ML12100A124
| ML12100A124 | |
| Person / Time | |
|---|---|
| Site: | Plum Brook File:National Aeronautics and Space Administration icon.png |
| Issue date: | 04/03/2012 |
| From: | Mann B US National Aeronautics & Space Admin (NASA), John H. Glenn Research Ctr at Lewis Field |
| To: | NRC/FSME |
| References | |
| Download: ML12100A124 (78) | |
Text
Plum Brook Reactor Facility Final Status Survey Report Revision 1 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations
FINAL STATUS SURVEY REPORT ROUTING AND APPROVAL SHEET Document
Title:
Final Status Survey Report, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Revision Number: I ROUTING SIGNATURE DATE Prepared By B. Mann
,'(W Prepared By N/A REVIEW & CONCURRENCE Independent Technical Reviewer R. Case M 73 Other Reviewer, QA Manager J. Thomasr Other Reviewer N/A FSS/Characterization Manager W. Stoner NASA Project Radiation Safety Officer W. Stoner ii
NASA PBRF DECOMMISSIONING PROJECT CHANGE/CANCELLATION RECORD DOCUMENT TITLE:
Final Status DOCUMENT NO: NA REVISION NO: 1 Survey Report, Attachment 7, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Revision 0: Initial issue of Report Revision 1: A new Figure (Figure 1, page 7) was inserted to show locations of site spill areas. The previous Figure 1 was renumbered to read "Figure 2". Text was revised to reflect these changes. This change is in response to an NRC comment/question requesting that a figure be added to show the location of the discrete spill areas described in Table 1.
D-1/3 Rev I iii
Plum Brook Reactor Facility FSSR, Rev. 1 LIST OF EFFECTIVE PAGES DOCUMENT NO:
NA REVISION NO: 1 Page No.
Revision Level Page No.
Revision Level Page No.
Revision Level Cover Page 1
Routing & Approval 1
.Sheet Change/Cancellation 1
Record LOEP TOC List of Tables & List 1
of Figures List of Acronyms &
Symbols, 3 pages Text, pages 1 through 5
Text, pages 6 through 1
47 Appendix A 22 pages Appendix B 41 pages Appendix C 17 pages AD-01/5 Rev 2 iv
Plum Brook Reactor Facility FSSR, Rev. 1 TABLE OF CONTENTS 1.0 Introd uction....................................................................................................................
1 2.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Description........ 2 2.1 H istory of Site Operations.......................................................................................
3 2.2 Site Geology and Soil Description...........................................................................
4 2.3 Site Soil Characterization.................................................................................
........ 5 2.4 Storm Drain System Operation...............................................................................
8 2.5 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Construction......... 11 2.6 Final Configuration and Scope of Remediation of SDPTSSE for Final Status Survey 13 2.6.1 Storm Drain System Dismantlement.................................................................
13 2.6.2 Cold Retention Basin Dismantlement.....................................................................
16 2.6.3 Impacted Utility Excavations..............................................................................
16 2.6.4 Spill A rea Excavation.........................................................................................
17 2.6.5 Removal of Storm Sewer South of SEB (RCRA Area Excavation)...................
18 3.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations History and Operations with Radioactive Materials...........................................................................
19 3.1 Disposition of Materials in the Post-Shutdown Period.........................................
20 3.2 D ecom m issioning...................................................................................................
21 4.0 Survey Design and Implementation for Storm Drains, Pipe Trenches & Other Sub-Surface Excavations...................................................................................................
22 4.1 FSS Plan Requirements.........................................................................................
22 4.1.1 Site-Specific DCGL Values for Soil..................................................................
23 4.1.2 DCGL for Other Media.......................................................................................
23 4.1.3 Radionuclide Mixture for FSS...........................................................................
23 4.1.4 Surrogate DCGL and the Unity Rule..................................................................
24 4.1.4.1 Surrogate Equation.........................................................................................
25 4.1.4.2 Unity Rule Equation.......................................................................................
26 4.1.4.3 A rea Factors..................................................................................................
26 4.1.4.4 Survey U nit Size..............................................................................................
27 4.1.4.5 Scan Coverage for Class 1 Areas....................................................................
27 4.2 Area Classification and Survey Unit Breakdown.................................................
28 4.2 Number of Measurements and Samples.................................................................
30 4.3 Instrumentation and Measurement Sensitivity......................................................
33 5.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Survey Results 35 5.1 Surveys and Investigations....................................................................................
35 5.1.1 Scan S urv eys........................................................................................................
35 5.1.2 Investigative Measurements and Judgmental Soil Samples...............................
37 5.1.3 Systematic Soil Sampling...............................................................................
40 5.1.3.1 Soil Sampling for Class 1 Areas...........................................................................
40 5.1.3.2 Quality Control Sample Analysis....................................................................
41 5.2 A LA RA Evaluation...
44 5.3 Comparison with EPA Trigger Levels.................................................................
44 5.4 C onclusions................................................................................................
............ 45 6.0 R eferences.....................................................................................................................
46 7.0 A p pend ices....................................................................................................................
47 V
Plum Brook Reactor Facility FSSR, Rev. 1 Appendix A - Exhibits Appendix B - Survey Unit Maps and Tables Showing Measurement Locations Appendix C - Final Status Survey Soil Sample Results LIST OF TABLES Table 1, Spill A rea Sum m ary....................................................................................................
6 Table 2, Principal Radionuclides and Activity Fractions for Site Soils.....................................
8 Table 3, DCGL Values for Surface Soil..................................................................................
23 Table 4, Surrogate DCGLs for Soil FSS..................................................................................
25 Table 5, Surface Soil A rea Factors...........................................................................................
27 Table 6, Recommended Survey Unit Area Size Requirements for FSS...................................
27 Table 7, Minimum Scan Survey Coverage.............................................................................
27 Table 8, Storm Drains, Pipe Trenches and Sub-Surface Excavations Survey Unit Classification C om parison to FS SP.....................................................................................................................
28 Table 9, Storm Drains, Pipe Trenches and Other Sub-Surface Excavations Survey Unit Breakdown by MARSSIM Classification................................................................................
30 Table 10, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Survey Design Sum m ary.......................................................................................................................................
3 1 Table 11, Sensitivity Analysis for OL-1-26 Design.................................................................
32 Table 12, Typical Detection Sensitivities of 44-10 for Co-60 and Cs-137.............................
34 Table 13, Scan Survey R esults.................................................................................................
36 Table 14, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Systematic Soil Sam ple Results By Survey U nit..............................................................................................
42 LIST OF FIGURES Figure 1, PBRF Site Map Showing Spill Areas.........................................................................
7 Figure 2, Storm Drains, Pipe Trenches & Other Sub-Surface Excavation and Survey Unit L ocation M ap...........................................................................
19 vi
Plum Brook Reactor Facility FSSR, Rev. 0 LIST OF ACRONYMS & SYMBOLS cx A
bi BPL CB CFR CRB cm CMP cpm A
d' DCGL DCGLEMC DCGLw DL dpm dpm/100 cm 2 EMC ERB EPA FH FPR FSS FSSP FSSR ft.
g HL HTD HRA iIM alpha; denotes alpha radiation, also type I error probability in hypothesis testing Area, also detector open area Area corresponding to the area factor calculated using the scan MDC Atomic Energy Commission Area of Concern As Low As Reasonable Achievable Assembly, Test and Storage Building beta; denotes beta radiation, also type II error probability in hypothesis testing background counts in observation interval Byproduct License Catch Basin Code of Federal Regulations Cold Retention Basin centimeters Corrugated Metal Pipe counts per Minute delta, DCGLw - LGBR Scan surveyor sensitivity index Derived Concentration Guideline Level DCGL for small areas of elevated activity, used with the Elevated Measurement Comparison test (EMC)
DCGL for average concentrations over a survey unit, used with statistical tests. (the "W" suffix denotes "Wilcoxon)"
Drain Line disintegrations per minute disintegrations per minute per 100 centimeters squared Elevated Measurement Comparison Emergency Retention Basin US Environmental Protection Agency Fan House Building Final Post Remediation Final Status Survey Final Status Survey Plan Final Status Survey Report feet gamma, denotes gamma radiation gram Hot Lab Hard To Detect Hot Retention Area observation counting interval during scan surveys Investigative Measurement vii
in.
LBGR m2 MARSSIM MDC MDCscan MDCstatic MDCR MOU mrem MW MWH NASA N
NA Nal ncpm NRC OL PBOW PBRF PNL PPH QC p
pCi/g QC RCP RCRA RESRAD ROLB ROB RSCB s
a S+
SDPTSSE SDS SEB Plum Brook Reactor Facility FSSR, Rev. 0 LIST OF ACRONYMS & SYMBOLS, Continued inch Lower Bound of the Gray Region square meters Multi-Agency Radiation Survey and Site Investigation Manual Minimum Detectable Concentration Minimum Detectable Concentration for scanning surveys Minimum Detectable Concentration for static surface activity measurements Minimum Detectable Count Rate Memorandum of Understanding millirem Megawatt Mongomery Watson Harza National Aeronautics and Space Administration Number of FSS measurements or samples established in a survey design Not Applicable Sodium Iodide net counts per minute US Nuclear Regulatory Commission Open Land Plum Brook Ordinance Works Plum Brook Reactor Facility Pacific Northwest Laboratory Primary Pump House Quality Control Standard normal distribution function surveyor efficiency for scan surveys picocuries per gram percent Quality Control Rigid Corrugated Pipe Resource Conservation and Recovery Act RESidual RADioactive - a pathway analysis computer code developed by Argonne National Laboratory for assessment of radiation doses. It is used to derive cleanup guideline values for soils contaminated with radioactive materials Reactor Office and Laboratory Building Reactor Office Building Reactor Security and Control Building seconds generic symbol for standard deviation of a population Sign Test statistic Storm Drains, Pipe Trenches and Other Sub-Surface Excavations Storm Drainage System Services Equipment Building viii
Plum Brook Reactor Facility FSSR, Rev. 0 LIST OF ACRONYMS & SYMBOLS. Continued SNL Sandia National. Laboratory SR Survey Request STS Storm System SSS Sanitary Sewer System TBD Technical Basis Document P
Mean activity concentration VSP Visual Sample Plan WEMS Waste Effluent Monitoring Station WEP Work Execution Plan WHB Waste Handling Building ZIla Proportion of standard normal distribution values less than 1 -a ZI-0 Proportion of standard normal distribution values less than 1-I 00 Mathematical symbol for infinity ix
Plum Brook Reactor Facility FSSR, Rev. 0 1.0 Introduction This report presents the results of the final status radiological survey of the Plum Brook Reactor Facility (PBRF) Storm Drains, Pipe Trenches and Other Sub-Surface Excavations (SDPTSSE). It is Attachment 7 of the PBRF Final Status Survey Report (FSSR) 1. This attachment describes the operational history and final condition for the final status survey (FSS) of the Storm Drains, Pipe Trenches and Sub-Surface Excavations covered by this document. It describes the methods used in the FSS and presents the results of the survey measurements.
As stated in the PBRF Final Status Survey Plan (FSSP) [NASA 2007], the goal of the decommissioning project is to release the facility for unrestricted use in compliance with the criteria in US NRC 10CFR20 Subpart E. The principal criterion is that the dose to future site occupants will be less than 25 mrem/year. Subpart E also requires that residual contamination be reduced to levels as low as reasonably achievable (ALARA). A Derived Concentration Guideline Level (DCGL) for surface and sub-surface soils has been established for PBRF soils, per Table 3-1 of the FSSP and in Table 2-2 of the Technical Basis Document (TBD)
PBRF-TBD-09-001[PBRF 2009]. In accordance with the FSSP and TBD-09-001, the primary DCGLs for surface soil are as follows:
- Co-60 is 3.8 pCi/g,
- Sr-90 is 5.4 pCi/g, and
- Cs-137 is 14.7pCi/g.
Furthermore, surrogate DCGLs for soil of the SDPTSSE were established in Table 5-2 of PBRF-TBD-09-001 and are provided in Table 2 of this report.
The survey measurement results and supporting information presented herein demonstrate that residual contamination levels in each survey unit of the SDPTSSE are well below the DCGL. Additionally, it is shown that residual contamination has been reduced to levels that are consistent with the ALARA requirement. Therefore, the SDPTSSE meets the criteria for unrestricted release.
Section 2.0 of the report provides a description of the SDPTSSE. This section also discusses the final configuration of the SDPTSSE for the FSS and scope of the FSS for this area.
A brief history of operations is presented in Section 3.0. A chronology of significant milestones is followed by history of operations with radioactive materials. Post shutdown and decommissioning activities are summarized.
Section 4.0 presents the FSS for the SDPTSSE. This section includes FSS Plan requirements applicable to the SDPTSSE, breakdown into survey units and assignment of MARSSIM The PBRF Final Status Survey Report comprises the report main body and several attachments. The attachments present survey results for individual buildings and open land areas. The entire final report will provide the basis for requesting termination of NRC Licenses TR-3 and R-93 in accordance with 10CFR50.82 (b) (6).
1
Plum Brook Reactor Facility FSSR, Rev. 0 classification to each, the survey design approach, and instrumentation used for the FSS and measurement sensitivities.
Survey results are presented in Section 5.0. This section includes a summary of the FSS measurements performed in the SDPTSSE survey units, comparison to the DCGL, tests performed and an evaluation of residual contamination levels relative to the ALARA criterion.
Supporting information is contained in Appendices. Appendix A contains photos and schematics to supplement the text. Survey design maps and tables of coordinates for the measurement locations in each survey unit are provided in Appendix B. Soil sample analysis results are provided in Appendix C.
2.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Description The PBRF site is located near the northern edge of the 6400 acre Plum Brook Station. The site, as described in the NRC license that controls decommissioning activities, comprises 27 acres which contain the Reactor Building and support buildings and facilities.2 The controlled-access site is bounded on the south by Pentolite Rd., on the west by Line 2 Rd. and on the north and east by a boundary fence. The southwest corner of the site, the intersection of Line 2 and Pentolite Roads is used as a reference location. 3 The coordinates are 410 23' 03.73" North Latitude and 820 41' 05.80" West Longitude.4 Figure 1 shows the principal PBRF buildings and site layout.
The site is generally level with grading to promote surface water drainage to the Water Effluent Monitoring System (WEMS) located at the south east corner of the site [USACE 2004]. The site reference grade level at the Reactor Building is 631 ft. above mean sea level
[NACA 1956].'
The PBRF 27 acre site contains several multi-story buildings and multiple support structures.
Below-grade structures and utilities extend throughout the site. These include underground pipe and utility tunnels, storm drains, catch basins, sanitary sewers, water and gas supply lines, cathodic protection wells and ground water monitoring wells. Prior to the beginning of 2 See Technical Specifications for the License No. TR-3 (Amendment 13) and License No. R-93 (Amendment 9) [NASA 2007].
Prior to decommissioning, the Reactor Vessel center was typically used as a local reference location for the PBRF.
