Effects of three-dimensional steam flow on exit temperatures during core boil-off in PWR vessel top break LOCA simulation experiments by using ROSA/LSTF

Suzuki, Mitsuhiro; Takeda, Takeshi ; Asaka, Hideaki; Nakamura, Hideo  

A core fluid temperature distribution which is considered to be affected by both high-temperature steam flow towards the control rod cluster guide tubes and low-temperature steam flow affected by non-heating structural materials especially in the core peripheral regions was detected during a core boil-off condition in PWR vessel top break LOCA simulation experiments conducted at ROSA/LSTF to study effectiveness of accident management measures in the OECD/NEA ROSA project. Reported are these three-dimensional steam flows in the core and their influences on detection of the super-heated temperatures at the core exit.