HBL-21-008, Annual Radiological Environmental Monitoring Report for 2020

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Annual Radiological Environmental Monitoring Report for 2020
ML21119A130
Person / Time
Site: Humboldt Bay
Issue date: 04/28/2021
From: Nelson E
Pacific Gas & Electric Co
To:
Document Control Desk, Office of Nuclear Material Safety and Safeguards, NRC/OCM
References
PG&E Letter HBL-21-008
Download: ML21119A130 (29)
v • d • e


Text

m Pacific Gas and Electric Company*

Eric P. Nelson Director Nuclear Decommissioning Diablo Canyon Power Plant Mail Code: 252-2-NW San Luis Obispo, CA 93424 805-545-4777 Internal: 691-4777 E-Mail: epn1@pge.com April 28, 2021 PG&E Letter HBL-21-008 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-133, DPR-7 Humboldt Bay Power Plant Unit 3 Annual Radiological Environmental Monitoring Report for 2020

Dear Commissioners and Staff:

In accordance with Section 4.1 of the SAFSTOR/Decommissioning Offsite Dose Calculation Manual (ODCM), Pacific Gas and Electric Company hereby submits the 2020 Annual Radiological Environmental Monitoring Report (REMP). The REMP, provided in the enclosure covers the reporting period from January 1 through December 31, 2020. The report contains material consistent with the objectives outlined in the ODCM, and in 10 CFR Part 50, Appendix I, Sections IV.B.2, IV.B.3, and IV.C.

There are no new or revised regulatory commitments (as defined in NEI 99-04) in this submittal.

If you have any questions regarding information in the enclosed report, please contact Mr. Philippe Soenen at (805) 459-3701.

Sincerely, L P~

Eric P. Nelson Enclosure cc: HBPP Distribution cc/enc: Scott A. Morris, NRC Region IV Administrator Amy M. Snyder, NRC Project Manager

Enclosure PG&E Letter HBL-21-008 HUMBOLDT BAY POWER PLANT UNIT 3 ANNUAL RADIOLOGICAL ENVIRONMENTAL MONITORING REPORT JANUARY 1 THROUGH DECEMBER 31, 2020

TABLE OF CONTENTS A. RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM ............................ 1

1. Program Description ............................................................................................ 1
2. Monitoring Requirements ..................................................................................... 2
a. Offsite Environmental Monitoring ................................................................... 2
b. Onsite Environmental Monitoring ................................................................... 3
c. Other Monitoring ............................................................................................. 4
3. Interlaboratory Comparison Program ................................................................... 4
4. NEI Groundwater Protection Initiative .................................................................. 5 B. TRENDS, BASELINE COMPARISONS AND INTERPRETATIONS ......................... 5
1. General Comments.............................................................................................. 5
2. Direct Radiation Pathway .................................................................................... 5
3. Airborne Pathway ................................................................................................ 6
4. Waterborne Pathway ........................................................................................... 6
a. Surface Water ................................................................................................ 6
b. Groundwater................................................................................................... 6
5. Ingestion Pathway ............................................................................................... 7
6. Terrestrial Pathway .............................................................................................. 7 C. MONITORING RESULTS ......................................................................................... 8
1. Annual Summary ................................................................................................. 8
2. Direct Radiation Pathway .................................................................................... 8
3. Airborne Pathway ................................................................................................ 8
4. Waterborne Pathway ........................................................................................... 9
a. Surface Water ................................................................................................ 9

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TABLE OF CONTENTS (Continued)

b. Groundwater................................................................................ .9
5. Ingestion Pathway ............................................................................................... 9
6. Terrestrial Pathway ............................................................................................. .9
7. NEI Groundwater Protection Initiative Voluntary Reporting Results.......9
8. Errata For Previous Years Reports ...................................10

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LIST OF TABLES Table Page A-1 HBPP RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM ............ 11 A-2 DISTANCES AND DIRECTIONS TO HBPP OFFSITE SAMPLE LOCATIONS ... 11 A-3 GEL PARTICIPATION - INTERLABORATORY CROSS-CHECK PROGRAM.

DATA..12 C-1 RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM ANNUAL REPORT

SUMMARY

........................................................................................... 13 C-2 ONSITE ENVIRONMENTAL TLD STATIONS ...................................................... 14 C-3 OFFSITE (Control) ENVIRONMENTAL TLD STATIONS ..................................... 16 C-4 ODCM REQUIRED AIR SAMPLES ...................................................................... 17 LIST OF FIGURES Figure Page A-1 HBPP ONSITE AIR SAMPLE LOCATIONS ......................................................... 18 A-2 HBPP ONSITE TLD LOCATIONS ........................................................................ 19 A-3 HBPP OFFSITE TLD LOCATIONS ...................................................................... 20 B-1 OFFSITE ENVIRONMENTAL RADIATION LEVEL TRENDS .............................. 23 B-2 ONSITE ENVIRONMENTAL RADIATION LEVEL TRENDS ................................ 24

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PACIFIC GAS AND ELECTRIC COMPANY ANNUAL RADIOLOGICAL ENVIRONMENTAL MONITORING REPORT FOR HUMBOLDT BAY POWER PLANT UNIT 3, COVERING THE PERIOD JANUARY 1 THROUGH DECEMBER 31, 2020 This annual report is required by Section 4.1 of the SAFSTOR/Decommissioning Offsite Dose Calculation Manual (ODCM). This report provides information about the Radiological Environmental Monitoring Program (REMP) for the period of January 1 through December 31, 2020, in a manner consistent with the objectives outlined in the ODCM, and in 10 CFR Part 50, Appendix I, Sections IV.B.2, IV.B.3, and IV.C.

