Validation of updated RANNS with effect of oxygen-dissolved metallic zircaloy-4 under LOCA quench condition

冷却材喪失事故条件下の燃料挙動に及ぼす被覆管金属層酸素濃度の影響; 事故時燃料挙動解析コードRANNSによる解析

Wu, H.; 宇田川 豊  ; 成川 隆文 ; 天谷 政樹  

Wu, H.; Udagawa, Yutaka; Narukawa, Takafumi; Amaya, Masaki

Loss-of-Coolant-Accident (LOCA) is a classical design basis accident considered in LWR safety analyses, and LOCA simulation technique can be used to gain a better understanding of local cladding behaviors. This paper first summarizes equations regarding the oxygen-dissolved metallic Zircaloy-4 layer (ODMZ). These equations have been added to the updated RANNS code, which is validated using LOCA quench experimental data. The update RANNS code is then used to examine the influence of ODMZ and the oxide layer on its axial load under LOCA quench conditions. The results suggest that the contribution of both the ODMZ and the oxide layer to the axial load increase with oxidation time, and the latter increases more in a fixed length of oxidation time. This study shows the importance and necessity of considering the effect of the ODMZ when computing the axial load on cladding in LOCA quench conditions.