Non-condensable Gas Generation Behavior in High-temperature Lithium Heat Pipe under Irradiation

In the new type of heat pipe cooling reactor, the high-temperature metal heat pipe will be continuously irradiated by neutrons. The neutron reaction micro section of lithium in the thermal neutron zone is very large, and a certain amount of helium gas will be generated. As a non-condensable gas, helium gas will affect the normal operation of high-temperature heat pipes. The influence of neutron irradiation conditions in the reactor on the non-condensable gas generation characteristics in high-temperature lithium metal heat pipes was analyzed. First, the steady-state standard example was analyzed for helium production, and the volume fraction of non-condensable gas was converted. In addition, the change of the non-condensable gas output with the heat pipe filling amount, the enrichment of lithium metal, the neutron flux density, the heat pipe operating temperature and other factors was obtained. It can be seen that the output of non-condensable gas increases with the heat pipe filling volume and the lithium enrichment, and when the control drum is located at different angles, the neutron flux density changes are limited, so it affects the helium production not large, because the operating temperature of the high-temperature lithium heat pipe is very high, and the microscopic cross section of the neutron reaction at high temperature is not large, so the effect of the heat pipe operating temperature on the helium production is also limited. This study can provide reference guidance for the design of lithium enrichment in high-temperature lithium heat pipes in heat pipe cooling reactors.