ML16250A433

Forward Final Report on Independent Confirmatory Survey Summary and Results for the Discharge Canal and Annex Building 6 at the Humboldt Bay Power Plant, Eureka, California

ML16250A433
Person / Time
Site:	Humboldt Bay
Issue date:	10/28/2015
From:	Harpenau E M Oak Ridge Associated Universities
To:	John Hickman Division of Decommissioning, Uranium Recovery and Waste Programs
References
Download: ML16250A433 (38)

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OAAU Further Together October 28, 2015 Mr.John Hickman U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards Division of Decommissioning, Uranium Recovery, and Waste Programs Reactor Decommissioning Branch Mail Stop: T8F5 11545 Rockville Pike Rockville, MD 20852

SUBJECT:

FINAL REPORT-INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE DISCHARGE CANAL AND ANNEX BUILDING 6 AT THE HUMBOLDT BAY POWER PLANT, EUREKA, CALIFORNIA (RFTA NO.15-006); DCN 5272-SR-01-0

Dear Mr. Hickman:

ORAU is pleased to provide the enclosed final report detailing the independent confirmatory survey activities of the Discharge Canal and Annex Building 6 at the Humboldt Bay Power Plant in Eureka, California. This report provides the summary and results of activities performed by ORAU, under the Oak Ridge Institute for Science and Education (ORISE) contract, during the period of July 20-23, 2015. Comments for additional clarification on the September 2015 draft version of this report have been incorporated. You may contact me at 865.241.8793 or Erika Bailey at 865. 576.6659 if you have any questions. Sincerely, Evan M. Harpenau Health Physicist ORAU EMH:fs electronic distribution: G. Schlapper, NRC S. Roberts, ORAU E. Bailey, ORAU D. Stearns, NRC T. Vitkus, ORAU File/5272 P.O. Box 117 Oak Ridge, TN 37831

