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Abstract

The effective diffusion coefficient that gives a steady-state xenon concentration of 0.2-0.3wt% in the re-crystallised grains of high burn-up UO2 fuel is calculated to lie in the range 10{-24} to 10{-22}m{2} s{-1}. These values are one to three orders of magnitude lower than the value currently accepted for the radiation-enhanced diffusion coefficient. The time required to reach the steady-state concentration depends on the local fission rate, the grain size distribution and the precise magnitude of the radiation-enhanced diffusion coefficient, and can take from 2 to 10 years. Additional calculations reveal that substantially less than 10% of the fission gas inventory is released from the original UO(2) grains in the outer region of the fuel prior to re-crystallisation. In contrast, with a diffusion coefficient of 10{-22}m{2}s{-1} more than 80% of the fission gas is released from the re-crystallised grains of the high burn-up structure in one year.

Additional information

Authors: BRÉMIER S, European Commission, Joint Research Centre, Institute for Transuranium Emements, Karlsruhe (DE);WALKER C T, European Commission, Joint Research Centre, Institute for Transuranium Emements, Karlsruhe (DE)
Bibliographic Reference: An article published in: Radiation Effects and Defects in Solids, Volume 157, Number 3/2002, pp.311-322.
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://taylorandfrancis.metapress.com/openurl.asp?genre=issue&issn=1042-0150&volume=157&issue=3
Record Number: 200215694 / Last updated on: 2002-12-23
Category: PUBLICATION
Original language: en
Available languages: en
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