinery stack are used as input to the scenario analyses.
Draft NUREG-1640, Vol.1 5-8 O
L
l l Section 5 Evaluation of Copper -
,^ Table 5.1 Elemental partitioning factor ranges (%) for copper refining Reverberatory Furnace
( Baghouse Element Matte Slag Dust Off-gas Cu 99-100 0.99-1.01 0 0
- Ag, Bi, Cd, Co, Cr, Fe, It, Mn, Mo, Nb, Ni, Pb, Sb 94-100 0.95-1.05 0 0 ;
Po,Re.Ru,Tc,Zr,69-100 0.7-1.3 0 0- i Zn 89-99 0.95-1.05 4.75-5.25 0 Ac, Am, Cm, Np, Pa, Pu, Th, U 0-5 95-100 0 0 P,S,Se 0-30 70-100 0 0 i
Ca,Cs,K,Na 0 94-100 0.95-1.05 0 Ba,Sr 35-65 35-65 0 0 Ce, Eu, Pm, Y, 19-31 56-94 0 0 Ra 19-31 19-31 0 0 C 0 38-62 0 71-100 1 0 59-100 0 0.6-1.4 Cl 0 30-70 29-69 0.9-1.1 H,Rn 0-5 0 0 95-100 Converter Blister Baghouse Element Copper Slag Dust Off-gas Cu 98-100 0.99-l.01 0 0 Ag, Ir 94-100 0.05-1.05 0 0 Bi, Co, Cr, Fe, Mn, Mo, Nb, Ni, Sb 9.5-10.5 86-94 0 0 Re,Ru,Tc,Zr 7-13 63-100 0 0 1 O
i Cd,Pb,Zn Po 9.5-10.5 9.5-10.5 0
0 86-94 63-100 0
0 Ac, Am, Cm, Pa, Np, Pu, Th, U 0-5 95-100 0 0 P,S,Sc 0-30 70-100 0 0 Ca, Cs, K, Na 0 94-100 0.95-1.05 0 Ba,Sr 35-65 35-65 0 0 Ce, Eu, Pm, Ra Y 19-31 56-94 0 0 C 0 3.8-6.2 0 71-100 1 0 59-10') 0 0.6-1.4 CI' 0 30-70 29-69 0.9-1.1 H,Rn 0-5 95-100 0 95-100 Electrorefiner Baghouse Element Copper Anode Slime Dust Off-gas Cu 99-100 0-1 0- 0 Ac, Ag, Am, Ba, Bi, Ca, Cd, Ce, Cm, Co, Cr, Cs, Eu, 0-1 99-100 0 0 Fe, Ir, K, Mn, Mo, Na, Nb, Ni, Np, Pa, Pb, Pm, Po, Pu, Ra, Re, Ru, Sb, Sr, Tc, Th, U, Y, Zn, Zr P,S,Se 0-5 70-100 0 0 C,H,Rn 0-5 0 0 95-100 1 0-20 0 0 80-100 Cl 0 0 38-62 38-62 b\
U 5-9 Draft NUREG 1640, Vol. I
I' Evaluation of Copper Section 5 5.4.1 Mixing of Cleared and Other Scrap l
l There are only two processes by which the original concentration of each radionuclide in cleared I copper scrap can be potentially changed. The first can occur upon mixing with other scrap metal !
I prior to refining. This mixing is a radionuclide-independent process, so the radioactivity concentration of all radionuclides is effected the same when mixing cleared copper scrap with a given mass of other copper scrap. The second process is the refining process itself, which generally consists of melting the copper scrap metal results in a redistribution (partitioning) of mass and radioactivity. Partitioning of mass during melting is radionuclide independent, however, partitioning of radioactivity during refining is element dependent. The following equations are used to calculate the concentrations in refinery co-products at those points in the material flow which corn.spond to potential exposure scenarios.
The following set of equations is used for all three steps used in copper refining (reverberatory furnace, converter fumace, and electrorefiner). Copper refining is a sequential process (except l
for the reflux from the converter, which is assumed to be steady state), so the calculated mass and j radioactivity concentrations in refined copper from the reverberatory furnace is used as input to ,
the converter furnace. Similarly, the output from the converter furnace is used as input to the !
electrorefiner.
(
I The total mass of material entering the furnace in a year, including cleared material, other scrap, j and primary metal was calculated using Equation 5.1.
M, = Mo+ M nc 51 where Mi = total mass of scrap metal entering the furnace per charbe (g/ charge) and
= mass of cleared material entering the furnace per charge (g/ charge)
Mo Msc = mass of other scrap metal entering the furnace per charge (g/ charge) l Mixing of cleared scrap with metal from sources other than licensed facilities can occur at the !
scrap dealer (i.e., secondary metal pool) and at the refinery, where material from the primary metal pool enters the furnace. In this analysis, no distinction is made between the two sources of 1 other metal. The mass of other metal includes contributions at the scrap yard and at the refinery.
The radionuclide concentration in the metal entering the furnace was calculated using Equation 5.2. The following equations are intended to be evaluated separately for each radionuclide in the analysis. Therefore, parameters such as concentration, decay factors, decay constants, and dose conversion factors are not explicitly subscripted for each radionuclide.
M C' =M, - C* 5.2 1 l
Draft NUREG-1640, Vol. I 5-10 1
TT' Section 5 Evaluation of Copper where C, =
radionuclide concentration in scrap entering the refining process (pCi/g)
=
Mo mass of cleared material entering the fumace per charge (g/ charge)
M, =
total mass of scrap m:tal entering the furnace per charge (g/ charge)
=
l C. original radionuclide concentration in cleared material (pCi/g) i For slag, baghouse dust, and off-gas, Equations 5.1 and 5.2 were evaluated using annual average l values for the masses of scrap entering the furnaces because all the exposure scenarios for these l materials depend on annual average concentrations. For metal, both an annual average and a single charge evaluation of Equations 5.1 and 5.2 were conducted. This was done for metal because there are metal products that could easily be manufactured from a single refinery charge.
The single charge concentrations were used in metal product-use exposure scenarios except where noted. (See Appendix D for additional details.)
5.4.2 Refinery Processes To accurately account for concentration changes in the different products, the mass of each l refinery product must be calculated. Equations 5.3,5.4, and 5.5 are used to calculate the masses of slag, dust, and metal product, respectively (no mass is associated with the completely volatilized elements). I M s= M, =f>, = CPY 5.3 p
lh M, M, =f,,
- CPY 5.4 M,, = M, =f,,
- CPY 5.5 Where M, =
mass of slag produced from a refinery per year (g/y)
=
M. mass of dust produced from a refinery per year (g/y)
M, = mass of metal product produced from a refinery per year (g/y) and Mi = total mass of scrap entering the furnace per charge (g/ charge) f,i = mass partitioning factor for slag during the refining process (dimensionless) fi = mass partitioning factor for dust during the rtfining process (dimensionless) f,i =
mass partitioning factor for metal product during the refining process (dimensionless)
CPY =
number of charges per refinery per year (charge)
The total amount of radioactivity in the original metal entering the furnace during the refining I process is partitioned among four product materials. Equation 5.6 shows the calculation for t
f
(
%/ )
5-11 Draft NUREG-1640, Vol. I
Evaluation of Copper Srction 5 radionuclide concentration in slag, taking into account both the mass and elemental partitioning factors.
C, . f, . M, C, f, C= = 5.6 f,,
M, f, where C, = radionuclide concentration in slag after the refining process (pCi/g) and C, = radionuclide concentration in scrap entering the refining process (pCi/g) f, = slag elemental partitioning factor during the refming process (dimensionless)
Mi = total mass of scrap entering the fumace per charge (g/ charge) f,i = mass partitioning factor for slag during the refining process (dimensionless)
The concentration of radionuclides in the dust and metal product are similarly calculated using Equations 5.7 and 5.8, respectively.
C, . f, C,= 5.7 dl where C, = radionuclide concentration in dust after tae refining process (pCi/g) and Ci = radionuclide concentration in scrap entering the refming process (pCi/g) f, = dust elemental partitioning factor during the refming process (dimensionless) foi
= mass partitioning factor for dust during the refining process (dimensionless)
C .fP C= 1 5.8 kt where C, = radionuclide concentration in metal product after the refming process (pCi/g) ]
Ci = radionuclide concentration in scrap entering the refining process (pCi/g) f, = metal product elemental partitioning factor during the refining process j (dimensionless) f,i = mass partitioning factor for metal product during the refining process (dimensionless)
No mass is explicitly calculated for the refinery off-gas. Exposure scenarios for atmospheric effluents are based on the total amount of radioactivity released from the refinery stack each ye'ar.
The annual amount of radioactivity in the off-gas was calculated using Equation 5.9.
Draft NUREG-1640, Vol.1 5-12 O
Section 5 Evaluation of Copper A, 4 C,
- M,
- f, . CPY 5.9 where A, = radioactivity in the off-gases leaving the refinery stack in a year (pCi/y) and C, = radionuclide concentration in scrap entering the refining process (pCi/g)
M, = total mass of scrap entering the furnace per charge (g/ charge) f, =
off-gas elemental partitioning factor during the refining process (dimensionless)
CPY = number of charges per refinery per year (charge) l Equations 5.10 and 5.11 are used to calculate the mass of dust that escapes the baghouse filters and the mass that is captured in the baghouse, respectively.
M,, = M, . ( 1 - BHg ) 5.10 where M,, =
total mass of dust that escapes the baghouse in a year (g/y) and l
/^ M, BH,y
=
=
mass of dust produced from the refining process in a year (g/y) baghouse efficiency (dimensionless)
('
where M, = M, - M,, 5.11 i
M,, = total mass of dust captured in the refinery baghouse in a year (g/y) and M. = mass of dust produced from the refining process in a year (g/y)
M,, = total mass of dust that escapes the baghouse in a year (g/y) 5.5 Radioactivity Concentrations in Copper Refining Co-products Mean radionuclide concentrations in the co-products from copper refining are listed in Tables 5.2 through 5.4 for each of the three refining steps. These values represent estimated radioactivity concentrations in the refinery output. The values are normalized to a unit radioactivity concentration in scrap and are only listed in S.I. units since the values are numerically identical if expressed in conventional units (e.g., pCi/g product per pCi/g scrap).
As stated above, Tables 5.2 through 5.4 list the mean concentration of each radionuclide in each medium. Tabulations are limited to mean values simply because of the space that would be required if percentiles from the distributions were also tabulated. The entire distribution of values' for each radionuclide in the appropriate medium was used as input for the exposure '
scenario analysis.
(V l-Draft NUREG-1640, Vol. I 5-13
Evaluation of Copper Section 5 l l
Table 5.2 Results of material flow model-copper reverberatory furnace Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
Refined Metal Off-gas Nuclide Single Charge Annual Slag Dust (Bq per Bq/g)
H-3 1.4 E-02 3.2E-04 0.0E+00 0.0E+00 3. l E+ 10 C-14 0.0E+00 0.0E+00 1.6E-02 0.0E+00 2.7E+ 10 Na-22 0.0E+00 0.0E+00 3.lE-01 1.6E-02 0.0E+00 P 32 1.3E-01 2.9E 03 2.7E-0! 0.0E+00 0.0E+00 S-35 1.3E-01 2.9E-03 2.7E-01 0.0E+00 0.0E+00 Cl-36 0.0E+00 0.0E+00 1.6E-01 8.0E-01 3.1 E+08 K-40 0.0E+00 0.0E+00 3.lE-01 0.0E+00 0.0E+00 Ca-41 0.0E+00 0.0E+00 3.lE-01 1.6E-02 0.0E+00 l Ca-45 0.0E+00 0.0E+00 3. l E-01 1.6E-02 0.0E+00 l Cr-51 8.4E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 I Mn-54 S.4E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 Fe-55 8.4 E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 q Co-57 8.4 E-01 1.9E ')2 3.lE-03 0.0E+00 0.0E+00 1 Co-58 8.4 E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Fe-59 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Ni-59 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Co-60 8.4 E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 Ni-63 8.4E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 Zn-65 8.lE-01 1.8 E-02 3.lE-03 8.2 E-02 0.0E+00 Cu-67 8.5E-01 1.9E-02 3.!E-03 0.0E+00 0.0E+00 Se-75 1.3 E-01 3.0E-03 2.7E-01 0.0E+00 0.0E+00 l Sr-85 4.3 E-01 9.6E-03 1.6E-01 0.0E+00 0.0E+00 Sr-89 4.3 E-01 9.6E-03 1.6E-01 0.0E+00 0.0E+00 Sr-90 4.3E-01 9.6E-03 1.6E-01 0.0E+00 0.0E+00 Y-91 2.2E-01 4.8E-03 2.3E-01 0.0E+00 0.0E+00 Mo-93 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Nb-93m 8.4E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 Nb-94 8.4 E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Nb-95 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Zr-95 7.3E-01 1.6E-02 3.lE-03 0.0E+00 0.0E+00 Tc-99 7.3 E-01 1.6E-02 3.lE-03 0.0E+00 0.0E+00 Ru-103 7.3E-01 1.6E-02 3.1E-03 0.0E+00 0.0E+00 Ru-106 7.3 E-01 1.6E-02 3.lE-03 0.0E+00 0.0E+00 Ag-108m 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Cd-109 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Ag-110m 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 Sb-124 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 1-125 0.0E+00 0.0E+00 2.5E-01 0.0 E+00 3. l E+08 Sb-125 8.4E-01 1.9E-02 3.lE-03 0.0E+00 0.0E+00 1-129 0.0E+00 0.0E+00 2.5E-01 0.0E+00 3.lE+08 I-131 0.0E+00 0.0E+00 2.5E-01 0.0E+00 3. l E+08 Ba-133 4.3 E-01 9.6E-03 1.6E-01 0.0E+00 0.0E+00 Cs-134 0.0E+00 0.0E+00 3.lE-01 1.6E-02 0.0E+00 Draft NUREG-1640, Vol.1 5-14
Section 5 Evaluation of Copper l Table 5.2 Results of materisi flow model -copper reverberatory furnace l . (Up) Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
Refined Metal Off-gas Nuclide Single Charge Annual Slag Dust (Bq per Bq/g)
Cs-137 0.0E+00 0.0E+00 3.lE-01 1.6E-02 0.0E+00 Cc-141 2.2E-01 4.8E-03 2.4E 01 0.0E400 0.0E+00 l Cc-144 2.2E 01 4.8E-03 2.3E-01 0.0E+00 0.0E+00 l Pm 147 2.2E-01 4.8E-03 2.4E-01 0.0E+00 0.0E+00 Eu 152 2.2E-01 4.8 E-03 2.3 E-01 0.0E+00 0.0E+00 Eu-154 2.2E-01 4.8E-03 2.4E-01 0.0E+00 0.0E+00 Eu-155 2.2E-01 4.8E-03 2.4E-01 0.0E+00 0.0E+00 Re-186 7.3 E-01 1.6E-02 . 3.2E-03 0.0E+00 0.06+00 Ir-192 8.4E-01 1.9E-02 3.lE 03 0.0E+00 0.0E+00
- Pb-210 8.4E-01 1.9E 02 3.lE-03 0.0E+00 0.0E+00 Po-210 7.3E-01 1.6E-02 3.2E-03 0.0E+00 0.0E+00 l Bi 210 8.4E-01 1.9E-02 3.1E-03 0.0E+00 0.0E+00 Rn-222 1.4E-02 3.2E-04 0.0E+00 0.0E+00 3.lE+10 Ra-223 2.2E-01 4.8E-03 7.8E-02 0.0E+00 0.0E+00 Ra-224 2.2E 01 4.8E-03 7.8E-02 0.0E+00 0.0E+00 Ac-225 1.4E-02 3.2E-04 3.lE-01 0.0E+00 0.0E+00 Ra 225 2.2 E-01 4.8E-03 7.9E-02 0.0E+00 0.0E+00 Ra-226 2.2E-01 4.8E-03 7.8E-02 0.0E+00 0 0E+00 Ac 227 1.5E-02 3.3 E-04 3 lE-01 0.0E+00 0.0E+00 O Th-227 Th 228 Ra-228 1.4E-02 1.5E-02 2.2E-01 3.3E-04 3.2E-04 4.8E-03 3.lE-01 3.lE-01 7.8 E-02 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00 0.0E+00 Th 229 1,4E-02 3.3E-04 3.lE-01 0.0E+00 0.0E+00 Th-230 1.4E-02 3.2E-04 3.lE-01 0.0E+00 0.0E+00 Pa 231 1.4E-02 3.2 E-04 3.lE-01 0.0E+00 0.0E+00 Th-231 1.4E-02 3.2E-04 3.IE-01 0.0E+00 0.0E+00 Th-232 1.4 E-02 3.2E-04 3.1E-01 0.0E+00 0.0E+00 Pa-233 1.5E-02 3.2E-04 3.lE-01 0.0E+00 0.0E+00 U 233 1.5E-02 3.lE-04 3.lE-01 0.0E+00 0.0E+00 Th-234 . 1.4 E-02 3.1 E-04 3.1E-01 0.0E+00 0.0E+00 U-234 1.4E-02 3.1 E-04 3.1E-01 0.0E+00 0.0E+00 l U-235 1.5E-02 3.2E-04 3.1E-01 0.0E+00 0.0E+00 Np-237 1.5E-02 3.lE-04 3.lE-01 0.0E+00 0.0E+00 Pu 238 1.4E-02 3.1E-04 3.1 E-01 0.0E+00 0.0E+00 U-238 1.4E-02 3.3E 04 3.lE-01 0.0E+00 0.0E+00 Pu-239 1.4E-02 3.3E-04 3.lE-01 0.0E+00 0.0E+00 Pu-240 1.4 E-02 3.2E-04 3.1E-01 0.0E+00 0.0E+00 Pu 241 1.4 E-02 3.2E-04 3.IE-01 0.0E+00 0.0E+00 Am-241 1.4 E-02 3.3 E-04 3.1E-01 0.0E+00 0.0E+00 Cm 242 1.5E-02 3.lE-04 3.1E-01 0.0E+00 0.0E+00 Pu 242 1.4 E-02 3.2 E-04 3.1E-01 0.0E+00 0.0E+00 Cm-244 1.4 E-02 3.2E-04 3.lE-01 0.0E+00 0.0E+00 5-15 Draft NUREG 1640, Vol.1 l
l
)
i Evaluation of Copper Section 5 i l
Table 5.3 Results of material flow model-copper converter furnace Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
Nuclide Refined Metal Slag Dust H-3 5.7E-06 0.0E+00 0.0E+00 i C-14 0.0E+00 0.0E+00 0.0E+00 Na-22 0.0E+00 0.0E+00 0.0E+00 :
P 32 4.7 E-04 4.2E-02 0.0E+00 q S-35 4.7E-04 4.2E-02 0.0E+00 l Cl-36 0.0E+00 0.0E+00 0.0E+00 K-40 0.0E+00 0.0E+00 0.0E+00 Ca-41 0.0E+00 0.0E+00 0.0E+00 Ca-45 0.0E+00 0.0E+00 0.0E+00 Cr-51 2.0E-03 2.9E-01 0.0E+00 Mn-54 2.0E-03 2.9E-01 0.0 E+00 >
Fe-55 2.0E-03 2.9E-01 0.0E+00 Co-57 l
2.0E-03 2.9E-01 0.0E+00 Co-58 2.0E-03 2.9E-01 0.0E400 Fe-59 2.0E-03 2.9E-01 0.0E+00 Ni-59 2.0E-03 2.9E-01 0.0E+00 Co-60 2.0E 03 2.9E-01 0.0E+00 Ni-63 2.0E-03 2.9E-01 0.0E+00 l Zn-65 1.9E-03 0.0E+00 1.5E+00 Cu-67 2.0E-02 3.3 E-03 0.0E+00 Se-75 4.5E-04 4.2E-02 0.0E+00 Sr-85 5.lE-03 8.3 E-02 0.0E+00 Sr-89 5.IE-03 8.3 E-02 0.0E+00 Sr-90 5.lE-03 8.3E-02 0.0E+00 {
Y-90 1.3E-03 6.3 E-02 0.0E+00 j Y 91 1.3E-03 6.3E-02 0.0E+00 i Mo-93 2.0E-03 2.9E-01 0.0E+00 l Nb-93m 2.0E-03 2.9E-01 0.0E+00 Nb-94 2.0E-03 2.9E-01 0.0E+00 l Nb-95 2.0E-03 2.9E-01 0.0E+00 ;
Zr-95 1.7E-03 2.3 E-01 0.0E+00 l Tc-99 1.7E-03 2.3E-01 0.0E+00 l Ru-103 1.7E-03 2.3E-01 0.0E+00 l Ru 106 1.7E-03 2.3 E-01 0.0E+00 Ag 108m 1.9E-02 2.3 E-03 0.0E+00 Cd-109 2.0E-03 0.0E+00 1.6E+00 Ag I10m 1.9E-02 2.3E-03 0.0E+00 Sb-124 2.0E-03 2.9E-01 0.0E+00 1-125 0.0E+00 0.0E+00 0.0E+00 Sb 125 2.0E-03 2.9E-01 0.0E+00 1-129 0.0E+00 0.0E+00 0.0E+00 I-131 0.0E+00 0.0E+00 0.0E+00 Ba-133 5.lE-03 8.4 E-02 0.0E+00 Cs-134 0.0E+00 0.0E+00 0.0E+00 Cs-137 0.0E+00 0.0E+00 0.0E+00 Cc-141 1.3 E-03 6.3E-02 0.0E+00 Ce 144 1.3 E-03 6.3 E-02 0.0E+00 Pm 147 1.3 E-03 6.2E-02 0.0E+00 Eu 152 1.3E-03 6.2E-02 0.0 E+00 Draft NUREG-1640, Vol.1 5-16
Section 5 Evaluttion of Copper Table 5.3 Results of material now model-copper converter furnsee Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
\ Nuclide Refined Metal Slag Dust Eu 154 1.3E 03 6.2E-02 0.0E+00 Eu-155 1.3E 03 6.2E-02 0.0E+00 Re-I86 1.7E-03 2.3E-01 0.0E+00 Ir-192 2.0E-02 2.3 E-03 0.0E+00 Pb-210 2.0E-03 0.0E+00 1.5E+00 Po-210 1.7E-03 0.0E+00 1.2E+00 Bi-210 2.0E-03 2.9E-01 0.0E+00 Rn-222 5.3 E-06 0.0E+00 4.9E+08 Ra-223 1.3E-03 6.3E-02 0.0E+00 Ra-224 1.3E-03 6.3 E-02 0.0E+00 Ac-225 5.6E-06 5.4E-03 0.0E+00 Ra-225 1.3E 03 6.3 E-02 0.0E+00 Ra-226 1.3 E-03 6.3 E-02 0.0E+00 Ac-227 5.6E-06 5.4 E-03 0.0E+00 Th-227 6.lE-06 5.6E-03 0.0E+00 Th-228 6.1E-06 5.6E-03 0.0E+00 Ra-228 1.3E-03 6.3 E-02 0.0E+00 Th-229 6.lE-06 5.6E-03 0.0E+00 Th-230 6.1E 06 5.6E-03 0.0E+00 Pa 231 6.0E-06 5.6E-03 0.0E+00 Th-231 6.1E-06 5.6E-03 0.0E+00 Th-232 6.lE-06 5.6E-03 0.0E+00 A Pa-233 6.0E-06 5.6E-03 0.0E+00 U 233 5.8 E-06 5.5E-03 0.0E+00 Th 234 6.lE-06 5.6E-03 0.0E+00 U-234 5.8E-06 5.5E-03 0.0E+00 U-235 5.8E-06 5.5E-03 0.0E+00 Np 237 5.8E-06 5.4E-03 0.0E+00 Pu 238 5.7E-06 5.6E-03 0.0E+00 U 238 5.8 E-06 5.5E-03 0.0E+00 Pu-239 5.7E-06 5.6E-03 0.0E+00 Pu 240 5.7E-06 5.6E-03 0.0E+00 Pu 241 5.7E-06 5.6E-03 0.0E+00 Am-241 5.8E-06 5.5E-03 0.0E+00 ,
Cm-242 6.0E-06 5.5E-03 0.0E+00 ' '
Pu 242 5.7E-06 5.6E-03 0.0E+00 Cm 244 6.0E-06 5.5E-03 O.0E+00 NOTES:
- 1) All values are annual averages because single charge values are not needed for any scenarios.
- 2) Only one radionuclide is partitioned to off-gas, H 3, with an annual release of 5.02E+08 Bq per Bq/g scrap.
- 3) Radionuclides that have mean concentrations of zero for all refinery products have concentrations of 0 Bq/g in the matte input to the converter.
oV 5-17 Draft NUREG-1640, Vol. I
~
I Evaluation of Copper Section 5 Table 5.4 Results of material flow model---copper electrorefinery j Mean concentrations in refinery products (Bq/g product per Bq/g scrap) l Refined Metal Nuclide Single Charge Annual Slag H3 4.2E-06 9.5E 08 0.0E+00 C-14 0.0E+00 0.0E+00 0.0E+00 Na-22 0.0E+00 0.0E+00 0.0E+00 P-32 3.2E-03 6.6E-05 2.4E-02 S-35 3.2E-03 7.4E-05 2.4E-02 Cl-36 0.0E+00 0.0E+00 0.0E+00 K-40 0.0E+00 0.0E+00 0.0E+00 Ca-41 0.0E+00 0.0E+00 0.0E+00 Ca-45 0.0E+00 0.0E+00 0.0E+00 Cr 51 3.0E-04 6.9E-06 1.2E-01 Mn-54 3.1E-04 6.9E-06 1.2E-01 Fe-55 3.0E-04 6.7E-06 1.2 E-01 Co-57 3.0E-04 6.8 E-06 1.2E-01 Co-58 3.0E-04 6.8E-06 1.2E-01 Fe-59 3.0E-04 6.7E-06 1.2E-01 Ni-59 3.0E-04 6.7E-06 1.2 E-01 Co-60 3.0E-04 6.8E-06 1.2 E-01 Ni-63 3.0E-04 6.7E-06 1.2 E-01 Zn-65 2.9E-04 6.5 E-06 1.2 E-01 Cu-67 9.2E-01 2.0E-02 4. lE-03 Se-75 3.3 E-03 7.2E-05 2.4E-02 Sr-85 7.8 E-04 1.7E-05 3.lE-01 St 89 7.8E-04 1.7E-05 3. l E-01 Sr-90 7.8 E-04 1.7E-05 3.lE-01 Y-91 2.0E-04 4.3E-06 7.8E-02 Mo-93 3.0E-04 6.7E-06 1.2E-01 Nb-93m 3.0E-04 6.8E-06 1.2E-01 Nb-94 3.0E-04 6.8E-06 1.2E-01 Nb-95 3.0E-04 6.8E-06 1.2E-01 Zr-95 2.6E-04 6.0E-06 1.1E-01 Tc 99 2.6E-04 6.0E-06 1. l E-01 Ru-103 2.6E-04 5.7E-06 1.lE-01 Ru-106 2.6E-04 5.7E-06 1.lE-01 Ag-108m 2.9E-03 6.6E-05 1.2E+00 Cd-109 3.lE-04 6.7E-06 1.2E-01 Ag-11Om 2.9E-03 6.6E-05 1.2E+00 Sb-124 3.lE-04 6.8E-06 1.2E-01 1-125 0.0E+00 0.0E+00 0.0E+00 Sb-125 3.1 E-04 6.8E-06 1.2E-01 1129 0.0E+00 0.0E+00 0.0E+00 1-131 0.0E+00 0.0E+00 0.0E+00 Ba-133 7.7E-04 1.7E-05 3.lE-01 Cs-134 0.0E+00 0.0E+00 0.0E+00 Cs-137 0.0E+00 0.0E+00 0.0E+00 1
Ce-141 2.0E-04 4.4 E-06 7.8E-02 Ce-144 2.0E-04 4.4 E-06 7.8E-02 j Pm-147 1.9E-04 4.4E-06 7.8E-02 Eu-152 1.9E-04 4.4E-06 7.8 E-02 Draft NUREG-1640, Vol.1 5-18
Section 5 Evaluation of Copper
(
g Table 5.4 Results of material flow model--copper electrorefinery Mean concentrations in refinery products (Bq/g product per Bq/g scrap)
Refined Metal Nuclide Single Charge Annual Slag Eu 154. l .9E-04 4.4 E-06 7.8E-02 Eu-l55 1.9E-04 4.4E 06 7.8E-02 Re-l 86 2.7E-04 5.9E-06 1.IE-01 Ir 192 3.0E-03 6.5E-05 1.2E+00 Pb-210 3.0E-04 6.9E-06 1.2E-01 Po-210 2.6E-04 5.8E-% l.IE-01 Bi-210 3.0E-04 6.7E-06 1.2E-01 Rn-222 4.1E-06 9.5E-08 0.0E+00 Ra-223 1.9E-04 4.3E-05 7.8E-02 Ra-224 1.9E-04 4.3E-06 7.8E-02 Ac-225 . 7.9E-07 1.9E-08 3.4E-04 Ra-225 1.9E-04 4.3E-06 7.8E-02 Ra-226 1.9E-04 4.3E-06 7.8E-02 Ac 227 7.9E-07 1.9E-08 3.4E-04 Th-227 9.2E-07 1.7E-08 3.3E44 Th 228 9.2E-07 1.7E-08 3.3 E-04 Ra-228 1.9E-04 4.3E-06 7.8 E-02 Th-229 9.2E-07 1.7E-08 3.3 E-04 Th 230 9.2E-07 1.7E08 3.3 E-04 Pa-231 9.2E-07 2.0E-08 3.6E-04 Th-231 9.2 E-07 1.7E-08 3.3E-04
{g Th-232 Pa-233 9.2E-07 9.2E-07 1.7E-08 3.3 E-04 2.0E-08 3.6E-04 U-233 8.6E-07 1.9E-08 3.5E-04 Th-234 9.2E-07 1.7E-08 3.3E-04 U-234 8.6E-07 1.9E-08 3.5E-04 U-235 8.6E-07 1.9E-08 3.5E-04 Np-237 8.9E-07 2.0E-08 3.4 E-04 Pu-238 7.6E-07 1.9E-08 3.4E-04 U 238 8.6E-07 1.9E-08 3.5E-04 Pu-239 7.6E-07 1.9E-08 3.4 E-04 Pu-240 7.6E-07 1.9E-08 3.4E 04 Pu 241 7.6E 07 1.9E.08 3.4E-04 >
Am 241 8.5 E-07 1.8E-08 3.3 E-04 Cm 242 8.5E-07 :2.0E-08 3.4E-04 Pu-242 7.6E-07 1.9E-08 3.4E-04 Cm-244 8.5E-07 2.0E-08 3.4 E-04 NOTES:
- 1) Only one radionuclide is partitioned to off-gas, H-3, with an annual release of 1.56E+06 Bq per Bq/g scrap.
