ML18247A321

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Presentation Slides: Dry Storage and Transportation of High Burnup Spent Nuclear Fuel: Draft Report for Comment
ML18247A321
Person / Time
Issue date: 09/06/2018
From: Wendy Reed
Renewals and Materials Branch
To:
Reed W
References
Download: ML18247A321 (22)
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NUREG-2224 Dry Storage and Transportation of High Burnup Spent Nuclear Fuel Draft Report for Comment September 6, 2018 U.S. NRC, Rockville, MD

NUREG-2224 Draft Report for Comment ADAMS Accession No.: ML18214A132 Public comment period ends September 24 o Comment via website: http://www.regulations.gov, Docket ID: NRC-2018-0066 o Mail comments to:

May Ma Office of Administration, Mail Stop: TWFN-7-A60M U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 o Questions about material in NUREG-2224:

Wendy.Reed@nrc.gov September 6, 2018 NUREG-2224 Public Meeting 2

Safety Review Objectives Spent Fuel Assemblies Heat Removal Subcriticality Controlled fuel temperature Unsustainable and internal stresses fission reaction Structural Performance Maintain analyzed configuration Ready retrieval Radiation Shielding Confinement / Containment On-site worker and public No release of radioactive dose limits material September 6, 2018 NUREG-2224 Public Meeting 3

Spent Fuel Assembly Review Guidance Framework Initial Licensing / Certification Standard Review Plans Interim Staff Guidance Dry Storage: ISG-1, Rev. 2 (2007)

NUREG-2215 (2018) ISG-2, Rev. 2 (2016)

ISG-11, Rev. 3 (2003)

Transport: ISG-19 (2003), ISG-22 (2006)

NUREG-1617 (2000) ISG-24 (initial/ renewal, 2014)

Renewal (Dry Storage)

Standard Review Plans Technical Report NUREG-1927, Rev. 1 (2016) NUREG-2214 (2018)

September 6, 2018 NUREG-2224 Public Meeting 4

ISG-11, Rev. 3 Cladding Considerations

  • Defines SNF cladding temperature limits that provide reasonable assurance that creep and hydride reorientation will not compromise SNF cladding integrity during transportation and dry storage
  • Research conducted since issuance of ISG-11, Rev. 3, suggested that hydride reorientation could not be prevented in HBU SNF cladding
  • Since then, both NRC and DOE have conducted extensive testing to understand the effects of hydride reorientation on the mechanical performance of HBU SNF September 6, 2018 NUREG-2224 Public Meeting 5

Hydride Reorientation

  • What is it?

- Hydrogen in the cladding dissolves during drying/short-term loading operations

- As the fuel cools down, hydrides precipitate in a different orientation

  • Why has it been a concern?

- Impact to cladding mechanical properties

- Fuel performance under bending and pinch-type loads

  • How has NRC addressed it?

- Separate-effects testing (NUREG/CR-7198)

- Draft Regulatory Information Summary (2015)

- NUREG-2224 (2018)

September 6, 2018 NUREG-2224 Public Meeting 6

Purpose of NUREG-2224

  • Updates NRC staffs technical basis on HBU SNF cladding performance

- Provides an engineering assessment of results on mechanical performance of HBU SNF following cladding hydride reorientation

  • Efficiency in the preparation and review of storage renewal applications

- Provide example licensing/certification approaches for dry storage and transportation of HBU SNF September 6, 2018 NUREG-2224 Public Meeting 7

Contents of NUREG-2224 Front Matter

1. Introduction
2. Assessment of Static Bending and Fatigue Strength Results on HBU SNF (per NUREG/CR-7198, Rev. 1)
3. Dry Storage of HBU SNF (licensing/certification)
4. Transportation of HBU SNF (certification)
5. Conclusions
6. Glossary
7. References September 6, 2018 NUREG-2224 Public Meeting 8

Introduction

  • Background / Regulatory requirements
  • Cladding creep
  • Hydride reorientation

- Dissolution / Precipitation

- Fuel cladding fabrication effects

- End-of-life rod internal pressures / Cladding hoop stresses

- Ring compression testing (RCT)

- Staffs assessment of RCT results September 6, 2018 NUREG-2224 Public Meeting 9

Assessment of Static Bending /

Fatigue Strength Results

  • Introduction / CIRFT background
  • Application of static test results

- Spent fuel rod behavior in bending

- Composite behavior of spent fuel rod

- Calculation of cladding strains

- Applicability to dry storage and transportation

  • Application of fatigue test results

- Lower bound fatigue S-N (strain vs no. cycles) curves

- Fatigue cumulative damage model

- Applicability to dry storage and transportation September 6, 2018 NUREG-2224 Public Meeting 10

Assessment Conclusions Static Bending (Zircaloy-4)

  • CIRFT results for HBU SNF rod specimens confirmed that hydride reorientation does not impact the fuels flexural rigidity for expected bending moments due to drop accidents
  • Hydride-reoriented HBU SNF rod specimens showed markedly higher bending moment resistance compared to the calculated cladding-only response

- Confirmed that use of cladding-only mechanical properties is adequate for the evaluation of drop accidents (all cladding types)

  • Proposed new approach for crediting flexural rigidity of the pellet in the drop accident safety analyses (all cladding types)

September 6, 2018 NUREG-2224 Public Meeting 11

Assessment Conclusions Fatigue Endurance (Zircaloy-4)

  • Hydride-reoriented HBU SNF rod specimens failed at similar equivalent strains than non-reoriented HBU SNF rod specimens
  • Lower-bound fatigue S-N curve developed per NUREG/CR-7198, Rev. 1 results

