ML12278A373

Buffalo Materials Research Center Final Status Survey Plan, Revision 1

ML12278A373
Person / Time
Site:	University of Buffalo
Issue date:	09/20/2012
From:	Brautigam T Enercon Services
To:	NRC/FSME, University of Buffalo
References
Download: ML12278A373 (13)

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Final Status Survey Plan Buffalo Materials Research Center Prepared for:

Buffalo Material Research Center Office of Environment, Health, and Safety Services Completed by:

4490 Old William Penn Hwy Murrysville, PA 15668 Revision 1 September 20, 2012

BMRC Final Status Survey Plan Revision 1

SUMMARY

OF CHANGES Revisions to the Final Status Survey Plan will be tracked when revisions are issued. Changed sections will be identified by special demarcation in the margin. A summary description of each revision will be noted in the following table.

Revision Date Description of Change Number 0 June 20, 2012 Initial Issue Pages ii-vi: Updated Table of Contents, Tables, and Abbreviations/Acronyms.

Page 15: Added reference to BMRC FSS standard deviation calculation method in Section 3.5.5.

1 September 20, 2012 Pages 18-22: Reorganized and clarified Section 3.6 regarding instruments and detection limits. Added gamma walkover instrumentation to section.

Page 23: Clarified selection of LBGR and corrected the number of required data points for a relative shift of 1.5.

Prepared By: Date: 9/20/2012 Todd Brautigam Technical Specialist Reviewed By: Date: 9/20/2012 Frank Brown Technical Specialist Approved By: Date: 9/20/2012 Dustin G. Miller, CHP DOC Project Manager ii

BMRC Final Status Survey Plan Revision 1 TABLE OF CONTENTS 1.0 INTRODUCTION .......................................................................................................................... 1

1.1 Purpose ................................................................................................................................... 1

1.2 Scope ...................................................................................................................................... 1

2.0 SITE DESCRIPTION .................................................................................................................... 2

2.1 Facility and Reactor Description ............................................................................................ 2

2.2 Radionuclides of Concern ...................................................................................................... 7

3.0 FINAL STATUS SURVEY PROCESS ........................................................................................ 8

3.1 Overview ................................................................................................................................ 8

3.2 Release Criteria ...................................................................................................................... 9

3.3 Surveys and Sampling .......................................................................................................... 11

3.4 Measurement and Sample Locations .................................................................................... 13

3.5 MARSSIM Statistical Parameters ........................................................................................ 14

3.6 Instruments and Detection Limits ........................................................................................ 18

3.7 Daily Instrument and Background Measurements ............................................................... 22

3.8 Reference Area Measurements ............................................................................................. 22

3.9 Projected Survey Units ......................................................................................................... 22

3.10 Volumetric Sample Collection ............................................................................................. 26

3.11 Investigation Levels and Elevated Areas Test ..................................................................... 26

4.0 DATA QUALITY OBJECTIVES............................................................................................... 32

5.0 FSS REPORT ............................................................................................................................... 33

6.0 QUALITY ASSURANCE ............................................................................................................ 34

6.1 Training and Qualification ................................................................................................... 34

6.2 Measurement/Data Acquisition ............................................................................................ 34

6.3 Volumetric Analyses ............................................................................................................ 35

6.4 Instrument Selection, Calibration and Operation ................................................................. 35

6.5 Data Management ................................................................................................................ 36

6.6 Data Validation .................................................................................................................... 36

6.7 Confirmatory Measurements ................................................................................................ 36

7.0 REFERENCES ............................................................................................................................. 37

8.0 ATTACHMENTS ........................................................................................................................ 38

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BMRC Final Status Survey Plan Revision 1 FIGURES Figure 2-1: University of Buffalo South Campus ......................................................................................... 2

Figure 2-2: Control Deck Layout .................................................................................................................. 4

Figure 2-3: Gamma Deck Layout.................................................................................................................. 5

Figure 2-4: Neutron Deck Layout ................................................................................................................. 6