- 2) Radionuclides that have mean concentrations of zero for all electrorefinery products have concentrations of 0 Bq/g in the blister input to the electrorefinery.
/%
I I V
I 5-19 Draft NUREG 1640, Vol.1
Evaluation of Copper Section 5 5.6 Dose Assessment for Unique Copper Recycle and Disposal Scenarios Most of the potential exposure scenarios for recycled and disposed copper scrap are adequately covered by adapting the steel scrap recycle scenarios described in Section 4. Only one scenario I was added to the copper analysis that was not already described: the use of copper or bronze piping made of recycled copper scrap. This general scenario was included in the evaluation of copper recycling because it represents a scenario unique to copper and because of the large amount of copper piping in use in the U.S. )
Recycled copper can be used to make piping or other plumbing fixtures. The additional scenario described below involves using copper or bronze piping made of recycled copper, where material that has leached from the piping into the drinking water might be ingested.
5.6.1 Exposure Pathways Ingestion: If copper pipe is used to transport water, a small amount of material could leach from the inside surface of the pipe to the water. If the water is used for drinking or cooking, the leached material could be ingested.
Suspension of particulates from copper piping is unlikely, therefore, the inhalation pathway is not included. Also, extemal exposure to copper pipes and fixtures was judged to be small in comparison to ingestion of drinking water and was not included in the modeling. '
5.6.2 Mathematical Representation The annual total effective dose equivalent (TEDE) is equal to the effective dose equivalent from the ingestion exposure pathway. The TEDE for a member of the public using copper or bronze piping is represented by Equation 5.12.
l l
DT*Oterg 5.12 l where Dr =
TEDE for the scenario (mrem /y) and D., = EDE due to ingestion (mrem /y)
Equation 5.13 calculates the radionuclide concentrations in the piping at the time use occurs.
This accounts for radioactive decay from the time the scrap is cleared frorn a nuclear facility to the time the scenario begins. The reference to " source material" in the parameters of Equation 5.13 and other equations means the material that represents the source of exposure. In this scenario, the source material is copper or bronze piping.
Draft NUREG-1640, Vol.1 5-20 O
p
, j L Section 5 Evaluation of Copper p '
Co C,e* 5.13 where
=
C. radionuclide concentration in the source material at time the scenario begins (pCi/g) and C, =
undecayed radionuclide concentration in the source material (pCi/g)
A = radioactive decay constant (1/d) l t, =
time from clearance from nuclear facility to time scenario begins (d) l This scenario includes the assumption that while water is transported through a copper or bronze i _ piping, a certain amount of piping material is leached from the pipe into the water. The dose due to this exposure pathway is presented in Equation 5.14.
D;,,,=C *CRCu o
- DIsy = Fsy = t,,
- DF,,,, * (l E -03 ) 5.14 where l D., = EDE due to irs 'stion (mrem /y) and
=
l C. radionuclide conumtration in the source material at time the scenario begins (pCi/g) crc, = leaching rate for copper (mg Cu/L water)
DI. =
total water intake (L water /d) l F, =
fraction of total water intake that is from the copper pipes (dimensionless) l DFa, ingestion dose factor (mrem /pCi intake) t IE-03 = unit conversion factor (g/mg) t,
= annual number of days of exposure for the scenario (d/y) l 5.7 Parameter Discussion for all Modeled Scenarios Calculation of potential impacts from recycle of cleared copper scrap material depends on many j parameter values. Parameter values are needed for both material flow and dose assessment i models. The material flow parameter values rely on infomiation from the U.S. secondary copper I
industry. The parameter values for the dose modeling are a function of receptor behavior, such as time on a specific job or breathing rate, as well as how the radionuclides are transported in the environment. The dose modeling parameter values are based on those used in the iron and steel modeling described in Section 4. Except for scenario timing assumptions, only those parameter values that are different from those used in the iron and steel modeling are discussed in this section.
Nominal parameter values are described below. Ranges were used to define some parameter values in the modeling. All values and ranges are given in Appendix B.
O V
5 21 Draft NURECr1640, Vol.1
(-
o
(
Evaluction of Copper Section 5 5.7.1 Scenario Timing This section presents the basic assumptions used in defining the time periods for each of the copper recycle scenarios. They are based on the scenatio timing for the basic oxygen furnace (BOF) iron and steel refinery modeling. The following list of basic assumptions was used in estimating the timing parameters for the scenarios:
Scrap Handling:
All cleared scrap metal is assumed to be initially taken to a scrap dealer. It takes 4 d ys for the scrap metal to reach the scrap dealer.
The scrap metal remains at the scrap dealer for a period of 7 days prior to reuse or disposal and 25 days for scrap metal that is recycled.
Refining and Processing:
For recycled scrap metal, the refining process and associated product manufacture, final processing, and any on-site storage at the refinery takes a total of 15 days for each of the reverberatory, converter, and electrorefinery facilities.
. The metal product output from the reverberatory and converter facilities immediately enters the converter and electrorefinery, respectively.
Following initial processing, reverberatory and electrorefinery products undergo further processing before use. This secondary processing, plus storage and handling takes 22 days.
. Distribution of products from the reverberatory and converter takes 7 days.
. Radionuclide releases into the atmospheric effluent from the reverberatory and converter occur at the time the scrap is refined, i.e.,29 and 44 days after clearance, respectively.
Use and Disposal:
. An electrorefinery metal product is used for 30 years, based on an assumed use in the construction industry. Use of a reverberatory metal product is 10 years, based on an assumed general purpose use (IAEA 1992). .
l
= Reverberatory, converter and electrorefinery slag and baghouse dust are produced at the time refining occurs,29,44, and 59 days, respectively, after clearance of scrap metal from a licensee.
Draft NUREG-1640, Vol. I 5-22 O
l
.. _ _--------_______------------------------_-J
Section 5 Evaluation of Copper a
Refinery clag that is sold for subsequent use is processed at the refinery 3 days after
, (oD) production and leaves the refmery in another 2 days. Slag is used within 2 days after i distribution and is used for a period of 30 years. Once the period of use is completed, the !
products are disposed ofin a sanitary landfill. Slag that is to be directly disposed is held at the refinery for 7 days, at which time it is transported to a disposal facility. The slag is assumed to be disposed'immediately following handling at a sanitary landfill.
Baghouse dust from the reverberatory, converter, and electrorefinery is disposed of onsite or sent to a sanitary disposal facility after 7 days. Storage and handling takes 4 days, at which time disposal occurs.
5.7.2 Dose Evaluation This section presents a discussion of parameter values used for the analysis of copper recycle ,
scenarios. In general, the same scenarios are analyzed for copper recycle as were analyzed for steel recycle in Section 4. Values used for many of the parameters are also the same as for the
, steel recycle analysis. For some parameters, however, values specific to the recycle of copper were used in order to more appropriately model the scenarios as they would likely occur for i copper recycle. The following discussion is limited to these specific parameter values. If a '
parameter is not discussed below and listed in Table B.9, the same value as used for the steel evaluation (Table B.7) is used for copper.
( 5.7.2.1 Input Concentrations from the Material Flow i
A The undecayed radionuclide concentration in the source material, C,, is used as the source material input radionuclide concentration for scenario evaluations. This parameter is radionuclide dependent and is calculated in the material flow modeling. Table B.11 lists the sources for C,, as they appear in the mathematical modeling of the material flow (e.g., C,,
concentration in metal product after the refining process).
5.7.2.2 External Exposure Parameters This section describes the value used for one parameter needed for calculating extemal exposure including those that address duration of exposure and material density. Values for these parameters are tabulated in Table B.9.
For the scrap disposal scenario a fixed value of 4.47E+6 g/m3 is used for the density of waste, consistent with the value used in the calculation of the geometry factors for metal products.
5.7.2.3 Ingestion Exposure Parameters This section describes the values used for those unique parameters needed for calculating ingestion exposure.
3 (O
5-23 Draft NUREG-1640, Vol. I
Evaluation of Copper Section 5 The use of copper or bronze pipes can increase the concentration of copper in drinking water.
When water is allowed to remain in the pipes for a period of time copper can teach from the pipes into the water. Soft water is more corrosive than hard water, therefore enhancing leaching of copper from the pipes (U.S. Public Health Services 1990). When pipes have not been flushed after a period of disuse, the concentration of copper in tap water may exceed 1.3 ppm (1.3 mg Cu/L water), which is the EPA drinking-water limit (U.S. Public Health Services 1990). U.S.
Public Health Services (1990) presents results from a number of different studies. One study in Canada found that the copper concentration in treated water that has not been exposed to copper pipes was generally very low, s 10 ppb (0.01 mg Cu/L water). Another study in Seattle, WA showed the mean copper concentrations in running and standing water from copper pipes were 0.16 and 0.45 ppm, respectively, with an average value of 0.31 ppm (0.31 mg Cu/L water), and an increase in copper concentration due to leaching of copper from the pipes of 0.3 mg Cu/L water. A triangular distribution, with a minimum of 0.16 mg Cu/L, a most likely value of 0.3 mg Cu/L, and a maximum of 1.3 mg Cu/L is used to represent the variation in observed data for the parameter CRo , the concentration of copper in tap water due to leaching from pipes.
Analysis of survey data has shown that tap water averages about 60% of total water consumption (Roseberry and Burmaster 1992). This analysis supports a lognormal distribution for total tap water consumption having a geometric mean of 1400 ml/d and a geometric standard deviation of 1.78. In addition, not all tap water consumption comes from one's own tap. A significant number of meals are eaten outside one's home, for example. The data on the fraction of tap water from one's own tap are poor and are best represented by a uniform distribution having a minimum of 0.5 and a maximum of 1.0.
5.7.2.4 Atmospheric Release Parameters The only parameter value for atmospheric dispersion of refinery stack releases from copper recycling facilities that is different from the steel analysis is the total mass of dust that escapes the refinery baghouse in a year, Mm . This value is calculated in the material flow model, and values of 3.31E+06 g and 3.08E+06 g were calculated for the reverberatory and converter, respectively.
The surface-to-mass ratios of various objects (spheres) were examined in estimating values for 2
this parameter for copper. Copper objects are assumed to have a density of 9.0 g/cm . Values 2
for various copper objects ranges from approximately 0.01 cm /g for large-radius spheres, wire, and bar stock, up to approximately 2.2 for small radius spheres and thin sheets and pipes.
Data are not available to provide an adequate basis for choosing a "best estimate" from this range of values. Using professionaljudgement and these theoretical data, the value of the parameter SM for recycled copper scrap is best described by a loguniform distribution having a minimum of 0.2 cm2 /8and a maximum of 2.0 cm 2/g. The minimum value is characteristic of heavy wire having a radius of 0.5 cm. The maximum value is characteristic of pipes and sheets having a thickness of 0.05 cm. The range for copper is representative of wire, pipes, and sheets of various sizes with residual radioactivity on one side only. A wide variety of copper and copper alloy j
Draft NUREG-1640, Vol. I 5-24 9
E Section 5 Evaluation of Copper p (brass and bronze) objects commonly found at nuclear facilities have surface to-mass values that t fall within this range.
L This range can be compared to an estimate from a studies similar to this one. O'Donnell (1978) suggested a generic value of 0.6 cm2 /g as representative of Number 2 copper wire, and O'Donnell's calculations are based on a reference copper object with a surface-to-mass ratio of 0.45cm2fg, 5.8 Dose Factors for Recycle and Disposal of Copper Scrap This analysis of recycled cleared copper scrap includes 23 separate scenarios evaluated for 85 radionuclides. Figure 5-2 shows which scenarios describe the critical groups and for how many radionuclides. There are six scenarios which have the highest dose factor for at least one
' radionuclide. The largest number of radionuclides have critical groups described by scenarios associated with transporting (47 radionuclides) or handling (I radionuclide) unprocessed scrap.
Individuals handling either reverberatory furnace, converter, or electrorefiner slag constitute the critical group for 31 radionuclides. For four volatile radionuclides, the critical group consists of individuals exposed to atmospheric releases from the refining process. Transporting baghouse dust describes the critical group for one radionuclide. Only one radionuclide is limited by a scenario associated with use of a consumer product made from refined copper. Table 5.5 lists the mass-based critical-group dose factors for each radionuclide. Table 5.6 lists the corresponding derived surficial dose factors for each radionuclide. Results for all 23 copper scenarios are n tabulated in Appendix G.
The mean values of the critical-group dose factors for each radionuclide are listed in Table 5.5 as the " critical-group dose factor." These represent the dose to the average member of the critical group exposed to radioactivity distributed throughout the mass of cleared copper (Bq/g or pCi/g).
The circumstances of that exposure are described by the scenario indicated in the right hand column. The 5*,50*, and 95* percentiles listed for each radionuclide represent the underlying distribution of dose factors calculated for each critical group. The range of values from the 5* to the 95* percentile is the 90% confidence interval on the dose factor. That is, there is a 90%
certainty that the dose factor for the average member of the critical group lies within this interval.
The confidence interval is a subjective measure of uncertainty in the dose factor that includes estimates of the variability and uncertainty in the parameters used in each scenario.
The ratio of the 95* to the 5* percentile is a useful measure of the relative width of the 90%
confidence interval for comparison between scenarios. Smaller values of the 95/5 ratio indicate less uncertainty than larger values. The scenarios with the smallest uncertainty are those with the fewest number of exposure pathways and the least uncertainty in the parameters describing those pathways. The scrap transportation scenario accounts for 47 of the 85 radionuclides. It has the smallest uncertainty of all the critical group scenarios with a 95/5 ratio of about 2 for most
)
5 25 Draft NUREG 1640, Vol.1
Evaluation of Copper Section 5 50 . -. . . . .
45 Ed _ _ . _ _ _ _ , _ _ ___ _ , . _ _ . _ _ ,
g.
9E p .,
40 Copper Critical Group Scenarios
// Ad. j vv !
!$)h 3 5 . ._ _ . _ _ . _ _ _ _ _ . _ _ . _ _ . . , _ _ _
5 9$y j -
6$ giil 9 ?)Et 1 25 3
w .
e
^:
o e. . s n E 20- * .
, k
's-M
?da s
W.fi 10 - .h}
.a .-
5- ?' f.
..~' .
1 1 1
^lb @ &;. 3 m m n
/ // / / / / O
, /
Figure 5.2 Scenarios describing critical groups for copper recycle radionuclides. The sources of uncertainty in this scenario are similar to those for the steel scrap transportation scenario discussed in Section 4.9.
For all scenarios that take place subsequent to the initial transport of scrap, additional sources of uncertainty are introduced and wider confidence intervals result. Scenarios that address handling of scrap include uncertainty due to mixing with other scrap. They also include additional exposure pathways - inhalation of resuspended dust and inadvertent ingestion under dusty conditions. Scenarios that address handling and processing of refinery products such as baghouse dust and refinery slag include additional uncertainty in how much of each radionuclide is partitioned to these materials. For copper, this group of handling and processing scenarios have 95/5 ratios that range from about 10 to about 20.
Draft NUREG-1640, Vol.1 5-26 O
p ,
Section 5 Evaluation of Copper i
l 1
Table 5.5 Copper recycle critical-group dose factors-mass
!.p\
( (pSv/y per Bq/g) (mrem /y per pCi/g) '
Gl g; 90% Confidence interval 90% Confidence interval g ,
l group 5* 50* 95* group 5* 50* 95*
- dose (lower (median) (upper dose (lower (median) (upper ,
l Radionuclide factor bound) bound) factor bound) bound) Scenario 1 H-3 5.6E-04 6.lE-05 4.lE-04 1.7E-03 2.lE-06 2.2E-07 1.5E-06 6.2E-06CU.ATMO.REVERAT-N C-14 1.6E-02 1.7E-03.1.lE-02 5.lE-02 6.0E-05 6.4E-06 4.0E-05 1.9E-04CU-ATMO-REVERAT-N Na-22 2.2E+02 1.4E+02 2.2E4 C2 3.1E+02 8.1E-01 5.lE-01 8.1E-01 1.1E+00CU-SCRP-TRANSPO-W I P-32 1.3E-01 8.2E-02 1.3E-01 1.8E-01 4.8E-04 3.0E-04 4.8E 04 6.8E-04CU-SCRP-TRANSPO-W Cl-36 d* --- .
3 fk k b 5.2E-02 4.6E-03 3.4E-02 1.6E-01 1.9E-04 1.7E-05 1.3E-04 5.8E-04CU-ATMO-REVERAT-N i K-40 1.6E+01 1.0E+01 1.6E+012.3E+01 6.0E-02 3.8E-02 6.0E 02 8.4E-02CU-SCRP-TRANSPO-W Ca-41 2.0E-03 3.3E-04 1.5E-03 5.2E-03 7.3E-06 1.2E-06 5.6E-06 1.9E-05CU REVS-HANDLIN.W Ca-45 5.lE-03 1.0E-03 3.8E-03 1.3E-02 1.9E-05 3.8E-06 1.4E-05 5.0E-05CU-REVS-HANDLIN-W
.~r 97 ~w m. - - - . - - - , ~ . . ,
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5-27 Draft NURG.1640, Vol. I
Evaluation cf Copper Section 5 Table 5.5 Copper recycle critical-group dose factors-mass (pSv/y per Bq/g) (mrem /y per pCi/g) l g 90% Confidence interval 90% Confidence interval g
group 5* 50* 95* group 5* 50" 95* l dose (lower (rnedian) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag-il0m 2.8E+02 1.8E+02 2.8E+02 4.0E+02 1.0E+00 6.6E-01 1.0E+00 1.5E+00CU-SCRP-TRANSPO-W j Sb-124 1.8E+02 1.2E+02 1.8E+02 2.5E+02 6.7E-01 4.3E-01 6.7E-01 9.4E-01 CU-SCRP-TRANSPO-W 1-125 6.5E-02 4.2E-02 6.5E-02 9.lE-02 2.4E-04 1.5E-04 2.4E-04. 3.4E-04CU-SCRP TRANSPO-W Sb-125 4.l E+01 2.6E+01 4. l E+01 5.7E+0 ! 1.5E-01 9.5E-02 1.5E-01 2. lE-01 CU-SCPS-TRANSPO-W l
- h. b h 34 h F3 h I-131 2.5E+01 1.5E+012.5E+013.6E+01 9.3E-02 5.5E-02 9.lE-02 1.3E-OlCU-SCRP-TRANSPO-W Ba-133 2.8E+01 1.8E+01 2.8E+01 3.9E+01 1.0E-01 6.5E-02 1.0E-01 1.4E-01 CU-SCRP-TRANSPO-W Cs-134 1.6E+02 1.0E+02 1.6E+02 2.2E+02 5.9E-01 3.7E-01 5.9E-01 8.3E-01 CU-SCRP-TRANSPO-W Cs-137 6.2E+01 3.9E+01 6.2E+01 8.6E+01 2.3E-01 1.4E-01 2.3E-01 3.2E-01 CU-SCRP-TRANSPO-W
~.m,.wy - - ,-, _ n . m..w ,- ~ r., - w n . , .m ~.,. - m Q$M132._7E+00 --- -,?D7E400.2.7E40J0.8E400 p l;.0E-023,61E-0,3fil .0E,-02E1.4 ,._ _-SCRP,-MijSPO-yy Ce-144 3.3E+00 2.lE+00 3.3E+00 4.6E+00 1.2E-02 7.7E-03 1.2E-02 1.7E-02CU-SCRP-TRANSPO-W Pm 147 6.8E-03 1.5E-03 5.2E-03 1.7E-02 2.5E-05 5.5E-06 1.9E-05 6.2E-05CU-REVS-HANDLIN-W Eu-152 1.lE+02 7.0E+01 1.lE+02 1.6E+02 4.lE-01 2.6E-01 4.lE-01 5.8E-01 CU-SCRP TRANSPO-W l Eu-154
-,m. 1.2E+02 7.6E+01 1.2E+02
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, .. m - 6.3E-01
-m CU .SCRP-TRANSPO-W
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Ir-192 7.lE+01 4.5E+01 7.lE+01 9.9E+0! 2.6E-01 1.7E-01 2.6E-01 3.7E-Ol CU-SCRP-TRANSPO-W l Pb-210 7.7E-01 2.8E+00 9.2E+00 9.2E+00 1.4E-02 2.8E-03 1.0E-02 3.4E 02CU-ELRS-HANDLIN-W Po-210 2.0E-01 7.7E-01 2.6E+00 2.6E+00 3.9E-03 7.6E-04 2.8E-03 9.7E-03CU-ELRS-HANDLIN-W
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[6 M j k h [ h [ M M Draft NUREG-1640, Vol. I 5-28 j l
1
)
F l.
l' Section 5 Evaluation of Copper l
m, Table 5.5 Copper recycle critical-group dose factors-mass
.f 1 (pSv/y per Bq/g) (mrem /y per pCi/g)
'd l 90% Confidence interval 90% Confidence interval Csial- gg, l group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Pa-233 1.3E+01 8.4E+00 1.3E+01 1.8E+01 4.9E-02 3.lE-02 4.9E-02 6.8E-02CU-SCRP-TRANSPO-W U-233 2.5E+014.8E+00 2.0E+0! 6.2E+01 9.3E-02 1.8E-02 7.2E-02 2.3E-01CU-RF.VS-HANDLIN-W Th-234 7.3E-01 4.6E 01 7.3E-01 1.0E+00 2.7E-03 1.7E-03 2.7E-03 3.8E-03CU-SCRP-TRANSPO-W U-234 2.5E+01 4.3E+00 1.9E+01 6.6E+0i 9.2E-02 1.6E-02 7.0E-02 2.5E-01 CU-REVS-HANDLIN-W Np-237 kbhb 1.lE+02 2.lE+018.3E+013.2E+02 4.!E-01 7.9E-02 3.lE-01 1.2E+00CU-REVS-HANDLIN-W i Pu-238 5.5E+01 9.7E+00 4.lE+01 1.5E+02 2.0E-01 3.6E-02 1.5E-01 5.7E-01 CU-REVS-HANDLIN-W j U-238 2.3E+014.0E+001.6E+016.4E+01 8.5E-02 1.5E-02 5.9E-02 2.4E-01CU-REVS-HANDLIN W Pu 239 5.8E+01 1.0E+014.4E+01 1.5E+02 2.2E-01 3.8E-02 1.6E-01 5.6E-01 CU-REVS-HANDLIN-W
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5-29 Draft NUREG 1640, Vol. I
F Evaluation of Copper Section 5 Table 5.6 Copper recycle critical-group dose factors-surficial (pSv/y per Bq/cm2 ) (mrem /y per pCi/cm2) 90% Confidence interval 90% Confidence interval Critical- Cn. .tical-group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper '
i Radionuclide factor bound) bound) factor bound) bound) Scenario H-3 4.8E-04 4.5E-05 3.3E-04 1.4E-03 1.8E-06 1.7E-07 1.2E-06 5.0E-06CU-ATMO-REVERA f-N C-14 1.4E-02 1.3E-03 8.4E-03 4.6E-02 5.lE-05 4.6E-06 3.lE-05 1.7E-04CU-ATMO-REVERAT-N Na-22 1.9E+02 9.3E+01 1.8E+02 3.2E+02 7.0E-01 3.4E-01 6.5E-01 1.2E+00CU-SCRP-TRANSPO-W P-32 1.lE-01 5.4E-02 1.0E-01 1.9E-01 4.lE-04 2.0E-04 3.9E-04 6.9E-04CU-SCRP-TRANSPO-W hhbM4.4E-02 4.5E-03 2.8E-02 1.3E-01 Cl-36
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r Secti:n 5 Evaluation of Copper
.l Table 5.6 Copper recycle critical-group dose factors-surficial
~
r (pSv/y per Bq/cm2) (mrem /y per pCi/cm:) ;
g; 90% Confidence interval 90% Confidence interval g l group 5* 50* 95* group 5* 50* 95*
dose (lower (median) _ (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag-110m 2.4E+021.2E+02 2.2E+02 4.2E+02 8.9E-01 4.4E-01 8.3E-01 1.5E+00CU-SCRP-TRANSPO-W Sb-124 1.5E+02 7.6E+01 1.4E+02 2.6E+02 5.7E-01 2.8E-01 5.3E-01 9.7E-01 CU-SCRP-TRANSPO-W I 125 5.6E-02 2.7E-02 5.2E-02 9.5E-02 2.lE-04 1.0E-04 1.9E-04 3.5E-04CU-SCRP-TRANSPO-W Sb-125 3.5E+01 1.7E+01 3.2E+01 6.0E+01 1.3E-01 6.4E-02 1.2E-01 2.2E-Ol CU-SCRP-TRANSPO-W b h ~
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5-31 Draft NUREG-1640, Vol. I j
Evtlu: tion of Copper S:ction 5 Table 5.6 Copper recycle critical-group dose factors-surficial (pSv/y per Bq/cm:) (mrem /y per pCi/cm2 )
i 90% Con 0dence interval 90% Con 0dence interval Critical- gg, group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Pa-233 1.lE+0! 5.5E+001.lE+0i 1.9E+01 4.2E-02 2.0E-02 3.9E-02 7.0E-02CU-SCRP-TRANSPO-W U-233 2. lE+01 4.0E+00 1.6E+01 5.5 E+01 7.9E-02 1.5E-02 5.8E-02 2.2E-01CU-REVS-HANDLIN-W Th-234 6.2E-01 3.0E-01 5.8E-01 1.0E+00 2.3E-03 1.lE-03 2.2E-03 3.9E-03CU-SCRP-TRANSPO-W U-234 2. l E+01 3.4E+00 1.5E+01 6. lE+01 7.9E-02 1.2E-02 5.5E-02 2.3E-01CU-REVS-HANDLIN-W h bf kb$kkb kk 1 b h -b h b i Np-237 9.4E+01 1.6E+01 6.6E+01 2.7E+02 3.5E-01 5.9E-02 2.4E-01 1.0E+00CU-REVS-HANDLIN-W Pu-238 4.8E+01 7.lE+00 3.4E+01 1.3E+02 1.8E-01 2.6E-02 1.2E-01 4.9E-01 CU-REVS-HANDLIN-W U-238 2.0E+01 3.0E+00 1.4E+01 5.8E+0 ! 7.3E-02 1.lE-02 5.lE-02 2.lE-01CU-REVS-HANDLIN-W Pu-239 5.0E+01 8.4E+00 3.6E+01 1.4E+02 1.9E-01 3.lE-02 1.3E-01 5.2E-01 CU-REVS-HANDLIN-W
+0119:0Eg3Mhhh [1}Il[3M0$hMkhhkh[ LEE [
Pu-241 8.lE-01 1.3E-01 5.7E-01 2.5E+00 3.0E-03 4.7E-04 2.lE-03 9.3E-03CU-REVS-HANDLIN W j Am-241 7.8E+01 1.4 E+01 5.5 E+01 2. l E+02 2.9E-01 5.l E-02 2.0E-01 7.9E-01 CU-REVS-HANDLIN-W Cm-242 2.5E+00 5.0E-01 1.9E+00 6.9E+00 9.4E-03 1.8E-03 6.9E-03 2.6E-02CU-REVS-HANDLIN-W Pu-242 4.6E+01 8.0E+00 3.2E+01 1.2E+02 1.7E-01 2.9E-02 1.2E-01 4.3E-01 CU-REVS-HANDLIN-W j Cm-244 4.2E+01 7.4E+00 3.lE+01 1.lE+02 1.5E-01 2.7E-02 1.lE-01 4.2E-01 CU-REVS-HANDLIN-W j Greater uncertainty is associated with scenarios that involve multiple exposure pathways and complex submodels. Four volatile radionuclides (H-3, C-14, Cl-36, and I-129) have critical groups consisting ofindividuals living in the vicinity of a copper refinery and exposed to atmospheric releases. This scenario includes an atmospheric dispersion model and pathways for ingestion, inhalation, and external exposure, each of which contributes to uncertainty in the dose factor. For copper, radionuclides limited by the atmospheric release scenario have 95/5 ratios that range from about 30 to about 35. Most of this uncertainty is due to the atmospheric dispersion model but additional contributions from partitioning to refinery off-gas and .
uncertainties in ingestion dose are nuclide-dependent. !
