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Slides (External) - IE Rulemaking Industry Feedback - Sc - January 16, 2025
	ML25014A192
Person / Time
Site:	Nuclear Energy Institute
Issue date:	01/14/2025
From:	Andersen V, Barber K, Chavers J, Paul Clifford, Csontos A, Matheny T, Mount B, Sarikaya B, Stavely J; BWR Owners Group, Constellation Energy Generation, Dominion, Duke Energy Corp, Framatome, Nuclear Energy Institute, Public Service Enterprise Group, PWR Owners Group, Southern Co, Westinghouse
To:	; Advisory Committee on Reactor Safeguards
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	Download: ML25014A192 (31)
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©2025 Nuclear Energy Institute Al Csontos - NEI Victoria Anderson - NEI Jim Stavely - PSEG Tara Matheny - Duke Jonathan Chavers - Southern Baris Sarikaya - Constellation/BWROG Brian Mount - Dominion/PWROG Kevin Barber - Westinghouse Paul Clifford - Framatome IE Rulemaking:

Industry Feedback January 16, 2025

©2025 Nuclear Energy Institute 2 LARs for uprates and/or advanced fuels are on the way IE rule and schedule are vital to industry strategic plans Draft IE Rule from the recent ACRS meetings has many appropriate improvements, but major concerns remain Industry feedback remains consistent with March 23 letter:

Combined/modernized rule with modified 50.46a/c (ML23107A230)

ACRS should allow the draft IE rule for Commission review Workshops needed for industry engagement on concerns IE Rulemaking Key Messages ADVANCE Act alignment for modern, risk-informed, and efficient regulations

Generally, beneficial impacts with the overall rule package:

Enables improved safety benefits associated with less generated waste

Allows increase enrichments to LEU+

Allows existing UF6 packages to ship with up to 10 wt% U-235

Improved risk-informed control room dose design criteria

RG 1.183 revisions permit some units to move forward with strategic plans

More realistic modeling of potential release paths

NRC workshops yielded a more predictable, durable, and stable RG

Openness to LBLOCA as BDBA has potential for significant improvements

NUREG-2266 for up to 10 wt% U-235 and 80 GWd/MTU burnup Specific areas remain deterministic, prescriptive, and not risk-informed with additional burdens and high uncertainty to implementation IE Rulemaking Key Messages

©2025 Nuclear Energy Institute 4 Enabling Advanced Fuel Technologies SAFELY SUSTAIN THE FLEET Enhanced Fuel Performance Enhanced Fuel Reliability Improved Operational Flexibility Fuel Cycle Optimization Accelerate ATF Fuel Transition 20% Less Waste &

$3.5 Billion Savings

$9.4 Billion in Industry Fuel Savings 24 Month Refueling Cycles ATF/LEU+/HBU fuels are complementary to uprates and enabling in some cases Modern advanced fuel technologies can:

Increase potential for power uprates

Enable 24-month fuel cycles for PWRs

Less waste = improved safety/fuel efficiency

Improve plant resiliency and performance

Improve economics for fleet sustainment On track to meet industrys goal to deploy batch quantities in the mid-to-late 20s:

Applications for 24-month cycles submitted

Efficient NRC licensing for advanced fuels and uprates by 2027 with the IE rule needed

>70% of sites have a level of interest/planning for one or more power uprates with a combined capacity increase of 3 GWe

Nearly 50% of sites have varying interest/plans for one or more of the enabling changes (ATF/

LEU+, Extended Fuel Cycles, and/or RI LOCA) https://www.nei.org/resources/reports-briefs/the-future-of-nuclear-power-2024-survey 2024 NEI Future of Nuclear Power Survey

LOCA Risk Significance IMPACT OF LOCA ON OVERALL PLANT RISK

Review of Industry Baseline Risk Index for Initiating Events (BRIIE) - NUREG/CR-6932 for Initiating Events leading to core damage (1988-2005):

VSLOCAs have CDFs on the order of 1E-10 (BWRs) and 1E-09 (PWRs) yr-1 Small sample of plants confirm. MLOCAs slightly higher but on the order of E-7 to E-8 (PWR, BWRs) yr-1 for CDF LERF values ~ 2-3 orders of magnitude smaller than CDF E-9 to E-11 yr-1 for LERF Compared to mean CDFs of 1E-05 and 1E-06 yr-1 OE Extended to 2020 in INL/EXT-21-63577 Plant risk and safety performance have continued to improve (utilities focusing on maintenance and improvements that positively impact risk, safety, and operability)

Figures on right show plant risk reduced by a factor of 20 (NEI-20-04-The-Nexus-Between-Safety and Operational Performance)

LOCAs not Significant Contributors to Overall Plant Risk

Early Industry Draft IE Rule Feedback AREAS FOR IMPROVEMENT

2010 Draft 50.46a rule required substantial implementation burden as compared to the potential benefits utilities would obtain (see ML100260383 & ML10316027)

Risk Informed Evaluation Process (RIEP): New rule does not appear to implement efficiencies and learnings associated with risk informed change programs that most of the fleet has implemented since 2010.