4 Note that the coordinate grid system used for construction of the PBRF was a local coordinate system established by the Army Corps of Engineers in the 1940's for construction of the Plum Brook Ordinance Works. This local grid system has been balanced (tied in) to the Ohio regional state plane coordinate system by NASA to align Glenn Research Center and Plum Brook Station geographic references with modem high-accuracy geo-reference systems. This provides the ability to reference locations specified on historical drawings to global latitude and longitude [Hagelin 2010].
The finished floor elevation of the Reactor Building first floor is designated as the 0 ft. elevation for major PBRF buildings. This is one ft. above grade level at the Reactor Building location.
2
Plum Brook Reactor Facility FSSR, Rev. 0 decommissioning, buildings, water processing structures (WEMS, sludge basins, Cold Retention Basins (CRBs), etc.) paved roadways, parking areas, sidewalks and equipment pads covered about 25% of the site.. The remainder of the site surface was open land soil areas.
Areas adjacent to the PBRF on the north (north of North Rd.) contained utilities and support facilities for PBRF operations. These included the Assembly Test and Storage (ATS)
Building, the former Reactor Office Building (ROB), an electric substation and a deionized water storage tank. All these facilities and the surrounding land area were cleared of licensed radioactive materials and released from the PBRF NRC licenses prior to decommissioning of the PBRF.6 2.1 History of Site Operations Plum Brook Station was formerly a World War II era explosives manufacturing facility and prior to that was occupied by family farms and orchards [Bowles 2006].
Construction of the Plum Brook Ordinance Works (PBOW) in 1941-42, involved razing of existing farms, residences and small commercial buildings and construction of explosives manufacturing facilities. After World War II, the PBOW lay dormant for 10 years. In 1955 the Department of the Army transferred 500 acres in the northern portion of the former Ordinance Works to the National Advisory Committee on Aeronautics (NACA), the NASA predecessor, for construction of the Plum Brook test reactor facility.
The first tasks in the PBRF construction were to remove the PBOW facilities and clean up chemical residues from explosives production. This included removal and cleanup of two large chemical waste water retention basins located in the southeastern portion of the present-day site.
Construction of the Plum Brook Reactor and associated facilities required extensive excavation and backfilling. Soil was excavated to bedrock and bedrock was excavated in construction of the Reactor Building and nearby support buildings and in construction of large water handling facilities, the CRBs and Emergency Retention Basin (ERB) [USACE 2004].
Major PBRF milestones are listed below: 7 1956 - September, groundbreaking for PBRF.
1956 - Reactor Building construction initiated.
1959 - 1960 Major building construction completed.
1961 - June, 60 MW Test Reactor critical.
6 License Number TR-3, Amendment No. 6, approved by NRC letter dated Dec. 17, 1976.
7 Information sources for the site history include construction drawings and photos, PBRF operating cycle reports, PBRF annual reports, memoranda and other historical files maintained by PBRF Document Control.
3
Plum Brook Reactor Facility FSSR, Rev. 0 1973 - January 5th, Reactor shutdown.
1973 - June 30, PBRF facilities placed in "standby" condition.
1985 - Initial radiological characterization, Teledyne Isotopes Inc.
1989 - Follow-up radiological characterization, GTS-Duratek.
2002 - Decommissioning Plan approved. Equipment removal and initial building decontamination commenced.
2005-2010 - Decommissioning of Buildings and Excavation of Soil and Materials.
2010-2011-FSS on Storm Drains, Pipe Trenches and Other Sub-Surface Excavations.
It is noted that the major buildings were completed in the construction period, 1956 -
1960, but modifications to the site that affected areas excavated during decommissioning occurred throughout the operations period. These included installation of cathodic protection wells (1961-62), construction of the Waste Handling Building (1962-64), construction of the Assembly and Test Storage Building (ATS, Building 1142) utility and personnel passage tunnel to the Reactor Building (1964-65),
WEMS modifications (several times during 1961 - 1973) and modification of storm drains (1968).
2.2 Site Geology and Soil Description The Plum Brook Station and the PBRF site are underlain by shale and sandstone formations at varying depths (approximately 2 to 25 ft.) across the station with surface outcrops at some locations. The depth to bedrock is about 25 ft. in the vicinity of the Reactor Building [NASA 2007a]. Surface deposits constitute a mixture of soils derived from fine sand, silt, clay and unconsolidated glacial till [NASA 1959]. Soils in the vicinity of the PBRF are composed of loam, loamy fine sand and fine sandy loam
[USACE 2004].
However, the PBRF site soils are highly disturbed and not considered characteristic of native-undisturbed soils in the site vicinity. A series of major disturbances have occurred dating back to the 1940's. Construction of the PBOW involved extensive excavation to construct the ordinance "production lines" and process waste water retention basins. As a result of PBOW operations from 1942 - 1945, the PBRF site was extensively contaminated with chemicals used in the manufacture of Pentolite. 8 A site cleanup campaign was mounted prior to PBRF construction [Bowles 2006].
During this cleanup, unknown quantities of soil were reportedly removed from the site 8 Pentolite is a military grade high explosive.
4
Plum Brook Reactor Facility FSSR, Rev. 0 and fill material was likely brought in from off-site [USACE 2004]. And, as described in the previous section, construction of the PBRF involved extensive excavation and backfilling throughout the 27 acre site.
2.3 Site Soil Characterization Site soil characterization results are summarized to identify soil areas requiring remediation (excavation) and to present radionuclide profiles of radiological constituents of PBRF origin. Radiological characterization of PBRF soils has been performed on several occasions after the facility shutdown in 1973. The initial post-shutdown characterization survey performed in 1985 (reported in 1987) by Teledyne Isotopes, Inc. included sampling and analysis of site soils [Tele 1987]. In 1998, GTS Duratek performed a characterization survey to confirm the 1985 Teledyne results and to provide additional data on isotopic composition of contamination. From these studies, it was concluded that the ERB, the Pentolite Ditch, the CRBs and several localized areas required remediation. 9 In 2004, a comprehensive characterization survey of the site was performed by Montgomery Watson to identify contaminated soil areas and develop radionuclide profiles to guide remediation efforts. The area inside the PBRF site was divided into 11 survey units. Two areas outside the site fence that were known to be contaminated were also characterized; an area east of.the WEMS and the Pentolite Ditch.
Altogether, 610 surface and 1,043 subsurface soil samples were collected and analyzed by gamma spectroscopy [MWH 2005]. Selected samples were sent to vendor laboratories for analysis of non-gamma emitters.
Remediation action levels (RALs) to guide remediation planning were set at 50% of DCGLs published in the FSS Plan [MWH 2005a]. On this basis and from results of characterization surveys described above, the following areas were identified as requiring remediation:
- Emergency Retention Basin (ERB)
Cold Retention Basins Water Effluent Monitoring System (WEMS)
Storm Drains and Catch Basins Waste Handling Building (WHB) and Fan House (FH) Building sub-foundation (portions)
Pentolite Ditch and Environs, identified as Areas of Concern (AOCs) 9 It is noted that the Teledyne and GTS Duratek surveys were performed prior to the issuance of the current release criteria in 1 OCFR20 Subpart E and the supporting guidance on acceptable methods for characterization and final status surveys to demonstrate compliance. The 1985 and 1998 surveys relied heavily on gross activity analysis of soil samples and exposure rate measurements. These surveys identified locations of contaminated soil but did not provide information needed to determine nuclide profiles, DCGLs, and action levels for remediation and final status survey of site soils.
5
Plum Brook Reactor Facility FSSR, Rev. 1 In addition, several discrete contaminated areas that resulted from spills were defined. Subsequent to the MWH characterization surveys, additional characterization was performed to further delineate these spill areas. 1 0 They are summarized in Table 1 and Figure 1 shows their locations on a map of the PBRF site.
Table 1, Spill Area Summary Name Location Approximate Description Size (ft) (')
Spill Area No. 1 Along E half of PPH S Contaminated concrete, asphalt and soil wall 25 area. Cs-137 up to 1.67 pCi/g & Co-60 up to 4.48 pCi/g (in soil 0 to 6 in depth).
Designated as a Co-60 area. (2)
Spill Area No. 2 N of Reactor Building Site of a 300 gallon liquid spill during near Catch Basin 4 transfer of contaminated water in 2005.
Was remediated in 2005. Designated as a Co-60 area. (3)
Spill Area No. 3 E side of Hot Lab at Cs-137 up to 431 pCi/g & Co-60 up to Rollup Door 1000 271 pCi/g (0 to 6 in depth).
Designated as a Co-60 area. (3),
Spill Area No. 4 S of WHB Smaller of two distinct sub-areas (small area) 22 identified as Spill area No. 4. Above scan RAL, but no soil samples > 0.5 x DCGL.
(3)
Spill Area No. 4 W of Line 3 Rd Larger of two distinct sub-areas (main area) approximately 100 ft. S 2400 identified as Spill area No. 4. Scan of WHB results > bkg., but below scan RAL; no soil samples > 0.5 x DCGL. (3)
Spill Area No. 5 S of South CRB 600 Above scan RAL, but no soil samples>
u600 0.5 x DCGL. (3)
Spill Area No. 6 E of SEB & S of Sludge Scan surveys in 2006 failed to detect Basins levels above bkg., except in one very 2500 localized area (- 2ft2) just south of catch basin CB-9A, which was > RAL. (3)
WEMS Spill Area E of WEMS outside Soil area contaminated from WEMS Perimeter Fence 2500 overflow-flood events. Cs-137 up to 19.1 pCi/g & Co-60 up to 1.28 pCi/g (0 to 6 in depth). (3)
Table 1 Notes:
I 1.
2.
3.
Approximate surface area of potentially impacted areas investigated.
Descriptive information and survey results from SR-3 Descriptive information and survey results from SR-16 and personal communication, FSS supervisor.
Using characterization survey results, radionuclide profiles were developed for the areas that were identified as requiring remediation. These were published in a technical basis document to establish radionuclide mixtures and DCGLs for FSS of 10 Survey Request SR-3, Spill Area No. 1 (January 2006) and SR-16, Spill Areas No.2 through No.6 (May 2006).
6
Plum Brook Reactor Facility FSSR, Rev. 1 the site soils [PBRF 2009]. The site and impacted adjacent environmental areas were divided into groups with similar radionuclide profiles.
Figure 1, PBRF Site Map Showing Spill Areas 7
Plum Brook Reactor Facility FSSR, Rev. 1 Activity fractions of the principal radionuclides, Cs-137, Co-60 and Sr-90 were established for each group. The results are shown in Table 2.11 Table 2, Principal Radionuclides and Activity Fractions for Site Soils Location Activity Fractions Cs-137 Co-60 Sr-90 Default for PBRF site and Spill Areas 4, 5 &
0.912 0.007 0.081 6.
Spill Areas 1, 2 & 3 0.201 0.714 0.085 Environs Outside 0.878 0.037 0.085 Perimeter Fence Pentolite Ditch and 0.969 0.014 0.017 Environs 2.4 Storm Drain System Operation The Storm Drainage System (SDS) was designed to control and record the volume of surface and wastewater and their associated radioactivity levels to document compliance with Atomic Energy Commission (AEC)/NRC and other regulatory requirements. The storm drainage system bounded the 27-acre reactor site and the effluent was directed to a control point located in the southeast comer of the reactor site adjacent to and inside the PBRF fence. That control point was called the Water Effluent Monitoring Station/System (WEMS), Building 1192, [PBRF 2009b].
The WEMS had built-in capabilities for automatically closing the WEMS sluice gates when radioactivity levels exceeded pre-set limits. These limits were set to preclude the release of radioactivity level releases that would exceed the Federal limits in the PBRF license. Liquid effluents (such as storm drainage, waste waters including man-made radioactive contamination of PBRF origin, and processed lake dilution water) were released into the Pentolite Ditch via the WEMS.
During operation, the WEMS sluice gates closed numerous times for a variety of reasons ranging from detected high radioactivity levels, equipment malfunctions and weather related conditions like freezing and flooding conditions. When the WEMS sluice gates closed, planned radioactive discharges were terminated and the effluent waters were usually permitted to backup in the effluent trenches or were pumped into a 5 million gallon Emergency Retention Basin (ERB) for temporary storage.
1 Other radionuclides have been measured in PBRF characterization soil samples. In the FSS Plan, soil DCGLs were published for eight radionuclides (Co-60, Cs-137, Sr-90, Eu-152, Eu-154, Fe-55, Ni-69 and Ni-63. The dose to the Resident Farmer from radionuclides other than the principal three was calculated to be only 0.5 mrem/y. Hence, as this dose is well below the NRC 10% criterion, these radionuclides are considered insignificant.
8
Plum Brook Reactor Facility FSSR, Rev. I The SDS was originally constructed in the 1959 to 1963 time frame. 12 Major modifications were made to the system several times to improve performance such as adding a hydro-mat liner to the open ditches, reshaping the flow path, and subsequently adding concrete piping and covering the ditches.13 The storm drainage waters contributed to the dilution of controlled radioactive discharges; they also contributed to flushing of the drainage ditches during periods of heavy rainfall. Occasionally, storm waters washed radioactive contaminants from spills and fallout from nuclear bomb testing during the early 1960s that had settled on the ground into the ditches. Storm flow rates varied from low flows during minor rainfalls to high flow conditions during heavy rain falls.
The main on-site storm drainage system, post shutdown, consisted of five laterals plus an under-drain system. A map identifying the storm drain system including an identification of the laterals is contained in Exhibit 2 of Appendix A. A description of the lateral system is as follows:
- Lateral A: Started at Catch Basin 5A near Building 1191 and ran south then east to the WEMS. Lateral A was comprised of about 465' of 30" Rigid Corrugated Pipe (RCP) and 1000' of 18" RCP along with the remains of the hydro-mat liner. Lateral A ran under Line 3 Road in a 43"x 27"x 60' corrugated metal pipe. Laterals C and D joined Lateral A at the south end of Line 3 Road - Lateral C on the west side and Lateral D on the east. (Note-Lateral B was the Pentolite Ditch and was outside the PBRF fenced site.)
- Lateral C: Started at Catch Basin 13A south of Building 1133 and ran to Lateral A along the west side of Line 3 Road. Lateral C was comprised of about 360' of 12" RCP along with the remains of the hydro-mat liner.
- Lateral D: Started at the headwall and Catch Basin 7A near the north Cold Retention Basin and ran south along the east side of Line 3 Road, finally connecting to Lateral A. Approximately 70' of hydro-mat liner (intact) was abandoned near the junction of Lateral D and Lateral A because it originally entered Lateral A at a 450 angle, instead of the present (near 900). There was approximately 650' of 18" RCP, the remains of the hydro-mat liner, plus 50' of 18" RCP added to straighten the lateral where it connected to Lateral A.
0 Main Lateral: Started at the headwall north of Catch Basin 9A and near the raw water flush valve (25V 18) pit and runs south to the WEMS settling basin. There were approximately 880' of 36" RCP and the remains of the hydro-mat liner.
- The north lateral ran east and west on the north side ofthe facilityjust inside the north fence line. This lateral connected to the main lateral east of the sludge settling basins (1153).
