ML20021A128

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Letter from Erika Bailey, Oak Ridge Institute for Science and Education, to John Hickman, NRC, Forwarding Independent Confirmatory Survey Summary and Results for Remaining Land Areas and Select Buildings a the Humboldt Bay Power Plant, Eure
ML20021A128
Person / Time
Site: Humboldt Bay
Issue date: 01/17/2020
From: Bailey E, Engel K
Oak Ridge Institute for Science & Education
To: John Hickman
Division of Decommissioning, Uranium Recovery and Waste Programs
Hickman J
References
5272-SR-04-0, DE-SC0014664, RFTA No.18-005
Download: ML20021A128 (54)
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Text

January 17, 2020 Mr. John Hickman U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards Division of Decommissioning, Uranium Recovery, and Waste Programs Materials Decommissioning Branch TWFN Mail Stop: T-8F5 Rockville, MD 20852

SUBJECT:

DOE Contract No. DE-SC0014664 INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS AT THE HUMBOLDT BAY POWER PLANT, EUREKA, CALIFORNIA DOCKET NO.05000133; RFTA NO.18-005; DCN 5272-SR-04-0

Dear Mr. Hickman:

The Oak Ridge Institute for Science and Education (ORISE) is pleased to provide the enclosed report, which describes the procedures and results of the independent confirmatory survey for remaining land areas and select buildings at the Humboldt Bay Power Plant in Eureka, California that ORISE performed during the period of August 26-29, 2019. NRCs comments on the draft report have been addressed in this final version.

You may contact me at 865.576.6659 or Kaitlin Engel at 865.574.7008 if you have any questions or require additional information.

Sincerely, Erika N. Bailey Survey and Technical Projects Group Manager ORISE KME:tb electronic distribution: K. Conway, NRC R. Evans, NRC K. Engel, ORISE D. Hagemeyer, ORISE File/5272 100 ORAU Way

  • Oak Ridge
  • TN 37830
  • orise.orau.gov

INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS AT THE HUMBOLDT BAY POWER PLANT EUREKA, CALIFORNIA K. M. Engel ORISE FINAL REPORT Prepared for the U.S. Nuclear Regulatory Commission January 2020 Further dissemination authorized to NRC only; other requests shall be approved by the originating facility or higher NRC programmatic authority.

ORAU provides innovative scientific and technical solutions to advance research and education, protect public health and the environment and strengthen national security. Through specialized teams of experts, unique laboratory capabilities and access to a consortium of more than 100 major Ph.D.-granting institutions, ORAU works with federal, state, local and commercial customers to advance national priorities and serve the public interest. A 501(c) (3) nonprofit corporation and federal contractor, ORAU manages the Oak Ridge Institute for Science and Education (ORISE) for the U.S. Department of Energy (DOE). Learn more about ORAU at www.orau.org.

NOTICES The opinions expressed herein do not necessarily reflect the opinions of the sponsoring institutions of Oak Ridge Associated Universities.

This report was prepared as an account of work sponsored by the United States Government.

Neither the United States Government nor the U.S. Department of Energy, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe on privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement or recommendation, or favor by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.

INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS AT THE HUMBOLDT BAY POWER PLANT EUREKA, CALIFORNIA FINAL REPORT Prepared by K. M. Engel ORISE January 2020 Prepared for the U.S. Nuclear Regulatory Commission This document was prepared for U.S. Nuclear Regulatory Commission by the Oak Ridge Institute for Science and Education (ORISE) through interagency agreement number 31310018N0014 with the U.S. Department of Energy (DOE). ORISE is managed by Oak Ridge Associated Universities under DOE contract number DE-SC0014664.

Humboldt Bay Power Plant Confirmatory Survey Report 5272-SR-04-0

INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS FOR THE HUMBOLDT BAY POWER PLANT EUREKA, CALIFORNIA Prepared by: Date: 1/17/2020 K. M. Engel, Health Physicist ORISE Reviewed by: Date: 1/17/2020 P. H. Benton, Quality Manager ORISE Reviewed by: Date: 1/17/2020 N. A. Altic, CHP, Health Physicist ORISE Reviewed by: Date: 1/17/2020 W. F. Smith, Senior Chemist ORISE Reviewed and approved for release by: Date: 1/17/2020 E. N. Bailey, Survey and Technical Projects Group Manager ORISE FINAL REPORT January 2020 Humboldt Bay Power Plant Confirmatory Survey Report i 5272-SR-04-0

CONTENTS FIGURES .......................................................................................................................................................... iii TABLES ............................................................................................................................................................. iii ACRONYMS .................................................................................................................................................... iv EXECUTIVE

SUMMARY

.............................................................................................................................. v

1. INTRODUCTION....................................................................................................................................... 1
2. SITE DESCRIPTION ................................................................................................................................. 1
3. DATA QUALITY OBJECTIVES ............................................................................................................. 4 3.1 State the Problem .............................................................................................................................. 4 3.2 Identify the Decision ........................................................................................................................ 4 3.3 Identify Inputs to the Decision ....................................................................................................... 6 3.3.1 Radionuclides of Concern and Release Criteria ................................................................... 6 3.4 Define the Study Boundaries ........................................................................................................... 7 3.5 Develop a Decision Rule.................................................................................................................. 8 3.6 Specify Limits on Decision Errors ................................................................................................. 9 3.7 Optimize the Design for Obtaining Data...................................................................................... 9
4. PROCEDURES ..........................................................................................................................................10 4.1 Reference System ............................................................................................................................10 4.2 Surface Scans....................................................................................................................................10 4.3 Surface Activity Measurements .....................................................................................................11 4.4 Soil Sampling....................................................................................................................................11
5. SAMPLE ANALYSIS AND DATA INTERPRETATION ...............................................................12
6. FINDINGS AND RESULTS ...................................................................................................................13 6.1 Surface Scans....................................................................................................................................13 6.2 Surface Activity Measurements .....................................................................................................16 6.3 Gamma Radiation Measurements and Soil Sampling ................................................................16
7.

SUMMARY

..................................................................................................................................................17

8. REFERENCES ...........................................................................................................................................19 APPENDIX A: FIGURES APPENDIX B: DATA TABLES APPENDIX C: MAJOR INSTRUMENTATION APPENDIX D: SURVEY AND ANALYTICAL PROCEDURES Humboldt Bay Power Plant Confirmatory Survey Report ii 5272-SR-04-0

FIGURES Figure 2.1. HBPP Aerial View ......................................................................................................................... 2 Figure 2.2. Backfilled Survey Units ................................................................................................................. 3 Figure 2.3. Survey Units FSS Classification ................................................................................................... 3 Figure 6.1. Q-Q Plots of WMF Scan Data...................................................................................................14 Figure 6.2. Q-Q Plots of Security Building Scan Data ...............................................................................15 Figure 6.3. Q-Q Plots of Soil Lab Scan Data ..............................................................................................15 TABLES Table 3.1. HBPP Confirmatory Survey Decision Process ........................................................................... 5 Table 3.2. HBPP Soil DCGLWs ....................................................................................................................... 6 Table 3.3. HBPP Surface Activity DCGLWs .................................................................................................. 7 Table 3.4. HBPP Investigation Levels ........................................................................................................... 9 Table 6.1. Summary of Scan Results .............................................................................................................14 Table 6.2. Summary of Surface Activity Results .........................................................................................16 Table 6.3. Summary of Soil Sampling Direct Measurements ....................................................................16 Table 6.4. Summary of Soil Sample Concentrations ..................................................................................17 Humboldt Bay Power Plant Confirmatory Survey Report iii 5272-SR-04-0

