Licenses; Exemptions, Applications, Amendments, etc.: Tennessee Valley Authority, Watts Bar Nuclear Plant, Units 1 and 2, Independent Spent Fuel Storage Installation

Tennessee Valley Authority; Watts Bar Nuclear Plant, Units 1 and 2; Independent Spent Fuel Storage Installation; Exemption

Dates

The exemption was issued on April 17, 2024.

Supplementary Information

The text of the exemption is attached.

Attachment-Exemption.

NUCLEAR REGULATORY COMMISSION

Docket Nos. 72-1048, 50-390, and 50-391

Tennessee Valley Authority; Watts Bar Nuclear Plant Units 1 and 2; Independent Spent Fuel Storage Installation

I. Background

Tennessee Valley Authority (TVA) is the holder of Facility Operating License Nos. NPF-90 and NPF-96, which authorize operation of the Watts Bar Nuclear Plant (WBN), Units 1 and 2 in Rhea County, Tennessee, pursuant to Part 50 of Title 10 of the Code of Federal Regulations (10 CFR), "Domestic Licensing of Production and Utilization Facilities." The licenses provide, among other things, that the facility is subject to all rules, regulations, and orders of the U.S. Nuclear Regulatory Commission (NRC) now or hereafter in effect.

Consistent with 10 CFR part 72, subpart K, "General License for Storage of Spent Fuel at Power Reactor Sites," a general license is issued for the storage of spent fuel in an Independent Spent Fuel Storage Installation (ISFSI) at power reactor sites to persons authorized to possess or operate nuclear power reactors under 10 CFR part 50. TVA is authorized to operate nuclear power reactors under 10 CFR part 50 and holds a 10 CFR part 72 general license for storage of spent fuel at the WBN ISFSI. Under the terms of the general license, TVA stores spent fuel at its WBN ISFSI using the HI-STORM Flood/Wind (FW) Multi-Purpose Canister (MPC) Storage System in accordance with Certificate of Compliance (CoC) No. 1032, Amendment No. 0, Revision No. 1.

II. Request/Action

By a letter dated February 28, 2024 (Agencywide Documents Access and Management System [ADAMS] Accession No. ML24059A369), and supplemented on March 18, 2024 (ML24078A257), TVA requested an exemption from the requirements of 10 CFR 72.212(a)(2), 72.212(b)(3), 72.212(b)(5)(i), 72.212(b)(11), and 72.214 that require WBN to comply with the terms, conditions, and specifications of the CoC No. 1032, Amendment No. 0, Revision No. 1 (ML16112A309). If approved, TVA's exemption request would accordingly allow WBN to load MPCs with continuous basket shims (CBS) ( i.e., MPC-37-CBS), an unapproved, variant basket design, in the HI-STORM FW MPC Storage System, and thus, to load the systems in a storage condition where the terms, conditions, and specifications in the CoC No. 1032, Amendment No. 0, Revision No. 1 are not met.

TVA currently uses the HI-STORM FW MPC Storage System under CoC No. 1032, Amendment No. 0, Revision No. 1, for dry storage of spent nuclear fuel in MPC-37 at the WBN ISFSI. Holtec International (Holtec), the designer and manufacturer of the HI-STORM FW MPC Storage System, developed a variant of the design with CBS for the MPC-37, known as MPC-37-CBS. Holtec performed a non-mechanistic tip-over analysis with favorable results and implemented the CBS variant design under the provisions of 10 CFR 72.48, "Changes, tests, and experiments," which allows licensees to make changes to cask designs without a CoC amendment under certain conditions (listed in 10 CFR 72.48(c)). After evaluating the specific changes to the cask designs, the NRC determined that Holtec erred when it implemented the CBS variant design under 10 CFR 72.48, as this is not the type of change allowed without a CoC amendment. For this reason, the NRC issued three Severity Level IV violations to Holtec (ML24016A190).

