HBL-21-016, Request to Terminate the Humboldt Bay Power Plant 10 CFR Part 50 License

Request to Terminate the Humboldt Bay Power Plant 10 CFR Part 50 License

ML21294A421
Person / Time
Site:	Humboldt Bay
Issue date:	10/21/2021
From:	Welsch J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
HBL-21-016
Download: ML21294A421 (14)

Text

mPacHic Gas and Electric Company*

James M. Welsch Senior Vice President Generation and Chief Nuclear Officer Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 805.801.6385 E-Mail: James.Welsch@pge.com PG&E Letter HBL-21-016 ATTN: Document Control Desk U.S Nuclear Regulatory Commission Washington, DC 20555-0001 Docket No. 50-133, License No. DPR-7 Humboldt Bay Power Plant, Unit 3 Request to Terminate the Humboldt Bay Power Plant 10 CFR Part 50 License

References:

1. PG&E Letter HBL-16-008, Request for Partial Release of Humboldt Bay Power Plant Unit 3 Property from the Part 50 Site, dated November 9, 2016 (ML16326A004).

2. NRC Letter to PG&E, Humboldt Bay Power Plant Unit 3 -

Request for Partial Site Release from Part 50 License (CAC No.

L53153), dated January 5, 2018 (ML17115A108 and ML17115A109).

Dear Commissioners and Staff:

In accordance with 10 CFR 50.82(a)(9), Pacific Gas and Electric Company (PG&E) requests that the NRC terminate the Humboldt Bay Power Plant (HBPP) 10 CFR Part 50 License, Number DPR-7. PG&E has completed the final phase of decommissioning and is requesting that the NRC release the HBPP 10 CFR Part 50 licensed facility for unrestricted use.

The NRC approved License Termination Plan (LTP) for HBPP discusses PG&E's phased approach to decommissioning. In Reference 1, PG&E submitted a request for a partial release of approximately 30.4 acres known as the Fisherman's Channel, from the 10 CFR Part 50 License. In Reference 2, the NRC approved the release of this area.

The remaining area to be released includes the remainder of the 10 CFR Part 50 licensed area. PG&E has completed the remaining radiological decommissioning and Final Status Surveys (FSSs) for HBPP in accordance with the NRC approved LTP. The FSS Reports demonstrate that the site meets the criteria for decommissioning and release of the site for unrestricted use in accordance with 10 CFR Part 20, Subpart E, "Radiological Criteria for License Termination." The spent nuclear fuel and Greater than Class C waste remain stored at the Humboldt Bay (HB) Independent Spent Fuel Storage Installation (ISFSI), licensed under 10 CFR Part 72.

Document Control Desk PG&E Letter HBL-21-016 Page 2 PG&E has reviewed the survey area results to ensure that the proposed action will have no adverse impact on the ability of the site, in aggregate, to meet 10 CFR Part 20, Subpart E. Accordingly, PG&E has satisfied the requirements governing termination of a facility license as stated in 10 CFR 50.82(a)(11), and requests that the NRC approve this application and terminate the HBPP 10 CFR Part 50 license. PG&E is submitting this request to terminate contingent upon approval of the remaining FSS Reports currently under NRC review.

The Enclosure provides a summary of the assessment performed for the remaining 10 CFR Part 50 licensed area.

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

If you have any questions or require additional supporting documentation for this submittal, please contact Mr. William Barley at 707-267-0071.

I state under penalty of perjury that the foregoing is true and correct.

Executed on October 21, 2021.