ACRONYMS AA alternative action AEC Atomic Energy Commission cm centimeter cpm counts per minute DCGLW derived concentration guideline levels dpm/100 cm2 disintegrations per minute per 100 square centimeters DQO data quality objective FSS final status survey GPS global positioning system HBPP Humboldt Bay Power Plant HTD hard-to-detect MDC minimum detectable concentration mg/cm2 milligram per square centimeter mrem/yr millirem per year NaI[Tl] thallium-doped sodium iodide NORM naturally occurring radioactive material NRC U.S. Nuclear Regulatory Commission ORISE Oak Ridge Institute for Science and Education pCi/g picocurie per gram PG&E Pacific Gas & Electric PSQ principal study question Q-Q quantile-quantile ROC radionuclide of concern SAFSTOR safe storage SOF sum-of-fractions SU survey unit VSP Visual Sample Plan WMF waste management facility Humboldt Bay Power Plant Confirmatory Survey Report iv 5272-SR-04-0

INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS AT THE HUMBOLDT BAY POWER PLANT EUREKA, CALIFORNIA EXECUTIVE

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) requested that the Oak Ridge Institute for Science and Education (ORISE) perform an independent confirmatory survey of the remaining land areas and select buildings at the Humboldt Bay Power Plant in Eureka, California. ORISE performed independent assessment activities during the period of August 26-29, 2019. Confirmatory survey activities included gamma surface scans, gamma direct measurements, alpha-plus-beta scans, alpha-only and beta-only direct measurements, smear sampling, and soil sampling within the land areas and select buildings, as applicable.

No elevated direct gamma radiation levels distinguishable from background were identified in any of the land areas surveyed. In total, 20 surface soil samples were collected for analysis: eight random and two judgmental samples from areas believed to be mostly native soil and ten of the licensees archived final status survey (FSS) surface soil samples from areas where the sites staff had confirmed backfill material had been applied. The radionuclide concentrations in the soil samples were compared to the NRC-approved derived concentration guidelines (DCGLWs) established for the site. All radionuclide concentrations were below the DCGLWs and all sum-of-fractions were less than 1. Additionally, all radionuclide concentrations were less than 50% of the respective gamma-emitting DCGLWs, thus confirming the licensees FSS classification.

Limited confirmatory survey activities were conducted in three buildings during this survey: the security building (Building 7), the Waste Management Facility (WMF), and the soil lab (Building 13).

Gamma and alpha-plus-beta scans were performed in interior portions of all three buildings.

Additionally, the roof of the security building and the asphalt/concrete pad north and east of the WMF were scanned for gamma radiation. Elevated gamma radiation was identified within the soil lab, where the sites radiological sources were stored. Judgmental direct measurements and smear samples were collected behind the push walls in the WMF. Total activities measured in the WMF did not exceed the DCGLWs and the removable activity was less than ten percent of the total activity. Therefore, confirmatory direct measurements support the licensees Class 2 FSS SU designation.

Humboldt Bay Power Plant Confirmatory Survey Report v 5272-SR-04-0

The confirmatory results indicate that the residual radioactivity concentrations in the remaining land areas and structural surfaces were below the applicable release criteria, and the confirmatory results support the licensees classification of the FSS SUs. The confirmatory survey results indicate that the areas surveyed meet the NRC-approved criteria for release for unrestricted use. Such conclusions cannot be drawn about the soil lab at this time as radioactive materials (i.e., sources) were still present during the confirmatory survey.

Humboldt Bay Power Plant Confirmatory Survey Report vi 5272-SR-04-0

INDEPENDENT CONFIRMATORY SURVEY

SUMMARY

AND RESULTS FOR REMAINING LAND AREAS AND SELECT BUILDINGS 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 the Atomic Energy Commission (AEC) provisional license number DPR-7. HBPP Unit 3 achieved initial criticality in February 1963 and began 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 reactor startup until cladding failures resulted in plant system contamination - zircaloy-clad fuel was used exclusively starting in 1965, eliminating cladding-related contamination. A number of spill 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 modification. 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 of 1983 to decommission Unit 3, received a possession-only license amendment, and placed the unit into cold shutdown and safe storage (SAFSTOR). The impacted areas associated with Unit 3 have gone through decommissioning. As part of the Humboldt Bay Repowering Project, PG&E has built ten new fossil fuel units, 16.3 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 structures removed to ground level (Bartlett 2011).

The U.S. Nuclear Regulatory Commission (NRC) requested that the Oak Ridge Institute for Science and Education (ORISE) perform confirmatory survey activities of the HBPP. The focus of this survey effortas determined by NRC staffwas on the remaining land areas and three buildings:

the security building (Building 7), soil lab (Building 13), and the Waste Management Facility (WMF).

2. SITE DESCRIPTION The HBPP site, owned by PG&E consists of 58 hectares on the southern edge of Humboldt Bay, 6 kilometers southwest of the town of Eureka in Humboldt County, California. Figure 2.1 provides a recent aerial view of the HBPP.

Humboldt Bay Power Plant Confirmatory Survey Report 1 5272-SR-04-0

Figure 2.1. HBPP Aerial View Most buildings have been demolished and many roadways and parking lots have been removed. The survey units (SUs) were backfilled anywhere from 1 to 100% with onsite recycled soil from all three final status survey (FSS) classifications of material (MARSSIM class 1, 2, or 3). After backfilling with onsite soils was complete, the SUs were then covered with off-site material or engineered materials to various depths (ORAU 2019c). Figure 2.2 indicates the SUs that received some amount of backfill materialseither from onsite or offsite borrowand Figure 2.3 shows the final status survey (FSS) classification of the SUs.

The three buildings selected for confirmatory surveys were the WMF, security building (Building 7),

and soil lab (Building 13). The WMF was undergoing FSS during the onsite confirmatory survey activities while the security building and soil lab had not yet received FSS.

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Figure 2.2. Backfilled Survey Units Figure 2.3. Survey Units FSS Classification Humboldt Bay Power Plant Confirmatory Survey Report 3 5272-SR-04-0

3. DATA QUALITY OBJECTIVES The data quality objectives (DQOs) described herein are consistent with the Guidance on Systematic Planning Using the Data Quality Objectives Process (EPA 2006) and provide a formalized method for planning radiation surveys, improving survey efficiency and effectiveness, and ensuring that the type, quality, and quantity of data collected are adequate for the intended decision applications. The seven steps in the DQO process are as follows:
1. State the problem
2. Identify the decision
3. Identify inputs to the decision
4. Define the study boundaries
5. Develop a decision rule
6. Specify limits on decision errors
7. Optimize the design for obtaining data 3.1 STATE THE PROBLEM The first step in the DQO process defined the problem that necessitated the study, identified the planning team, and examined the project budget and schedule. The planning team, project budget, and schedule are presented in the project-specific plan and are not repeated here (ORISE 2016).

NRC staff requested that ORISE perform confirmatory survey activities at the HBPP. The objective of the confirmatory activities was to generate independent radiological data to assist NRC staff in evaluating the licensees FSS results. The problem statement was as follows:

Confirmatory surveys are necessary to generate independent radiological data to assist the NRC staff with their assessment and determination of the adequacy of the FSS design, implementation, and results for demonstrating compliance with the release criteria.

3.2 IDENTIFY THE DECISION The second step in the DQO process identified the principal study questions (PSQs) and alternative actions (AAs), developed decision statements (DSs), and organized multiple decisions, as Humboldt Bay Power Plant Confirmatory Survey Report 4 5272-SR-04-0

appropriate. This was done by specifying AAs that could result from a yes response to the PSQs and combining the PSQs and AAs into DSs. Table 3.1 presents the PSQs, AAs, and DSs.

Table 3.1. HBPP Confirmatory Survey Decision Process Principal Study Questions Alternative Actions Yes:

Compile confirmatory data and report results to NRC staff for their decision making. Provide independent interpretation that confirmatory field surveys did not identify anomalous areas of residual radioactivity and that quantative field and laboratory data satisfied the NRC-PSQ1: Are residual radioactivity concentrations approved decommissioning criteria.

in the remaining land areas or structural surfaces below applicable release criteria? No:

Compile confirmatory data and report results to NRC staff for their decision making. Provide independent interpretation of confirmatory survey results identifying any anomalous field or laboratory data for NRC staffs determination of the adequacy and accuracy of the FSS data.

