Failure and its mechanism of LWR and research reactor fuels

YANAGISAWA Kazuaki

Policy Planning and Administration Department, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma, 370-1292 Japan (yanagisawa.kazuaki@jaea.go.jp)

Abstract: A failure of LWR fuel under a normal operating condition up to the burn-up of 20MWd/kgU was PCI-SCC. A failure of LWR fuel under RIA occurred at 260cal/g・fuel for the fresh fuel and 118cal/g・fuel for pre-irradiated PWR fuel to 42MWd/kgU. The mechanism was the melt-brittle for the former and strong PCI combined with transient FGR for the latter. The silicide fuel failed by the through-plate cracking, where the tensile thermal stress governed by temperature drop (>94deg.C) and time to quench (<0.13s) is the principal mechanism.

Keywords: LWR fuel; silicide fuel; PCI failure; transient FGR; melt-brittle failure; through-plate cracking; RIA