ML24340A216

Independent Spent Fuel Storage Installation - Decommissioning Funding Plan

ML24340A216
Person / Time
Site:	Humboldt Bay
Issue date:	12/05/2024
From:	Zawalick M Pacific Gas & Electric Co
To:	Office of Nuclear Material Safety and Safeguards, Document Control Desk
References
HIL-24-008
Download: ML24340A216 (1)

Text

Maureen R. Zawalick Vice President Generation Business and Technical Services Diablo Canyon Power Plant Mail code 104/6/608 P.O. Box 56 Avila Beach, CA 93424 805.545.4242 Internal: 691.4242 PG&E Letter HIL-24-008 ATTN: Document Control Desk 10 CFR 72.30 Director, Division of Spent Fuel Storage and Transportation Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Docket No. 72-27, Materials License No. SNM-2514 Humboldt Bay Independent Spent Fuel Storage Installation Decommissioning Funding Plan

Dear Commissioners and Staff:

In accordance with the requirements of 10 CFR 72.30, Financial assurance and recordkeeping for decommissioning, a decommissioning funding plan (DFP) in 2024 dollars is hereby submitted in this letter and enclosures. PG&E is submitting this DFP for NRC review and approval in accordance with 10 CFR 72.30(b) and 10 CFR 72.30(c). addresses the specific requirements of 10 CFR 72.30(c). contains the cost estimate details that support the total Humboldt Bay Independent Spent Fuel Storage Installation (ISFSI) decommissioning cost estimate and includes the funding assumptions used to determine the Humboldt Bay ISFSI decommissioning costs. Enclosure 2 and information contained in this letter address the requirements in 10 CFR 72.30(b) and as demonstrated, there remains reasonable assurance that funds will be available to decommission the Humboldt Bay ISFSI.

PG&E makes no new or revised regulatory commitment (as defined by NEI 99-04) in this letter.

If you have any questions in regard to this document, please contact Mr. Philippe Soenen at (805) 459-3701.

Sincerely, Maureen R. Zawalick Date December 5, 2024

Document Control Desk Page 2 PG&E Letter HIL-24-008 Enclosures cc:

Humboldt Distribution cc/enc: Kristina L. Banovac, NMSS Project Manager John D. Monninger, NRC Region IV Administrator PG&E Letter HIL-24-008 PG&ES RESPONSE TO THE FOUR EVENTS IN 10 CFR 72.30(c)

PG&E Letter HIL-24-008 Page 1 of 2 The four events in 10 CFR 72.30(c) are identified below, as well as Pacific Gas and Electric Companys (PG&Es) response to each event.

The decommissioning funding plan must specifically consider the effect of the following events on decommissioning costs:

(1) Spills of radioactive material producing additional residual radioactivity in onsite subsurface material.

PG&E Response: There have not been any spills of radioactive material in the Humboldt Bay Independent Spent Fuel Storage Installation (ISFSI) area that is surrounded by the ISFSI security boundary fence. Furthermore, the all-welded construction of the multi-purpose containers (MPCs) in conjunction with the extensive inspections and testing performed during closing operations ensures that no release of radioactive effluents will occur.

The Humboldt Bay ISFSI Final Safety Analysis Report (FSAR), Section 7.3.1, states that there are no radioactive systems at the ISFSI other than the greater than Class C (GTCC) cask and overpacks containing MPCs. FSAR Section 7.3.1 further states, The fuel is stored dry inside the MPC so that no radioactive liquid is available for leakage.

In the NRC Safety Evaluation Report (SER) dated November 2005, Section 13.1.2.1, the NRC concurred with PG&Es assessment that the Humboldt Bay ISFSI design will minimize contamination and facilitate decommissioning. The SER states, The confinement design of the MPCs and the passive design of the storage system, minimize the potential for radioactive contamination to occur and to spread.

(2) Facility modifications.

PG&E Response: There have been no modifications to the Humboldt Bay ISFSI vault design that could impact decommissioning costs, and no modifications are expected in the future. See response to item (3) below for more details.

(3) Changes in authorized possession limits.

PG&E Response: The Humboldt Bay ISFSI vault design consists of five storage casks containing spent fuel, and one storage cask containing GTCC waste. The five spent fuel casks have been loaded into the ISFSI vault with spent fuel from the Humboldt Bay Power Plant Unit 3 (HBPP).

HBPP has been decommissioned and no more spent fuel will be generated. The GTCC waste cask has been loaded into the ISFSI vault with GTCC waste that was generated in the operation of HBPP. There will be no additional spent fuel PG&E Letter HIL-24-008 Page 2 of 2 casks nor GTCC waste casks placed in the Humboldt Bay ISFSI beyond that of the original design.

(4) Actual remediation costs that exceed the previous cost estimate.