- Under Drain System: An under drain system was added to drain ground water from under the concrete pipe in Lateral A and the main lateral. This 12 NASA Lewis Research Center - Plum Brook Station Building Plans, NASA PBRF Records Files and Drawings CF-115330 and 115332.
13 NASA PBRF Drawings PF-06006 & PF-06007.
9
Plum Brook Reactor Facility FSSR, Rev. 1 was a 6" Corrugated Metal Pipe (CMP) that ran approximately the last 275' of Lateral A and the last 350' of the main lateral emptying into the WEMS settling basin.
The term "lateral" was historically applied to the original open ditch areas of the PBRF storm drainage system.14 Other sub-surface storm drainage piping fed into three laterals and was not included in the "lateral" descriptions in this report. For example, there were storm drain sections north of Lateral A headwall that tied directly into Lateral A (CBs 1A, 2A, 3A, 4A, 23, 24, 25, 26, 27, 28, and 33). Also, storm drainage piping south of the headwall tied into Lateral A (CBs 18, and 22 plus three field drains). The areas outside the "lateral" descriptions are addressed in this FSS report.
In addition to the above laterals, there were a number of under-drains and sloped landscaping throughout the site that directed rain and ground water to catch basins.
These features were to keep the grounds relatively dry. The SDS consisted of a total of 9200 ft. of pipe ranging in size from 2" to 36" and a total of 56 catch basins.
A map of the SDS is provided in Exhibit 2 of Appendix A. See Exhibits 4, 5, and 9 in Appendix A for photographic documentation of Storm Drains, Pipe Trenches &
Other Sub-Surface Excavations prior to remediation.
The Cold Retention Basins, Building 1154, were located east of the Fan House and the Waste Handling Building and on the east side of Line 3 road. The two CRBs were designed as a hold area for quadrant and canal water associated with the 60MW test reactor and mock-up reactor operations. The stored water contained in the CRBs was sometimes released to Lateral D under controlled conditions, after sampling and analysis. The basins were mostly below grade with a roof section that was about 1-2 ft. above grade. The north basin was identified as CRB-1 and the south as CRB-2.
The Fan House (FH), Building 1132, was located south of the Primary Pump House (PPH) and east of the Hot Lab (HL). Primary FH functions were collection and processing of exhaust air and contaminated water from the Reactor Building and other PBRF buildings. Air processing equipment contained in the FH included fans, pumps, compressors, a scrubber, filters, activated carbon absorbers, radiation monitor and exhaust system.
The Waste Handling Building (WHB), Building 1133, was located south of the FH and east of the Hot Retention Area (HRA). The WHB contained equipment for processing contaminated water, protective clothing, miscellaneous contaminated trash, or dry active waste (DAW), equipment and experiment hardware. Waste processing activities spanned decontamination, waste shipment and recycling. The WHB included laundry facilities for decontaminating protective clothing. It contained operating areas for processing and packaging radioactive waste for offsite shipment, an evaporator facility for processing high-solids contaminated waste water and work areas for decontaminating reusable equipment and for packaging 14 PBRF reference drawing RF-06260.
10
Plum Brook Reactor Facility FSSR, Rev. 1 radioactive waste for storage and shipment. The WHB was designed for operation in close conjunction with the FH and HRA for processing PBRF radioactive wastes.
The Hot Retention Area (HRA), Building 1155, was located south of the FH and west of the HRA. The HRA was designed to provide holding capacity for large volumes of radioactively contaminated water generated in PBRF reactor operations.
It functioned as a tank farm for storage, holdup and decay of water from the hot drain system. The hotdrain system collected radioactive water from hot sumps in the Reactor Building and the other PBRF buildings. The twelve HRA tanks had a combined capacity of 512,000 gallons. Eight large (60,000 gallon) steel tanks were housed in the vault and four stainless steel, 8000 gallon tanks were buried underground north of the main HRA vault.
Additionally, a large number of underground piping systems were connected to many of the buildings at PBRF including the following: FH, PPH, WHB, Reactor Building, HL, CRBs, SEB, ROLB and the HRA. These piping systems included the following: primary and secondary cooling, contaminated discharge lines, resin
-transfer lines, valve pits, sewage systems, domestic water system, ventilation system piping, vent and drain lines and utility supply lines.
2.5 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Construction During the construction phase of the Reactor Facility (1956 to early 1963) prior to reactor full power operations, the lateral drainage ditches A, C, D and the main laterals were constructed as open ditches. The main lateral was open from Catch Basin 6B just north of the Precipitator (1157) and east to near the east fence line, then south to the WEMS. Lateral A was an open ditch running south from the Reactor Security and Control Building (RSCB) to near the south fence line then east to the WEMS. A 60 foot long 43"x 27" CMP ran under Line 3 Road. The spoils from the ditching were used to fill an existing creek bed that ran through the center of the facility. Pentolite Ditch that ran east and west from the WEMS exit to Plum Brook, was denoted as Lateral B.
Lateral C was an open ditch from the Fan House along the west side of Line 3 Road south to Lateral A. Lateral D was an open ditch from CRB-1 along the east side of Line 3 Road and south to Lateral A.
Piping and catch basins were eventually installed in the north and main lateral from the precipitator east and around the sludge settling basins then south to a headwall near the valve pit (25V1 8) and raw water flush line. Piping was installed in Lateral C from the Fan House south to near the Waste Storage Pad and Catch Basin 13A.
Early during the 60 MW reactor operations period, the storm drainage system laterals from the headwalls' 5 to the WEMS were open ditches lined with a hydro-mat lining 15 PBRF print number PF-65156.
11
Plum Brook Reactor Facility FSSR, Rev. I and sealed with a cold mastic sealant. The Hot Retention Area (HRA) pump out line discharged effluent into the storm drainage system adjacent to the valve pit near Cold Retention Basin (CRB) # 1. This location was just north of what was to be catch basin 7A. The headwall was visible near catch basin 7A.
The floor drain system for the Hot Lab Building Room 8, Change Room, 16 floor drains and the Mezzanine Room 27 floor drains 6 exited the south end of the building at -3 foot elevation and connected to the storm drainage system toward Catch Basin 3A.
The HRA and the CRB pump out lines also emptied into Lateral D near CRB-1.
This water flowed (undiluted) south to Lateral A then east to the WEMS settling basin where it finally mixed with raw water from the main lateral and was diluted to meet effluent release criteria.
Over time, the hydro-mat liners were prone to leakage because of weathering causing cracked joints and required significant maintenance. It was found that the material used was not suitable for that purpose and suffered significant damage from the sun.
In 1968, the bottoms of the hydro-mat liners were cut out and unstable base material removed. It is not known where this material was disposed. The ditch bottoms were then graveled and reinforced concrete pipe (RCP) installed. The hydro-mat liner remained in place on the ditch sides. An under drain system was installed on Lateral A and on the main lateral for a distance of about 300' from the WEMS settling basin.
There was an angled corner between Lateral D and the Lateral A east - west section that was squared off also at this time. New piping was also installed for the HRA pump out system, so that the discharge went between CRB 1 and CRB 2 and into the main lateral that runs north and south along the east fence line. The pipe discharged into catch basin 8A and then into the 36" reinforced concrete pipe, which empties into the WEMS settling basin (Facility Change 67-011). This afforded a better mixing of the HRA discharge water and the raw dilution water and reduced the frequency of WEMS gate closures. The CRB pump out discharge remained in Lateral D.
The CRBs were two prism based concrete basins with a capacity of about 500,000 gallons each. The basins were 94 ft. square at the top, 22 ft. square at the bottom and 18 ft. deep. Each basin had a pump that returned stored water to the Quadrant and Canal system. This water could also be pumped to the effluent trench (lateral D of the WEMS system) or transferred between basins. Valving was done in a below grade valve pit located just west of CRB-1. The valve pit was 14.3 ft. long, 10 ft.
wide and 7 ft. deep. All electrical feed was through the valve pit to control panels located on the west side of each basin.
16 PBRF print number PF-04587.
12
Plum Brook Reactor Facility FSSR, Rev. 1 2.6 Final Configuration and Scope of Remediation of SDPTSSE for Final Status Survey As areas became available, SDPTSSE were remediated by initially excavating the impacted soil/material and then performing subsequent remediation of areas identified by radiological survey results. When-surveys indicated that the action level was met, the area was remediated. When surveys indicated that the survey area was below the Remediation Action Level (RAL), no remediation was performed.
Remediation continued until surveys indicated that the area was below the RAL.
The final configuration of the Storm Drains, Pipe Trenches & Other Sub-Surface Excavations for FSS consisted of a ditch that was excavated and benched, if necessary, as shown in Exhibits 8,11, 12, 14, 16, 17 and 19 of Appendix A.
2.6.1 Storm Drain System Dismantlement The SDS was dismantled in phases by Decommissioning Contractor in accordance with Work Execution Package (WEP) number PBRF-WEP-09-020, "Storm Drain System Dismantlement". See Figure 2 and Exhibit 1 of Appendix A for a graphical representation of the Storm Drain, Pipe Trench and Other Sub-Surface Excavations conducted at PBRF. The phases of SDS dismantlement were as follows:
Phase 1 the West Storm Drain System dismantlement consisted of the following:
o Approximately 520 linear feet (ft.) of piping between CB-28 and CB-4A, o
CB-28, o
CB-1A, o
Roof drain line (DL) to STS-45, o
(Note-STS is used for "storm system" on some PBRF data sheets to designate pipe sections.)
o Cold Sump line to STS-45, o
SDS from STS-45 to CB-2A, o
Roof drain line to CB-2A, o
CB-27, o
SDS between CB-27 and CB-4A, o
CB-2A, o
SDS between CB-2A and CB-4A, o
Approximately 190 linear ft. of SDS piping between Hot Laboratory (HL), Building 1112 and CB-3A, o
Roof DL STS-82 from southeast end of HL to south end of STS-82, o
STS-1 12 from HL to STS-82, o
STS-82 from south end of STS-112 to CB-3A, o
Approximately 180 linear ft. of STS between CB-26 and CB-3A o
CB-26, STS-9, CB-25, STS-24, STS-64, CB-23, STS-75, CB-3A o
Approximately 190 linear ft. of SDS piping from CB-3A to CB-33 and from CB-4A to CB-5A, 13
Plum Brook ReactorFacility FSSR, Rev. 1 o
STS-53, CB4A, STS-54, CB-33, STS-70, and CB-5A.
- Phase 2 dismantlement of the Storm Drain System North of Reactor Building (RxB), Building 1111, consisted of the following:
o Approximately 687 linear ft. of SDS between CB-1 and STS-72, o
CB-1 and STS-36, o
STS-39, o
CB-4 and STS-37, o
STS-41, o
SDS from CB-3 to west end of STS-42 and CB-3, o
STS-42 from south end of Unit Sub Station 3 to CB-4, o
CB-4 and the SDS between CB-4 and CB-5.
Phase 3 dismantlement of the Storm Drain System East of the RxB consisted of the following:
o Approximately 283 linear ft. of SDS between CB-10 and STS-71, o CB-10, STS-2, CB-9, STS-4, CB-8, STS-3, CB-7, and STS-71.
Phase 4 dismantlement of the Storm Drain System West of the SEB consisted of the following:
o Approximately 400 linear ft. of SDS between CB-7A and STS-57, o
CB-7, STS-20, CB-21, STS-23, CB-20, STS-22, CB-12, STS-59, CB-11, and STS-57.
Phase 5 dismantlement of the Storm Drain System North of the North Road consisted of the following:
o Approximately 175 linear ft. of SDS between Man Hole MH-E4 and STS-73, o
MH-E4, CB-B6 and STS-73, o
Approximately 285 linear ft. of SDS from STS-56 to STS-65, o
STS-56, MH-E5, and STS-65, o
Approximately 195 linear ft. of SDS from CB-5 to STS-58, o
CB-5, STS-74, CB-6A, and STS-58, o
Approximately 215 linear ft. of SDS from Reactor Services and Equipment Building (SEB), Building 1131, to STS-66, o
STS-78, o
STS-79 from north of SEB to STS-78, o
CB-6B and STS-66.
Phase 6 dismantlement of the Storm Drain System East of the RxB consisted of the following:
o Approximately 460 linear ft. of SDS between Blow-off Pit through CB-12A TO CB-9A, o
Blow Off Pit, STS-80, CB-12A, STS-67, CB-I IA, and STS-60.
o Approximately 220 linear ft. of SDS between the Valve Pits to the intersection of STS-77 and STS-62, 14
Plum Brook Reactor Facility FSSR, Rev. 1 o Valve Pits, STS-87, CB-10A, STS-63, STS-62 up to intersection of STA-77, o Approximately 610 linear ft. of SDS from CB-14 AND CB-17 TO CB-8A, o
STS-25, CB-17, STS-24, CB-15, STS-76, CB-16, STS-77, and the remains of STS-62, o Approximately 1,505 linear ft. of SDS from what remains of FH-1 10-I to CB-8A and then to the WEMS, o
FH-1 10-1, CB-8A, STS-68 to the intersection with STS-34, the remaining part of STS-68, CB-i 8A, and West Lateral-F2 to the intersection with STS-35, o
STS-35 from CB-18A to West Lateral-F2, o
West Lateral-F2, o
STS-69 to CB-17A, CB-17A and the remaining section of STS-69, o
Approximately 850 linear ft. of SDS from CB-I5A to WEMS, o
CB-15A, STS-30 up to STS-81, STS-81, o
STS-30, STS-46, CB-16A, and remaining SDS between CB-16A and the WEMS, o
West Lateral-Fl.
Phase 7 dismantlement the Southern Storm Drain System consisted of the following:
o Approximately 60 linear ft. of SDS between FH and CB-WH5, o
Cold sump line to CB-WH5, o
Approximately 465 linear ft. of SDS from CB-WH5 to STS-6, o
CB-WH5, STS-1 from north end of line connecting to WHB, o
Remaining STS-1, o
STS-13 FD from WHB to CB-WH4, o
STS-14 cold sump from WHB to CB-WH4, STS-15 roof drain from WHB to CB-WH4, o
CB-WH4 and STS-5, o
STS-83, o
CB-WH3 and STS-5, o
Approximately 240 linear ft. of SDS from west end of STS-1 1 to CB-
- 13A, o
STS-11, CB-WH2, STS-84, CB-WH 11, STS-88, STS-95, and CB-13A.
When each phase of the SDS was dismantled, final post remediation surveys were conducted and the excavated areas were turned over to the FSS group for isolation and control and final status survey. See Exhibits 7, 8, and 14 of Appendix A for photographic documentation of Radiological Surveys being conducted after SDS dismantlement. Once final status surveys were completed, the excavated areas were turned over to the Decommissioning Contractor for backfill. See Exhibit 18 of Appendix A.
NOTE; A list of the buried piping remaining shall be provided in Attachment # 17, "Buried and Miscellaneous Piping".