More stringent criteria for what requires NRC approval compared to what most of the fleet is approved to use today Draft rule still stipulates the performance of low power shutdown (LPSD) risk assessments/PRAs (NEI 2023 Att. 1, Item 1) even though the industry addressed this after 2010 50.46a (h) RIEP duplicates requirements for implementing risk informed change programs communicated in RG-1.200 and RG-1.174

Existing NRC-approved robust aging management program (submitted as a part of plant license renewals) protects against degradation of primary loop piping (PLP)

DG-1428 acknowledges the industry addressed seismic risk per NRC 10CFR50.54 order after Fukushima-Daiichi event but still requires plant specific seismic analyses. (NEI 2023 Att.1, Item 2)

DG-1428 imposes additional in-service inspection (ISI) requirements per 50.46 a(b)(3) even though the frequency of rupture is decreasing resulting from maturity increases in PFM These increased inspections would result in unnecessary additional occupational dose to plant personnel and is not risk-informed.

DG-1428 extension of credit for plants with approved LBB programs is minimal (NEI 2023 Att.1, Item 4)

Additional Implementation Considerations New analyses for 50.46 compliance > TBS New dose analyses for LOCA with FFRD DG-1428 requires the performance of plant specific pipe and component stress evaluations in addition to increased inspection frequencies Draft rule requires new Technical Specifications for non-safety equipment credited in > TBS ECCS compliance analysis (which is beyond design basis) and is inconsistent with Industrys treatment of FLEX equipment Ongoing Activities NRC supporting work to evaluate continued use of TID source term for EQ; The outcome of this could have significant impacts on implementation

Draft rule does not allow alternative approaches

Codifying a prescriptive TBS definition may lead to future rulemaking and/or exemption requests NRC has communicated desire to allow alternative paths With minimal changes in rule language, a more flexible and durable rule capable of supporting advancements in risk-informed applications is achievable Flexible and Durable

©2025 Nuclear Energy Institute 14 Rule should be structured to allow alternative approaches to defining and implementing TBS Regulation should allow a TBS demarcation which separates beyond design basis based on risk-insights Current TBS definition (50.46a(a)(9)) and SOC bases should be moved to regulatory guidance (i.e., DG-1428)

Analytical requirements in 50.46a(e) need to be flexible enough to allow alternative approaches and where possible moved to regulatory guidance These changes enable near-term alternative approaches without the need for exemption requests EPRI ALS, true risk-informed metrics (CDF), break frequency, etc.

Flexible and Durable

Downstream consequences of dispersed fuel, including coolability, are removed from the design basis of ECCS performance

Plants must demonstrate compliance to well within 10 CFR 50.67 dose limits (i.e., 6.3 rem TEDE)

Must consider additional source term associated with dispersed fuel

Applies to all break sizes and reactor types DG-1425 includes guidance for demonstrating compliance with Alternative #4 Draft §50.46 rule does not include an alternative path to enable implementation of Alternative #4 Discrepancy needs to be resolved Flexible and Incorporation of Alternative #4

Industry Advancements Since 2005, fleet has implemented approved risk-informed licensing applications and change processes Lower probability of initiating event identified during reconfirmation of NUREG-1829/NUREG-1903, but Draft RGs require increased inspections Implementation and inspections should capitalize on currently available information

Industry Standards Effect on risk due to changes at sites are assessed based on RG-1.174

>TBS beyond design basis, but reporting requirements increased compared to current design basis LOCA Breakaway oxidation testing requirement does not recognize fuel vendor quality assurance, manufacturing control, and design change procedures Requirements should account for current industry standards, not increase inspection & reporting requirements for beyond design basis events

Cladding Embrittlement DG-1263, Rev. 1 does not account for NRC-approved cladding alloys that considered known embrittlement mechanisms Licensed alloys that considered known embrittlement mechanisms should not require additional licensing actions

Without justification, draft§50.46 and§50.46a extend the long-standing definition of LOCA beyond breaks in piping (original bases* shown below)

The wording of the definition of a loss-of-coolant accident has been modified to conform to its long-accepted usage, limiting it to breaks in pipes.