The report has three sections. Section A provides a summary description of the REMP, including maps of sampling locations. Section A also provides the results of offsite contract laboratory participation in the Interlaboratory Comparison Program.

Section B provides summaries, interpretations, and analyses of trends of the results of the REMP for the reporting period. The material provided is consistent with the objectives outlined in the ODCM, and in 10 Part CFR 50, Appendix I, Sections IV.B.2, IV.B.3, and IV.C. Section B also includes a comparison with the baseline environmental conditions at the beginning of SAFSTOR.

Section C provides the results and analyses of radiological environmental samples and of environmental radiation measurements taken during the period pursuant to the quality related locations specified in the table and figures in the ODCM. These results are presented as both summarized and tabulated results of these analyses and measurements. The summarized results are formatted for applicable reporting requirements of the NRC Radiological Assessment Branchs Branch Technical Position.

A. RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM

1. Program Description The NRC Radiological Assessment Branch issued a Branch Technical Position (BTP) on environmental monitoring in March 1978. Revision 1 of the BTP was issued as Generic Letter 79-65, Radiological Environmental Monitoring Program Requirements - Enclosing Branch Technical Position, Revision 1, dated November 27, 1979, and sets forth an example of an acceptable minimum radiological monitoring program. The specified environmental monitoring program provides measurements of radiation and of radioactive materials in those exposure pathways and for those radionuclides that lead to the highest potential radiation exposures of individuals resulting from plant effluents.

As discussed below, many of the exposure pathway sample requirements specified in the BTP are not required for the Humboldt Bay Power Plant (HBPP)

REMP because of the baseline conditions established in the SAFSTOR Decommissioning Plan (now identified as the Post Shutdown Decommissioning Activities Report (PSDAR), Defueled Safety Analysis Report (DSAR)) and the Environmental Report.

In addition, the nuclides specified for analysis by the BTP have been revised to reflect the available source term at a nuclear power plant that has been shut down since July 2, 1976.

The REMP consists of the collection and analysis of both onsite and offsite environmental samples. HBPP personnel perform sample collection and sample analysis of airborne radioactivity. General Engineering Laboratories (GEL) personnel no longer perform effluent sample analyses as ground water radioactivity monitoring was discontinued in 2017. ODCM Revision 32, effective in February 2020, removed all remaining onsite and offsite environmental sample locations, final TLDs were removed at normal quarter end interval on April 1, 2020. Mirion Technologies personnel perform analysis of thermoluminiscent dosimeters (TLDs) used for monitoring direct radiation. A summary of the REMP is provided as Table A-1, HBPP RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM.

Sample collection for the REMP is performed at the sampling stations defined by Table A-2, DISTANCES AND DIRECTIONS TO HBPP OFFSITE SAMPLE LOCATIONS, Figure A-1, HBPP ONSITE AIR SAMPLE LOCATIONS; Figure A-2, HBPP ONSITE TLD LOCATIONS, and Figure A-3 HBPP OFFSITE TLD LOCATIONS.

2. Monitoring Requirements
a. Offsite Environmental Monitoring
1. Airborne The ODCM required zero (0) offsite environmental air sampling stations.

ODCM revision 31, effective Q4 of 2019, removed all remaining offsite air sampling locations.

2. Direct Radiation The ODCM required four (4) offsite environmental monitoring stations and one (1) offsite control station equipped with TLDs to monitor gamma exposure. The TLDs are required to be exchanged quarterly. Offsite environmental stations selected to satisfy this requirement are Stations 1, 2, 14, 25, while T17 is the offsite control station as shown on Figure A-3.

These stations are considered to represent the offsite locations for the direct radiation pathway. ODCM R evision 32, effective February 2020, eliminated onsite and offsite TLD locations, however, final TLDs were removed at normal quarter end interval on April 1, 2020.

3. Ingestion The requirement to perform milk sampling was removed from the ODCM in Revision 24 based upon no detection of Sr-90 or plant-related gamma emitters in milk since decommissioning began.
b. Onsite Environmental Monitoring
1. Airborne The ODCM required two (2) onsite air sampling stations. The stations selected to satisfy this requirement are Stations AM2 and AM4 as shown on Figure A-1. The two air sampling locations generally represent two major compass sectors (N, S) and areas that are potentially approachable by a member of the public. The air samplers are run continuously, and samples are analyzed weekly for Gross Beta and Gross Alpha activity.

Quarterly composited samples were not analyzed by station to facilitate demobilization of the onsite count lab. The number of onsite air sampling stations was reduced from two (2) to zero (0) during 2020 with ODCM Revision 32, effective February 2020, removed all remaining onsite air sampling locations.

2. Direct Radiation The ODCM required a minimum of 8 onsite environmental monitoring stations at or within the site boundary fence line, equipped with TLDs to monitor gamma exposure. TLDs are required to be exchanged quarterly.