Yes:

Confirmatory results support the classification of the FSS SUs. Compile confirmatory survey data and present results to NRC staff for their decision making.

PSQ2: Do the confirmatory results support the MARSSIM classification of the FSS SUs? No:

Confirmatory results do not support the classification of the FSS SUs. Summarize the discrepancies and provide technical comments to NRC staff for their decision making.

Decision Statements Determine if anomalous confirmatory survey results (i.e., volumetric concentrations and/or surface activity levels) exceed the NRC-approved decommissioning criteria.

Determine if confirmatory survey results support the FSS SU classification as outlined in MARSSIM guidance classification.

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3.3 IDENTIFY INPUTS TO THE DECISION The third step in the DQO process identified both the information needed and the sources of this information, determined the basis for action levels, and identified sampling and analytical methods to meet data requirements. For this effort, information inputs included the following:

  • HBPP characterization data
  • HBPP Geographic Information System and Visual Sample Plan (VSP) files, for SU boundaries
  • HBPPs FSS data and supporting documentation (Note that, at the time of the confirmatory survey, the FSS was still in progress for the WMF and FSS had not started for the security building or soil lab)
  • ORISE gamma walkover surveys
  • ORISE volumetric sample analytical results for soil
  • ORISE static direct measurements and removable activity results
  • Radionuclides of concern (ROCs) and their associated limits (discussed in Section 3.3.1) 3.3.1 Radionuclides of Concern and Release Criteria The primary ROCs identified for the HBPP are beta-gamma emittersfission and activation products resulting from reactor operation. The HBPP derived concentration guideline levels (DCGLWs) for soils and structural surfaces are presented in Table 3.2 and Table 3.3, respectively (PG&E 2014).

Table 3.2. HBPP Soil DCGLWs DCGLW DCGLW DCGLW ROC ROC ROC (pCi/g)a (pCi/g) (pCi/g)

Am-241 25 Cs-137 7.9 Np-237 1.1 C-14 6.3 Eu-152 10 Pu-238 29 Cm-243 29 Eu-154 9.4 Pu-239 26 Cm-244 48 H-3 680 Pu-240 26 Cm-245 17 Nb-94 7.1 Pu-241 860 Cm-246 25 Ni-59 1,900 Sr-90 1.5 Co-60 3.8 Ni-63 720 Tc-99 12 a pCi/g = picocurie per gram Humboldt Bay Power Plant Confirmatory Survey Report 6 5272-SR-04-0

Table 3.3. HBPP Surface Activity DCGLWs DCGLW DCGLW DCGLW ROC ROC ROC (dpm/100 cm2)a (dpm/100 cm2) (dpm/100 cm2)

Am-241 3.00E+03 Cs-137 4.60E+04 Np-237 2.40E+03 C-14 7.00E+06 Eu-152 2.70E+04 Pu-238 3.40E+03 Cm-243 4.30E+03 Eu-154 2.50E+04 Pu-239 3.10E+03 Cm-244 5.50E+03 H-3 1.80E+08 Pu-240 3.10E+03 Cm-245 2.20E+03 Nb-94 1.90E+04 Pu-241 1.40E+05 Cm-246 2.70E+03 Ni-59 6.30E+07 Sr-90 9.70E+04 Co-60 1.30E+04 Ni-63 2.40E+07 Tc-99 9.60E+06 a dpm/100 cm2 = disintegrations per minute per 100 square centimeters Each radionuclide-specific DCGLW value in Tables 3.2 and 3.3 represents the surficial concentration of individual radionuclides that would be deemed in compliance with the 25 millirem per year (mrem/yr) unrestricted release dose limit to the average member of the critical group. Therefore, for sites with multiple radionuclides present, radionuclide-specific results (i.e., volumetric samples) must be evaluated using the sum-of-fractions (SOF) approach to assess the total dose and demonstrate compliance with the dose limit. SOF calculations are performed as follows:

=0 =0 Where Cj is the concentration of the ROC j and DCGLW,j is the DCGLW for ROC j. Note that gross concentrations are considered for conservatism. A SU, where the average ROC concentration does not exceed 1 (unity), ensures compliance with the 25 mrem/yr unrestricted release dose limit.

Elevated measurement comparisons were not necessary, and thus, not considered as part of this study.

3.4 DEFINE THE STUDY BOUNDARIES The fourth step in the DQO process defined target populations and spatial boundaries, determined the timeframe for collecting data and making decisions, addressed practical constraints, and determined the smallest subpopulations, area, volume, and time for which separate decisions must be made.

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The areas of focus for this survey were the safely accessible Class 1, 2, and 3 land areas depicted in Figure 2.3 as well as three buildings: WMF, security building (Building 7), and soil lab (Building 13).

Temporal boundaries to complete this survey were limited to four 10-hour days on-site during the week of August 26-29, 2019.

3.5 DEVELOP A DECISION RULE The fifth step in the DQO process specified appropriate parameters (e.g., mean, median), confirmed action levels were above detection limits, and developed an ifthen decision rule statement.

Decision rules for this survey focused on independent surface scanning surveys and sample results to identify locations that could exceed the applicable DCGLWs and/or analytical minimum detectable concentrations (MDCs).

The confirmatory survey design for the land areas focused on generating an unbiased estimate of the site mean ROC concentration for direct comparison against the DCGLWs and scanning to identify potential hot spots. For this survey effort, the parameter of interest was the mean SOF for the land area along with the ROC concentrations of individual samples. Individual sample results were compared directly to the DCGLWs. The decision rules can be stated as:

If the mean SOF, as determined by ORISE, and individual sample results are less than the DCGLWs then recommend acceptance. If results are above the DCGLWs, then perform further evaluations and provide technical comments/recommendations.

SU classifications were also assessed as part of the confirmatory process based on the requirements outlined in the LTP. Confirmatory investigations were focused on Class 2 and 3 SUs, as well as non-impacted areas, because a Class 1 SU will not receive higher classification. FSS investigation levels that trigger additional evaluations were established and are presented in Section 5.3.6.2 of the LTP.

These investigation levels are reproduced in Table 3.4. During the confirmatory surveys, ORISE focused on identifying locations that could potentially exceed the soil sample investigation levels.

These locations were used to confirm whether the SU should have been reclassified as part of the FSS process. The decision rule related to SU classification was stated as follows:

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If soil concentrations or surface activity results indicate that a Class 2 or Class 3 area should be reclassified to a higher classification, then summarize confirmatory data for NRC staffs evaluation and decision making.

Table 3.4. HBPP Investigation Levels a SU Classification Scan Investigation Levels Direct Investigation Levels

> DCGLEMC or > DCGLW and > a Class 1 > DCGLEMC b statistical parameter-based value

> DCGLW or > MDCScan if Class 2 > DCGLW MDCScan is greater than DCGLW c Class 3 Detectable over background > 0.5

  • DCGLW a Recreated from PG&E 2014 b DCGLEMC = derived concentration guideline level elevated measurement comparison c MDC Scan = scan minimum detectable concentration 3.6 SPECIFY LIMITS ON DECISION ERRORS The sixth step in the DQO process established bounds of decision errors. Decision errors were controlled by optimizing the confirmatory field measurement and laboratory analytical MDCs.

One order of control was the allowable uncertainty in the estimated mean. The soil sample size was sufficient to estimate the mean SOF within 0.2 of the true mean at the 95% confidence level. The assumed standard deviation was 0.4, which is conservative, to reduce the probability of underestimating the site ROC variability. Any anomalies identified while performing surveys or following data assessment were fully investigated and discussed with NRC staff.

A second order of control was to optimize the MDCs of analyses performed by ORISE, both for field and laboratory measurements. Nominal scan and analytical MDCs for select ROCs are presented in Appendix D.

