Neutronic optimization of premoderator and reflector for decoupled hydrogen moderator in 1MW spallation neutron source

Harada, Masahide; Teshigawara, Makoto   ; Kai, Tetsuya   ; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro

For a decoupled hydrogen (super critical) moderator, optimization studies have been performed on a premoderator and reflector material (Pb, Be, Fe and Hg) together with the decoupling energy to realize a higher neutronic performance. The result indicated that the best neutronic performance could be obtained for a decoupled H moderator in a Pb reflector by optimizing the premoderator and adopting an appropriate decoupling energy, even compared with optimized one in a Be reflector.