Extending the definition of LOCA beyond its historical scope has significant consequences to both the existing fleet and future advanced LWRs

This change would invalidate the design basis of current fleet

The change to the existing § 50.46 definition is not included in the backfitting determination and would render the rule mandatory

Definition should be restored to its long-accepted usage for 40 years

Original bases in 39 FR 1002, January 4, 1974

Because its a voluntary alternative, NRCs Backfit assessment states that licensees would not be required to comply with the proposed amendments and would have the option to continue their current treatment of LOCAs

Industry agrees with NRCs earlier assessments that LOCA fuel dispersal at current BU limits and § 50.46c research findings are not safety significant

NRC MD 8.4 states that if a backfit has not been imposed for cases where a forward fit is being considered, it is unlikely that a change could be justified to be necessary to ensure adequate protection of public health and safety

Based on the above, industry expects that future LARs and vendor topical reports which comply with § 50.46 will not to be subjected to new requirements (i.e., continue current treatment of LOCAs)

Forward-fitting via vendor topicals should not be allowed

Relaxing assumptions generally provides analytical benefits, but interpretation of BDB LOCA requirements can greatly impact fuel dispersal conclusion NRC expects that with true best-estimate modeling and realistic assumptions, the quantity of fuel calculated to be dispersed would be eliminated or greatly reduced. (Draft FRN)

BDBA analyses are used to fully understand the capability of the plant design, rather than establishing tech specs and operational limits based on fuel performance BDBA conclusions should not be obscured by artificial biasing Analyses should consider as-expected conditions Conservatism may be included as a matter of convenience, but is not required Characteristics of true best-estimate for BDB LOCA Nominal operating values shall be applied (e.g., operational target, midpoint of a range)

Break considerations should reflect physical plant geometry (e.g., relative frequencies)

Mitigating systems are available and functional (e.g., non-safety, no single failure, offsite power, etc.)

Code models should be best-estimate and applied without bias

©2025 Nuclear Energy Institute 21 IE rule with 50.46a/c would enable more realistic operational margins for advanced fuels and additional power uprates as incentivized in the IRA Alignment of the combined draft rule to Commission direction and intent of the ADVANCE Act for a modern, risk-informed, and efficient regulatory process Industry feedback remains consistent with recent NEI letters:

Combined/modernized rule with modified 50.46a/c - Mar 23 (ML23107A230)

IE Rulemaking Regulatory Basis industry comments - Jan 24 (ML24023A604)

Development of a clear, efficient, and durable rule with draft regulatory guides needs full consideration of the holistic implementation pathway for licensees NRC workshops would enable an open and transparent dialogue on the Industrys implementation, efficiency, predictability, and durability concerns Summary

Backup

©2025 Nuclear Energy Institute 23 Assumed operating conditions at time of break reflect most likely state of the plant Nominal values or midpoint of ranges without uncertainty Nominal peaking factors and axial power condition Nominal or as-coded models without conservative uncertainties or biases Realistic accident conditions consider all relevant systems Breaks and distribution of sizes can account for physical plant geometry and expected frequencies of occurrence No single failure or loss-of-offsite power Non-safety systems can be credited True Best Estimate Conditions assumed for beyond design-basis accident analysis should not be tied to technical specification limitations

©2025 Nuclear Energy Institute 24 True risk-informed approach consistent with approved risk-informed programs already existing in plants license bases TBS should be defined based on plant-specific risk profile (e.g. 10-7 CDF)

Above TBS, PRA models must continuously demonstrate that plant-specific risk remains below TBS threshold

Full LOCA break spectrum included in internal events scenarios

More detailed analytical demonstration not needed for insignificant risk At or below TBS, traditional LOCA EMs used for compliance demonstration Future changes in plant configuration, operating conditions, and technical specifications assessed to confirm TBS and overall plant risk Optimized Risk-Informed Approach

©2025 Nuclear Energy Institute 25 Modified Alternative 4 Universally applicable to BWR and PWR fleet Building upon proven risk-informed regulatory process Demonstrated no fuel dispersal Avoids complex, downstream consequence analyses Removes reporting requirements Benefits of Optimized Risk-Informed Approach

©2025 Nuclear Energy Institute 26 Considerations/Clarifications for Modernized 50.46a Rule Consideration/Clarification Justification LOCAs > transition break size (TBS) would be treated as beyond design basis with realistic assumptions. NRC approved thermal-hydraulics method may not be needed for large breaks.

> TBS = Beyond Design Basis is consistent with intent of 50.46a (SECY-10-0161)

Considerations based on information in Reactor Accident Analysis Modernization Report: Item 2.4 (ML24220A292)

Use of Chapter 19 methods could be acceptable (Section 2.4.1)?

