Alteration of reactor installation (alteration of criticality experiment facilities) in General Research Institute, Nippon Genshiryoku Jigyo K.K. (report)

The Nuclear Safety Commission presented the report to the Prime Minister after the prudent deliberation on the above alteration, about which the inquiry had been made on May 23, 1988. It was recognized as the result of examination that the technical capability of the applicant is appropriate. It was judged as the result of examination that the safety after this alteration of reactor installation can be ensured. In order to carry out the reactor physics experiment on the improved core of BWRs, in which the initial degree of enrichment was heightened, and on the techniques of fuel storage, among the fuel elements permitted already, the number of the rod type fuel elements of 3.9% and 4.9% enrichment is increased, and the range of the volume ratio of water to fuel is extended from 1.5 - 3.0 to 0.2 - 3.0. As for the safety design, the analysis of the nuclear characteristics, the main dynamic characteristic parameters, the maximum power output and the specification of fuel elements were examined. Also the safety evaluation in accidents and mistaken operation was carried out. Thus the safety was confirmed. (K.I.)