Fast reactor fuel pin behavior analyses in a LOF type transient event

Mizuno, Tomoyasu; Koyama, Shinichi  ; Kaito, Takeji ; Uwaba, Tomoyuki ; Tanaka, Kenya

In order to evaluate integrity limiting parameters of fuel pins during fast reactor core transient events, such as fuel center line temperature and cladding maximum temperature, the fast reactor fuel pin performance code CEDAR was used for calculation. The temperature histories of fuel pins during a loss of flow (LOF) type transient events was calculated based on Ross & Stoute type gap conductance model and constant gap conductance model used in a core transient calculation code like HIPRAC. The calculated maximum temperatures of cladding and adjacent coolant channel were lower in the case with Ross & Stoute type model than in the case of constant gap conductance model due to the dynamic change of gap conductance of the former case. It is indicated that core transient calculations with constant gap conductance give conservative cladding and coolant temperatures than that with Ross & Stoute type gap conductance model which is thought to be realistic.