ML120370461

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Theodore Smith Ltr Revised Final Report No. 1: Independent Confirmatory Survey Summary and Results for the Enrico Fermi Atomic Power Plant, Unit 1, Newport, Michigan
ML120370461
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 01/30/2012
From: Harpenau E
Oak Ridge Institute for Science & Education
To: Tanya Smith
NRC/FSME/DWMEP/DURLD/RDB
References
DCN 2018-SR-01-1, RFTA 10-004
Download: ML120370461 (53)
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Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR THE ENRICO FERMI ATOMIC POWER PLANT, UNIT I NEWPORT, MICHIGAN Prepared by E. M. Harpenau Independent Environmental Assessment and Verification Program Oak Ridge Institute for Science and Education Oak Ridge, Tennessee 37831-0017 Prepared for the U.S. Nuclear Regulatory Commission FINAL REPORT JANUARY 2012 Prepared by the Oak Ridge Institute for Science and Education, under interagency agreement (NRC FIN No. F1008) between the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy. The Oak Ridge Institute for Science and Education performs complementary work under contract number DE-AC05-06OR23100 with the U.S. Department of Energy.

Enrico Fermi Atomic Power Plant, Unit 1 ii 2018-SR-01-1 TABLE OF CONTENTS PAGE LIST OF FIGURES......................................................................................................................................... iv LIST OF TABLES............................................................................................................................................ v ABBREVIATIONS AND ACRONYMS.................................................................................................... vi

1.0 INTRODUCTION

.................................................................................................................................... 1 2.0 SITE DESCRIPTION............................................................................................................................... 1 3.0 OBJECTIVES............................................................................................................................................. 2 4.0 DOCUMENT REVIEW........................................................................................................................... 2 5.0 PROCEDURES.......................................................................................................................................... 2 5.1 REFERENCE SYSTEM......................................................................................................................... 3 5.2 SURFACE SCANS................................................................................................................................. 3 5.2.1 Interior Survey Units................................................................................................................ 4 5.2.2 Exterior Survey Areas.............................................................................................................. 4 5.3 SURFACE ACTIVITY MEASUREMENTS............................................................................................. 4 5.4 SOIL AND MISCELLANEOUS MATERIAL SAMPLING...................................................................... 5 5.5 SURFACE ACTIVITY DATA COMPARISON....................................................................................... 5 6.0 SAMPLE ANALYSIS AND DATA INTERPRETATION.............................................................. 5 7.0 APPLICABLE SITE GUIDELINES..................................................................................................... 5 8.0 FINDINGS AND RESULTS.................................................................................................................. 6 8.1 DOCUMENT REVIEW......................................................................................................................... 6 8.2 SURFACE SCANS................................................................................................................................. 7 8.2.1 Interior Survey Units................................................................................................................ 7 8.2.2 Exterior Grounds and Roofs.................................................................................................. 7 8.3 SURFACE ACTIVITY MEASUREMENTS............................................................................................. 8 8.4 SURFACE ACTIVITY DATA COMPARISON....................................................................................... 8 8.5 RADIONUCLIDE CONCENTRATIONS IN SOIL AND ROOF SAMPLES........................................... 9 9.0 COMPARISON OF RESULTS WITH GUIDELINES..................................................................... 9 10.0

SUMMARY

................................................................................................................................................ 9

11.0 REFERENCES

....................................................................................................................................... 11 APPENDIX A FIGURES APPENDIX B TABLES

Enrico Fermi Atomic Power Plant, Unit 1 iii 2018-SR-01-1 TABLE OF CONTENTS (cont.)

PAGE APPENDIX C MAJOR INSTRUMENTATION C.1 SCANNING AND MEASUREMENT INSTRUMENT/DETECTOR COMBINATIONS.................... C-1 C.1.1 Gamma.................................................................................................................................. C-1 C.1.2 Alpha and Alpha Plus Beta................................................................................................. C-1 C.2 LABORATORY ANALYTICAL INSTRUMENTATION.................................................................... C-1 APPENDIX D SURVEY AND ANALYTICAL PROCEDURES D.1 PROJECT HEALTH AND SAFETY................................................................................................. D-1 D.2 CALIBRATION AND QUALITY ASSURANCE................................................................................ D-1 D.3 SURVEY PROCEDURES.................................................................................................................. D-2 D.3.1 Surface Scans........................................................................................................................ D-2 D.3.2 Surface Activity Measurements.......................................................................................... D-2 D.3.3 Soil Sampling........................................................................................................................ D-3 D.4 RADIOLOGICAL ANALYSIS.......................................................................................................... D-3 D.4.1 Gamma Spectroscopy......................................................................................................... D-3 D.5 DETECTION LIMITS...................................................................................................................... D-4

Enrico Fermi Atomic Power Plant, Unit 1 iv 2018-SR-01-1 LIST OF FIGURES PAGE Figure A-1: Location of the Detroit Edison Enrico Fermi Atomic Power Plant, Units 1 and 2........................................................................................................................................... A-1 Figure A-2: Enrico Fermi Atomic Power Plant, Unit 1 Plot Plan......................................................... A-2 Figure A-3: Turbine Building, Fourth FloorAlpha plus Beta Radiation Floor Scans.................... A-3 Figure A-4: Turbine Building, Fifth FloorAlpha plus Beta Radiation Floor Scans........................ A-4 Figure A-5: Turbine Building, Sixth FloorAlpha plus Beta Radiation Floor Scans........................ A-5 Figure A-6: Steam Generator Building, Upper LevelAlpha plus Beta Radiation Floor Scans.............................................................................................................................................. A-6 Figure A-7: Steam Generator Building, BasementAlpha plus Beta Radiation Floor Scans.......... A-7 Figure A-8: Fermi 1External Gamma Radiation Scans of Open Land Areas................................. A-8 Figure A-9: Turbine Building, Fifth Floor RoofExterior Gamma Radiation Scans....................... A-9 Figure A-10: Turbine Building, Seventh Floor RoofExterior Gamma Radiation Scans............. A-10 Figure A-11: Turbine Building, Fourth FloorAlpha plus Beta Direct Measurement Locations...................................................................................................................... A-11 Figure A-12: Turbine Building, Fifth FloorAlpha plus Beta Direct Measurement Locations...................................................................................................................... A-12 Figure A-13: Turbine Building, Sixth FloorAlpha plus Beta Direct Measurement Locations...................................................................................................................... A-13 Figure A-14: Steam Generator Building, Upper LevelAlpha plus Beta Direct Measurement Locations...................................................................................................................... A-14 Figure A-15: East Sodium GalleryAlpha plus Beta Direct Measurement Locations................... A-15 Figure A-16: Waste Gas BuildingAlpha plus Beta Direct Measurement Locations..................... A-16 Figure A-17: West Sodium GalleryAlpha plus Beta Direct Measurement Locations.................. A-17 Figure A-18: Fermi 1Exterior Soil and Turbine Roof Samples....................................................... A-18