Figure 3-1: Anticipated Survey Units ......................................................................................................... 13

TABLES Table 2-1 BMRC Radionuclides of Concern ................................................................................................ 7

Table 3-1: DCGLs for Primary Radionuclides of Concern in Soil ............................................................. 10

Table 3-2: NRC License Termination Screening Levels for Building (Bedrock) Surfaces ........................ 10

Table 3-3: MARSSIM Table 5.1 ................................................................................................................. 17

Table 3-4: MARSSIM Table 5.4 ................................................................................................................. 18

Table 3-5: FSS Instrumentation .................................................................................................................. 19

Table 3-7: Survey Units .............................................................................................................................. 23

Table 3-8: N16 Tank Area Characterization Results Summary .................................................................. 23

Table 3-9: Class 2 Soil Characterization Results Summary ........................................................................ 25

Table 3-10: Analysis Methods for Volumetric Samples ............................................................................. 26

Table 3-11: Measurement Result Investigation Levels ............................................................................... 27

Table 3-12: DCGLemc Values .................................................................................................................... 29

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BMRC Final Status Survey Plan Revision 1 ABBREVIATIONS/ACRONYMS R/hr microRoentgen per hour 2x2 NaI 2-inch by 2-inch sodium iodide detector AEC Atomic Energy Commission BMRC Buffalo Materials Research Center Bq Bequerels 2

cm Centimeter Squared cpm counts per minute CFR Code of Federal Regulations D&D Decontamination and Decommissionoing DCGL Derived Concentration Guideline Level DCGLemc Derived Concentration Guideline Level Elevated Measurement Comparison DOC Design and Oversight Contractor DP Decommissioning Plan DQO Data Quality Objective DPM or dpm disintegrations per minute FSS Final Status Survey FSSP Final Status Survey Plan kw kilowatt LBGR Lower Bound of the Gray Region m meter 2

m Meters square MARSSIM Multi-Agency Radiation Site Survey and Investigation Manual, NUREG-1575 MDA Minimum Detectable Activity MDC Minimum Detectable Concentration MDCR Minimum Detectable Count Rate MDCscan Minimum Detectable Concentration for scans mrem Millirem NaI Sodium Iodide NELAP National Environmental Laboratory Accreditation Program NVLAP National Voluntary Laboratory Accreditation Program MWt Megawatt thermal NIST National Institute of Standards and Technology NRC U.S. Nuclear Regulatory Commission ORISE Oak Ridge Institute for Science and Education v

BMRC Final Status Survey Plan Revision 1 pCi/g Picocuries per gram PULSTAR Pulse Training Assembled Reactor QA/QC Quality Assurance/Quality Control SSC Systems/Structures/Components University State University of New York at Buffalo VSP Visual Sample Plan © WRS Wilcoxon Rank Sum Radionuclide Abbreviations Ag Silver C Carbon Co Co-60 Cs Cesium H Hydrogen Pu Plutonium Sr Strontium Th Thorium ZnS Zinc Sulfide vi

BMRC Final Status Survey Plan Revision 1 If the contaminant is not in the background or constitutes a small fraction of the DCGL, the Sign Test will be used. If background is a significant fraction of the DCGL, the WRS Test will be used. It is anticipated that the Sign Test will be the only statistical test applied to the collected data because of the small fraction of the DCGL that background radionuclides will contribute.

3.5.2 Establish Decision Errors The probability of making decision errors is controlled by hypothesis testing. The survey results will be used to select between one condition of the environment (the null hypothesis) and an alternate condition (the alternative hypothesis). These hypotheses, chosen from MARSSIM Scenario A, are defined as follows:

x Null Hypothesis (H0): The survey unit does not meet the release criteria.

x Alternate Hypothesis (Ha): The survey unit does meet the release criteria.

A Type I decision error would result in the release of a survey unit containing residual radioactivity above the release criteria. It occurs when the Null Hypothesis is rejected, but in reality is true. The probability of making this error is designated as D.

