Cover plug of the core of a fast neutron nuclear reactor

In a fast neutron nuclear reactor having a vessel closed by a structure comprising a rotating plug, said vessel containing a core and a coolant liquid, said nuclear reactor having control rods for movement into and out of said core, a cover plug structure for fixing and guiding the control rods and instrumentation of the core and deflecting and dispersing the coolant liquid, said cover plug structure comprising a cylindrical barrel having a vertical axis, a support plate integral with an upper part of the barrel for bearing on a rotating plug closing the vessel of the reactor in which vessel the core is immersed in the coolant liquid, a group of vertical tubes at least a part of which tubes receive control rods of the reactor, fixed in an upper part of the tubes to the support plate and disposed inside the barrel in a plurality of rows coaxial with the barrel, an apertured transverse plate fixed to a lower end of the barrel and allowing passage of the coolant liquid and the vertical tubes the spacing of which it ensures, and at least one transverse plate for deflecting the coolant liquid on which plate are fixed vertical tubes of the group which serve to effect measurements in the core, said deflecting plate the diameter of which is less than the inner diameter of the barrel being located inside the barrel above the apertured plate,

• the improvement wherein, for suspending the transverse deflection plate from the barrel, substantially vertical elastically yieldable strips are evenly spaced apart on the periphery of the barrel and welded to the barrel by an upper end of the strips and welded to an edge of the deflection plate by a lower end of the strips, openings being provided in the barrel in regions of the respective strips, said openings having a shape corresponding to the shape of the strips but with a slightly smaller size to allow movement of the strips outwards into the openings and of the deflection plate radially of said vertical axis, the deflection plate being integral with some of the tubes which receive control rods and are disposed in a single row coaxial with the barrel, the tubes thus ensuring the support of the deflection plate.