A total of 16 TLD stations were used to satisfy this requirement. Stations T1 through T16 are shown on Figure A-2.

Each quarter the exposures from 16 stations are determined, which normally results in 64 analyses for a full year, however, this was reduced to one quarter of data collection in 2020. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations, however, final TLDs were removed at normal quarter end interval on April 1, 2020. Each TLD station had three TLDs, each containing a number of phosphors (normally three). The phosphor exposures for each TLD are averaged and then the three TLDs per station are averaged to provide the quarterly exposure for the station.

3. Waterborne Surface Water Effective December 31, 2013, discharge of processed radioactive liquid effluents to Humboldt Bay was terminated. Any remaining or incidental radioactive liquids in concentrations exceeding 10 times 10 CFR 20, Appendix B, Table 2 Column 2 are manifested for disposal at a regulated disposal facility. Sampling of surface water is not required by the current revision of the ODCM.

Groundwater Revision 23 of the ODCM transferred ground water monitoring program requirements from the ODCM to HBPPs ground water monitoring program procedures. This was done to allow operational flexibility needed to adjust to changes to site access and hydrogeology as soils and building substructures are removed. After May 2017, formal closure of the ground water monitoring program was initiated. There were no well locations sampled in 2020.

c. Other Monitoring Offsite airborne, ingestion and terrestrial pathway monitoring is not required by the ODCM. The Environmental Report, submitted to the NRC as Attachment 6 to SAFSTOR License Amendment Request 84-01, dated July 31, 1984, established baseline conditions for these pathways. In accordance with the NRC-approved SAFSTOR Decommissioning Plan, (now identified as the PSDAR and DSAR), these baseline conditions will only need to be reestablished prior to final decommissioning if a significant release occurs during SAFSTOR. The Environmental Report also contains a description of the demography and human activities within the environs surrounding the site.
3. Interlaboratory Comparison Program PG&Es contract laboratory, GEL, has analyzed evaluation samples provided by a commercial supplier to satisfy the requirement to participate in an Interlaboratory Cross-Check Program. Results are provided in Table A-3, GEL PARTICIPATION - INTERLABORATORY CROSS-CHECK PROGRAM DATA.

With the termination of the ground water monitoring program in 2017, GEL no longer provides analyses of REMP samples for HBPP.

GELs Third-Party Cross-Check Program provides environmental matrices representative of past HBPP analyses and is intended to meet or exceed the interlaboratory comparison program requirements of NRC Regulatory Guide 4.15. GEL analyzed one (1) Eckert & Ziegler individual environmental sample analyses in Q1 of 2020. All results met GELs acceptance criteria (100 percent within acceptance).

With the demobilization of HBPP onsite count room, which commenced in Q4 of 2019, HBPP did not participate in the Eckert & Ziegler Interlaboratory Cross-Check Program in 2020.

4. NEI Groundwater Protection Initiative Based on the state of decommissioning at HBPP, there remains little potential for ground water to become contaminated during the final stages of decommissioning. No groundwater monitoring was performed in 2020. Formal closure of the ground water monitoring wells was initiated in 2017 and concluded in 2019. Ground water monitoring wells were closed in accordance with local water authority guidance and permits under Work Package 99-28, Well Abandonment. Sampling of ground water monitoring wells was discontinued after the second quarter of 2017.

B. TRENDS, BASELINE COMPARISONS AND INTERPRETATIONS Section B provides interpretations of results, and analyses of trends of the results. The material provided is consistent with the objectives outlined in the ODCM, and in 10 CFR Part 50, Appendix I, Sections IV.B.2, IV.B.3, and IV.C.

Section B also includes a comparison with the baseline environmental conditions at the beginning of SAFSTOR.

1. General Comments The Environmental Report, submitted to the NRC as Attachment 6 to SAFSTOR License Amendment Request 84-01, established baseline conditions for soil, biota and sediments. The results to date indicate no change from the baseline environmental conditions established in the Environmental Report.

The results, interpretations, and analysis of trends of the results, indicate that SAFSTOR activities have had no measurable radiological effect on the environment. Facility surveys for radiation and radioactive surface contamination are performed on both a scheduled basis and on an as-required basis. PG&E has completed all Decommissioning Demolition Activities of Unit 3 end of 2019, as a result, performance of all radiological surveys was suspended for the monitoring period of 2020.

As discussed below, the ODCM calculation model conservatively assumes that exposure pathways begin at the unrestricted area boundary, also known as the owner-controlled area (OCA) boundary. Since there have been no changes in the location of the unrestricted area boundary, no survey for changes to the use of unrestricted areas was necessary.

2. Direct Radiation Pathway A plot of the radiation level trends for the five (offsite) locations is shown in Figure B-1, OFFSITE ENVIRONMENTAL RADIATION LEVEL TRENDS. A plot of the radiation level trends for onsite stations is shown in Figure B-2, ONSITE ENVIRONMENTAL RADIATION LEVEL TRENDS. The plots show that the offsite annual doses continue to be within the ranges that have been observed over the last ten years.

HBPP changed TLD processing services beginning in January 2014. Data from previous years was based on a Panasonic TLD system. Data in 2014 to the present is based on Mirion Genesis type TLD system. The apparent rise in Figures B-1 and B-2 after 2014 may be a result of the change in monitoring devices and/or the increase in decommissioning activities.