• www.orau.org INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE DISCHARGE CANAL AND ANNEX BUILDING 6 AT THE HUMBOLDT BAY POWER PLANT, EUREKA, CALIFORNIA FINAL REPORT ORi\U Further. Together. Prepared by Evan M. Harpenau OCTOBER 2015 Prepared for the U.S. Nuclear Regulatory Commission Prepared by ORAU under the Oak Ridge Institute for Science and Education contract, nwnber DE-AC05-060R23100, with the U.S. Department of Energy under interagency agreement (NRC FIN No. F-1244) between the U.S. uclear Regulatory Commission and the U.S. Department of Energy. Humboldt Bay Confirmatory Survey Report 5272-SR-01-0 ORAU INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE DISCHARGE CANAL AND ANNEX BUILDING 6 AT THE HUMBOLDT BAY POWER PLANT, EUREKA, CALIFORNIA EXECUTIVE SUMMARY The U.S. uclear Regulatory Commission (NRC) requested that ORAU, working under the Oak Ridge Institute for Science and Education (ORISE) contract, perform an independent confirmatory survey at the Humboldt Bay Power Plant (HBPP) in Eureka, California. Pacific Gas and Electric Company (PG&E), who owns and operates the site, is currently engaged in the decontamination and decommissioning of the Unit 3 boiling water nuclear reactor, along with the impacted areas associated with its operation. This report focuses on confirmatory survey activities performed in support of decommissioning the Discharge Canal and Annex Building 6. ORAU performed independent assessment activities including gamma, beta, and alpha radiation surveys and soil sampling during the period of July 20-23, 2015. Confirmatory survey activities included surveys of two structural survey units with 29 side-by-side direct measurements; 20 independent direct measurements and smears; and one land area unit with two split and six random soil samples. The results of ORAU gamma, beta and alpha, radiation surveys, combined with laboratory analytical results from soil samples, support the conclusion that survey unit OOL 01-02 of the Discharge Canal and Annex Building 6 satisfies the NRC-approved soil and surface activity derived concentration guideline levels (DCGLs) described in PG&E's final status survey planning documents. Humboldt Bay Confirmatory Survey Report 5272-SR-01-0 OIV\.U INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE DISCHARGE CANAL AND ANNEX BUILDING 6 AT THE HUMBOLDT BAY POWER PLANT, EUREKA, CALIFORNIA 1. INTRODUCTION The Pacific Gas & Electric Company (PG&E) operated the Humboldt Bay Power Plant (HBPP) Unit 3 nuclear reactor near Eureka, California under Atomic Energy Commission (AEC) provisional license number DPR-7. HBPP Unit 3 achieved initial criticality in February 1963 and begun commercial operations in August 1963. Unit 3 was a natural circulation boiling water reactor with a direct-cycle design. Stainless steel fuel claddings were used from startup until cladding failures resulted in plant system contamination. A number of spills and gaseous releases were reported during operations, resulting in a range of mitigation activities (ESI 2008). In July 1973, Unit 3 was shut down for annual refueling and seismic modifications. However, by December 1980 it was concluded that completing the required upgrades and restarting Unit 3 would be cost prohibitive. PG&E decided in June 1983 to decommission Unit 3, received a possession-only license amendment, and placed the unit into cold shutdown and safety storage (SAFSTOR). The impacted areas associated with nit 3 are currently undergoing decommissioning. As part of the Humboldt Bay Repowering Project (HBRP), PG&E has built ten new fossil fuel units (16.3 MWe [megawatt electric] each) on the site in the vicinity of Unit 3. Decommissioning activities have also been completed on the adjacent fossil fuel Units 1 and 2, with all materials being removed to ground level (ESI 2008). The U.S. Nuclear Regulatory Commission (NRC) is responsible for oversight of permitted license activities that are currently being conducted at Unit 3 of the HBPP. The NRC requested that ORAU, under the Oak Ridge Institute for Science and Education (ORISE) contract, perform confirmatory surveys of the Discharge Canal and Annex Building 6. Hereafter, Annex Building 6 will be referred to as the Annex. Humboldt Bay Confirmatory Survey Report 5272-SR-01-0 L OAAU 2. SITE DESCRIPTION The HBPP site, owned by PG&E, consists of 143 acres on the southern edge of Humboldt Bay four miles southwest of the town of Eureka, in Humboldt County, California (Figure A-1). PG&E maintains ten new operating electric generating units at the HBPP site (in the New Generation Footprint Area) that run on fossil fuels. The new fossil fuel electric-generating units have replaced the former Fossil Units 1 and 2. The remaining property includes mostly open areas and protected wetlands. This report focuses on the Discharge Canal and the interior and exterior surfaces of the Annex, pictured in Figure 2.1 courtesy of Google Earth 2015. The Discharge Canal is located in the northern section of the HBPP site. The middle portion of the Discharge Canal, survey unit (SU) OOL 01-02, contains approximately 1,018 square meters of surface area, primarily comprised of silt and soil (PGE 2015a and 2015b). Following remediation, groundwater seepage was regularly pumped from the SU to maintain suitable conditions for performing surveys. The Annex, SUs OFA 01-01 and OFA 01-02, is a concrete block structure with a footprint of approximately 272 m2 (total area of 745 m2 including exterior walls and roof) located across from the Main Office Building and is bounded by SU OOL10 on the north, west, and south sides and S OOL08 on the east. It was constructed in the 1980s and primarily used for administrative office space (PGE 2015c). Figure 2.1. Discharge Canal and Office Annex Building Location Humboldt Bay Confirmatory Survey Report 2 5272-SR-01-0 ORAU 3. OBJECTIVES The objectives of the confirmatory survey activities were to provide independent contractor field data reviews and to generate independent radiological data for use by the NRC in evaluating the accuracy and adequacy of the licensee's procedures and results. 4. APPLICABLE SITE GUIDELINES The primary radionuclides of concern (ROCs) identified for the Discharge Canal and Annex are beta-gamma emitters-fission and activation products-resulting from reactor operation. Licensee documentation states that two specific ROCs, cobalt-60 and cesium-137, account for over 95% of the total activity observed in the canal and Class 3 SUs. Though all site-related ROCs are not listed for the canal soils in Table 4.1, the dose contributions from radionuclides determined to be insignificant have been subtracted from the overall 25 mrem/yr release criteria. NUREG-1757 guidance describes radionuclides and exposure pathways that contribute no greater than 10% of the dose criteria to be insignificant contributors. It also details that dose contributions from all radionuclides and pathways must be accounted for in demonstrating compliance with the release criteria (NRC 2006). PG&E determined the insignificant radionuclide dose contribution to be 1.1 millirem per year (mrem/yr). The values presented in Table 4.1 are the derived concentration guideline levels that have been adjusted down accordingly to account for insignificant radionuclide 1.1 mrem/y dose and therefore correspond with a total dose of 23.9 mrem/yr (PGE 2015b). Table 4.1. Discharge Canal Soil DCGL"s Scaled to 23.9 mrem/yr ROC Inventory Limit (pCi/g) Co-60 3.6 Nb-94 6.8 Am-241 23.9 Cs-137 7.6 Eu-152 9.6 Eu-154 9.0 Np-237 1.1 Humboldt Bay Confirmatory Survey Report 3 5272-SR-01-0 ORAu Each scaled radionuclide-specific represents the concentration above background of a residual radionuclide that would result in a radiological dose of 23.9 millirem per year (mrem/yr) to the average member of the critical group. For consistency with the licensee's application of DCGLs to gross soil and surface activity concentrations such that data were not corrected for background contributions, ORAU also reported data results without background corrections. Because each of the individual represents 23.9 mrem/yr, the sum-of-fractions (SOF) approach was used to demonstrate compliance with the dose limit. SOF calculations were performed as follows: n SOFTOTAL = i SOFi = . *-o L w.1 J-j=O Where Ci is the concentration of ROC "j," and is the for ROC "j." Note that gross concentrations were considered here for conservatism. PG&E's characterization data indicated that surface activity levels were near background for the Annex. As such, final status survey (FSS) and confirmatory results were expected to represent a small fraction of the site's overall surface activity DCGLs, listed in Table 4.2. Table 4.2. Surface Activity DCGLs ROC" DCGL ROC DCGL ROC (dpm/100cm2)b (dpm/100cm2) Am-241 3.00E+03 Eu-152 2.70E+04 Pu-238 C-14 7.00E+06 Eu-154 2.50E+04 Pu-239 Cm-243 4.30E+03 H-3 1.80E+08 Pu-240 Cm-244 5.50E+03 I-129, 4.90E+04 Pu-241 Cm-245 2.20E+03 b-94 1.90E+04 Sr-90 Cm-245 2.70E+03 Ni-59 6.30E+07 Tc-99 Co-60 1.30E+04 Ni-63 2.40E+07 Cs-137 4.60E+04 Np-237 2.40E+03 *From the Office Annex Final Status Survey Planning Worksheet (PGE 201Sc) hdpm/100cm2 = disintegrations per minute per 100 square centimeters Humboldt Bay Confirmatory Survey Report 4 DCGL (dpm/100cm2) 3.40E+03 3.10E+03 3.10E+03 1.40E+05 9.70E+04 9.60E+06 5272-SR-01-0 ORi\U The surface activity measurements that were above instrument minimum detection capabilities were primarily attributed to Cs-137 and Co-60, with 94% of the activity coming from Cs-137 and 6% from Co-60 (PGE 2015c). The fractional distribution information was used to calculate a gross area DCGL (DCGLGJ for both beta/gamma and alpha surface activities (PGE 2015c). The DCGLGAs are presented after Table 4.2.