PG&E Response: PG&E will not begin to decommission the Humboldt Bay ISFSI until after the U.S. Department of Energy takes possession of the spent fuel and GTCC waste. Currently, this is estimated to begin in 2031. Therefore, there have been no actual remediation costs that exceed previous cost estimates.

Although the California Public Utilities Commission (CPUC) typically requires PG&E to update the ISFSI decommissioning cost estimate every three years, PG&E was authorized in D.23-09-004 to defer the filing of its next Nuclear Decommissioning Cost Triennial Proceeding Application to no later than July 1, 2027. If a revised cost estimate exceeds a previous cost estimate, PG&E will submit a request to the CPUC requesting approval of increased funding based on a justifiable reason. In the NRC SER dated November 2005, Section 13.1.1.2, the NRC concludes that the CPUC will likely approve justifiable requests for additional rate recovery as necessary to fully fund the decommissioning trust for circumstances that could not be foreseen or reasonably avoided by PG&E.

PG&E Letter HIL-24-008 Page 1 of 8 10 CFR 72.30 HUMBOLDT BAY INDEPENDENT SPENT FUEL STORAGE INSTALLATION DECOMMISSIONING COST ESTIMATE

1.

Background and Introduction On December 15, 2003, Pacific Gas and Electric Company (PG&E) submitted a license application to construct and operate the Humboldt Bay ISFSI. The license application included a Preliminary Decommissioning Plan as required by 10 CFR 72.30, which included a decommissioning funding plan (DFP) meeting the requirements of 10 CFR 72.30(c) at that time. The DFP stated PG&E has established external sinking fund accounts for decommissioning the Humboldt Bay Power Plant Unit 3 (HBPP) as well as the Humboldt Bay ISFSI, and that assurance of funds was reported in an annual decommissioning funding report dated March 27, 2003, in accordance with 10 CFR 50.75(f). Financial assurance for decommissioning the Humboldt Bay ISFSI is provided by an external sinking fund in accordance with 10 CFR 50.75(e)(1)(ii).

Following review of the license application, the NRC issued a Safety Evaluation Report (SER), dated November 2005. SER Section 13.1.1.2, Financial Qualifications for Humboldt Bay ISFSI, concluded (1) PG&Es estimate of costs to construct, operate and decommission the ISFSI are reasonable, and (2)

PG&Es spent fuel management program for the Humboldt Bay ISFSI provides reasonable assurance that sufficient funds are available to build, operate and decommission the ISFSI.

SER Section 13.1.1.2 also addressed the possible shortfall of funds and determined PG&E would request rate recovery from the California Public Utilities Commission (CPUC) if necessary. The NRC also concluded that the CPUC would likely approve justifiable PG&E requests for additional rate recovery for circumstances that could not be foreseen or reasonably avoided by PG&E. In addition, the NRC concluded that PG&E will adequately maintain segregation of decommissioning funds between HBPP and the Humboldt Bay ISFSI. To ensure segregation of funds, PG&E has established unique accounting for tracking ISFSI related work.

The Nuclear Regulatory Commission (NRC) issued its final rule on Decommissioning Planning on June 17, 2011,[1] with the rule becoming effective on December 17, 2012. Subpart 72.30, Financial assurance and recordkeeping 1

U.S. Code of Federal Regulations, Title 10, Parts 20, 30, 40, 50, 70 and 72 "Decommissioning Planning,"

Nuclear Regulatory Commission, Federal Register Volume 76, Number 117 (p 35512 et seq.), June 17, 2011

PG&E Letter HIL-24-008 Page 2 of 8 for decommissioning, requires that each holder of, or applicant for, a license under this part must submit for NRC review and approval a decommissioning funding plan that contains information on how reasonable assurance will be provided that funds will be available to decommission the Independent Spent Fuel Storage Installation (ISFSI).

In accordance with the rule, this letter provides a detailed cost estimate for decommissioning the ISFSI at Humboldt Bay Power Plant Unit 3 (HBPP3) in an amount reflecting:

1. the work is performed by an independent contractor;

2. an adequate contingency factor; and

3. release of the facility and dry storage systems for unrestricted use, as specified in 10 CFR Part 20.1402.

This letter also provides:

1. identification of the key assumptions contained in the cost estimate; and

2. the volume of onsite subsurface material containing residual radioactivity, if any, that will require remediation to meet the criteria for license termination.

2.

Spent Fuel Management Strategy HBPP3 shut down on July 2, 1976, and has been decommissioned. All of the spent fuel generated during operations, 390 spent fuel assemblies, are currently in storage in the on-site ISFSI. The ISFSI is operated under a Part 72 Site Specific License.