The mean values of the derived surficial dose factors for each radionuclide in Table 5.6 represent the dose to the average member of the critical group exposed to radioa.ctivity initially distributed ,
2 over the surface cleared copper scrap (Bq/cm or pCi/cm2 ). Derived surficial dose factors are ,
calculated from mass-based dose factors by use of a surface-to-mass ratio, SM, appropriate for typical copper objects available for clearance. The use of this parameter to derive surficial dose ;
! factors is described in Section 4.7. !
1
! l l The calculation of derived surficial dose factors is probabilistic. The parameter SM is j l
represented by a distribution of values that incorporate the variability and uncertainty in the i surface-to-mass ratio of typical copper objects available for clearance. This additional source of uncertainty results in wider confidence intervals for the surficial dose factors than for the mass- !
\
Draft NUREG 1640, Vol.1 5-32 !
i
Section 5 Evaluation of Copper
, based dose factors from which they are derived. The relative importance of this additional t uncertainty depends on the scenario. For scenarios with the narrowest' confidence intervals, the l k added uncertainty can contribute as much as an additional 50% to the width of the confidence interval. The mass-based dose factor for the scrap transportation scenario has a 95/5 ratio of about 2 for most radionuclides. The corresponding derived surficial dose factors have a 95/5 ratio of about 3 The added uncertainty in surthce-to-mass ratio has a relatively smaller impact on the confidence interval for scenarios with larger uncertainties, contributing an additional 10%
to 30%.
l O U O 5-33 Draft NUREG 1640, Vol.1 l
6 EVALUATION OF RECYCLE AND DISPOSAL OF ALUMINUM SCRAP V( Seventeen potential ext'osure scenarios for cleared aluminum scrap that are realistically based on current American industries are evaluatedin this section. As in the steel evaluation, scenario categories include handling and processing, storage, transportation, product use, and disposal. A radionuclide-speciRc, probabilistic dose factor distribution was calculated for the members of all exposed groups, and dose factors for an average member of each critical group was calculated in the same manner as for steel recycle. The mean dose factor for each critical group is reported in normalized units ofpSv4 per Bq/g scrap (mrem & perpCi/g) and pSv& per Bq/cm' scrap (mrem /y per pCi/cm') for each radionuclide. Dose factors at the 5*, 50*, and 95* percentiles are also reported.
Similar to steel and copper, the most common critical group consists of commercial truck drivers carrying cleared aluminum scrap. Scenarios involving transport of scrap material resulted in cntical i group designation for overhalf(52) of the 85 radionuclides in the analysis. Other scenarios identifying critical groups for many radionuclides involve handling aluminum scrap material (17 radionuclides).
Unlike the other metals evaluated, use of aluminum products identify critical groups for several radionuclides. Use of aluminum cookware accounts for 11 criticalgroups, and use of a generic, small metal object accounts for 2 critical groups.
Mean cntical-group dose factors range from a high of 6 pSvh per Sq/g (0.02 mrem /y perpCi/g) for Ag- l 110m to a low of 2E-06 pSv4per Bq/g (TE-09 miem& per pCi/g) for H-3. The surficial mean critical- l' group dose factors range from 23 pSvh per Bq/cm' (Ag-110m) down to 7E-06 pSv/y per Bq/cm (H-3).
Scenarios involving scrap transport account for the highest critical-group dose factors. Seventy-eight of the radionuclide-specific, mean dose factors for aluminum critical groups are 270 pSv/yper Bq/g or lower (1 mrem &perpCilg). l f
V This section describes the technical evaluation of the recycle and disposal of aluminum scrap that could be cleared from Nuclear Regulatory Commission (NRC) licensed facilities. Similar to steel scrap (Section 4), the flow of cleared material was probabilistically modeled, distributions of radionuclide concentrations in refined and disposed materials were calculated, and the mean dose factors for each potentially exposed group were estimated.
6.1 Introduction to Analysis The analysis process for potential exposures from aluminum recycle and disposal is essentially the same as described previously for stect and copper. A material flow model specific to aluminum scrap was developed, radionuclide concentrations were calculated, and scenario evaluations were conducted. Besides the material flow model (and calculated concentrations in refined and disposed materials), there are only mmor differences between the steel and aluminum scrap analyses. There are several minor scenario parameter differences and one additional exposure scenario that is specific to recycled aluminum scrap (described in Section 6.6).
6.2 Flow of Recycled and Disposed Aluminum Scrap The material flow model for aluminum represents the general processes that cleared material would go through from the time it is cleared by a licensed facility to the time of final O 6-1 Draft NUREG-1640, Vol. I
Evaluation of Aluminum Sectica 6 disposal. Similar to steel and copper, the aluminum material flow model is comprised of two types of models: conceptual and mathematical. The conceptual model describes the aluminum refining process and defines the limits of this analysis, while the mathematical model presents the mathematical equations that implement the information presented in the conceptual model.
The material flow model is based on a literature review of the U.S. secondary aluminum industry. It is intended to provide a defensible basis for developing appropriate exposure scenarios. In addition, the output of the material flow model provides key input to the dose calculations for each scenario. This input consists of radionuclide-specific concentrations in recycle by-products, in effluent, and in waste products of the refining process. Because of the number of scenarios being analyzed and the differing times at which they occur, the mathematical model presented in this section does not include radioactive decay. However, radioactive decay is taken into account in the individual scenarios, in the same manner as in the analyses for steel and copper.
This section presents the conceptual model that describes the movement of aluminum scrap through the normal refining process, beginning with the production of scrap, through refining, manufacturing, product use, and ending with disposal. Figure 6.1 presents a schematic diagram of the overall material flow conceptual model for aluminum. Both the mass and radioactivity air qg-Transportation ' Mamfactunng Aluminum Y
to Refinery dross C Transportation r &
Processing Refinery metalproduct C r
N Transportation Scrap Dealer Recycle Handling Processor
)( Transportation Handling Use A
Existing Recyclers /f. Scrap
- '/ Direct Disposal Disposal r
Figure 6.1 Material flow for aluminum scrap Draft NUREG 1640, Vol. I 6-2
tu
'Section 6 ' Evaluation of Aluminum
- p L follo'w this flow model. There are several distinct steps or processes in the refining process.
iThese are discussed in the following subsections.
l 6.2.1 ' Sources of Material Similar to steel and copper, aluminum recyclers can be the general public (e.g., recycling aluminum cans), industry (e.g., recycling aluminum siding), or manufacturers (e.g., scrap g produced during the manufacture of end products).
There are three types of scrap metal used in the aluminum making industry: home, new, and old.
Home scrap consists of unusable metal produced during the processing or fabrication of aluminum into a form usable for manufacturing. Home scrap is usually high-grade metal with very few impurities. . Even though home scrap is produced at the refinery, it is still considered a secondary metal because it is not the processed raw material. New scrap is produced during manufacture of end products. New scrap also is high-grade metal with very few impurities. Old scrap includes ~ obsolete, wom out or broken products that have been used by the general public or industry. Old scrap.is usually low grade metal and the chemical composition is not well-known. Therefore,it must first be sorted, sized, and classified. Recyclable scrap metal from the nuclear industry is considered old scrap. A total cf 3.19E+06 t (3.5 E+06 tons) of secondary l
aluminum (scrap) was consumed in the U.S. in 1995, and almost half of that was old scrap (USBM 1997).
The main producer of the scrap assumed for this study is the nuclear industry (decommissioned material from nuclear facilities), which consists mainly of commercial power plants, test and aO research reactors, and industrial nuclear facilities. Other producers of such scrap include the Department of Energy (DOE) weapons complex and the Department of Defense (DOD), which would contribute scrap primarily from conventional weapons testing and army and navy test reactors. Approximately 2.5E+02 t/y (2.75 E+02 ton /y) of potentially recyclable aluminum scrap metal is generated each year by licensed facilities. Increased dismantling and decommissioning activities could result in up to 4.50E+03 t/y (5.0E+03 ton /y) of aluminum scrap from these facilities for a limited number of years (NUREG/CR-5610').
Similar to the steel and copper analyses, cleared aluminum scrap is assmned to be mixed with a single source of uncontaminated scrap.
6.2.2 Transportation and Processing Scrap aluminum cleared from a nuclear facility could be transported to a scrap dealer or processor; this would most likely be done by a commercial company. Because not all scrap aluminum would be suitable for recycle, some may be transported directly to a disposal site. In all cases, transportation could occur either by truck or rail.
n ' Recycle / Reuse Literature Search Report, SAIC,1994, scheduled to be published as NUREG/CR 5610.
6-3 Draft NUREG 1640, Vol. I
Ev11uition of Aluminum Section 6 After scrap is processed at a scrap dealer, it is transported by either rail or truck to a refinery.
Dross (refining slag), metal products, and dust also would be transported from the refinery to manufacturers or processors by either truck, rail, or waterway.
6.2.3 Aluminum Mills There are five types of refineries and mills that use aluminum scrap as input: primary scrap processors, secondary smelters, foundries, fabricators, and chemical plants. However, the aluminum scrap produced at nuclear facilities would most likely enter a secondary smelter, i Secondary smelters most commonly use an oil or gas-fired reverberatory furnace. Key modeling parameter values for an aluminum secondary smelter are shown in Table 6.1.
Table 6.1 Key modeling assumptions for aluminum secondary smelter Assumptions Value End product and use sheet, plate, foil, ingot, rod, bar and wire End use of the dust disposed ofin a sanitary landfill r
Temperature inside furnace 650*C Temperature inside the baghouse 190*C Chemical form of elements entering baghouse oxides Efficiency of baghouse 99.9 %
Average size of a charge 50t Average number of charges per year for a single 5580 refinery In 1996, secondary smelters consumed approximately 1.4E+6 t (1.5E+6 tons) of scrap (new +
used). The typical input material for this type of furnace is aluminum scrap and occasionally a small amount of additives (silicon, titanium, and strontium rods). The capacity of a typical reverberatory furnace is approximately 50 t (55 tons). No data were available at the time of this analysis to determine the average number of charges per year for an aluminum refinery; the value used for steel BOF refineries (5580 charges /y) wasjudged to be adequate for aluminum references.
The fumes that are generated during the refining of aluminum scrap are captured by the primary exhaust hood and transported via a duct system to a baghouse. The baghouses used in the refining of aluminum scrap are similar to those used in the iron and steel industry.' Therefore, the same parameters for the baghouse are used for the recycling of aluminum (e.g., temperature, efficiency). Occasionally dirty aluminum scrap undergoes pretreatment to remove iron, oil, and water. Pretreatment consists of crushing and/or drying (using an afterburner). The dust produced during pretreatment is collected in the same baghouse as for the furnace. When the dust is removed from the baghouse, it is tested for hazardous components to determine ifit needs Draft NUREG-1640, Vol. I 6-4 O
Section 6 Evaluation of Aluminum to be handled as hazardous waste. : About 99% of the dust produced during the recycling of p)-
aluminum is not considered hazardous. Therefore, for this analysis the baghouse dust is considered to be nonhazardous.
- During the refining process, the original metal separates into four different end products: off-gas, dust, dross, and metal.(Figure 6.1). Both the' mass and radioactivity partition into the different end products. To account for this in the material flow modeling, partitioning factors for both mass and elements were developed and are discussed in detail in Section 6.3.
Each of the end products undergoes a different process, use, and final disposal process. -The off-gas includes elements that are completely volatilized into stable gases or very fine particles during refining and exit the refinery stack. Dust includes elements that are volatilized from the fumace, form particulates when cooled, and are collected in baghouse filters. (The air pollution control systems are not 100% efficient, and a small percentage of the dust is released into the atmosphere with the off-gas.)
Dross is not considered a hazardous waste, therefore, it can be recycled, reprocessed, or directly disposed of. After dross is removed from the furnace and cooled, it is stored outdoors in piles at the refinery until it is either used by the refinery or transported to a processor. Because ofits high metal content, dross can be fed back into the furnace as input material.
Manufacturing and processing converts dross and metal products created at the refineries and mills into finished products. Manufacturing involves activities such as cutting and shaping the metal. Processing of dross involves crushing and sizing. After a metal product or d.oss is
( manufactured into a finished product, it must be transported and distributed to the general public (i.e., end user). Facilities involved in the distribution of finished metal products include stores, warehouses, and car lots. Ifit is not recycled on-site, dross is usually distributed and transported directly from the refinery where it is produced or from the manufacturer where it is processed.
6.2.4 Product Use Dross or finished metal products are used by the public for many applications. Aluminum metal products are used in containers and packaging, building and construction, transportation, electrical products, consumer durables, and machinery and equipment. Use of dross is similar to that ofiron and steel slag (e.g., roadbed, railroad ballast).
6.2.5 Disposal The ultimate endpoint for finished metal products, dross, and dust is disposal in a public sanitary landfill (i.e., a Resource Conservation and Recovery Act [ RCRA) Subtitle D landfill). The types of objects that could end up in a public sanitary landfill include discarded end products, waste from manufacturing, dross directly from the refinery, products made from dross, scrap not suitable for recycle, and dust.
n 6-5 Draft NUREG-1640, Vol. I t
j Evaluation of Aluminum Section 6 l l
J 6.3 Mass and Elemental Partitioning Factors for Refinery Operations j Partitioning of the radioactivity and mass present in scrap entering the refinery furnace is modeled in order to estimate concentrations of radionuclides in various end products.
Partitioning factors are defined as the estimated fraction of original radionuclide concentration or mass entering the refinery furnace that would be present in various end products. As modeled in this analysis, the mass of scrap metal entering a furnace during the refining process is I redistributed into the three immediate products: metal product, dross, and dust. Partitioning of l radioactivity to these products is also modeled, as well as for the off-gas leaving the refinery stack.
l 6.3.1 Mass Partitioning Factors Mass partitioning factors for aluminum were estimated using information obtained from industry l contacts for the metal product, dross, and dust. According to Alchem Aluminum,' 40% to 90% l of the metal mass entering the fumace ends up in the metal product. If cleaner scrap (new scrap) is used, the percent yield is close to 90%. However, if dross is used with the scrap as input, the 1' percent yield is closer to 40%. The cleared aluminum material being analyzed in this material flow is assumed to be fairly clean and representative of new scrap. Therefore, a range of 40% to 90% is used as the distribution for the mass partitioning for metal product. Because the dust produced during the recycling of aluminum scrap is not considered hazardous, a record of the mass produced per charge is not typically kept by refineries. Between 0.5% and 2% of the original mass entering the furnace is estimated to end up in the dust. The dirtier the scrap input, the more dust is produced. There are very few additives used during the refining of aluminum '
scrap, so the remaining fraction is assumed to be the mass partitioning for dross.
6.3.2 Elemental Partitioning Factors i
In order to simplify the material flow modeling, elements of concern were grouped according to l
their elemental partitioning factors. It was assumed that there were no isotopic effects and that all isotopes of a given element would behave identically.
The primary methods for removing impurities from the melt in the reverberatory fumace are bubbling chlorine through the melt and/or using fluoride fluxes. Whether or not an element remains in the melt depends primarily on its propensity to forin chlorides or fluorides. Calcium is added to the melt to increase the formation ofintermetallic compounds with cadmium, lead, bismuth, and antimony. These compounds float to the top and are incorporated into the dross. In addition to these factors, the chemical and physical properties of the elements in question were also considered, particularly for those elements for which only limited data are available. Where no direct estimates of partitioning were available, elemental partitioning factors were estimated based on the behavior of chemically similar elements.
l
' Personal communication between Mary Anderson of SAIC and Jim Bopp of Alchem Aluminum, May 23,1997. l Draft NUREG-1640, Voi.1 6-6
7-L Section 6 Evaluation of Aluminum The elemental partitioning factor ranges determined for the aluminum material flow model are n]
(
intended to be representative of the expected behavior during melting in a typical domestic
' aluminum reverberatory fumace. Both lack of knowledge about the behavior of elements during 3
the refining of aluminum and variability in refinery conditions contribute to uncertainty in the l l estimates of elemental partitioning factors. In order to address this uncertainty, ranges for the j partitioning values were used, similar to the analyses for steel and copper.
l During refining, elements could partition to one or both of the main melt components (i.e., the dross and/or metal phases) or discharge from the furnace in the volatilized gas. Some of the
' radionuclides that leave the furnace in the volatilized gas would remain in the vapor phase (off- ;
l gas) and some would condense or coalesce into particulates (dust). Elements found in coarse l l particulates would be captured by the baghouse filter. Some of the fine particles and species in !
l the vapor phase would escape in the off-gas exiting the stack.
! ]
- The furnace is assumed to be operating at an average temperature of about 650*C (1200'F). The I average temperature of the baghouse is assumed to be 190 C (375*F). It is assumed that the air flowing through the baghouse is cooled to this temperature. The assumptions listed in Table 6.1 of this report are also used.
l Table 6.2 shows the resulting elemental partitioning factor (EPF) ranges for each element. Note that the partitioning factors for some elements (e.g., iodine) do not sum to 100%. This is due to the use of ranges for partitioning factors. However, this is acceptable because only one material is present in each exposure scenario, and a strict mass balance is not necessary.
6.4 Mathematical Model for Flow of Recycled Aluminum Scrap This section presents the equations that represent the information discussed previously in Section 6.2 and 6.3 and are used to formulate the mathematical model. The equations estimate radionuclide concentrations in refined aluminum and other co-products of refining. The equations are entered into spreadsheets that have been organized and structured specifically for this analysis. The calculated radionuclide concentrations in refined aluminum, dross (refinery s19g), refinery baghouse dust, and the amount of radioactivity released out the refinery stack are used as input to the scenario analyses.
6.4.1. Mixing of Cleared Scrap and Other Scrap There are only two processes by which the original concentration of esch radionuclide in cleared l aluminum scrap can be potentially changed. The first can occur upon mixing with other scrap L metal prior to refining. This mixing is a radionuclide-independent process, so the radioactivity concentration of all radionuclides is effected the same when mixing cleared aluminum scrap with
! a given mass of other aluminum scrap. The second process is the refining process itself, which generally consists of melting the aluminum scrap metal, resulting in a redistribution j (partitioning) of mass and radioactivity. Partitioning of mass during melting is radionuclide-independent, however, partitioning of radioactivity during refining is element-dependent. The 6-7 Draft NUREG-1640, Vol. I
l l
Evaluction of Aluminum Section 6 !
l Table 6.2 Elemental partitioning factor ranges (%) for aluminum refining Metal Baghouse Element Product Dust Dross Off-gas Ac, Th, Pa, U, Np, Pu, Am, Cm, Cr, Fe, Co, Ni, Cu,95-100 0 0-5 0 Mo, Nb, Ag, Cd, Sb, Ir, Pb, Bi, Ra Tc,Ru,Re,Po 70-100 0 0-30 0 C 71-100 0 3.8-6.2 0 Zn 90-99.8 4.8-5.2 0 0 Sr,Ba,Zr 38-62 0 38-62 0 Y, Ce, Pm, Eu 19-31 0 56-94 0 Na, K, Cs, Ca, Mn 0 .95-1.05 94-100 0 P,S,Se 0 0-39 70-100 0 1 0 o 59-100 .6-1.4 Cl 0 29-69 30-70 .9- 1.1 H,Rn 0-5 0 0 95-100 following equations are used to calculate the concentrations in refinery co-products at those points in the material flow which correspond to potential exposure scenarios.
The total mass of material entering the furnace in a year, including cleared and other scrap, was calculated using Equation 6.1.
M i= M + o Af uc 6.1 where Mi = total mass of scrap metal entering the furnace per charge (g/ charge) and Mo = mass of cleared material entering the furnace per charge (g/ charge)
Muc = mass of other scrap metal entering the fumace per charge (g/ charge)
Mixing of cleared scrap with metal from sources other than licensed facility can occur at the scrap dealer (i.e., secondary metal pool) and at the refinery, where material from the primary metal pool enters the fumace. In this analysis, no distinction is made between the two sources of other metal. The mass of other metal includes contributions at the scrap yard and at the refinery.
The radionuclide concentration in the metal entering the furnace was calculated using Equation 6.2. The following equations are intended to be evaluated separately for each radionuclide in the analysis. Therefore, parameters such as concentration, decay factors, decay constants, and dose conversion factors are not explicitly subscripted for each radionuclide.
M C' = = C* 6.2 M,
Draft NUREG-1640, Vol. I 6-8
Section 6 Evaluation of Aluminum p where
> 1 C, =
radionuclide concentration in scrap entering the refining process (pCi/g)
U and
=
Mo mass 6f cleared material entering the furnace per charge (g/ charge)
Mi =
total mass of scrap metal entering the furnace per charge (g/ charge)
=
C. original concentration of cleared material (pCi/g)
For slag, baghouse dust, and off-gas, Equations 6.1 and 6.2 were evaluated using annual average values for the masses of scrap entering the furnaces because all the exposure scenarios for these materials depend on annual average concentrations. For metal, both an annual average and a i single charge evaluation of Equations 6.1 and 6.2 were conducted. This was done for metal I because there are metal products that could easily be manufactured from a single refinery charge.
The single charge concentrations were used in metal product-use exposure scenarios except where noted. (See Appendix D for additional details.)
6.4.2 Refinery Process To accurately account for concentration changes in the different products, the mass of each refinery product must be calculated. Equations 6.3,6.4, and 6.5 are used to calculate the masses of slag, dust, and metal product, respectively.
M, = M, *f,
- CPY 6.3
\
M, = M, *f,,
- CPY 6.4 M ,= M ,*f,, P 6.5 where M, = mass of slag produced from a refinery per year (gly)
M, = mass of dust produced from a refinery per year (g/y)
M, = mass of metal product produced from a refinery per year (g/y) and Mi = total mass of scrap entering the furnace per charge (g/ charge) fo = mass partitioning factor for slag during the refining process (dimensionless) foi
= mass partitioning factor for dust during the refining process (dimensionless) fg = mass partitioning factor for metal product during the refining process (dimensionless)
CPY = number of charges per refinery per year (charge)
The total amount of radioactivity in the original metal entering the furnace during the refining process is partitioned among four product materials. Equation 6.6 shows the calculatiori far
, radionuclide concentration in slag, taking into account both the mass and elemental partitioning (m
V) factors.
6-9 Draft NUREG-1640, Vol. I
Evaluation of Aluminum Section 6 l
C,
- f,
- M, C, f, C='
=
6.6 M, f,, f,,
where C, = radionuclide concentration in slag after the refining process (pCi/g) and Ci = radionuclide concentration in scrap entering the refining process (pCi/g) f, = slag elemental partitioning factor during the refining process (dimensionless)
Mi = total mass of scrap entering the furnace per charge (g/ charge) f,i = mass partitioning factor for slag during the refining process (dimensionless)
The concentration of radionuclides in the dust and metal product are similarly calculated using ;
Equations 6.7 and 6.8, respectively. l C,
- f, C= 6.7 4 di where C. = radionuclide concentration in dust after the refining process (pCi/g) and Ci = radionuclide concentration in scrap entering the refining process (pCi/g) f4 = dust elemental partitioning factor during the refining process (dimension;ess) foi
mass partitioning factor for dust during the refining process (dimensionless) l C
C,*f" 6.8 lpl where !
C, = radionuclide concentration in metal product after the refining process (pCi/g) l and Ci = radionuclide concentration in scrap entering the refining process (pCi/g) f, = metal product elemental partitioning factor during the refining process (dimensionless) f,i = mass partitioning factor for metal product during the refining process (dimensionless)
No mass is explicitly calculated for the off-gas. Exposure scenarios for atmospheric effluents are based on the total amount of radioactivity released from the refinery stack each year. The annual amount of radioactivity in the off-gas was calculated using Equation 6.9.
A, = C, M, . f, = CPY 6.9 i
l Draft NUREG-1640, Voi.1 6-10 O
Section 6 Evaluation of Aluminum l
l w where
- A, =
radioactivity in the off-gases leaving the refinery stack in a year (pCi/y) i and C =
radionuclide concentration in scrap entering the refining process (pCi/g)
M, =
total mass of scrap entering the furnace per charge (g/ charge) f, =
off-gas elemental partitioning factor during the refining process (dimensionless)
CPY = number of charges per refinery per year (charge)
Equations 6.10 and' 6.11 are used to calculate the mass of dust that escapes the baghouse filters and the mass that is captured in the baghouse, respectively.
M,, = M, * ( 1 - BHg) 6.10 l
where ,
M,, =
total mass of dust that escapes the baghouse in a year (g) l M, =
mass of dust produced from the refining process in a year (g) l BH, = baghouse efficiency (dimensionless) l , M,, = M, - M,, 6.1 l where l l M. =
total mass of dust captured in the refinery baghouse in a year (g) l l and M, = l l mass of dust produced from the refining process in a year (g) '
I M,, =
total mass of dust that escapes the baghouse in a year (g) f i
6.5 Radioactivity Concentrations in Aluminum Refining Co-Products l Mean radionuclide concentrations in the co. products of aluminum refming are listed in Table 63. !
These values represent estimated radioactivity concentrations in the refmery output. The values are nomutlized to a unit radioactivity concentration in scrap and are only listed in S.I. units since the values are numerically identical if expressed in conventional units (e.g. pCi/g product per pCi/g scraph l j
As stated above, Table 63 lists the mean concentration of each radionuclide in each medium.
l Tabulations are limited to mean values simply because of the space that would be required if i percentiles from the distributions were also tabulated. The entire distribution ofvalues for each !
radionuclide in the appropriate medium was used as input for the exposure scenario analysis.
i i
{
6 11 Draft NUREG-1640, Vol.1 t
Evaluation of Aluminum Section 6 6.6 Dose Assessment for Unique Aluminum Recycle and Disposal Scenarios Most of the potential exposure scenarios for recycled and disposed aluminum scrap are adequately covered by adapting the steel scrap scenarios described in Section 4. Only one scenario was added to the aluminum analysis that is not already described: a piece of cookware made out of recycled aluminum that is used by a member of the general public in a home situation. This scenario was not included in the set of scenarios for steel because of the small potential doses previously calculated in other analyses (e.g., O'Donnell 1978). However, it was included here because aluminum had not been analyzed in previous studies and because aluminum cookware is commonly used in the U.S. ,
1 Recycled aluminum can be made into a variety of cookware, including large pots, baking pans, l skillets, and coffee pots. The scenario described below involves using an aluminum pot, where i material corroded from the pot might be ingested through the food cooked in it.
6.6.1 Exposure Pathways External: This scenario includes extemal exposure to penetrating radiation from the volume source of an aluminum pot.
Ingestion: If an aluminum pot is used to boil water or cook food, a small amount of material could corrode off the pot and transfer to the water or food in the pot. This material would then be ingested with the prepared food.
Suspension of particulates from aluminum cookware is unlikely, therefore the inhalation pathway is not included.
6.6.2 Mathematical Representation The annual total effective dose equivalent (TEDE) is calculated by adding the effective dose equivalents from the external and ingestion exposure pathways. The TEDE for a member of the public using an aluminum pot is represented by Equation 6.12.
