Abstract
The high temperature helium gas loop, which is used for irradiation tests of the nuclear fuels of the gas cooled reactors, is constructed in JAERI(Japan Atomic Energy Research Institute). Since the maximum temperature of the helium gas coolant in the gas loop is1000°, it is necessary that the concentration of impurities present in the helium gas coolant is held less than10ppm to prevent the corrosion of structural materials. To obtain the design data of the helium coolant purification system, the outgassing behavior of the structural materials such as graphite and ceramic thermal insulator was measured by mass spectrometer and gas chromatograph. It is found by this study that the outgassing rate from graphite and ceramic thermal insulator can be expressed by the following equation, s(t)=Ge-ktt2.
