부산대학교 도서관

To improve the capability of the SAS4A code, which simulates the initiating phase of core disruptiveaccidents for MOX-fueled Sodium-cooled Fast Reactors (SFRs), the authors have investigated in detail thephysical phenomena under unprotected loss-of-flow (ULOF) conditions in a previous paper (Kawada andSuzuki, 2020) [1]. As the conclusion of the last article, fuel stub motion, in which the residual fuel pelletswould move toward the core central region after fuel pin disruption, was identified as one of the keyphenomena to be appropriately simulated for the initiating phase of ULOF. In the present paper, based on the analysis of the experimental data, the behaviors related to the stubmotion were evaluated and quantified by the author from scratch. A simple model describing fuel stubmotion, which was not modeled in the previous SAS4A code, was newly proposed. The applicability ofthe proposed model was validated through a series of analyses for the CABRI experiments, by which thestub motion would be represented with reasonable conservativeness for the reactivity evaluation ofdisrupted core