D T"U # iirg O 6.12 where Dr - TEDE for the scenario (mremly) and D,
o
= EDE due to extemal exposure (mrem /y)
D, = EDE due to ingestion (mrem /y)
Draft NUREG-1640, Vol. I 6-12 O
I Section 6 Evaluation of Aluminum i
Table 6.3 Results of material flow model--aluminum refinery l
-g Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
Refined Metal Off-gas Nuclide Single Charge Annual Slag Dust (Bq per Bq/g)
H-3 5.8E-04 9.4E-06 0.0E+00 0.0E+00 9.6E+07 C 14 3.lE-02 4.8E-04 8.4E-05 0.0E+00 0.0E+00 Na-22 0.0E+00 0.0E+00 ' l .6E-03 3.6E-04 0.0E+00 P-32 0.0E+00 0.0E+00 1.4E-03 5.3E-03 0.0E+00 S-35 0.0E+00 0.0E+00 1.4E-03 5.3 E-03 0.0E+00 Cl36 0.0E+00 0.0E+00 8.4 E-04 1.8E-02 9.7E+05 K-40 0.0E+00 0.0E+00 1.6E-03 3.6E-04 0.0E+00 Ca-41 0.0E+00 0.0E+00 1.6E-03 3.6E-04 0.0E+00 Ca-45 0.0E+00 0.0E+00 ' l .6E-03 3.6E-04 0.0E+00 Cr-51 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Mn-54 0.0E+00 0.0E+00 1.6E-03 3.6E-04 0.0E+00 Fe-55 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Co-57 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Co-58 3.5E-02 5.5 E-04 2.8E-05 0.0E+00 0.0E+00 Fe-59 3.5E-02. 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Ni-59 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Co-60 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Ni-63 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Zn-65 3.4E-02 5.3 E-04 0.0E+00 1.8E-03 0.0E+00 f Cu-67 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00
( Se-75 St-85 0.0E+00 1.8E-02 0.0E+00 2.8E-04 1.4E-03 8.4 E-04 5.3 E-03 0.0E+00 0.0E+00 0.0E+00 Sr-89 1.8E-02 2.8E-04 8.4E-04 0.0E+00 0.0E+00 Sr-90 1.8E-02 2.8E-04 8.4E-04 0.0E+00 0.0E+00 Y 91 8.9E-03 1.4E-04 1.3E-03 0.0E+00 0.0E+00 Mo-93 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Nb-93m 3.5E-02 5.5 E-04 2.9E-05 0.0E+00 0.0E+00 Nb-94 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Nb-95 3.5E-02 5.5E 04 2.8E-05 0.0E+00 0.0E+00 Zr-95 1.8E-02 2.8 E-04 8.4E-04 0.0E+00 0.0E+00 Tc-99 3.0E-02 4.8E-04 2.5E-04 0.0E+00 0.0E+00 Ru-103 3.0E-02 4.8 E-04 2.6E-04 0.0E+00 0.0E+00 Ru-106 3.0E-02 4.8E-04 2.5E-04 0.0E+00 0.0E+00 Ag-108m 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Cd 109 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Ag-11Om 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Sb 124 3.5 E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 1125 0.0E+00 0.0E+00 1.3E-03 0.0E+00 9.7E+05 Sb-125 3.5E-02 5.5 E-04 2.8E-05 0.0E+00 0.0E+00 1-129 0.0E+00 0.0E+00 1.3 E-03 0.0E+00 9.8E+05 1 131 0.0E+00 0.0E+00 1.3 E-03 0.0E+00 9.6E+05 Ba-133 1.8E-02 2.8E-04 8.4E-04 0.0E+00 0.0E+00 Cs-134 0.0E+00 0.0E+00 1.6E-03 3.6E-04 0.0E+00 6-13 Draft NUREG-1640, Vol. I
Ev;luation of Aluminum Section 6 Table 6.3 Results of material flow model--aluminum refinery Mean radionuclide concentrations in refinery products (Bq/g product per Bq/g scrap)
Refined Metal Off-gas Nuclide Single Charge Annual Slag Dust (Bq per Bq/g)
Cs-137 0.0E+00 0.0E+00 1.6E-03 3.6E-04 0.0E+00 Cc-141 9.0E-03 1.4E-04 1.3 E-03 0.0E+00 0.0E+00 Ce-144 9.0E-03 1.4 E-04 1.3 E-03 0.0E+00 0.0E+00 Pm-147 8.9E-03 1.4E-04 1.3 E-03 0.0E+00 0.0E+00 Eu-152 8.9E-03 1.4E-04 1.3E-03 0.0E+00 0.0E+00 Eu-154 9.0E-03 1.4 E-04 1.3E-03 0.0E+00 0.0E+00 Eu 155 8.9E-03 1.4E-04 1.3 E-03 0.0E+00 0.0E+00 Re-! 86 3.0E-02 4.8E-04 2.6E-04 0.0E+00 0.0E+00 Ir192 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Pb-210 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Po-210 3.0E-02 4.8E-04 2.5E-04 0.0E+00 0.0E+00 Bi-210 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Rn-222 5.9E-04 9.7E-06 0.0E+00 0.0E+00 9.6E+07 Ra-223 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Ra-224 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Ac-225 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Ra-225 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Ra-226 3.fE-02 5.5 E-04 2.7E-05 0.0E+00 0.0E+00 Ac-227 3.5E-02 5.5E-04 3.0E-05 0.0E+00 0.0E+00 Th-227 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Th-228 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Ra-228 3.5 E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Th-229 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Th-230 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E40 Pa-231 3.5E-02 5.5E-04 3.0E-05 0.0E+00 0.0E+00 Th-231 3.5 E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Th-232 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Pa 233 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 U-233 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Th-234 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 U-234 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 U-235 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Np-237 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Pu-238 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 U-238 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Pu 239 3.5E-02 5.5E-04 2.8E-05 0.0E+00 0.0E+00 Pu-240 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Pu-241 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Am-241 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Cm-242 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Pu-242 3.5E-02 5.5E-04 2.7E-05 0.0E+00 0.0E+00 Cm-244 3.5E-02 5.5E-04 2.9E-05 0.0E+00 0.0E+00 Draft NUREG-1640, Vol. I 6-14 0
f.
I l
Section 6 Evaluation of Alummum )
l-L p).
l t
The mathematical representations f- each exposure pathway are discussed in the following three subsections.
w/
. Equation 6.13 estimates the radicauclide concentration in the aluminum pot at the time use. This l incorporates radioactive decay from the time the scrap aluminum is cleared by a licensed facility.
to the time the scenario begins. The reference to " source material" in the parameters of Equation 6.13 and other equations refers to the material that represents the source of l radioactivity. In this scenario, the source material is an aluminum pot. )
i' t
l i
- Uh 6.13 Co= C, e l where C, =
radionuclide concentration in the source material at time the scenario begins (pCi/g) and C, =
undecayed radionuclide concentration in the source material (pCi/g)
A, = radioactive decay constant (1/d) t, =
time from clearance from nuclear facility to time scenario begins (d)
External Exposure An individual in close proximity to the pot while using it would be exposed to penetrating radiation from the mass of aluminum in the pot. This external exposure is calculated using (A{} Equation 6.14.
D a= Co GF
- UGF *$xs
- ys I O'I A where D., = EDE due to external exposure (mrem /y) and Co
= radionuclide concentration in the source material at time the scenario begins (pCi/g)
GF = geometry factor for the scenario (mrem /h per pCi/g)
Uc, = uncertainty in geometry factor (dimentionless) to -
daily number of hours of exposure for the scenario (h/d) t, = annual number of days of exposure for the scenario (d/y) y Ingestion Exposure While food is being cooked in an aluminum pot, a certain amount of aluminum could corrode off the pot and transfer to the food. The dose due to this exposure pathway is presented in Equation 6.15.
l D,,,=Co *CRg
- DI, Foy
- t,, . DF,,, * (l E -03 ) 6.15 l (
6-15 Draft NUREG-1640, Vol. I l
E '_
Evaluation of Aluminum Section 6 where D., = EDE due to ingestion (mrem /y) and C. =
radionuclide concentration in the source material at time the scenario begins (pCi/g)
CRu = corrosion and transfer rate for aluminum (mg Al/kg food) l DI, = total dietary intake (kg food'd)
= fraction of total dietary intake that is cooked in aluminum pot (dimensionless)
Fm DF., =
ingestion dose factor (mrem /pCi intake) 1 IE-03 = unit conver; ion factor (g/mg) tg = annual nuraber of days of exposure for the scenario (d/y) l l
6.7 Parameter Discussion for All Modeled Scenarios Calculation of potential impacts from recycle of cleared aluminum scrap material depends on many parameter values. Parameter values are needed for both material flow and dose assessment models. The material flow parameter values rely on information from the U.S. secondary aluminum industry. The parameter values for the dose modeling are a function of receptor behavior, such as time on a specific job or breathing rate, as well as how the radionuclides are transported in the environment. The dose modeling parameter values are based on those used in the iron and steel modeling described in Section 4. Only those parameter values that are l different from those used in the iron and steel modeling are discussed in this section, i I
6.7.1 Scenario Timing The same scenario-timing assumptions that are presented for the BOF steel modeling (Section 4) are used for the aluminum modeling.
6.7.2 Dose Evaluation -
This section presents a discussion of parameter values used for the analysis of aluminum recycle scenarios. In general, the same scenarios are analyzed for aluminum recycle as were analyzed for steel recycle in Section 4. Values used for many of the parameters are also the same as for the steel recycle analysis. For some parameters, however, values specific to the recycle of aluminum were used in order to more appropriately model the scenarios as they would likely occur for aluminum recycle. The following discussion is limited to these specific parameter values. If a parameter is not discussed below and listed in Table B.12, the same value as used for the steel evaluation (Table B.7) is used for aluminum.
6.7.2.1 Input Concentrations from the Material Flow ,
The undecayed radionuclide concentration in the source material, C , is used as the source material input concentration for scenario evaluations. This parameter is radionuclide dependent and is calculated in the material flow modeling. Table B.14 lists the sources for C x, as they appear in the mathematical modeling of the material flow (e.g., Cp, concentration in metal product after the ref' ming process).
Draft NUREG-1640, Vol. I 6-16 O
n.
Section'6 Evaluation of Aluminum A. 6.7.2.2 External Exposure Parameters
^ -
This section presents values for those radionuclide-independent parameters used in calculating -
extemal exposure, including those that address duration of exposure and material density.
Values for these parameters are tabulated in Table B.12.
The dose factors for the additional scenario involving use of an aluminum pot are based on the assumption that the use occurs once per day for approximately 30 minutes. A normal residence period of 350 days per year is assumed. From these assumptions, a range of.375 to .5 h/d was used for to.
For the scrap disposal scenario a fixed value of 1.35E+6 g/m2 was used for the density of waste.
6.7.2.3 . ingestion Exposure Parameters -
Radionuclide-independent parameters used in the evaluation ofingestion exposure include those that address environmental and biotic transport, as well as human consumption. This section describes the values for those unique parameters used in the calculation ofingestion exposure.
The only parameters that are different in the aluminum recycling analysis are for the scenario addressing use of aluminum cookware.
When an aluminum pot is used to cook foods, a certain amount of aluminum is corroded and transferred to the food. According to the US Public Health Service, acidic foods, such as
! tomatoes, tomato sauce and applesauce, tend to accumulate more aluminum than other foods (U.S. Public Health Service 1992). Aluminum concentrations in precooked foods (applesauce, green beans, beef, eggs, ham, pudding, rice, and tomato sauce) range from less than 0.10 to 21.6 mg Al/kg food. However, if these foods are cooked in an aluminum pot, the concentrations range from 0.24 to 125 mg Al/kg food (U.S. Public Health Services 1992). This means the increase in aluminum concentration due to cooking in an aluminum pot is from 0.14 to 103.4 mg Al/kg. This range was used for this scenario evaluation, and the average value of 52 mg Al/kg food was used as the most likely value for cry.
A value for dietary intake was calculated using "The Exposure Factors Sourcebook" (AIHC 1995), which presents data for total dietary intake. Data range from 1.4 kg/d for the UK to 1.6 kg/d for the U.S. and are based on food purchased minus a certain percent for waste. Ten percent waste is assumed in the UK while 15% waste is assumed in the U.S. AIHC (1995) suggests a value of 1.6 kg/d be used for purposes of non-U.S. FDA risk assessments. Therefore, a uniform range of 1.3 to 1.6 was used for the total dietary intake, DI . The corrosion and transfer rate discussed above is for a wide variety of foods, so a range of.33 to 1.0 is used for the fraction of total dietary intake that is cooked in the aluminum pot, Fm.
O d 6-17 Draft NUREG-1640, Vol. I
Evaluition of Aluminum Section 6 6.7.2.4 Atmospheric Release Parameters This section presents the values for those radionuclide-independent parameters used for calculating atmospheric dispersion of refmery stack releases from aluminum recycling facilities.
The only radionuclide-independent parameter different from the steel analysis is the total mass of dust that escapes the refimery baghouse in a year, Mm. The distribution calculated in the material flow model is used as the input distribution for this parameter. l l
6.7.3 Aluminum Surface-to-Mass Ratio The surface-to-mass ratios of various aluminum objects (spheres and cylindrical bar stock) were examined in estimating a range for aluminum scrap. Aluminum objects are assumed to have a density of 2.7 g/cm'. Surface-to-mass ratios for various aluminum objects ranges from approximately 0.04 cm 2/g for large-radius spheres and bar stock, up to 10 cm2 /g or higher for very thin sheets and pipes.
Data are not available to provide an adequate basis for choosing a "best estimate" from this range of values. Based on these data and assumptions, the value of surface-to-mass ratio for aluminum is best described by a uniform distribution having a minimum of 1.0 cm2/g and a maximum of 7.0 cm2 /g. The minimum value is characteristic of pipes and sheets having a thickness of 0.25 cm. The maximum value is characteristic of pipes and sheets having a thickness of 0.05 cm.
These surface-to-mass ratios for aluminum are representative of pipes and sheets of various sizes with residual contamination on one side only. A wide variety of aluminum objects commonly found at nuclear facilities have surface-to-mass values that fall within this range.
s 6.8 Dose Factors for Recyc!o and Disposal of Aluminum Scrap i
This analysis of recycle of cleared aluminum scrap includes 17 separate scenarios evaluated for 85 radionuclides. Figure 6.2 shows which scenarios describe the critical groups and for how many radionuclides. There are six scenarios which have the highest mean dose factor for at least one radionuclide. The largest number of radionuclides have critical groups described by scenarios associated with transporting (52 radionuclides) or handling (17 radionuclide) unprocessed scrap. Individuals handling aluminum dross (slag) constitute the critical group for 2 radionuclides. For one volatile radionuclide (H-3), the critical group consists ofindividuals exposed to atmospheric releases from the refining process. Thirteen radionuclides are limited by ,
scenarios associated with use of consumer products made from recycled aluminum. Use of aluminum cookware accounts for 11 of these radionuclides and use of a small metal object close to the body accounts for two of them. Table 6.4 lists the mass-based dose factors for each radionuclide. Table 6.5 lists the corresponding derived surficial dose factors for each radionuclide. Results for all 17 aluminum scenarios are tabulated in Appendix H.
The mcan values of the critical-group dose factors for each radionuclide are listed in Table 6.4 as the " critical-group dose factor." These represent the dose to the average member of the critical group exposed to radioactivity distributed throughout the mass of cleared aluminum (Bq/g or Draft NUREG-1640, Vol. I 6-18 O
1 l
l Section 6 Evaluation of Aluminum p pCi/g). The circumstances of that exposure are described by the scenario indicated in the right
( hand column. The 5*,50*, and 95'h percentiles listed for each radionuclide represent the underlying distribution of dose factors calculated for each critical group. The range of values from the 5* to the 95th percentile is the 90% confidence interval on the dose factor. That is, there is a 90% certainty that the dose factor for the average member of the critical group lies within this interval. The confidence interval is a subjective measure of uncertainty in the dose factor i that includes estimates of the variability and uncertainty in the parameters used in each scenario.
The ratio of the 95* to the 5* percentile is a useful measure of the relative width of the 90%
confidence interval for comparison between scenarios. Smaller values of the 95/5 ratio indicate less uncertainty than larger values. The scenarios with the smallest uncertainty are those with the fewest number of exposure pathways and the least uncertainty in the parameters describing those pathways. The scrap transportation scenario accounts for 52 of the 85 radionuclides. It has the smallest uncertainty of all the critical group scenarios with a 95/5 ratio of about 2 for most -
radionuclides. The sources of uncertainty in this sce'nario are similar to those for the steel scrap transportation scenario discussed in Section 4.9.
For all scenarios that take place subsequent to the initial transport of scrap, additional sources of uncertainty are introduced and wider confidence intervals result. Scenarios that address handling {
of scrap include uncertainty due to dilution with other scrap. They also include additional exposure pathways-inhalation of resuspended dust and inadvertent ingestion under dusty conditions. Scenarios that address handling of refinery products such as aluminum dross include additional uncertainty in how much of each radionuclide is partitioned to these materials. In 1 addition, the aluminum cookware scenario includes uncertainty in dietary practices. For I aluminum, this group of handling, processing, and consumer product scenarios have 95/5 ratios that range from about 10 to about 20.
Greater uncertainty is associated with scenarios that involve multiple exposure pathways and complex submodels. One radionuclide (H-3) has a critical group consisting ofindividuals living in the vicinity of an aluminum refinery and exposed to atmospheric releases. This scenario includes an atmospheric dispersion model and pathways for ingestion, inhalation, and extemal exposure, each of which contributes to uncertainty in the dose factor. In this case, the atmospheric release scenario has a 95/5 ratio of 50. Most of this uncertainty is due to the atmospheric dispersion model with additional contributions from uncertainties in the ingestion dose pathway.
The mean values of the derived surficial dose factors for each radionuclide in Table 6.5 represent the dose to the average member of the critical group exposed to radioactivity initially distributed over the surface cleared aluminum scrap (Bq/cm 2 or pCi/cm2 ). Derived surficial dose factors are calculated from mass-based dose factors by use of a surface-to-mass ratio, appropriate for typical aluminum objects available for clearance. The surface-to-mass ratio is used to derive surficial dose factors as described in Section 4.7.
l 6-19 Draft NUREG 1640, Vol. I l
I Evaluation of Aluminum Section 6 O
I 60 - ~
Alumin ~ um Critical Group Scenarios 50 m g.
h?b l
- L4.3 4
,, l
@ 40. - M yp .. - ._. - ... .-
G g M
.9 o
Nc
- 4%
g 30 _ pp . _ _ _ _ . . _ _ _ . _ _
w o
in
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i
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! 20-- - hf
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k .
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Figure 6.2 Scenarios describing critical groups for aluminum recycle O
Draft NUREG-1640, Vol.1 6-20 1
Section 6 Evaluation of Aluminum O Table 6.4 Aluminum recyc'le critical-group dose factors-mass
( (pSv/y per Bq/g) (mrentl y per pCi/g)
U 90% Confidence interval 90% Confidence interval
, g ,
group 5* 50* 95* group $* 50* 95*
dose (lower (median) (upper dose (lower (rnedian) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario H3 1.8E-06 1.3E-07 9.4E-07 6.6E-06 6.6E-09 4.9E-10 3.5E-09 2.5E-08AL-ATMO-REFINER-N C 14 2.6E-04 5.2E-05 2.lE-04 5.8E-04 9.4E-07 1.9E-07 7.9E-07 2.2E-06AL-METL-COOKWAR-N Na 22 4.4E+00 2.8E+00 4.4E+00 6.0E+00 1.6E-02 1.0E-02 1.6E-02 2.2E-02AL-SCRP-TRANSPO-W P-32 2.6E-03 1.7E-03 2.6E
. ,r.wr
~N,, i d1Mb@.,-03 .213.6E-03 9.7E-06 6.2E-06 9.6E-06 SGP-Nj]1.3E-05AL-SCR
.,,-m
-.3m-.,,,-,.., -
.a .
W Cl 36 6.8E-04 4.4E-04 6.8E-04 9.4E-04 2.5E-06 1.6E-06 2.5E-06 3.5E-06AL-SCRP-TRANSPO-W K-40 3.2E-01 2. l E-01 3.3E-01 4.5 E-01 1.2E-03 7.7E-04 1.2E-03 1.6E-03 AL SCRP-TRANSPO-W Ca-41 1.0E-05 1.2E-06 6.9E-06 2.9E-05 3.8E-08 4.4E-09 2.6E-08 1.lE-07AL-DROS-HANDLIN-W Ca-45 3.0E-05 1.9E-05 3.0E-05 4.2E-05 1.lE 07 7.lE C[glig,d3 4 fE42jl. f!E.p2 4.9,Mj6.8E-0,23 - . _ ,-08 1.lE .07 1.5E-07AL.SCRP
.,---,-----..-,y,~ . . , - . - . . ~ - . - . ~ . _ - . ,
3 1 Mn-54 1.7E+00 1.!E+001.7E+00 2.3E+00 6.3E-03 4.0E-03 6.3E-03 8.7E-03 AL-SCRP TRANSPO-W Fe-55 7.3E-05 1.6E-05 6.3E-05 1.6E-04 2.7E-07 5.9E-08 2.3E-07 6.lE-07AL-METL-COOKWAR-N Co-57 7.6E-02 4.9E-02 7.6E-02 1.0E-01 2.8E-04 1.8E-04 2.8E-04 3.9E-04 AL-SCRP-TRANSPO-W Co-58 1.9E+00 1.2E+001.9E+00 2.6E+00 7.0EC 4.5E-03 7.0E-03 9.7E-03 AL-SCRP-TRANSPO-W bb - h.
Ni-59 2.9E-05 6.2E-06 2.4E-05 6.7E-05 1.lE-07 2.3E-08 9.0E-08 2.5E-07AL METL-COOKWAR-N Co-60 5.lE+00 3.3E+00 5.lE+00 7.0E+00 1.9E-02 1.2E-02 1.9E-02 2.6E-02AL-SCRP-TRANSPO-W Ni-63 8.2E-05 1.8E-05 7.0E-05 1.9E-04 3.0E-07 6.7E-08 2.6E-07 6.9E-07AL-METL-COOKWAR-N Zn 65 1.2E+00 7.6E-01 1.2E+001.6E+00 4.4E N,Sk
~ .7c;-
Nd..I.Ey232;1,Mj3.8E42>7.2E-02h,
. y.-- -.-.,~.y. . . .
-03 2.8E-03 4.4E-03 6.lE-03 AL
.5E4417.9EQl.4E-047.1h,,.SCRE-TRfNSPO-Wjpj
.s Se-75 4.9E-01 3. l E-01 4.9E-01 6.8E-01 1.8E-03 1.2E-03 1.8E-03 2.5E-03 AL-SCRP-TRANSPO-W Sr-85 9.4 E-01 6.0E-01 9.4E-01 1.3E+00 3.5E-03 2.2E-03 3.5E-03 4.8E-03 AL-SCRP-TRANSPO-W Sr-89 2.3E-03 1.5E-03 2.3E-03 3.2E-03 8.6E-06 5.5E-06 8.6E-06 1.2E-05 AL-SCRP-TRANSPO-W Sr-90 1.0E-02 1.9E-03 8.8E-03 2.4E w._-02 3.8E-05 7.lE-06 3.3E-05 8.9E-05 AL-METL-COOKWAR-N
.m.,,,.4h,mM M-,.m.-,.s.,j m., ,. .mw,--w , , ,.r. --
1*9S$$w~9.
. 5d Egg 4,1E@3{6.9M%6E43].--,, 46E!0,5,J L6E;05j.2,,.6E-05g3}E-0,,,5 SP,0-Wg Mo-93 5.5E-04 8.4E-05 4.lE-04 1.6E-03 2.lE-06 3.lE-07 1.5E-06 5.8E-06AL-METL-SMOBJCT-N Nb-93m 8.7E-05 1.5E-05 6.5E-05 2.4E-04 3.2E-07 5.4E-08 2.4E-07 8.8E-07AL-METL-SMOBJCT-N Nb-94 3.3E+00 2.1E+00 3.3E+00 4.5E+00 1.2E-02 7.8E-03 1.2E-02 1.7E-02 AL-SCRP-TRANSPO-W Nb-95 1.4E+00 9.3E-01 1.4E+00 2.0E+00 5.4E-03 3.4E-03 5.3E-03 7.4E-03 AL-SCRP-TRANSPO-W
$ EDEkEMl,3,747E433MW@@lMM Tc-99 1.8E-04 4 lE-05 1.4E-04 4.5E-04 6.7E-07 1.5E-07 5.2E-07 1.7E-06 AL-METL-COOKWAR-N Ru 103 9.3E-01 5.9E-01 9.2E-01 1.3E+00 3.4E-03 2.2E-03 3.4E-03 4.7E-03AL-SCRP-TRANSPO-W Ru-106 4.lE-01 2.6E-01 4.lE-01 5.7E-01 1.5E-03 9.8E-04 1.5E-03 2.lE-03 AL-SCRP-TRANSPO-W Ag-108m 3.2E+00 2.1E+00 3.2E+00 4.5E+00 1.2E-02 7.7E-03 1.2E-02 1.6E-02 AL-SCRP-TRANSPO-W . n .- ,
\ - .g w n en ,- -w i i C. d409,4y.~r.,,rr-.1.,3.E43$2.8E'04<11E.43.
.d -~ -
!1. 8E.-03Jt. 7E- 06il. .- 0. ... .
0 . - -ME E 06l.4.'0E46..M
.T.~L-CO. 0E..y v,m.e O.K. W...AR.-R.
6-21 Draft NUREG-1640, Vol. I
Evaluation of Aluminum Section 6 Table 6.4 Aluminum recycle critwabgroup dose factors-mass (pSv/y per Bq/g) (mrem /y per pCi/g) 90% Confidence interval 90% Confidence interval p g group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag-110m 5.7E+00 3.6E+00 5.7E+00 7.8E+00 2.1E-02 1.3E-02 2.lE-02 2.9E-02AL-SCRP-TRANSPO-W Sb-124 3.6E+00 2.3E+00 3.6E+00 5.0E+00 1.3E-02 8.5E-03 1.3E-02 1.9E-02AL-SCRP-TRANSPO-W I-125 1.3E-03 8.3E-04 1.3E-03 L8E-03 4.8E-06 3.lE-06 4.8E-06 6.7E-06AL-SCRP-TRANSPO-W Sb-125 8.lE-01 5.2E-01 8.lE-01 1.lE+00 3.0E-03 1.9E-03 3.0E-03 4.lE-03 AL-SCRP-TRANSPO-W
- b.$k 3 k. b k $h_ b N 1-131 5.0E-01 3.2E-01 4.9E-01 7.2E-01 1.9E-03 1.2E-03 1.8E-03 2.7E-03 AL-SCRP-TRANSPO-W Ba-133 5.6E-01 3.6E-01 5.6E-01 7.7E-01 2.lE-03 1.3E-03 2.lE-03 2.8E-03AL-SCRP-TRANSPO-W Cs-134 3.2E+00 2.1E+00 3.2E+00 4.4E+00 1.2E-02 7.6E-03 1.2E-02 1.6E-02 AL-SCRP-TRANSPO-W Cs-137 1.2E+00 7.9E
.- - w-n-.
m-9d%,2~r--> 15aEgM. 5m,g
~-
-01 w 1.2E+001.7E+00 p-
,-m , % .-- ,.
4.6E-03 2.9E-03
.c- ,- w .~.
4.6E-03 6.3E 03 A Cc-144 6.6E-02 4.2E-02 6.6E-02 9.lE-02 2.4E-04 1.6E-04 2.4E-04 3.4E-04 AL SCRP-TRANSPO-W Pm-147 5.5E-05 1.2E-05 4.5E-05 1.2E-04 2.0E-07 4.6E-08 1.7E-07 4.6E-07AL-SCRP-HANDLIN.W Eu-152 2.2E+00 1.4E+00 2.2E+00 3.lE+00 8.2E-03 5.3E-03 8.2E-03 1.lE-02 AL-SCRP TRANSPO-W Eu-154 2.4E+00 1.6E+00 2.48+00 3.3E+00 9.0E-03 5.8E-03 9.0E-03 1.2E-02 AL-SCRP-TRANSFO-W
~ m y y - w - , ~ n . ,,.n.
~ w , y . ~ ,.. ~ . ...n y n -.w -.,,n n - n.m.
Eu-155W2.1E-02 W1.4E42?2.1E-02h2.9E-02L7.9E-05:5.0E4,557.9E-05 al!! ,,L-SCRP-TRAN,S_PO ,WJ Re 186 4.9E-03 2.9E-03 4.7E-03 8.0E-03 1.8E 05 1.lE-05 1.7E-05 2.9E-05 AL-SCRP-TRANSPO-W 1r-192 1.4E+00 9.lE-01 1.4E+00 2.0E+00 5.2E-03 3.3E-03 5.2E-03 7.2E-03 AL-SCRP-TRANSPO-W Pb-210 7.5E-01 1.7E-01 5.9E-01 1.8E+00 2.8E-03 6.3E-04 2.2E-03 6.8E-03 AL-METL-COOKWAR-N Po-210 7.4E-02 1.6E-02 6.2E-02 1.6E-01 2.7E-04 5.8E-05 2.3E-04 6.0E-04 AL-METL-COOKWAR-N ,,
w , _.,- y m . , n- v. , _m Bif 210Q6]EM3.8F@4]6.0E-0439.5E-04h2'3E-0,6]1.4_EQQE_-06j, fd,,SCkPyIRANS.POlWff Rn-222 1.7E+00 1.0E+001.6E+00 2.8E+00 6.3E-03 3.7E-03 6.0E-03 1.0E-02AL-SCRP-TRANSPO-W Ra-223 3.6E-01 2.3E-01 3.6E-01 5.l E-01 1.3E-0.' 3.5E ')4 1.3E-03 1.9E-03 AL-SCRP-TRANSPO-W Ra-224 1.2E+00 7.2E-01 1.2E+00 2.0E+00 4.5E-03 2.6E-03 4.3E-03 7.3E-03 AL-SCRP-TRANSPO-W Ac-?25 2.8 E-01 1.8E-01 2.8E-01 4.0E-01 1.0E-03 6.7E-04 1.0E-03 1.5E-03 AL-SCRP-TRANSPO-W ---,,s~~
pm -e.
