JPH0138277B

A side reflector for a gas-cooled nuclear reactor is in the form of a hollow cylinder built up of graphite blocks; outward thrust from this cylinder resulting from the internal pressure of the pebble bed core is resisted by supports or props bearing against the surrounding thermal shield and liner. The faces of the reflector blocks which are towards the inside and thus constitute the inner face of the side reflector are at varying distances from the central axis of the reactor. Used for a gas-cooled pebble-bed reactor. It is found that the retarding effect exerted by the side reflector upon the descent of the fuel elements during the life of the core is highly attributable to the orderly arrangement of fuel elements in the outer layers of the core which becomes established after a certain period. By arranging for different blocks to project into the core space by slightly differing amounts, this orderly effect is broken up and thus the retarding effect upon the descent of the fuel elements is considerably reduced.