Nuclear Regulatory Commission staff last week formally signed off on exemptions in operation of a spent fuel storage facility for the retired Vermont Yankee nuclear power plant.
The Feb. 2 safety evaluation report follows a Jan. 11 environmental assessment and finding of no significant impact by agency staff for those same exemptions requested by plant owner Entergy.
Those were the only reviews needed for Entergy to use the HI-STORM 100 dry storage casks, NRC spokesman Neil Sheehan said Tuesday.
“The staff concludes that the proposed actions … [do] not affect the ability of the HI-STORM 100 cask system to meet the requirements of 10 CFR Part 72,” the federal regulation covering licensing for storage of spent nuclear fuel, according to the staff safety report.
Last year, Entergy asked for authorization to use an “optional regionalized loading pattern” for the multipurpose canisters used in the HI-STORM 100 storage system from Holtec; load fuel cooled for no less than two years into the canister, rather than the generally required three-year cooling period; and ready a per-cell maximum average burnup limit of 65,000 megawatt days per metric ton of uranium.
Entergy “noted that the approval of the exemption request will facilitate a continuous loading campaign without interruption to wait for the fuel to meet the heat loading requirement for individual cell location,” the safety report says.
Staff also noted this could avoid potential higher personal exposure and human errors due to loss of experienced workers. Entergy indicated the exemptions would enable Vermont Yankee to complete the transfer of irradiated fuel by the end of 2018 instead of 2020, the report says.
Entergy closed Vermont Yankee in December 2014, and is moving all remaining used fuel into dry storage. The power company and Holtec International last year began the final spent fuel transfers to eventually fill 58 dry casks – a requirement for Entergy’s planned sale of Vermont Yankee to NorthStar Group Services for decommissioning.