A Type II decision error would result in the failure to release a survey unit when the residual radioactivity is below the release criteria. This occurs when the Null Hypothesis is accepted when it is not true. The probability of making this error is designated as E.

Appendix E of NUREG-1727 recommends using a Type I error probability (D) of 0.05 and states that any value for the Type II error probability (E) is acceptable. Following the guidance, D will be set at 0.05. A E of 0.05 will initially be selected based on site-specific considerations. The E may be modified, as necessary, after weighing the resulting change in the number of required survey measurements against the risk of unnecessarily investigating and/or remediating survey units that are truly below the release criteria.

3.5.3 Relative Shift The relative shift (/) is a calculated value. Delta () is equal to the DCGL minus the lower boundary of the gray region (LBGR). The standard deviation () used for the relative shift calculation may be recalculated based on the most current data obtained from post-remediation or post-demolition surveys; or from background reference areas, as appropriate. See Section 3.5.5 for the specific method of calculating the standard deviation for the BMRC FSS. The LBGR may be adjusted to obtain an optimal 15

BMRC Final Status Survey Plan Revision 1 Table 3-4: MARSSIM Table 5.4 Relative Sign p Relative Shift Sign p Shift 0.1 0.539828 1.2 0.88493 0.2 0.57926 1.3 0.903199 0.3 0.617911 1.4 0.919243 0.4 0.655422 1.5 0.933193 0.5 0.691462 1.6 0.945201 0.6 0.725747 1.7 0.955435 0.7 0.758036 1.8 0.96407 0.8 0.788145 1.9 0.971284 0.9 0.81594 2 0.97725 1 0.841345 2.5 0.99379 1.1 0.864334 3 0.99865 Note: If relative shift > 3.0, use Sign p = 1.0 3.6 Instruments and Detection Limits 3.6.1 Survey Instruments The FSS will consist of walkover surveys with gamma scintillation detectors, and soil sampling with off-site analysis, scans and direct measurements with floor monitors. The instruments proposed for use during the FSS and their applications are provided in Table 3-5 . If necessary, the DOC may substitute comparable instruments.

All instruments will be calibrated using NIST-traceable standards. Instruments will be checked at the beginning of each day to ensure they are operating properly. The daily check also reassures the validity of the previous day's measurements. The daily checks will include a background measurement and a source check. Instrument records, including dates of use, efficiencies, calibration due dates and source traceability, will be maintained in accordance with established procedures.

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BMRC Final Status Survey Plan Revision 1 Table 3-5: FSS Instrumentation Radiation Calibration Instrument Detector Type Use Detected Source Ludlum Model 44-10 Ludlum Model 2221 Gamma Cs-137 Gamma Walkover Surveys 2 x 2 NaI Surface Static Ludlum Model 43-68 Gas Ludlum Model 2221 Beta Tc-99 Measurements; Beta scan Proportional (126 cm2) measurements Ludlum Model 43-68 Gas Alpha/Beta static Ludlum Model 2360 Alpha/Beta Th-230/Tc-99 Proportional (126 cm2) measurements Ludlum Model 43-89 ZnS Alpha/Beta static Ludlum Model 2360 coated Plastic Scintillator Alpha/Beta Th-230/Tc-99 measurements (126 cm2)

Ludlum Model 43-10-1 Ludlum Model 3030E Alpha/Beta Th-230/Tc-99 Swipe/smear counting ZnS internal detector General area exposure Ludlum Model 19 Internal NaI Gamma Cs-137 rates 3.6.2 Minimum Detectable Concentration The minimum detectable concentration (MDC) is the concentration of radioactivity that an instrument can be expected to detect at a 95 percent confidence level. For instruments performing direct measurements and for laboratory analyses, the MDC goal is 10-50 percent of applicable release criteria.

