Evaluation of material properties of IG-430 graphite for next generation high temperature gas-cooled reactor

Kunimoto, Eiji*; Sumita, Junya ; Osaki, Takashi*; Osaki, Hiroki*; Yamaji, Masatoshi*; Konishi, Takashi*

Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor (HTGR) which is a graphite-moderated and helium gas-cooled reactor. The major features of the HTGR are that the HTGR can take out the high-temperature helium gas at the reactor outlet and has inherent safety characteristics. The Very High Temperature Reactor (VHTR) is one of the most promising candidates as the Generation-IV nuclear reactor systems. IG-110 graphite having high strength and resistance to oxidation is used in the HTTR of JAEA and HTR-10 in China. Moreover, IG-110 graphite provides highly consistent quality and long-term stable supply. IG-110 graphite is a major candidate for the in-core graphite components of VHTR. IG-430 graphite having the higher strength and resistance to oxidation than IG-110 is an advanced candidate for the VHTR. However, a new material of IG-430 does not have enough databases for the design of HTGR. Therefore, preparation of the necessary database for the design, mechanical and thermal properties, irradiation effect on them, is underway. In this study, the tensile strength, compressive strength and fatigue strength of IG-430 were statistically evaluated and the applicability of IG-430 as HTGR graphite materials was discussed. Moreover, the Su value of tensile and compressive strength of IG-430 was evaluated and compared to that of IG-110. It was found that IG-430 has excellent properties.