Development of graphite sealing technique for an irradiation test rig of nuclear fuels

Abstract

To test a newly developed nuclear fuel, a test rig needs to be made and put into the core of a research reactor. Then, high temperature and highly pressurized coolant is circulated through the test rig during the irradiation test to transfer the heat generated by the fissile activity of the nuclear fuel. Because several decades of instrumentation cables are drawn from a test rig, it is difficult to seal out the coolant in the test rig. In this study, a mechanical sealing method which uses flake type graphite powder has been developed to replace the conventional brazing process. The internal design of the test rig is modified to apply compressive stress on the graphite powder to seal out the gap between the sealing plug and instrumentation cables. The sealing performance is then verified by a hydraulic pressure test and Helium leak test according to the ASME code, section III.