Enrico Fermi Atomic Power Plant, Unit 1 v

2018-SR-01-1 LIST OF TABLES PAGE Table 1: Confirmatory Structural Survey Units............................................................................................. 4 Table 2: Surface Activity Range Summary..................................................................................................... 8 Table B-1: Surface Activity and Soil Concentration DCGLs..................................................................B-1 Table B-2: ESG01-01comparative Direct Measurement Results...........................................................B-2 Table B-3: Fermi 1 Radionuclide Surface Activity Levels.......................................................................B-3 Table B-4: Fermi 1 Radionuclide Concentrations for Activation and Fission Products in Soil and Building Media (pCi/g).......................................................................................................B-5 Table D-1: MDC Derived from Total Absorption Peak....................................................................... D-4

Enrico Fermi Atomic Power Plant, Unit 1 vi 2018-SR-01-1 ABBREVIATIONS AND ACRONYMS AEC Atomic Energy Commission cm centimeter cpm counts per minute DCGLW derived concentration guideline level DCGLGA gross activity derived concentration guideline level DOE U.S. Department of Energy DTE DTE Energy dpm disintegrations per minute ESG East Sodium Gallery Fermi 1 Enrico Fermi Atomic Power Plant, Unit 1 Fermi 2 Enrico Fermi Atomic Power Plant, Unit 2 FSS final status survey FSSP Final Status Survey Package FSSR Final Status Survey Report gal gallon GPS global positioning system IEAV Independent Environmental Assessment and Verification Program ITP Intercomparison Testing Program kg kilogram MAPEP Mixed Analyte Performance Evaluation Program MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDC Minimum Detectable Concentration MeV million electron volts m2 square meter MW megawatt mrem millirem NAD North American Datum NaI sodium iodide NIST National Institute of Standards and Technology NRC U.S. Nuclear Regulatory Commission NRIP NIST Radiochemistry Intercomparison Program ORAU Oak Ridge Associated Universities ORISE Oak Ridge Institute for Science and Education pCi/g picocuries per gram PRDC Power Reactor Development Company

Enrico Fermi Atomic Power Plant, Unit 1 vii 2018-SR-01-1 ABBREVIATIONS AND ACRONYMS (cont.)

ROC Radionuclide of Concern SGB Steam Generator Building TAP Total Absorption Peak TBN Turbine Building WGB Waste Gas Building WSG West Sodium Gallery yr year

Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR THE ENRICO FERMI ATOMIC POWER PLANT, UNIT I NEWPORT, MICHIGAN

1.0 INTRODUCTION

Enrico Fermi Atomic Power Plant, Unit 1 (Fermi 1) was a fast breeder reactor design that was cooled by sodium and operated at essentially atmospheric pressure. On May 10, 1963, the Atomic Energy Commission (AEC) granted an operating license, DPR-9, to the Power Reactor Development Company (PRDC), a consortium specifically formed to own and operate a nuclear reactor at the Fermi 1 site. The reactor was designed for a maximum capability of 430 megawatts (MW); however, the maximum reactor power with the first core loading (Core A) was 200 MW. The primary system was filled with sodium in December 1960 and criticality was achieved in August 1963.

The reactor was tested at low power during the first couple years of operation. Power ascension testing above 1 MW commenced in December 1965 immediately following the receipt of a high-power operating license. In October 1966, during power ascension, zirconium plates at the bottom of the reactor vessel became loose and blocked sodium coolant flow to some fuel subassemblies. Two subassemblies started to melt and the reactor was manually shut down. No abnormal releases to the environment occurred. Forty-two months later; after the cause had been determined, cleanup completed, and the fuel replaced, Fermi 1 was restarted. However, in November 1972, PRDC made the decision to decommission Fermi 1 as the core was approaching its burn-up limit. The fuel and blanket subassemblies were shipped off-site in 1973. Following that, the secondary sodium system was drained and sent off-site. The radioactive primary sodium was stored on-site in storage tanks and 55 gallon (gal) drums until it was shipped off-site in 1984. The initial decommissioning of Fermi 1 was completed in 1975. Effective January 23, 1976, DPR-9 was transferred to the DTE as a possession only license (DTE 2009).

2.0 SITE DESCRIPTION Fermi 1 is located in Monroe County near the town of Newport, Michigan on the western bank of Lake Erie (Figures A-1 and A-2). Fermi 1 and Enrico Fermi Atomic Power Plant, Unit 2 (Fermi 2) are located in the same controlled area on the same site. Fermi 1, however, stands beyond the

Enrico Fermi Atomic Power Plant, Unit 1 2

2018-SR-01-1 protected operational area of Fermi 2. The Fermi 1 License Termination boundary is made up of 27,200 square meters (m2) including roads, a railroad spur, buildings and land areas; a portion of which is occupied by an oily waste bin (DTE 2009). Figure A-2 shows the plot plan and associated building identifications.

3.0 OBJECTIVES The objectives of the confirmatory surveys were to provide independent contractor field data reviews and to generate independent radiological data for use by the U. S. Nuclear Regulatory Commission (NRC) in evaluating the accuracy and adequacy of the licensees procedures and Final Status Survey (FSS) results.