15
Plum Brook Reactor Facility FSSR, Rev. 1 2.6.2 Cold Retention Basin Dismantlement The Cold Retention Basins, Building 1154, were dismantled in phases by the Decommissioning Contractor in accordance with Work Execution Package (WEP) number PBRF-WEP-09-006, "Cold Retention Basin Dismantlement". See Figure 2 for a graphical representation of the Storm Drain, Pipe Trench and Sub Surface Excavations conducted at PBRF. The phases of CRB dismantlement was as follows:
- Roof system dismantlement including the roof, joists and girders,
- Internal systems disassembly including the pumps, piping, ladders, etc.,
- Concrete structure dismantlement,
- Sub-base material excavation, and
- Underlying soil survey and excavation.
Once the CRBs were dismantled in the sequence above, final post remediation surveys were conducted and the excavated areas were turned over to the FSS group for isolation and control and for final status survey. Once final status surveys were completed, the excavated areas were turned over to the Decommissioning Contractor for backfill. See Exhibit 10 of Appendix A.
2.6.3 Impacted Utility Excavations Impacted utilities were dismantled in phases by the Decommissioning Contractor in accordance with Work Execution Package (WEP) number PBRF-WEP-09-007, "Impacted Utility Excavation". See Figure 2 for a graphical representation of the Storm Drain, Pipe Trench and Sub Surface Excavations conducted at PBRF. The utility excavation was as follows:
" Utility isolation,
- Sanitary Sewer System (SSS) excavation of approximately 815 linear ft. of system piping running east to west along North Road. This includes the following piping:
o SanS-5, o
SanS-6, o
SanS-7, o SanS-4, and o
SanS-8.
- SSS excavation of approximately 585 linear ft. of system piping running between the FH (1132) and the WHB (1133). This includes the following piping:
o SanS-1A, o SanS-IB, o SanS-2, and o SanS-3.
16
Plum Brook Reactor Facility FSSR, Rev. 1
- Cold Retention Area piping excavation of approximately 1,393 linear ft. of system piping running between the CRBs (1154) and the FH (1132). This includes the following piping:
o CRB-5, CRB-4-1, CRB-3-1, and CRB-7-1. In addition to the valve pit outside the CRBs, o
CRB-1, CRB-2, CRB-3, and CRB-4.
" Hot Retention Area piping excavation of approximately 216 linear ft. of system piping running between the CRB valve pit and the FH (1132). This includes the following piping:
o FH-110-1 and FH-110 sump FH-110.
- Primary Pump House (PPH), Building 1132, and FH utility excavation of approximately 633 linear ft. of system piping surrounding the FH (1132) and the PPH (1134). This includes the following piping:
o RxB-134, o PPH-105, PPH-106, and PPH-107, o Resin and valve pit south of PPH, RP-01, RPHD-1, and RPHD-2, o
FH-103, o FH-112 and FH-113.
See Exhibit 3 of Appendix A for a map of the Sanitary Sewer System, at PBRF.
Once the Impacted Utilities were dismantled in the sequence stated above, final post remediation surveys were conducted and then the excavations were turned over to the FSS group for isolation and control and for final status survey. Once final status surveys were completed the excavations were turned back over to the Decommissioning Contractor for backfill. 17 See Exhibit 13 of Appendix A.
2.6.4 Spill Area Excavation Three Spill Areas were excavated, by the Decommissioning Contractor, in accordance with Work Execution Package (WEP) number PBRF-WEP-09-009, "Spill Area Excavation". See Figure 2 for a graphical representation of the Storm Drain, Pipe Trench and Sub-Surface Excavations conducted at PBRF. The spill areas were known low level waste spills-one near the Hot Lab Building east truck door, one in vicinity of Primary Pump House resin pits, and one adjacent to the Water Effluent Monitoring Station trench. See Exhibits 6 and 15 of Appendix A.
The extents of spill area excavation were based on pre-excavation survey, which were designed to identify the area and depth of excavation necessary to remediate the spill area.
Spoils from spill area excavations were segregated based on radionuclide characterization data. See Exhibit 20 of Appendix A.
Once the spill areas were excavated, final post remediation surveys were conducted and then the excavations were turned over to the FSS group for isolation and control 17 If a section of pipe was not excavated and dismantled in the manner stated above, then that pipe was not addressed in this report. The pipe will be addressed in Attachment 9, "Embedded Piping" or Attachment 17, "Buried Piping".
17
Plum Brook Reactor Facility FSSR, Rev. 1 and for final status survey. Once final status surveys were completed the excavations were turned back over to Decommissioning Contractor for backfill.
2.6.5 Removal of Storm Sewer South of SEB (RCRA Area Excavation)
The Storm Sewer South of SEB (Building 1131) was dismantled in phases by the Decommissioning Contractor in accordance with Work Execution Package (WEP) number PBRF-WEP-09-027, "Removal of Storm Sewer South of Building 1131 Excavation". See Figure 2 and Exhibit 1 of Appendix A for a graphical representation of the Storm Drain, Pipe Trench and Sub-Surface Excavation and Survey Unit Location map for PBRF. The phases of the dismantlement were as follows:
Phase 1 Resource Conservation and Recovery Act (RCRA) area excavation which consisted the following:
o Approximately 60 linear ft. of storm drain system piping from CB-13 to SEB (1131),
o CB-13, STS-27, and CB-14, o
STS-26, o
STS-25 and CB-15, o
Monitoring well EB-RA-05 and underground electrical lines and conduit that serviced recovery wells, RW-01 and RW-02.
Phase 2 RCRA area excavation which consisted the following:
o SEB (1131) air intakes and monitoring well EB-RA-05, See Exhibit 19 of Appendix A for photographic documentation of the RCRA spill area excavation.
Soil from RCRA area excavations were segregated and handled separately from other site soils. See Exhibit 20 of Appendix A. Once RCRA area excavations were completed, final post remediation surveys were conducted and then the excavated areas were turned over to the FSS group for isolation and control and final status survey. Once final status surveys were completed the excavated areas were turned over to the Decommissioning Contractor for backfill.
18
Plum Brook Reactor Facility FSSR, Rev. I Figure 2, Storm Drains, Pipe Trenches & Other Sub-Surface Excavation and Survey Unit Location Map PNTOLIý orci 3.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations History and Operations with Radioactive Materials During reactor operations, there were several areas, especially between the Primary Pump House, Hot Lab, and the Fan House, where minor spills of radioactive material occurred on the ground. During resin changes at the Primary Pump House Resin Pit, some area 19
Plum Brook Reactor Facility FSSR, Rev. 1 contamination did occur. Additionally, some area contamination occurred when the Hot Lab sump was cleaned in the general vicinity of the Hot Lab rollup door apron and the concrete sump cover. Although these areas were cleaned as much as possible, some low level of contamination found its way to the storm drainage system.
Catch Basin 10, which receives run-off water from the asphalt/gravel area between the PPH and FH, was contaminated shortly after shutdown. The catch basin was cleaned, but area contamination still existed to some degree inside the catch basin and also the 8" corrugated metal pipe which connects Catch Basin 10 to catch basin 9 and beyond. Additionally, contamination likely existed inside the 36" RCP from Catch Basin 8A to the WEMS settling basin. Low levels of contamination were likely present on the existing hydro-mat liner and under the hydro-mat liner of lateral D and beyond to the WEMS settling basin.
The storm drain system at and near the Waste Handling Building south rollup door apron was impacted by several minor spills. The area inside the rollup door was a posted contaminated area and several small spills of radioactive materials occurred just outside the door.
Prior to the installation of the concrete pipe, Lateral D and part of Lateral A were impacted by undiluted HRA discharges. This represented about 650' of liner in Lateral D and about 400' of liner in Lateral A before finally mixing with raw water at the WEMS Settling Basin.
After the installation of the concrete pipe, the main lateral was impacted from Catch Basin 8A to the WEMS. The Emergency Retention Basin also drained into the main lateral at Catch Basin 18A. See Exhibit 2 of Appendix A for a Map of the SDS Laterals.
When the concrete pipe was installed, approximately 7700 cubic yards of earth was required to bring the ditches back up to grade. It is not known where this backfill material was obtained.
3.1 Disposition of Materials in the Post-Shutdown Period Following termination of operations of the 60 MW and mock-up reactors on January 5, 1973 through June 3 0th of 1973, the WEMS remained active and was maintained in that condition until there was no radiological release hazard. The final end condition was that the WEMS was deactivated and the gates opened to the Pentolite Ditch. Prior to deactivation, the following conditions were met:
" No liquid radioactive waste discharges had occurred for two months,
" A rainfall of 1" in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and an accumulated rainfall of 2" had occurred, and
" The liquid effluent radioactively level had not exceeded 1x10"7 gaCi/ml beta-gamma and 3x1 0-8 gCi/ml alpha since the beginning of the two-month period.
Prior to shutting down the WEMS, the PBRF trenches, catch basins, settling basins and the WEMS inlet basin were flushed to remove slit and sand. Unnecessary loose equipment was removed from the WEMS Butler Building, as were scrap materials 20
Plum Brook Reactor Facility FSSR, Rev. 1 inside and outside; electrical heaters and other equipment were shutdown after a WEMS test and the building closed and locked.
Subsequent to July 1 st of 1973, the WEMS was controlled according to Nuclear Regulatory Commission Licenses TR-3, R-93 and Broad By-Product Material License BPL No. 34-06706-03. Periodic effluent sampling for radioactivity was conducted as part of the PBRF facility and environmental program to demonstrate compliance with federal regulations. Reports to the NRC provide the details of significant events or changes in status during the period between 1973 and the approval of the PBRF Decommissioning Plan in 2002.
Radiological characterization information to support decommissioning of PBRF was developed in the 1985 Teledyne Isotopes Characterization Survey and the 1998 GTS Duratek Confirmation Survey. The 1985 study indicated that the accumulated silt in catch basins had gross beta activity ranging from 7 to 330 pCi/g, with an average of 44 pCi/g. Depths and areas of contamination were not reported.
The catch basins were reexamined in the 1998 survey. The beta survey showed that one sample had a maximum concentration of 5,000 dpm/100-cm2, and the remaining samples had an average concentration of less than 1,200 dpm/100-cm 2. The 1998 gross beta gamma activity measurements were on the order of 15 to 20 pCi/g, similar to the 1985 measurements (44 pCi/g). The 1998 sampling effort also showed that the activity in the catch basins is predominately naturally occurring K-40 at concentrations from 7 to 14 pCi/g. The concentration of Cs-137 and Co-60 ranged from 1 to 11 pCi/g and from 1 to 5 pCi/g, respectively.
Following termination of reactor operations in early 1973, the storm drains, pipe trenches & other sub-surface systems remained active and were to be maintained in acceptable condition for effluent flows from the operable building groundwater sump pumps and storm drainage.
Before and after July 1st of 1973, the storm drains, pipe trenches & other sub-surface systems were controlled according to AEC/NRC licenses. Periodic effluent sampling for radioactivity was conducted as part of the PBRF facility environmental monitoring program to demonstrate compliance with AEC/NRC regulations for effluent discharges.
3.2 Decommissioning In general, the Storm Drains, Pipe Trenches and Other Sub-Surface Excavations were remediated in the following manner:
- Geographical boundaries of the area of excavation were marked, flagged or identified in some manner.
" Utilities were identified and de-energized.
- Area was cleaned and grubbed of vegetation.
SDPTSSE was excavated and safety boundaries were established.
" Excavations were inspected periodically.
" Areas remediated based on contamination levels.
21
Plum Brook Reactor Facility FSSR, Rev. I
" Excavation was guided by walkover scan surveys and excavated soil was segregated.
The soil >DCGL was shipped to an approved waste disposal facility.
Soil < DCGL was transported to the soil farming area, within the PBRF Restricted Area, for FSS.
Most of the soil < DCGL was surveyed and sorted using the MACTEC Development Corporation SS-Series Conveyor Soil Survey and Sorting System. The criterion for soil rejection was established for small and large material volumes. The small volume action level was established at the DCGL. The large volume action level was 50% of the DCGL. Rejected materials were staged for shipment to an approved waste disposal facility. 18 Post remediation surveys were performed to ensure that the remediation was complete. Results were compared to the scan action level which was set at 50% of the applicable DCGL.19 This Final Post Remediation (FPR) surveys and samples established that no further remediation was necessary prior to commencing Final Status Survey for the SDPTSSE. The Storm Drain, Pipe Trench and Sub-Surface Excavations were prepared for FSS and surveyed in accordance with the FSSP
[NASA 2007].
4.0 Survey Design and Implementation for Storm Drains, Pipe Trenches & Other Sub-Surface Excavations The survey design and implementation for SDPTSSE is as follows:
Section 4.1 discusses factors relating to FSS plan design requirements including the site specific DCGL values for soil, DCGL values for other media, radionuclide mixtures expected, surrogate DCGL values, equations used, area factors, survey unit size requirements and scan coverage requirements for Class 1 and Class 2 areas.
Section 4.2 discusses the area classification and survey unit breakdowns.
Section 4.3 discusses the number of measurements and samples conducted in each survey unit.
Section 4.4 discusses the instrument and measurement sensitivities.
4.1 FSS Plan Requirements The goal of the PBRF decommissioning project is to release the site for unrestricted use in compliance with the NRC's annual dose limit of 25 mrem/yr plus ALARA.
18 FSS of Excavated Materials is reported in the FSSR Attachment 18.
19 Investigation levels are established for 2"x2" Nal detector with Ludlum Model 2350-1 that is set up with either the Cesium-137 window or the Cobalt-60 window depending on the radionuclide distribution identified.
22
Plum Brook Reactor Facility FSSR, Rev. 1 The NRC dose limit applies to residual radioactivity that is distinguishable from background. The DCGL values established in the FSSP [NASA 2007] will not be increased without prior NRC approval.
4.1.1 Site-Specific DCGL Values for Soil The surface soil DCGL values are provided in Table 3-1 of the FSSP [NASA 2007] and listed in Table 3 of this report. The DCGL values are the volumetric activity concentrations of the first 6 inches of soil, in pCi/g, that will be used during FSS to determine compliance with the 25 mrem/yr unrestricted use criterion.
Table 3, DCGL Values for Surface Soil DCGL Radionuclide (pCilg)
Co-60 3.8 Sr-90 5.4 Cs-137 14.7 To provide a consistent level of analysis for the contamination of surface soil, a site-specific analysis approach was used for the PBRF. The dose model selected for analyzing residual soil contamination, the Resident Farmer exposure scenario was implemented in RESRAD Version 6.0.
Section 7.3.1 of the FSSP [NASA 2007] states that sub-surface survey units that have had remediation performed, shall have FSS performed and results compared to surface soil DCGLs.
The dose assessments and DCGL calculations for surface soil, are described in detail in Attachment B, "Approach and Basis for Development of Site-Specific Derived Concentration Guideline Levels (DCGL)" of the FSSP
[NASA 2007].
Model input parameters were developed and justified for each assessment and can be found in the FSSP, Attachment B, Tables B-i through B-8.
4.1.2 DCGL for Other Media In accordance with the FSS Plan [NASA 2007], the DCGL for sediment is the same as the surface soil. The DCGL for subsurface soil is the same as surface soil.
