Reactor cover gas system for FBR type reactor

In an LMFBR type reactor, filters are disposed above coolants at low temperature and a reactor vessel submerged type vapor trap for passing cover gases through the low temperature coolants and exhausting them through the filters is disposed. Filters are disposed to the reactor roof deck. Cooling gas flow channels for the deck are extended to the circumference of the filters to cool the filters by the cooling gas. Further, a channel for communicating the cover gas exit with the bearing portion of a primary pump shaft supported on the reactor roof deck is disposed in the reactor roof deck. A circulation fan is disposed in the channel and the cover gases are recycled in the reactor structure while eleminating the cover gas supply system and the cover exhaust system at the outside of the reactor vessel. This can reduce the amount of materials amount and the installation space of the reactor cover gas systems. (T.M.)