4.0 DOCUMENT REVIEW Prior to on-site activities, the Oak Ridge Institute for Science and Education (ORISE) was tasked with reviewing the Enrico Fermi Atomic Power Plant, Unit 1 Final Status Survey Report (FSSR) and the Final Status Survey Package (FSSP) in DTEs Fermi 1 License Termination Plan (LTP). The FSSP was specifically reviewed to identify the sites Radionuclides of Concern (ROC)s and the associated derived concentration guideline levels (DCGLW), ORISE also reviewed the licensees survey design and data quality objectives, instrumentation and calibration, and survey measurement methods to be used during the FSS (DTE 2009). All documents and data were reviewed for adequacy and appropriateness taking into account the LTP and Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) guidance (DTE 2009 and NRC 2000).

5.0 PROCEDURES The ORISE survey team visited the Fermi 1 site from July 12 through 15, 2010, to perform visual inspections, confirmatory measurements and sample collection along with side-by-side measurement comparisons of the ongoing decommissioning activities. The confirmatory survey activities were conducted in accordance with a site-specific plan, the ORISE/(Independent Environmental Assessment and Verification) IEAV Survey Procedures Manual and Quality Program Manual (ORISE 2010a, ORISE 2008 and ORAU 2009).

Survey units are classified based on contamination potential, as either Class 1, 2, or 3 in accordance with MARSSIM (NRC 2000). A description of each is as follows:

Enrico Fermi Atomic Power Plant, Unit 1 3

2018-SR-01-1 Class 1: Buildings or land areas that have a significant potential for radioactive contamination (based on site operating history) or known contamination (based on previous radiological surveys) that exceeds the expected DCGLW value.

Class 2: Buildings or land areas, often contiguous to Class 1 areas that have a potential for radioactive contamination but at levels less than the expected DCGLW.

Class 3: Remaining impacted buildings and land areas that are not expected to contain residual contamination, or are expected to contain levels of residual contamination at a small fraction of the DCGLW.

Confirmatory surveys were conducted in the Class 3 Turbine Building (TBN), Class 3 Steam Generator Building (SGB), Class 2 West Sodium Gallery (WSG), Class 2 Waste Gas Building (WGB), and the open land areas within the Fermi 1 footprint. An in-process inspection was conducted in the Class 2 East Sodium Gallery (ESG). Table 1, provides the list of structures, their associated survey unit identifications and the scan coverage of accessible surfaces each received when the survey units were evaluated.

5.1 REFERENCE SYSTEM Indoor measurements and sampling locations were referenced to prominent site features and documented on site drawings provided by the licensee. Exterior survey results and sample locations were referenced to prominent site features and/or Global Positioning System (GPS) coordinates.

The coordinate reference system used for the confirmatory survey was: North American Datum (NAD) 1983 UTM Zone 17N with units represented in meters.

5.2 SURFACE SCANS The licensees FSS results were considered when determining the level of confirmatory survey effort required to adequately represent each survey unit. Interior scans covered floors, lower walls, and accessible upper surfaces while exterior scans focused on soil areas. The surface scan coverage of the areas selected for confirmatory surveys varied based on the size and accessibility of the areas. The total area covered was dependent upon the results as the survey progressed. Scans were focused in areas with the highest potential for contamination (i.e. cracks and joints in the floor and walls, other horizontal surfaces, surface run-off pathways, etc.).

Enrico Fermi Atomic Power Plant, Unit 1 4

2018-SR-01-1 TABLE 1: CONFIRMATORY STRUCTURAL SURVEY UNITS STRUCTURE SURVEY UNIT ID SCAN COVERAGE Surface Alpha + Beta Gamma Turbine Building TBN01-04 Floor High Density High Density Lower Walls High Density High Density Steam Generator Building SGB01-01 Floor High Density High Density Lower Walls Low Density No Scan West Sodium Gallery WSG01-01 Floor Medium Density High Density Lower Walls Medium Density Medium Density Waste Gas Building WGB01-01 Floor Medium Density High Density Lower Walls Medium Density Medium Density East Sodium Gallery ESG01-01 Floor Medium Density High Density Lower Walls Medium Density High Density 5.2.1 Interior Survey Units Interior survey unit surfaces, including floors, lower walls, and other accessible surfaces were scanned using either large-area or hand-held gas proportional detectors for direct alpha and alpha plus beta radiation and for gamma radiation using a sodium iodide (NaI) detector. All detectors were coupled to ratemeter-scalers with audible indicators. Additionally, the large-area gas proportional detector was interfaced with a robotic total station which also enabled position and count rate data capture for floor surface scans in the nonconfined space survey units. Figures A-3 through A-7 show the interior (floor only) scan coverage.

5.2.2 Exterior Survey Areas Medium density gamma scans of the Fermi 1 footprint land areas and three building roofs were performed using NaI scintillation detectors for direct gamma radiation. Detectors were coupled to ratemeter-scalers with audible indicators. NaI detectors were coupled to a GPS unit that enabled real-time recording of both position and gamma count rates in one-second intervals. Figures A-8 through A-10 show the exterior gamma scan results for the land areas and roofs.

5.3 SURFACE ACTIVITY MEASUREMENTS Direct measurements to quantify total alpha and/or alpha plus beta activities on interior survey units were performed at selected licensee final status survey locations, judgmental locations, and locations where elevated direct radiation was detected by scans. Those measurements were collected using gas proportional detectors coupled with ratemeter-scalers. Questions and concerns were brought to the

Enrico Fermi Atomic Power Plant, Unit 1 5

2018-SR-01-1 immediate attention of the NRC representatives, the licensee, and are also noted in the Findings and Results section of this report. Figures A-11 through A-17 show the surface activity measurements.

5.4 SOIL AND MISCELLANEOUS MATERIAL SAMPLING One surface soil sample was collected from the exterior land areas. Two samples of miscellaneous roofing materials, consisting of the tar and gravel build-up, were collected from rooftops of the TBNs fourth and seventh floors. Selected sample locations were based on the results of gamma scans and probable migration/run-off collection pathways. Figure A-18 shows the sampled locations.

5.5 SURFACE ACTIVITY DATA COMPARISON ORISE performed side-by-side direct alpha plus beta measurements at six locations together with DTE FSS personnel to enable direct data comparison. These measurements were performed in survey unit ESG01-01.