3.7 OPTIMIZE THE DESIGN FOR OBTAINING DATA The seventh step in the DQO process was used to review the DQO outputs; develop data collection design alternatives, formulate mathematical expressions for each design, select the sample size to satisfy DQOs, decide on the most resource-effective design of agreed alternatives, and document Humboldt Bay Power Plant Confirmatory Survey Report 9 5272-SR-04-0

requisite details. Survey design and laboratory analyses were optimized by implementing the procedures presented in Sections 4 and 5, respectively.

4. PROCEDURES The confirmatory survey activities, conducted during the period of August 26-29, 2019, were in accordance with the project-specific confirmatory survey plan, the ORAU Radiological and Environmental Survey Procedure Manual, and the ORAU Environmental Services and Radiation Training Quality Program Manual (ORISE 2016, ORAU 2016a, 2019a). Appendices C and D provide additional information regarding survey instrumentation and related processes discussed within this section.

4.1 REFERENCE SYSTEM ORISE referenced confirmatory measurement/sampling locations to global positioning system (GPS) coordinates, specifically NAD 1983 (CORS96) State Plane California Zone 1. Other prominent site features also were referenced. Measurement and sampling locations were documented on detailed survey maps.

4.2 SURFACE SCANS Surface scans of land areas were performed with Ludlum model 44-10 5.48-centimeter (cm) by 5.48-cm thallium-doped sodium iodide (NaI[Tl]) scintillation detectors coupled to Ludlum Model 2221 ratemeter-scalers with audible indicators. Detectors were also coupled to GPS data logging systems that enabled real-time gamma count rate and spatial data capture. Low- to medium-density surface scans were performed within select SUs, as time and access permitted. Total scan coverage was dependent on accessibility as many areas were impassable due to thick grass or standing water.

Many areas of the site had been backfilled and covered with offsite top soil as mentioned previously in Section 2.

Surface scans of structures were performed with NaI(Tl)s and either Ludlum model 43-68 gas-flow proportional hand-held detectors or Ludlum model 43-37 gas-flow proportional floor monitors with 0.8 milligram per square centimeter (mg/cm2) thick Mylar windows operated in alpha-plus-beta mode. Both detector types were coupled to Ludlum model 2221 ratemeter-scalers with audible indicators. Detectors were also coupled to data loggers to electronically record all scanning data Humboldt Bay Power Plant Confirmatory Survey Report 10 5272-SR-04-0

points. Scans with the floor monitor were qualitative (scan MDCs not calculated), but ORISE experience is that floor monitors are efficient at identifying low levels of surface contamination that can be quantitatively investigated using other hand-held instruments.

As noted in Section 6.3 of the NRC-approved 2016 Confirmatory Survey Plan (ORISE 2016), direct measurements for total beta and alpha activity would, at a minimum, be collected from judgmentally selected locations based on surface scans. The total number of direct measurements was dependent on findings as the survey progressed. No areas were marked for further investigation based on scanning results.

4.3 SURFACE ACTIVITY MEASUREMENTS Total surface activity measurements were performed with Ludlum model 43-68 gas-flow proportional hand-held detectors coupled to Ludlum model 2221 ratemeter-scalers with audible output. The Mylar thickness was 0.8 mg/cm2 for alpha-only measurements, and 3.8 mg/cm2 thickness for beta-only measurements.

Although scans of the floors and walls in the WMF behind the north and south push walls did not indicate elevated radiation levels of concern, nine direct measurements for total alpha and beta activity were collected from judgmentally selected areas based on the concern for accumulation potential behind the walls. No direct measurements were collected in the main area of the WMF, security building, or the soil lab based on scanning results.

Smear samples, to determine removable alpha and beta activity levels, were collected from all direct measurement locations. Smears for hard-to-detects (HTDs), H-3, C-14, and Ni-63, were judgmentally collected at two locations within the WMF, co-located with the alpha and beta smear sample.

4.4 SOIL SAMPLING Eighteen random soil samples and two judgmental soil samples were collected from the land area SUs. Visual Sample Plan (VSP) version 7.10 was used to determine the number of samples required to estimate the mean ROC concentration within the study area. For this effort, based on the allowable uncertainty in the mean, presented in Section 3.6, 18 random samples were required.

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A total of 20 confirmatory soil samples were collected18 from randomly selected locations and 2 from judgmentally selected locations. Of the eighteen random samples, eight were from areas that had not been backfilled on the eastern and western sides of the property. The other ten random samples were from the sites archived samples that were collected from native soil before backfill, as requested by the NRC. The sites sample that was closest to the ORISE randomly generated location was selected for analysis. Two judgmental samples were selected from non-backfilled areas, per the request of NRC staff.

Surface soil samples were collected from a depth of 0-15 cm using hand trowels. Gamma measurements were performed prior to and after sample collection to assess the potential for subsurface contamination. No subsurface samples were collected. Sampling equipment was rinsed and wiped after each sample to minimize the potential for cross-contamination.

5. SAMPLE ANALYSIS AND DATA INTERPRETATION Samples and data collected on site were transferred to the ORISE facility for analysis and interpretation. Sample custody was transferred to the Radiological and Environmental Analytical Laboratory in Oak Ridge, Tennessee. Sample analyses were performed in accordance with the ORAU Radiological and Environmental Analytical Laboratory Procedures Manual (ORAU 2019b).

A wet aliquot of each soil sample was first set aside for further analyses of HTDs, if needed. The remaining portions of the soil samples were dried and homogenized before being analyzed via gamma spectrometry for gamma-emitting fission and activation products. The spectra also were reviewed for other identifiable photopeaks. Based on the results of the gamma spectroscopy and as directed by NRC staff, further analyses were not performed. Analytical results are reported in units of picocuries per gram (pCi/g).

Smear samples were analyzed for alpha and beta activity using a low-background proportional counter. Smears for HTDs, H-3 and C-14, were analyzed via liquid scintillation counting. Smear samples and direct measurement results are reported in units of disintegrations per minute per one hundred square centimeters (dpm/100 cm2).

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Direct measurements are gross and background contributions were not subtracted, which is consistent with the sites reporting and is conservative. Gamma radiation scan and static measurements are presented as gross counts per minute (cpm).

Scan data sets were graphed in a quantile-quantile (Q-Q) plot for assessment. The Q-Q plot is a graphical tool for assessing the distribution of a data set. For the scan data, the Y-axis represents gross gamma surface activity in units of cpm. The X-axis represents the data quantiles about the median value. Values less than the median are represented in the negative quantiles, and values greater than the median are represented in the positive quantiles. A normal distribution that is not skewed by outliers will appear as a straight line, with the slope of the line subject to the degree of variability among the data population. More than one distribution, such as background plus contamination or other outliers, will appear as a step function. Q-Q plots for the data are presented in Section 6.

6. FINDINGS AND RESULTS The results of the confirmatory survey are discussed in the following subsections.

Appendix A provides the figures generated from the survey data, Appendix B provides data tables, and Appendices C and D provide additional details regarding field and laboratory instrumentation as well as additional information on calibration, quality assurance, survey and analytical procedures, and detection sensitivities.

6.1 SURFACE SCANS Table 6.1 provides a summary of the scanning survey data collected at HBPP during the August 2019 survey activities.

Humboldt Bay Power Plant Confirmatory Survey Report 13 5272-SR-04-0

Table 6.1. Summary of Scan Results Scan Ranges (cpm)

Area Gamma Alpha-plus-Beta Alpha-plus-Beta Lower Walls and Floors Lower Walls Floors Land Areas 3,200 to 8,800 --a --

WMF 2,900 to 6,500 6 to 590 320 to 1,200 WMF Pad 3,300 to 6,000 -- 700 to 1,800 Security Building 5,700 to 7,700 76 to 620 480 to 1,200 Security Building Roof 2,400 to 6,700 -- --

Soil Lab 3,100 to 13,000 44 to 530 340 to 1,100 a data not collected A gamma walkover map of all of the land areas surveyed, the security building roof, and the WMF pad are provided in Appendix A. No elevated areas were identified in the land areas, security building roof, or WMF pad surveys. Q-Q plots for the scan data from inside the three buildings are shown in Figures 6.1 through 6.3. For most of the scan data, the Q-Q plots show a straight line indicating a normal distribution which is expected for background conditions. Gamma scans in the soil lab, however, do not indicate background conditions as there is a sharp increase in the right tail. This was due to the presence of sealed sources stored within the soil lab during the time of the survey.