Sincerely, James M. Welsch Senior Vice President, Generation and Chief Nuclear Officer Enclosure cc: HBPP Humboldt Distribution cc/enc: Scott A. Morris, NRC Region IV Administrator Amy M. Snyder, NRC Reactor Decommissioning Branch Project Manager

Enclosure PG&E Letter HBL-21-016 Introduction Humboldt Bay Power Plant (HBPP) Unit 3, located at 1000 King Salmon Avenue, Eureka, California, was a 63 MWe Boiling Water Reactor (BWR). Unit 3 was granted a construction permit by the Atomic Energy Commission (AEC) on October 17, 1960. Operating License DPR-7 was issued in August 1962. The unit began commercial operation in August 1963 and last operated in 1976. In June 1983 Pacific Gas and Electric Company (PG&E) announced its intention to decommission and the unit was permanently defueled in 1984.

PG&E submitted the HBPP Unit 3 Post-Shutdown Decommissioning Activities Report (PSDAR) to NRC on February 27, 1998, in accordance with 10 CFR 50.82 (a)(4)(i). The PSDAR and the Defueled Safety Analysis Report (DSAR) superseded the original Decommissioning Plan and provided the information required by 10 CFR 50.82(a)(4).

On November 17, 2005, the NRC issued Humboldt Bay (HB) Independent Spent Fuel Storage Installation (ISFSI) License SNM-2514 (Docket No. 72-27). Transfer of spent nuclear fuel to the onsite HB ISFSI was completed in December 2008. PG&E began actively decommissioning Unit 3 in June 2009.

As described in the License Termination Plan (LTP), PG&E submitted a request for a partial release of approximately 30.4 acres known as the Fisherman's Channel, from the 10 CFR Part 50 License (Reference 1). In January of 2018, the NRC approved the release of this area (Reference 2). The remaining area to be released includes the remainder of the 10 CFR Part 50 licensed area. PG&E has completed the remaining radiological decommissioning and Final Status Surveys (FSSs) for HBPP in accordance with the NRC approved LTP. PG&E submitted FSS Reports which demonstrated that these remaining areas of the site meet the criteria for decommissioning and release of the site for unrestricted use in accordance with 10 CFR Part 20, Subpart E, "Radiological Criteria for License Termination." As indicated in Table 1 below, the NRC has approved most of the FSS Reports, but a few remain for NRC review and approval. Table 1 provides reference to the PG&E FSS Reports and the corresponding NRC approval. The spent nuclear fuel and Greater than Class C waste remain stored at the HB ISFSI, licensed under 10 CFR Part 72.

Table 1. PG&E FSS Reports and Corresponding NRC Approvals

1. PG&E Submittal NRC Approval 1 PG&E Letter HBL-17-001, Final Status NRC Letter, Humboldt Bay Power Survey Report for New Generation Plant, Unit 3 - Approval of Final Footprint Area, dated March 9, 2017 Status Survey Reports NGFA-EST (ML17068A100) and NGFA-WST, dated June 11, 2018 (ML18155A300)

Enclosure PG&E Letter HBL-21-016

1. PG&E Submittal NRC Approval 2 PG&E Letter HBL-18-008, Final Status NRC Letter, Humboldt Bay Power Survey Report for Mobile Emergency Plant, Unit 3 - Approval of Final Power Plant Station Area (Survey Unit Status Survey Reports for OOL10-OOL10-04), dated July 19, 2018 04 and ISF01-01, dated October 11, (ML18200A248) 2018 (ML18278A087) 3 PG&E Letter HBL-18-009, Final Status NRC Letter, Humboldt Bay Power Survey Report for Independent Spent Plant, Unit 3 - Approval of Final Fuel Storage Installation Area (Survey Status Survey Reports for OOL10-Unit ISF01-01), dated July 19, 2018 04 and ISF01-01, dated October 11, 2018 (ML18278A087) 4 PG&E Letter HBL-19-011, Final Status NRC Letter, Humboldt Bay Power Survey Report for the Relay Building Plant, Unit 3 - Approval of Final (Survey Units RLY01-01 and RLY01-02) Status Survey Reports for the Relay and the MEPPS Island Building (Survey Building and the MEPPS Island Units MEPPS01-01 and MEPPS01-02), Building, dated December 4, 2019 dated May 22, 2019 (ML19143A046) (ML19319B063 and ML19319A566) 5 PG&E Letter HBL-19-014, Final Status NRC Letter, Humboldt Bay Power Survey Report for Six Survey Areas Plant, Unit 3 - Approval of Final Within Survey Unit OOL10, dated Status Survey Reports for Six October 17, 2019 (ML19291A014 and Survey Areas within Survey Unit ML19290H613) OOL10, dated February 12, 2020 (ML20030A099 and ML20030A100) 6 PG&E Letter HBL-20-007, Final Status NRC Letter, Humboldt Bay Power Survey Report for the Humboldt Bay Plant, Unit 3 - Approval of Final Power Plant Reactor Caisson Status Survey Reports for Caisson Survey Units, dated April 1, 2020 Survey Units NOL01-09/

