Conceptual design of small-sized HTGR system, 2; Nuclear design

Goto, Minoru  ; Seki, Yasuyoshi; Inaba, Yoshitomo  ; Ohashi, Hirofumi ; Sato, Hiroyuki  ; Fukaya, Yuji   ; Tachibana, Yukio 

Japan Atomic Energy Agency has started a conceptual design of a small-sized HTGR with 50 MW thermal power (HTR50S), which is a first-of-a-kind commercial or demonstration plant of a small-sized HTGR to be deployed in developing countries in the 2020s. The nuclear of the HTR50S was performed by upgrading the proven technology of High Temperature Engineering Test Reactor (HTTR) to reduce cost for the construction. In the nuclear design, reduce the number of fuel enrichment comparing with the HTTR is one of the important subject to be upgraded. The optimization of the power distribution in the core, which is required to suppress the maximum fuel temperature below the limitation, was completed successfully by using only three fuel enrichment and the number of fuel enrichment was reduced significantly compared with the HTTR.