抄録
The purpose of this paper is to study the core performance of passive safety small reactor for distributed energy supply by changing the boric acid(H_BO_) concentration in the mixed coolant together with the fuel pitch. The long core life with conditions of the excessive reactivity of 2 %Δk/k and the reactivity shutdown margin of 1 %Δk/k. This boron core has almost the same core life as the original light water (H_O) core of 4.76 years, while it needs a larger core size. However, changing the boron concentration on the way during the burn-up shows a possibility of extending more the core life than that of the original H_O core.