- Approach can be replicated with CIRFT dynamic test data obtained for other HBU SNF cladding types

- DOE to acquire additional HBU SNF materials performance data (CIRFT dynamic/static, uniaxial tensile/pressure burst testing/4 point bend testing) under their ongoing Sister Rod Program September 6, 2018 NUREG-2224 Public Meeting 12

Assessment Conclusions Licensing and Certification

  • Developed example licensing and certification approaches based on the assessment conclusions per NUREG/CR-7198, Rev. 1 results (see Tables 3-1 and 4-1, NUREG-2224)

- Ensured consistency with new consolidated SRPs for dry storage and transportation, and Managing Aging Processes in Storage Report (NUREG-2214)

- Approaches vary depending on the condition of the fuel (undamaged vs. damaged) and length of time in dry storage

  • Applicants may propose and demonstrate alternative approaches to be acceptable September 6, 2018 NUREG-2224 Public Meeting 13

Dry Storage of HBU SNF Licensing and Certification

  • Introduction
  • Uncanned fuel (intact and undamaged fuel)

- Leaktight confinement

- Non-leaktight confinement (HBU SNF release fractions)

- Dry storage up to 20 years

- Dry storage beyond 20 years

  • Results from confirmatory demonstration (NUREG-1927, Rev. 1)
  • Canned fuel (damaged fuel)

September 6, 2018 NUREG-2224 Public Meeting 14

Transportation of HBU SNF Certification

  • Introduction
  • Uncanned fuel (intact and undamaged fuel)

- Leaktight containment

- Non-leaktight containment (HBU SNF release fractions)

- Shipment of directly-loaded fuel / previously dry-stored fuel (up to 20 years)

- Shipment of previously dry-stored fuel (beyond 20 years)

  • Results from confirmatory demonstration (NUREG-1927, Rev. 1)
  • Canned fuel (damaged fuel)

September 6, 2018 NUREG-2224 Public Meeting 15

Conclusions

  • NRC has assessed results on mechanical testing of hydride-reoriented HBU SNF rod specimens and confirmed that current approaches for evaluating drop accidents are conservative
  • NRC expects that additional data obtained under complementary research programs will provide additional confirmation and needed results to assess vibration normally incident to transport
  • NUREG-2224 improves the existing technical basis supporting the staffs conclusion that radial hydride reorientation will not compromise HBU SNF cladding integrity during transportation and dry storage up to 60 years September 6, 2018 NUREG-2224 Public Meeting 16

Questions in Federal Register Notice

  • Are NRCs assumptions regarding the performance of other cladding alloys based on data obtained from HBU SNF with Zircaloy-4 cladding for evaluating design basis drop accidents reasonable? If not, please explain why not.
  • Are the described licensing and certification approaches easy to follow and practical? If not, please explain why not.
  • Is the proposed approach for evaluation of vibration normally incident to transport clear? If not, please explain why not.
  • Are the discussions on consequence analyses due to hypothetical fuel reconfiguration clear and meaningful? If not, please explain why not.

September 6, 2018 NUREG-2224 Public Meeting 17

Questions in Federal Register Notice

  • Are there any potential conflicts between NUREG-2215, Standard Review Plan for Spent Fuel Dry Storage Systems and Facilities, Draft for Comment (ADAMS Accession No. ML17310A693) and this document? If so, please describe any conflicts.
  • Is the NRCs reassessment of the ductility transition temperature as measured by ring compression testing of defueled HBU SNF specimens reasonable? If not, please explain why not.

September 6, 2018 NUREG-2224 Public Meeting 18

Next Steps

  • Evaluate comments: Fall/Winter 2018
  • ACRS public meeting: Winter 2018/Spring 2019
  • Publish final report and document comment resolution:

Spring/Summer 2019 September 6, 2018 NUREG-2224 Public Meeting 19

Abbreviations

  • ADAMS - Agencywide Documents Access and Management System
  • CIRFT: Cyclic Integrated Reversible-Bending Fatigue Tester
  • DOE: Department of Energy
  • HBU: high burnup
  • ISG: interim staff guidance
  • No.: number
  • NRC: Nuclear Regulatory Commission
  • RCT: ring compression testing
  • Rev.: revision
  • SNF: spent nuclear fuel
  • SRP: Standard Review Plan September 6, 2018 NUREG-2224 Public Meeting 20

References

  • 10 CFR Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High Level Radioactive Waste, and Reactor-Related Greater than Class C Waste, Washington, DC.
  • NRC, A Quantitative Impact Assessment of Hypothetical Spent Fuel Reconfiguration in Spent Fuel Storage Casks and Transportation Packages. NUREG/CR-7203, Washington, DC, 2015, ADAMS Accession No. ML15266A413.
  • NRC, Cladding Considerations for the Transportation and Storage of Spent Fuel, ISG-11, Rev. 3, Washington, DC, 2003, ADAMS Accession No. ML033230335.
  • NRC, Classifying the Condition of Spent Nuclear Fuel for Interim Storage and Transportation Based on Function, ISG-1, Rev. 2, Washington, DC, 2016, ADAMS Accession No. ML071420268.

September 6, 2018 NUREG-2224 Public Meeting 21

References

  • NRC, Standard Review Plan for Renewal of Specific Licenses and Certificates of Compliance for Dry Storage of Spent Nuclear Fuel, NUREG-1927, Revision 1, Washington, DC, 2016, ADAMS Accession No. ML16179A148.

September 6, 2018 NUREG-2224 Public Meeting 22

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