6.0 SAMPLE ANALYSIS AND DATA INTERPRETATION Samples were returned to the ORISE laboratory in Oak Ridge, Tennessee for analysis and interpretation. Sample analyses were performed in accordance with the ORISE Laboratory Procedures Manual (ORISE 2010b). Soil and miscellaneous roofing material samples were analyzed by solid-state gamma spectroscopy for gamma-emitting ROCs. Analytical results were reported in units of picocuries per gram (pCi/g). Direct measurement data were converted to units of disintegrations per minute per 100 square centimeters (dpm/100 cm2). The data generated were compared with the approved DCGLWs established for the Fermi 1 site.

7.0 APPLICABLE SITE GUIDELINES The primary ROCs at the Fermi 1 site are beta-gamma emittersfission and activation products resulting from reactor operation. The building surface and soil DCGLW values are listed below. The DCGLW values were compared with the FSS measurements to determine compliance with the 25 millirem per year (mrem/yr) unrestricted use criterion. The average residual radioactivity above background must be less than or equal to the DCGLW. Table B-1 provides both the surface activity and soil concentration DCGLs.

Enrico Fermi Atomic Power Plant, Unit 1 6

2018-SR-01-1 During site characterization activities the licensee determined the specific ROCs for the site. The licensee determined the presence of multiple radionulcides by analyzing concrete cores, smears, and other sample media. These data were used in developing the final status survey package for gross activity DCGLGA (DTE 2009).

The gross activity DCGLGA values were calculated using the following equation:

=

1 1

1 +

2 2 +

Where: DCGLGA = gross activity DCGL fn = fraction of the total activity contributed by radionuclide n, and DCGLn = DCGL for radionuclide n.

8.0 FINDINGS AND RESULTS The results for each of the verification activities are discussed below.

8.1 DOCUMENT REVIEW The ORISE reviews of DTEs project documentation indicated that all procedures and methods implemented for the FSSs were appropriate and that the resultant data were acceptable. After review of the FSS data packages provided by the licensee, it was determined that they accurately and adequately explained the sequence of FSS activities at Fermi 1. Other observations made during the confirmatory survey site visit are described below.

During further review of the FSSP and the data submitted for the in-process, side-by-side measurement comparison in the ESG, an inconsistency was identified. The FSS instruction package stated cobalt-60 as the only ROC. DTEs total efficiency calculation used a source efficiency of 0.5 rather than 0.25. DTE provided the NSEF-10-0027 Fermi 1 Final Status Survey DCGL Selection for Survey Units and ESG_01_All FSS Data documents which describe how a weighted surface efficiency factor for cobalt-60, cesium-137, and strontium-90 and an instrument standoff factor were applied to the calculations to correct the observed direct measurement inconsistency (DTE 2010 and 2012). ORISE used the new radionuclide fraction information to calculate corresponding weighted efficiency and recalculated direct measurement surface activities.

Enrico Fermi Atomic Power Plant, Unit 1 7

2018-SR-01-1 During the second ORISE site visit, comparison measurements were collected using three ORISE and one DTE calibration sources to ensure that the issue had been resolved. A non-conservative bias was again exhibited when the data were reviewed. Further review of DTEs calibration certificates identified that they were using the 4 emission information from the calibration sheet as opposed to ORISE using the 2 emission rate. DTE project documentation indicated that survey activities were being conducted under the guidance of MARSSIM which recommends the use of a 2 emission rate instead of 4 (ORISE 2011). Using the appropriate parameters, DTE recalculated all surface activity measurements to date. The surface activity calculation incorporating the weighted efficiency and emission rate corrections is described in Section 8.4 8.2 SURFACE SCANS Surface scan results for the interior and exterior investigated areas are discussed below.

8.2.1 Interior Survey Units Surface scans of the selected areas within the TBN01-04, SGB01-01, WGB01-01, WSG01-01 and ESG01-01 did not identify radiation levels distinguishable from background. Scan surveys in the basement of the WGB01-01 identified elevated beta and gamma direct radiation from the south wall near the southwest corner of the room. ORISE performed a detailed survey of the elevated areas and identified four remaining pipes that had been disconnected and capped with red tape as the source of residual activity. The elevated beta and gamma radioactivity noted, which were at levels three times greater than background for that room, was associated with the capped end of the pipes.

The elevated activity was documented on the applicable survey map, was brought to the attention of the attending NRC and Fermi 1 staff, and discussed in the end of the day meeting on July 14, 2010.

Figures A-3 through A-7 show the floor scan data for several of the confirmatory survey units accessible with the robotic total station.

8.2.2 Exterior Grounds and Roofs Exterior open land scans performed with a NaI scintillation detector coupled with a ratemeter-scaler were at or less than two times background for areas on the south and southwest sides of Fermi 1. As scans progressed toward the Fermi 2 reactor, located north of Fermi 1, the gamma scan count rates increased to levels in excess of four times the typical instrument site background. Similar results were identified for the seventh floor TBN roof survey. It was determined that the gamma radiation

Enrico Fermi Atomic Power Plant, Unit 1 8

2018-SR-01-1 shine from the Fermi 2 reactor caused the observed elevated direct gamma radiation. Figure A-8 shows the gamma scan coverage and the gamma radiation count rates for the Fermi 1 open land areas.

8.3 SURFACE ACTIVITY MEASUREMENTS Total surface activity levels are provided in Table B-3. The reported surface activities represent gross levels that have not had background contributions subtracted, per the DTE FSS data reporting procedure. Table 2 provides a summary of the confirmatory measurement data for each survey unit.

TABLE 2: SURFACE ACTIVITY RANGE

SUMMARY

SURVEY UNIT ID Alpha (dpm/100 cm2)

Beta (dpm/100 cm2)

TBN01-04 9 to 53 790 to 1,500 SGB01-01 18 to 53 1,100 to 1,600 WSG01-01 NAa 570 to 700 WGB01-01 NAa 990 to 1,600 ESG01-01 NAa 1,000 to 1,300 aMeasurements were not collected for corresponding survey unit.

