ML18338A068

Presentation Slides: Status of Spent Fuel Cladding Tests

ML18338A068
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Issue date:	12/04/2018
From:	Meraj Rahimi Renewals and Materials Branch
To:
Lindsay H
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Progress Report on Spent Fuel Cladding Integrity Tests Meraj Rahimi Chief of Renewals and Materials Branch Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission

Spent Fuel Cladding Performance Safety Functions Subcriticality Unsustainable fission reaction Radiation Shielding Confinement / Containment On-site worker and public dose limits No release of radioactive material Structural Performance Maintain analyzed configuration (no operational problems with respect to spent fuel removal)

Heat Removal Fuel temperature Cladding stresses December 11, 2018 DSFM REG CON 2018 2

Spent Fuel Cladding Performance Review Guidance Framework Fuel temperature Cladding stresses ISG-11, Revision 3 Cladding Considerations (Peak Cladding Temperature / Thermal Cycling)

Dry Storage / Transport NUREG-2215 NUREG-2216 Standard Review Plan Standard Review Plan Dry Storage Transportation NUREG-2214 NUREG-2224 Managing Aging Processes Dry Storage / Transportation in Storage High Burnup Fuel December 11, 2018 DSFM REG CON 2018 3

Spent Fuel Cladding Performance Technical Bases / Position Considerations Performance-Related Phenomena ISG-11, Rev. 3, MAPS Report ISG-11, Rev. 3

• Hydride reorientation

1. Peak cladding temperature /

• Delayed hydride cracking Controlled hoop stresses

• Thermal creep 400 °C (758 °F) / 90 MPa

• Low-temperature creep

• Mechanical overload

2. Limited thermal cycling

• Oxidation SRPs / MAPS Report

• Pitting corrosion

• Galvanic corrosion

3. Inert environment

• SCC

4. Limited residual water

• Radiation embrittlement

• Fatigue

• None of these mechanisms are expected to compromise cladding integrity during transportation and dry storage up to 60 years.

• Data expected to confirm conclusions for dry storage beyond 20 years.

December 11, 2018 DSFM REG CON 2018 4

Where to next?

• What have we learned?

- Better understanding of hydride reorientation

• Additional confirmatory testing under DOEs Sister Rod Program

- Better understanding of rod internal pressures / gas communication

- Improved benchmarking of thermal models

• Revisit peak cladding temperatures

- Identifying new metrics for cladding performance (e.g., cladding stresses)

- Risk informing cladding performance (e.g., tolerance of peak cladding temperature, consequences to other safety disciplines)

- Defining staffs expectations for technical bases in support of a higher peak cladding temperature December 11, 2018 DSFM REG CON 2018 5