Analysis of core temperature increase behavior in Fukushima Daiichi NPP Unit 2 by RELAP/SCDAPSIM

Yoshikawa, Shinji ; Sato, Ikken 

In the accidents of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), in contrast that core degradations are thought to begin before depressurization in Unit 1 and 3, the core of Unit 2 was presumed to be intact at the time of depressurization and the degradation is thought to begin when the liquid level was close to or below the bottom of the core. The authors analyzed a temperature increase behavior during the core degradation of Unit 2 based on simulations with RELAP/SCDAPSIM computer code.