8.4 SURFACE ACTIVITY DATA COMPARISON The in-process side-by-side measurements ORISE collected in conjunction with DTEs FSS for the survey unit ESG01-01 are provided in Table B-2. The instrument/detector combinations used were:

  • ORISELudlum Model 2221 ratemeter-scaler coupled to a Ludlum Model 43-68 gas proportional detector
  • DTEModel 2350-1 data-logger coupled to a Ludlum Model 43-68 detector. DTE also used an acrylic spacer that provided a onecm stand-off from the surface being surveyed The total efficiencies for the instrument and detector combinations were 0.12 for DTE and 0.21 for ORISE. Prior to receiving the NSEF-10-0027 Fermi 1 Final Status Survey DCGL Selection for Survey Units document, there was a systematic non-conservative bias between the reported results where DTEs results were consistently reported an average of 40 percent below the ORISE result (DTE 2010). This document illustrates how DTE applied a weighted surface efficiency factor of 0.4379 accounting for radionuclide fractions and their respective surface efficiencies. The complete DTE total weighted efficiency calculation was:

Enrico Fermi Atomic Power Plant, Unit 1 9

2018-SR-01-1

= 0.3904 0.701 0.4379 Where 0.3904 = 2 instrument efficiency; 0.701 = 2 correction for instrument stand-off from surface; 0.4379 = weighted surface efficiency (DTE 2012). With the appropriate efficiencies, these comparative measurements were re-evaluated. The results are shown in Table B-2. The DTE:ORISE ratio averaged 0.86, an acceptable and conservative systematic bias.

8.5 RADIONUCLIDE CONCENTRATIONS IN SOIL AND ROOF SAMPLES Individual sample results for the gamma-emitting fission/activation products that DTE has identified as site-related contaminants are presented in Table B-4. Sample 2018M0001 had a cesium-137 concentration of 1.78 pCi/gabove typical background concentrations of less than 1 pCi/g. The sample was collected from a low spot where natural accumulation may have occurred due to surface run off. Additional investigations are recommended once FSS activities of the exterior survey units commence. Roof samples did not indicate the presence of any elevated concentrations of site-related contaminants.

9.0 COMPARISON OF RESULTS WITH GUIDELINES The total surface activity values were directly compared with the survey unit-specific gross activity DCGLGA values developed by the licensee. All values were less than the corresponding DCGLGA.

Laboratory analysis of the soil, tar, and gravel were less than 10% of the respective DCGLW values.

10.0

SUMMARY

At the request of the NRC, ORISE conducted confirmatory surveys of the Fermi 1 facility during the period of July 12 through 15, 2010. The survey activities included visual inspections and measurement and sampling activities. Confirmatory activities also included the review and assessment of the licensees project documentation and methodologies.

The licensee was forthcoming with information regarding the direct measurement variations identified during the in-process, side-by-side survey of the ESG. DTE resolved the surface activity discrepancy between ORISE and DTE. DTE provided to ORISE a revised survey plan, the NSEF-10-0027 Fermi 1 Final Status Survey DCGL Selection for Survey Units document, and the ESG_01_All FSS Data spreadsheet (DTE 2010 and 2012). These documents revised the radionuclide fractions, and the corresponding efficiencies, within the confirmatory survey units

Enrico Fermi Atomic Power Plant, Unit 1 10 2018-SR-01-1 evaluated. The beta surface activity range in Table 2; DTE and ORISE activities and ratios in Table B-2; and the alpha plus beta activity in Table B-3 reflect the efficiency modifications. DTEs total efficiency calculation has also been updated to reflect the weighted surface efficiency correction.

However, ORISE is unable to account for the count rate variations observed during the first site visit; as the same instrumentation and operating parameters were used during the second site visit, and there was no identifiable variation between the DTE and ORISE observed count rates.

The FSS data packages that were reviewed accurately and adequately described the sequence of FSS activities and the radiological conditions at the site. All confirmatory measurement results were below the respective DCGLGA values for the ROCs as specified in the FSSP. Soil, tar, and gravel sample activities were below 10% of the DCGLW values. ORISEs survey data verifies that the radiological conditions of the confirmatory survey units are below the DCGLGA value requirements stated in the licensees Final Status Survey Plan (DTE 2009). Confirmatory survey activities validated the licensees classifications, radiological status and satisfaction of the guidelines.

Enrico Fermi Atomic Power Plant, Unit 1 11 2018-SR-01-1

11.0 REFERENCES

DTE Energy (DTE). Enrico Fermi Atomic Power Plant, Unit 1 License Termination Plan, Revision 2. Newport, MI; March 23, 2009.

DTE Energy. NSEF-10-0027 Fermi 1 Final Status Survey DCGL Selection for Survey Units. Newport, MI; July 29, 2010.

DTE Energy. ESG01_01 All FSS Data. Newport, MI; January 20, 2012.

Oak Ridge Associated Universities (ORAU). Quality Program Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, TN; June 30, 2009.

Oak Ridge Institute for Science and Education (ORISE). Survey Procedures Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, TN; May 1, 2008.

Oak Ridge Institute for Science and Education. Survey Project-Specific Plan for the Decommissioning of the Enrico Fermi Atomic Power Plant, Unit 1. Oak Ridge, TN; May 28, 2010a.

Oak Ridge Institute for Science and Education. Laboratory Procedures Manual for the Independent Environmental Assessment and Verification Program. Oak Ridge, TN; May 28, 2010b.

Oak Ridge Institute for Science and Education. Revised Final Report No. 2: Independent Confirmatory Survey Summary and Results for the Enrico Fermi Atomic Power Plant, Unit 1, Newport, Michigan.Oak Ridge, TN; October 27, 2011.

U.S. Nuclear Regulatory Commission (NRC). Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM), NUREG-1575; Revision 1. Washington, DC; August 2000.

Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 APPENDIX A FIGURES

Enrico Fermi Atomic Power Plant, Unit 1 A-1 2018-SR-01-1 Figure A-1: Location of the Detroit Edison Enrico Fermi Atomic Power Plant, Units 1 and 2

Enrico Fermi Atomic Power Plant, Unit 1 A-2 2018-SR-01-1 Figure A-2: Enrico Fermi Atomic Power Plant, Unit 1 Plot Plan

Enrico Fermi Atomic Power Plant, Unit 1 A-3 2018-SR-01-1 Figure A-3: Turbine Building, Fourth FloorAlpha plus Beta Radiation Floor Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-4 2018-SR-01-1 Figure A-4: Turbine Building, Fifth FloorAlpha plus Beta Radiation Floor Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-5 2018-SR-01-1 Figure A-5: Turbine Building, Sixth FloorAlpha plus Beta Radiation Floor Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-6 2018-SR-01-1 Figure A-6: Steam Generator Building, Upper LevelAlpha plus Beta Radiation Floor Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-7 2018-SR-01-1 Figure A-7: Steam Generator Building, BasementAlpha plus Beta Radiation Floor Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-8 2018-SR-01-1 Figure A-8: Fermi 1External Gamma Radiation Scans of Open Land Areas

Enrico Fermi Atomic Power Plant, Unit 1 A-9 2018-SR-01-1 Figure A-9: Turbine Building, Fifth Floor RoofExterior Gamma Radiation Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-10 2018-SR-01-1 Figure A-10: Turbine Building, Seventh Floor RoofExterior Gamma Radiation Scans

Enrico Fermi Atomic Power Plant, Unit 1 A-11 2018-SR-01-1 Figure A-11: Turbine Building, Fourth FloorAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-12 2018-SR-01-1 Figure A-12: Turbine Building, Fifth FloorAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-13 2018-SR-01-1 Figure A-13: Turbine Building, Sixth FloorAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-14 2018-SR-01-1 Figure A-14: Steam Generator Building, Upper LevelAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-15 2018-SR-01-1 Figure A-15: East Sodium GalleryAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-16 2018-SR-01-1 Figure A-16: Waste Gas BuildingAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-17 2018-SR-01-1 Figure A-17: West Sodium GalleryAlpha plus Beta Direct Measurement Locations

Enrico Fermi Atomic Power Plant, Unit 1 A-18 2018-SR-01-1 Figure A-18: Fermi 1Exterior Soil and Turbine Roof Samples

Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 APPENDIX B TABLES

Enrico Fermi Atomic Power Plant, Unit 1 B-1 2018-SR-01-1 TABLE B-1:

SURFACE ACTIVITY AND SOIL CONCENTRATION DCGLS Radionuclide Building Surfacea (dpm/100cm2)

Soila (pCi/g)

Ag-108m 1.8E+04 7.8 Am-241 5.0E+03 130 C-14 1.0E+07 450 Cm-242 3.1E+05 7,700 Cm-243 7.2E+03 78 Co-60 1.1E+04 5.1 Cs-134 1.7E+04 8.3 Cs-137 3.9E+04 17 Eu-152 2.2E+04 11 Eu-154 2.0E+04 11 Eu-155 3.6E+05 400 Fe-55 4.1E+07 34,000 H-3 2.9E+08 31,000 Na-22 1.3E+04 6.2 Nb-94 1.5E+04 7.9 Ni-59 6.0E+05 11,000 Ni-63 3.6E+07 4,000 Pu-238 5.7E+03 160 Pu-239 5.0E+03 140 Pu-240 5.0E+03 140 Pu241 2.7E+05 5,200 Sb-125 5.9E+04 34 Sr-90 1.4E+05 12 Tc-99 1.4E+07 20 aDCGLW values correspond to an annual dose of 25 mrem.

Enrico Fermi Atomic Power Plant, Unit 1 B-2 2018-SR-01-1 TABLE B-2:

ESG01-01 COMPARATIVE DIRECT MEASUREMENT RESULTS DTE Data ORISE Data DTE:ORISE Ratio Location cpm dpm/100cm2 total (0.10) cpm dpm/100cm2 total (0.21)

ESG01-01-21 174 1,200a 273 1,000 1.2b ESG01-01-22 134 890 304 1,100 0.81 ESG01-01-23 163 1,100 331 1,300 0.85 ESG01-01-24 147 970 334 1,300 0.75 ESG01-01-25 119 790 292 1,100 0.72 ESG01-01-26 141 930 296 1,100 0.85 aSurface activity calculations have been rounded to two significant figures.

bDTE:ORISE ratio was derived from the rounded surface activity values.

Enrico Fermi Atomic Power Plant, Unit 1 B-3 2018-SR-01-1 TABLE B-3:

FERMI 1 RADIONUCLIDE SURFACE ACTIVITY LEVELS Building/Area Measurement ID Surface Alpha plus Beta Gross Activity (dpm/100cm2)

Turbine Building TBNa / 4th Floor TBN01-04-01 Concrete Floor 1,400 TBNa / 4th Floor TBN01-04-02 Concrete Floor 1,200 TBNa / 4th Floor TBN01-04-03 Metal I-beam 790 TBNa / 4th Floor TBN01-04-04 Metal 910 TBNa / 5th Floor TBN01-04-05 Concrete Floor 1,400 TBNa / 5th Floor TBN01-04-06 Concrete Floor 1,500 TBNa / 5th Floor TBN01-04-07 Corrugated Transite 1,400 TBNa / 5th Floor TBN01-04-08 Metal Ledge 1,200 TBNa / 6th Floor TBN01-04-09 Concrete Floor 1,400 TBNa / 6th Floor TBN01-04-10 Concrete Floor 1,300 TBNa / 6th Floor TBN01-04-11 Concrete Floor 1,300 TBNa / 6th Floor TBN01-04-12 Corrugated Transite 1,500 Steam Generator Building SGBa / 1st Floor SGB01-01-01 Cinder Block 1,600 SGBa / 1st Floor SGB01-01-02 Concrete Floor 1,100 SGBa / 1st Floor SGB01-01-03 Concrete Floor 1,200 SGBa / 1st Floor SGB01-01-04 Concrete Floor 1,100 West Sodium Gallery WSGa WSG01-01-01 Concrete Floor 700 WSGa WSG01-01-02 Concrete Wall 600 WSGa WSG01-01-03 Concrete Floor 570 Waste Gas Building WGBb / Valve Room WGB01-01-01 Concrete Wall 1,300 WGBb / Valve Room WGB01-01-02 Concrete Floor 1,300 WGBb / Valve Room WGB01-01-03 Concrete Wall 1,200 WGBb / Basement WGB01-01-04 Concrete Floor 990 WGBb / Basement WGB01-01-05 Concrete Wall 1,000 WGBb / Basement WGB01-01-06 Concrete Wall 1,000 WGBb / Tank Room 2 WGB01-01-07 Concrete Wall 990 WGBb / Tank Room 2 WGB01-01-08 Concrete Floor 1,300 WGBb / Tank Room 2 WGB01-01-09 Concrete Wall 1,300 WGBb / Tank Room 1 WGB01-01-10 Concrete Floor 1,100 WGBb / Tank Room 1 WGB01-01-11 Concrete Wall 1,200