Figure 6.1. Q-Q Plots of WMF Scan Data Humboldt Bay Power Plant Confirmatory Survey Report 14 5272-SR-04-0

Figure 6.2. Q-Q Plots of Security Building Scan Data Figure 6.3. Q-Q Plots of Soil Lab Scan Data Humboldt Bay Power Plant Confirmatory Survey Report 15 5272-SR-04-0

6.2 SURFACE ACTIVITY MEASUREMENTS Table 6.2 provides a summary of the surface activity measurements collected within the WMF.

Full data tables can be found in Appendix B. In total nine locations were selected for direct measurements and smear sampling. The confirmatory data were compared against the investigation levels presented in Table 3.4. All total activity measurements were below the DCGLWs, thus confirming the Class 2 FSS SU classification. All removable activity was less than 10% of the total activity.

Table 6.2. Summary of Surface Activity Resultsa Total Activity Removable Activity Area Alpha Beta Alpha Beta H-3 C-14 dpm/100 cm2 dpm/100 cm2 1,200 to WMF 10 to 50 0b 0 to 3 -7 to -2 -4 to 1 1,800 a Zeros due to rounding.

bAll nine values were 0 dpm/100 cm2 6.3 GAMMA RADIATION MEASUREMENTS AND SOIL SAMPLING Soil sampling locations are displayed in Appendix A. Table 6.3 provides a summary of the NaI(Tl) direct measurements collected pre- and post-sample. Table 6.4 provides a summary of the radionuclide concentrations. Appendix B provides individual sample results.

Table 6.3. Summary of Soil Sampling Direct Measurements No. of Gamma Measurement (cpm)

Sample Type Samples Pre-Sample Post-Sample ORISE Random 8 3,500 to 5,000 3,500 to 5,700 ORISE Judgmental 2 3,700 to 5,400 5,100 to 5,600 Archived FSS Random 10 -- a to -- -- to --

a Pre- and post-sample gamma measurements not provided.

Humboldt Bay Power Plant Confirmatory Survey Report 16 5272-SR-04-0

Table 6.4. Summary of Soil Sample Concentrationsa ORISE Random ORISE Judgmental FSS Samples ROC b Min Max Min Max Min Max pCi/g Am-241 -0.10 -0.004 -0.023 0.050 -0.083 0.021 Cm-245 -0.06 0.7 0.00 0.06 -0.082 0.11 Co-60 -0.09 0.040 -0.027 0.016 -0.022 0.012 Cs-137 0.010 0.429 0.077 0.132 -0.013 0.058 Eu-152 -0.12 0.14 -0.010 0.035 -0.050 0.029 Eu-154 -0.38 0.2 -0.146 0.001 -0.36 -0.048 Nb-94 -0.06 0.005 0.009 0.013 -0.005 0.015 Np-237 by Pa-233 -0.23 0.012 0.036 0.042 -0.008 0.013 SOF 0.003 0.104 0.056 0.058 0.002 0.015 a Zeros due to rounding.

b Only these gamma emitting ROCs were used in the ORISE SOF calculations.

None of the individual ROC concentrations exceeded the DCGLWs and all SOF results were less than 1. The confirmatory data were compared against the investigation levels presented in Table 3.4.

None of the ROC concentrations exceeded 50% of the respective gamma-emitting DCGLWs, thus confirming the licensees FSS SU classifications.

7.

SUMMARY

At the NRCs request, ORISE conducted confirmatory survey activities at the HBPP during the period of August 26-29, 2019. Confirmatory survey activities included gamma walkover scans, gamma direct measurements, and soil sampling in the accessible land areas and alpha-plus-beta scans, alpha only and beta only direct measurements, and smear sampling in select buildings.

No elevated direct gamma radiation levels above localized background were identified in any of the land areas surveyed. In total, 20 soil samples were collected for laboratory analysis: eight random and two judgmental samples from areas thought to be native soil and ten archived samples from areas before backfill. The radionuclide concentrations in the soil samples were compared to the NRC approved DCGLWs established for the site. All concentrations were below the DCGLWs and all Humboldt Bay Power Plant Confirmatory Survey Report 17 5272-SR-04-0

sum-of-fractions results were less than 1. For all samples, the ROC concentrations were less than 50% of the respective gamma-emitting DCGLWs, thus confirming the licensees FSS classification.

Three buildings were also limitedly investigated during this survey: the security building (Building 7),

the WMF, and the soil lab (Building 13). A portion of the interior of all the buildings and additionally, the roof of the security building and the asphalt/concrete pad north and east of the WMF were scanned. Only the area where the sites sources were stored within the soil lab was identified with elevated gamma radiation levels. Judgmental direct measurements and smear samples were collected behind the push walls in the WMF. Total activities measured in the WMF did not exceed the DCGLWs and the removable activity was less than ten percent of the total activity, thus confirming the licensees Class 2 FSS SU classification.

The confirmatory results indicate that the residual radioactivity concentrations in the remaining land areas and structural surfaces were below the applicable release criteria, and the confirmatory results support the licensees classification of the FSS SUs. The confirmatory results indicate that the areas surveyed meet the NRC-approved criteria for release for unrestricted use. Such conclusions cannot be drawn about the soil lab at this time as radioactive materials (i.e., sources) were still present during the confirmatory survey.

Humboldt Bay Power Plant Confirmatory Survey Report 18 5272-SR-04-0

8. REFERENCES Bartlett 2011. Historical Site Assessment 2011 Update, prepared for Humboldt Bay Power Plant Pacific Gas & Electric Company, Eureka, California. Bartlett Nuclear Incorporated. Plymouth, Massachusetts. July.

EPA 2006. Guidance on Systematic Planning Using the Data Quality Objectives Process. EPA QA/G-4.

U.S. Environmental Protection Agency. Washington, D.C. February.

ESI 2008. Historical Site Assessment, prepared for the Humboldt Bay Power Plant Pacific Gas &

Electric Company, Eureka, California, Draft. September.

NRC 1998. Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions. NUREG-1507. U.S. Nuclear Regulatory Commission.

Washington, D.C. June.

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

ORAU 2016a. ORAU Radiological and Environmental Survey Procedures Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. November 10.

ORAU 2016b. ORAU Health and Safety Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. January.

ORAU 2019a. ORAU Environmental Services and Radiation Training Quality Program Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. July 20.

ORAU 2019b. ORAU Radiological and Environmental Analytical Laboratory Procedures Manual. Oak Ridge Associated Universities. Oak Ridge, Tennessee. June 27.

ORAU 2019c. Email exchange between Erika Bailey/Oak Ridge Associated Universities and Marshall Blake/Pacific Gas & Electric. August 21.

ORISE 2016. Project-Specific Plan for the Confirmatory Survey Activities at the Humboldt Bay Power Plant; Eureka, California. Oak Ridge Institute for Science and Education. Oak Ridge, Tennessee.

August 3.

PG&E 2014. Humboldt Bay Power Plant, Unit 3 License Termination Plan, Rev. 1. Pacific Gas & Electric Company. Avila Beach, California. August 13.

PG&E 2019. Final Status Survey Planning (FSSP) Worksheet. Attachment 9.1. Rev. 2D. Pacific Gas &

Electric Company. Avila Beach, California. July 12.