. vngww 3g2'4E 03;r 6 0372.0E-02fn:n .nm.m. ~~h--v-Ra-225_g,p 9.6E-0 L8.'0 3.5E 05J3-06,g.0Mg& ,SQRP 2 H ANQL11J-WQ Ra-226 3.5E+00 2.2E+00 3.5E+00 4.8E+00 1.3E-02 8.3E-03 1.3E-02 1.8E-02 AL-SCRP-TRANSPO-W Ac-227 1.9E+00 4.4E-01 1.7E+00 4.2E+00 7.lE-03 1.6E-03 6.2E-03 1.6E-02AL METL-COOKWAR-N Th-227 1.2E-01 7.6E-02 1.2E-01 1.6E-01 4.3E-04 2.8E-04 4.3E-04 6.0E-04 AL-SCRP-TRANSPO-W Th-228 2.5E+00 1.6E+00 2.5E+00 3.5E+00 9.4E-03 6.0E-03 9.4E-03 1.3E-02 AL-SCRP-TRANSPO-W-
$$$$ 55 . 5 .5k $$YY 5" Th-229 2.3E+00 4.2E-01 1.9E+00 5.2E+00 8.4E-03 1.6E-03 6 9E-03 1.9E-02 AL-SCRP-HANDLIN-W Th-230 3.4 E-01 6.3E-02 2.8E-01 7.9E-01 1.3E-03 2.3E-04 1.0E-03 2.9E-03 AL-SCRP-HANDLIN-W Pa-231 1.5E+00 3.0E-01 1.3E+00 3.7E+00 5.5E-03 1.lE-03 4.8E-03 1.4E.02 AL-METL-COOKWAR-N Th-231 '.3.0E-04 6.6E-05 2.2E-04 7.7E-04 1.lE 06 2.5E-07 8.0E-07 2.8E-06AL-SCR"-TRANSPO-W n,mg m _ .-,.n. n . ~ --- v n. -_ v - n-n. n n- ..n
'1b-232 gM,l'.5E+00]2.8E-Ol[e,n.,-,.~,- _-1.2E+00 3.5E+00_ f.6E-03)).0E-0314.6E-03,f13
~
3 Draft NUREG-1640, Vol.1 6-22 l
Section 6 Evaluation of Aluminum
("3 Table 6.4 Aluminum recycle critical-group dose factor $-mass i, ) (pSv/y per Bq/g) (mrtm/y per pCi/g) 90% Confidence interval 90% Confidence interval Cribl- 3, group 5* 50* 95* group 5* $0* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Pa-233 2.6E-01 1.7E-01 2.6E-01 3.6E-01 9.8E-04 6.3E-04 9.7E-04 1.3E-03 AL-SCRP-TRANSPO-W U 233 1.8E-01 3.2E-02 1.4E-01 4. l E-01 6.5E-04 1.2E-04 5.4E-04 1.5E-03 AL-SCRP-HANDLIN-W Th-234 1.5E-02 9.5E-03 1.5E-02 2.0E-02 5.4E-05 3.5E-05 5.4E-05 7.4E-05 AL-SCRP-TRANSPO-W U-234 1.7E-01 3.lE-02 1.4E-01 4.0E-01 6.4E-04 1.2E-04 5.2E-04 1.5E-03 AL-SCRP-HANDLIN-W Np-237 3 h .Nb b I . b 7.2E-01 1.5E-01 5.9E-01 1.7E+00 2.7E-03 5.5E-04 2.2E-03 6.lE-03 AL-SCRP-HANDLIN-W Pu-238 3.8E-01 6.8E-02 3.lE-01 8.7E-01 1.4E-03 2.5E-04 1.lE-03 3.?E-03 AL-SCRP-HANDLIN-W U-238 1.5E-01 2.8E-02 1.3E-01 3.6E-01 5.7E-04 1.0E-04 4.7E-04 1.3E-03 AL-SCRP-HANDLIN-W Pu-239 4.0E-01 7.3E ^2 3.3E
. n . - .- -- -~ nn n. 1.5E-03 2.7E-04 1.2E-03 3.4E-03 AL-SCRP._HANDLIN W. -
1M2@.bg,4pE-pjlgy,@m.,_-01 9.3E-01333E-0119.3E,-01[p5E-039 7E-04}l.2,E-
. , , - - .,.n..-~n,~.n..,.--.- . n. , n..
Pu-241 6.5E-03 1.2E-03 5.3E-03 1.5E-O' '. 4E-05 4.3E-06 2.0E-05 5.5E-05 AL-SCRP-HANDLIN-W Am-241 5.9E-01 1.2E-01 4.9E-01 1.4E+t/' 2.2E-03 4.4E-04 1.8E-03 5.0E-03 AL-SCRP-HANDLIN-W Cm 242 2.3 E-02 4.5E-03 1.9E-02 5.2E-02 8.4E-05 1.7E-05 6.8E-05 1.9E-04 AL-SCRP-HANDLIN W Pu-242 3.8E-01 7.0E-02 3.lE-01 8.8E-01 1.4E-03 2.6E-04 1.2E-03 3.3E-03 AL-SCRP-HANDLIN-W
,O Cm-244 3.3 E-01 6.7E-02 2.7E-01 7.6E-01 1.2E-01 2.5E-04 1.0E-03 2.8E-03 AL-SCRP-HANDLIN W A )-
(J 6-23 Draft NUREG-1640, Vol. I
. . ._ _9
Evaluation of Aluminum Section 6 Table 6.5 Aluminum recycle critical-group dose factors-surficial (pSv/y per Bq/cm ) 2 (mremly per pCi/cm )
Critical- 90% Confidence interval Critical- 90% Confidence interval group 5* 50* 95 group 5* 50" 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario H-3 6.8E-06 5.lE-07 3 lE-06 2.3E-05 2.5E-08 1.9E-09 1.2E-08 8.5E-08 AL-ATMO-REFINER-N C-14 1.0E-03 1.5E-04 7.5E-04 2.7E-03 3.8E-06 5.5E-07 2.8E-06 1.0E-05 AL-METL-COOKWAR-N Na-22 1.8E+01 4.7E+00 1.6E+01 3.4E+01 6.6E-02 1.7E-02 6.lE-02 1.2E-01 AL-SCRP-TRANSPO-W P-32 1.lE-02 2.9E-03 9.6E-03 2.0E-02 3.9E-05 1.lE-05 3.6E-05 7.6E-05 AL-SCRP-TRANSPO-W 5 3 I Cl-36 2.8E-03 7.3E-04 2.5E-03 5.2E-03 1.0E-05 2.7E-06 9.4E-06 1.9E-05 AL-SCRP-TRANSPO-W K-40 1.3E+00 3.5E-01 1.2E+00 2.5E+00 4.9E-03 1.3E-03 4.5E-03 9.2E-03 AL-SCRP-TRANSPO-W Ca-41 4.lE-05 3.4E-06 2.5E-05 1.3E-04 1.5E-07 1.3E-08 9.2E-08 4.8E-07AL-DROS-HANDLIN W Ca-45 1.2E-04 3.2E 05 1.lE-04 2.3E-04 4.5E 07 1.2E
- n. .o - , .n Cr-51@cM2.0B-0195.3P)02Pl.8E-01!3.8E-01f.: . , , ;, .-07 4.2E-07 8.6E-07AL-S
. ,_ ~.; - ~, ,..,n. ~. , + . , .
. .~~ ~ .~ 7'4E4402.0E-0446.7E-04 l1:4E-03lAL%CRP-TRANSPO-WO.
Mn-54 6.9E+00 1.8E+00 6.3E+001.3E+01 2.5E-02 6.7E-03 2.3E-02 4.8E-02 AL-SCRP-TRANSPO-W Fe-55 2.9E-04 4.4E-05 2.2E-04 7.9E-04 1.lE-06 1.6E-07 8.lE-07 2.9E-06AL-METL-COOKWAR-N Co-37 3. l E-01 8.lE-02 2.8E-01 5.8E-01 1.lE-03 3.0E-04 1.lE-03 2.2E-03 AL-SCRP-TRANSPO-W Co-58 7.7E+00 2.0E+00 7.0E+001.5E+01 2.8E 02 7.5E ,._-03 m .y-2.6E-... ~.,02 5.4E-02
-,.y.s AL ,SCRP-TRANSPO-W,3Et%?_5EW1,8 5EfM L8
..,,s_ , , . , , - . . - . . - . _ - - , .
fer59,jy},Q,.,,.. -[_,,, ,.
Ni-59 1.2E-04 1.8E-05 9.0E-05 3.lE-04 4.3E-07 6.6E-08 3.3E-07 1.lE-06 AL-METL-COOKWAR-N l l
Co-60 2. l E+01 5.4E+00 1.9E+01 3.9E+01 7.6E-02 2.0E-02 7.0E-02 1.4E-01 AL-SCRP-TRANSPO-W '
Ni-63 3.2E-04 5.3E-05 2.5E-04 8.lE-04 1.2E-06 2.0E-07 9.2E-07 3.0E-06 AL-METL-COOKWAR-N 1 Zn-65 4.8E+00 1.3E+00 4.5E+00 9.lE+00 1.8E-02 4.7E-03 1.6E-02 3.4E-02 AL I
-m.m., -n ~ ,.m g
_. - .~].n.v Cg61gM1,qE-0114,2E42,tifEyl$3JE-0,1 ji2E-04ilJE-04dE-0Qi4E-0_3 n.m,m.n-,-<.~, - h, _.-.v.n. ,-SCRP-TRANSPO-W RETRANSPCW. . n~,,,j.
1 l
Se-75 2.0E+00 5.2E-01 1.8E+00 3.8E+00 7.3E-03 1.9E-03 6.7E-03 1.4E-02 AL-SCRP-TRANSPO-W Sr 85 3.8E+00 1.0E+00 3.5E+00 7.2E+00 1.4E-02 3.7E-03 1.3E-02 2.7E-02 AL-SCRP-TRANSPO-W f 1
Sr-89 9.4E-03 2.5E-03 8.6E-03 1.8E-02 3.5E-05 9.2E-06 3.2E-05 6.6E-05 AL-SCRP TRANSPO-W Sr.90 4.0E-02 5.7E-03 2.8E-02 1.2E-01 1.5E-04 2.lE-05 1.0E-04 4.3E-04 AL METL-COOKWAR-N
. . - - y, _.--.-y-,,.,m~. .m ey.p., w.m..m.,-- p y . -n Mig;,,M2.8B-02h7f4E_-03 2.6E-02ES.3Egjjt0E-04%2.7E-05'.925E-05V2.0E_-04jAl 1 SCRPMRANSPO-Wij Mo-93 2.2E-03 2.4E-04 1.4E-03 6.4E-03 8.lE-06 8.8E-07 5.2E-06 2.4E-05AL-METL-SMOBJCT-N Nb-93m 3.4 E-04 3.7E-05 2.3E-04 1.lE-03 1.3E-06 1.4E-07 8.4E-07 4.0E 06AL-METL-SMOBJCT-N Nb-94 1.3E+01 3.5E+001.2E+012.5E+01 4.9E-02 1.3E-02 4.5E-02 9.3E-02 AL-SCRP-TRANSPO-W Nb-95 5.8E+00 1.6E+00 5.3E+001.lE+01 2.2E-02 5.8E-03 2.0E-02 4.1E-02 AL-SCRP-TRANSPO-W 9b. NN -. 2$5,,7,E43pE4224.(@NU5k Tc-99 7.2E-04 1.2E-04 5.0E-04 1.9E-03 2.7E-06 4.3E-07 1.8E-06 7.l E-06 AL-METL-COOKWAR-N Ru 103 3.7E+00 1.0E+00 3.4E+00 7.lE+00 1.4E-02 3.7E-03 1.3E-02 2.6E-02AL-SCRP-TRANSPO-W Ru-106 1.7E+00 4.4E-01 1.5E+00 3.2E+00 6.2E-03 1.6E-03 5.7E-03 1.2E-02 AL-SCRP-TRANSPO-W Ag-108m 1.3E+01 3.4E+00 1.2E+01 2.5E+01 4.8E-02 1.3E-02 4.5E-02 9.2E-02 AL-SCRP-TRANSPO-W Draft NUREG-1640, Vol. I 6-24
1 I
Section 6 Evaluation of Aluminum Table 6.5 Aluminum recycle critical-group dose factors--surficial (G)v (pSv/y per Bq/cm2 ) (mrem /y per pCi/cm )
Critical. 90% Confidence interval Critical. 90% Confidence interval group 5* 50* 95* group 5* 50* 95*
dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario M M5[t @ j@.?@ meg 2MI),Epp,WjfMjM h _QM Ag-110m 2.3E+01 6.0E+00 2.lE+014.3E+01 8.5E-02 2.2E-02 7.8E-02 1.6E-Ol AL-SCRP-TRANSPO-W Sb-124 1.5E+01 3.9E+001.3E+012.8E+01 5.4E-02 1.4E-02 5.0E-0? 1.0E-01 AL-SCRP-TRANSPO-W I-125 5.3 E-03 1.4E-03 4.8E-03 1.0E-02 1.9E-05 5.lE-06 1.8E-05 3.7E-05 AL-SCRP-TRANSPO-W Sb-125 3.3E+00 8.7E-Ol 3.0E+00 6.2E+00 1.2E-02 3.2E-03 1.lE-02 2.3E-02AL-SCRP-TRANSPO-W
$ [ 3 % M W 8 " b N 5 k h h [2 [ h ( $ d t'E M M I-131 2.0E+00 5.6E-01 1.9E+00 4.0E+00 7.5E-03 2.lE-03 5.9E-03 1.5E-02AL-SCRP-TRANSPO-W Ba-133 2.3E+00 5.9E-01 2.lE+00 4.3E+00 8.3E-03 2.2E-03 1.7E-03 1.6E-02AL-SCRP-TRANSPO-W Cs-134 1.3E+01 3.4E+001.2E+012.4E+01 4.8E-02 1.3E-02 4.4E-02 9.lE-02AL-SCRP-TRANSPO-W Cs-137 5.0E+00 1.3E+00 4.5E+00 9.5E+00 1.8E.02 4.9E
~ , w s.- - . m . - ,, ,,, w. -~ ,. 03 mum 1.7E-02
- n. , . , -3.5E-02
. - AL-SCRP,TRANSPO-W
-M.n$.mr,,w n., - m.x
.!fg2 2Edl,d.9Eg.0E.0lg4.1E41[,8]1EM 2.2E-04)7.4E-0411!SE-03h- ay, SCR P-TRANSPO-WO Ce-144 2.7E-01 7.0E-02 2.5E-01 5.0E-01 9.8E-04 2.6E-04 9.lE-04 1.9E-03 AL-SCRP-TRANSPO-W Pm-147 2.2E-04 3.6E-05 1.7E-04 5.9E-04 8.2E-07 1.3E-07 6.2E-07 2.2E-06AL-SCRP-HANDLIN W Eu-152 9.0E+00 2.4E+00 8.3E+00 1.7E+01 3.3E-02 8.8E-03 3.lE-02 6.3E-02 AL-SCRP-TRANSPO-W i Eu-154 9.8E+00 2.6E+00 9.lE+00 1.9E+01 3.6E-02 9.6E-03 3.4E-02 6.9E-02AL-SCRP-TRANSPO-W
} v Eu;155yd8.6E42;,pE-02;7.9E-02JJ.6E-01U.2_E-04,g.4,Ep512.9,E 0416.0E-041A_ L-SC, y
p-~S,,PAWJ
.-~~n RPM-~m mr.nn.nn~. -.- v nw -~ ~~~w~
Re-186 2.0E-02 5.5E-03 1.8E-02 4.2E-02 7.4E-05 2.lE-05 6.7E-05 1.6E-04 AL-SCRP-TRANSPO-W Ir192 5.7E+00 1.5E+00 5.2E+00 1.lE+01 2.lE-02 5.6E-03 1.9E-02 4.0E-02 AL-SCRP-TRANSPO-W Pb-210 3.0E+00 4.5E-01 2.2E+00 8.lE+00 1.lE-02 1.7E-03 8.3E-03 3.0E-02 AL-METL-COOKWAR-N Po-210 2.9E-01 4.3E-02 2.2E-01 7.8E-01 1.!E-03 1.6E-04 8.lE-04 2.9L'-03 AL-METL-COOKWAR-N h E k .h NB 5 b Rn-222 6.9E+00 1.9E+00 6.3E+001.5E+01 2.6E-02 7.lE-03 2.3E-02 5.4E-02AL SCRP-TRANSPO-W Ra-223 1.5E+00 4.lE-01 1.3E+00 2.9E+00 5.4E-03 1.5E-03 4.9E-03 1.lE-02AL-SCRP-TRANSPO-W Ra-224 4.9E+00 1.4E+00 4.5E+00 1.lE+01 1.8E-02 5.lE-03 1.7E-02 3.9E-02AL-SCRP-TRANSPO.W Ac-225 1.lE+00 3.2E-01 1.0E+00 2.3E+00 4.2E-03 1.2E-03 3.9E-03 8.3E-03 AL-SCRP-TRANSPO-W WWYS:Y -
Ybl Y5$$ $ :-
Ra-226 1.4E+01 3.7E+00 1.3 E+01 2.7E+01 5.2E-02 1.4E-02 4.8E-02 9.8E-02 AL SCRP-TRANSPO-W Ac-227 7.6E+00 9.8E-01 5.8E+001.9E+01 2.8E-02 3.6E-03 2.2E-02 7.2E-02 AL-METL-COOKWAR-N n-227 4.7E 01 1.3E-01 4.3E-01 9.lE-01 1.8E-03 4.8E-04 1.6E-03 3.4E-03 AL-SCRP-TRANSPO-W Th-228 1.0E+01 2.7E+00 9.5E+001.9E+01 3.8E-02 1.0E-02 3.5E-02 7.2E-02AL-SCRP TRANSPO W bb b h_-. ,_-E[+0ih, h,,[k[d[ M d[
Th-229 9.2E+00 1.3E+00 6.7E40 2.5E+01 3.4E-02 4.6E-03 2.5E-02 9.3E-02AL SCRP-HANDLIN-W n-230 1.4E40 1.9E-01 1.0E+00 3.8E+00 5.lE-03 7.0E-04 3.8E-03 1.4E-02 AL-SCRP-HANDLIN-W p Pa-231 5.9E40 9.lE-01 4.3E+00 1.5E+01 2.2E-02 3.4E-03 1.6E-02 5.5E-02 AL-METL-COOKWAR-N 6-25 Draft NUREG-1640, Vol.1 l
l
Evaluation of Aluminum Section 6 Table 6.5 Aluminum recycle critical-group dose factors-surficial (pSv/y per Bq/cm ) (mrem /y per pCi/cm )
Critical. 90% Confidence interval Critical. 90% Confidence interval group 5* 50* 95 group 5* 50* 95*
dose (lower (median) (upper dc.;e (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario l Th-231 1.2E-03 1.8E-04 7.4E-04 4.0E-03 4.5E-06 6.6E-07 2.8E-06 1.5E-05AL-SCRP-TRANSPO-W Pa-233 k 5 bb bfbb h b 1.lE+00 2.8E-01 9.8E-01 2.0E+00 3.9E-03 1.lE-03 3.6E-03 7.5E-03 AL-SCRP-TRANSPO-W U 233 7.2E-01 9.5E-02 5.2E-01 2.0E+00 2.6E-03 3.5E-04 1.9E-03 7.3E-03 AL-SCRP-HANDLIN W 1
Th-234 5.9E-02 1.6E-02 5.4E-02 1.lE-01 2.2E-04 5.8E-05 2.0E-04 4.lE-04 AL-SCRP-TRANSPO-W '
U-234 7.0E-01 9.3E-02 5.lE-01 1.9E+00 2.6E-03 3.4E-04 1.9E-03 7.lE-03 AL-SCRP-HANDLIN.W Np-237 N$ Y S .W.&b $ .b. W$
2.9E+00 4.2E-01 2.2E+00 8.0E+00 1.lE-02 1.6E-03 8.0E-03 2.9E 02 AL-SCRP-HANDLIN-W Pu-238 1.5E+00 2.0E-01 1.lE+00 4.2E+00 5.6E-03 7.5E-04 4.lE-03 1.5E-02 AL-SCRP-HANDLIN-W U-238 6.3 E-01 8.3E-02 4.6E-01 1.7E+00 2.3C-03 llE-04 1.7E-03 6.4E-03 AL-SCRP-HANDLIN-W Pu-239 1.6E+00 2.2E-01 1.2E+00 4.5E+00 6.0E-03 8.0E-04 4.4E-03 1.7E-02 AL-SCRP-HANDLIN-W h2h k h EE N d hhh3[hh h Nk M M [
Pu-241 2.6E-02 3.5E-03 1.9E-02 7.2E-02 9.7E-05 1.3E-05 7.0E-05 2.7E-04 AL-SCRP-HANDLIN.W Am-241 2.4E+00 3.4E-01 1.8E+00 6.5E+00 8.9E-03 !.3E-03 6.6E-03 2.4E-02AL-SCRP-HANDLIN-W Cm-242 9.lE-02 1.3E-02 6.7E-02 2.5E-01 3.4E-04 4.7E-05 2.5E-04 9.3E-04 AL-SCRP-HANDLIN-W Pu-242 1.5E+00 2.lE-01 1.lE+00 4.2E+00 5.7E-03 7.6E-04 4.2E-03 1.6E-02 AL-SCRP-HANDLIN-W j Cm-244 1.3 E+00 1.9E-01 9.9E-01 3.6E+00 4.9E-03 7.0E-04 3.7E-03 1.4E-02 AL-SCRP-HANDLIN.W i
The calculation of derived surficial dose factors is probabilistic. The parameter SM is represented by a distribution of values that incorporate the variability and uncertainty in the surface-to-mass ratio of typical aluminum objects available for clearance. This additional source i of uncertainty results in wider confidence intervals for the surficial dose factors than for the j mass-based dose factors from which they are derived. The relative importance of this additional i uncertainty depends on the scenario. For scenarios with the narrowest confidence intervals, the added uncertainty can contribute as much as an additional 50% to the width of the confidence !
interval. The mass-based dose factor for the scrap transportation scenario has a 95/5 ratio of about 2 for most radionuclides. The corresponding derived surficial dose factors have a 95/5 ratio of about 3. The added uncertainty in surface-to-mass ratio has a relatively smaller impact on the confidence interval for scenarios with larger uncertainties, contributing an additional 10%
to 30%.
Draft NUREG-1640, Vol. I 6-26 O
7 EVALUATION OF RECYCLE AND DISPOSAL OF CONCRETE o
[G' Seven potential exposure scenarios for cleared concrete debi'is that are realistically based on current American industries are evaluatedin this section. As in the evaluations for metals, concrete scenario categories include handling andprocessing. transportation, product use, and disposal. Unique to the concrete evaluation is the inclusion of a scenario invoMng a resident on the site of a closedlandfill. A radionuclide-specific, probabilistic dose factor distribution was calculated for the members of all exposed groups. Dose factors foran average member of each criticalgroup was calculatedin the same manner as for metals recycle. The mean dose factor for each cntical group is reported in normalized units of pSv& per Bq/g scrap (mremfy per pCilg) and pSv/y per Bq/cm' (mrem & per pCi/cm') for each radionuclide. Dose factors at the 5*, 50", and 95* percentiles are also reported.
Similar to the metals analyses, the most common critical group consists of commercial truck drivers canying cleared concrete debris, accot.nting for critical group designation for almost half (33) of the 85 radionuclides in the analysis. Unlike the metals analyses, the scenario involving a resident on a closed landfill containing cleared concrete debris was ana!yzed and included in critical group determination.
This scenario accounts for critical group designation for one-third (28) of the radionuclides in the analysis. Scenarios involving handling concrete debris accounted for most of the remaining critical groups.
Mean critical-group dose factors range from a high of 7E+04 pSv4 per Bq/g (3E+02 mrem & per pCi/g) for Np-237 to a low of 3E-03 pSv/y per Bq/g (1.3E-05 mrem & perpCi/g) for Fe-55. The surficial mean critical-group dose factors range from 1.4E+03 pSvh per Bq/cm' (Np 237) down to SE-05 pSv4 per Bqhm" (S-35). The Np-237 highest mean dose factors are a factor of 30 higher than the next highest mean dose factor. The high mean dose factor of Np-237 is the highest calculated for all materials (metals and concrete) and is attributed to the drinking-water exposure pathway in a residential scenario
& on the site of a closedlandfill. Seventy-four of the radionuclide-specific, mean dose factors for concrete cntical groups are 270 pSv4 per Bq/g orlower (1 mrem /y per pCi/g).
This section describes the technical e luation of the recycle and disposal of concrete debris that could be cleared by Nuclear Regulatory Commission (NRC) licensed facilities. Similar to the analyses of metal scrap (Sections 4,5, and 6), the likely flow of cleared concrete was probabilistically modeled, distributions of radionuclide concentrations in recycled products and disposed materials were calculated, and potential doses to average members of potential critical groups were estimated.
7.1 Introduction to Analysis The analysis process for calculating potential exposures from concrete recycle and disposal is relatively simple when compared to the analyses conducted for recycled and disposed metals. A simple material flow model specific to concrete recycle and disposal was developed, radioactivity concentrations in reprocessed concrete were calculated, and scenario evaluations were conducted. In contrast to the metal analyses, the processing of concrete does not involve redistribution of radionuclides, and there is only one resulting end product. The exposure scenario evaluations for concrete are similar to those for the metals, with only several minor scenario parameter differences, and only one fundamentally different scenario is used in the A determination of critical groups (resident on a closed landfill site).
7-1 Draft NUREG-1640, Vol. l
I Evaluation of Concrete Section 7 7.2 Flow of Recycled and Disposed Concrete The material flow model for concrete represents the general processes that concrete cleared by l NRC licensed facilities would go through from the time of clearance to the time of final disposal. l Decontamination is assumed to have already taken place and is not included in the model. The material flow model comprises two types of models: conceptual and mathematical. The conceptual model describes the recycling process and defines the limits of this analysis, while the mathematical model presents the mathematical equations that implement the information presented in the conceptual model.
The material flow model is based largely on information gathered from personal communications with individuals in the concrete recycling industry. It is intended to provide a defensible basis for developing appropriate exposure scenarios for recycled concrete. In addition, the output of the material flow model provides key input to the dose calculations for each scenario. This input consists of radionuclide-specific concentrations in recycle products containing recycled concrete, in effluents, and in waste products of the recycling process. Because of the number of scenarios being analyzed and the differing times at which they occur, the mathematical model presented in this section does not include radioactive decay. Like other materials, this is accounted for in the s scenario evaluations.
This section presents the conceptual model that follows the concrete through a typical recycling process, beginning with cleared concrete debris, through the recycling process, product use, and l ending with disposal. Figure 7.1 presents a schematic diagram of the conceptual mo:lel of the overall flow of recycled and disposed concrete. The modeling of both mass and radioactivity in recycled concrete follow this flow model. As seen in Figure 7.1, there are several distinct steps in the recycling process. Each of these are discussed separately in the following subsections.
> Transportation > Manufacturing Recycle p ,,,, 4 _
1f A Transportation Handling Use A
Existing ! f V
/ Direct Disposal Disposal 1
l Figure 7.1 Conceptual model of the overall flow of recycled and disposed concrete Draft NUREG-1640, Vol. I 7-2 O
Section 7 Evaluation of Concrete 7.2.1 Source of Material
' O:
.P Concrete for recycling comes mainly from commercial sources, which contributes concrete from demolished buildings or parking lots.
The main producer of concrete debris (scrap) for this analysis is the nuclear industry, which consists mainly of commercial power plants, test and research reactors, and industrial nuclear facilities. Other producers of concrete debris include the Departraent of Energy (DOE) weapons complex and the Department of Defense (DOD), which could contribute concrete debris primarily from conventional weapons testing and army and navy test reactors.
Unlike the metals analyzed, concrete is more likely to be recycled only during the decontamination and decommissioning (D&D) of a nuclear facility. This would result in a large amount of concrete available for recycling during a very short period of time. The D&D of a typical pressurized water reactor would result in about 180,000 t (198,000 tons), whereas approximately 348,000 t (383,000 tons) would be available from a typical boiling water reactor (NUREG/CR-5610'). Large masses of concrete could also be available during the D&D of non-reactor facilities.
7.2.2 Transportation and Processing Concrete debris cleared from a nuclear facility may be transported, usually by a commercial company, to the processor. Processing could also occur at the origination site of the concrete debris. The operations at both places are similar. Because not all concrete debris is likely to be suitable for recycle, some would be transported directly to a disposal site. In both cases, transportation would occur by truck. This transportation could occur either before or after processing occurs.
Prior to use, concrete debris must be crushed and sorted. Any steel rebar in the concrete would be removed with a magnet prior to crushing and sent to an iron and steel refinery. The concrete must be in blocks approximately 1.5 x 1.5 x 0.8 m to be crushed. During crushing, water is sprayed on the dust to contain it. Although not required by regulation, workers near the site typically wear dust respirators. One major recycler ofconcrete, Dykes Paving & Construction Co., Inc., recycles about 230,000 t (250,000 tons) of concrete per year.2 As soon as the concrete debris is needed after. processing and crushing, it is transported by truck to the site of the final use.