Figure B-2 includes the average dose for two groups of onsite stations, selected by their potential to be affected by radioactive waste handling activities. Figure B-2 also shows that dose measurement variations can be attributed to in-plant sources and low-level waste packaging and shipping activities. However, allowing for the background change in the general environs, all measurements were comparable to the ranges observed at these locations since entering SAFSTOR, with the onsite station dose levels approximately within the range of dose levels shown by the offsite stations.

The ODCM calculation model for the direct radiation exposure pathway in past years assumed an occupancy factor for the portion of the unrestricted area boundary that was closest to the radioactive waste handling area of the plant.

ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations, however, final TLDs were removed at normal quarter end interval on April 1, 2020. The maximum first quarter dose, was seen on TLD T1, corrected to the 67-hour/yr occupancy, Teen Shoreline Recreation Pathway from Regulatory Guide 1.109, and subtracting the average of the five (5) offsite TLDs, the dose to the maximum exposed individual from this source was approximately 0.02 mrem above background.

The Humboldt Bay ISFSI is licensed under 10 CFR Part 72 but is contained within the licensed boundary of the HBPP site, so no other dose contributions to the public are considered. The HBPP site had no measurable liquid or gaseous radioactive effluents that would challenge the limitations of 40 CFR 190. The direct dose is the only contributor to public dose and is within the 25 millirem limit to the whole body.

3. Airborne Pathway Dose assessment based on offsite airborne pathway monitoring is not required by the ODCM. The Environmental Report, submitted to the NRC as Attachment 6 to SAFSTOR License Amendment Request 84-01, established baseline conditions for the airborne pathway. In accordance with the NRC-approved SAFSTOR Decommissioning Plan, (now identified as the PSDAR and DSAR), these baseline conditions will only need to be reestablished prior to final decommissioning if a significant release occurs during SAFSTOR. The ODCM calculation model for the airborne pathway assumes that the airborne exposure pathway (inhalation exposure) is at the unrestricted area boundary, which is the location of the highest potential exposure.
4. Waterborne Pathway
a. Surface Water Liquid radioactive wastes are shipped for disposal to a regulated disposal facility. Discharges of liquid radioactive effluent to Humboldt Bay were terminated in December 2013. Therefore, there were no discharges of liquid radioactive effluent to Humboldt Bay during the reporting period.
b. Groundwater Groundwater sampling of the waterborne pathway ceased in the second quarter of 2017. There were no spills challenging the groundwater in 2020.

The ODCM does not provide a model for the groundwater waterborne pathway, because the groundwater is saline and is not used now nor likely to be used in the future for either direct consumption or for agricultural purposes.

5. Ingestion Pathway Ingestion pathway monitoring is not required by the ODCM. The Environmental Report, submitted to the NRC as Attachment 6 to SAFSTOR License Amendment Request 84-01, established baseline conditions for the ingestion pathway. In accordance with the NRC-approved SAFSTOR Decommissioning Plan, (now identified as the PSDAR and DSAR), these baseline conditions will only need to be reestablished prior to final decommissioning if a significant release occurs during SAFSTOR.

The ODCM calculation model for the airborne pathway assumes that the ingestion pathways (milk, meat, and vegetable consumption) begin at the unrestricted area boundary, which is the location of the highest potential exposure, whether any dairy, farm, etc. is actually present.

6. Terrestrial Pathway Terrestrial pathway monitoring is not required by the ODCM. The Environmental Report, submitted to the NRC as Attachment 6 to SAFSTOR License Amendment Request 84-01, established baseline conditions for the terrestrial pathway. In accordance with the NRC-approved SAFSTOR Decommissioning Plan, (now identified as the PSDAR and DSAR), these baseline conditions will only need to be reestablished prior to final decommissioning if a significant release occurs during SAFSTOR.

The ODCM calculation model for the terrestrial pathway conservatively assumes that the terrestrial exposure (direct radiation from airborne radioactivity deposition) is at the unrestricted area boundary, which is the location of the highest potential exposure.

C. MONITORING RESULTS

1. Annual Summary Results of the REMP sampling and analysis are summarized in Table C-1 in the format of the BTP Table 3.

All the minimum detectable activities (MDAs) for analyses required by the REMP were less than or equal to the lower limit of detection (LLD) criteria for radioactivity in environmental samples specified in Table C-1 of this report.

Because alpha and beta radioactivity analyses of the saline ground water are less effective than tritium and gamma radioactivity analyses, the ODCM does not currently require alpha and beta radioactivity analyses in water to be part of the REMP. With demobilization of Ground Water Treatment System (GWTS) and demobilization of the HBPP count lab, both commencing in 2019, there was no need for, or onsite ability to, evaluate ground water/storm water radioactivity in 2020.

2. Direct Radiation Pathway Monitoring of the direct radiation pathway is performed at 16 onsite locations near the OCA fence line, and at four offsite environmental monitoring stations and one offsite (control) location (Location number T17) near the facility.

Monitoring is performed with TLDs with multiple crystal elements. Three TLDs are installed at each station, and the TLD sets are exchanged quarterly. The reported result and its standard error are calculated from the measurements of multiple elements in the TLD triplet. Results of the onsite and offsite monitoring are provided in Tables C-2 and C-3, respectively. All decommissioning demolition activities of Unit 3 were complete at the end of 2019. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.