TVA's near-term loading campaign for the WBN ISFSI includes plans to load five MPC-37-CBS in the HI-STORM FW MPC Storage System beginning in July 2024. While Holtec was required to submit a CoC amendment to the NRC to seek approval of the CBS variant design, such a process will not be completed in time to inform decisions for this near-term loading campaign. Therefore, TVA submitted this exemption request in order to allow for future loading of five MPC-37-CBS beginning in July 2024 at the WBN ISFSI. This exemption is limited to the use of MPC-37-CBS in the HI-STORM FW MPC Storage System only for the specific near-term planned loading of five canisters using the MPC-37-CBS variant basket design.

III. Discussion

Pursuant to 10 CFR 72.7, "Specific exemptions," the Commission may, upon application by any interested person or upon its own initiative, grant such exemptions from the requirements of the regulations of 10 CFR part 72 as it determines are authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest.

A. The Exemption Is Authorized by Law

This exemption would allow TVA to load five MPC-37-CBS in the HI-STORM FW MPC Storage System, beginning July 2024, at its WBN ISFSI in a storage condition where the terms, conditions, and specifications in the CoC No. 1032, Amendment No. 0, Revision No. 1, are not met. WBN is requesting an exemption from the provisions in 10 CFR part 72 that require the licensee to comply with the terms, conditions, and specifications of the CoC for the approved cask model it uses. Section 72.7 allows the NRC to grant exemptions from the requirements of 10 CFR part 72. This authority to grant exemptions is consistent with the Atomic Energy Act of 1954, as amended, and is not otherwise inconsistent with NRC's regulations or other applicable laws. Additionally, no other law prohibits the activities that would be authorized by the exemption. Therefore, the NRC concludes that there is no statutory prohibition on the issuance of the requested exemption, and the NRC is authorized to grant the exemption by law.

B. The Exemption Will Not Endanger Life or Property or the Common Defense and Security

This exemption would allow TVA to load five MPC-37-CBS in the HI-STORM FW MPC Storage System, beginning July 2024, at the WBN ISFSI in a storage condition where the terms, conditions, and specifications in the CoC No. 1032, Amendment No. 0, Revision No. 1, are not met. In support of its exemption request, TVA asserts that issuance of the exemption would not endanger life or property because a tip-over or handling event is administratively controlled, and that the containment boundary would be maintained in such an event. TVA relies, in part, on the approach in the NRC's Safety Determination Memorandum (ML24018A085). The NRC issued this Safety Determination Memorandum to address whether, with respect to the enforcement action against Holtec regarding this violation, there was any need to take an immediate action for the cask systems that were already loaded with non-compliant basket designs. The Safety Determination Memorandum documents a risk-informed approach concluding that, during the design basis event of a non-mechanistic tip-over, the fuel in the basket in the MPC-37-CBS remains in a subcritical condition.

TVA also provided site-specific technical information, as supplemented, including information explaining why the use of the approach in the NRC's Safety Determination Memorandum is appropriate for determining the safe use of the CBS variant baskets at the WBN ISFSI. Specifically, TVA described that the analysis of the tip-over design basis event that is relied upon in the NRC's Safety Determination Memorandum, which demonstrates that the MPC confinement barrier is maintained, is documented in the updated final safety analysis report (UFSAR) for the HI-STORM FW MPC Storage System CoC No. 1032, Amendment 0, Revision No. 1 that is used at the WBN site. TVA stated the transporter for handling of the HI-STORM FW MPC Storage System at the WBN ISFSI has redundant drop protection features and was designed, fabricated, and tested in accordance with the applicable codes described in the CoC No. 1032.

Additionally, TVA provided specific information from WBN's 72.212 Evaluation Report, Revision 5, indicating the calculated total values for annual dose to any real individual who is located beyond the controlled area are shown to be well below the limits required by 10 CFR 72.104(a), "Criteria for radioactive materials in effluents and direct radiation from an ISFSI or MRS." The analysis of a design basis accident scenario also demonstrates compliance with 72.106, "Controlled area of an ISFSI or MRS." Specifically, TVA described that, in the highly unlikely event of a tip-over, any potential fuel damage from a non-mechanistic tip-over event would be localized, the confinement barrier would be maintained, and the shielding material would remain intact. Coupled with the distance of the WBN ISFSI to the site area boundary, TVA concluded that compliance with 72.104 and 72.106 is not impacted by approving this exemption request.

