Threat of Hydride Re-orientation to Spent Fuel Integrity During Transportation Accidents: Myth or Reality?
- ANATECH, 5435 Oberlin Drive, San Diego, CA 92121 (United States)
- EPRI, 3420 Hillview Avenue, Palo Alto, CA 94304 (United States)
The source-term study conducted by Sandia National Laboratories nearly two decades ago for the spent fuel inventory known at the time, which was in the low-to-medium burnup range ({approx}35 GWd/MTU), showed that the effects of transportation accidents on spent fuel failures, and consequential radioactivity release to the environment, were relatively benign. However, with today's discharged fuel burnups routinely greater than 45 GWd/MTU, potential hydride reorientation during interim dry storage, and its effects on cladding properties, has become one of the primary concerns for spent fuel transportation. Laboratory tests of un-irradiated cladding specimens subjected to heat treatments promoting hydride dissolution followed by re-precipitation in the radial direction have shown that relatively moderate concentrations ({approx}70 ppm) of radial hydrides can significantly degrade cladding ductility, at least at room temperature. The absence of specific data that are relevant to high-burnup spent fuel under dry storage conditions have led to the conjecture, deduced from those tests, that massive cladding failures, possibly resulting in fuel reconfiguration, can be expected during cask drop events. Such conclusions are not borne out by the findings in this paper. The analysis results indicate that cladding failure is bi-modal: a state of failure initiation at the cladding ID remaining as part-wall damage with less than 2% probability of occurrence, and a through-wall failure at a probability of 1 E-5. These results indicate that spent fuel conditions that could promote the formation of radial hydrides during dry storage are not sufficient to produce radial hydrides concentrations of significant levels to cause major threat to spent fuel integrity. It is important to note in this regard that the through-wall cladding failure probability of 1 E-5 is of the same order of magnitude as calculated in the cited Sandia study for low burnup fuel. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 21229312
- Resource Relation:
- Conference: 2007 LWR Fuel Performance Meeting / TopFuel 2007, San Francisco, CA (United States), 30 Sep - 3 Oct 2007; Other Information: Country of input: France; 10 refs; Related Information: In: Proceedings of the 2007 LWR Fuel Performance Meeting / TopFuel 2007 'Zero by 2010', 683 pages.
- Country of Publication:
- United States
- Language:
- English
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