' Recycle / Reuse Literature Search Report, SAIC,1994, scheduled to be published as NUREG/CR 5610.
2 Persona: communication between M. Anderson. SAIC, and J. Dykes. Dykes Paving and Construction Co., Inc.,
January 13,1997.
l 7-3 Draft NUREG-1640, Vol. I
)
l Evalunion of Concrete Section 7 )
7.2.3 Manufacturing In order to prepare recycled, crushed concrete debris for final use, it is mixed with a small amount of additives. The additives are added to promote adhesion. According to Dykes, it is very common for the final concrete end product to be made of entirely recycled concrete and additives, although occasionally other aggregate is added to the recycled concrete. If the recycled concrete is used just as aggregate, such as for the base of roadways, then there is no additional processing after the crushing and sizing at the scrap dealer / processor.
7.2.4 Product Use Typical end products for recycled concrete include the base for roads, a stabilizer for asphalt, and an aggregate for non-structural materials. Recycled concrete is not used as aggregate in j structural concrete, such as that used in houses or buildings.' '
7.2.5 Disposal The ultimate endpoint for some concrete is a public sanitary landfill (i.e., Resource Conservation and Recovery Act (RCRA) Subtitle D landfill). Concrete debris that is not suitable for recycling i is sent directly to a landfill. Also, end products containing recycled concrete can also be sent to a landfill after use.
i 7.3 Mathematical Model for the Flow of Recycled Concrete Debris This section presents the equations that represent the information discussed previously in Section 7.2 and are used to formulate the mathematical model According to the material flow conceptual model, there is only one point at which the cleared concrete debris radionuclide concentration is potentially changed: mixing with other concrete or aggregate before or during recycling. Dilution with other concrete is radionuclide independent.
The following equations calculate the concentrations at points ofinterest (i.e., where scenarios would occur).
The total mass of material entering the recycling facility in a year, including cleared concrete debris and other concrete / aggregate was calculated using Equation 7.1.
M 7 =M+M c cs 71 where
=
Mr total mass of material entering the recycling facility in a year (g/y)
' Personal ammunication between M. Anderson, SAIC, and J. Dy kes, Dykes Paving and Construction Co., Inc.. j January 13.1997. !
Draft NUREG-1640, Vol. I 7-4
Section 7 Foaluation of Concrete l
I f-~N and
'(A Me =
=
mass of cleared concrete debris entering the recycling facility per year (g/y)
Mc4 mr.ss of other concrete debris! aggregate entering the recycling facility per year (g/y)
The radionuclide concentration in the recycled concrete entering the manufacturing process was calculated using Equation 7.2. The following equations are intended to be evaluated separately
! for each radionuclide in the analysis. Therefore, parameters such as radionuclide concentration, decay factors, decay constants, and dose conversion factors are not explicitly subscripted for each radionuclide.
MC C. = .C C 7.2 M7 where N C7 =
radionuclide concentration in recycled concrete entering the manufacturing process (PCi/g) and
=
Mc mass of cleared concrete debris entering the recycling facility per year (g/y)
=
Mr total mass of material entering the recycling facility in a year (g/y)
=
Ce original radionuclide concentration of cleared concrete debris (pCi/g) 7.4 Radioactivity Concentrations in Concrete Recycle Products Radioactivity concentrations in concrete recycle products are calculated using the models described in the previous sections. The evaluation for concrete recycle and disposal assumes some mixing of cleared concrete debris with other concrete debris. No mass or elemental partitioning occurs during processing. Therefore, for a unit radionuclide concentration in cleared concrete, the concentration in concrete recycle products would be the same for all radionuclides and all scenarios except immediate handling or transport of cleared concrete.
The radioactivity concentrations that characterize the distribution calculated in the concrete material flow model are listed in Table 7.1.
Table 7.1 Results of concrete material flow model Radionuclide concentrations.in recycled concrete (Bq/g per Bq/g concrete debris)
Scenario Category Mean 5* 50^ 95*
Large Object' 8.7E-01 7.82E-01 8.83E-01 9.40E-01 Other Scenarios 9.71E-01 8.61 E-01 9.93 E-01 1.00E+00 l
- a. The only concrete scenario using this set of radionuclide concentrations is CN-SCRP-LGMASS-N.
t A
7-5 Draft NUREG-1640, Vol. I
I l Evaluttion of Concrete Section 7 7.5 Dose Assessment for Concrete Recycle and Disposal There are no scenarios in addition to those discussed for steel that are used for the evaluation of concrete recycling and disposal. However, because landfill disposal oflarge masses of concrete is more likely than for metals, a landfill resident scenario was included in the determination of critical groups for concrete. For other scenarios, the analyses are the same as described for steel l recycle in Section 4, except for several parameter value differences. These are discussed in the i next section.
7.6 Parameter Discussion Calculation of potential impacts from recycle of cleared concrete depends on many parameter values. Parameter values are needed for both material flow and dose assessment models. The material flow parameter values rely on information from the concrete recycling industry. The parameter values for the dose modeling are a function of receptor behavior, such as time on a specific job or breathing rate, as well as how the radionuclides are transported in the environment. The dose modeling parameter values used for evaluation of concrete recycling and disposal are generally the same as those used in the iron and steel modeling. Only those parameter values that are different than those used in the iron and steel modeling are discussed in this section.
7.6.1 Scenario Timing As described previously, all exposure scenarios were derived from the material flow conceptual modeling, and scenarios were assumed to occur at specific points in time following clearance from the NRC licensed facility. In order to incorporate radioactive decay between clearance and scenario dose modeling, the specific times were quantified as described in this section. Where a reference was used as a basis for the assumed time period, it is cited. If no citation is given, general knowledge of practices gained from talking with industry personnel combined with professional judgement was used as the basis. The following is a list of basic assumptions that were used in developing the timing of the concrete recycle scenarios:
Scrap Handling:
All scrap concrete is assumed to be initially taken to a scrap processor. It takes approximately 4 days for the scrap concrete to reach the scrap dealer.
Reficing and Processing:
- The scrap concrete remains at the scrap processor for a period of approximately 7 days prior to use or disposal.
1 O
Draft NUREG-1640, Vol.1 7-6
L' Section 7 Evaluation of Concrete Use and Disposal:
j ' t*J A recycled concrete product is used for 30 years, based on an assumed use in the L construction industry.
Post-Disposal:
A sanitary landfill operates for 40 years.
Disposed items are placed in the landfill at the midpoint of the landfill operating period.
Post-closure monitoring oflandfills is done for 30 years.
A disposal site is released for potential residential use after post-closure monitoring ends.
Specific scenario timing values are listed in Appendix B, Table B.15.
7.6.2 Dose Evaluation This section presents a discussion of parameter values used for the analysis of concrete recycle scenarios.' The analysis of seven concrete scenarios is based on the scenario descriptions l provided in the steel analysis (section 4). Similar scenarios are analyzed using the same models as for the steel recycle analysis. Values used for many of the parameters are also the same as for the steel recycle analysis. For some parameters, however, values specific to the recycle of concrete were used in order to more appropriately model the scenarios as they would likely occur for concrete recycle. The following discussion is limited to these specific parameter values. If a
'O parameter is not discussed below and listed in Table B.15, the same value as used for the steel j evaluation (Table B.7) is used for concrete. j 7.6.2.1 input Concentrations from the Material Flow The undecayed radionuclide concentration in the source material, C x, is used as the source material input concentration for scenario evaluations. For concrete recycling, this parameter is radionuclide-independent and is calculated in the material flow modeling. Representative values from the input concentration are listed in Table 7.1.
7.6.2.2 External Exposure Parameters l The only unique parameter value used for evaluation of the external pathway for concrete recycle is the density of concrete, for which a fixed value of 2.33E+6 g/m 2was used.
7.6.3 Concrete Surface-to-Mass Ratio The surface-to-mass ratio for concrete is representative of concrete slabs (e.g., floors and walls) ;
i with residual radioactivity on only one side. The surface-to-mass ratio is not sensitive to the size 1 I
l of the pieces made from these slabs but is sensitive to the original thickness of the slabs. The surface-to-mass ratio is also dependent on the density of concrete.
r d 7-7 Draft NUREG-l'640, Vol.1
Evtluation of Concrete Section 7 The typical thickness of wall and floor slabs is assumed to range from 15 to 46 cm (6 to 18 in). !
Concrete for normal construction purposes ranges in density from 1.6 to 3.2 g/cm3 (100 to 200 lb/ft))(Chen,1995). Data are not available to provide an adequate basis for choosing a "best estimate" for either thickness or density of concrete slabs at NRC licensees. Based on these data and assumptions, the value of the parameter SM for concrete is best described by a uniform distribution with a minimum of 0.007 cm 2/g and a maximum of 0.04 cm2 /g. The minimum value corresponds to a thick slab of high-density, e.g., a 46 cm (18 in) slab with a density of 3.2 g/cm3 (200 lb/ft)). The maximum value corresponds to a thin slab oflow density, e.g., a 15 cm (6 in) slab with a density of 3.2 g/cm3 (100 lb/ft)).
7.7 Dose Factors for Concrete Recycle and Disposal 1 1
This analysis of recycle of cleared concrete scrap includes 7 separate scenarios evaluated for 85 radionuclides. Figure 7.2 shows which scenarios describe the critical groups and for how many radionuclides. There are four scenarios which have the highest dose factor for at least one radionuclide. The largest number of radionuclides have critical groups described by scenarios associated with transporting (33 radionuclides) or handling (14 radionuclides) unprocessed I debris. Individuals engaged in roadbed construction activities using cleared concrete scrap j constitute the critical group for 10 radionuclides. For 28 radionuclides, the critical group l consists ofindividuals reriding on closed landfills containing buried concrete scrap. Table 7.2 lists the limiting mass-based dose factors for each radionuclide. Table 7.3 lists the corresponding derived surficial dose factors for each radionuclide. Results for all 7 concrete scenarios are tabulated in Appendix I.
l The mean values of the critical-group dose factors for each radionuclide are listed in Table 7.2 as i the " critical-group dose factor." These represent the dose to the average member of the critical group exposed to radioactivity distributed throughout the mass of cleared concrete (Bq/g or i pCi/g). The circumstances of that exposure are described by the scenario indicated in the right hand column. The 5*,50*, and 95* percentiles listed for each radionuclide represent the underlying distribution of dose factors calculated for each critical group. The range of values i from the 5* to the 95* percentile is the 90% confidence interval on the dose factor. That is, there is a 90% certainty that the dose factor for the average member of the critical group lies within this interval. The confidence interval is a subjective measure of uncertainty in the dose factor that includes estimates of the variability and uncertainty in the parameters used in each scenario.
l l l l l
! l l
Draft NUREG-1640, Vol.1 7-8 O
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Section 7 Evaluation of Concrete
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7-9 Draft NUREG-1640, Vol. I o
p Eva!uation of Concrete Section 7 Table 7.2 Concrete recycle critical-group dose factors-.--mass (pSv/y per Bq/g) (mrem /y per pCi/g) g 90% Confidence interval 90% Confidence interval gg, group 5* 50* 95* group 5* 50* 95* dose (lowcr (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario H-3 8.8E-03 9.9E-06 5.0E-04 3.9E-02 3.3E-05 3.7E-08 1.9E-06 1.5E-04CN-SCRP-LANDFIL-N C-14 1.6E+01 2.7E-02 1.lE+00 5.7E+0! 5.9E-02 1.0E-04 4.lE-03 2.lE-01 CN-SCRP-LANDFIL-N Na-22 2.2E+02 1.4E+02 2.2E+02 3.0E+02 8.1E-01 5.3E-01 8.1E-01 1.1E+00CN-SCRP-TRANSPO-W P-32 1.4E-01 8.6E-02 1.4E-01 1.9E-01 5.lE-04 3.2E-04 5.0E-04 7.2E-04CN SCRP-TRANSPO-W w..y . . ,. -r -. ~ . m . m n w -, 6*3$M$$$,MigEyD_}gM6}ghyE35MJ,E36fl.2E-05423E4M3--,-HANDLIN-W4 Cl-36 1.6E+021.0Et001.9E+015.4E+02 5.9E-01 3.9E-03 6.9E-02 2.0E+00CN-SCRP-LANDFIL-N K-40 4.7E+01 1.9E-01 5.7E+00 2.2E+02 1.7E-01 6.9E-04 2.lE-02 8.2E-01CN-SCRP-LANDFIL-N Ca-41 4.8E+00 1.4E-02 4.6E-01 1.9E+01 1.8E-02 5.2E-05 1.7E-03 7.0E-02CN-SCRP-LANDFIL-N Ca-45 1.8E-02 6.4E-03 1.7E-02 3.4E-02 6.7E-05 2.4E-05 6.2E-05 1.3E-04CN-SCRP-HANDLIN W
$ 155 $ . .YYk9 k5 h h Mn-54 8.5E+01 5.6E+01 8.4E+01 1.2E+02 3.2E-01 2.l E-01 3.lE-01 4.4E-01 CN-SCRP-TRANSPO-W Fe-55 3.4E 03 1.lE-03 3.2E-03 6.5E-03 1.3E-05 4.2E-06 1.2E-05 2.4E-05CN-SCim HANDLIN-W Co-57 6.6E+00 1.4E+00 5.9E+00 1.3E+0! 2.4E-02 5.3E-03 2.2E-02 5.0E-02CN-SCRP-ROADBED W Co-58 9.6E+01 6.2E+01 9.5E+01 1.3E+02 3.5E-01 2.3E-01 3.5E-01 4.9E-01 CN-SCRP-TRANSPO-W
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Nb-93m 2.0E-02 7.8E-03 1.8E-02 4.2E-02 7.5E-05 2.9E-05 6.7E-05 1.6E-04CN-SCRP-HANDLIN-W l Nb-94 2.9E+02 4.4E-01 2.lE+01 1.lE+03 1.lE+00 1.6E-03 7.9E 02 3.9E+00CN SCRP-LANDFIL-N Nb-95 7.4E+01 4.7E+01 7.3E+01 1.0'I+02 2.7E-01 1.7E-01 2.7E-01 3.8E-01CN SCRP-TRANSPO-W M @ h E, W 7E k f M [0IIU 32.EEdS[1[h[2M.t}3341Di?$]C$hSd[ , Tc-99 1.2E+02 8.8E-01 1.8E+014.6E+02 4.4E-01 3.3E-03 6.7E-02 1.7E+00CN-SCRP-LANDFIL-N Ru-103 4.7E+01 3.0E+01 4.7E+01 6.6E+01 1.7E-01 1.lE-01 1.7E-01 2.4E-01CN SCRP-TRANSPO-W l Ru-106 2. l E+01 1.3E+01 2.0E+01 2.9E+01 7.6E-02 5.0E.02 7.6E-02 1.lE 01CN SCRP-TRANSPO-W l Ag-108m 1.7E+02 2.3E-01 1.2E+017.4E+02 6.4E-01 8.6E-04 4.4E-02 2.7E+00CN SCRP-LANDFIL-N l bh2 h 9 h Nb k ! Draft NUREG-1640, Vol. I 7-10
r Section 7 Evaluation of Concrete l p Table 7.2 Concrete recycle critical-group dose factors-mass
- i (pSv/y per Bq/g) (mrem /y per pCi/g)
(d . 90% Confidence interval g; 90% Confidence interval C h l-group 5* 50* 95* group 5* 50* 95* l dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag l10m 2.8E+02 1.8E+02 2.8E+02 3.9E+02 1.0E+00 6.8E-01 1.0E+00 1.4E+00CN SCRP-TRANSPO-W Sb 124 1.8E+02 1.2EM)2 1.8E+02 2.5E+02 6.8E-01 4.3E-01 6.7E-01 9.3E-01 CN-SCRP-TRANSPO-W I125 3.0E-01 1.lE-01 2.9E-01 5.8E-01 1.lE-03 4.lE-04 1.lE-03 2.2E-03CN-SCRP-ROADBED W l Sb-125 4. l E+01 2.6E+01 4.0E+01 5.6E+0! 1.5E-01 9.8E-02 1.5E-01 2.lE-01 CN-SCRP-TRANSPO-W I kW5j*f5Q h.hf$6hlhh&$@M I 131 2.8E+01 1.6E+0! 2.7E+014.0E+01 1.0E-01 5.9E-02 1.0E-01 1.5E-01 CN-SCRP-TRANSPO-W Ba 133 2.8E+01 1.8E+01 2.8E+01 3.9E+0 ! 1.0E-01 6.7E-02 1.0E-01 1.4E-01 CN-SCRP-TRANSPO-W Cs-134 1.6E+02 1.0E+02 1.6E+02 2.2E+02 5.9E-01 3.9E-01 5.9E-01 8.2E-01 CN-SCRP-TRANSPO W Cs-137 6.2E+01 4.0E+01 6.,,.l mE+01
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R 232stf43 W @v0031@. ehgt0h. .M+00.{,6.9Fe0353.9E 01d, 7E+0th- vINDFIL m.N,Q (v) , I 7-11 Draft NUREG-1640, Vol. I
1 Evaluation of Concrete Section 7 Table 7.2 Concrete recycle critical-group dose factors-mass (pSv/y per Bq/g) (mrem /y per pCi/g) g;g 90% Confidence interval ' " *"**"*"" Critical-group 5* 50* 95* group 5* 50* 95* dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Pa-233 1.4E+01 8.6 E+00 1.3 E+01 1.9E+01 5.0E-02 3.2E 02 5.0E-02 7.0E-02CN-SCRP-TRANSPO-W U-233 1.7E+02 6.8E-01 1.7E+016.0E+02 6.lE-01 2.5E-03 6.3E-02 2.2E+00CN-SCRP-LANDFIL-N Th 234 7.5E-01 4.7E-01 7.4E-01 1.0E+00 2.8E-03 1.7E-03 2.7E-03 3.9E-03CN-SCRP-TRANSPO-W U 234 1.7E+02 4.0E-01 1.6E+016.5E+02 6.2E-01 1.5E 03 6.lE-02 2.4E+00CN-SCRP-LANDFIL-N Np-237
$$ b5 7.lE+04 9.0E+0! 4.0E+03 2.2E+05 2.6E+02 3.3E-Oi 1.5E+01 8.0E+02CN-SCRP-LANDFIL-N Pu-238 1.7E+02 5.4E+0! 1.5E+02 3.8E+02 6.4E-01 2.0E-01 5.6E-01 1.4E+00CN SCRP-HANDLIN W U 238 1.3E+02 4.0E-01 1.5E+015.7E+02 4.8E-01 1.5E-03 5.5E-02 2.lE+00CN-SCRP-LANDFIL-N Pu-239 2.2E+02 2.8E-01 1.6E+017.lE+02 8.3E-01 , 1.0E-03 5.8E-02 2.6E+00CN-SCRP
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l Section 7 Evaluation of Concrete l Table 7.3 Concrete recycle critical-group dose factors-surficial l 1 (pSv/y per Bq/cm )2 (mrem /y per pCi/cm ) l g 3
\.j l gg, 90% Confidence interval 90% Confidence interval gg, group 5* 50* 95* group $$ 50* 95*
dose (lower (tnedian) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario H-3 1.9E-04 1.9E-07 1.1E-05 7.9E-04 7.1E-07 7.1E-10 4.0E-08 2.9E-06CN SCRP-LANDFIL-N C 14 3.7E-01 6.4E-04 2.4E-02 1.2E+00 1.4E-03 2.4E-06 8.9E-05 4.6E-03 CN-SCRP-LANDFIL N Na-22 3.2E+00 1.3E+00 5.0E+00 1.0E+01 1.9E-02 6.7E-03 1.8E-02 3.7E-02CN SCRP-TRANSPO W P-32 5.2E-03 1.lE-03 3.lE-03 6.lE-03 1.2E-05 4.lE-06 1.lE-05 2.3E-05 CN-SCRP-TRANSPO-W l Cl-36 3.2E+00 1.8E-02 3.9E-01 1.2E+01 1.2E-02 6.7E-05 1.5E-03 4.4E-02 CN-SCRP-LANDFIL-N l l K-40 1.lE+00 4.0E-03 1.3E-01 5.5E+00 4.0E-03 1.5E-05 4.7E-04 2.0E 02 CN-SCRP-L.ANDFIL-N Ca-41 1.2E-01 3.2E-04 9.7E-03 4.7E 01 4.3E-04 1.2E-06 3.6E-05 1.7E-03 CN-SCRP-LANDFIL-N Ca-45 4.2E-04 9.5E-05 3.6E-04 1.0E-03 1.6E 06 3.5E-07 1.3E-06 3.7E-06CN-SCRP-HANDLIN-W b b .gi5,7[0]2,,h )M)[,h[Q3,hM[hESPOE- j ) Mn-54 2.0E+00 7.0E-01 1.9E+00 3.9E+00 7.4E 03 2.6E-03 7.lE-03 1.4E-02 CN-SCRP-TRANSPO-W Fe 55 8.0E-05 1.7E-05 6.7E-05 1.9E-04 3.0E 07 6.3E-08 2.5E-07 7.lE-07CN-SCRP-HANDLIN-W Co-57 1.5E-01 2.6E-02 1.2E-01 3.9E-01 5.7E-04 9.5E-05 4.5E-04 1.4E 03 CN-SCRP-ROADBED-W Co-58 2.3E+00 7.9E-01 2.lE+00 4.4E+00 8.4E-03 2.9E-03 7.9E-03 1.6E-02 CN-SCRP-TRANSPO-W
. e n.m.n. . m._,.n n. g.-n.
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~
b 1[6P M 'IU 2[156E E INEI45671'FA5klh, 3@,h[h3 Se 75 5.9E-01 9.8E-02 4.6E-01 1.5E+00 2.2E-03 3.6E-04 1.7E-03 5.5E-03 CN-SCRP-ROADBED-W Sr-85 1.lE+00 3.9E-01 1.lE+00 2.2E+00 4.lE-03 1.4E-03 3.9E-03 8.0E-03CN SCRP-TRANSPO-W Sr-89 3.3E 03 8.4E-04 2.7E-03 7.6E-03 1.2E-05 3.lE 06 9.9E-06 2.8E-05 CN SCRP ROADBED-W St-90 5.5E-02 5.5E-05 2.6E-03 1.6E-01 2.0E-04 2.0E-07 9.7E 06 6.0E 04CN-SCRP-LANDFIL-N ar m
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X $ w. M M 0E-021 y2.lEgg,7 8Ey124.F.32 ig).:7 8E,,-06h. . . E4J5._2E
.... M_ .mSCRP-R,OADBEDE Mo-93 8.5E-01 2.3E-03 6.7E-02 3.3E+00 3.lE-03 8.5E-06 2.5E-04 1.2E-02CN SCRP LANDFIL-N Nb-93m 4.7E-04 1.3E-04 4.0E-04 1.lE-03 1.8E-06 4.8E-07 1.5E-06 4.0E-06CN SCRP HANDLIN-W Nt>-94 7.3E+00 8.4E-03 4.6E-01 2.5E+01 2.7E-02 3.lE-05 1.7E-03 9.3E-02 CN SCRP-LANDFIL-N Nb-95 1.7E+00 6.0E-01 1.7E+00 3.4E+00 6.4E-03 2.2E-03 6.2E-03 1.2E-02CN SCRP-TRANSPO-W
" W.Y Tc-99 2.6E+00 1.9E-02 4.lE-01 9.5E+00 9.5E-03 7.lE-05 1.5E-03 3.5E-02CN-SCRP LANDFIL-N Ru-103 1.1E+00 3.9E-01 1.1E+00 2.2E+00 4.1E-03 1.4E-03 3.9E-03 8.0E-03 CN-SCRP-TRANSPO-W Ru-106 4.9E-01 1.7E-01 4.7E-01 9.4E-01 1.8E-03 6.3E-04 1.7E-03 3.5E-03 CN-SCRP-TRANSPO-W Ag-108m 4.3E+00 5.0E-03 2.5E-01 1.4E+01 1.6E-02 1.9E-05 9.2E-04 5.lE-02 CN-SCRP-LANDFIL-N I SCRP-ROADQy b - .
