ML23018A054

M230124: Slides/Supporting Presentation Material - E. Lyman - Overview of Accident Tolerant Fuel Activities

ML23018A054
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Issue date:	01/24/2023
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UCS Perspectives on Accident-Tolerant Fuel Dr. Edwin Lyman Director of Nuclear Power Safety Climate and Energy Program Union of Concerned Scientists January 24, 2023

Is Accident-Tolerant Fuel False Advertising?

• UCS strongly supports efforts to develop fuels that would genuinely increase safety

• But that no longer appears to be the main goal of the current accident-tolerant fuel (ATF) program

• Because of the economic link between ATF technologies, higher burnup, and increased enrichment

... NRC staff considers the pursuit of higher burnup and increased enrichment a component of the ATF program

- NRC ATF Licensing Project Plan, version 2.1 (2021)

• Raises the possibility that higher-burnup risks will outweigh the safety margins (if any) that accident-tolerant features might provide 2

ATF uncertainties

• Uncertainties and tradeoffs of ATF concepts relative to conventional fuels (even the near-term approaches) make it difficult to assess the overall safety benefits

- FeCrAl cladding in particular

• NUREG/CR-7282/ERI-NRC/21-203, 2021:

- It is seen that there is conflicting information about the impact of doping on fission gas release behavior

- The available literature is much more complete with respect to ATF design characteristics than with the behavior of ATF under severe accident conditions.

- Within considerable variation, [ATF-related severe accident simulations] tend to confirm a widely held impression that ATF designs typically afford a modest increase in coping time and a reduction of hydrogen generation, at least until very late times. 3

High-burnup/increased enrichment risks

• UCS is concerned about the EPRI alternate licensing strategy to allow fuel fragmentation, relocation, and dispersal (FFRD) to be excluded from large-break loss-of-coolant accident analysis

- The potentially serious safety implications of FFRD must be fully assessed for any HBU fuel proposal

• Safety impacts of increased enrichment also must be thoroughly evaluated

- Power peaking, lower control rod worth, recriticality

• 2021 NRC-led Phenomena Identification and Ranking Tables severe accident study examined ATF concepts and high-burnup/increased enrichment (HBU/IE) with conventional fuel/cladding, but did not consider ATF and HBU/IE together, even though that is the most likely batch loading that licensees will pursue 4

And dont forget the spent fuel

• Potentially deleterious impacts of alternative cladding materials and HBU/IE on spent fuel management and disposal should be fully assessed before batch loading is approved 5

The need for 50.46(c)

• The proprietary nature of much fuel design and performance data limits opportunities for public understanding of the basis for regulatory decisions and diminishes public confidence

• This is exacerbated by the absence of clear and consistent regulatory requirements for approving the safety of new fuel types

• Swift approval of the 50.46(c) rule by NRC would go a long way toward closing this gap 6

Acronyms

• ATF: Accident-Tolerant Fuel

• ERI: Energy Research, Inc.

• FeCrAl: Advanced Stainless Steel

• FFRD: Fuel Fragmentation, Relocation, and Dispersal

• HBU: High Burnup

• IE: Increased Enrichment

• UCS: Union of Concerned Scientists 7