United States Nuclear Regulatory Commission - Protecting People and the Environment

Dry Storage and Transportation of High Burnup Spent Nuclear Fuel – Draft Report for Comment (NUREG-2224)

This NUREG-series publication was issued for public comment. The comment period is now closed.

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Publication Information

Manuscript Completed: April 2018
Date Published: July 2018

Prepared by:
T. Ahn
H. Akhavannik
G. Bjorkman
F.C. Chang
W. Reed
A. Rigato
D. Tang
R.D. Torres
B.H. White
V. Wilson

Office of Nuclear Material Safety and Safeguards
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Time-dependent changes on the cladding performance of high burnup (HBU) spent nuclear fuel (SNF) are all primarily driven by the fuel's temperature, rod internal pressure (and corresponding pressure-induced cladding hoop stresses), and the environment during dry storage or transport operations. Historically, the potential for these changes to compromise the analyzed fuel configuration in dry storage systems and transportation packages has been addressed through safety review guidance. This guidance defines adequate fuel conditions, including peak cladding temperatures during short-term loading operations to prevent or mitigate degradation of the cladding. The purpose of this report is to expand the technical basis in support of that guidance, as it pertains to the mechanism of hydride reorientation in HBU SNF cladding.

Hydride reorientation is a process in which the orientation of hydrides precipitated in HBU SNF cladding during reactor operation changes from the circumferential-axial to the radial-axial direction. Research results over the last decade have shown that hydride reorientation can still occur at temperatures and stresses lower than those assumed in the current staff review guidance. Therefore, the U.S. Nuclear Regulatory Commission (NRC) has since sponsored additional research to better understand whether hydride reorientation could affect the mechanical behavior of HBU SNF cladding and compromise the fuel configuration analyzed in dry storage systems and transportation packages.

This report provides an engineering assessment of the results of research on the mechanical performance of HBU SNF following hydride reorientation. Based on the conclusions of that assessment, the report then presents example approaches for licensing and certification of HBU SNF for dry storage (under Title 10 of the Code of Federal Regulations (10 CFR) Part 72, "Licensing Requirements for the Independent Storage of Spent Nuclear Fuel and High-Level Radioactive Waste, and Reactor-Related Greater Than Class C Waste") and transportation (under 10 CFR Part 71, "Packaging and Transportation of Radioactive Material").

The information in this report is not intended for use in applications for wet storage facilities or monitored retrievable storage installations licensed under 10 CFR Part 72.

Nothing contained in this report is to be construed as having the force or effect of regulations Comments regarding errors or omissions, as well as suggestions for improvement of this NUREG should be sent to the Director, Division of Spent Fuel Management, U.S. Nuclear Regulatory Commission, Washington, D.C., 20555-0001.

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Page Last Reviewed/Updated Tuesday, November 13, 2018