For static (direct) surface measurements, with conventional detectors, the MDC was calculated using the formula:

3  3.29 Rb Ts 1  Ts / Tb º MDC (dpm/100cm2) = << >>

<<¬ Ts Ht >>1/4 Where:

Rb = Background count rate (cpm)

Tb = Background count time (min)

Td = Sample Run Time (min)

Ts = Sample Count Time (min)

Ht = Total Instrument Efficiency (MARSSIM section 6.6.1)

The data used to calculate the MDC for the instrumentation is from data collected during the BMRC characterization process. The a priori MDC is listed in Table 3-6.

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BMRC Final Status Survey Plan Revision 1 For gamma scan measurements in the gamma walkover survey, the minimum detectable count rate (MDCR) is calculated as the survey is used as a qualitative analysis for elevated concentrations also known as hot spots. The MDCR is calculated by first determining the minimum detectable net source counts using Formula 6-8 from the MARSSIM as below.

si d c bi Minimum number of detectable source counts:

Where:

d = value taken from Table 6.5 in the MARSSIM for applicable true and false positive rates bi = Number of background counts in a given time interval The MDCR is calculated from Formula 6-9 in the MARSSIM:

60 MDCR si

• Minimum detectable count rate: i Where:

i = Observed time interval For beta scan measurements, the MDCR equation is used along with the detection efficiency and probe area correction factor to calculate the MDC for a beta scan measurement (MDCscan) in standardized units (DPM/100-cm2). The MDCscan formula is the following:

MDCR MDC scan probearea U *Hi *Hs

• Scan MDC: 100cm 2 Where:

= Surveyor efficiency (value from a range between 0.5 and 0.75) i = Instrument efficiency s = Surface efficiency probearea = active area of the detector face in cm2 The value for was developed in Draft NUREG/CR-6364 and NUREG-1507, it is a percentage estimate of the likelihood a surveyor will reliably detect an elevated count rate. A value of 0.5 will be used for the Surveyor Efficiency.

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BMRC Final Status Survey Plan Revision 1 Table 3-6: Instrumentation MDC Radiation Typical Scan Typical Static Instrument Detector Type MDC MDC Detected (dpm/100 cm2) (dpm/100 cm2)

Ludlum Model 2221 Ludlum Model 44-10 Gamma See Section 3.6.3 N/A Ludlum Model 2221 Ludlum Model 43-68 Beta 1736 271 Alpha N/A 59 Ludlum Model 2360 Ludlum Model 43-68 Beta 2981 393 Alpha N/A 47 Ludlum Model 2360 Ludlum Model 43-89 Beta 4292 612 Alpha N/A 12 Ludlum Model 3030E Ludlum Model 43-10-1 Beta N/A 159 Ludlum Model 19 Internal NaI Gamma N/A N/A 3.6.3 Verification of Gamma Walkover Detection Limits for Ag-108m Based on data presented in NUREG-1507 (Reference 7.6), the MDCscan for a walkover survey with a 2x2 NaI detector is approximately 3.4 pCi/g and 6.4 pCi/g for Co-60 and Cs-137, respectively as shown in Table 6.4 of NUREG-1507 . There is no data listed for Ag-108m. However, based on the gamma photon energies of Ag-108m, the walk-over surveys should be capable of identifying the presence of residual contamination at levels below the DCGLs.

To verify that Ag-108m would be appropriately detected, the expected exposure rates for Co-60 and Ag-108m at their respective DCGLs were individually calculated using Microshield© with an infinite slab source geometry. Then by applying the instrument detection specifications for counts per minute (cpm) per R/hr, the expected count rate at the DCGL was calculated.

The analysis for Co-60, presented in Attachment 8.1, shows that the expected exposure rate for soil containing 3.8 pCi/g Co-60 would be 11 R/hr. Using the conversion factor of 430 counts per minute (cpm) per R/hr from Reference 7.6, the required minimum detectable count rate (MDCR) to measure 3.8 pCi/g of Co-60 would be approximately 4,730 cpm.

