Structural mechanics analysis of core support plate deflection for improvement of core deformation reactivity evaluation accuracy

Yoshimura, Kazuo; Doda, Norihiro  ; Igawa, Kenichi*; Uwaba, Tomoyuki ; Tanaka, Masaaki  ; Nemoto, Toshiyuki*

A sodium-cooled fast reactor has an inherent safety feature of feedback reactivity. Core deformation reactivity decreases fission power automatically in case of increase of the reactor power due to the negative reactivity according to raise of the core temperature. To improve the evaluation accuracy of the core deformation reactivity, deflection of the core support plate which varies the inclination of fuel assemblies and the pitches among them at the center height of the core and has impact on the reactivity was investigated quantitatively in the high flowrate and low flowrate conditions separately by structural mechanics analyses.