7-13 Draft NUREG-1640, Vol.1
Evaluation of Concrete Section 7 Table 7.3 Concrete recycle critical-group dose factors-surficial (pSv/y per Bq/cm2 ) (mrem /y per pCi/cm ) 2 90% Confidence interval "' # g; Critical-group 5* 50* 95* group 5* 50* 95* dose (lower (median) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Ag-ll0m 6.7E+00 2.3E+00 6.4E+00 1.3E+0! 2.5E-02 8.7E-03 2.4E-02 4.8E-02CN-SCRP TRANSPO-W Sb-124 4.3E+00 1.5E+00 4.lE+00 8.3E+00 1.6E-02 5.6E-03 1.5E-02 3.lE-02 CN-SCRP-TRANSPO-W I-125 7.lE-03 1.9E-03 6.0E-03 1.6E-02 2.6E-05 6.9E-06 2.2E-05 5.9E-05 CN-SCRP-ROADBED-W Sb-125 9.6E-01 3.3E-01 9.2E-01 1.8E+00 3.5E-03 1.2E-03 3.4E-03 6.8E-03 CN-SCRP-TRANSPO-W WhhESh5$h$$ SS b0 1-131 6.5E-01 2.lE-01 6.lE-01 1.3E+00 2.4E-03 7.7E-04 2.2E-03 4.6E-03CN-SCRP TRANSPO-W Ba-133 6.6E-Ol 2.3E-01 6.3E-01 1.3E+00 2.4E-03 8.5E-04 2.3E-03 4.7E-03 CN SCRP TRANSPO-W Cs-134 3.8E+00 1.3E+00 3.6E+00 7.2E+00 1.4E-02 4.9E-03 1.3E-02 2.7E-02 CN-SCRP-TRANSPO-W Cs-137 1.5E+00 5.lE-01 1.4E+00 2.8E+00 5.4E-03 1.9E-03 5.lE-03 1.0E-02 CN-SCRP-TRANSPO-W 8 2 % y ]<02.2Ep2f2,.1E-01, ,[k,,3(8E-05s2.3MgM@]h_(hk Cc-144 7.8E-02 2.7E-02 7.4E-02 1.5E 01 2.9E-04 1.0E-04 2.7E-04 5.5E-04 CN-SCRP-TRANSPO W Pm 147 4.4E-04 1.0E-04 3.6E-04 1.2E-03 1.6E-06 3.8E-07 1.3E-06 4.3E-06 CN-SCRP-ROADBED-W Eu-152 2.6E+00 9.lE-01 2.5E+00 5.0E+00 9.7E-03 3.4E-03 9.3E-03 1.9E-02 CN-SCRP-TRANSPO-W Eu 154 2.9E+00 1.0E+00 2.7E+00 5.5E+00 1.lE-02 3.7E-03 1.0E-02 2.0E-02 CN-SCRP-TRANSPO-W
- m. 7 ., w m v n .- , ,,,. ,. w -~, .n - . , m - w.nn. . .-. ..m ., n. - ,., v.a.n ~ . e -
y . Es-155M 5.'8Ey2[9.9E-0M 4.5E-02n5E-01, '2.lE-04,,q3.M5)LI.7Fe0405.4E 04}CN-SCRP-ROADBED @ Re-186 7.2E-03 2.0E-03 6.4E-03 1.5E-02 2.7E-05 7.3E-06 2.4E-05 5.7E-05 CN SCRP-TRANSPO-W Ir 192 1.7E+00 5.9E-01 1.6E+00 3.3E+00 6.2E-03 2.2E-03 5.9E-03 1.2E-02 CN-SCRP-TRANSPO-W Pb-210 1.6E-01 6.2E-01 1.7E+00 1.7E+00 2.7E-03 5.9E-04 2.3E-03 6.4E-03 CN-SCRP-HANDLIN W Po-210 7.4E-02 2.6E-01 6.9E-01 6.9E-01 1.lE-03 2.7E-04 9.7E-04 2.5E-03 CN-SCRP-HANDLIN W [2M1(2h 36h [FEYb3s5 78. M 5S N M k [i h h [S $, [1E O $ Rn-222 2.5E+00 6.8E-01 2.2E+00 5.3E+00 9.2E-03 2.5E-03 8.3E-03 2.0E-02 CN-SCRP-TRANSPO-W Ra-223 4.5E-01 1.5E-01 4.3E-01 8.7E-01 1.7E-03 5.6E-04 1.6E-03 3.2E-03 CN-SCRP TRANSPO-W Ra-224 1.8E+00 4.9E-01 1.6E+00 3.8E+00 6.6E-03 1.8E-03 6.0E-03 1.4E-02 CN-SCRP TRANSPO-W Ac-225 3.6E-01 1.2E-01 3.4E-01 6.9E-01 1.3E-03 4.4E-04 1.2E-03 2.6E-03 CN-SCRP-TRANSPO-W
. .- r .~ , e e nn- ~~.~ - n..,,,.-m.~,
Ra-22$m me:-- gl.2E-01(3.3E - mm-,wmm 02al.1E 0g2.7E-01 . 4.5E-04 nl.2Fr0403.9E-04410E-03h-SCRP.-HAND 13N,-E Ra-226 1.3E+01 2.4E-02 1.0E+00 5.0E+01 4.8E-02 9.0E-05 3.7E-03 1.8E-01 CN-SCRP-LANDFIL N Ac-227 2.0E+01 4.8 E+00 1.6E+01 4.6E+01 7.2E-02 1.8E-02 6.lE-02 1.7E-01 CN-SCRP-HANDLIN W Th-227 2.6E-01 7.2E-02 2.3E-01 5.8E-01 9.6E-04 2.7E-04 8.4E-04 2.lE-03 CN-SCRP-HANDLIN-W Th-228 6.3 E+00 1.6E+00 5.2E+00 1.4E+01 2.3E-02 5.8E-03 1.9E-02 5.3E-02CN-SCRP ROADBED-W h k [ME .k [0EM EM3ETGYi[' 3 hMhhhk; Th-229 3.3E+01 3.8E-02 2.lE+00 1.2E+02 1.2E-01 1.4E-04 7.7E-03 4.5E-01 CN-SCRP-LANDFIL-N j n-230 5.3E+00 6.3E-03 3.4E-01 1.9E+01 2.0E-02 2.3E-05 1.3E-03 7.lE-02CN-SCRP-LANDFIL-N l I Pa-231 5.0E+0! 7.6E-02 3.7E+00 1.9E+02 1.9E-01 2.8E-04 1.4E-02 7.2E-01 CN SCRP-LANDFIL-N Th-231 9.2E-04 5.8E-05 4.7E-04 3.5E-03 3.4E-06 2.2E-07 1.8E-06 1.3E-05 CN-SCRP-TRANSPO-W j m mm _ ki2 isiiWR3_~.s_siWT.i__m~5._s.%st_is._ m W E_d17. 15 M s'si M, is.di p Y a s.' N F15 s n _sEf2 u. I Draft NUREG-1640, Vol. I 7-14 l
r 1 Section 7 Evaluation of Concrete N Table 7.3 Concrete recycle critical-group dose factors-surficial (pSv/y per Bq/cm )3 (mrem /y per pCi/cm ) 90% Confidence interval 90% Confidence interval Critical- ,, group 5* 50* 95* group 5* 50* 95* dose (lower (rnedian) (upper dose (lower (median) (upper Radionuclide factor bound) bound) factor bound) bound) Scenario Pa 233 3.2E-01 1.lE-01 3.lE-01 6.lE-01 1.2E-03 4.!E-04 1.lE-03 2.3E-03 CN-SCRP-TRANSPO-W U-233 3.8E+00 1.3E-02 3.4E-01 1.3E+01 1.4E-02 5.0E-05 1.3E-03 4.9E 02CN-SCRP-LANDFIL-N l Th 234 1.8E-02. 6.lE-03 1.7E-02 3.4E-02 6.5E-05 2.2E-05 6.3E-05 1.2E-04CN-SCRP-TRANSPO-W U-234 3.8E+00 9.7E-03 3.5E-01 1.4E+0! 1.4E-02 3.6E-05 1.3E-03 5.2E-02 CN-SCRP LANDFIL-N A $ Np 237 1.4E+03 1.6E+00 8.3E+01 5.0E+03 5.2E+00 5.9E-03 3.lE-01 1.9E+01 CN-SCRP-LANDFIL-N Pu 238 4.0E+00 9.2E-01 3.3E+00 1.0E+01 1.5E-02 3.4E-03 1.2E-02 3.7E-02CN SCRP-HANDLIN W ! U-238 3.lE+00 8.9E-03 3.4E-01 1.lE+0i 1.lE-02 3.3E-05 1.3E-03 3.9E-02CN-SCRP LANDFIL N Pu 239 5.4E+00 6.9E-03 3.4E-01 2.0E+01 2.0E-02 2.5E-05 1.3E-03 7.5E-02 CN-SCRP-LANDFIL-N j M h ike01 @ I9Edbi.k+]0 Pu 241 2.0E-02t 2.7E 05E13B.Sk 4.0E 01 3.4E-04 1.8E-02 1.6E+00 1.5E-03 1.3E-06 6.8E-05 5.8E 03 CN-SCRP-LANDFIL-N [ 1 { Am 241 8.0E+00 1.lE 02 5.lE-01 3.lE+01 3.0E-02 4.lE-05 1.9E-03 1.2E-01 CN SCRP LANDFIL-N $ Cm 242 2.5E-01 5.9E-02 2.lE-01 6.0E-01 9.2E-04 2.2E-04 7.6E-04 2.2E-03 CN-SCRP-HANDLIN W Pu 242 ~ 5.lE+00 6.2E-03 3.3E-01 1.9E+01 1.9E-02 2.3E-05 1.2E-03 7.lE-02CN SCRP-LANDFIL N j Cm 244 3.7E+00 8.8E-01 3.lE+00 8.8E+00 1.4E-02 3.3E-03 1.lE-02 3.3E-02CN SCRP HANDLIN-W The ratio of the 95* to the 5* percentile is a useful measure of the relative width of the 90% confidence interval for comparison between scenarios. Smaller values of the 95/5 ratio indicate less uncertainty than larger values. The scenarios with the smallest uncertainty are those with the fewest number of exposure pathways and the least uncertainty in the parameters describing those pathways. The scrap transportation scenario accounts for 33 of the 85 radionuclides. It has the smallest uncertainty of all the critical group scenarios with a 95/5 ratio of about 2 for most radionuclides. The sources of uncertainty in this scenario are similar to those for the steel scrap transportation scenario discussed in Section 4.9. For all scenarios that take place subsequent to the initial transport of scrap, additional sources of uncertainty are introduced and wider confidence intervals result. Scenarios that address handling concrete scrap or using it in rosdbed construction include uncertainty due to mixing with other scrap. They also include additional exposure pathways-inhalation of suspended dust and inadvertent ingestion under dusty conditions. For concrete, this group of handling and construction scenarios have 95/5 ratios that range from about 5 to about 35. The landfill resident scenario is limiting for 28 radionuclides. Uncertainty in this scenario includes contributions from the ground water transport model and pathways for ingestion, inhalation, and external exposure. Dose factors for nuclides limited by this scenario have 95/5 ratios that range from about 500 to about 6500 and are typically about 2000. This is due to the uncertainties associated with the groundwater transport model and the timing of the scenario. (n Over the period of time addressed by this scenario there is a large uncertainty in the rate at which 7-15 Draft NUREG-1640, Vol. I
I I Evaluation of Concrete Section 7 l l each radionuclide teaches to the drinking water supply and in the resulting concentration in l drinking water. Some radionuclides undergo significant radioactive decay and some have ) radioactive progeny that are increasing over this time scale. Uncertainty in timing is magnified j by the exponential processes of radioactive decay and progeny ingrowth. l The mean values of the derived surficial dose factors for each radionuclide in Table 7.3 represent j the dose to the average member of the critical group exposed to radioactivity initially distributed I over the surface of cleared concrete scrap (Bq/cm 2 or pCi/cm2 ). Derived surficial dose factors l are calculated from mass-based dose factors by use of a surface-to-mass ratio appropriate for j concrete slabs of typical thicknesses. The surface-to-mass ratio is used to derive surficial dose j factors as described in Section 4.7. j The calculation of derived surficial dose factors is probabilistic. The parameter SM is l represented by a distribution of values that incorporate the variability and uncertainty in the j surface-to-mass ratio of typical concrete slabs available for clearance. This additional source of uncertainty results in wider confidence intervals for the surficial dose factors than for the mass-based dose factors from which they are derived. The relative importance of this additional uncertainty depends on the scenario. The uncertainty in the surface-to-mass ratio is somewhat larger for concrete slabs than for typical steel, copper, and aluminum objects due to the wide range of slab thicknesses and the variability in the density of concrete. For this reason, the confidence intervals for derived surficial dose factors are relatively wider for concrete relative to the mass-based dose factors. For scenarios with the narrowest confidence intervals, the added uncertainty can result in confidence intervals about three times wider than the corresponding mass-based dose factors. The mass-based dose factor for the scrap transportation scenario has a 95/5 ratio of about 2 for most radionuclides. The ccrresponding derived surficial dose factors have a 95/5 ratio of about 6. The added uncertainty in surface-to-mass ratio has a relatively smaller impact on the confidence interval for scenarios with larger uncertainties, contributing an j additional 50% to 100% for the scrap handling and roadbed construction scencrios. For the j landfill resident scenario the uncertainty in surface-to mass ratio is small compared to the uncertainties in the ground water model and ingestion dose pathways. For this scenario, the 95/5 I ratio for the derived surficial dose factors ranges from zero to about 30% hcger than for the ; corresponding mass-based dose factors. )I l l l l l Draft NUREG-1640, Vol. I 7 16 O
p-8 QUALITY CONTROL PROGRAM in order to ensure that the reuse and recycle assessments are defensible, accurate, and verifiable, a Quality Control Plan (QCP) was prepared and followed during conduct of this evaluation. The QCP includes specification ofprocedures and conventions adopted to implement quality control for the recycle and reuse modeling efforts. The QCP also describes requirements for model development, equation and parameter definitions, and spreadsheet implementation, and also specifically addresses requirements forpreparation, review, calculation checks, documentation, and cuord keeping of technicalinformation. The QCP therefore provides a documented system for ensuring accuracy of results, as wellas a basis for tracing assumptions. The QCPincorporated quality assurance guidelines provided by both the NRC and other recognized authoritative references. The pathway model components developed for this analysis served as the design description for spreadsheet software development. A Quality Assurance (QA) administrator ensured that appropriate steps were taken to implement the quality control, documentation and configuration management requirements of the analyses. The QA administrator acted as a centralhub for the reviewprocess; all materialpassed through the QA administrator for each step of the review and final documentation of technicalinformation. All technicalinformation developed forthe project waspeerreviewed. This included conceptual models, equations and spreadsheets. Specific items to be reviewed were indicated oo the review checklist that accompanied all review packets. In addition to in-house peer review, aspects of the analyses were peer reviewed by an outside consultant. This review function was to ensure technical adequacy and reasonableness of the analysis, interpretation of the results, and other aspects of the analysis. In order to meet the documentation requirements in an organized, retrievable manner, a formalsystem of document review and filing was implemented. The project QA administrator was responsible for
\ maintaining the organization and contents of the Project Engineering Cabinet, which served as a repository for the master versions of all controlled project documents. In addition, a system was implemented for assigning electronic file names, in order to maintain proper document control.
As described in Section 1, the purpose of this evaluation is to provide the technical basis for i implementing criteria for clearance of equipment and material from nuclear facilities licensed by the Nuclear Regulatory bmmission (NRC). A defensible dose assessment for rulemaking purposes must be accurate and verifiable. It must be supported by a quality assurance record of checks for errors in documentation, calculation, and transcription. In order to ensure that these elements are incorporated, a Quality Control Plan (QCP) was prepared and followed while conducting this evaluation. The QCP includes specification of procedures and conventions adopted to implement quality control for the recycle and reuse modeling efforts. The QCP also describes requirements for modei development, equation and parameter definitions, and spreadsheet implementation, as well as addressing requirements for preparation, review, calculation checks, documentation, and record keeping of technical information. The QCP, therefore, provides a documented system for ensuring accuracy of results, as well as a basis for tracing assumptions. The QCP was revisud and updated as the project progressed, in order to address changes in the technical requirements. O
\d 8-1 Draft NUREG-1640, Vol. I
i Quality Control Program Section 8 i The QCP identified the procedures and conventions that were adopted to implement quality control for the project. In keeping with the nature of the tasks, special emphasis was placed upon quality assurance for spreadsheet model development and documentation. The QCP incorporated quality assurance guidelines provided by the following references: NQA-l b-1987, Quality Assurance Program Requirementsfor Nuclear Facilities NQA-2a-l990 Quality Assurance Program Requirementsfor Nuclear Facilities ANSllANS-10.4, Guidelinesfor the Validation and Verification ofScientific and Engineering Computer Programsfor Nuclear Facilities NUREGlCR-0l67, Software Quality Assurance Program and Guidelines The QCP also discusses incorporation of the technical approach into the quality control guidelines. The remainder of this section describes information and criteria contained in the QCP. 8.1 Technical Approach to Model implementation As required by NRC, computer applications and models met the requirements of the NRC Policy and Procedures Manual, Section 2.2. Spreadsheet models were developed on PC-based platforms running proprietary, commercial software. Other commercially available software was used to precalculate " lumped" parameter values for use in the spreadsheet models. Prior to use, software was approved by the SAIC Task Manager and Project Manager. With only one exception, all of the codes listed below were run on personal computers (the MCNP code was run on a workstation). This listing does not include non-technical codes such as word processing or project management software. The following software applications were approved and used in this analysis. Crystal Ball 4.0 (Decisioneering 1996). Crystal Ball, a forecasting and risk analysis program, is used as an add-on to Excel. It uses the Monte Carlo sampling methods to calculate uncertainty in a model result. Crystal Ball will sample from an assumption cell in the Excel worksheet that contains a probability distribution defined by the user and calculate a range of possible outcomes in the forecast cell as well as the likelihood of achieving each of them. The Monte Carlo method, as used by Crystal Ball, is accomplished with three simple steps which are repeated for a set number of times defined by the user. These steps are (1) generating random numbers for assumption cells, (2) calculating the entire spreadsheet, and (3) displaying results in a forecast chart. This program was used as an uncertainty analysis tool. Excel 97 (SR-1) (Microsoft 1997). Excel is a general purpose, spreadsheet analysis application. Excel provides the tools necessary to perform data analysis, list-keeping, and calculations. Excel also enables the user to present the results efficiently. Worksheets enable the user to store, manipulate, calculate, and analyze data. Macros are also available in Excel, which enable the user to automate frequently performed tasks and perform specialized calculations. Excel was used as the platform for all calculations. Draft NUREG-1640, Vol. I 82 i
p l Section 8 Quality Control Program p MCNP (Briesmeister 1993). MCNP (Monte Carlo N-Particle) is a three-dimensional transport code which treats an arbitrary configuration of materials in cells bounded by surfaces. Pointwise, continuous-energy cross-section data are used. The transport equation is solved by the method of random w ' alk (Monte Carlo). Energy specific sources and response functions may be used to estimate dosimetric quantities ofinterest for virtually any configuration. MCNP was used to calculate all of the extemal exposure geometry factors except those obtained from Environmental l Protection Agency (EPA) documents. MicroShield 4 (Negin and Worku 1992a). MicroShield analyzes shielding and estimates exposure from gamma radiation. This version allows versatile geometries with offsets from axes of symmetry. Sensitivity analyses are available for dimensional variations within a single case. Results are calculated with and without buildup simultaneously. MicroShield has the capability to handle photon energies between .015 and 15 MeV. Data for attenuation coefficients, buildup factors, and buildup factor coefficients are obtained from information distributed by the Radiation Shielding Information Center and included in ANS 6.4.3. MicroShield was used in the development of uncertainty ranges for the geometry factors and occasionally as a quality assurance check for the geometry factors calculated with MCNP. l RadDecay 4 (Negin and Worku 1992b). RadDecay contains radioactive decay information for , 497 radionuclides. Data includes the half-lives, radioactive daughters, probabilities per decay, I and decay product energies for alphas, betas, positrons, electrons, X-rays, and gamma rays. p Given an initial radioactivity and decay time, RadDecay will calculate the remaining radioactivity of a radionuclide and the radioactivity level ofits progeny. The decay chain is calculated and displayed for up to 20 generations. Identical daughters generated along different branches of the parent decay chain are combined. RadDecay also has the capability to search for gammas and X-rays in a specific energy range set by the user (Negin and Worku 1992b). l RadDecay was used primarily to calculate ingrowth of radioactive progeny. RADTRAN 4 (Neuhauser and Kanipe 1994). The RADTRAN 4 code combines user-supplied input data with health physics data to calculate the expected radiological consequences and risks resulting from the transportation of radioactive material. Estimates of radiological consequences ard 4 , are derived by numerically modeling the path and behavior of each package from the
^ r aat transportation begins until it arrives at its destination.
8.2 Quality Requirements The exposure pathway model components developed for this analysis, including scenario descriptions, parameter tables, mathematical equations and pathway flow diagnuns, served as the design description for spreadsheet software development. All staffinvolved in model development were apprised of these quality control, documentation, and configuration management requirements, and a Quality Assurance (QA) administrator ensured that appropriate steps were taken to implement the requirements. Each model developer was responsible for assuring that the data and formulas encoded as spreadsheet models were accurate, complete, e 8-3 Draft NUREG-1640, Vol. I
Quality Control Program Section 8 verifiable, and properly documented. The basic quality requirements imposed on this analysis are listed below. The source and evolution of all model parameter values and algorithms must be documented. Documentation must be sufficient to permit the completion ofindependent verification and quality reviews and to allow ready verification of configuration management functions by audit. Documents and references necessary to establish the basis of a model must be maintained in the Project Engineering Cabinet. Design changes must be documented and traceable. Where appropriate, parameters and units must be named in a manner consistent with Section 2.2 of NUREG/CR-5512 (Kennedy and Strenge 1992) or Volume 3 of NUREG/CR-5512 (Beyeler et al.1996). Spreadsheet applications must contain sufficient internal documentation so that users do not have to consult external manuals for routine operation of the spreadsheet. If extemal manuals or other documents are necessary, the spreadsheet must contain complete citations for these documents. Documentation must be sufficient to permit a user to identify and track any changes to the spreadsheet made under the configuration control procedures. Spreadsheets must conform to a standard structure, consisting of a title page followed by several principal sections. The banner / title page must identify the model, the version number, and the responsible author. The spreadsheet must also contain a workbook or spreadsheet description, macro fields and macro listings. Another section of the spreadsheet must list the parameter names, symbols, units, default values, as wcll as references that are applied in the spreadsheet. Ancther section must contain the data input fields for radionuclide-independent and dependent parameters. The calculational fields of the model must be delineated in another section. Other sections of the spreadsheet must be identified as needed. Numeric formats must be consistent. Appropriate significant figures should be used for final results. To the extent practicable, standard functions within the spreadsheet applications software should be used in lieu of custom functions. To the extent practicable, if custom functions are used, they will be consistently applied to all calculations performed. Draft NUREG-1640, Vol. I 84 O
l Section 8 Quality Control Program { 8.3 Document Review, Control and Configuration Management l In order to meet the documentation requirements in an organized, retrievable manner, a formal system of document review and filing was implemented. A QA administrator acted as a central hub for the review process; all material passed through the QA administrator for each step of the review and final documentation of technical infonnation.
- When a scenario model, material flow description, or other technical description was sufficiently developed, the author was responsible for transmitting a packet containing descriptions, references and electronic copies to the project QA administrator for document control. The QA Administrator would then review the submittal for completeness, log-in and file the model, and submit the packet for peer review.
Because of the complexity of many of the spreadsheet models in this analysis, documentation and review of the scenario descriptions were completed prior to encoding the spreadsheet. 8.4 QA Review of Technical Information
' All technical information developed for the project was peer-reviewed. This included conceptual models, equations and spreadsheets. Specific items to be reviewed were indicated on the review checklist that accompanied all review packets. ,
O I Q The QA review for a new or revised version of a spreadsheet model included, at a minimum, a review of the following six elements: parameters, benchmark check, calculation model, l documentation, transcription, and verification. Parameter values were checked against sources for accuracy and transcription; documentation was checked for completeness. Verification involved a check of whether or not the mathematical model r.lgorithms were accurately implemented. Benchmark checks included a comparison of the computation results of a specific spreadsheet or workbook with the results (printed version) of a reference spreadsheet or workbook used to analyze the same or comparable problem. QA reviews ofinterim revisions were limited in scope, but were sufficient to address the documented changes. In addition to in-house peer-review by SAIC technical personnel, the analyses were peer-reviewed by an outside contractor. This review function was to ensure that the analyses were reasonable and technically adequate and the results were interpreted satisfactorily.
8.5 Recordkeeping
Project Engineering Cabinet The project QA administrator was responsible for maintaining the organization and contents of the Project Engineering Cabinet, which served as a repository for the master versions of all controlled project documents. Individual files were separately labeled and coded by the QA Administrator, and the cabinet was organized to include the sections outlined below. 8-5 Draft NUREG-1640, Vol. I
Quality Control Program Section 8 Master Directory ,.. The master directory contained information applicable to all aspects of the project. This includes master scenario lists, document status tables, procedures, and general project information. The master directory served as a key section of the project engineering cabinet and is the starting point for anyone looking for specific technical information about the project. Scenario Files The scenario is a primary, organizational unit for this analysis. As such, project documentation and quality review functions were structured around scenario development. Documentation of the description, modeling, and review for each scenario was maintained as a unit: a discrete file in the project engineering cabinet. A completed scenario file contains all descriptions, documents, and forms indicated for that individual scenario. It includes a full-version history of the model and provides for traceability of configuration control, model validation, and other elements of the QA review. Scenario model development usually proceeded in three stages, where the conceptual framework and mathematical representation of the scenario model was completed and reviewed prior to encoding the deterministic model into a spreadsheet. In turn, encoding and review of the deterministic model served as the basis for probabilistic modeling. This process was reflected in the Engineering Cabinet documentation. The file structure described above for printed documents in the cabinet is duplicated for electronic versions of the scenario files. A controlled electronic media repository was maintained by the QA Administrator. Each electronic file was assigned a unique,8-character name according to the conventions described in Section 8.6. Three-digit file extensions (e.g.,*.xxx) were used to indicate individual document types and revision numbers maintained in the scenario file. For example, the scenario file for the transportation of dust was labeled as tduG3fei. The original (revision 0) scenario spreadsheet was labeled as tduG3fei.ds0. Material Flow Files The Material Flow section contains all the information used to develop the conceptual and mathematical models, as well as the initial version and supporting documentation, for the material flow. For purposes of project documentation and qu'ality review, material flow models and spreadsheets were considered to be the same as scenario models, and met the same set of requirements. Information in this section also contains the original review checklist form attached to the appropriate material. Background Documentation Files Background documentation refers to technical information about the project that does not clearly fall into one of the other specified sections of the Engineering Cabinet. An Engineering Design Draft NUREG-1640, Vol. I 8-6 9 l 1
n.- l Section 8 Quality Control Program l ,o File (EDF) system provided a formal structure for document review and control for additional technical descriptions and reference documents that needed to be included in the project files. l For instance, the EDF format was used to document the technical development and justification of parameters such as the surface-to-mass ratios. All background documents to be reviewed or filed required an EDF coversheet followed by the body of the report, references, and any appendices. A completed EDF coversheet included the l EDF log number (assigned by QA Administrator), the report title, a report summary, and signatures of all authors and reviewers. Geometry Factor Files The Geometry Factors section of the Engineering File Cabinet contains details of the calculations needed to develop Geometry Factors for the scenarios evaluated. The Geometry Factor is a
" lumped parameter," therefore, the content of this file se-tion is different than other sections of the cabinet, but still contains a complete documentation record.
Quality Assurance Administration Files The Project QA Doctunentation section contains the quality assurance documents for the overall project (i.e., the Project Quality Control Plan with all the attached appendices). The QA Forms .g section also contains all completed QA forms (i.e., spreadsheet QA form). The QA forms were l l printed on colored paper so they were easy to identify. ! Project Management Files The Project Management section was for items such as monthly reports, memoranda, and other items applicable to various aspects of management of the project. j l Report Files j The Report section contains all draft and final versions of formal reports produced for the NRC ! as part of this analysis. References i All references that are used are kept in the Reference section. f 8.6 Instructions for Naming Files and Scenarios t
\
r The following criteria were used when assigning electronic file names to scenario files for this j evaluation. In general, the first eight file characters are reserved for each of the following six ; g classifications: scenario category, material type, restricted or unrestricted uses, scenario ,
! )
V l 8-7 Draft NUREG-1640, Vol.1 i L'
Quility Control Program Section 8 description number, initial product material type, and target population. The final criterion specifies the file extension criteria.
- 1) The first character was reserved for the scenario category. The following scenario categories have been identified:
h = handling and processing d = disposal s = storage t = transportation p = product use x = applies to all categories
- 2) The second character was reserved for the product material type. The following material types have been identified:
a = atmospheric emission d = dust and dust byproducts - m = scrap metal r = refined metal product i s = slag from steel refining x = applie: to all end product l material types
- 3) The third character was reserved for designding whether the scenarios is a restricted use or an unrestricted use scenario, as follows:
r = restricted use u = unrestricted use x = all uses Note: " Restricted" and unrestricted" terms were used in the early phases of this analysis, but were dropped during the course of the analysis. There are no " restricted use" scenarios evaluated, so this character is unnecessary.
- 4) The fourth and fifth characters were reserved for a scenario description r. umber (1-99).
This number can be cross-referenced to the Scenario Description Table to provide a complete scenario description.
- 5) The sixth and seventh characters were reserved for the initial product material being reused or recycled. Standard chemical symbols were used when possible:
al = aluminum fe = iron / steel cu = copper en = concrete xx = applies to all initial product materials
- 6) The eighth character was uss3 to identify the target population, using the following abbreviations:
i = onsite worker, individual o = onsite worker, population g = general pub!ic, individual p = general public, population v = visitor, individual x = applies to all target populations Draft NUREG-1640, Vol. I 8-8 O l a- _ _ _ - _ _ _ _ _ . _ _ _ _
' Section 8 Quality Control Program
- 7) File extensions reflected the document type and revision number (used only for exposure i scenarios). The first and second characters indicate the document type and the third 1
\
character indicates the revision number:
- pd# '= probabilistic description, revision number #
- dd# = deterministic description, revision numbei #
- ps# = probabilistic spreadsheet, revision number #
- ds# = deterministic spreadsheet, revision number #
Following the above file naming criteria, file tduG3fei.ddl is the first revision of a deterministic scenario description and technicaljustification for the unrestricted transportation of dust. This scenario is the third in the transportation category, thus it has a scenario description number of
- 03. The initial source material being recycled is steel. The dose is evaluated for an individual onsite worker.
For the purposes of this report, additional scenario abbreviaticns were developed. The use of these abbreviations does not affect the electronic file name.;. A cross-reference between the two sets of file names is i~n cluded in Appendix A. L I U 8-9 Draft NUREG-iti40, Vol. I l
l 1 1 Lp- 9 - REFERENCES L. AEC,1974. Termination ofOperating Licensesfor Nuclear Reactors, Regulatony Guide 1.86. U.S. Atomic Energy Commission, 'Nashington, D.C., June 1974. AIHC,1995. Exposure Factors Source Book. American Industrial Health Council, Washington, D.C.,1995. AIHC,1994. Exposure Factors Source Book. American Industrial Health Council, Washington, t D.C., May 1994. L AISE,1993. Directory: Iron andSteelPlants 1993. Association ofIron and Steel Engineers, Pittsburgh, Pennsylvania,1993l AISI,1998. American Iron and Steel Institute data cited in promotional material for Florida Steel Homes, Inc., May 28,1998 (on the Internet at http://www.floridasteelhome.com/ ststistics.htm). l Anspaugh, L.R., et al.,1974. "Eva' on of the Resuspension Pathway Toward Protective l Guidelines for Soil Contant,:ation with Radioactivity," International Atomic Energy i Agency /World Health Organization Symposium on Radiological Safety Evaluation of ! Population Doses and Application ofRadiological Safety Stanaards to Man and the f Environment. Portoar, Yugoslavia, May 20-24,1974. IAEA, Vienna,1974. Bames, D.E.,1959. " Basic Criteria in the Control of Air and Surface Contamination," Symposium on Health Physics in Nuclear Installations, at Rise, Denmark, 25-28 May ' 1959. Organization for European Economic Cooperation / European Nuclear Energy , I Agency, Paris,1959. Bever, M.B.(editor-in-chief),1986. Encyclopedia ofMateria!s Science and Engineering, Volume 2. MIT Press, Cambridge, Massachusetts,1986. Beyeler, W.E., et al.,1996. Residual Radioactive Contaminationfrom Decommissioning: Parameter Analysis, Draftfor Review, NUREG/CR-5512, Volunw 3. Prepared by Sandia L National Laboratories for the U.S. Nuclear Regulatory Commissic', April 25,1996 (on the Intemet at http://techconflini. gov /radcri/ java.html via the hypctlinks D. o g Assessment and NUREG!CR-5512. Vol. 3).' BLS,1998. Information from the Occupational Outlook Handbook, downloaded from the Bureau of Labor Statistics website on April,3,1998 (http:// stats.b/s. gov /oco). V _ . _ . . 9-1 Draft NUREG 1640. Vol. I
References Section 9 Briesmeister, J. F.,1993. AfCNP-A General Monte Carlo N-Particle Transport Code, Version
./A, LA-12625-M. Los Alamos National Laboratory, Los Alamos, New Mexico, November 1993.
Dwlsky, A.,1980, "Resaspension Factors and Probabilities ofIntake of Material in Process (or
'Is 104 a Magic Number in Health Physics?')." Health Physics, Volume 39, pp.