3. Airborne Pathway Two onsite samples were collected and sent for offsite analysis for Gross Beta and Gross Alpha activity until ODCM Revision 32, effective February 2020, removed all air sample locations in the first quarter of 2020.

The required quarterly composited samples were analyzed for Gamma Isotopic by station. All air sample results for alpha and beta activity are provided in Table C-4. Onsite composite count capabilities ceased the fourth quarter of 2019 to facilitate demobilization of HBPP onsite count lab. The weekly samples were sent offsite to GEL and results for alpha and beta particulate met the effluent acceptance criteria in the ODCM. All LLDs were met for Gross Beta (required LLD 1.0E-02 pCi/m3).

4. Waterborne Pathway
a. Surface Water Surface water sampling of the waterborne pathway is no longer performed due to the termination of liquid effluent releases in December 2013.
b. Groundwater Groundwater sampling of the waterborne pathway ceased in the second quarter of 2017.
5. Ingestion Pathway Ingestion pathway monitoring is not required by the ODCM.
6. Terrestrial Pathway Terrestrial pathway monitoring is not required by the ODCM.
7. NEI Groundwater Protection Initiative Voluntary Reporting Results The NEI Groundwater Protection Initiative contains the following requirements:

OBJECTIVE 2.2 VOLUNTARY COMMUNICATION Make informal notification as soon as practicable to appropriate State/Local officials, with follow up notification to the NRC, as appropriate, regarding significant onsite leaks/spills into groundwater and onsite or offsite water sample results exceeding the criteria in the REMP as described in the ODCM/ODAM.

HBPP Response to 2.2:

There were no reports or notifications required to be generated in 2020 for groundwater results exceeding reporting/notification levels or significant onsite leaks/spills.

OBJECTIVE 2.3 THIRTY-DAY REPORTS Submit a 30-day report to the NRC for any water sample result for onsite groundwater that is or may be used as a source of drinking water that exceeds the criteria in the licensee's existing REMP for 30-day reporting of offsite water sample results. Copies of 30-day reports for both onsite and offsite water samples will also be provided to the appropriate State agency, and:

HBPP Response to 2.3:

There were no reports or notifications required to be generated in 2020 for groundwater results exceeding reporting/notification levels or significant onsite leaks/spills.

OBJECTIVE 2.4 ANNUAL REPORTING Document all on-site ground water sample results and a description of any significant on-site leaks/spills into groundwater for each calendar year in the AREOR for REMP or the ARERR for the RETS as contained in the appropriate reporting procedure, beginning with Calendar year 2006.

HBPP Response to 2.4:

Groundwater sampling of the waterborne pathway ceased in the second quarter of 2017.

There were no significant onsite leaks/spills into groundwater in 2020.

Note: the term "significant" is defined by the NEI Initiative as greater than 100 gallons.

8. No Errata for Previous Years Reports.

TABLE A-1 HBPP RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM Exposure Pathway Number of Samples Sampling and Collection Type of Analysis And/Or Sample And Locations (a) Frequency AIRBORNE Continuous sampler operation Gross alpha and 2 onsite locations with sample collection at least Gross beta once per 7 days radioactivity following filter change. Gamma Isotopic(b) analysis on quarterly composite (by station).

DIRECT RADIATION 8 onsite stations with TLDs TLDs exchanged quarterly Gamma exposure 5 offsite stations with TLDs TLDs exchanged quarterly Gamma exposure WATERBORNE Groundwater No longer required N/A N/A.

(a)

All decommissioning demolition activities of Unit 3 were complete end of 2019. The number of onsite and offsite sample / monitoring locations was scaled back to zero with implementation of ODCM Revision 32, effective February 2020, eliminated all airborne sample and TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.

(b)

Gamma isotopic analysis means the identification and quantification of gamma emitting radionuclides that may be attributable to the effluents from the facility. Onsite composite analysis were not performed in 2020 to facilitate demobilization of the onsite count lab.

TABLE A-2 DISTANCES AND DIRECTIONS TO HBPP OFFSITE SAMPLE LOCATIONS Radial Direction Offsite Radial Distance Station Measurement By From Plant Number Pathway Station Name Sector Degrees (Miles)

King Salmon 1 Direct Radiation Picnic Area W 270 0.3 2 Direct Radiation City of Fortuna SSE 158 9.4 Water Pollution Control Plant, 180 Dinsmore Drive, Fortuna 14 Direct Radiation South Bay School S 180 0.4 Parking Lot 25 Direct Radiation Irving Drive, SSE 175 1.3 Humboldt Hill T17 Direct Radiation Mitchell Heights NNE 61 5.8 Drive Note: All decommissioning demolition activities of Unit 3 were complete end of 2019. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.