• DCGLGA beta/ gamma

• DCGLGA alpha 4.06E+04 dpm/100cm2 3.0E+03 dpm/100cm2 5. PROCEDURES The confirmatory survey activities were conducted during the period of July 20-23, 2015, in accordance with the project-specific confirmatory survey plan, the ORAU Radiological and Environmental Survry Procedure Manual, and the ORAU Environmental Services and Radiation Training Quality Program Manual (ORAU 2015a, 2015b, and 2015c). 5.1 SURFACE SCANS ORAU performed high-density gamma radiation scans of the accessible soil surfaces in the Discharge Canal. Gamma scans were performed using a Ludlum Model 44-10 sodium iodide (Nal) detector coupled to Ludlum Model 2221 ratemeter-scaler \vith audible indicator. Additionally, the gamma detector/ratemeter pair was coupled to a global positioning system (GPS) that enabled real-time gamma count rate and spatial data capture (Figure A-2). Although the area was pumped overnight, groundwater seepage in the bottom of the Discharge Canal prevented scan coverage in portions of that area. Low-to medium-density beta scans were performed on the interior and exterior of the Annex that included the floor, walls, and roof. Beta scans were performed using Ludlum Model 44-142 plastic scintillation detectors coupled to Ludlum Model 2221 ratemeter-scalers with audible indicators. Additionally, data loggers were coupled to the detector/ ratemeter pair to allow for electronic data capture for dataset evaluation and presentation (Figures A-3 and A-4). Beta radiation surface scans concentrated on areas with the highest likelihood of contamination potential (i.e., high-traffic pathways, accumulation points, and drainage paths). Humboldt Bay Confirmatory Survey Report 5 5272-SR-01-0 OAAU 5.2 SURFACE ACTIVITY MEASUREMENTS Independent direct surface activity measurements were collected on the Annex's interior and exterior surfaces to assess total residual alpha and beta activity levels. ORAU collected surface measurements from randomly-generated locations using a Ludlum Model 43-92 and Model 44-142 plastic scintillation detectors. Visual Sample Plan (VSP) software, Version 7.4 was used to generate random measurement locations. There were no judgmental measurement locations judgmentally as no elevated direct radiation, with respect to the alpha and beta DCGLGAs, was observed during scan surveys (Figures A-5 and A-6). Additionally, as PG&E elected to report PSS surface activity results based on gross rather than net measurement data, ORAU did not subtract material-specific backgrounds from measurement data, such that the results would be directly comparable with the licensee's. Smear samples to determine removable gross alpha and gross beta activity levels were also collected at each random measurement location. In addition, ORAU collected side-by-side direct measurements at PG&E's PSS locations in the two SUs associated with the Annex to determine if the PG&E and ORAU instrumentation exhibited good correlation as well as review the results for any systematic bias. 5.3 SOIL SAMPLING A ranked set sampling (RSS) design was used to estimate the mean radionuclide concentration in the Discharge Canal. The number of locations to evaluate and sample within each SU were calculated by using the contractor's PSS planning data and VSP (PGE 2015b). As a result of the sample planning inputs, 18 ranking locations were evaluated in SU OOL 01-02 of the canal. Following completion of walkover surveys, the RSS locations were laid out as illustrated in Figure A-7. A one-minute static gamma measurement was made with the Nal detector at each ranking location. The surface measurements were then ranked, which resulted in the selection of six locations for sampling. The six sample locations are presented in Figure A-8. At the RC's request, ORAU collected two split samples from locations that PG&E had selected judgmentally from the water-saturated portion of the canal. Due to standing water in the canal and abundant water content in the samples themselves, ORAU was not able to collect direct Humboldt Bay Confirmatory Survey Report 6 5272-SR-01-0 ORi\U measurement data. The PG&E sample IDs corresponding with the ORAU split samples are listed in Table 5.1 below. Table 5.1. Corresponding Split Sample IDs for the Discharge Canal PG&E ORAU OOL 01-02-023-F-B 5272S0007 OOL 01-02-025-F-B 5272S0008 6. SAMPLE ANALYSIS AND DATA INTERPRETATION Samples and data collected on site were delivered to the Radiological and Environmental Analytical Laboratory (REAL) for analysis and interpretation. Sample custody was transferred to the REAL in Oak Ridge, Tennessee. Sample analyses were performed iri accordance with the ORAU Radiological and EnvironmentalAna!Jtical Laboratory Procedures Manual (ORAU 2015d). Soil samples were analyzed by gamma spectroscopy for gamma-emitting ROCs and results were reported in units of picocuries per gram (pCi/ g). Smear samples were analyzed for gross alpha/beta activity using a low-background proportional counter. Smear sample and direct measurement results are reported in units of disintegrations per minute per one hundred square centimeters (dpm/100 cm2). 7. FINDINGS AND RESULTS The results of the confirmatory survey are discussed in the subsections below. 7 .1 DOCUMENT REVIEW The FSSP worksheet for OOL 01-02 uses the terms "hard-to-detect (HTD) nuclides" and "deselected nuclides" when discussing fractional dose contributions to the overall release criteria (PGE 2015b). The discussion aligns with the term "insignificant radionuclides" used in NUREG-1757 which describes radionuclides and exposure pathways that contribute no greater than 10% of the dose criteria to be insignificant contributors, and states that dose contributions from all radionuclides and pathways must be accounted for to demonstrate compliance with the release criteria (NRC 2006). \V'hile both terms, HTD and insignificant radionuclides, could be considered synonymous when discussing the ROCs in the soils of the Discharge Canal, the continued use of Humboldt Bay Confirmatory Survey Report 7 5272-SR-01-0 HTDs could result in improper radionuclide associations in future documents. ORA is of the opinion that the licensee should make the distinction between radionuclides that are in fact hard to detect and those considered to be insignificant contributors to dose. The distinction should then be clearly communicated in future documents to mitigate potential confusion. 7.2 OBSERVATIONS During survey activities of the Annex, SU OFA 01-01, ORAU observed the PG&E technicians collecting removable activity smears after collecting the beta measurement but prior to the alpha direct measurements. Had removable activity been present, this sequence could have led to biased low total alpha surface activity results. The smear sample should be collected after both the beta and alpha direct measurements are completed. In addition, ORA noted that FSS measurement locations placed on the exterior walls of the Annex, S OFA 01-02, had been inverted when compared to the survey map. Each concern was raised with the NRC and the contractor committed to correcting the survey sequence for collecting smears, and to maintaining consistency when laying out wall and ceiling locations for future FSS activities. 