FBR type reactors

Purpose: To improve the wetting performance between freeze-sealing metals and partition plates thereby surely prevent cover gases from leakage in a FBR type reactor having a rotational shielding plug applied at the sliding surface thereof with sealing metals for preventing gas leakage. Constitution: The reactor comprises core upper mechanims provided practically at the center of a rotational plug for engagement with a stationary plug provided to the opening end of a reactor vessel, a sealing chamber formed to a part of the rotational plug, partition plates disposed to the stationary plug while extended to the inside of the chamber and freeze-sealing metals stored in the sealing chamber. The surfaces of the sealing chamber and the partition plates in contact with the sealing metals are covered with such metals as capable of forming solid solution with at least one component of a composition for the sealing metals and have a melting point higher than that of the sealing metals. The molten sealing metals diffuse in the surfaces of the sealing chamber and the partition plates to improve the wettability. (Horiuchi, T.)