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

It is important to control the chemistry of the helium coolant used in high-temperature gas-cooled reactors (HTGRs). The effect of a decarburizing environment on the creep rupture properties tends to decrease the creep rupture life of the heat-resistant alloy used in heat exchangers. In this paper, we describe an active control method for the concentration of impurities using the existing helium purification system, which consists of a helium heater, a copper oxide trap (CuOT), a molecular sieve trap, a cold charcoal trap, and a bypass line. Analysis showed that the efficiency control of CuOT is effective in improving the decarburizing atmosphere. The efficiency control of CuOT increases the concentrations of carbon monoxide and hydrogen. It was found that both the enrichment of carbon monoxide suggested in previous studies and the enrichment of hydrogen are also effective in forming the carburizing atmosphere.