Control method of purification system of helium coolant for suppressing decarburization of heat-resistant alloy used in very high temperature gas cooling reactors

Hamamoto, Shimpei  ; Sakaba, Nariaki ; Takeda, Yoichi*

Chemistry control is important for the helium coolant of High Temperature Gas-cooled Reactors (HTGRs). Decarburizing atmosphere reduced creep rupture strength of the heat resistant alloy using for the heat exchanger. This paper describes active control of impurities concentration using existing helium purification system which consists of helium heater, Cupper oxide bed (CuOT), Molecular sieve bed, Cold Charcoal bed and each bypass line. Analysis showed that efficiency control of CuOT is effective in an improvement of decarburizing atmosphere. This effect is based on that H which is not removed cause the increase in carbon monoxide effective in formation of carburizing atmosphere by water-gas-shift reaction.