TABLE A-3 GEL PARTICIPATION - INTERLABORATORY CROSS-CHECK PROGRAM DATA(1)

Sample/ Radionuclide Sample Quarter Report GEL Reference Ratio Evaluation Analysis Number 2020 Date Value Value (pCi/L) (pCi/L)

Gamma Water I-131 RAD-120 1st 2/24/20 3.18E+01 2.99E+01 1.06 Acceptable Ba-133 RAD-120 1st 2/24/20 5.92E+01 6.45E+01 0.92 Acceptable Cs-134 RAD-120 1st 2/24/20 2.15E+01 2.29E+01 0.94 Acceptable Cs-137 RAD-120 1st 2/24/20 2.17E+02 2.20E+02 0.99 Acceptable Co-60 RAD-120 1st 2/24/20 9.77E+01 9.12E+01 1.07 Acceptable Zn-65 RAD-120 1st 2/24/20 3.32E+02 2.98E+02 1.11 Acceptable LSC Water (2) Tritium RAD-120 1st 2/24/20 1.77E+04 1.78E+04 0.99 Acceptable GFP(3) Water Sr-90 RAD-120 1st 2/24/20 3.83E+01 3.65E+01 1.05 Acceptable Gross Alpha RAD-120 1st 2/24/20 6.71E+01 5.89E+01 1.14 Acceptable Gross Beta RAD-120 1st 2/24/20 2.00E+01 2.10E+01 0.95 Acceptable Note (1): In 2020 samples were sent to offsite lab for analysis. HBPP Lab was permanently closed fourth quarter of 2019 and did not participate in Eckert & Ziegler Interlaboratory Cross-Check Program in 2020.

Note (2): Liquid Scintillation Counter Note (3): Gas Flow Proportional TABLE C-1 RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM ANNUAL REPORT

SUMMARY

Name of Facility Humboldt Bay Power Plant Unit 3 Docket No. 50-133; License No. DPR-7 Location of Facility Humboldt County, California Reporting Period January 1 - December 31, 2020 (County, State)

Medium or Type and Lower Limit All Indicator Locations Location with Highest Control Number Pathway Total of Detection Annual Mean Locations of Non-Sampled Number of (LLD) a routine

[Unit of Analyses Reported Measurement] Performed Mean, (Fraction), & [Range]b Name Mean, Mean, Measure-(Fraction) (Fraction) ments

& [Range]b & [Range]b (6) samples per

  • Gross Beta Gross Alpha Offsite control N/A AIRBORNE station 1.00E-02 North (AM2) Relay (pCi/m3) mean sampler
  • Gross Beta, pCi/m3 Gross Alpha (pCi/m3) mean 2.54E-04, (1/6), [2.88E-05 to 7.18E-03] Bldg. 2.87E-04, (0/6), removed 2019.

Particulates

  • Gross Alpha Gross Beta (pCi/m3) mean 6.46E-03, (6/6), [4.17E-03 to 8.13E-03] (AM4) [1.26E-04 to
  • Gross Alpha Relay Building (AM4) 4.77E-04]

[pCi/m3] (2) Onsitec 1.00E1 Gross Alpha (pCi/m3) mean 2.87E-04, (0/6), [1.26E-04 to 4.77E-04]

Locations pCi/m3 Gross Beta (pCi/m3) mean 5.66E-03, (6/6), [4.37E-03 to 6.47E-03] North Gross Beta (0) Offsitec (AM2) (pCi/m3) mean Locations 6.46E-03, (6/6),

[4.17E-03 to 8.13E-03]

(16) Fence line 5 mRem Fence Line TLDs (T1 to T16) Station T- T1 (mR/qtr) Stations 1, 2, 0 DIRECT TLD readingsd 13.5 +/- 0.0, (16/16), [12.7 to 15.7] 1, mean 14, 25 and T17 RADIATION Figure B-1 15.7 +/- 2.1, (mR/qtr) mean (5) Off-site TLD (1/1), [15.7 to 13.3 +/- 0.1,

[mR/quarter] Readingsd 15.7] (5/5),

[12.0 to 15.0]

TABLE C-1 (CONTINUED)

RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM ANNUAL REPORT

SUMMARY

Type All Indicator Location with Highest Annual Mean Control Medium or and Total Lower Locations Locations Number of Pathway Sampled Number of Limit of Mean, Name, Mean, Mean, Non-routine

[Unit of Analyses Detection (Fraction) Distance and (Fraction) (Fraction) Reported Measurement] Performed (LLD) a & [Range] b Direction & [Range] b & [Range] b Measurements 0

WATERBORNE Groundwater Not Required N/A N/A N/A N/A Not Required Not Required Drinking Water Not Required N/A N/A N/A N/A Not Required N/A Sediment Not Required N/A N/A N/A N/A Not Required N/A Algae Not Required N/A N/A N/A N/A Not Required N/A INGESTION Not Required N/A N/A N/A N/A Not Required N/A TERRESTRIAL Soil Not Required N/A N/A N/A N/A Not Required N/A a

The LLD is defined as the smallest concentration of radioactive material in a sample that will yield a net count, above system background, that will be detected with 95 percent probability with only 5 percent probability of falsely concluding that a blank observation represents a real signal.

LLD is defined as the a priori (before the fact) lower limit of detection (as pCi per unit mass or volume) representing the capability of a measurement system and not as the a posteriori (after the fact) limit for a particular measurement. (Current literature defines the LLD as the detection capability for the instrumentation only, and the MDA, minimum detectable concentration, as the detection capability for a given instrument, procedure and type of sample.) The actual MDA values for the radionuclide specific analyses were at or below the LLD.

b The mean and the range are based on detectable measurements only. The fraction of detectable measurements at specified locations is indicated in parentheses; e.g., (1/6) means that 1 out of 6 samples contained detectable activity above the MDA, but below the LLD. The range of detected results is indicated in brackets; e.g., [23 to 34].

c The two onsite air samplers were reduced to zero with ODCM Revision 32, effective February 2020. All samples were sent to GEL for offsite analysis to facilitate HBPPs demobilized of the onsite count room.

d ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.

