Core deformation reactivity with neutronics-thermal hydraulics-structural mechanics coupled analysis for FFTF LOFWOS Test #13

Doda, Norihiro  ; Kato, Shinya ; Uwaba, Tomoyuki ; Tanaka, Masaaki ; Nakamine, Yoshiaki*; Igawa, Kenichi*; Iida, Masaki*

Accurate evaluation of reactivity feedback due to core deformation during power increases in sodium-cooled fast reactors requires comprehensive modeling of the interactions among neutronics, thermal-hydraulics, and core mechanics. To accurately consider these interactions, JAEA has developed an evaluation method that combines multiple analysis codes that model these phenomena in detail. In this study, the evaluation method was applied to the core analysis of the FFTF LOFWOS Test #13, and the analysis results of net reactivity were compared with the test results. The sensitivity analysis results of the core structural design parameters showed that the core bowing behavior has a significant effect on the temporal variation of net reactivity.