抄録
Basic policy of maintenance was determined for major equipment in the power conversion system of the Gas Turbine High Temperature Reactor 300 (GTHTR300). It was developed based on the current maintenance practice in Light Water Reactors (LWRs), High Temperature Engineering Test Reactor (HTTR) and conventional combined cycle power plants while taking into account of unique design features of GTHTR300. First, potential degradation phenomena in operations were identified and corresponding maintenance approaches were proposed for the equipment. Such degradations encountered typically in LWRs as corrosion, erosion and stress corrosion cracking are unlikely to occur since the working fluid of GTHTR300 is inert helium. Main causes of the degradations are high operating temperature and pressure. The gas turbine, compressor, generator, control valves undergo opening and dismantling maintenance in a suitable time interval. The power conversion vessel, heat exchanger vessel, primary system piping and heat exchanging tubes of precooler are subjected to in-service inspections similar to those done in LWRs. As turbine blades represent the severest material degradation because of their high-temperature and high-stress operating conditions, a lifetime management scheme was suggested for them. The longest interval of open-casing maintenance of the gas turbine is estimated to be six to seven years from technical point of view. Present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