Not Required: Not required by the HBPP Unit 3 Technical Specifications or the SAFSTOR Offsite Dose Calculation Manual. Baseline environmental conditions for this parameter were established in the Environmental Report as referenced by the SAFSTOR Decommissioning Plan (now identified as the Post Shutdown Decommissioning Activities Report and Defueled Safety Analysis Report).

N/A - Not applicable TABLE C-2 ONSITE ENVIRONMENTAL TLD STATIONS Station TLD Exposure Measurements (mR)

Number First Quarter Second Quarter Third Quarter Fourth Quarter T1 15.7 +/- 2.1 Not Required Not Required Not Required T2 14.3 +/- 0.8 Not Required Not Required Not Required T3 12.7+/- 0.9 Not Required Not Required Not Required T4 14.0 +/- 0.5 Not Required Not Required Not Required T5 12.7 +/- 0.9 Not Required Not Required Not Required T6 13.0 +/- 0.5 Not Required Not Required Not Required T7 12.7 +/- 0.9 Not Required Not Required Not Required T8 14.3 +/- 0.8 Not Required Not Required Not Required T9 13.0 +/- 0.5 Not Required Not Required Not Required T10 13.0 +/- 0.5 Not Required Not Required Not Required T11 14.7 +/- 1.1 Not Required Not Required Not Required T12 13.0 +/- 0.5 Not Required Not Required Not Required T13 13.7 +/- 0.1 Not Required Not Required Not Required T14 13.3 +/- 0.2 Not Required Not Required Not Required T15 13.0 +/- 0.5 Not Required Not Required Not Required T16 13.3 +/- 0.2 Not Required Not Required Not Required Calculated Parameters (mR)

Parameter First Quarter Second Quarter Third Quarter Fourth Quarter Average 13.5 +/- 0.0 Not Required Not Required Not Required Maximum 15.7 +/- 2.1 Not Required Not Required Not Required Table C-2 Notes:

1. All decommissioning demolition activities of Unit 3 were complete end of 2019. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.
2. The reported exposures do not have an average background or transient dose subtracted.
3. Not Required: Not required by the HBPP Unit 3 Technical Specifications or the SAFSTOR Offsite Dose Calculation Manual.

TABLE C-3 OFFSITE (Control) ENVIRONMENTAL TLD STATIONS Station TLD Exposure Measurements (mR)

Number First Quarter Second Quarter Third Quarter Fourth Quarter 1 13.2 +/- 0.5 Not Required Not Required Not Required 2 15.0 +/- 1.8 Not Required Not Required Not Required 14 12.7 +/- 0.5 Not Required Not Required Not Required 25 12.0 +/- 1.2 Not Required Not Required Not Required T17 12.7 +/- 0.5 Not Required Not Required Not Required Calculated Parameters (mR)

Parameter First Quarter Second Quarter Third Quarter Fourth Quarter Average 13.2 +/- 0.0 Not Required Not Required Not Required Maximum 15.0 +/-1.8 Not Required Not Required Not Required Table C-3 Notes:

1. All decommissioning demolition activities of Unit 3 were complete end of 2019. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.
2. The reported exposures do not have an average background or transient dose subtracted.
3. Not Required: Not required by the HBPP Unit 3 Technical Specifications or the SAFSTOR Offsite Dose Calculation Manual.

Table C-4 ODCM REQUIRED AIR SAMPLES: AM2 NORTH (AM2)

Sample Alpha Activity Beta Activity Composite Gamma Start Date (pCi/m3) (pCi/m3) Activity (pCi/m3)

Co-60 Cs-137 12/31/2019 < 6.42E-04 (MDA) 8.13E-03 +/- 1.43E-03 1/8/2020 < 5.78E-04 (MDA) 4.17E-03 +/- 1.05E-03 1/15/2020 6.71E-04 +/- 5.50E-04 7.18E-03 +/- 1.33E-03 N/A N/A 1/22/2020 < 4.56E-04 (MDA) 5.58E-03 +/- 1.16E-03 1/29/2020 < 7.25E-04 (MDA) 7.10E-03 +/- 1.28E-03 2/5/2020 < 5.26E-04 (MDA) 6.58E-03 +/- 1.32E-03 Table C-4 (Continued)

ODCM REQUIRED AIR SAMPLES: RELAY BUILDING (AM4)

Sample Alpha Activity Beta Activity Composite Gamma Start Date (pCi/m3) (pCi/m3) Activity (pCi/m3)

Co-60 Cs-137 12/31/2019 < 1.09E-03 (MDA) 5.89E-03 +/- 1.26E-03 1/8/2020 < 7.25E-04 (MDA) 4.37E-03 +/- 1.08E-03 1/15/2020 < 7.35E-04 (MDA) 6.08E-03 +/- 1.22E-03 N/A N/A 1/22/2020 < 8.89E-04 (MDA) 5.45E-03 +/- 1.14E-03 1/29/2020 < 5.50E-04 (MDA) 5.71E-03 +/- 1.16E-03 2/5/2020 < 4.39E-04 (MDA) 6.47E-03 +/- 1.22E-03 Table C-4 Notes

1. HBPP onsite count room building, and equipment are demobilized, beginning fourth quarter 2019, all Air samples were sent to GEL for sample analysis.
2. No quarterly composite samples were counted onsite due to demobilization of onsite lab fourth quarter of 2019.
3. ODCM Revision 32, effective February 2020, removes all remaining air sample locations.

