Outline of 800 MWe HTGR project in Japan

The basic design of an 800 MW HTGR designed by General Atomic Company (GA) was modified from the viewpoint of aseismatic construction. Particularly, the restricting construction for supporting a reactor core, the supporting construction of a PCRV, and a fuel handling facility were studied. The principle of such study was based on the following conditions: (1) the reactor-housing building shall be an independent building, (2) the auxiliary building for the reactor and the control building shall be the construction of most advantageous dynamic behavior, (3) the floating foundation at the time of dynamical analysis may be allowed, if the response and characteristics by non-linear analysis are not questionable. The following points were modified after the study. The mat foundation of the reactor housing was made larger, and the penetration building was made in one body with this base. The type of the supporting construction of a PCRV was changed to wheel type. The thickness of PC containment vessel was made larger than original one. The base of the auxiliary building and the base of the control building were incorporated. Number of spring packs was increased from 210 to 330. The height of permanent reflector was reduced. The diameter of periphery of the core supporting post was increased from 7-3/4 inches to 9 inches. The horizontal restriction mechanism was constructed with bi-linear springs. (Iwakiri, K.)