(ML20092M643) NOL01-09-FSR, dated August 3, 2021 (ML21214A100 and ML21214A101) 7 PG&E Letter HBL-20-010, Final Status NRC Letter, Humboldt Bay Power Survey Report for the Humboldt Bay Plant, Unit 3 - Approval of Final Power Plant Trailer City Area, dated May Status Survey Reports for Trailer 21, 2020 (ML20142A287) City Survey Units (OOL09-01 Through OOL09-10), dated August 24, 2021 (ML21225A772 and ML21225A773) 8 PG&E Letter HBL-20-013, Final Status NRC Letter, Humboldt Bay Power Survey Report for the Humboldt Bay Plant, Unit 3 - Approval of Final Power Plant (Office Annex, Status Survey Reports for Office Security Building, Intake Structure, Annex, Security Building, Intake Count Room Building, and Waste Structure, Count Room Building and Management Facility), dated September Waste Management Facility Survey 24, 2020 (ML20268B244) Units, dated August 25, 2021 (ML21225A775 and ML21225A776) 9 PG&E Letter HBL-21-010, Final Status NRC Review

Enclosure PG&E Letter HBL-21-016

1. PG&E Submittal NRC Approval Survey Reports for the Humboldt Bay Power Plant, dated June 8, 2021 (ML21160A224) 10 PG&E Letter HBL-21-011, Final Status NRC Review Survey Report for the Humboldt Bay Power Plant, dated July 13, 2021 (ML21194A441) 11 PG&E Letter, HBL-21-014, Final Status NRC Review Survey Report for the Humboldt Bay Power Plant, dated August 9, 2021 (ML21221A135)

Regulatory Basis for License Termination NRC Regulation 10 CFR 50.82(a)(11) states:

The Commission shall terminate the license if it determines that (i) The remaining dismantlement has been performed in accordance with the approved license termination plan, and (ii) The final radiation survey and associated documentation, including an assessment of dose contributions associated with parts released for use before approval of the license termination plan, demonstrate that the facility and site have met the criteria for decommissioning in 10 CFR part 20, subpart E.

PG&E has satisfied the criteria of 10 CFR 50.82(a)(11)(i and ii), which will allow the NRC to terminate the HBPP 10 CFR Part 50 license. Regarding 10 CFR 50.82(a)(11)(i), PG&E has completed all remaining decommissioning activities, including radioactive waste disposal, dismantlement, decontamination, and final status surveys, in accordance with the NRC approved LTP. Regarding 10 CFR 50.82(a)(11)(ii), the licensed site area has been surveyed and findings indicate that the clearance criteria of 10 CFR 20, Subpart E has been met.

Evaluation Areas to be Released and FSS Results The remaining areas to be released consist of the licensed site area to the plant East of King Salmon Avenue. The final status surveys for this area have been completed in accordance with the LTP, confirmatory surveys have been performed

Enclosure PG&E Letter HBL-21-016 by both the NRC and its contractor, and reports for FSS areas have been submitted to the NRC for review and approval. Those reports indicate that the clearance criteria of 10 CFR 20, Subpart E has been met and once all area reports have been approved by the NRC, the HBPP Unit 3 license may be terminated.