Humboldt Bay Power Plant Confirmatory Survey Report 19 5272-SR-04-0

APPENDIX A: FIGURES Humboldt Bay Power Plant Confirmatory Survey Report 5272-SR-04-0

Figure A.1. Western Side of Site Gamma Walkover Data Humboldt Bay Power Plant Confirmatory Survey Report A-1 5272-SR-04-0

Figure A.2. Eastern Side of Site Gamma Walkover Data Humboldt Bay Power Plant Confirmatory Survey Report A-2 5272-SR-04-0

Figure A.3. Security Building Roof Gamma Walkover Data Humboldt Bay Power Plant Confirmatory Survey Report A-3 5272-SR-04-0

Figure A.4. WMF Pad Gamma Walkover Data Humboldt Bay Power Plant Confirmatory Survey Report A-4 5272-SR-04-0

Figure A.5. WMF Pad Alpha-plus-Beta Walkover Data Humboldt Bay Power Plant Confirmatory Survey Report A-5 5272-SR-04-0

Figure A.6. Soil Sample Locations Humboldt Bay Power Plant Confirmatory Survey Report A-6 5272-SR-04-0

Figure A.7. WMF Direct Measurement and Smear Sampling Locations Humboldt Bay Power Plant Confirmatory Survey Report A-7 5272-SR-04-0

APPENDIX B: DATA TABLES Humboldt Bay Power Plant Confirmatory Survey Report 5272-SR-04-0

Table B.1. Soil Sample Locations and Gamma Measurements Gamma Coordinates (ft)

Sample ID (cpm)

Easting Northing Pre- Post-Random Locations ORISE 5272S0024 5948288 2161054 5,000 5,500 ORISE 5272S0025 5947703 2161509 3,600 4,100 ORISE 5272S0026 5947897 2161303 4,400 4,800 ORISE 5272S0028 5950292 2161514 3,500 3,500 ORISE 5272S0029 5950679 2161710 3,700 4,200 ORISE 5272S0030 5950407 2161732 4,400 4,900 ORISE 5272S0031 5950482 2161758 4,900 5,700 ORISE 5272S0032 5950140 2161278 4,800 5,300 Archived FSS FSS-2377: OOL10-20-005-F 5948629 2160869 -- --

Archived FSS 2012-003: HBPP-CHAR-OOL10-05-Ca 5949079 2160855 -- --

Archived FSS FSS-2154: OOL10-25-003-F-RC 5949019 5121046 -- --

Archived FSS FSS-1857: OOL10-25-007-F 5949120 2161264 -- --

Archived FSS FSS-0694: NOL01-03-01-106-F-RC 5949366 2161272 -- --

Archived FSS FSS-0519: OOL01-03-011-F-RC 5949628 2161279 -- --

Archived FSS FSS-1707: OOL09-02-004-F 5949885 2161269 -- --

Archived FSS FSS-2190: OOL07-03-120-F 5949504 2161518 -- --

Archived FSS FSS-2057: OOL09-07-020-F 5949752 2161494 -- --

Archived FSS FSS-1589: OOL09-06-003-F-RC 5950018 2161501 -- --

Judgmental Locations ORISE 5272S0027 5948353 2161310 3,700 5,100 ORISE 5272S0033 5949710 2160611 5,400 5,600 a This sample is likely a characterization sample based on the naming convention.

Humboldt Bay Power Plant Confirmatory Survey Report B-1 5272-SR-04-0

Table B.2. ORISE Random Soil Sample Results (pCi/g) 5272S0024 5272S0025 5272S0026 5272S0028 ROC Conc. TPUa MDCb Conc. TPU MDC Conc. TPU MDC Conc. TPU MDC Am-241 -0.020 +/- 0.029 0.088 -0.004 +/- 0.054 0.132 -0.031 +/- 0.022 0.069 -0.10 +/- 0.44 1.08 Cm-245 -0.039 +/- 0.095 0.221 -0.011 +/- 0.086 0.200 -0.047 +/- 0.079 0.179 0.7 +/- 1.6 3.8 Co-60 0.009 +/- 0.020 0.048 -0.014 +/- 0.015 0.027 0.013 +/- 0.020 0.048 -0.09 +/- 0.21 0.54 Cs-137 0.033c +/- 0.015 0.029 0.019 +/- 0.009 0.017 0.010 +/- 0.012 0.028 0.33 +/- 0.17 0.36 Eu-152 0.011 +/- 0.047 0.109 0.005 +/- 0.029 0.069 -0.005 +/- 0.040 0.089 -0.12 +/- 0.61 1.43 Eu-154 -0.142 +/- 0.092 0.196 -0.130 +/- 0.064 0.106 -0.012 +/- 0.059 0.174 0.2 +/- 1.0 2.3 Nb-94 0.005 +/- 0.018 0.041 0.001 +/- 0.008 0.026 0.003 +/- 0.015 0.033 -0.06 +/- 0.23 0.49 Np-237 by Pa-233 0.012 +/- 0.029 0.067 -0.003 +/- 0.020 0.047 0.001 +/- 0.026 0.058 -0.23 +/- 0.42 0.95 SOF 0.019 0.003 0.006 0.104 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

Table B.3. ORISE Random Soil Sample Results (pCi/g) 5272S0029 5272S0030 5272S0031 5272S0032 ROC Conc. TPUa MDCb Conc. TPU MDC Conc. TPU MDC Conc. TPU MDC Am-241 -0.024 +/- 0.027 0.063 -0.046 +/- 0.061 0.144 -0.026 +/- 0.029 0.069 -0.084 +/- 0.068 0.156 Cm-245 0.017 +/- 0.079 0.189 -0.035 +/- 0.092 0.213 0.024 +/- 0.079 0.189 -0.06 +/- 0.27 0.63 Co-60 0.003 +/- 0.016 0.037 0.001 +/- 0.016 0.033 0.022 +/- 0.016 0.043 0.040 +/- 0.069 0.165 Cs-137 0.011 +/- 0.015 0.034 0.016 +/- 0.010 0.022 0.016 +/- 0.009 0.027 0.429c +/- 0.077 0.096 Eu-152 0.009 +/- 0.038 0.089 -0.013 +/- 0.032 0.074 -0.013 +/- 0.036 0.079 0.14 +/- 0.15 0.36 Eu-154 -0.029 +/- 0.070 0.179 -0.049 +/- 0.058 0.134 -0.079 +/- 0.077 0.155 -0.38 +/- 0.34 0.65 Nb-94 -0.002 +/- 0.015 0.032 -0.002 +/- 0.013 0.028 -0.005 +/- 0.013 0.028 0.001 +/- 0.066 0.146 Np-237 by Pa-233 -0.014 +/- 0.016 0.059 0.002 +/- 0.023 0.054 -0.004 +/- 0.024 0.054 -0.02 +/- 0.10 0.23 SOF 0.004 0.004 0.009 0.079 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

Humboldt Bay Power Plant Confirmatory Survey Report B-2 5272-SR-04-0

Table B.4. Archived FSS Soil Sample Results (pCi/g)

FSS-2377: OOL10-20-005-F 2012-003: HBPP-CHAR-OOL10-05-C FSS-2154: OOL10-25-003-F-RC FSS-1857: OOL10-25-007-F ROC Conc. TPUa MDCb Conc. TPU MDC Conc. TPU MDC Conc. TPU MDC Am-241 -0.045 +/- 0.063 0.153 -0.016 +/- 0.032 0.077 -0.083 +/- 0.037 0.083 0.021 +/- 0.019 0.075 Cm-245 0.008 +/- 0.095 0.222 0.032 +/- 0.087 0.209 -0.020 +/- 0.098 0.227 -0.082 +/- 0.095 0.215 Co-60 -0.004 +/- 0.016 0.032 -0.006 +/- 0.049 0.102 -0.022 +/- 0.028 0.050 0.006 +/- 0.019 0.045 Cs-137 -0.013 +/- 0.013 0.027 0.058c +/- 0.020 0.035 0.015 +/- 0.020 0.046 0.004 +/- 0.018 0.047 Eu-152 -0.034 +/- 0.036 0.079 0.029 +/- 0.059 0.140 -0.037 +/- 0.048 0.102 -0.001 +/- 0.048 0.109 Eu-154 -0.104 +/- 0.065 0.141 -0.29 +/- 0.18 0.31 -0.085 +/- 0.090 0.202 -0.113 +/- 0.069 0.181 Nb-94 0.015 +/- 0.013 0.031 0.006 +/- 0.017 0.040 -0.001 +/- 0.017 0.040 -0.005 +/- 0.016 0.035 Np-237 by Pa-233 0.013 +/- 0.022 0.054 -0.006 +/- 0.028 0.062 -0.003 +/- 0.032 0.072 0.004 +/- 0.030 0.068 SOF 0.014 0.013 0.002 0.007 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

