Improvement of reactivity model of core deformation in plant dynamics analysis code during unprotected loss of heat sink event in EBR-II

Yoshimura, Kazuo; Doda, Norihiro  ; Fujisaki, Tatsuya*; Igawa, Kenichi*; Tanaka, Masaaki  ; Yamano, Hidemasa   

The benchmark analyses for the unprotected loss of heat sink (ULOHS) tests in the pool-type experimental SFR in the United States, EBR-II (BOP-301 and BOP-302R) have been conducted in order to validate the evaluation method of the reactivity feedback equipped in the plant dynamics analysis code named Super-COPD. In this study, 1D-CFD coupled analyses adding the core bowing reactivity model were conducted. Through the analysis, the applicability of the modified reactivity model was confirmed for the BOP-301 test. For the BOP-302R test, consideration of the core restraint system in the core and modeling the control rod driveline expansion reactivity was indicated.