Remaining Decommissioning Activities PG&E has completed all decommissioning and dismantlement activities required to terminate the 10 CFR Part 50 license. In accordance with 10 CFR 20.1402, a site will be considered acceptable for unrestricted use if the residual radioactivity that is distinguishable from background radiation results in a TEDE to an average member of the critical group that does not exceed 25 mrem (0.25 mSv) per year, including that from groundwater sources of drinking water, and the residual radioactivity has been reduced to levels that are as low as reasonably achievable (ALARA). PG&E has met the criteria in 10 CFR 20.1402, Radiological criteria for unrestricted use and the remainder of the HBPP site is suitable to be released for unrestricted use.

Therefore, the 10 CFR Part 50 license can be terminated.

The spent nuclear fuel and greater-than-class-c (GTCC) waste remain stored onsite at the HB ISFSI licensed under 10 CFR Part 72.

Controls to Prevent Recontamination As stated above, PG&E has completed the remaining FSSs for HBPP in accordance with the NRC approved LTP. The FSS reports demonstrate that the HBPP site is well below HBPP's Derived Concentration Guideline Level (DCGLs), and therefore, there is no mechanism to re-contaminate the HBPP site due to any activities at the site. Accordingly, HBPP will continue to meet the criteria for releasing the site for unrestricted use in accordance with 10 CFR Part 20, Subpart E and the released site will continue to meet the radiological criteria for unrestricted release.

The spent nuclear fuel and GTCC waste are stored at the HB ISFSI, in the Holtec HI-STAR HB storage system. The HB ISFSI is designed to protect the stored fuel and prevent release of radioactive material under all normal, off-normal, and accident conditions of storage in accordance with all applicable regulatory requirements contained in 10 CFR 72. Chapter 8 of the HB ISFSI Updated Final Safety Analysis Report analyzes normal, off-normal, or accident conditions that would result in the release of radioactive material to areas that have been released for unrestricted use. Consequently, there is no release of radioactive material from the HB ISFSI.

NRC/EPA Memorandum of Understanding The NRC and the Environmental Protection Agency (EPA) have a memorandum of understanding (MOU), which sets forth the circumstances in which consultation with the EPA is required. The MOU identifies certain radionuclide concentrations against

Enclosure PG&E Letter HBL-21-016 which the average concentrations present at an NRC licensed site at the time of license termination are to be evaluated. These concentrations are for soil and groundwater. Attachment provides an Evaluation of Soil and Groundwater Concentrations Concerning the NRC/EPA MOU.

Impact of Proposed Site Release on Programs and Documents All the HBPP Licensing Basis Documents (LBDs) will be evaluated against the criteria in 10 CFR 50.59 and 10 CFR 72.48. The LBDs associated with the 10 CFR Part 50 license only will be cancelled upon termination of the 10 CFR Part 50 license. The LBDs that are still applicable to the HB ISFSI will be revised to reflect the termination of the Part 50 license and the remaining LBDs will reflect a stand-alone ISFSI. The following LBDs have criteria for requiring prior NRC approval beyond the criteria in 10 CFR 50.59 and 72.48:

Humboldt Bay Quality Assurance Program PG&E maintains an NRC approved Quality Assurance Program that satisfies the requirements of 10 CFR Part 50, Appendix B. In accordance with 10 CFR 71.101(f) and 10 CFR 72.140(d), PG&E also applies this program to satisfy the Quality Assurance (QA) requirements of 10 CFR Part 71, Subpart H and 10 CFR Part 72, Subpart G.

In Reference 3, PG&E submitted for NRC approval a Quality Assurance Plan (QAP) for the HB ISFSI that satisfies the requirements of 10 CFR Part 72, Subpart G and 10 CFR Part 71, Subpart H. In Reference 4, PG&E responded to an NRC request for supplemental information regarding the QAP and informed the NRC that the QAP would be implemented upon termination of the 10 CFR Part 50 license for HBPP. In Reference 5, the NRC approved the HB ISFSI QAP.

