An investigation into sliding bearings suitable for a CO 2-cooled nuclear reactor

Abstract

In a nuclear reactor a number of mechanisms are required to operate up to about 400/dgC, often in the presence of intense radiation fluxes. Three possible solutions to the problem of making bearings for these mechanisms are discussed; the use of unlubricated metals, of massive graphite, and of thin graphite films on a metal base. Three metals, two nitrided steels and a tool steel, have been found to run well unlubricated, both against themselves and a variety of other steels. Coefficients of friction for unlubricated metals are high, usually in the range 0.3 to 0.8 but tending on occasions towards unity. An electrographite was found which would run satisfactorily in dry CO 2 but the performance in dry air, dry nitrogen and in a vacuum was poor. Thin graphite films have been found to have too unpredictable a life for practical purposes.