Research and development of HTR related technology, (6)

In multi-purpose high temperature gas-cooled reactors, definite description is very hard how concrete pressure vessels, exactly prestressed concrete pressure vessels (PCPV), can be applied. This report reviews their structural characteristics centering around the design concept of PCPVs. The design criteria for PCPVs are different a little in various countries. The U.K. has established them as one of British Standards officially. In France, the technical guideline has been proposed in 1969. In the U.S., the draft of the criteria has been proposed as they form a part of the ASME boiler and pressure vessel code. In Japan, there is no such trend as establishing standards though the draft of technical criteria for concrete pressure vessels was prepared in 1979. In addition, the present status of providing safety margin for the structural strength and internal pressure rupture test in respective countries is also explained. The method to introduce compression which is equivalent to cancel the concrete tensile stress generated in PCPVs when designing is four-fold, and each method is described. The pressure vessels are obliged to be subject to pressure test (1.15 times the design pressure) when completed. The vessels are also obliged to be monitored during operation. In addition, the aseismic capability must be investigated in Japan. The aseismic reliability proof test for light water reactor structures is planned for coming 7 years in Nuclear Engineering Center, and it will furnish useful information to the high temperature gas-cooled reactors. (Wakatsuki, Y.)