Emergency Plan Emergency Plan, Change 9, Revision 10, reflects the termination of the 10 CFR Part 50 license and will become effective upon termination of the 10 CFR Part 50 license. The changes to the Emergency Plan are administrative and include deleting references to 10 CFR Part 50, deleting the Part 50 EPZ, and deleting the Part 50 Emergency Action Levels. These changes do not reduce the effectiveness of the Emergency Plan and therefore, do not require prior NRC approval to implement.

Physical Security Plan The Physical Security Plan (PSP) applies to the 10 CFR Part 72 licensed ISFSI only and is not affected by the termination of the 10 CFR Part 50 license.

Enclosure PG&E Letter HBL-21-016 NRC Inspections and Confirmatory Surveys At the request of the NRC, the Oak Ridge Institute for Science and Education (ORISE), managed by Oak Ridge Associated University (ORAU), performed confirmatory radiation surveys at the HBPP site during various NRC inspections.

The last visit onsite was during August 26-29, 2019. ORISE performed independent confirmatory surveys of the remaining land areas and select buildings. The 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. The report concluded that the confirmatory survey results indicated that the areas surveyed meet the NRC approved criteria for release for unrestricted use.

Conclusions On May 4, 2016, the NRC approved the HBPP LTP and determined that the proposed DCGLs developed for soil, building surfaces, and buried and embedded piping at the site would ensure that the annual dose criterion for unrestricted release in 10 CFR 20.1402 is met (Reference 6). After the initial approval of the LTP, the NRC approved a license amendment to change the methodology from what was previously approved in the LTP for demonstrating compliance with the dose criterion in 10 CFR 20.1402, Radiological criteria for unrestricted use (Reference 7). The FSS Reports are consistent with the LTP and demonstrate compliance with the release criteria. The FSS results demonstrate that the survey areas to be released meet the radiological criteria for unrestricted release.

NRC inspections and confirmatory measurements verified that the decommissioning and FSS programs adequately addressed the radiological conditions at the HBPP site and the remainder of the HBPP site is suitable to be released for unrestricted use. Accordingly, the NRC should approve the termination of the HBPP 10 CFR Part 50 license.

References

1. PG&E Letter HBL-16-008, "Request for Partial Release of Humboldt Bay Power Plant Unit 3 Property from the Part 50 Site," dated November 9, 2016 (ML16326A004)

2. NRC Letter to PG&E, "Humboldt Bay Power Plant Unit 3 -

Request for Partial Site Release from Part 50 License (CAC No. L53153),"

dated January 5, 2018 (ML17115A108 and ML17115A109)

3. PG&E Letter HIL-19-001, Humboldt Bay Independent Spent Fuel Storage Installation Quality Assurance Plan, Revision 0, dated February 14, 2019 (ML19045A700)

4. PG&E Letter HIL-19-010, Response to NRC Request for Supplemental

Enclosure PG&E Letter HBL-21-016 Information for the Humboldt Bay Independent Spent Fuel Storage Installation Quality Assurance Plan, dated September 3, 2019 (ML19247E271)

5. NRC Letter, Safety Evaluation Report for the Pacific Gas and Electric Company Humboldt Bay Independent Spent Fuel Storage Installation Quality Assurance Plan HBI-L6 Revision 0 (CAC No. 001028), dated April 17, 2020 (ML20092L173)

6. NRC Letter, Humboldt Bay Power Plant Unit 3 - Issuance of Amendment RE: License Termination Plan (TAC No. J00485), dated May 4, 2016 (ML15090A339)