7.3 SURFACE SCANS During survey activities in the Discharge Canal (SU OOL 01-02), the upper slopes of the walls proved unsafe to walk on, especially along the northwest side of the SU. As a result, ORAU was not able to survey the northwestern-most portion of the SU. Additionally, continuous inflow of ground water into the bottom of the canal prevented access to approximately one-sixth of the overall SU. The confirmatory gamma scan results of SU OOL 01-02 exhibited radiation levels within the detector background range of 4,200-8,000 gross counts per minute (cpm) (Figure A-2). Scans did not identify any areas for further investigation. Scan results for the interior and exterior surfaces of SUs OFA 01-01 and OFA 01-02, respectively, were also indicative of background radiation levels. Though the interior scan ranged from 120 to 730 cpm, there is no identifiable step-up of the data when displayed in a Q-plot which would typically be indicative of residual contamination (Figure A-3). Additionally, the data show a normal distribution with all data points within three standard deviations of the mean. Much like the interior Humboldt Bay Confirmatory Survey Report 8 5272-SR-01-0 OAAU survey, the scan range for the roof, SU OFA 01-02, was 130 to 960 cpm and showed a normal distribution about the mean without the presence of any steps in the data (Figure A-4). 7.4 SURFACE ACTIVITY MEASUREMENTS Direct alpha and beta radiation activity results during the collection of the random confirmatory measurements were consistent with typical background levels. Total gross surface activity for the confirmatory measurement locations of the Annex interior ranged from 0 to 35 alpha dpm/100 cm2 and 980 to 1,600 beta dpm/100 cm2* The total surface activities observed on the building's exterior ranged from 17 to 300 alpha dpm/100 cm2 and 1,600 to 2,100 beta dpm/100 cm2* Removable activity results for interior and exterior surfaces exhibited a maximum of 1 dpm/100 cm2 alpha and 5 dpm/100 cm2 beta. Tables B-1 and B-2 provide a detailed summary of the independent confirmatory measurement data. The side-by-side measurement data show a general agreement between observed alpha surface activities. However, PG&E's beta results using Ludlum Model 43-68 gas-proportional detectors are consistently lower than ORAU's corresponding data for all but three of the exterior measurement locations on the Annex, and the relative percent difference is greater than 25% for 17 of the 30 measurement results. Though the percent difference could lead to potential issues should surface activities approach the DCGLGAs, the surface activities calculated for the Annex are less than 10% of the release criteria. ORAU will continue to monitor comparative measurement results between instrumentation when additional data are collected and provide notification to the NRC should there be a c;oncern about whether a SU meets or exceeds the release criteria. The side-by-side measurement data are summarized in Tables B-3 and B-4. 7 .5 RADIONUCLIDE CONCENTRATIONS IN SOIL Analytical results for the independent confirmatory and splits samples collected from the Discharge Canal are provided in Table B-5. All six RSS samples exhibited ROC concentrations below the respective analytical minimum detectable concentrations (MDCs) for the ROCs listed in Table 4.2. However, the split samples 5272S0007 and 5272S0008 exhibited ROC concentrations above the respective analytical MDCs for Co-60 and Cs-137, respectively (Table B-5). Even though Co-60 and Cs-137 were identified in the split samples, the concentrations represent a small fraction of the Humboldt Bay Confirmatory Survey Report 9 5272-SR-01-0 ORAu respective Due to the extremely low radionuclide concentrations in the samples and only a couple values being above the analytical MDCs, ORAU did not perform SOF calculations. ORAU has not received PG&E's corresponding data for the split samples, and thus, was unable to perform an inter-laboratory comparison of the results. 8.SUMMARY At the NRC's request, ORAU conducted confirmatory survey activities of SU OOL 01-02 in the Discharge Canal and the interior and exterior surfaces of Annex Building 6, SUs OFA 01-01 and OFA 01-02, at the HBPP during the period of July 20-23, 2015. The survey activities included visual inspections, gamma and beta radiation surface scans, gamma, beta and alpha radiation measurements, and soil and smear sampling. The gamma walkover surface scans and total surface activity measurements were not distinguishable from background. The two split samples collected from PG&E judgmental samples within the Discharge Canal contained radionuclide concentrations above analytical MDCs for Co-60 and Cs-137, but all sample concentrations were well below the respective The minor issue regarding the sequence of performing direct surface activity measurements followed by smears for removable contamination was corrected during onsite confirmatory surveys. For the second issue of measurement locations on exterior walls being inverted for measurement collection, PG&E stated that the same map orientation implemented for splayed walls during the Annex survey would be maintained for future FSS surveys. Another potential issue identified is the systematic bias between PG&E and ORAU beta detector responses. As discussed in Section 7.2, ORAU will continue to evaluate the detector results during upcoming confirmatory surveys. However, based on the results of the confirmatory survey activities, ORAU is of the opinion that Annex Building 6 and SU OOL 01-02 of the Discharge Canal satisfies the RC-approved soil and surface activity DCGLs described in PG&E's final status survey planning documents. Humboldt Bay Confirmatory Survey Report 10 5272-SR-01-0 ORA.u 9. REFERENCES ESI 2008. Historical Site Assessment. Draft. Prepared for the Humboldt Bay Power Plant Pacific Gas & Electric Company. Eureka, California. September. NRC 2006. Consolidated Decommissioning G11ida11ce -Characterization, Sun1ey, and Determination of Radiological Criteria. REG 1757, Vol. 2 Rev, 1. U.S. Nuclear Regulatory Commission. Washington, DC. September. ORAU 2014. ORAU Radiation Protection Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. October. ORA U 201 Sa. Project-specific Plan for the Confirmatory Survey Activities at the Humboldt Bery Power Plant, Discharge Canal and Office Annex Building, Eureka, California. Oak Ridge Associated Universities. Oak Ridge, Tennessee. July 13. ORAU 2015b. ORAU Radiological and Environmental Survey Procedures Man11al Oak Ridge Associated Universities. Oak Ridge, Tennessee. August 6. ORAU 2015c. ORAU Environmental Services and Radiation TrainingQualiry Program Manual Oak Ridge Associated Universities. Oak Ridge, Tennessee. August 7. ORA 2015d. ORAU Radiological and Enviro11me11talA11a!Jtical Laboratory Procedures Manual Oak Ridge Associated Universities. Oak Ridge, Tennessee. May 7. ORAU 2015e. ORAU Health and Scifery Manual Oak Ridge Associated Universities. Oak Ridge, Tennessee. June. PGE 2015a. Email correspondence between D. Randall (PG&E) to E. Harpenau (ORAU) titled, "Draft Survey Plans for the upcoming inspection/ visit at Humboldt Bery Po1ver Plant. "Pacific Gas & Electric Company. San Francisco, California. July 8. PGE 201 Sb. Final Status Survey Planning (FSSP) Worksheet-Discharge Canal (PGE Middle Unit): OOLO 1-02, Rev. OD. RCP FSS-2, Att. 9 .1. Pacific Gas & Electric Company. San Francisco, California. July 7. PGE 201 Sc. Final S talus Survey Planning (FSSP) Worksheet-Office Annex: OF AO 1-01 and OF AO 1-02, Rev. OD. Pacific Gas & Electric Company. San Francisco, California. July 7. Humboldt Bay Confirmatory Survey Report 11 5272-SR-01-0 Humboldt Bay Confirmatory Survey Report APPENDIX A FIGURES 5272-SR-01-0 c:J Discharge Canal Boundary c:J Annex Building 0 35,()(Jll),000 -=:::::i Meters ORAU Humboldt Bay Power Plant Eureka, California Ctta1cd by: A. Kinhlink Date: Scp1cmbcr 22. 201.5 \':\IEA\T GIS il'l Humbokll BaJ Figure A-1. Location of the Humboldt Bay Power Plant, Eureka, California Humboldt Bay Confirmatory Survey Report A-1 5272-SR-01-0

