RCCA ejection fault studies; Application of a burnup threshold for the evaluation of the radiological releases

高燃焼度PWR燃料のNSRR実験に基づくPCMI破損限界の破壊力学的評価

宇田川 豊  ; 杉山 智之 ; 鈴木 元衛; 永瀬 文久 

Udagawa, Yutaka; Sugiyama, Tomoyuki; Suzuki, Motoe; Nagase, Fumihisa

In PCMI failure of high-burnup PWR fuel claddings under RIA conditions, small cracks are generated in the accumulated hydride clusters, called "hydride rim", one of these cracks penetrates inward, and it finally causes the through-wall crack. On the basis of such understanding, we performed an extensive evaluation of the fracture parameter J-integral for as many high-burnup PWR fuel tests in the NSRR experiment database as possible in order to treat all the PCMI failure cases comprehensively and discuss effects of temperature and hydrogen content on PCMI failure limit. The evaluated critical J values were well correlated with both hydrogen content and crack tip temperature and thus we have designed a tentative PCMI failure criterion with critical J values as an analytical function of cladding average hydrogen content and crack tip temperature.