4.1.3 Radionuclide Mixture for FSS The evaluations of radionuclide mixtures for soil are contained in Attachment A of the FSSP [NASA 2007], "Radionuclide Distribution Basis for DCGL Determination, 23
Plum Brook Reactor Facility FSSR, Rev. 1 and FSS of the PBRF". Current and representative sample data were used to determine the final radionuclide mixtures for FSS.
Per NUREG-1757 [USNRC 2006], the Nuclear Regulatory Commission (NRC) Staff considers radionuclides and exposure pathways that contribute no greater than 10%
of the 25 mrem/yr dose criteria to be insignificant contributors. This 10% limit for insignificant contributors is an aggregate limitation only. That is, the sum of the dose contributions from all radionuclides and pathways considered insignificant is no greater than 10% of the dose criteria of 25 mrem/yr per 10 CFR Part 20, Subpart E.
For PBRF soil, the doses from all radionuclides other than Cs-137, Co-60, and Sr-90 totaled 0.5 mrem/yr. Because this dose is 2% of the 25 mrem/yr limit, all radionuclides other than Cs-137, Co-60, and Sr-90 were eliminated from further consideration. To ensure the 25 mrem/yr criterion is met, any open land survey unit
.where the mean of FSS soil sample results indicates that the dose may be greater than 24.5 mrem/yr is reviewed for compliance with the unrestricted use limit.
4.1.4 Surrogate DCGL and the Unity Rule There are two distinct types of surrogate DCGLs, at PBRF. The first surrogate DCGL is for surface soil scanning with Nal detector model 44-10 and the second is for surface and sub-surface soil sample analysis. Technical Basis Document TBD-PBRF-09-001, "Radionuclide Distributions and Adjusted DCGLs for Site Soils"
[PBRF 20091 developed a surrogate DCGL value (DCGLsuR) for the hard-to-detect (HTD) radionuclide of concern, Sr-90, using Cs-137 or Co-60. Table 2-1 of Technical Basis Document TBD-PBRF-09-001 provides the DCGLs for surface soil, based on analysis of numerous characterization sample results. Furthermore, NUREG-1757 allows for the de-selection of radionuclides that contribute no greater than 10% of the 25 mrem/yr dose criteria.
For PBRF soils, the dose from all radionuclides other than Co-60, Sr-90 and Cs-137 totaled 0.5 mrem/yr. Because this dose is only 2% of the 25 mrem/yr. limit, all radionuclides, other than Co-60, Sr-90, and Cs-137, were eliminated from further consideration. To ensure the 25 mrem/yr. criterion is met, the maximum allowable dose for Open Land Survey Units, at PBRF, shall be:
Maximum allowable dose for Open Land Survey Unit, at PBRF =
25 mrem/yr. (annual dose limit) - 0.5 mrem/yr. (the maximum dose from de-selected radionuclides) = 24.5 mrem/yr.
Table 5-2 of PBRF-09-001 provides the values for surrogate DCGLs for each open land area at PBRF. The values were derived from characterization sample analysis that was used to determine the isotopic mix of Co-60, Sr-90, and Cs-137 for that area. Based on the characterization data, the predominant radionuclide was determined to be either Co-60 or Cs-137, and the other radionuclides were surrogated to the predominant radionuclide.
24
Plum Brook Reactor Facility FSSR, Rev. 1 During scanning activities, the Nal detector is set up in the "windowed mode" to detect the predominant radionuclide for that area, either Cs-137 or Co-60. The other radionuclides are surrogated to the predominant radionuclide and the DCGLSUR are provided in Table 5-2 of Technical Basis Document TBD-PBRF-09-001.
During soil sample analysis, both Cs-137 and Co-60 can be easily detected by gamma spectroscopic analysis. Therefore, only Sr-90 needs to be surrogated to the predominant radionuclide. These soil sample DCGLsUR are determined in the survey design for that survey unit.
See Table 4 for the Surrogate DCGLs that were used for SDPTSSE FSS.
Table 4, Surrogate DCGLs for Soil FSS Scan Soil Location Activity Fractions Surrogate Survey Sample Radionuclide DCGLsUR DCGLSUR Cs-137 Co-60 Sr-90 (pCi/g)
(pCi/g)
Default for PBRF site and 0.912 0.007 0.081 Cs-137 11.55 11.82(1)
Spill Areas 4, 5
& 6 Spill Areas 1, 2 0.201 0.714 0.085 Co-60 3.28 3.50(2)
& 31 Emergency 0.878 0.037 0.085 Cs-137 10.31 11.40(3)
Retention Basin I
_I Table 4 Notes:
I.
2.
3.
Co-60 soil sample DCGL is 3.8 pCi/g, per Survey Designs 30, 33, 37 and 44.
Cs-137 soil sample DCGL is 14.7 pCi/g, per Survey Design 39.
Co-60 soil sample DCGL is 3.7 pCi/g, per Survey Design 46.
A unity rule calculation was performed on the sample results to quantify the total activity for each sample.
4.1.4.1 Surrogate Equation The surrogate DCGL is computed based on the distribution ratio between the hard-to-detect radionuclides and the easy-to-detect radionuclides. The surrogate DCGL is calculated using the following equation:
Surrogate,,,, =
II I(CGz.
DCGL2 DCGL' DCGI,,
(Equation 1)
Where: DCGLSUR = Surrogate radionuclide DCGL DCGL 2, 3... n = DCGL for radionuclides to be represented by the surrogate 25
Plum Brook Reactor Facility FSSR, Rev. I Rn = Ratio of concentration (or nuclide mixture fraction) of radionuclide "n" to surrogate radionuclide.
4.1.4.2 Unity Rule Equation The unity rule is typically used as the first test to evaluate compliance with radiological criteria for license termination when more than one radionuclide has been determined to be potentially present. In lieu of a single DCGL, a unity rule calculation is used to demonstrate compliance with the soil unrestricted use limit. A surrogate DCGL, if applicable, would be used in the unity rule calculation. The unity rule is:
C, C2 C.
1
-+
+......
DCGL, DCGL2 DCGL (Equation 2)
Where:
Ca= concentration of radionuclide n and DCGLn = DCGL of radionuclide n.
4.1.4.3 Area Factors The area factor is the multiple of the DCGL that is permitted in an area of elevated residual radioactivity without requiring remediation and still be in compliance with the release criteria. It is related to the size of the area over which the elevated residual radioactivity is distributed. That area, denoted AEMC, is generally bordered by levels of residual radioactivity below the DCGL, and is determined by an investigation. The area factor is calculated as the ratio of dose per unit area or volume for the default surface area for the applicable dose modeling scenario to the dose calculated using the area of elevated residual radioactivity, AEMC. Area factors for surface soil are provided in Table 3-4 of the FSSP [NASA 2007] and are shown in Table 5.
Area factor assumptions and calculations are provided in Attachment B of the FSSP [NASA 2007].
26
Plum Brook Reactor Facility FSSR, Rev. 1 Table 5, Surface Soil Area Factors Elevated Area 1
2 3
5 10 15 25 100 250 2,000 (m2)
Area Fa 10.4 6.2 4.7 3.4 2.3 1.9 1.6 1.2 1.1 1
Factor 4.1.4.4 Survey Unit Size Survey units are typically limited in size to ensure each area is assigned an adequate number of data points. The survey unit sizes for PBRF are provided in Table 4-1 of the FSSP [NASA 2007] and in Table 6. Note that the maximum survey unit size for Class 1 surface soils is 2,000 in2.
Table 6, Recommended Survey Unit Area Size Requirements for FSS Class Land 1
up to 2000 m2 2
up to 10,000 m2 3
Up to 100,000 M2 4.1.4.5 Scan Coverage for Class I Areas The area covered by scan measurement is based on the survey unit classification. A 100% accessible area scan of Class 1 survey units is required. No Class 2 or Class 3 survey units were identified within the SDPTSSE. Minimum scan survey coverage requirements for the PBRF are provided in Table 5-1 of the FSSP [NASA 2007] and Table 7 below.
Table 7, Minimum Scan Survey Coverage By Classification Scan Survey Coverage Class 1 Class 2 Class 3 Scan Coverage 100%
10 to 100%
Minimum of 10%
27
Plum Brook Reactor Facility FSSR, Rev. 1 4.2 Area Classification and Survey Unit Breakdown At the time the FSSP [NASA 2007] was initially submitted to the NRC for review and approval, the SDPTSSE areas were not fully characterized or remediated. The only reference to SDPTSSE areas identified in the FSSP is provided in Table 2-2 and states that Drainage Systems (Storm Sewers) are Class 1 areas. Therefore, based on the information provided in the FSSP and that remediation was conducted in the SDPTSSE areas, all SDPTSSE are considered Class 1 areas.
Refer to Figure 2 and Exhibit I of Appendix A for a location map of each survey unit. Table 6 provides the current classification of the area and the corresponding FSSP [NASA 2007] classification for the area. See Appendix B for a map of each specific survey unit contained within this report.
Table 8 was reviewed to ensure that no areas were classified "downward" from classifications assigned in the FSS Plan [NASA 2007]. "OL" refers to "Open Land".
Table 8, Storm Drains, Pipe Trenches and Sub-Surface Excavations Survey Unit Classification Comparison to FSSP Survey FSSP Unit Class Description Classification( 2 )
OL-1-1 1
Storm Drains - Section 2-1 1
OL-1-2 1
Storm Drains - Section 2-2 1
OL-1-3 1
Cold Retention Basin North 1
OL-1-4 1
Cold Retention Basin South 1
OL-1-5 1
Cold Retention Basin East West Ramp I
OL-1-6 1
Storm Drains Phase #1 1
OL-1-7 1
Storm Drains Phase 2, Section 1 1
OL-1-8 1
Storm Drains Phase 2, Section 2 1
OL-1-9 1
Storm Drains W, NW & N of SEB 1
OL-1-10 I
Storm Drains SE of PPH 1
OL-1-11 1
Phase 4, Section 1 1
OL-1-12 1
Storm Drains, Lateral D, North Section 1
OL-1-13 1
Storm Drains, Lateral D, North Section 1
OL-1-14 1
Storm Drains, South & East of SEB 1
OL-1-15 I
Storm Drains, Main Lateral, South of FH-I 10 1
OL-1-16 1
Storm Drains, Lateral A, East of Line 3 Road 1
OL-[-17 1
Storm Drains, Lateral D, South Section & STS46 1
Trench 28
Plum Brook Reactor Facility FSSR, Rev. 1 Table 8, Storm Drains, Pipe Trenches and Sub-Surface Excavations Survey Unit Classification Comparison to FSSP Survey C
FSSP Unit Class Description Classification(2 )
OL-1-18 I
SANS Trenches South of HL Building 1
OL-1-19 1
OL-1-20 1
Northeast Comer of FH/WHB Footprint 1
OL-1-21 1
Southeast Comer of FH/WHB Footprint 1
OL-1-22 1
Western Sections of FH/WHB Footprint 1
OL-1-23 1
UST Excavations I
OL-1-24 1
Evaporator Pit 1
OL-1-25 1
Phase 7 North of Haul Road, South of FH/WHB I
OL-1-26 1
ERB Sump Drain Line Excavation 1
OL-1-33 I
Storm Drain Excavation-MacTec Crossover 1
OL-1-34 1
Storm Drain Excavation-Crossover south of SEB I
OL-1-35 I
Storm Drain Excavation-Crossover at Line 3 1
Road/Driveway E Storm Drain Excavation-Line 3 Road North Crossover OL-1-37 1
Storm Drain Excavation-Line 3 Road South Crossover OL-1-38 1
Storm Drain Excavation-Haul Road Crossover 1
OL-1-39 1
Storm Drain Excavation - Trench South of Sludge 1
Basins, East of SEB OL-1-40 1
Storm Drain Excavation - CB-18 Excavation 1
OL-1-41 1
Storm Drain Excavation - CB-5A Excavation 1
OL-1-42 I
Resin Pits Excavation South of PPH 1
01-1-43 1
Storm Drain Excavation-Lateral C South Excavation 1
01-1-44 1
Storm Drain Excavation-Lateral C North Excavation 1
01-1-45 1
Excavations South of Waste Storage Pad I
Table 8 Notes:
- 1. The data provided in the description are provided in the Survey Unit Log and the Survey Unit Release Records. See Figure 2 for a map of SDPTSSE that identifies the survey unit locations.
- 2. The FSSP Classifications are based on Table 2-2 of the FSSP which identifies Drainage Systems (Storm Sewers) as being Class 1.
Table 9 provides the survey unit breakdown, by MARSSIM classification [USNRC 2000].
29
Plum Brook Reactor Facility FSSR, Rev. 1 Table 9, Storm Drains, Pipe Trenches and Other Sub-Surface Excavations Survey Unit Breakdown by MARSSIM Classification No. of Surface
% of Class Survey Area Survey
/ of Surface Average Area of Units (mi2)
Units Area Survey Units (m2) 1 39 25268 100 100 648 4.2 Number of Measurements and Samples The Final Status Survey for SDPTSSE was covered by several Survey Design and Survey Request (SR) documents. See Appendix B for specific sample locations within each survey unit. Table 10 identifies the Survey Design that was implemented for each SDPTSSE survey unit. The following Survey Requests (SRs) were used for SDPTSSE survey units: Survey Request Numbers 164, 165, 169, 176, 204, 237, 242, 244, 277 and 279.
The number of measurements and samples for each SDPTSSE survey unit was determined using the MARSSIM [USNRC 2000] statistical hypothesis testing framework as outlined in the FSS Plan. The Sign Test was selected because background soil concentrations are small when compared to the applicable DCGLw.
Decision error probabilities for the Sign Test are set at a = 0.05 (Type I error) and f3 =
0.10 (Type II error) in accordance with the FSSP.
The Visual Sample Plan (VSP) software was used to determine the number of FSS measurements in each survey unit within the SDPTSSE.2° When the Sign Test is selected, the VSP software uses MARSSIM [USNRC 2000] Equation 5-2 to calculate the number of measurements. Equation 3 of this report is Equation 5.2 from the MARSSIM and is shown below:
N 2(ZIa
+ Z,
)2 (Equation 3)
N=l1.2 (l*+Z-)
Where:
- 0"5j 1.2 = adjustment factor to add 20% to the calculated number of samples, per a MARSSIM requirement to provide a margin for measurement sufficiency, N = Number of measurements or samples, a = the type I error probability,
= the type II error probability, Zi., = proportion of standard normal distribution < 1 - a (1.6449 for a = 0.05),
Zl-p = proportion of standard normal distribution < 1 - 0 (1.2816 for P3
= 0.1),
(D (A/a) = value of cumulative standard normal distribution over the interval -00, A/a, 20 The FSS Plan (Section 5.2.4) states that a qualified software product, such as Visual Sample Plan0o [PNL 2010], may be used in the survey design process.
30
Plum Brook Reactor Facility FSSR, Rev. 1 A = the "relative shift", defined as the DCGL - the Lower Bound of the Gray Region (LGBR), and (Y = the standard deviation of residual contamination in the area to be surveyed (or a similar area).