-5451 -6100 --Canal Boundary 7401 -7957 -4801 -5450 6751 -7400 -4151 -4800 -6101-6750 -<4150 0 1.5 5272 Humboldt Bay Canal02 Gamma Walkover 3 ORAU Coated by: th.lid£ Diue; Auci;nt 6, lO'lS Figure A-2. Discharge Canal SU OOL 01-02-Gamma Walkover Scan Humboldt Bay Confirmatory Survey Report A-2 5272-SR-01-0 Annex Building Interior -.. --* ... / 11111.GD 118.0D -_ 110.00 j-oa : 450.00 I GOOD 390.00 1 *.oa 33000 i JClOOO 270.00 240.00 210.00 180.00 15000 120.00 ... 9000 ,. *' Theoretlclll Quantiles (Standard Normal) *Interior Figure A-3. Q-Plot for Interior Scan Survey of the Annex Building 6 I lumboldt Bay onfirmatory Sun-cy Report r\-3 5272-SR-01-0

--IOO.m --100.00 300.00 200.00 100.00 .. .. .. Annex Building Roof .... ... ,..---------*' "' Theoretical Quantiles (Standard Normal) Figure A-4. Q-Plot for Roof Scan Survey of the Annex Building 6 Humboldt Bay Confirmatory Sun-cy Report A-4 5272-SR-01-0 Figure A-5. Random Measurement Locations for Interior of Annex Building 6 Humboldt Bay Confirmatory Survey Report A-5 5272-SR-01-0 5272R0014 Figure A-6. Random Measurement Locations for Exterior of Annex Building 6 Humboldt Bay Confirmatory Survey Report A-6 5272-SR-01-0

• RSS Locations --Canal Boundary 5272 Humboldt Bay Canal02 RSS Locations ORAU Figure A-7. Ranked Set Sample Locations for the Discharge Canal, SUOOL 01-02 Humboldt Bay Confirmatory Survey Report A-7 5272-SR-01-0

• Random Samples --Canal Boundary 5272HumholdtBay Cana102 Sample Locations ORAU Figure A-8. Sample Locations for the Discharge Canal, SUOOL 01-02 Humboldt Bay Confirmatory Survey Report -8 5272-SR-01-0