Microshield was used in the same way to model Ag-108m. This analysis, presented in Attachment 8.2, shows that the expected exposure rate for soil containing 8.2 pCi/g Ag-108m would be 20.9 R/hr. Based off the Microshield evaluation, the average weighted energy of Ag-108m is ~50 keV. The detection sensitivity for a 2x2 NaI detector at that energy range is approximately 3,600 cpm per R/hr (Reference 21

BMRC Final Status Survey Plan Revision 1 7.7), therefore the required MDCR to measure 8.2 pCi/g of Ag-108m would be approximately 75,200 cpm.

Using the MDCR equation in Section 3.6.2 and estimating a background count rate of 8,000 cpm the expected MDCR is 1,352 net cpm (841 cpm less than the required MDCR) or approximately 9,350 gross cpm (depending on the true background rate on site). Using the MDCscan (pCi/g) equation above, this MDCR correlates to an expected MDCscan of about 3.1 pCi/g for Co-60 contamination in the soil.

3.7 Daily Instrument and Background Measurements Daily instrument checks will be made according to written procedures. These measurements will be made in non-impacted areas using radioactive check sources. These measurements will be recorded for the purpose of ensuring that instruments are operating properly. An instrument control log will be used for each instrument to keep track of background counts and response checks.

Daily background measurements will also be made according to written procedures. These measurements will be made in non-impacted areas. Single background measurements used to estimate the mean background will be made for a minimum of 10 minutes for scaling instruments (scalers).

3.8 Reference Area Measurements The radionuclides of concern at the BMRC fall into two distinct categories:

1) The DCGL is low and the radioisotope is generally not detectable in background samples (cobalt, silver, and europium), and

2) The DCGL is high compared to the expected background concentration (remaining isotopes)

Therefore, to simplify matters, the site release statistical tests will assume that none of the radioisotopes of concern are present in background. Based on this assumption, MARSSIM recommends the Sign Test for statistical comparisons. No reference area measurements are required for the Sign Test to release the site based on the soil sample results.

3.9 Projected Survey Units The projected survey units and associated classes are shown in Table 3-7. The selected LBGR for each survey unit is based on empirical characterization data using the average of the characterization sample results that were reported as less than the radionuclide specific DCGL. Sample results greater than the radionuclide specific DCGL were not used in this calculation since remediation should occur in the 22

BMRC Final Status Survey Plan Revision 1 immediate area of the sample. Using this method, the selected LBGRs are representative of the anticipated post-remediation radiological conditions.

Table 3-7: Survey Units Area Relative Required Survey Unit Unit # Class (m2) Shift Data Points N16 1 1 90 1.5 18 Tank Farm 2 1 105 1 29 Sub-Basement 3 1 300 1 29 Containment 4 1 420 1 29 Side slopes 5 2 1,230 3.0 14 Cooling Tower 6 2 105 1 29 Remainder 7 3 >2,000 3.0 14 3.9.1 Class 1 Survey Units 3.9.1.1 N16 Tank Area - Survey Unit 1 The N16 tank is known to have radioactivity greater than NRC and NYS Screening values for Co-60.

Additionally, Ag-108m was elevated and has a high potential to be greater than the release criteria (Reference 7.5). The N16 tank area encompasses approximately 90 m2.

A summary of the characterization data for the detected radionuclides of interest for this area is shown in the table below. This data summary excludes sample results greater than the relevant DCGL in order to properly calculate the relative shift.

Table 3-8: N16 Tank Area Characterization Results Summary Standard DCGL Calculated Radionuclide LBGR Deviation (pCi/g) Relative Shift Ag-108m 4.9 2.2 8.2 1.5 Co-60 2.54 0.84 3.8 15 Cs-137 1.86 1.75 11 5.2 Eu-152 0.54 0.86 6.9 7.3 Eu-154 0.34 0.37 8 20.7 H-3 4.8 2.4 110 43.8 Ni-63 33.7 25.1 2,100 82.3 Sr-90 0.14 0.13 1.7 12 The lowest relative shift calculated from this data is 1.5 which correlates to a minimum of 18 samples to meet MARSSIM data requirements.

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