Validation of plant dynamics analysis code for fast reactor core thermal hydraulics under natural circulation conditions

Hamase, Erina ; Doda, Norihiro  ; Nabeshima, Kunihiko  ; Ono, Ayako ; Ohshima, Hiroyuki

Under natural circulation decay heat removal conditions, three characteristic phenomena; flow redistribution in the core as well as in the fuel subassemblies, inter-subassembly heat transfer and gap flow between wrapper tubes of fuel subassemblies are important for assessing the temperature distribution in the core. In order to improve the prediction accuracy, a whole core model which can consider these three phenomena has been incorporated into the plant dynamics analysis code Super-COPD. In this study, analyses of two kinds of sodium experiments were performed to validate Super-COPD with the whole core model, which were focusing on inter-subassembly heat transfer phenomena.