FIGURE A-1 HBPP ONSITE AIR SAMPLE LOCATIONS N

AM2 AM4 Location GPS Coordinates (NAD83/NAVD88 CA. Zone 1)

Number Easting Northing North 5949884 2161067 AM2 Relay Bldg.

5949456 2160858 AM4 Figure A-1 Note:

1. ODCM Revision 32 (February 2020) removes all remaining air sample locations.

FIGURE A-2 HBPP ONSITE TLD LOCATIONS Stations T1 - T16 (excluding T17)

T-8 T-7 T-6 T-5 T-9 T-4 T-10 T-11 T-3 T-2 T-1 T-12 T-16 T-14 T-13 T-15 Monitoring Locations T7, T10, T11, T13, T16, T2, T3, and T5 generally represent REMP Site Boundary direct exposure monitoring locations in the 8 primary compass points beginning with T7 representing north and moving clockwise. ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020.

Location GPS Coordinates Number (NAD83/NAVD88 CA Zone 1)

Easting Northing Elevation T1 5949179 2160815 11 T2 5948794 2160911 17 T3 5948610 2161062 42 T4 5948779 2161270 44 T5 5948944 2161301 40 T6 5949140 2161433 36 T7 5949249 2161482 33 T8 5949428 2161435 28 T9 5949478 2161241 23 T10 5949519 2161199 19 T11 5949772 2161202 13 T12 5950019 2160858 11 T13 5949842 2160718 10 T14 5949584 2160684 10 T15 5949473 2160590 11 T16 5949327 2160771 11 FIGURE A-3 HBPP OFFSITE TLD LOCATIONS Stations (1, 14 & 25) t N

GPS Coordlnales (NA083/NAVD88 CA. Zone 1) Degree.Decimal 0 Easting I Northing el. l alilude Longlud~

1 5948026.52 I 2161 183.79 11 .38 40.74156 - 124.21903 14 5949876.83 I 2158864.39 18.65 40.73533 -124.20802 25 5950247.30 I 2154214. 18 229.22

  • 40.72260 -124.20626 FIGURE A-3 (Continued)

HBPP OFFSITE TLD LOCATION FORTUNA (Station 2)

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GPS Coordinates (NAD83/NAVD88 CA, Zone 1) Degree.Decimal Easting I Northina I el. Latitude I Longitude 5962583.86 I 2105797,82 I 35.53 40,59057 I -124: 15746 FIGURE A-3 (Continued)

HBPP OFFSITE TLD LOCATION EUREKA (Control Location T17) i .I I*

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~ t.! t,eJ...,'lof- ....... -

.. _, i"tnls ldtHI GPS C-Oordinates (NA083/NAV08S CA. Zone 11 Degree. Decimal Eastina I Northing I , 1. Latitude I Longitude 5976549.55 I 2175490.19 I 164.85 40.78276 I -1 24.11324 FIGURE B-1 OFFSITE ENVIRONMENTAL RADIATION LEVEL TRENDS 80.0 70.0 60.0 50.0 Dose mRem/yr 40.0 King Salmon Picnic Acea (Station1) 30.0 Fortuna (Station 2) 20.0 South Bay School (Station 14)

Humboldt Hill (Station 25) 10.0 Myrtletown Substation (Station T17) 0.0 Year ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020. First quarter of 2020 TLDs results were multiplied by 4, as an estimate, for comparison to historical data and do not reflect actual measured yearly totals.

The baseline values for each location were obtained by averaging the readings at each location from 1977 through 1983. These values were obtained using ion chambers instead of TLDs. The average annual values from 1977 through 1983 were Station 1 - 83.0 mRem, Station 2 - 79.8 mRem, Station 14 - 80.2 mRem, and Station 25 - 73.7 mRem.

FIGURE B-2 ONSITE ENVIRONMENTAL RADIATION LEVEL TRENDS 70.0 60.0 I I

I I

I I

50.0 I 40.0 30.0 Stations Near Radwaste Activities (T5-T8), 1989-2015 20.0 Other Onsite Stations (T1-T4, T9-T16), 1989-2015 Radwaste handling (T8-T10), 2016-2020 10.0 Other Onsite Stations (T1-T7, T11-T16) 2016-2020 0.0 Year ODCM Revision 32, effective February 2020, eliminated onsite and offsite TLD locations; however, final TLDs were removed at normal quarter end interval on April 1, 2020. First quarter of 2020 TLDs results were multiplied by 4, as an estimate, for comparison to historical data and do not reflect actual measured yearly totals.

The baseline values for the two areas were obtained by averaging the readings for each area from 1977 through 1983. These values, were obtained using ion chambers instead of TLDs. The average annual value from 1977 through 1983 for the stations near the radwaste activities was 78.6 mRem and the average annual value for other onsite stations was 79.4 mRem.

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