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Humboldt Bay Confirmatory Survey Report APPENDIXB DATA TABLES 5272-SR-01-0 Table B-1. Surface Activity Levels for Confirmatory Measurements in Interior of Annex Building 6 Count Rate (cpm) Total Surface Activity Removable Activity Location ID Surface (dpm/100 cm2) (dpm/100 cm2) Alpha Beta Alpha Beta* Alpha Beta 5272R0001 Wall 2 339 17 1,400 1 5272R0002 Wall 3 246 26 980 -1 2 5272R0003 Wall 1 335 9 1,300 2 5272R0004 Ceiling 1 368 9 1,500 cl -1 5272R0005 Wall 0 314 0 1,300 -1 0 5272R0006 Ceiling 2 305 17 1,200 -1 2 5272R0007 Floor 1 311 9 1,200 -1 0 5272R0008 Ceiling 3 333 26 1,300 -1 2 5272R0009 Wall 4 277 35 1,100 -1 2 5272R0010 Wall 2 390 17 1,600 -1 0 *Detector calibrated to mula-source beta energies for Co-60 and Cs-13 7 per fracaonaaon prondcd m PG E 201 Sc. Hwnboldt Bay Confirmatory Surycy Report B-1 5272-SR-01-0 Table B-2. Surface Activity Levels for Confirmatory Measurements in Exterior of Annex Building 6 Count Rate (cpm) Total Surface Activity Removable Activity Location ID Surface (dpm/100 cm2) (dpm/100 cm2) Alpha Beta Alpha Beta* Alpha Beta 5272R0011 Wall 30 405 260 1,600 1 4 5272R0012 Roof 6 456 52 1,800 -1 1 5272R0013 Roof 11 473 96 1,900 -1 0 5272R0014 Wall 4 395 35 1,600 -1 0 5272R0015 Wall 2 423 17 1,700 2 5272R0016 Roof 7 520 61 2,100 4 5272R0017 Roof 10 464 87 1,900 2 5272R0018 Roof 9 509 78 2,000 -1 4 5272R0019 Roof 8 466 70 1,900 -1 5 5272R0020 Roof 10 486 87 1,900 1 1 *Detector calibrated to muln-source beta coerg>cs for Co-60 and Cs-137 per fracoonaoon prm,dcd 111 PGE 2015c Humboldt Bay Confirmatory Sun-cy Report B-2 5272-SR-01-0 Table B-3. Surface Activity Levels for Side-By-Side Measurements in Interior of Annex Building 6 PG&E Gross Alpha Count Gross Beta Count Rate Gross Alpha Activity Gross Beta Activity Location ID Surface Rate (cpm) (cpm) (dpm/100 cm') PG&E ORAU PG&E ORAU PG&E OFAOl-01-001 Wall 1.5 1 179 330 23 OFAOl-01-002 Floor 0.5 0 270 357 8 OFA01-01-003b Wall -----OFAOl-01-004 Ceiling 2 1 267 329 31 OFAOl-01-005 Floor 2 6 486 614 31 OFAOl-01-006 Wall 2 4 197 311 31 OFAOl-01-007 Door 0 2 244 346 0 OFAOl-01-008 Wall 0.5 0 185 287 8 OFAOl-01-009 Wall 0.5 2 181 246 8 OFAOl-01-010 Wall 1 2 212 257 15 OFAOl-01-011 Ceiling 0 2 378 415 0 OFAOl-01-012 Floor 1 0 277 346 15 OFAOl-01-013 Floor 0.5 1 272 357 8 OFAOl-01-014 Floor 0.5 2 285 367 8 OFAOl-01-015 Ceiling 0.5 1 240 332 8 , *Detector caLibrated to muln-source beta energies for Co-60 and Cs-137 per fracnonanon provided m PGE 2015c bLocation was inacceRsible, therefore not surveyed. Humboldt Bay Confirmatory Sun-ey Report B-3 ORAU 9 0 -9 52 35 17 0 17 17 17 0 9 17 9 (dpm/100 cm') PG&E ORAU" 669 1,300 1,009 1,400 --997 1,300 1,815 2,500 736 1,200 911 1,400 691 1,100 676 980 792 1,000 1,412 1,700 1,035 1,400 1,016 1,400 1,065 1,500 896 1,300 5272-SR-01-0 PG&E Gross Alpha Count Gross Beta Count Rate Surface Rate cm cm Location ID PG&E ORAU PG&E ORAU OFAOl-02-001 Wall 2 1 337 404 31 9 1,259 1,600 OFAOl-02-002 Wall 6.5 3 355 234 100 26 1,326 940 OFAOl-02-003 Roof 4 5 502 457 62 43 1,875 1,800 OFAOl-02-004 Roof 8.5 6 455 487 131 52 1,700 1,900 OFAOl-02-005 Wall 0.5 3 214 262 8 26 799 1,000 OFAOl-02-006 Roof 5 12 441 494 77 100 1,647 2,000 OFAOl-02-007 Roof 6.5 14 461 441 100 120 1,722 1,800 OFAOl-02-008 Wall 2.5 0 313 397 39 0 1,169 