The MARSSIM module of VSP [PNL 2010] requires user inputs for the following parameters: a, P3, A, a and the DCGLw. The number of measurements, N, for the 39 SDPTSSE survey units were calculated in six survey designs. Table 10 summarizes the survey design calculations and lists the values of the key VSP input parameters.
Table 10, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Survey Design Summary Design LGBR/
No.(1)(2)(3)
Survey Units(4 )
Class DCGL(5)
LGBR(s)
DCGL A
CT (
/Cr N
OL-1-1, OL-1-2 and 30 OL-1-6 1
11.55 11.26 0.975 0.29 0.11 2.64 11 33 OL-1-3 and OL-1-4 1
11.55 11.26 0.975 0.29 0.15 1.93 11 37 OL-1-3 and OL-1-5 1
11.55 11.26 0.975 0.29 0.15 1.93 11 OL-1-10, 1
3.576 3.05 0.87 0.45 0.15 3.0 11 39 OL-1-42, and 1
3.5(6) 3.05 0.87 0.45 0.15 3.0 11 OL-1-45 1
3.5(6) 3.05 0.87 0.45 0.15 3.0 11 OL-1-7, OL-1-8, OL-1-9, OL-I-11 through OL-1-25, 44 OL-1-33 through 1
11.55 11.26 0.975 0.29 0.10 2.90 11 OL-1-41, OL-1-43 and OL-1-44 46 OL-1-26 1
10.31 5.7 0.5 5.7 2.28 2.5 11 Table 10 Notes:
- 1. The data reported in Table 10 is taken from the Survey Design reports listed. They are maintained in the PBRF Document Control System.
- 2. Small differences in the values in this table and the values documented in the Survey Design reports are due to spreadsheet rounding and significant figures.
- 3. Values provided in the table are typical values for the survey units within that specific design.
- 4.
Survey Units OL-1-27 through OL-1-32 are located in the ERB and are covered in the FSSR Att.10.
- 5. Units are in pCi/g.
- 6. Co-60 DCGL.
Selection of design input parameters followed guidance in the FSS Plan. The Plan states that "the LGBR is initially set at 0.5 times the DCGLw, but may be adjusted to obtain a value for the relative shift (A/a) between I and 3".
The VSP software [PNL 2010] performs an analysis to examine the sensitivity of the number of samples, N, to critical input parameter values. The following is obtained from the VSP [PNL 2010] report for survey unit OL-1-26 in Design No. 46 (with modifications). The sensitivity of N is explored by varying the standard deviation from 2.28 to 4.56 pCi/g (an increase of 100%), with the lower bound of gray region from ranging from 50 to 70 % of the DCGL. The value of beta, probability of mistakenly concluding that the survey units mean concentration is greater than the DCGL is varied 31
Plum Brook Reactor Facility FSSR, Rev. 1 from 0.05 to 0.15. While the VSP [PNL 2010] sensitivity analysis also varies the value of a, the sensitivity of N to changes in a is not evaluated here.
Table 11 summarizes the results of this analysis. The region of most interest in the table is for a = 0.05 (required to be fixed), 03 = 0.10 (may be adjusted) and the LBGR at 50% to 70% of the DCGL. This range corresponds to A/a ranging from 1.5 to 2.5. The sensitivity of N to expected measurement variability is examined first. With the LBGR set to 60%, a = 0.05 and P3
= 0.10, a 100 % increase in a increases N from 12 to 23. At this LBGR value, N is sensitive to measurement variability. With the LBGR set to 50% of the DCGL, the sensitivity of N to a is decreased; a 100 % increase in a increases N from 11 to 17.
However, in contrast, the sensitivity of N to an incorrect conclusion that the survey unit will pass (owner's risk) is low. With the LBGR set at 60 %, of the DCGL (holding a and a constant) and increasing 03 from 0.10 to 0.15, decreases the number of measurements from 12 to 10. With the LBGR set at 50 %, of the DCGL, (holding a and a constant) and increasing P3 from 0.10 to 0.15, decreases the number of measurements from 11 to 9. These results show that N = 11 represents a reasonable number of measurements for FSS of the SDPTSSE, in view of parameter values applied to the designs.
Table 11, Sensitivity Analysis for OL-1-26 Design Number of Samples DCGL = 11.55 a a=0.05 (2) a=0.10 ax=0.15 a
4.56 Qc) a = 2.28 a = 4.56 a = 2.28 a = 4.56 a = 2.28 LBGR=70% 1
)(4) 13=0.05 44 18 35 14 29 12 13=0.10 35 14 27 11 22 9
13=0.15 29 12 22 9
18 7
LBGR=60%
13=0.05 28 15 23 12 19 10 13=0.10 23 12 17 9
14 8
13=0.15 19 10 14 8
12 6
LBGR=50%
13=0.05 21 14 17 11 14 9
13=0.10 17 11 13 9
11 7
13=0.15 14 9
11 7
9 6
Table 11 Notes:
- 1. Units of DCGL, a and LBGR are pCi/g.
- 2. a = alpha, probability of mistakenly concluding that p < DCGL.
- 3. a = Standard Deviation.
- 4. LBGR = Lower Bound of Gray Region (as % of DCGL). 13
= beta, probability of mistakenly concluding that p > DCGL.
Visual Sample Plan was also used to determine the grid size, the random starting location coordinates (for Class 1 survey units) and to display the measurement locations on survey unit maps drawn to scale.
If the scan sensitivity of the detectors used in Class 1 survey units was below the DCGLw, the number of measurements in each survey unit is determined solely by the Sign Test. If the scan sensitivity was not below the DCGLw, the number of 32
Plum Brook Reactor Facility FSSR, Rev. 1 measurements was increased as determined by the Elevated Measurement Comparison.
21 4.3 Instrumentation and Measurement Sensitivity Instruments used in the FSS of each survey unit were selected and identified in the appropriate survey design. Their detection sensitivities were shown to be sufficient to meet the required action levels for the MARSSIM [USNRC 2000] class of each survey unit.
Scan sensitivities for detectors used for walkover gamma scans of soil are determined using the method referenced in the PBRF FSS Plan and described in NUREG-1507 [NRC 1998]. Scan sensitivities for the Ludlum Model 44-10 Nal detectors used in FSS of soils at PBRF were developed in a technical basis document
[PBRF 2009a]. The method is summarized and the key equations presented. The scan MDC is calculated using the following equations adapted from NUREG-1507
[USNRC 1998] for gamma scanning with Nal detectors:
MDCRsURV d',rfi (60)
(Equation 4)
MDCscan-MDCRv Conv
- MSo (Equation 5)
Where:
MDCsuRv = the minimum detectable count rate in cpm that can be reliably detected by the "surveyor" d'= index of sensitivity, unit less (MARSSIM default value of 1.38 is assigned),
bi= background counts observed in the interval i, i= observation interval (s),
p = surveyor efficiency, unit less (MARSSIM default value of 0.5 is assigned),
MDCscan = the scan MDC, here in units of pCi/g, Conv = instrument response conversion factor, units of cpm per ftR/h, MS, = instrument response in units of jtR/h per pCi/g (determined empirically or with a shielding algorithm).
Site-specific parameter values for the MDCscan equation are obtained from the technical basis document [PBRF 2009a]. The most conservative instrument response conversion factor for detectors in the PBRF LMI 44-10 inventory is 232.39 cpm per 21 As discussed in the next section, the scan sensitivities of instruments used in the FSS of the SDPTSSE were below the DCGLw, and no increase in the number of measurements calculated using the Sign Test was required.
33
Plum Brook Reactor Facility FSSR, Rev. 1
ýtR/h for Cs-137 and 262.21 for Co-60. The instrument response factors for Cs-137 and Co-60 respectively are 0.138 and 0.667 jtR/h per pCi/g.
In accordance with the FSSP [NASA 2007], gamma scanning was performed over land surfaces to identify locations of residual surface activity. Nal gamma scintillation detectors (typically 2" x 2") were used for these scans. Scanning was generally performed by moving the detector in a serpentine pattern within 10 cm (4 in) from the surface, while advancing at a rate not to exceed 0.5 m (20 in) per second. Technicians responded to indications of elevated areas, both audible and visual, while surveying. Upon detecting an increase in visual or audible response, the technician reduced the scan speed or paused and isolated the elevated area. If the elevated activity was verified to exceed the established investigation level, the area was bounded (e.g., marked or flagged and measured to obtain an estimated affected surface area).
A summary of the a' priori detection sensitivities, for Ludlum model 44-10 (2" x 2" Nal detector) used to scan the open land survey units that constitute SDPTSSE is provided in Table 12. Measurement sensitivities provided in this section relate both to the gamma scan sensitivities and the static measurement sensitivities.
Table 12, Typical Detection Sensitivities of 44-10 for Co-60 and Cs-137 Co-60(')
Cs-137(4 *(5 )
Background
MDCR(2)
MDCscan MDCRW2)
MDCscan (4)
(cpm)
(ncpm)(3)
(pCi/g)
(ncpm)(3)
(pCi/g) 50 50.3 1.50 71.2 3.13 100 71.2 2.13 100.6 4.43 150 87.1 2.61 123.2 5.42 200 100.6 3.01 142.3 6.26 250 112.5 3.36 159.1 7.00 Table 12 Notes:
- 1. Per SR-39, the scan action level is 150 ncpm for Co-60. This value applies to survey units OL-I-10, OL-1-42, and OL-1-45.
- 2.
MDCR = Minimum Detectable Count Rate.
- 3. ncpm = net counts per minute=gross counts per minute - background counts per minute.
- 4.
Per SRs 30, 33, 37, and 44 the scan action level is 250 ncpm for Cs-137. This value applies to all remaining survey units contained within the SDPTSSE Attachment to the FSSR.
- 5. Per SR-46, the scan action level is 241 ncpm for Cs-137. This value applies to survey unit OL-1-26.
34
Plum Brook Reactor Facility FSSR, Rev. 1 5.0 Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Survey Results Results of the SDPTSSE FSS are presented in this section. This section includes scan survey frequencies (% of areas covered) for each survey unit and occurrence of events where scan investigation levels were exceeded. Investigations performed and the results are summarized. Soil sample results for each survey unit, along with comparison tests of survey unit maximum and average values with the DCGLw are provided. No statistical tests were required. It is shown that levels of residual contamination have been reduced to levels that are ALARA. Soil activity concentrations are compared to EPA trigger levels in accordance with the 2002 Memorandum of Understanding between the NRC and EPA [USEPA 2002].
This section closes with a summary which concludes that applicable criteria for release of the SDPTSSE for unrestricted use are satisfied and all FSS Plan requirements are met.
Additionally, Section 9.2 of the FSS plan states that measurements performed during characterization, turnover and investigation surveys can be used as FSS data if they are performed according to the same requirements as the final survey data. These requirements include:
(1) The survey data is representative of the as-left survey unit condition and is not impacted by further remediation; (2) The application of isolation measures to the survey unit to prevent re-contamination and to maintain final configuration; and (3) The data collection and design were in accordance with FSS methods (e.g.,
MDCscn, investigation levels, soil sample number and location, statistical tests, and EMC tests).
5.1 Surveys and Investigations 5.1.1 Scan Surveys Scan surveys were performed in accordance with the FSS requirements contained in the following Survey Requests:
" SR-164 (survey unit OL-I-1),
- SR-165 (survey unit OL-1-2),
- SR-169 (survey units OL-1-3 and OL-1-4),
" SR-176 (survey units OL-1-3 and OL-1-5),
" SR-204 (survey units OL-1-6),
" SR-237 (survey units OL-1-9, OL-I-1 1 through OL-1-25, OL-1-33 through OL-1-41, OL-1-43, and OL-1-44),
" SR-242 (survey units OL-1-9 through OL-1-25, and OL-1-33 through OL 45)
" SR-244 (survey units OL-I-10, OL-1-42, and OL-1-45),
" SR-277 (survey unit OL-1-26), and
" SR-279 (survey unit OL-1-26).
100% of all Class I survey units were scanned with the Ludlum 2350-1 with the 44-10 detector setup with a window for either Cs-137 or Co-60 energies. A scan action 35
Plum Brook Reactor Facility FSSR, Rev. I level of 250 ncpm, for Cs-137, was established, per the SR (Except for those survey units covered by SR-244 which provided a scan action level of 150 ncpm, (for Co-
- 60) and the survey unit covered by SR-277 (OL-1-26), which had an action level of 241 ncpm (for Cs-137). The scan action levels were determined by estimating a background count rate for the area and establishing an action level at a value less than the DCGL, typically 75% of the DCGL.
Static measurements were conducted at each location that exceeded the action level and judgmental soil samples were collected at the discretion of the FSS/Characterization Supervisor or Engineer.
Scan survey results were reviewed to confirm that the scan coverage requirement (as
% of survey unit area) was satisfied for all survey units. QC scans were reviewed and analyzed by the FSS/Characterization Engineer while processing survey unit release records. The results of QC replicate surveys were also reviewed to confirm that the minimum coverage requirement of 5% was satisfied. Results of the SDPTSSE scan surveys are compiled in Table 13. See Exhibits 7, 8 and 14 of Appendix A for a photograph of radiological surveys being conducted after SDS disassembly.
Table 13, Scan Survey Results CSurface Area Surface Area Surfe Area Surfe Area Scan QC Replicate Investigation Survey a
SR #
of Survey Unit of Survey Unit Survey Scan Coverage Level Unt sCoverage
(%) (2)
Exceeded Unit s
(in Square (in Square C%)
(2c s
Meters)
Feet)
OL-1-1 1
164 1323 14246 100 5.99 No OL-1-2 1
165 1834 19738 100 5.7 Yes(3 )
OL-1-3 1
169/176 1193 12843 100 5.5 Yes(3)
OL-1-4 1
169 1329 14306 100 7.0 NoM 3*
OL-1-5 1
176 190 2049 100 13.4 Yes"3' OL-1-6 1
204 1166 12548 100 7.1 No OL-1-7 1
237 801 8619 100 6.0 No OL-1-8 1
237 537 5777 100 7.8 No OL-1-9 1
237/242 1954 21036 100 5.7 No OL-1-10 1
244 221 2380 100 8.4 No OL-1-11 1
237/242 222 2385 100 6.3 No OL-1-12 1
237/242 1175 12647 100 6.3 No OL-1-13 1
237/242 1175 12653 100 7.6 No OL-1-14 1
237/242 1377 14818 100 7.5 No OL-1-15 1
237/242 1691 18199 100 5.8 No OL-1-16 1
237/242 1332 14333 100 7.5 No OL-1-17 1
237/242 805 8670 100 5.9 No OL-1-18 1
237/242 362 3900 100 15.4 No OL-1-19 1
237/242 202 2171 100 5.5 No OL-1-20 1
237/242 885 9527 100 6.3 No OL-1-21 1
237/242 895 9637 100 7.0 No OL-1-22 1
237/242 549 5912 100 30.4 No OL-1-23 1
237/242 255 2747 100 27.3 No OL-1-24 1
237/242 222 2386 100 6.7 No OL-1-25 1
237/242 956 10287 100 6.7 No 36
Plum Brook Reactor Facility FSSR, Rev. 1 Table 13, Scan Survey Results CSurface Area Surface Area I
of Survey Unit of Survey Unit Scan QC Replicate Investigation Survey a
SR #
Survey Scan Coverage Level Unt sCoverage
(%) (2)
Exceeded Unit s
(in Square (in Square
(%)
(2c s
Meters)
Feet)
OL-1-26 1
277/279 118 1268 100 6.3 No OL-1-33 1
237/242 93 998 100 5.0 No OL-1-34 1
237/242 61 660 100 5.3 No OL-1-35 1
237/242 77 827 100 5.4 No OL-1-36 1
237/242 97 1041 100 9.6 No OL-1-37 1
237/242 82 879 100 5.7 No OL-1-38 1
237/242 88 947 100 10.6 No OL-1-39 1
237/242 267 2877 100 7.0 No OL-1-40 1
237/242 74 796 100 21.1 No OL-1-41 1
237/242 151 1622 100 6.8 No OL-1-42 1 242/244 171 1844 100 5.4 No OL-1-43 1
237/242 518 5579 100 5.4 No OL-1-44 1
237/242 675 7268 100 5.2 No OL-1-45 1
242/244 146 1571 100 15.3 No Table 13 Notes:
- 1. The % scan coverage is given as the % of the area scanned in the initial survey. For Class I areas, 100% scan is required per Table 5-1 of the FSSP and Table 7 of this report.
