Effects of wire spacer contact and pellet-cladding eccentricity on fuel cladding temperature under natural circulation decay heat removal conditions in sodium-cooled fast reactor

Doda, Norihiro  ; Ohshima, Hiroyuki; Kamide, Hideki ; Watanabe, Osamu*; Okubo, Yoshiyuki*

Toward the commercialization of fast reactors, design study of JSFR is being performed. Adoption of fully natural circulation system is being examined as the decay heat removal system. In order to confirm feasibility of the system, we are developing a new evaluation method of core hot spot in transition from rated operation to natural circulation decay heat removal conditions, which requires uncertainty factor assessment for the natural circulation conditions as well as for the rated operation conditions. In this paper, we focus on effects of wire-spacer contact and pellet- cladding eccentricity on the peak cladding temperature as typical uncertainty factors and evaluated these two effects under natural circulation conditions quantitatively.