Research and development on aseismatic problems of HTGR core

The core of HTGRs is constructed with 8000 graphite blocks of hexagonal prism with gaps in horizontal direction, and the behavior of the core at the time of earthquakes is expected to be very complicated involving the mutual collision of the graphite blocks. It is indispensable to examine sufficiently and prove the safety with the data and by the evaluation method of Japan proper concerning the aseismatic capability of the core. In Japan, Electric Power Development Co. decided the systematic research and development project on this problem in 1973 on the basis of the state of research and development in GA Corp., USA, and has continued the effort. The elucidation of the collision phenomenon of graphite elements at the time of earthquakes by model experiment, the development of the analysis code, and the tests on graphite blocks and core-supporting posts have been carried out in GA since 1968. In Japan, the development of the computing code for the estimation of graphite block behavior at the time of earthquakes and the confirmation of the provableness of the computing code by model experiment are the main subjects, and the establishment of the evaluation method for aseismatic capability of Japan proper is aimed at. Now a half of the second research and development is finished, and the third research and development will be completed about two years hereafter. (Kako, I.)