- 2. Obtained from Survey Unit Release Records.
- 3. Refer to Section 5.1.2 of this report for an explanation of these survey unit investigation levels.
The results provided in Table 13 show that scan coverage requirements were satisfied for all survey units. Table 13 results also shows that scan investigation levels were exceeded in only 3 out of 39 survey units.
5.1.2 Investigative Measurements and Judgmental Soil Samples As identified in Table 13, three survey units (OL-1-2, OL-1-3 and OL-1-5) were documented to have investigative measurements or judgmental soil samples collected within their boundaries. A description of the additional surveys and sampling conducted in each of the four survey units is as follows:
Survey Unit OL-1-2 is located in the southern section of the protected area, north of Pentolite Road and East of Line 2 Road. During scanning of the survey unit, one area of elevated activity, > the scan investigation level, was identified in the far eastern portion of the survey unit. The area was identified as IM-1 and was approximately 1 ft2 of surface area. The scan indicated 322 ncpm at location IM-1. Surface (0-6") and sub-surface (6"-
12") sampling was performed at this location, under SR-165. The sample results indicated that the surface (0-6") soil sample contained measured Cs-137 activity of 4.22 pCi/g and no detectable Co-60 activity. The subsurface (6"-12") sample at location IM-1 indicated Cs-137 activity of 0.747 pCi/g and no detectable Co-60 activity. No further action was taken.
37
Plum Brook Reactor Facility FSSR, Rev. 1 Survey Unit OL-1-3 is located where the North Cold Retention Basin (CRB-
- 1) resided. This survey unit originally encompassed the North CRB and the area between the North and South CRBs.
However, elevated activity was identified on the area between the North and South CRBs. FSS performed under Survey Design #33 indicated that the Survey Unit needed additional remediation. Surveys confirmed that broken piping in the south side of survey unit OL-1-3 was contaminated with activity levels > 50,000 dpm/100 cm2, beta. All piping found was removed for disposal. Investigative surveys were performed after FSS was suspended on OL-1 3 and indicated that the area of elevated activity was limited to the ramp separating the North and South Retention Basins. Volumetric samples of the pipe scrapings/pieces yielded 622 pCi/g Cs-137 and 61 pCi/g Co-60. The area of elevated activity was separated from OL-1-3 and a new survey unit was created, OL-1-5.
Four additional samples were collected within OL-1-3 and identified as IM-1 through IM-4. The samples were collected from the bottom of the North CRB excavation. The reason for the samples being collected was because during scanning, there was some standing water present and the FSS Lead Engineer requested soil samples to ensure that the scan results were representative of the conditions present in the excavation. The results of the soil sampling indicated no detectable Cs-137 or Co-60 activity was present in any of the four samples.
Survey Unit OL-1-4 is located where the South Cold Retention Basin (CRB-
- 2) resided. Four additional samples were collected within OL-1-4 and identified as IM-1 through IM-4. The samples were collected from the bottom of the South CRB excavation. The reason for the samples being collected was because during scanning, there was some standing water present and the FSS Lead Engineer requested soil samples to ensure that the scan results were representative of the conditions present in the excavation.
The results of the soil sampling indicated no detectable Cs-137 or Co-60 activity was present in any of the four samples. No further action was taken.
Survey Unit OL-1-5 is located between where the North and South CRBs resided. There were three areas prompting investigations in survey unit OL-1-5:
o One area, that was 2.5' x 4', was located on the west side of OL-1-5 near a partially buried radioactive pipe. Three soil samples (SR-176-25 through SR-176-27) and three static measurements (IM-1 through IM-3) were obtained in this area.
o The average Cs-137 and Co-60 activity of the soil samples taken in this area was 24.9 pCi/gm Cs-137 and 4.9 pCi/gm Co-60. These average values are well below the calculated DCGLEMc based on an area factor of 10.4 as found in Table 4, and utilizing the following equation from Procedure CS-09, step 4.5.2 where:
38
Plum Brook Reactor Facility FSSR, Rev. 1 AFj= 10.4 DCGLw = 11.82 (Cs-137 DCGLSUR for Cs-137 and Sr-90)
DCGLEMC = 122.9.
DCGLEMc = AFj x DCGLw o
Compliance with soil DCGLEMC was determined using the gamma spectroscopy results for SR-176-25 through SR-176-27 and a unity rule calculation performed utilizing the following equation from CS-09, step 4.5.3 where:
Cs-137 = 24.9 pCi/gm Cs-137DCGLEMc= 122.9 pCi/gm
The product of this calculation (unity fraction) is 0.327 and is < 1.0.
o An elevated measurement test was performed utilizing the following equation from Procedure CS-09, Section 4.2 where:
8 = the average residual activity in the survey unit = 1.16 pCi/gm DCGLw = 11.55 (Cs-137 DCGLSUR for Cs-137, Sr-90 & Co-60) average concentration in the elevated area-S = 23.7 pCi/gm
" Area Factor = 10.4 9
+ (average concentration in elevated area -. 5) < 1.0 DCGLw (Area Factor)(DCGLw)
The result of this calculation is 0.29 and is < 1.0.
Since the calculated value is determined to be < 1.0, the area passes the EMC determination and no further action is required.
2 The other two elevated areas were both small in surface area, < 100 cm. The highest Cs-137 soil sample activity from these two elevated locations was 7.1 39
Plum Brook Reactor Facility FSSR, Rev. 1 pCi/g, which is < the DCGLW value (for Cs-137, and all Co-60 activities were < MDA. Therefore, no further actions were taken on these areas.
5.1.3 Systematic Soil Sampling 5.1.3.1 Soil Sampling for Class 1 Areas Systematic soil sampling was conducted within each of the 39 survey units that constitute the SDPTSSE in accordance with the FSSP [NASA 20071 and the applicable Survey Request.
Systematic soil samples were identified in each survey unit, by VSP, in accordance with procedure CS-08, Final Status Survey Design.
As stated in Table 4, the DCGLsuR for soil sampling is 11.82 pCi/g for Cs-137 and the DCGLw is 3.8 pCi/g for Co-60 in accordance with Survey Design #Ws 30, 33, 37, and 44. The DCGLw for soil sampling is 14.7 pCi/g for Cs-137 and the DCGLsUR is 3.5 pCi/g for Co-60 in accordance with Survey Design # 39. The DCGLsUR for soil sampling is 11.4 pCi/g for Cs-137 and the DCGLw is 3.7 pCi/g for Co-60 in accordance with Survey Design # 46. Compliance with the DCGL is demonstrated through the use of the unity rule. The results are as follows:
Four hundred and seventy-one (471) samples, including 40 QC samples, from 431 sample locations were processed and analyzed.
Of the 471 original samples collected and analyzed, 48 were > MDA for Cs-137 and 1 sample was >MDA for Co-60.
" The highest Cs-137 activity was in Survey Unit OL-1-25 at location Sample Point (SP)-2. The Cs-137 activity at this location was 8.80E-01 pCi/g +/- 2.22 E-01 pCi/g. The measured Co-60 activity at this location was <MDA. The highest Co-60 activity measured was in Survey Unit OL-1-4 at location SP-5.
The Co-60 activity at this location was and 1.00E+00 pCi/g + 1.76E-01 pCi/g. This is the, only sample result > the Co-60 MDA. The Cs-137 activity measured at this location was 5.83E-0l pCi/g + 1.76E-01 pCi/g.
- The average activity for all systematic soil samples, collected within Class I areas, was 1.06E-01 pCi/g for Cs-137 and 1.14E-01 pCi/g for Co-60.22 Refer to Table 14 of this report for a summary, by survey unit, of the average and maximum Cs-137 and Co-60 systematic soil sample results. Additionally, refer to Appendix B of this report for systematic soil sample locations, by survey unit. Also, refer to Appendix C of this report for all systematic soil sample results, by survey unit.
22 The average activity was determined by using the MDA value if the activity was determined by quantitative analysis to be at or below the MDA.
40
Plum Brook Reactor Facility FSSR, Rev. 1 5.1.3.2 Quality Control Sample Analysis The SRs required splitting 5% of samples for QC purposes. Forty (40) of the 431 samples, or 9.3 %, were split for QC analysis.
Forty Quality Control (QC) samples were collected and analyzed in Class 1 areas.
All 40 samples were analyzed and the results compared to the original sample results. The comparison was in accord with the method in the FSS Plan, Section 12.7.2 [NASA 2007]. In this method the sample resolution is calculated as the quotient of the original sample one-sigma uncertainty and the sample result. Then the ratios of QC to original sample results are compared to acceptance values specified for each range of resolution given in FSS Plan Table 12.2. The ratios were all within the acceptable range provided in Table 12.2. See Appendix C for QC Comparison results.
41
Plum Brook Reactor Facility FSSR, Rev. 1 Table 14, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Systematic Soil Sample Results By Survey Unit Cs-137, DCGLw = 11.82 pCi/g1)
Co-60, DCGLw = 3.80 pCi/gd1)
Maximum Test Average Test Maximum Test Average Test Result Average Tesult:
Result:
(pCi/g)
Result:
Average Survey No. of (pCi/g)
Maximum Average <
(pCi/g)
Maximum (2)
Average <
Unity Unit ID Measurements
< DCGLw DCGLw
< DCGLw DCGLW Fraction (2)
OL-1-1 11 0.162 Yes 0.060 Yes 0.076 Yes 0.060 Yes 0.021 OL-1-2 11 0.428 Yes 0.428 Yes 0.076 Yes 0.054 Yes 0.050 OL-1-3 11 0.190 Yes 0.077 Yes 0.134 Yes 0.119 Yes 0.038 OL-1-4 11 0.583 Yes 0.125 Yes 1.000 Yes 0.191 Yes 0.061 OL-1-5 11 0.303 Yes 0.100 Yes 0.129 Yes 0.114 Yes 0.039 OL-1-6 11 0.102 Yes 0.080 Yes 0.137 Yes 0.117 Yes 0.038 OL-1-7 11 0.112 Yes 0.070 Yes 0.128 Yes 0.104 Yes 0.033 OL-1-8 11 0.087 Yes 0.073 Yes 0.120 Yes 0.110 Yes 0.035 OL-1-9 11 0.112 Yes 0.077 Yes 0.141 Yes 0.120 Yes 0.038 OL-I-10W3) 11 0.205 Yes 0.085 Yes 0.136 Yes 0.116 Yes 0.039 OL-1-11 11 0.150 Yes 0.080 Yes 0.133 Yes 0.120 Yes 0.038 OL-1-12 12 0.179 Yes 0.085 Yes 0.138 Yes 0.115 Yes 0.038 OL-1-13 11 0.209 Yes 0.082 Yes 0.117 Yes 0.108 Yes 0.035 OL-1-14 11 0.275 Yes 0.115 Yes 0.139 Yes 0.118 Yes 0.041 OL-1-15 11 0.293 Yes 0.110 Yes 0.130 Yes 0.110 Yes 0.038 OL-1-16 11 0.369 Yes 0.113 Yes 0.122 Yes 0.113 Yes 0.039 OL-1-17 11 0.262 Yes 0.122 Yes 0.149 Yes 0.117 Yes 0.041 OL-1-18 11 0.111 Yes 0.076 Yes 0.131 Yes 0.114 Yes 0.037 OL-1-19 11 0.183 Yes 0.107 Yes 0.119 Yes 0.105 Yes 0.037 OL-1-20 11 0.092 Yes 0.077 Yes 0.145 Yes 0.122 Yes 0.039 OL-1-21 11 0.236 Yes 0.075 Yes 0.137 Yes 0.116 Yes 0.037 OL-1-22 11 0.116 Yes 0.085 Yes 0.143 Yes 0.128 Yes 0.041 OL-1-23 11 0.183 Yes 0.077 Yes 0.135 Yes 0.108 Yes 0.035 OL-1-24 11 0.295 Yes 0.095 Yes 0.125 Yes 0.118 Yes 0.039 42
Plum Brook Reactor Facility FSSR, Rev. 1 Table 14, Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Systematic Soil Sample Results By Survey Unit Cs-137, DCGLw = 11.82 pCi/gd)
Co-60, DCGLw = 3.80 pCi/g(')
Maximum Test est Maximum Test Average Test Survey No.moResult:
(pCi/g) (2)
Result:
Result:
(pCi/g)
Result:
Average Survey No. of (pCi/g)
Maximum Average <
(pCi/g)
Maximum (2)
Average <
Unity Unit ID Measurements
< DCGLw DCGLw
< DCGLw DCGLw Fraction (2)
OL-1-25 11 0.880 Yes 0.204 Yes 0.144 Yes 0.130 Yes 0.052 OL-1-26'4) 12 0.112 Yes 0.079 Yes 0.140 Yes 0.118 Yes 0.039 OL-1-33 11 0.167 Yes 0.084 Yes 0.136 Yes 0.115 Yes 0.037 OL-1-34 11 0.191 Yes 0.072 Yes 0.137 Yes 0.115 Yes 0.036 OL-1-35 11 0.159 Yes 0.088 Yes 0.146 Yes 0.123 Yes 0.040 OL-1-36 11 0.310 Yes 0.105 Yes 0.150 Yes 0.127 Yes 0.042 OL-1-37 11 0.130 Yes 0.089 Yes 0.143 Yes 0.116 Yes 0.039 OL-1-38 11 0.676 Yes 0.164 Yes 0.140 Yes 0.112 Yes 0.043 OL-1-39 11 0.271 Yes 0.124 Yes 0.137 Yes 0.124 Yes 0.043 OL-1-40 11 0.133 Yes 0.085 Yes 0.133 Yes 0.115 Yes 0.037 OL-1-41 11 0.126 Yes 0.091 Yes 0.146 Yes 0.117 Yes 0.039 OL-1-42(3 11 0.105 Yes 0.082 Yes 0.139 Yes 0.112 Yes 0.038 OL-1-43 11 0.392 Yes 0.112 Yes 0.129 Yes 0.106 Yes 0.037 OL-1-44 11 0.816 Yes 0.155 Yes 0.150 Yes 0.109 Yes 0.042 OL-1-45()
11 0.395 Yes 0.128 Yes 0.133 Yes 0.108 Yes 0.040 Total 431 Maximum 0.880 0.428 1.000 0.191 0.061 Grand Mean 0.106 0.114 0.039 Table 14 Notes:
1.