992-1000, December 1980. Brough, J.R., and W.A. Carter,1972. " Air Pollution Control of an Electric Furnace Steelmaking Shop." Journal ofthe Air Pollution Control Association, Volume 22, No. 3, March 1972. Brown, R.E.,1993. Mineral,1:arbook,1992: Iron andSteelScrap. U.S. Bureau of Mines, Washington, D.C., October 1993. Brunskill, R.T.,1964. "The Relationship Between Surface and Airborne Contamination," Surface Contamination, Proceedings ofa Symposium Held at Gatlinburg, Tennessee, June 196./. Pergamon Press, Oxford,1967. Butts, A. (editor),1970. Copper: The Science and Technology ofthe Metal, its Alloys and Compounds. Hafner Publishing Company, Inc., New York,1970. Cass, R.W., and J.E. Langley, l977. Fractional Efficiency ofan Electric Arc Furnace Baghouse, EPA-600/7-77-023. U.S. Environmental Protection Agency, Washington, D.C., March 1977. Charles, D., and G.M. Smith,1992. " Waste Management Study for Large Volumes of Very Low Level Waste from Decommissioning of Nuclear Installations." IE2713-5, Version 2. Prepared by Intera Information Technologies for Commission of European Communities, Oxfordshire, U.K, December 1992. Chen, S.Y.,1993. Risk Assessment Based on Current Release Standardsfor Radioactive Surface Contamination. ANL/EAIS/CP-79677. Argonne National Laboratory, Argonne, Illinois, September 1993. Chen, W.F. (editor),1995. Civil Engineering Handbook. CRC Press, Cleveland, Ohio,1995. Copeland, G.L., R.L. Heestand, and R.S. Mateer,1978. Volume Reduction ofLow-Level Contaminatcd Metal Waste by Melting-Selection ofMethod and Conceptual Plan, ORNL/TM-6388. Oak Ridge National Laboratory, Oak Ridge, Tennessee, June 1978. Cowher! C., R. Bohn, and T. Cuscino,1979. Iron andSteel Plant Open Source Fugitive Emission Evaluation, EPA-600/2-79-103. Midwest Research Institute, Kansas City, Missouri, May 1979. Draft NUREG-1640, Vol. I 9-2 O
Section 9 References n CRC,1992. D. Lide (editor-in-chief), Handbook ofChemistry and Physics, 73rd edition (1992-1993), pp.15-38. CRC Press, Cleveland, Ohio,1992. Cuscino, T.A., l979. Particulate Emission Factors Applicable to the Iron andSteelIndustry, EPA-450/4-79-028. U.S. Environmental Protection Agency, Washington, D.C., September 1979. Decisioneering,1996. Crystal Ball Version 4.0 User Manual. Decisioneering, Inc., Denver, Colorado,1996. i Deckert, A.. R. Graf, and R. Gortz,1992. " Radiation Exposure to the General Public fmm Reclaimed Metals Out of Nuclear Facilities," Proceedings ofthe Symposium on Waste l Management, Tucson, Arizona, March 1-5,1992, Volume 2, pp.1809-1814. Arizona \ Board of Regents, Tucson,1992. l Dehmel, J.C., D. Loomis, J. Mauro, and M. Kaplan,1994. Characterization ofClass A Low- I I Level Radioactive Waste 1989-1990. Volumes 1-7, NUREG/CR-6147. Prepared by S. Cohen & Associates, Inc. and Eastern Research Group, Inc., for the U.S. Nuclear Regulatory Commission, Washington, D.C., January 1994. Doty. S.R., and B l'. Wallace,1976. A Climatological Analysis ofPasquillStability Categories Basedon ' Star' Summaries. National Oceanic and Atmospheric Administration, Washington, D.C., April 1976. 1 Dunster, H.J.,1964. "The Concept of Derived Working Limits for Surface Contamination," in Surface Contamination, Proceedings ofa Symposium Held at Gatlinburg, Tennessee, j June 1964. Pergamon Press, Oxford,1967. ' Dyer, N.C.,1995. " Radionuclides in United States Commercial Nuclear Power Reactors." Radiation Protection Management, Volume 12, No.1, January / February 1995. l l EC,1998. " Radiation Protection 89-Recommended Radiological Protection Criteria for the l l Recycling of Metals from the Dismantling of Nuclear Installations." European Commission, Office for Official Publications of the European Communities, Luxembourg, 1998. Elert, M., and M. Wiborgh,1992. " Basis for Criteria for Exemption of Decommissioning Waste: Reprocessing af Dust from Recycling of Steel," KEMAKTA AR 92-08. Kemakta Konsult
. AB, Stockho' , June 1992.
EPA 1997a. TechnicalSupport Document: Evaluation ofthe Potentialfor Recycling ofScrap Metalsfrom Nuclear Facilities (Review Draft). U.S. Environmental Protection Agency,
- Washington, D.C., March 11,1997. -[s\
Y 93 Draft NUREG-1640, Vol. I
Refermc;s Section 9 EPA,1997b. Guiding Principlesfor Monte Carlo Analysis, EPAl630lR-97/00l. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Washington, D.C., March 1997. EPA,1995. Profle ofthe Nonferrous Metals Industry, EPA 310-R-95-010. U.S. Environmental Protection Agency, Washington, D.C., September 1995. EPA,1993a. External Exposure to Radionuclides in Air, Water, undSoil. Federal Guidance Report No.12, EPA 402-R-93-081. U.S. Environmental Protection Agency, Office of Radiation and Indoor Air, Washington, D.C.,1993. EPA,1993b. Solid Waste DisposalFacility Criteria TechnicalManual, EPA 530-R-93-017. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, Washington, D.C.,1993. EPA,1991. Clean Air Act Assessment Package (CAP 88-PC). U.S. Environmental Protection Agency, Washington, D.C.,1991. EPA,1989a. Exposure Factors Handbook, EPA /600/8-89/-43. U.S. Environmental Protection Agency, Office of Health and Environment, Washington, D.C.,1989. EPA,1989b. Technical Guidance Document: Final Covers on Hazardous Waste Landfils and Surface Impoundments, EPA 530-SW-89-047. U.S. Environmental Protection Agency, Office of Solid Watte and Emergency Response, Washington, D.C.,1989. EPA, 1988. Limiting Values ofRadionuclide intake and Air Concentration and Dose Conversion Factorsfor Inhalation, Submersion, andIngestion, Federal Guidance Repott No.1l, EPA-520/1-88-020. U.S. Environmental Protection Agency, Office of Radiation Programs, Washington, D.C.,1988. EPA,1986. Iron and SteelIndustry Particulate Emissions Source Category Report, EPA /600/7-86/036. U.S. Environmental Protection Agency, Office of Research and Development, Washington, D.C., October 1986. EPA,1977. Proposed Guidance on Dose Limitsfor Persons Exposed to Transuranium Elements in the General Environment. U.S. Environmental Protection Agency, Office of Radiation Programs, Criteria and Standards Division, Washington, D.C. ,1977. EPRI,1993. Electric Arc Furnace Dust -1993 Overview, CMP Report No. 93-1. Prepared by Arthur D. Little and the Center fh: Materials Production, Carnegie Mellon Research Institute, Pittsburgh, Pennsylvania, July 1993. Draft NUREG-1610, Vol. I 9-4 O
p Section 9 References F enton, M.,' 1996. Minerals Yearbook.1995: Iron andSteelScrap. U.S. Bureau of Mines and U.S. Geological Survey, Washington, D.C.,1996. l 3O Fuchs, R.L,. and S.D. Mcdonald, 1993.1992 State-by State Assessment ofLow-Level ,
- Radioactive Wastes Received at Commercial Disposal Sites, DOEILLW-181. Department \
of Energy, Washingten, D.C., September 1993. LGibson, J.A.B., and A.D. Wrixon,1979. " Methods for the Calculations of Derived Working i L Limits for Surface Contamination by Low-Toxicity Radionuclides." Health Physics, Volume 36, pp. 311-321, March 1979, Harvey, D.S.,1990. " Melting of Contaminated Steel Scrap from Decommissioning,"in
' Decommissioning ofNuclear Installations. Elsevier Applied Science, London and New !
York,1990. Healy, J.W.,1980. " Review of Resuspension Models," in W.C. Hanson (editor), Transuranic ; Elements in the Environment. Technical Information Center, U.S. Department of Energy, ! Oak Ridge, Tennessee,1980. I Healy, J.W.,1971. Surface Contamination: Decision Levels, LA-4558-MS. Los Alamos Scientific Laboratory, Los Alamos, New Mexico, September 1971. Horst, T.W.,1982. "The Estimation of Airbome and Surface Contamination Resulting frcm the Deposition-Resuspension Process." Health Physics, Volume 43, No. 2, pp. 269-272, August 1982. IAEA,1996. Clearance Levelsfor Radionculides in SolidMaterials, Application el Exemption Principles, IAEA-TECDOC-855. Intemational Atomic Energy Agency, Vienna, ; January 1996. l
~ lAEA,1992. Application ofExemption ofPrinciples to the Recycle and Reuse ofMaterialsfrom Nuclear Facilities, Safety Series No.111-P-1.1. International Atomic Energy Agency, Vienna,1992.
IAEA,1989. Evaluating the Reliabili.y ofPredictions Made Using Environmental Transfer Models, Safety Series No.100. Intemational Atomic Energy Agency, Vienna,1989. lAEA,1970. -Monitoring ofRadioactive Contamination on Surfaces, Technical Report Series No. 120. International Atomic Energy Agency, Vienna,1970. ICRP 1994. Human Respiratory Tract Modelfor Radiological Protection, Publication No. 66. Intemational Commission on Radiological Protection, Pergamon Press, New York,1994. I 9-5 Draft NUREG-1640, Vol. I
References Section 9 ICRP, l978. Limitsfor intakes ofRadionuclides by Workers, Publication No. 30. International Commission on Radiological Protection, Pergamon Press, Oxford /New York, July 1978. ICRP 1974. Report ofthe Task Group on Reference Afan, Publication No. 23. International Commission on Radiological Protection, Pergamon Press, Oxford,1975. Jeffery, J., and J. Vay,1986. Iron and SteelIndustry Particulate Emissions: Source Category Report, EPA /600/7-86/036. U.S. Environmental Protection Agency, Washington, D.C., October 1986. Jones, I.S., and S F. Pond,1964. "Some Experiments to Determine the Resuspension Factor of Plutonium from Various Surfaces," in Su / ace Contamination, Proceedings ofa . Symposium Held at Gatlinburg, Tennessee, June 196-1. Pergamon Press, Oxford,1967. ! Kalyoncu, R.S.,1996. Afinerals Yearbook.1995: Slag-Iron andSteel. U.S. Bureau of Mines and U.S. Geological Survey, Washington, D.C.,1996. Kennedy, W.E., Jr., et al.,1981. A Review ofRemovable Surface Contamination on Radioactive Afaterials Transportation Containers, NUREG/CR-1858, PNL-3666. Prepared by Pacific Northwest Laboratory for the U.S. Nuclear Regulatory Commission, Washington, D.C., May 1981. Kennedy, W.E., Jr., and D L. Strenge.1992. Residual Radioactive Contaminationfrom Decommissioning: Volume 1, Technical Basisfor Translating Contamination Levels to Annual Total Effective Dose Equivalent, NUREG/CR-5512. Prepared by Pacific Northwest Laboratory for the'U.S. Nuclear Regulatory Commission, WaWagton, D.C., 1992. Lankford, W.T., et al. (editors),1985. The Afaking, Shaping and Treating ofSteel,10th Edition. , United States Steel and Association ofIron and Steel Engineers, Pittsburgh, Pennsylvania, 4 1985. Layton, D W.,1993. " Metabolically Consistent Breathing Rates for Use in Dose Assessments." i Health Physics, Volume 64, No.1, pp. 23-36. January 1993. l Logan, S.E.,1993. " Risk Assessment of Options for Disposition of EAF Dust Following a Meltdown Incident of Radioactive Cesium Source in Scrap Steel," SELA-9301. S. E. Logan and Associates, Inc., Santa Fe, New Mexico, April 1993. Maheras, S.J., A.S. Rood, S.O. Magnuson, M.E. Sussman, and R.N. Bhatt,1994. Radioactive Waste Afanagement Complex Low-Level Waste Radiological Performance Assessment. EGG-WM-8773. EGG Idaho, Idaho Falls, Idaho,1994. Draft NUREG 1640, Vol. I 9-6 O 1
Section 9 References Meck, R.A.,1992. U.S. Nuclear Regulatory Commission letter to Dr. Gordon Linsley, Scientific i Secretary, Division of Nuclear Fuel Cycle and Waste Management, International Atomic Energy Agency, November 9,1992. Microsoft,1997. Aficrosoft Excel 97 SR-1. Microsoft Corporation, Redland, Washington,1997. Miller, C.W. (ed.),1984. Afodels and Parametersfor Environmental Radiological Assessments, DOEfflC-11468. U.S.. Department of Energy, Washington, D.C., 1984. Mody, V., and R. Jakhete,1988. Dust Control Handbook, pp. 69-79. Martin Marietta Laboratories, Noyes Data Corporation, Park Ridge, New Jersey,1988. NCRP, I996. Guidefor Uncertainty Analysis in Dose and Risk Assessments Related to 1 Environmental Contamination, NCRP Commentary No.14. National Council on Radiation Protection and Measurements, Bethesda, Maryland, May 1996. NCRP,1984. Radiological Assessment: Predicting the Transport, Bioaccumulation, and Uptake by Afan ofRadionuclides Released to the Environment, NCRP Report No. 76. National Council on Radiation Protection and Measurements, Bethesda, Maryland, March 1984. Negin, C.A., and G. Worku,1992a. AficroShield, Version ./, User's Afanual, Grove 92-2. Grove Engineering, Inc., Rockville, Maryland, May 1992. s Negin, C.A., and G. Worku,1992b. RadDecay Radioactive Nuclide Lib.?ary and Decay Software Version 4. User's Manual, Grove 91-1. Grove Engineering, Inc., Rockville, Maryland, April 1992. Neuhauser, K.S., and P.L. Kanipe,1989. RADTRAN 4 User Guide: Technical Afanual, SAND 89-2370. Sandia National Laboratories, Albuquerque, New Mexico,1989. NIOSH,1990. Pocket Guide to Chemical Hazards. National Institute for Occupational Safety ; and Health, Cincinnati, Ohio,1990. NRC,1994a. StaffAction Planfor an Enhanced Participatory Rulemakingfor Recycle / Reuse Criteria, SECY 94-221. U.S. Nuclear Regulatory Commission, Washington, D.C., August 19,1994. NRC,1994b. Working Draft Regulatcry Guide on Release Criteriafor Decommissioning: NRC Staff's Draftfor Comment, NUREG-1500. U.S. Nuclear Regulatory Commission, Washington, D.C., August 1994. (D V 9-7 Draft NUREG 1640, Vol. I c
I Refirmces Section 9 NRC,1977. Calculation ofAnnual Doses to Alanfrom Routine Releases ofReactor Effluentsfor the Purpose ofEvaluating Compliance with 10 CFR Part 50, Appendix 1, Regulatory Guide 1.109. U.S. ' Nuclear Regulatory Commissica, Washington, D.C., October 1977. Oak, H.D., G.M. Holter, W E. Kennedy, Jr., and G J. Konzek,1980. Technology. S::fety, and Costs ofDecommissioning a Reference Boiling Water Power Station: Comparison of Two Decommissioning Cost Estimates Developedfor the Same Commercial Nuclear Reactor Power Station, NUREG/CR-0672. Prepared by Pacific Northwest Laboratory fec the U.S. Nuclear Regulatory Commission, Washington, D.C.,1980. O'Donnell, F.R., S.J. Cotter, D.C. Kocher, E.L. Etnier, and A.P. Watson,1978. Potential Radiation Dose to Alanfrom Recycle ofAfetals Reclaimedfrom a Decommissioned Nuclear Power Plant, NUREG/CR-0134, ORNL/NUREG/TM-215. Prepared by Oak Ridge National Laboratory for the U.S. Nuclear Regulatory Commission, Washington, D.C., December 1978. Rathje, W.L.,1991. "Once and Future Landfills." National Geographic, May 1991. i Roseberry, A.M., and D.E. Burmaster,1992. "Lognormal Distributions for Water Intake by Children and Adults." Risk Analysis, Volume 12, No.1,1992. l Royster, G.W., Jr., and B.R. Fish,1964. " Techniques for Assessing ' Removable' Surface Contamination," in Surface Contamination, Proceedings ofa Symposium Held at Gatlinburg, Tennessee, June 196-1. Pergamon Press, Oxford,1967. SC&A,1995. Analysis ofthe Potential Recycling ofDepartment ofEnergy Radioactive Scrap l Afetal. Sandy Cohen & Associates, Inc., McLean, Virginia, August 14,1995. l Schneider, K J., and C.E. Jenkins,1977. Technology, Safety and Costs ofDecommissioning a Reference Nuclear Fuel Reprocessing Plant, NUREGICR-0278. Prepared by Battelle Pacific Northwest Laboratory for the U.S. Nuclear Regulatory Commission, Washington, D.C.,1977. l l Simon, S. L.,1998. " Soil Ingestion by Humans: A Review of History, Data, and Etiology with Application to Risk Assessment of Radioactively Contaminated Soil." Health Physics, Volume 74, No. 6, pp. 647,672, June 1998. Slade, D.H.,1968. Afeteorology and Atomic Energy. U.S. Atomic Energy Commission, ; Washington, D.C.,1968. ; Smith R.I., G.J. Knozek, and W.E. Kennedy, Jr.,1978. Technology, Safety, and Costs of Decommissioning a Reference Pressurized Water Power Station, NUREGICR-0130. O; Draft NUREG-It>40, Vol. I 9-3 ) I
Section 9 References Prepared by Battelle Pacific Northwest Laboratory for the U.S. Nuclear Regulatory l(,q ,J Commission, Washington, D.C.,1978. Smith, G.R.,1996. Recycling -hferous Afetal, Volume 1-1994. U.S. Bureau of Mines, Washington, D.C.,1996. Solomon, C.,1993. Afineral Yearbook,1992: Slas fron andSteel. U.S. Bureau of Mines, Washington, D.C., September 1993. Spangler, G.W., and C.A. Willis,1964. " Permissible Contamination Limits," Surface
. Contamination, Proceedings ofa Symposium Held at Gatlinburg, Tennessee, June 196.I.
Pergamon Press, Oxford,1967. 1 Stewart K.,1964. "The Resuspension of Particulate Material from Surfaces,"in Surface l Contamination, Proceedings ofa Symposium Held at Gatlinburg. Tennessee, June 1961. 1 Pergamon Press, Oxford,1967. Szabo, M.F., and R.W. Gerstle,1078. Operation and Afaintenance ofParticulate Control Devices on Selected Steel and Ferroc. loy Processes, EPA-600/2-78-037. Prepared by PEDCo. Environmental, Inc., for the U.S. Environmental Protection Agency, Industrial Environmental Research Lab, Research Triangle Park, North Carolina,1978.
/m i(*) Till, J.E., and H.R. Meyer,1983. Radiological Assessment: A Textbook on EnvironmentalDose Analysis, NUREG/CR-3332. Prepared by Oak Ridge National Laboratory for the U.S.
Nuclear Regulatory Commission, Washington, D.C.,1983. USBM,1997. Recyclinr-Nonferrous Afettis, Afinerals Yearbook. U.S. Bureau of Mines, Washington, D.C.,1997. l l USBM,1985. Afineral Facts and Problems, Bulletin 675. U.S. Bureau of Mines, Washington, D.C.,1985. USPHS,1992. Toxicological Profilefor Aluminum and Compounds. Prepared by Clement l International Corporation for the, Agency for Toxic Substances and Disease Registry, U.S. ! Public Health Service, Atlanta, Georgia, July 1992. l I USPHS,1990. Toxicological Profilefor Copper. Prepared by Syracuse Research Corporation for the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service, ( Atlanta, Georgia, December 1990.
. Venturini, J.L.,1970. " Operating Experience with a Large Baghouse in an Electric Arc Fumace Steelmaking Shop." Journal ofthe Air Pollution Control Association,' Volume 20, No.12, fm December 1970.
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References Section 9 Yu, C., C. Loureiro, J.J. Cheng, L.G. Jones, Y.Y. Wang, Y P. Chia, and E. Faillace,1993. Data Collection Handbook to Support Afodeling the Impacts ofRadioactive Afaterialin Soil, ANL/EAIS-8. Argonne National Laboratory, Argonne, Illinois, April 1993. O l
)
{ l l l Draft NUREG 1640, Vol. I 9 10 el l I j l i
r GLOSSARY OF TERMS ' b (* = terms that are defined specifically for this analysis; others use standard definitions) ) l average member ofthe criticalgroup: A hypothetical individual that represents the average (mean) member of the critical group in terms of potential dose. bias: The tendency for an estimate to deviate from an actual or real event. Bias may be the tendency for a model to over- or underpredict. (Till and Meyer 1983) i bremsstrahlung: Photons emitted from an atom as a result of an electron losing energy as it passes near the highly charged nucleus of a heavy element. byproduct: See co-products
- clearance: The release of sources of radioactive material from regulatory control. Clearance of items could result in reuse, recycle, or direct disposal of equipment or material.
- clearance level: The level of activity or activity concentration at which clearance occurs.
I
*clearedmaterial: Equipment or material that has been cleared from regulatory control.
confidence interval: The lower and upper end points of an interval from a distribution. For O) (_ example, the interval from the 5th-percentile value to the 95th-percentile value is a "90% confidence interval" because it contains 90% of the estimated values in the distribution ] (95% minus 5%). l conservative bias: Intentional bias toward overestimation. (Till and Meyer 1983) q co-products: In the context of refinery co-products, this term refers to the major products ; resulting from the ref' ming of scrap metal. These co-products (also referred to as l byproducts) are refined metal, slag, baghouse dust, and off-gas. criticalgroup: The group ofindividuals reasonably expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances (10CFR20.1003). In this analysis for clearance of equipment and material, there is a critical group for each radionuclide evaluated. In this analysis, the critical group for each radionuclide is the group ofindividuals described in the exposure scenario that results in the highest mean dose factor fcr that radionuclide.
- critical-group dosefactor: The point-estimate dose factor for the average member of the critical group. This is the mean (average) dose factor from the distribution of dose factors calculated for the critical group for each radionuclide. For each material analyzed, there O is a critical-group dose factor for each radionuclide.
O glossary-1 Draft NUREG-1640, Vol. I
Glossary l deep dose equivalent: (H 4), which applies to extemal whole-body exposure, is the dose i equivalent at a tissue depth of I cm (1000 mg/cm2 ). (10CFR20) l 1 l descriptive statistics: Simple statistical measures that characterize a distribution of values. These are also refered to as moments of a distribution. Common descriptive statistics ; include the mean, the variance, and the standard deviation. deterministic: A model whose output is predetermined by the mathematical form ofits l I equations and the selection of a single value for each input parameter. (NCRP 1984) dose equivalent (Hr): the product of the absorbed dose in tissue, quality factor, and all other l necessary modifying factors at the location ofinterest. The units of dose equivalent are l } the rem and sievert (Sv). (10CFR20) dosefactor: A radionuclide-specific, hypothetical, dose ce!culated for the average member of a critical group, normalized to a unit radionuclide concentration in cleared material (i.e., pSv/a per Bq/g). The point estimate for the dose factor is the mean of the distribution of j possible dose factors. effective dose equivalent (H t): the sum of the products of the dose equivalent to the organ or tissue (H,) and the weighting factors (W,) applicable to each of the body organs or tissues that are irradiated (Hs = W1H,7 (10CFR20) element-dependentparameter: Typically refers to a parameter whose value is specific to a 3 given element, and therefore may be different for every element. exposure scenario: The set of circumstances that define a potential situation that could result in an exposure to an individual or group ofindividual Exposure scenarios are used to model potential doses resulting from reuse, recycle and disposal of material.
*geometryfactor: The dose rate from an external sc"rce of radiation from a specific source and source-receptor relationship.
Latin Hypercube sampling: A sampling method t' or probabilistic uncertainty analysis that divides a probability distribution into intervals of equci probability. Compared with conventional Monte Carlo random sampling, Latin Hypercube sampling is more precise because the entire range of the distribution is sampled in a more even, consistent manner. Latin Hypercube sampling was used in this analysis. licensed material source material, special nuclear material, or byproduct material received, possessed, useo, transferred or disposed of under a general or specific license issued by the Commission. (10CFR20) O Draft NUREG-1640 glossary-2 l
f: ] l r l l Glossary i massloading: A factor that relates concentration of a constituent in soil to the concentration of that constituent in air.
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*materialflow model: A modei that describes the flow of material and associated radioactivity L during recycle.
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l mean: The arithmetic average of a population-i.e., the sum of all of the values in the ! I population divided by the number in the population. (see geometric mean) i l median: Strictly, a value in a distribution such that there is a 0 5 probability that the actual value ; of the variable is less than that value. In common usage, it is the value in a distribution j such that half of the values are bigger, and half of the values are smaller. ; i model: A mathematical abstraction of an ecological or biological system, sometimes including j specific numerical values for the parameters of the system. (NCRP 1984). l l 1 l parameter: Any one of a set of variables in a model wbme valu:s detuadue model predictions. (Ti!! ad Meyer 1983). i !
- partitioning: The differential movement of one material as compared to another material. For j this analysis, partitioning is used in the context of the steel refining process, specifically i during melting in a furnace.
mass partitioning: the redistribution of mass during melting in a refinery furnace. The mass of the material in a furnace is distributed to refined metal, slag, and dust ; i during the refimng process. 3 i elementpartitioning: the redistribution of chemical elements during melting in a refinery furnace. The elements in the material in a furnace are distributed to j refined metal, slag, dust, and offgas during the refining process depending on their chemical characteristics. j l percentilc: Strictly, a value in a distribution, expressed as a percentage, such that there is a given - L probability that any value in the distribution is less than that ,alue. Ia cammon usage, it ; ! is the value in a distribution such that the given fraction (percentage) of values are less j than that value. For example,95% of the values in a distribution are Icss than the i 95-percentile value. i
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probabilistic model A system whose input and output is expressed as a distribution of possible values. The output distribution results from uncertainty in the input parameters.
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j l O I l glossary 3 Draft NUREG-1640, Vol. I i l 1
Glossary probability distribution: A set of all possible values of a parameter, and their associated probability. The probability distributions used in this analysis are uniform, triangular, normal, and lognonnal. progeny: The nuclide resulting from the radioactive disintegration of a radionuclide, formed either directly or ca the result of successive transfonnations in a radioactive series. Progeny may be either radioactive or stable. radionuclide: An atom that, due to its atomic instability, undergoes spontaneous nuclear disintegration. Nuclear disintegration is accompanied by the emission of charged particles and/or photons, and results in the formation of another, distinct atom (see progeny). radion uclide-dependent purameter: A parameter whose value is specific 'o a given radionuclide, and therefore may be different for every radionuclide. radionacilae-independentparameter: A parameter whose value is not specific to a given radionuclide, and therefore is the same for every radionuclide, realistic: Typical of a real-life situation, and therefore likely to be observed in real life. An accurate representation of a reasonably foreseeable real-life situation.
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- recycle: Conversion of materials (i.e., steel. copper, aluminum, concrete) present in components from a nuclear facility to form new products through normal industrial processes, which wculd then be aveilable in the public sector.
- refining: In the context of clearance of equipment and material, refining means melting in a furnace at a metals refinery. Refining results in the production of the co-products refined metal, slag, baghouse dust, and off-gas.
- reuse: Transfer of a functional component or material from a nuclear facility without any processing, to some other application where it would be used to carry out its original function.
saturated zone: That portion of porous ground media in which the interconnecting interstices are filled with water. (Till and Meyer 1983)
- scrap material: manufactured items or part.s that are no longer useful for their original purpose that have value as material for reprocessing.
secondary ingestion: accidental or unintentional ingestion of material (also sometimes referred to as " inadvertent ingestion)." In this analysis, secondary ingestion applies to the unintentional ingestion of soil and dust. Draft NUREG-1640 glossary-4 ! l
f l l 9 \ j Glossary I -l l 'sen.5itivity: The mathematical sensitivity of the model predictions to selected perturbations of
.( model parameters. (NCRP 1984)
I sensitivity analysis:- Identification of the relative contrib6 tion of the uncertainty in a given model component to the total uncertainty in the model result. (NCRP 1996) i spreadsheet: A calculational computer software application. total effective dose equivalent (TEDE): the sum of the deep-dose equivalent (for extemal L exposures) and the committed effective dose equivalent (for internal exposures). (10CFR20): i uncertainty: The lack of sureness or confideiice in the predictions of models. (NCRP 1984) i i uncertainty analysis: The computation of the total uncertainty induced in the output by quantified uncertainty in the inputs and models, and the attributes of the relative importance of the input uncertainties in terms of their contributions. (NCRP 1996) l ' L uniform distribution: A distribution of values such that all values are equally likely to occur, or i altcmatively, eqtially likely to be sampled during conduct of an uncertainty analysis. j unsaturated zone: The portion of porous media in the ground where the intercconecting l interstices are only partially filled with fluid. (NCRP 1984) J i glossary-5 Draft NUREG-1640, Vol.1
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