Demonstrate compliance with RG-1.200 acceptance criteria (including DiD), and NRC review and approval may not be required?

LOCAs < TBS (design basis) could take credit for RI single failure, some non-safety SSCs, and use alternate criteria to demonstrate high probability?

LOCAs are not significant contributors to plant risk and ECCS performance is not credited to satisfy dose acceptance criteria?

Based on industry interpretation of RAAM Items 2,2, 2.3, 2.6 Selection of TBS could be based on risk criteria (CDF, LERF)?

Draft 50.46a rule used initiation event frequency which is not a true risk metric (omits consequences)?

Separate approval of some changes under 50.46a may not be required?

Utilities that have received approval for other RI programs would receive credit for QA of RI change programs?

Evaluation of changes under RG-1.174 for RI programs and 50.59 are well vetted and established.

Site specific seismic risk demonstrations under NUREG-1903 would not be required?

Utilities have addressed plant specific seismic risk as a part of Post-Fukushima Task Force requirements/recommendations Implementation of a modernized 50.46a would be voluntary?

Consistent with 2010 draft 50.46a rule

& ML10316027)

Risk Informed Evaluation Process: New rule does not appear to implement efficiencies and learnings associated with risk informed change programs that the majority of the fleet has implemented since 2010

Specifies use of Region III CDF (1.0 E-07) and LERF (1E-08) criteria in RG-1.174 to determine if a change is acceptable

Requires any change processed under 50.46a to be approved by NRC if the change falls outside of Region III

Whereas other approved risk informed programs use a Region II criteria

ACRS in response to Issue 3 (ML070460275) recommended Region II criteria

[CDF (1.0 E-06) and LERF (1E-07)] for changes and that any changes that increase risk > Region II criteria should require staff review

©2025 Nuclear Energy Institute 28 Implementation Burden Justification for applicability of the transition break size (TBS) contained in DG-1428 requires more reactor coolant piping weld inspections (NUREG-1829) and plant specific seismic evaluations (NUREG-1903)

DG-1428 (Section B.2) acknowledges the industry addressed seismic risk per NRC 10CFR50.54 order after Fukushima-Daiichi event.

DG-1428 (B.1.3) imposes additional in-service inspection (ISI) requirements per 50.46 a(b)(3) even though presentations to ACRS on 12/17/24 demonstrate that the frequency of rupture is decreasing resulting from maturity increases in PFM. These increased inspections would result in unnecessary additional dose to plant personnel.

Implementation of the draft rule would also require new analyses:

DG-1425 requires a new dose analysis LOCA with FFRD with an acceptance criteria 25%

of MHA LOCA even though DG-1425 acknowledges MHA LOCA bounds LOCA with FFRD.

LOCA with FFRD is valid under Alternative 4 50.46a rule requires a new true best-estimate LOCA analysis for breaks > TBS, still requires deterministic LOCA analysis that must be maintained by the Licensee, in addition to the current LOCA analyses for breaks TBS Draft rule still requires compliance to 50.46 design basis acceptance criteria for both analyses even though it is recognized > TBS is beyond design basis DG-1428 requires the performance of plant specific pipe and component stress evaluations along with ISI inspection information that needs to be approved by the NRC to use a TBS DG-1428 requires the performance of a plant specific seismic evaluation for pipe and components that could fail and impact pipe pressure boundary performance, while acknowledging plants have already addressed seismic risk New TS (Never could find in what document the new TS is required

©2025 Nuclear Energy Institute 30 The draft rule does not reflect the significant advancements in licensing actions, including risk-informed applications, since the draft § 50.46a rule was first developed in 2005 Applicability of § 50.46 and DG-1263 should be expanded to include all approved cladding alloys Demonstration of acceptable performance already justified Since 2005, fleet has implemented approved risk-informed licensing applications and change processes Duplicative RIEP codified in draft § 50.46a unnecessary Unjustified differences from approved risk-informed applications Modernization

©2025 Nuclear Energy Institute 31 Draft § 50.46 and § 50.46a maintain legacy reporting requirements In 1974, computational limitations and uncertainties necessitated reporting to provide book-keeping and NRC confidence Unrelated to plant safety Given the anticipated large margins to acceptance criteria, At or Below TBS reporting should only be required when predictions approach criteria.

No reporting requirements should be required for Above TBS BDBAs Best-estimate, realistic calculations are not deterministically bounding, therefore book-keeping is unnecessary Licensees required to take corrective actions to ensure compliance This legacy reporting requirement should be removed Modernization

ML25014A192

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