Enrico Fermi Atomic Power Plant, Unit 1 B-4 2018-SR-01-1 TABLE B-3:

FERMI 1 RADIONUCLIDE SURFACE ACTIVITY LEVELS Building/Area Measurement ID Surface Alpha plus Beta Gross Activity (dpm/100cm2)

WGBb / Tank Room 1 WGB01-01-12 Concrete Wall 1,600 East Sodium Gallery ESGc ESG01-01-21 Concrete Floor 1,000 ESGc ESG01-01-22 Concrete Floor 1,100 ESGc ESG01-01-23 Concrete Floor 1,300 ESGc ESG01-01-24 Concrete Floor 1,300 ESGc ESG01-01-25 Concrete Floor 1,100 ESGc ESG01-01-26 Concrete Ceiling 1,100 aDTE FSS documents did not provide sufficient data for ORISE to calculate a total weighted efficiency for the Turbine Building, Steam Generator Building, or West Sodium Gallery.

bThe total weighted efficiency for the Waste Gas building was calculated based on the concentrations DTE provided for cesium-137, cobalt-60 and strontium-90.

cThe total efficiency for the measurements collected in the East Sodium Gallery was based on cobalt-60.

Enrico Fermi Atomic Power Plant, Unit 1 B-5 2018-SR-01-1 TABLE B-4:

FERMI 1 RADIONUCLIDE CONCENTRATIONS OF SELECTED GAMMA EMMITING RADIONUCLIDES IN SOIL AND BUILDING MEDIA (pCi/g)

ORISE Sample IDa Eu-155 Eu-152 Eu-154 Cs-137 Co-60 Am-241 U-235 Th-234 2018M0001 0.05 +/- 0.10b 0.01 +/- 0.12

-0.30 +/- 0.18 1.78 +/- 0.14 0.03 +/- 0.04 0.15 +/- 0.09 0.38 +/- 0.04 2.78 +/- 0.47 2018M0002

-0.02 +/- 0.10

-0.21 +/- 0.13 0.09 +/- 0.17 0.08 +/- 0.04 0.00c +/- 0.04 0.00c +/- 0.06 0.17 +/- 0.04 0.57 +/- 0.39 2018S0001 0.01 +/- 0.04

-0.08 +/- 0.05

-0.02 +/- 0.08 0.11 +/- 0.02 0.02 +/- 0.03

-0.01 +/- 0.04 0.13 +/- 0.01 1.38 +/- 0.21 aSee Figure A-18 bUncertainties represent the 95% confidence interval based on total propagated uncertainties.

cZero values for sample results are due to rounding.

Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 APPENDIX C MAJOR INSTRUMENTATION

Enrico Fermi Atomic Power Plant, Unit 1 C-1 2018-SR-01-1 The display of a specific product is not to be construed as an endorsement of the product or its manufacturer by the author or his employer.

C.1 SCANNING AND MEASUREMENT INSTRUMENT/DETECTOR COMBINATIONS C.1.1 Gamma Ludlum NaI Scintillation Detector Model 44-10, Crystal: 5.1 cm x 5.1 cm (Ludlum Measurements, Inc., Sweetwater, TX) coupled to:

Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, TX) coupled to:

Trimble GeoXH Receiver and Data Logger (Trimble Navigation Limited, Sunnyvale, CA)

C.1.2 Alpha and Alpha Plus Beta Ludlum Gas Proportional Detector Model 43-68, 126cm2 physical area coupled to:

Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, TX)

Ludlum Gas Proportional Detector Model 43-37, 582cm2 physical area coupled to:

Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, TX) coupled to:

Trimble S3 Total Station with TSC2 controller (Trimble Navigation Limited, Sunnyvale, CA)

C.2 LABORATORY ANALYTICAL INSTRUMENTATION High Purity Extended Range Intrinsic Detector CANBERRA/Tennelec Model No: ERVDS30-25195 (Canberra, Meriden, CT)

Used in conjunction with:

Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, TN) and Multichannel Analyzer Canberras Apex Gamma Software Dell Workstation (Canberra, Meriden, CT)

Enrico Fermi Atomic Power Plant, Unit 1 C-2 2018-SR-01-1 LABORATORY ANALYTICAL INSTRUMENTATION (CONTINUED)

High Purity Extended Range Intrinsic Detector Model No. GMX-45200-5 (AMETEK/ORTEC, Oak Ridge, TN) used in conjunction with:

Lead Shield Model SPG-16-K8 (Nuclear Data)

Multichannel Analyzer Canberras Apex Gamma Software Dell Workstation (Canberra, Meriden, CT)

High-Purity Germanium Detector Model GMX-30-P4, 30% Eff.

(AMETEK/ORTEC, Oak Ridge, TN)

Used in conjunction with:

Lead Shield Model G-16 (Gamma Products, Palos Hills, IL) and Multichannel Analyzer Canberras Apex Gamma Software Dell Workstation (Canberra, Meriden, CT)

Enrico Fermi Atomic Power Plant, Unit 1 2018-SR-01-1 APPENDIX D SURVEY AND ANALYTICAL PROCEDURES

Enrico Fermi Atomic Power Plant, Unit 1 D-1 2018-SR-01-1 D.1 PROJECT HEALTH AND SAFETY The proposed survey and sampling procedures were evaluated to ensure that any hazards inherent to the procedures themselves were addressed in current job hazard analyses. Additionally, upon arrival on site, a walk-down of the site was performed to identify hazards present and a pre-job integrated safety management checklist was completed and discussed with field personnel. All survey and laboratory activities were conducted in accordance with ORISE health and safety and radiation protection procedures.

D.2 CALIBRATION AND QUALITY ASSURANCE Calibration of all field and laboratory instrumentation was based on standards/sources, traceable to National Institute of Standards and Technology (NIST).

