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{{#Wiki_filter: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
{{#Wiki_filter:UCS Perspectives on Accident-Tolerant Fuel


Is Accident-Tolerant Fuel False Advertising?
Dr. Edwin Lyman Director of Nuclear Power Safety Climate and Energy Program Union of Concerned Scientists
* 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
January24,2023 Is Accident-Tolerant Fuel False Advertising?
* Uncertainties and tradeoffs of ATF concepts relative to conventional fuels (even the near-term approaches) make it difficult to assess the overall safety benefits
* UCSstronglysupports efforts to develop fuels that would genuinely increase safety
  - FeCrAl cladding in particular
*Butthat no longer appears to be the main goal of the current accident-tolerant fuel (ATF) program
* NUREG/CR-7282/ERI-NRC/21-203, 2021:
*Becauseoftheeconomic link between ATF technologies, higher burnup, and increased enrichment
  - It is seen that there is conflicting information about the impact of doping on fission gas release behavior  
... NRC staff considers the pursuit of higher burnup and increased enrichment a component of theATFprogram
  - The available literature is much more complete with respect to ATF design characteristics than with the behavior of ATF under severe accident conditions.
-NRC ATF Licensing Project Plan, version 2.1 (2021)
  - 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
*Raisesthepossibility that higher-burnup risks will outweighthe safety margins (if any) that accident-tolerant features might provide 2
ATFuncertainties
* Uncertaintiesand tradeoffs of ATF concepts relative to conventional fuels (even the near-term approaches) make it difficult to assess theoverall safety benefits
-FeCrAl cladding in particular
*NUREG/CR-7282/ERI-NRC/21-203, 2021:
-It is seen that there is conflicting informationabouttheimpactof dopingonfission 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 EPRIalternate licensingstrategy to allow fuel fragmentation, relocation, and dispersal(FFRD) to be excluded from large-breakloss-of-coolant accident analysis
-The potentially serious safety implications of FFRD must befully assessedfor any HBU fuel proposal
*Safetyimpacts of increased enrichment also must be thoroughly evaluated
-Powerpeaking, 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


High-burnup/increased enrichment risks
4 And dont forget the spent fuel
* 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
*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
  - 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
5 Theneedfor50.46(c)
* 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
* 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
*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
*Swift approval of the 50.46(c) rule by NRC would go a long way towardclosingthisgap


Acronyms
6 Acronyms
* ATF: Accident-Tolerant Fuel
* ATF: Accident-Tolerant Fuel
* ERI: Energy Research, Inc.
*ERI:EnergyResearch,Inc.
* FeCrAl: Advanced Stainless Steel
*FeCrAl: Advanced Stainless Steel
* FFRD: Fuel Fragmentation, Relocation, and Dispersal
*FFRD: Fuel Fragmentation, Relocation, and Dispersal
* HBU: High Burnup
*HBU: High Burnup
* IE: Increased Enrichment
*IE: IncreasedEnrichment
* UCS: Union of Concerned Scientists 7}}
*UCS: Union of Concerned Scientists
 
7}}

Revision as of 11:37, 15 November 2024

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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Text

UCS Perspectives on Accident-Tolerant Fuel

Dr. Edwin Lyman Director of Nuclear Power Safety Climate and Energy Program Union of Concerned Scientists

January24,2023 Is Accident-Tolerant Fuel False Advertising?

  • UCSstronglysupports efforts to develop fuels that would genuinely increase safety
  • Butthat no longer appears to be the main goal of the current accident-tolerant fuel (ATF) program
  • Becauseoftheeconomic link between ATF technologies, higher burnup, and increased enrichment

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

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

  • Raisesthepossibility that higher-burnup risks will outweighthe safety margins (if any) that accident-tolerant features might provide 2

ATFuncertainties

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

-FeCrAl cladding in particular

  • NUREG/CR-7282/ERI-NRC/21-203, 2021:

-It is seen that there is conflicting informationabouttheimpactof dopingonfission 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 EPRIalternate licensingstrategy to allow fuel fragmentation, relocation, and dispersal(FFRD) to be excluded from large-breakloss-of-coolant accident analysis

-The potentially serious safety implications of FFRD must befully assessedfor any HBU fuel proposal

  • Safetyimpacts of increased enrichment also must be thoroughly evaluated

-Powerpeaking, 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 Theneedfor50.46(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 towardclosingthisgap

6 Acronyms

  • ATF: Accident-Tolerant Fuel
  • ERI:EnergyResearch,Inc.
  • FeCrAl: Advanced Stainless Steel
  • FFRD: Fuel Fragmentation, Relocation, and Dispersal
  • HBU: High Burnup
  • IE: IncreasedEnrichment

7

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