The NRC staff reviewed the information provided by TVA and concludes that issuance of the exemption would not endanger life or property because the administrative controls TVA has in place at the WBN ISFSI sufficiently minimize the possibility of a tip-over or handling event, and that the containment boundary would be maintained in such an event. The staff confirmed that these administrative controls comply with the technical specifications and UFSAR for the HI-STORM FW MPC Storage System CoC No. 1032, Amendment 0, Revision No. 1 that is used at the WBN site. In addition, the staff confirmed that the information provided by TVA regarding WBN's 72.212 Evaluation Report, Revision 5, demonstrates that the consequences of normal and accident conditions would be within the regulatory limits of the 10 CFR 72.104 and 10 CFR 72.106. The staff also determined that the requested exemption is not related to any aspect of the physical security or defense of the WBN ISFSI; therefore, granting the exemption would not result in any potential impacts to common defense and security.

For these reasons, the NRC staff has determined that under the requested exemption, the storage system will continue to meet the safety requirements of 10 CFR part 72 and the offsite dose limits of 10 CFR part 20 and, therefore, will not endanger life or property or the common defense and security.

C. The Exemption Is Otherwise in the Public Interest

The proposed exemption would allow WBN to load five MPC-37-CBS in the HI-STORM FW MPC Storage System beginning in July 2024, at the WBN ISFSI, even though the CBS variant basket design is not part of the approved CoC No. 1032, Amendment No. 0, Revision No. 1. According to TVA, the exemption is in the public interest because not being able to load fuel into dry storage in the future loading campaign would impact TVA's ability to offload fuel from the WBN reactor units, consequently impacting continued safe reactor operation.

TVA stated that to delay the future loading would impact the ability to effectively manage the margin to full core discharge reserve in the WBN Unit 1 and Unit 2 spent fuel pools. WBN's upcoming loading campaign was originally scheduled to begin on January 29, 2024, but was postponed until July 2024 . Any further delay would lead to insufficient space in the spent fuel pool for core offload and the shutdown of WBN Unit 2, which in turn would potentially impact the energy supply in the area. According to TVA, the planned July 2024 loading campaign is the latest, and only opportunity for cask loading to avoid loss of full core reserve in 2025.

For the reasons described by TVA in the exemption request, the NRC agrees that it is in the public interest to grant the exemption. If the exemption is not granted, in order to comply with the CoC, WBN would have to keep spent fuel in the spent fuel pool if it is not permitted to be loaded into casks for future loading. This would impact the ability to manage the margin for full core reserve in the WBN spent fuel pool. Increased inventory in the spent fuel pool would likely require additional fuel moves, which could in turn increase dose to workers and the risk of accidents during fuel handling operations. Moreover, once the spent fuel pool capacity is reached, the ability to refuel the operating reactor is limited, thus affecting continued reactor operations. As described by TVA, this scenario would possibly result in the shutdown of one unit, which could potentially impact the energy supply in the area.

Therefore, the staff concludes that approving the exemption is in the public interest.

Environmental Consideration

The NRC staff also considered whether there would be any significant environmental impacts associated with the exemption. For this proposed action, the NRC staff performed an environmental assessment pursuant to 10 CFR 51.30. The environmental assessment concluded that the proposed action would not significantly impact the quality of the human environment. The NRC staff concluded that the proposed action would not result in any changes in the types or amounts of any radiological or non-radiological effluents that may be released offsite, and there would be no significant increase in occupational or public radiation exposure because of the proposed action. The environmental assessment and the finding of no significant impact was published on April 17, 2024 (89 FR 27465).

IV. Conclusion

Based on these considerations, the NRC has determined that, pursuant to 10 CFR 72.7, the exemption is authorized by law, will not endanger life or property or the common defense and security, and is otherwise in the public interest. Therefore, the NRC grants TVA an exemption from the requirements of §§ 72.212(a)(2), 72.212(b)(3), 72.212(b)(5)(i), 72.212(b)(11), and 72.214 with respect to the future loading in the HI-STORM FW MPC Storage System of five MPC-37-CBS beginning in July 2024.

This exemption is effective upon issuance.