1,600 OFAOl-02-009 Wall 3 4 313 461 46 35 1,169 1,800 OFAOl-02-010 Roof 19.5 34 423 440 301 300 1,580 1,800 OFAOl-02-011 Wall 4 7 380 417 62 61 1,419 1,700 OFAOl-02-012 Wall 2.5 1 304 344 39 9 1,136 1,400 OFAOl-02-013 Roof 9.5 5 476 523 147 43 1,778 2,100 OFAOl-02-014 Roof 5.5 10 502 511 85 87 1,875 2,000 OFAOl-02-015 Roof 5.5 7 417 471 85 61 1,558 1,900 *Detector calibrated to multi-source beta energies for Co-60 and Cs-137 per fractionation pro,-ided in PGE 2015c Humboldt Bay Confirmatory SurYcy Report B-4 5272-SR-01-0 Table B-5. Radionuclide Concentrations in the Discharge Canal (SU OOL 01-02) Sample Sample ID' Am-241 Co-60 Cs-137 Data or Location ID Type or Statistic (pCi/g) (pCi/g) (pCi/g) Random 5272S0001 RSS-1-1-2 -0.07 +/- 0.04' 0.01 +/- 0.03 0.44 +/- 0.05 527250002 RSS-1-2-2 -0.02 +/- 0.08 0.02 +/- 0.02 0.06 +/- 0.02 527250003 RSS-1-3-2 -0.04 +/- 0.04 0.02 +/- 0.04 0.56 +/- 0.06 527250004 RSS-2-1-1 -0.04 +/- 0.06 -0.01+/-0.02 0.02 +/- 0.01 527250005 RSS-2-2-1 0.00 +/- 0.05 0.03 +/- 0.03 0.03 +/- 0.02 527250006 RSS-2-3-1 0.09 +/- 0.11 O.D2 +/- 0.03 0.76 +/- 0.07 Split 527250007 0.02 +/- 0.03 0.01 +/- 0.03 0.38 +/- 0.04 Samples 527250008 O.Ql +/- 0.08 0.00 +/- 0.02 0.08 +/- 0.02 *Uncertamacs represent the 95°10 confidence lcYel, based on total propagated uncertrunacs. hzcro due to rounding Humboldt Bay Confirmatory Sun-ey Report B-5 Eu-152 Eu-154 Nb-94 (pCi/g) (pCi/g) (pCi/g) -0.07 +/- 0.06 -0.12 +/- 0.10 0.02 +/- O.D2 -0.01+/-0.04 -0.09 +/- 0.08 O.OOb +/- 0.01 0.01+/-0.06 -0.07 +/- 0.10 0.01+/-0.02 0.03 +/- 0.03 -0.13 +/- 0.08 0.00 +/- 0.01 0.01+/-0.06 -0.18 +/- 0.12 0.00 +/- 0.02 -0.01+/-0.04 -0.21 +/- 0.11 0.00 +/- 0.02 -0.02 +/- 0.05 -0.23 +/- 0.11 0.02 +/- 0.02 -0.02 +/- 0.04 -0.11 +/- 0.08 0.00 +/- 0.02 5272-SR-01-0 Np-237 (pCi/g) 0.02 +/- 0.04 -0.01+/-0.03 -0.02 +/- 0.04 0.00 +/- 0.02 -0.01 +/- 0.04 0.00 +/- 0.04 0.02 +/- 0.02 -0.01+/-0.03 APPENDIXC SURVEY AND ANALYTICAL PROCEDURES Humboldt Bay Confirmatory Survey Report 5272-SR-01-0 C.1 PROJECT HEALTH AND SAFETY ORAU performed all survey activities in accordance with the ORAU Radiation Protection Manual, the ORAU Health and Sefery Manual, and the ORAU Radiological and Environmental Survey Procedures Manual (ORAU 2014, ORAU 2015e, and ORAU 2015b). Prior to on-site activities, a work-specific hazard checklist was completed for the project and discussed with field personnel. The planned activities were thoroughly discussed with site personnel prior to implementation to identify hazards present. Additionally, prior to performing work, a pre-job briefing and walkdown of the survey areas were completed with field personnel to identify hazards present and discuss safety concerns. Should ORAU have identified a hazard not covered in the ORAU Radiological and Environmental S11rvry Procedures Manual or the project's work-specific hazard checklist for the planned survey and sampling procedures, work would not have been initiated or continued until it was addressed by an appropriate job hazard analysis and hazard controls. C.2 CALIBRATION AND QUALITY ASSURANCE Calibration of all field instrumentation was based on standards/ sources, traceable to ational Institute of Standards and Technology (NIST). Field survey activities were conducted in accordance with procedures from the following ORAU documents:

• ORAU Radiological and Environmental Survey Procedures Manual (ORAU 2015b)

• 0 RAU Radiological and Environmental .AJJa/ytical Laboratory Procedttres Manual (ORA U 201 Sd)

• ORAU Environmental Services and Radiation TrainingQttaliry Program Manual (ORAU 2015c) The procedures contained in these manuals were developed to meet the requirements of U.S. Department of Energy (DOE) Order 414.lD and the U.S. Nuclear Regulatory Commission (NRC) Qttaliry Assttrance Manual for the Office of N ttclear Material S aftry and S efeg11ards and contain measures to assess processes during their performance. Humboldt Bay Confirmatory Survey Report C-1 5272-SR-01-0 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, NIST Radiochemistry Intercomparison Testing Program, and Intercomparison Testing Program Laboratory Quality Assurance Programs

• Training and certification of all individuals performing procedures

• Periodic internal and external audits Detectors used for assessing surface activity were calibrated in accordance with IS0-75031 recommendations. Total alpha and beta efficiencies (i::wraU were determined for each instrument/ detector combination and consisted of the product of the 27t instrument efficiency (i::;) and surface efficiency (i::,): EwraI = E; x i::,. ISO-7 503 recommends an s, of 0.25 for alpha emitters and also beta emitters with a maximum energy of less than 0.4 Me V and an s, of 0.5 for maximum beta energies greater than 0.4 MeV. Beta total efficiencies were determined based on a multi-point energy calibration using C-14, Tc-99, Tl-204, and Sr-90; development of instrument efficiency to beta energy calibration curves; and the selection of the E; and i::, that represented the primary radionuclide of concern. Based on the data in PG&E's FSSP worksheet, a weighted efficiency for the fractional contributions of Co-60 and Cs-137 was calculated. That total weighted efficiency was 0.25 for the plastic scintillators used to quantify beta surface activity. Th-230 was selected as the alpha calibration source. The 2n alpha instrument efficiency (s;) factor was 0.46 for the plastic scintillation detectors, resulting in a total efficiency of 0.11 C.3 SURVEY PROCEDURES C.3.1 SURFACE SCANS Scans for elevated gamma radiation were performed by passing the detector slowly over the surface. The distance between the detector and surface was maintained at a minimum. Specific scan 1 International Standard. ISO 7 503-1, fa'aluation of Surface Contamination -Part 1: Beta-emitters (maximum beta energy greater than 0.15 Me V) and alpha-emitters. August l, 1988. Humboldt Bay Confirmatory Survey Report C-2 5272-SR-01-0 minimum detectable concentration (MDCs) for the sodium iodide scintillation detectors (Nal) were not determined as the instruments were used solely as a qualitative means to identify elevated gamma radiation levels in excess of background. Identifications of elevated radiation levels that could exceed the site criteria were determined based on an increase in the audible signal from the indicating instrument. Beta scans were performed using small, hand-held scintillation detectors with a 1.2 mg cm2 window. Identification of elevated radiation levels was based on increases in the audible signal from the indicating instrument. Beta surface scan MDCs were estimated using the approach described in NUREG-1507. The scan MDC is a function of many variables, including the background level. Additional parameters selected for the calculation of scan MDCs included a two-second observation interval, a specified level of performance at the first scanning stage of 95% true positive and 25% false positive rate, which yields ad' value of 2.32 UREG-1507, Table 6.1), and a surveyor efficiency of 0.5. The beta total weighted efficiency factoring in the fractional contributions of Co-60 and Cs-137 was 0.25. The detector used had a general background of 305 cpm. The minimum detectable count rate (MDCR) and scan MDC was calculated as: C.3.2 Bi= (305)(2 s)(l min/60 s) = 10 counts MDCR = (2.32)(10 counts)112[(60 s/min)/2s) = 222 cpm MDCR.umror = 222/(0.5)112 = 314 cpm Scan MDC= (314)/(.25) = 1,257 dpm/100 cm2 SURFACE ACTIVITY MEASUREMENTS Measurements of total beta and alpha surface activity levels were performed using hand-held scintillation detectors coupled to portable ratemeter-scalers. Count rates (cpm), which were integrated over one minute with the detector held in a static position, were converted to activity levels (dpm/100 cm2) by dividing the count rate by the total static efficiency (EiXE,) and correcting for the physical area of the detector, which for both detectors is 100 cm2 ** ORAU did not determine construction material-specific background for each surface type encountered for determining net count rates. Instead, ORAU took the conservative approach followed by the licensee and reported gross activity values. However, should background subtraction be necessary, the ambient beta and alpha background (1 cpm) count rates for the area would be used (305 cpm used in the example below) when determining surface activity. An example a priori MDC for beta activity is given by: Humboldt Bay Confirmatory Survey Report C-3 5272-SR-01-0 MDC = 3 + ( 4.65v'B) G Etot \'{There: B background £tot total efficiency G geometry correction factor (1.0) The a priori beta static MDC was approximately 335 dpm/100 cm2 using the weighted efficiency calculated from the fractional contributions of Co-60 and Cs-137. C.3.3 SOIL SAMPLING Soil samples (approximately 0.5 kilogram each) were collected using a clean garden trowel, then transferred into a new sample container by ORAU personnel. In total, ORAU collected eight soil samples from the Discharge Canal during the July 20-23, 2015 confirmatory survey. ORAU personnel labeled each sample in accordance with ORAU survey procedures and completed the required custody documentation. C.4 RADIOLOGICAL ANALYSIS C.4.1 GAMMA SPECTROSCOPY Samples were analyzed as received, mixed, crushed, and/ or homogenized as necessary, and a portion sealed in a 0.5-liter Marinelli beaker. 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, high purity, 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 absorption peaks (TAPs) associated with the ROCs were reviewed for consistency of activity. Spectra were also reviewed for other identifiable TAPs. TAPs used for determining the activities of ROCs and the typical associated MDCs for a one-hour count time were: Radionuclide" TAP (MeV) MDC (pCi/g) Am-241 0.0595 0.15 Co-60 1.173 0.06 Cs-137 0.662 0.05 Humboldt Bay Confirmatory Survey Report C-4 5272-SR-01-0 Eu-152 0.344 0.10 Eu-154 0.723 0.15 b-94 0.871 0.05 Np-237 0.312 0.08 aspectra were also reviewed for other identifiable TAPs. C.4.2 DETECTION LIMITS Detection limits, referred to as MDCs, were based on 95% confidence level. 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. Humboldt Bay Confirmatory Survey Report C-5 5272-SR-01-0 APPENDIXD MAJOR INSTRUMENTATION Humboldt Bay Confirmatory Survey Report 5272-SR-01-0 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. D.1 SCANNING AND MEASUREMENT INSTRUMENT /DETECTOR COMBINATIONS D.1.1 GAMMA Ludlum NaI Scintillation Detector Model 44-10, Crystal: 5.1 cm x 5.1 cm (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Trimble Data Logger (Trimble Navigation Limited, Sunnyvale, California) D.1.2 BETA Ludlum Plastic Scintillation Detector Model 44-142, 100 cm2 physical area coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Trimble Data Logger (Trimble avigation Limited, Sunnyvale, California) D.1.3 ALPHA Ludlum Plastic Scintillation Detector Model 43-92, 100 cm2 physical area coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas) D.2 LABORATORY ANALYTICAL INSTRUMENTATION High-Purity, Extended Range Intrinsic Detector CANBERRA/Tennelec Model o: ERVDS30-25195 (Canberra, Meriden, Connecticut) Used in conjunction with: Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, Tennessee) and Multichannel Analyzer Canberra's Gamma Software Dell Workstation (Canberra, Meriden, Connecticut) Humboldt Bay Confirmatory Survey Report D-1 5272-SR-01-0 High-Purity, Intrinsic Detector Model No. GMX-45200-5 CANBERRA Model No: GC4020 (Canberra, Meriden, Connecticut) Used in conjunction with: Lead Shield Model G-11 Lead Shield Model SPG-16-K8 (Nuclear Data) Multichannel Analyzer Canberra's Gamma Software Dell Workstation (Canberra, Meriden, Connecticut) Low Background Gas Proportional Counter Model LB-5100-W (Tennelec/Canberra, Meriden, CT) Tri-Carb Liquid Scintillation Analyzer Model 3100 (Packard Instrument Co., Meriden, CT) Humboldt Bay Confirmatory Survey Report D-2 5272-SR-01-0