The US Nuclear Regulatory Commission (NRC) has decided to discontinue its considerations of regulatory and other changes which would allow NPP operators to apply for 40-year licence renewals — conceivably extending some operating lives to 100 years. It recommended further evaluations to address the potential for reactor operations up to 100 years.
NRC said via Facebook: "Our process for reviewing requests to extend reactor operating licences uses 20-year renewal periods. Over the past few years, almost every operating US nuclear power plant has applied for and received 20-year extensions after meeting our rigorous safety standards. We've been considering whether to allow nuclear power plant owners to request 40-year renewals, and we held a public meeting on the topic earlier this year. After fully considering the options and public input, we've ended the 40-year renewal discussion, and we've also offered recommendations on enhancing renewal-related inspections and oversight."
NRC’s decision is outlined in a memorandum dated 22 June. It noted that NRC had been considering the issue since May 2020.
“With more than 90 percent of the operating reactors possessing renewed licences for operation to 60 years, this activity included consideration of the technical issues that would be associated with plant operation to 100 years.”
It added: “Since the current licence renewal guidance documents address plant operation to 80, the adequacy of these documents to support 100 years of SSC operation, or the need for separate documents for 100 years of operation, has not been assessed.”
NRC made the following five recommendations:
- Discontinue the activity to consider regulatory and other changes to enable licence renewal for 40 years.
- Consider an evaluation of possible changes to oversight and inspection activities related to license renewal and subsequent licence renewal.
- Consider an evaluation to identify on-going research activities (related to concrete, cables, reactor vessel internals and reactor pressure vessels) that could be extended to greater exposure levels (e.g., higher fluence levels) to address the potential for reactor operations up to 100 years.
- Periodically query the industry to determine their interest and timing to pursue operation to 100 years, so that the staff can identify the need and timeframe to initiate development of guidance documents which would support 100 years of plant operation.
- Consider an evaluation of impacts to plant risk from the combined effects of multiple aged components, and affirmation of the conclusions in NUREG-1412, “Foundation for the Adequacy of the Licensing Bases, A Supplement to the Statement of Considerations for the Rule on Nuclear Power Plant Licence Renewal (10 CFR Part 54),” should licence renewal to 100 years of plant operation be contemplated in the future.
NRC noted that six reactor units already had renewed licences for operation to 80 years, and these could ultimately seek licences to operate for 100 years, potentially beginning in 2029. The working group, which considered these issues “was divided on whether to take a position on initiating development of guidance documents for 100 years,” NRC said. “However, a consensus was reached to proposeinvestigating research opportunities to extend the exposure levels for the major ageing management issues”, which had been identified in an earlier staff requirements memorandum in 2014. The issues identified included reactor pressure vessel neutron embrittlement at high fluence, irradiation-assisted stress corrosion cracking of reactor internals and primary system components, concrete and containment degradation, and electrical cable qualification and condition assessment.
With on-going NRC research in these areas (cracking of reactor internals, concrete and containment degradation, and electrical cable qualification and condition assessment), the working group “recommends consideration of efficiency and effectiveness of extending this on-going research to increase the exposure levels to address expected conditions for 100 years of operation.”
In addition to this on-going research, the continued efforts to explore and pursue opportunities to harvest materials and components from decommissioned plants also can be used to provide insights and data on materials ageing at high exposure levels. “The staff assesses harvesting opportunities as they arise to determine whether the data on materials ageing will be useful/beneficial for supporting long term operation."
Photo: Surry was recently licensed to operate until the 2052/2053 (Credit: Dominion Energy)