Completion of the ISFSI decommissioning process is dependent upon the Department Of Energys (DOEs) ability to remove spent fuel and Greater than Class C (GTCC) waste from the site. DOEs repository program assumes that spent fuel allocations will be accepted for disposal from the nations commercial nuclear plants, with limited exceptions, in the order (the queue) in which it was discharged from the reactor.[2] Pacific Gas and Electrics (PG&Es) current spent fuel management plan for the HBPP3 spent fuel is based in general upon: 1) a 2031 start date for DOE initiating transfer of commercial spent fuel to a federal facility, and 2) completion of spent fuel receipt by year 2032.

2 U.S. Code of Federal Regulations, Title 10, Part 961.11, Article IV - Responsibilities of the Parties, B. DOE Responsibilities, 5.(a) DOE shall issue an annual acceptance priority ranking for receipt of SNF and/or HLW at the DOE repository. This priority ranking shall be based on the age of SNF and/or HLW as calculated from the date of discharge of such materials from the civilian nuclear power reactor. The oldest fuel or waste will have the highest priority for acceptance, except as

PG&E Letter HIL-24-008 Page 3 of 8

3.

ISFSI Decommissioning Strategy At the conclusion of the spent fuel transfer process the ISFSI will be promptly decommissioned (similar to the power reactor DECON alternative) by removing and disposing of residual radioactivity and verifying that remaining materials satisfy NRC release criteria.

For purposes of providing an estimate for a funding plan, financial assurance is expected to be provided on the basis of a prompt ISFSI decommissioning scenario. In this estimate the ISFSI decommissioning is considered an independent project, regardless of the decommissioning alternative identified for the nuclear power plant.

4.

ISFSI Description The HBPP3 ISFSI is a unique design. Spent fuel is stored in the Holtec International (Holtec) HI-STAR HB system, located inside an underground steel-lined concrete vault. The HI-STAR HB system is comprised of an all-welded multi-purpose canister (MPC-HB) designed to store up to 80 HBPP fuel assemblies inside a bolted-lid steel overpack. The HI-STAR HB system is a shortened version of the HI-STAR 100 System. The system is designed such that both the MPC and steel overpack are expected to be transferred to the DOE at the time of spent fuel transfer. As a result there are not expected to be any remaining HI-STAR overpacks at the time of decommissioning.

PG&Es spent fuel management project for the HBPP3 spent fuel has resulted in 390 spent fuel assemblies being placed in 5 HI-STAR HB storage casks.

In addition to the spent fuel casks located in the ISFSI vault after shutdown there is one additional cask used for GTCC waste storage. The storage overpack used for this GTCC waste canister is expected to be transferred to the DOE at the time of GTCC waste and spent fuel transfer.

The cask storage vault is comprised of six below-grade, cylindrical storage cells that are structural units constructed of steel-reinforced concrete with a carbon steel liner. Each storage cell is approximately 9 feet in diameter by 11 feet, 7 inches deep. The vault bottom is 3 feet thick reinforced concrete. There is an approximate 7 feet thickness of concrete on each end of the vault and 5-1/2 feet on the longitudinal sides of the vault. The concrete wall thickness varies around the circumference of the storage cells and has a minimum thickness of approximately 1 foot - 9 inches of concrete between adjacent cells. Each of the storage cells accommodates one cask (either a loaded HI-STAR HB overpack or the GTCC cask). The top of the vault elevation (without the storage cell lids installed) is approximately flush with grade. The lids are approximately 16-1/4 inches high, not including the height of the lid bolt caps.

The remaining vault structure is not expected to contain residual radioactivity.

PG&E Letter HIL-24-008 Page 4 of 8 Table 1 provides the significant quantities and physical dimensions used as the basis in developing the ISFSI decommissioning estimate.

5.

Key Assumptions / Estimating Approach The decommissioning estimate is based on the configuration of the ISFSI expected after all spent fuel, GTCC waste and storage overpacks have been removed from the site, and the assumptions associated with DOEs spent fuel acceptance, as previously described.

Since HBPP3 is not operating, and all spent fuel is currently in storage, the current configuration of the ISFSI vault is the expected configuration at the time of decommissioning. The nominal vault dimensions (concrete poured areas) are approximately 20 feet in width, and 77 feet in length.

The decommissioning estimate is based on the premise the steel overpack will be transferred to the DOE along with the spent fuel and GTCC waste.

It is not expected that the remaining storage cell surfaces will have any interior radioactive surface contamination. This assumption would be confirmed as a result of good radiological practice of surveying potentially impacted areas after each spent fuel transfer campaign. Any neutron activation of the steel and concrete is expected to be extremely small. To validate this assumption, the estimate accounts for the characterization of two of the storage cells; it is likely that some of this characterization will take place before the last of the fuel is removed from the ISFSI in order to establish a more definitive decommissioning scope.