7. NRC Letter, Enclosure 2, Safety Evaluation by Office of Nuclear Material Safety and Safeguards Related to Amendment No. 46 to Facility Operating License No. DPR-7 Pacific Gas and Electric Company Humboldt Bay Power Plant, Unit 3 Docket No. 50-133, dated June 24, 2021 (ML21158A137)

Attachment PG&E Letter HBL-21-016 Evaluation of Soil and Groundwater Concentrations Concerning the NRC/EPA MOU

Attachment PG&E Letter HBL-21-016

Background

The Environmental Protection Agency (EPA)/NRC memorandum of understanding (MOU) 1 contains certain radionuclide concentrations against which the average concentrations present at an NRC licensed site at the time of license termination are to be evaluated. These concentrations are for soil and groundwater. The following provides a summary of the actual concentrations for these media at the Humboldt Bay Power Plant (HBPP).

Evaluations Soil Table 1 Nuclides of Concern at HBPP Referenced in EPA/NRC MOU Listing contains 16 radionuclides of concern at HBPP that were listed to be assessed in the listing contained in the EPA/NRC MOU document. Although there were additional radionuclides of concern at HBPP, only those nuclides specifically identified in the EPA/NRC MOU were utilized in performing sum of fractions calculations.

Table 1 Nuclides of Concern at HBPP Referenced in EPA/NRC MOU Listing Radionuclide EPA/NRC MOU Consultation Triggers For Residual Soil Contamination (pCi/g)

H-3 423 C-14 123,000 Co-60 6 Ni-59 1,230,000 Ni-63 555,000 Sr-90+Daughters 1070 Nb-94 3 Tc-99 89,400 Cs-137+Daughter 11 Eu-152 7 Eu-154 8 Pu-238 1,640 Pu-239 1,430 Pu-241 172,000 Am-241 568 1

MEMORANDUM OF UNDERSTANDING BETWEEN THE ENVIRONMENTAL PROTECTION AGENCY AND THE NUCLEAR REGULATORY COMMISSION, CONSULTATION AND FINALITY ON DECOMMISSIONING AND DECONTAMINATION OF CONTAMINATED SITES

Attachment PG&E Letter HBL-21-016 Radionuclide EPA/NRC MOU Consultation Triggers For Residual Soil Contamination (pCi/g)

Cm-243 67 An analysis of the surface soil sample results from 61 radiological Final Status Survey (FSS) units were utilized to calculate a sum of fractions for the 16 nuclides listed in Table 1. For gamma emitters listed in Table 1, there was a statistically significant number of samples to obtain a greater than 95 percent confidence result.

For non-gamma emitters, the lesser number of samples analyzed were utilized to best represent an estimate of the contribution for those nuclides. The surface soil sample results for each nuclide in each FSS unit were averaged and the average results for the 16 nuclide used to estimate the sum of fractions for the EPA/NRC MOU at HBPP. Table 2 contains the sum of fraction calculations for these 16 nuclides in the listed 61 FSS units.

Table 2: NRC-EPA MOU Sum of Fractions for Survey Units at Humboldt Bay Power Plant Decommissioning As Left Surface Conditions Survey Unit Sum of Survey Unit Sum of Fractions Fractions OOL10-11 Fisherman's 1.07E-02 OOL08-06 Area W. of Bldg -1.06E-02 25 OOL10-12 Fisherman's 1.84E-02 OOL04-01 Sump Drain Line 4.38E-03 Area NGFA-EST (HBGS) 2.51E-03 OOL10-18 New Gen. 1.25E-03 Boundary Area NGFA-WST (HBGS) 2.18E-03 OOL10-25 Decom Facility 2.91E-02 Area OOL10-04 (MEPPS area) 9.86E-03 OOL02-02 Intake Structure 1.87E-03 Area ISF01-01 (ISFSI) -1.31E-03 OOL11-01 Intake Canal -2.30E-02 West OOL10-05 (Circ Water) -5.12E-03 OOL02-01 Intake Canal 5.76E-02 East OOL10-06 (60 Kv) FSS 8.55E-03 OOL06-01 Intake Canal 1.91E-02 Center OOL10-14 (Parking Lot A) -8.77E-04 OOL01-01 Discharge Canal 1.98E-02 North OOL10-15 Buhne Slough 3.82E-02 OOL01-02 Discharge Canal 2.64E-03 Middle OOL10-23 Humboldt Bay 4.89E-03 OOL01-03 Discharge Canal 2.42E-02 South OOL10-19 Area East of 1.05E-02 OOL07-01 Canal West 1.89E-02 Trailer City Bank North

