Abstract: A cylindrical pressure chamber, designed to contain a hot expanding fluid in a nuclear reactor, has a refractory peripheral wall provided with a cooled metal lining surrounding a ceramic insulating layer which is shielded from the fluid by an inner metallic shell. The shell is separated from the ceramic layer, in the nonoperating state, by an annular clearance allowing its expansion under internal fluid pressure to pretension that shell so as to reduce the thermally induced stress to less than the yield point of the metal. The ceramic layer is anchored to the lining by radial bolts and has radial bores slidably engaged by guide studs welded to the shell.FIELD OF THE INVENTIONMy present invention relates to a cylindrical pressure chamber designed to contain a hot expanding fluid, more specifically a pressure chamber used in a nuclear reactor.