2.
3.
4.
The soil sample DCGLs for survey units covered by Survey Designs 30, 33, 37 and 44 was pCi/g for Co-60.
11.82 pCi/g for Cs-137 and 3.80 Calculation of average values and unity fractions substitution of MDA values in sample results reported as <MDA.
The soil sample DCGLs for survey units covered by Survey Design 39 was 3.50 pCi/g for Co-60 and 14.7 pCi/g for Cs-137.
The soil sample DCGLs for survey units covered by Survey Design 46 is 11.40 pCi/g for Cs-137 and 3.7 pCi/g for Co-60.
43
Plum Brook Reactor Facility FSSR, Rev. 1 5.2 ALARA Evaluation It is shown that residual contamination in the SDPTSSE has been reduced to levels that are ALARA, using a method acceptable to the NRC. The NRC guidance on determining that residual contamination levels are ALARA includes the following:
"In light of the conservatism in the building surface and surface soil generic screening levels developed by the NRC, NRC staff presumes, absent information to the contrary, those licensees who remediate building surfaces or soil to the generic screening levels do not need to provide analyses to demonstrate that these screening levels are ALARA. In addition, if residual radioactivity cannot be detected, it may be presumed that it had been reduced to levels that are ALARA. Therefore the licensee may not need to conduct an explicit analysis to meet the ALARA requirement." 23 Applicable NRC surface soil screening values are: Co-60, 3.8; Sr-90, 1.7 and Cs-137, 11 (all in pCi/g)24. From Appendix C, the highest Cs-137 activity was in Survey Unit OL-1-25 at location SP-2. The activity at this location was 8.80E-01 +/- 2.22E-01 pCi/g and <MDA for Co-
- 60. The highest Co-60 activity measured was in Survey Unit OL-1-4 at location SP-5. The activity at this location was 1.00E+00 +/- 1.76E-01 pCi/g. The Cs-137 activity at this location was 5.83E-01 +/- 1.76E-01 pCi/g. These values are well below the applicable NRC surface soil screening values stated above.
Since Cs-137 is the surrogate for Sr-90 and the Sr-90: Cs-137 activity ratio is only 0.081/0.912=0.08925, the activity concentration of Sr-90 is also well below the screening level.
The average activity for all systematic soil samples collected within all Class 1 areas, was 1.06E-01 pCi/g for Cs-137 and 1.14E-01 pCi/g for Co-60.Therefore, all soil sample results are below their respective screening level values. From these comparisons, it is concluded that the ALARA criterion is satisfied.
5.3 Comparison with EPA Trigger Levels The PBRF license termination process includes a review of residual contamination levels in groundwater and soil, as applicable, in accordance with the October 2002 Memorandum of Understanding (MOU) between the US NRC and the US Environmental Protection Agency (EPA) [USEPA 2002]. Concentrations of individual radionuclides, identified as "trigger levels" for further review and consultation between the agencies, are published in the MOU.
The trigger levels applicable to the PBRF for residual soil concentrations of the radionuclides of concern are:
23 This guidance was initially published in Draft Regulatory Guide DG-4006, but has been reissued in NUREG-1757 Volume 2[USNRC 2006].
24 Soil Screening Levels from NUREG-1757 Volume 2, Appendix H, Table H-2 [USNRC 2006].
25 The Sr-90:Cs-137 activity ratio for Survey Units OL-1-10, OL-1-42 and OL-1-45 is 0.085/0.201=0.423, per Survey Design 39 and Table 5-2 of the PBRF-TBD-09-001 [PBRF 2009].
44
Plum Brook Reactor Facility FSSR, Rev. 1
- Co-60, 4 pCi/g,
- Sr-90 (plus daughter activity), 23 pCi/g and
- Cs-137 (plus daughter activity), 6 pCi/g.
As reported in Section 5.1.3.1 above, the average and maximum activity values for all systematic soil samples collected are as follows:
1.06E-01 pCi/g (average value for Cs-137),
8.80E-01 pCi/g (maximum value for Cs-137),
1.14E-0 1 pCi/g (average value for Co-60), and 1.OOE+00 pCi/g (maximum value for Co-60).
Therefore, all systematic soil sample results are below the EPA Trigger Levels stated above.
Since Cs-137 is the surrogate for Sr-90 and the Sr-90: Cs-137 activity ratio is only 0.017, the activity concentration of Sr-90 is also well below the trigger level.
5.4 Conclusions The results presented above demonstrate that the SDPTSSE satisfies all FSS Plan commitments and meets the release criteria in 10CFR20 Subpart E. The principal conclusions are:
" Scan surveys were performed in all 39 survey units with scan coverage equal to (100%
for Class 1 areas) the percentage requirements stated in the FSSP.
- While standing water was present in the two CRB survey units (OL-1-3 & OL-1-4) during scanning activities, the presence of water in the survey units did not adversely impact the performance of required 100% scan surveys. Furthermore, additional sampling conducted within these survey units indicated that no detectable Cs-137 or Co-60 activity was present in the samples.
- Residual surface soil contamination above scan investigation levels was detected in only three survey units. Soil sample results indicated that the activity present was well below the DCGLw or DCGLEMC, as applicable (in one survey unit).
- All 431 systematic soil sample results were less than the applicable DCGLw values for.
- Forty (40) QC soil sample (split samples) results were less than the applicable DCGLW values for Cs-137 and Co-60.
- Residual surface activity and soil concentration measurement results are shown to be less than NRC screening level values - demonstrating that the ALARA criterion is satisfied.
- Residual activity concentrations measured in the soil survey units were compared to, and found to be less than EPA trigger levels.
" No changes in area classification from what was proposed in the FSS Plan were made and any area not identified in the FSS Plan was given a classification of 1.
45
Plum Brook Reactor Facility FSSR, Rev. 1 There were no changes from initial assumptions (in the FSS Plan) regarding the extent of residual activity in the SDPTSSE.
6.0 References Bowles 2006 Hagelin 2010 MWH 2005 MWH 2005a NACA 1956 NASA 1959 NASA 2006 NASA 2007 NASA 2007a NASA 2010 PBRF 2009 PBRF 2009a PBRF 2009b Mark D. Bowles, Science in Flux, NASA's Nuclear Program at Plum Brook station 1955 - 2005, The NASA History Series, June 2006.
Karl W. Hagelin, Bremba K. Jones and Associates, NASA Plum Brook Reactor Facility Coordinates, Personal Communication, December 20, 2010.
MWH Constructors, Soil Characterization Report, Plum Brook Reactor Facility, Feb. 14, 2005.
MWH Constructors, PBRF Decommissioning Project Memorandum from Bruce Mann to Greg Fiscus, Re: Guidance for Soil Remediation - Action Levels, February 24, 2005.
National Advisory Committee on Aeronautics, NACA Nuclear Reactor Plot Plan and Soil Boring Data, Drawing No. PFO00101, Plot Plan and Soil Boring Data, Dec.
4, 1956.
NASA, Final Hazards Summary Part II, Appendix D, Memorandum on the Geology and Hydrology of a Proposed Reactor site Near Sandusky, Ohio, 1959 NASA Safety and MissionAssurance Directorate, Plum Brook Reactor Facility, Decommissioning Project Quality Assurance Plan, QA-01, Revision 2, February 2006.
NASA Safety and Mission Assurance Directorate, Final Status Survey Plan for the Plum Brook Reactor Facility, Revision 1, February 2007.
NASA Safety and Mission Assurance Directorate, Decommissioning Plan for the Plum Brook Reactor Facility, Revision 6, July 2007.
NASA Glenn Mapping System, Plum Brook Station Reactor Area, Coordinates at Centerline Intersection of Line 2 Road and Pentolite Road, 12/16/2010.
Plum Brook Reactor Facility Technical Basis Document, Radionuclide Distributions and Adjusted DCGLsfor Site Soils, PBRF-TBD-09-001, June 2009.
Plum Brook Reactor Facility Technical Basis Document, 44-10 NalDetector MDCscan Values for Various Survey Conditions, PBRF-TBD-09-002, June 2009.
Plum Brook Reactor Facility, Memorandum to Project File, J. L. Crooks, Don Young, FSS Final Report Background Information - Storm Drain System (SDS),
December 15, 2009.
46
PNL 2010 SNL 1999 TELE 1987 USACE 2004 USEPA 2002 USNRC 1998 USNRC 2000 USNRC 2006 Plum Brook Reactor Facility FSSR, Rev. 1 Battelle Pacific Northwest Laboratories (PNL), Visual sample Plan, Version 5.9, 2010.
Sandia National Laboratories (SNL), for US Nuclear Regulatory Commission, Residual Radioactive Contamination From Decommissioning, Parameter Analysis, NUREG/CR-5512, Vol.3, Oct. 1999.
Teledyne Isotopes, An Evaluation of the Plum Brook Reactor Facility and Documentation of Existing Conditions, Prepared for NASA Lewis Research Center, December 1987.
US Army Corps of Engineers Louisville District, Hydrological Report Plum Brook Reactor Facility Sandusky, Ohio, November 17, 2004.
Memorandum of Understanding, US Environmental Protection Agency and US Nuclear Regulatory Commission, Consultation and Finality on Decommissioning and Decontamination of Contaminated Sites, October 9, 2002.
US Nuclear Regulatory Commission, Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions, NUREG-1507, June 1998.
US Nuclear Regulatory Commission, Multi-Agency Radiation Survey and Site Investigation Manual (M4RSSIM), NUREG-1575, Rev. 1, August 2000.
US Nuclear Regulatory Commission, Consolidated Decommissioning Guidance, Characterization, Survey and Determination of Radiological Criteria, NUREG 1757, Vol. 2, Rev. 1, September 2006.
7.0 Appendices Appendix A - Exhibits Appendix B - Survey Unit Maps and Tables Showing Measurement Locations Appendix C - Final Status Survey Soil Sample Results 47
Plum Brook Reactor Facility Final Status Survey Report Storm Drains, Pipe Trenches & Other Sub-Surface Excavations Revision 0 Appendix A Exhibits
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 2 of 22 List of Exhibits Exhibit 1, Storm Drain, Pipe Trenches & Other Sub-Surface Excavations Survey Unit Breakdown... 3 Exhibit 2, Storm Drain System Laterals............................................................................................
4 Exhibit 3, Sanitary System Piping Location Map.............................................................................
5 Exhibit 4, Excavation of SDS Piping in Phase 4................................................................................
6 Exhibit 5, Excavation of SDS Piping in Phase 4................................................................................
7 Exhibit 6, Phase 6 of SDS Dismantlement........................................................................................
8 Exhibit 7, Phase 7 of SDS Dismantlement........................................................................................
9 Exhibit 8, Radiological Survey of Storm Drain Trenching..................................................................
10 Exhibit 9, Excavation of SDS Piping...................................................................................................
11 Exhibit 10, CRB Dismantlement......................................................................................................
12 Exhibit 11, CRB Disassembly...........................................................................................................
13 Exhibit 12, CRB Excavations...............................................................................................................
14 Exhibit 13, Excavations of Piping.........................................................
............................................... 15 Exhibit 14, Excavation South of WHB.................................
I.........................................................
16 Exhibit 15, Spill Area Excavation...................................................................................................
17 Exhibit 16, Lateral "A" Disassembly..................................................
...................................... 18 Exhibit 17, Hot Lab Drain Line Excavation......................................
19 Exhibit 18, Backfill after SDS Disassembly..................................................................................
20 Exhibit 19, Excavation of RCRA Soil...........................................................................................
21 Exhibit 20, Soil Staging.......................................................................................................................
22
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 3 of 22 Exhibit 1, Storm Drain, Pipe Trenches & Other Sub-Surface Excavations Survey Unit Breakdown UOL 1 -5 "0.1.- I I2 01.-
1.39
=>
OL-1-37 A
-OL-I-
17 12 AL IQ.r
~T~
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 4 of 22 Exhibit 2, Storm Drain System Laterals waam p~~rn I~.
C-
'-7;, i (I)---
a.--
76-J!
M1 r,-
w w
j I
,/
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 5 of 22 Exhibit 3, Sanitary System Piping Location Map
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 6 of 22 Exhibit 4, Excavation of SDS Piping in Phase 4 SDS West of CRB and East of Line 3 Road N
,,,, A'-.w SDS piping removal
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 7 of 22 Exhibit 5, Excavation of SDS Piping in Phase 4 Excavation of Lateral "D" South and West of CRB-2
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 8 of 22 Exhibit 6, Phase 6 of SDS Dismantlement X
A!
I
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 9 of 22 Exhibit 7, Phase 7 of SDS Dismantlement
.Q1"5Q 1vr,,ontinn Mnrth nf Panfnlifim PnneI Radiological Survey of
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 10 of 22 Exhibit 8, Radiological Survey of Storm Drain Trenching tted Inside Protected Area Fence near Intersection of Pentolite and Line 2 Roads "T
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 11 of 22 Exhibit 9, Excavation of SDS Piping SDS piping located west of ERB m
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Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 12 of 22 Exhibit 10, CRB Dismantlement Removal of Roof Structure on North C
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 13 of 22 Exhibit 11, CRB Disassembly Contaminated CRB Piping Removal Excavation of North CRB
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 14 of 22 Exhibit 12, CRB Excavations North and South Excavations M
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 15 of 22 Exhibit 13, Excavations of Piping Pipe # FH-103 and Sleeve from West Wall of WHB
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 16 of 22 Exhibit 14, Excavation South of WHB Concrete Pad Removal
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 17 of 22 Exhibit 15, Spill Area Excavation Concrete Pad South of WHB and West of Line 3 Road LoaW-out or Material
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 18 of 22 Exhibit 16, Lateral "A" Disassembly Excavation of SDS Piping
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 19 of 22 Exhibit 17, Hot Lab Drain Line Excavation West of Hot Lab and South of Reactor Security Building
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 20 of 22 Exhibit 18, Backfill after SDS Disassembly Lateral "A" Laterai AN LOOKiflg Trom
Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 21 of 22 Exhibit 19, Excavation of RCRA Soil
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Plum Brook Reactor Facility FSSR, Attachment 7 Appendix A Rev.0, Page 22 of 22 Exhibit 20, Soil Staging RCRA Area Soil being staged Soil from SDS Excavations