Safety strategy of JSFR eliminating severe recriticality events and establishing in-vessel retention in the core disruptive accident

Sato, Ikken ; Tobita, Yoshiharu; Konishi, Kensuke ; Kamiyama, Kenji  ; Toyooka, Junichi  ; Nakai, Ryodai ; Kubo, Shigenobu* ; Kotake, Shoji*; Koyama, Kazuya*; Vassiliev, Y. S.*; Vurim, A.*; Zuev, V.*; Kolodeshnikov, A.*

In the JSFR design, elimination of severe recriticality events in the Core Disruptive Accident (CDA) is intended as an effective measure to assure retention of the core materials within the reactor vessel. The design strategy is to control the potential of excessive void reactivity insertion in the Initiating Phase selecting appropriate design parameters such as maximum void reactivity on one hand, and to exclude core-wide molten-fuel-pool formation, which has been the main issue of CDA, with introduction of Inner Duct on the other hand. The effectiveness of these measures are reviewed based on existing experimental data and evaluations performed with validated analysis tools. It is judged that the present JSFR design can exlude severe power burst events.