Attachment PG&E Letter HBL-21-016 Survey Unit Sum of Survey Unit Sum of Fractions Fractions NOL01-09 Caisson -1.04E-02 OOL07-02 Canal West 1.64E-02 Bank South OOL09-01 Discharge Canal 2.50E-03 OOL07-03 Area 51 South -1.71E-02 North OOL09-02 Settling Basin 6.89E-03 OOL07-04 Area 51 North 1.57E-03 OOL09-03 SMF West 7.70E-04 OOL05-01 Discharge Canal -8.89E-03 at Bay OOL09-04 SMF East 5.34E-03 OOL10-01 LFO Area 1.50E-02 OOL09-05 Bull Pen West 2.97E-03 OOL10-13 Coastal Trail 2.72E-02 OOL09-06 Bull Pen East -8.72E-05 OOL10-17 Bravo Road & 9.53E-03 Frog Pond OOL09-07 GWTS North 8.60E-03 OOL10-20 Haul Roads 2.22E-02 OOL09-08 GWTS South 6.61E-03 OOL10-22 ISFSI West 2.33E-02 OOL09-09 Asbestos Area 4.10E-04 OOL10-24 WMF Pad 5.64E-03 OOL09-10 Trail Buffer Zone 5.82E-03 OOL10-26 Charlie Road 7.15E-03 OOL03-01 Land Area U1 2.26E-03 NOL01-01 RUBB Tent Area 3.32E-02 OOL03-02 Land Area U2 -1.09E-02 NOL01-02 Upper Yard -1.03E-02 OOL08-01 Open Land Area 1.67E-03 NOL01-03 Upper Yard 2.97E-03 U1 South OOL08-02(Bldg. 5 Footprint 1.16E-02 NOL01-04 East Yard 5.95E-03 OOL08-03 Bldg. 26 Walkway 1.42E-02 NOL01-05 North Yard 4.64E-03 OOL08-04 Engr Trls. S. of 4.43E-03 NOL01-06 HMS Footprint 2.25E-03 Bldg. 25 OOL08-05 Bldg. 25 Area 4.94E-04 NOL01-07 Turbine Bldgs. -7.38E-03 Footprint NOL01-08 Balance of East 1.83E-03 Yard Water During the time of operation of HBPP, as a result of spent fuel pool leakage, concentrations of radionuclides were detected in groundwater monitoring wells. As a result, HBPP installed a liner in the spent fuel pool and maintained a level between the liner and spent fuel pool wall to prevent further leakage to the groundwater.

As a result of those actions, past groundwater contamination decreased through both dilution and decay such that no HBPP related radionuclide groundwater contamination had been detected for decades before start of active decommissioning. Due to potential for cross contamination from decommissioning activities groundwater monitoring was continued during the active decommissioning until such time that primarily site restoration activities remained. During both the pre-active decommissioning during SAFSTOR and active decommissioning, no

Attachment PG&E Letter HBL-21-016 HBPP related radionuclide groundwater contamination was identified.

Results Since all sum of fractions calculations were significantly less than 1 with a highest amount of 5.76E-02, no EPA trigger values were reached from surface soil sample analysis at HBPP. As described above, since no HBPP related nuclide contamination was detected in groundwater prior to or during active decommissioning at HBPP, no trigger value was reached for groundwater.