It is not expected that there will be any residual contamination left on any exterior surfaces of the concrete vault. It is expected that this assumption would be confirmed as a result of good radiological practice of surveying potentially impacted areas after each spent fuel and GTCC waste transfer campaign.

Therefore, it is assumed for this analysis that the ISFSI vault will not be contaminated.

There is no known subsurface material in the proximity of the ISFSI area containing residual radioactivity that will require remediation to meet the criteria for License Termination.

To support an application for License Termination, the estimate assumes that a Final Status Survey will be performed. This will likely include a 100 percent survey of the concrete storage cell and lid surfaces, and a significant fraction of the immediate area surrounding the vault.

PG&E Letter HIL-24-008 Page 5 of 8 For the purposes of meeting 10 CFR 20.1402 requirements, only the costs of characterizations and surveys are included in the decommissioning cost estimates because of the expected absence of radioactive material and need for remediation.

Decommissioning is assumed to be performed by an independent contractor. As such, essentially all contractor labor, equipment, and material costs are based on national averages, i.e., costs from national publications such as R.S. Means Building Construction Cost Data (adjusted for regional variations), and laboratory service costs are based on vendor price lists. Those craft labor positions that are expected to be provided locally, are consistent with fully burdened contractor labor rates used in the Diablo Canyon decommissioning cost estimate, escalated to 2024 dollars. These craft labor rates are assumed to be representative of contractor rates charged in the Humboldt Bay geographical area. PG&E, as licensee, will oversee the site activities; the estimate includes PG&Es labor and overhead costs.

Costs are reported in 2024 dollars.

Contingency has been added at an overall rate of 25 percent. This is consistent with the contingency evaluation criteria referenced by the NRC in NUREG-1757.[3]

The estimate is limited to costs necessary to terminate the ISFSIs NRC license and meet the §20.1402 criteria for unrestricted use. Disposition of released non-contaminated material and structures is outside the scope of the estimate.

6.

Cost Estimate The estimated cost to decommission the ISFSI and release the facility for unrestricted use is provided in Table 2. The cost has been organized into three phases, including:

• An initial planning phase - Empty storage cells are characterized.

• The remediation phase - There is no expected remediation therefore the estimate does not include any costs during this phase.

• The final phase - License termination surveys, independent surveys are completed, and an application for license termination submitted.

3 Consolidated Decommissioning Guidance, Financial Assurance, Recordkeeping, and Timeliness, U.S.

Nuclear Regulatory Commissions Office of Nuclear Material Safety and Safeguards, NUREG-1757, Volume 3, Revision 1, February 2012

PG&E Letter HIL-24-008 Page 6 of 8 In addition to the direct costs associated with a contractor providing the decommissioning services, the estimate also contains costs for the NRC (and NRC contractor), PG&Es oversight staff, site security (industrial), and other site operating costs.

For estimating purposes it should be conservatively assumed that all expenditures will be incurred in the year 2033, the year following all spent fuel removal.

PG&E Letter HIL-24-008 Page 7 of 8 Table 1 Significant Quantities and Physical Dimensions ISFSI Vault Item Length (ft)

Width (ft)

Residual Radioactivity ISFSI Vault 77 20 No ISFSI Storage Cell Item Value Notes (all dimensions are nominal)

Overall Height (inches) 160 From base of cell to the top of the lid Diameter (inches) 107 Inner diameter of storage cell Lid Diameter (inches) 120 Lid Thickness (inches) 16 Quantity (total) 6 Spent Fuel (5) GTCC (1)

Quantity (with residual radioactivity) 0 Surface Area of an Individual Storage Cell and Lid (square feet) 570 PG&E Letter HIL-24-008 Page 8 of 8 Table 2 ISFSI Decommissioning Costs1 and Waste Volumes Waste Volume Person-Hours Removal Packaging Transport Disposal Other Total2 (ft3)

Contractor Licensee NRC / NRC Contractor Decommissioning Contractor Planning (characterization, specs and procedures) 93.1 93.1 312 Decontamination (no expected remediation)

License Termination (radiological surveys) 548.6 548.6 3,098 Subtotal 641.6 641.6 3,410 Supporting Costs NRC and NRC Contractor Fees and Costs 143.6 143.6 536 Insurance 30.7 30.7 Security (industrial) 80.3 80.3 1,881 PG&E Oversight Staff 215.4 215.4 1,881 Subtotal 469.9 469.9 1,881 1,881 536 Total (w/o contingency) 1,111.6 1,111.6 5,291 1,881 536 Total (w/25% contingency) 1,389.5 (thousands, 2024 dollars)

Note 1: For funding planning purposes decommissioning costs can be assumed to be incurred in year 2033 Note 2: Columns may not add due to rounding