Analytical and field survey activities were conducted in accordance with procedures from the following documents of the Independent Environmental Assessment and Verification Program:

  • Survey Procedures Manual (ORISE 2008)
  • Laboratory Procedures Manual (ORISE 2010b)
  • Quality Program Manual (ORAU 2009)

The procedures contained in these manuals were developed to meet the requirements of Department of Energy (DOE) Order 414.1C and the U.S. Nuclear Regulatory Commission Quality Assurance Manual for the Office of Nuclear Material Safety and Safeguards and contain measures to assess processes during their performance.

Quality control procedures include:

  • Daily instrument background and check-source measurements to confirm that equipment operation is within acceptable statistical fluctuations.
  • Participation in Mixed Analyte Performance Evaluation Program (MAPEP), NIST Radiochemistry Intercomparison Program (NRIP), and Intercomparison Testing Program (ITP) Laboratory Quality Assurance Programs.

Enrico Fermi Atomic Power Plant, Unit 1 D-2 2018-SR-01-1

  • Training and certification of all individuals performing procedures.
  • Periodic internal and external audits.

D.3 SURVEY PROCEDURES D.3.1 Surface Scans A sodium iodide (NaI) scintillation detector was used to scan for elevated gamma radiation.

Identification of elevated radiation levels was based on increases in the audible signal from the recording and/or indicating instrument. Additionally, the detectors were coupled to global positioning system (GPS) units with data loggers enabling real-time recording in one-or two-second intervals of both geographic position and the gamma count rate. Position and gamma count rate data files were transferred to a computer system, positions differentially corrected, and the results plotted on geo-referenced aerial photographs. Positional accuracy was within 0.5 meters at the 95th percentile.

The scan minimum detectable concentration for the NaI scintillation detectors was approximately 3.4 pCi/g for cobalt-60 and 6.4 pCi/g for cesium-137, as provided in NUREG-1507.

D.3.2 Surface Activity Measurements Measurements of total activity levels were performed using gas proportional detectors with portable ratemeter-scalers. Surface activity measurements were performed on floors, lower walls and at locations of elevated direct radiation.

Count rates (cpm), which were integrated over one minute with the detector held in a static position, were converted to activity levels (dpm/100cm2) by dividing the count rate (in counts per minute) by the physical detector area of 126 cm2, and by the total efficiency (i xs). Individual building material background measurements were not subtracted for the confirmatory surveys performed at the Fermi 1 site in order to match the DTE Final Status Survey procedure. Therefore, confirmatory measurement data represent gross activity levels for the remaining structures and surfaces.

The 2 instrument efficiencies (i) were as follows: 0.38 for the gas proportional detectors calibrated to thorium-230; 0.37 for carbon-14; 0.46 for technetium-99; 0.59 for thalium-204 and 0.56 for strontium-90. The source efficiency factor (s) was 0.25 for alpha measurements. Both 0.25 and 0.50

Enrico Fermi Atomic Power Plant, Unit 1 D-3 2018-SR-01-1 were used for the beta measurements, dependent upon the beta energy level of the contaminant(s) within specific survey units. The total beta efficiency in survey unit ESG01-01 was 0.11 based on the Tc-99 i of 0.46 and s of 0.25 representing the beta energy distribution of Co-60. Survey units TBN01-04, SGB01-01, WSG01-01 and WGB01-01 have a DCGLGA for radionuclides including cesium-137 and cobalt-60.

The total efficiency for direct measurements varied based on the applicable ROCs per survey unit.

Sufficient data were not provided to calculate a total weighted efficiency for the TBN01-04, SGB01-01 and WSG01-01 survey units. The total efficiency for technetium-99 was used to calculate the gross activity in these survey units. The total weighted efficiency for the WGB01-01 survey unit was calculated using the concentrations for the ROCs provided in the DTE survey packages. That efficiency was calculated using the following formula:

()()() + ()()() + ()()() =

(0.46)(0.5)(0.38) + (0.46)(0.25)(0.01) + (0.56)(0.5)(0.6) = 0.26 The total efficiency for technetium-99 was used to calculate the gross activity of cobalt-60 in the ESG01-01 survey unit.

D.3.3 Soil Sampling Approximately 0.5 to 1 kilogram (kg) of soil/tar and gravel was collected at each sample location.

Collected samples were placed in a plastic bag, sealed, and labeled in accordance with ORISE survey procedures.

D.4 RADIOLOGICAL ANALYSIS D.4.1 Gamma Spectroscopy Samples were dried, mixed, crushed, and/or homogenized as necessary, and a portion sealed in a 0.5-liter Marinelli beaker or other appropriate container. The quantity placed in the beaker was chosen to reproduce the calibrated counting geometry. Net material weights were determined and the samples counted using intrinsic germanium detectors coupled to a pulse height analyzer system.

Background and Compton stripping, peak search, peak identification, and concentration calculations were performed using the computer capabilities inherent in the analyzer system. All Total

Enrico Fermi Atomic Power Plant, Unit 1 D-4 2018-SR-01-1 Absorption Peaks (TAP) associated with the ROCs were reviewed for consistency of activity. TAPs used for determining the activities of ROCs and the typical associated Minimum Detection Concentrations (MDC)s for a one-hour count time were:

TABLE D-1: MDC DERIVED FROM TOTAL ABSORPTION PEAK Radionuclide TAP (MeV)

MDC (pCi/g)

Am-241 0.059 MeV 0.11 Co-60 1.173 MeV 0.06 Cs-137 0.662 MeV 0.05 Eu-152 0.344 MeV 0.11 Eu-154 0.723 MeV 0.13 Eu-155 0.105 MeV 0.07 U-235 0.143 MeV (or 0.186 MeV) 0.24 (or 0.05)

U-238 0.063 MeV from Th-234 0.75 Spectra were also reviewed for other identifiable TAPs. The determination of MDCs was derived from the progeny of U-238, Thorium-234 for U-238. Soil concentration calculations were based on the assumption that thorium-234 was in equilibrium with U-238.

D.5 DETECTION LIMITS Detection limits, referred to as minimum detectable concentrations, were based on 95 percent confidence level via NUREG 1507 method; Equation 3-10:

(

1002) =

3 + 4.65 1

1 +

2 2 +

Where:

Cb=

Average background count in time K =

Constant for detection efficiency and probe geometry T =

Paired observations of the sample and blank Because of variations in background levels, measurement efficiencies, and contributions from other radionuclides in samples, the detection limits differ from sample to sample and instrument to instrument.

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