Table B.5. Archived FSS Soil Sample Results (pCi/g)

FSS-0694: NOL01-03-01-106-F-RC FSS-0519: OOL01-03-011-F-RC FSS-1707: OOL09-02-004-F FSS-2190: OOL07-03-120-F ROC Conc. TPUa MDCb Conc. TPU MDC Conc. TPU MDC Conc. TPU MDC Am-241 -0.035 +/- 0.034 0.081 -0.024 +/- 0.063 0.155 -0.029 +/- 0.026 0.082 -0.063 +/- 0.029 0.085 Cm-245 0.015 +/- 0.090 0.215 0.042 +/- 0.098 0.233 -0.007 +/- 0.070 0.219 0.054 +/- 0.095 0.228 Co-60 0.004 +/- 0.028 0.061 0.010 +/- 0.026 0.057 0.012 +/- 0.014 0.059 -0.003 +/- 0.015 0.044 Cs-137 0.018 +/- 0.015 0.033 0.026c +/- 0.012 0.024 0.025 +/- 0.014 0.027 -0.009 +/- 0.023 0.046 Eu-152 -0.021 +/- 0.053 0.116 -0.010 +/- 0.040 0.094 -0.050 +/- 0.046 0.096 -0.022 +/- 0.050 0.109 Eu-154 -0.048 +/- 0.095 0.226 -0.195 +/- 0.097 0.160 -0.14 +/- 0.11 0.22 -0.19 +/- 0.11 0.20 Nb-94 0.002 +/- 0.018 0.040 -0.003 +/- 0.014 0.030 -0.003 +/- 0.015 0.033 0.008 +/- 0.017 0.040 Np-237 by Pa-233 -0.007 +/- 0.030 0.066 0.007 +/- 0.023 0.055 0.005 +/- 0.029 0.066 -0.000d +/- 0.030 0.068 SOF 0.004 0.015 0.011 0.004 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

d Zero due to rounding Humboldt Bay Power Plant Confirmatory Survey Report B-3 5272-SR-04-0

Table B.6. Archived FSS Soil Sample Results (pCi/g)

FSS-2057: OOL09-07-020-F FSS-1589: OOL09-06-003-F-RC ROC Conc. TPUa MDCb Conc. TPU MDC Am-241 0.013 0.052 0.126 -0.08 0.12 0.28 Cm-245 0.06 0.11 0.26 0.11 0.15 0.36 Co-60 -0.013 0.018 0.034 0.004 0.027 0.058 Cs-137 0.001 0.009 0.040 -0.002 0.021 0.048 Eu-152 -0.030 0.037 0.084 0.014 0.055 0.132 Eu-154 -0.078 0.079 0.174 -0.36 0.14 0.23 Nb-94 0.007 0.015 0.034 0.007 0.022 0.049 Np-237 by Pa-233 -0.008 0.025 0.059 -0.005 0.036 0.085 SOF 0.005 0.010 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

Humboldt Bay Power Plant Confirmatory Survey Report B-4 5272-SR-04-0

Table B.7. ORISE Judgmental Soil Sample Results (pCi/g) 5272S0027 5272S0033 ROC Conc. TPUa MDCb Conc. TPU MDC Am-241 -0.023 0.097 0.239 0.050 0.094 0.236 Cm-245 -0.00d 0.14 0.32 0.06 0.13 0.30 Co-60 0.016 0.021 0.052 -0.027 0.023 0.037 Cs-137 0.077c 0.019 0.028 0.132 0.023 0.028 Eu-152 0.035 0.047 0.119 -0.010 0.045 0.107 Eu-154 0.001 0.081 0.202 -0.146 0.094 0.172 Nb-94 0.013 0.018 0.044 0.009 0.018 0.041 Np-237 by Pa-233 0.042 0.025 0.053 0.036 0.031 0.078 SOF 0.058 0.056 a Uncertainties are based on total propagated uncertainties at the 95% confidence level.

b MDC = minimum detectable concentration.

c Results greater than the analytical MDC are bolded.

d Zero due to rounding.

Humboldt Bay Power Plant Confirmatory Survey Report B-5 5272-SR-04-0

Table B.8. WMF Sample Locations and Direct Measurements Total Activity Removable Activity Sample ID Location Alpha Beta Alpha Beta H-3 C-14 dpm/100 cm2 dpm/100 cm2 dpm/100 cm2 5272R0001 Behind South Push Wall, Western Wall 30 1,300 0 2 -- --

5272R0002 Behind South Push Wall, Western Floor 50 1,600 0 0 -2 -4 5272R0003 Behind South Push Wall, Middle Floor 10 1,800 0 2 -- --

5272R0004 Behind South Push Wall, Middle Wall 10 1,200 0 2 -- --

5272R0005 Behind South Push Wall, Eastern Wall 20 1,300 0 2 -- --

5272R0006 Behind South Push Wall, Eastern Floor 20 1,600 0 3 -- --

5272R0007 Behind North Push Wall, Middle Floor 40 1,600 0 0 -7 1 5272R0008 Behind North Push Wall, Middle Wall 20 1,200 0 0 -- --

5272R0009 Behind North Push Wall, Eastern Wall 20 1,400 0 0 -- --

Minimum 10 1,200 0 0 -7 -4 Maximum 50 1,800 0 3 -2 1 Humboldt Bay Power Plant Confirmatory Survey Report B-6 5272-SR-04-0

APPENDIX C: MAJOR INSTRUMENTATION Humboldt Bay Power Plant Confirmatory Survey Report 5272-SR-04-0

C.1. SCANNING AND MEASUREMENT INSTRUMENT/

DETECTOR COMBINATIONS 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.1.1 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 Geo 7X (Trimble Navigation Limited, Sunnyvale, CA)

C.1.2 ALPHA-PLUS-BETA Ludlum Gas-flow Proportional Detector Model 43-68, 126 cm2 physical area, 0.8 mg/cm2 Mylar window (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas)

Ludlum Gas-flow Proportional Detector Model 43-37, 584 cm2 physical area, 0.8 mg/cm2 Mylar window (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas)

C.1.3 ALPHA Ludlum Gas-flow Proportional Detector Model 43-68, 126 cm2 physical area, 0.8 mg/cm2 Mylar window (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas)

C.1.4 BETA Ludlum Gas-flow Proportional Detector Model 43-68, 126 cm2 physical area, 3.8 mg/cm2 Mylar window (Ludlum Measurements, Inc., Sweetwater, Texas) coupled to: Ludlum Ratemeter-scaler Model 2221 (Ludlum Measurements, Inc., Sweetwater, Texas)

Humboldt Bay Power Plant Confirmatory Survey Report C-1 5272-SR-04-0

C.2. LABORATORY ANALYTICAL INSTRUMENTATION Low-Background Gas Proportional Counter Series 5 XLB (Canberra, Meriden, Connecticut)

Used in conjunction with:

Eclipse Software Dell Workstation (Canberra, Meriden, Connecticut)

High-Purity, Extended Range Intrinsic Detector CANBERRA/Tennelec Model No: ERVDS30-25195 Canberra Lynx Multichannel Analyzer Canberra Gamma-Apex Software (Canberra, Meriden, Connecticut)

Used in conjunction with:

Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, Tennessee) and Dell Workstation (Canberra, Meriden, Connecticut)

High-Purity, Intrinsic Detector EG&G ORTEC Model No. GMX-45200-5 Canberra Lynx Multichannel Analyzer Canberra Gamma-Apex Software (Canberra, Meriden, Connecticut)

Used in conjunction with:

Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, Tennessee) and Dell Workstation (Canberra, Meriden, Connecticut)

High-Purity, Intrinsic Detector EG&G ORTEC Model No. GMX-30P4 Canberra Lynx Multichannel Analyzer Canberra Gamma-Apex Software (Canberra, Meriden, Connecticut)

Used in conjunction with:

Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, Tennessee) and Dell Workstation (Canberra, Meriden, Connecticut)

Humboldt Bay Power Plant Confirmatory Survey Report C-2 5272-SR-04-0

High-Purity, Intrinsic Detector EG&G ORTEC Model No. CDG-SV-76/GEM-MX5970-S Canberra Lynx Multichannel Analyzer Canberra Gamma-Apex Software (Canberra, Meriden, Connecticut)

Used in conjunction with:

Lead Shield Model G-11 (Nuclear Lead, Oak Ridge, Tennessee) and Dell Workstation (Canberra, Meriden, Connecticut)

Liquid Scintillation Counter Perkin Elmer Tricarb 5110TR (Perkin Elmer, Waltham, Massachusetts)

Humboldt Bay Power Plant Confirmatory Survey Report C-3 5272-SR-04-0

APPENDIX D: SURVEY AND ANALYTICAL PROCEDURES Humboldt Bay Power Plant Confirmatory Survey Report 5272-SR-04-0

D.1. PROJECT HEALTH AND SAFETY ORISE performed all survey activities in accordance with the ORAU Radiation Protection Manual, the ORAU Radiological and Environmental Survey Procedures Manual, and the ORAU Health and Safety Manual, (ORAU 2014, ORAU 2016a, and ORAU 2016b). 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 walk down of the survey areas were completed with field personnel to identify hazards present and discuss safety concerns. Should ORISE have identified a hazard not covered in the ORAU Radiological and Environmental Survey Procedures Manual (ORAU 2016a) or the projects Work-Specific Hazard Checklist for the planned survey and sampling procedures, work would not have been initiated or continued until the hazard was addressed by an appropriate job hazard analysis and hazard controls.

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

Field survey activities were conducted in accordance with procedures from the following documents:

  • ORAU Radiological and Environmental Survey Procedures Manual (ORAU 2016a)
  • ORAU Environmental Services and Radiation Training Quality Program Manual (ORAU 2019a)
  • ORAU Radiological and Environmental Analytical Laboratory Procedures Manual (ORAU 2019b)

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

Humboldt Bay Power Plant Confirmatory Survey Report D-1 5272-SR-04-0

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 and Intercomparison Testing Program laboratory quality assurance programs
  • Training and certification of all individuals performing procedures
  • Periodic internal and external audits D.3. SURVEY PROCEDURES D.3.1 SURFACE SCANS Gamma scans were performed using a hand-held thallium-doped sodium iodide (NaI[Tl])

scintillation detector with a 5 cm by 5 cm crystal. Alpha-plus-beta scans were performed using either the large-area (floor monitor) or hand-held gas proportional detector with a 0.8 (milligram per square centimeter (mg/cm2) window with a physical detector area of 584 cm2 or 126 cm2, respectively. Scans for elevated radiation were performed by passing the detector slowly over the surface. The distance between the detector and surface was maintained at a minimum. The NaI[Tl]

and floor monitor detectors were used solely as a qualitative means to identify elevated 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 and quantitatively investigated using other hand-held instruments.

Surface scan minimum detectable concentrations (MDCs) for the hand-held gas proportional detectors were estimated using the approach described in NUREG-1507 (NRC 1998). The scan MDC is a function of many variables, including a two-second observation interval, a specific level of performance at the first scanning state of 95% true positive and 25% false positive rate, which yields a d' value of 2.32 (NUREG-1507, Table 6.1), and a surveyor efficiency of 0.5. The total efficiency for beta was 0.14 based on Cs-137. Per the PG&E Final Status Survey Planning Worksheet for the survey units in the Waste Management Facility building, Cs-137 was the only positive result for Humboldt Bay Power Plant Confirmatory Survey Report D-2 5272-SR-04-0

plant-derived radionuclides identified during the characterization survey (PG&E 2019). The scan MDC was calculated using the following equation:

x x 60 x (60/)

=

x x 100 2 Where:

d' = index of sensitivity Cb = background (cpm) i = observation interval (sec) p = surveyor efficiency t = total efficiency The scan MDC for a nominal instrument background of 200 cpm was 1,500 dpm/100 cm2 for the hand-held gas proportional detectors.

D.3.2 SURFACE ACTIVITY MEASUREMENTS Measurements of gross alpha and beta surface activity levels were performed using hand-held gas proportional detectors coupled to portable ratemeter-scalers. Count rates, which were a one-minute count with the detector held in a static position, were converted to activity levels by dividing the count rate by the total static efficiency and correcting for the physical area of the detector. For conservatism the licensee elected not to subtract out background. The MDC for static survey activity measurements was calculated using the following equation:

3 + (4.65)

=

x x Where:

B = background in time interval, T (1 min)

T = count time (min) used for field instruments

= total efficiency = x (instrument efficiency x source efficiency)

G = geometry correction factor (1.26)

Humboldt Bay Power Plant Confirmatory Survey Report D-3 5272-SR-04-0

The static MDC was 390 dpm/100 cm2 for beta, based on a nominal instrument background of 200 cpm and 90 dpm/100 cm2 alpha, with a nominal instrument background of 2 cpm (using an efficiency of 0.08 for Th-230).

D.3.3. REMOVABLE ACTIVITY SAMPLING Smear sampling for removable gross alpha and gross beta contamination as well as for hard-to-detect (HTD) radionuclides were obtained from independent confirmatory measurement locations.

Removable activity samples were collected using numbered filter paper disks. Moderate pressure was applied to the smear and approximately 100 cm2 of the surface was wiped. Smears for gross alpha and beta analysis were placed in labeled envelopes. Smears for HTD analysis were first wetted with deionized water before the surface was wiped. Wet smears were placed in glass vials with deionized water. Locations and other pertinent data were recorded and all samples were transferred under chain-of-custody.

D. 3.4. SOIL SAMPLING Soil samples (approximately 0.5 kilogram each) were collected by ORISE personnel using a clean garden trowel to transfer soil into a new sample container. The container was then labeled and security sealed in accordance with ORISE procedures. ORISE shipped samples under chain-of-custody to the ORISE laboratory for analysis.

D.4. RADIOLOGICAL ANALYSIS D.4.1 GROSS ALPHA/BETA Dry smears were counted on a low-background proportional counter for gross alpha and beta activity. The minimum detectable activity of the procedures is approximately 11 dpm/100 cm2 for alpha and 14 dpm/100 cm2 for beta.

D. 4.2. GAMMA SPECTROSCOPY Samples were analyzed as received, and homogenized as necessary, and a portion sealed into an appropriate sized - 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 Humboldt Bay Power Plant Confirmatory Survey Report D-4 5272-SR-04-0

and Compton stripping, peak search, peak identification, and concentration calculations were performed using 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.

Table D.1. Typical MDCs Total Absorption Peak Radionuclide TAP (MeV)a MDC (pCi/g)

Co-60 1.332 0.06 Cs-137 0.662 0.05 Eu-152 0.344 0.10 Eu-154 0.723 0.15 D.4.3 H-3 AND C-14 ANALYSIS Smear samples were placed into a scintillation cocktail without sample preparation and counted in a liquid scintillation analyzer. Tritium (H-3) and carbon-14 (C-14) values were calculated using the known efficiency in the appropriate energy region.

D.4.4 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 Power Plant Confirmatory Survey Report D-5 5272-SR-04-0

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