IMPROVEMENTS IN OR RELATING TO NUCLEAR REACTORS

摘要

1279084 Reactors UNITED KINGDOM ATOMIC ENERGY AUTHORITY 3 Nov 1969 [15 Nov 1968] 54439/68 Heading G6C A liquid metal (e.g. sodium) cooled fast breeder reactor has a core configuration which includes a central cylindrical breeder region, a first fissile region which completely embraces the central breeder region, a second fissile region at least partially surrounding the first fissile region with axial and radial clearance, an inner breeder region occupying this clearance, and an outer breeder region extending both axially and radially from the outer boundary of the second fissile region to the cylindrical core boundary. In a preferred construction, shown in Fig. 2, the second fissile region only partially surrounds the first fissile region, the " corner " fissile portions of a wholly surrounding fissile region being replaced by breeder material. The annular region between the first and second fissile regions, i.e. the region bounded on the inside by lines 13, 131 and on the outside by lines 14, 141, is therefore entirely breeder and of full core height. Because of the lower heat rating of breeder pins, it may comprise fuel pins of greater diameter than those which include fissile material, thus enabling a higher breeder/ structural material ratio to be achieved. The radially outermost region comprises similar fuel pins. Preferably, the fissile material is mixed U and Pu oxides, and the breeder material is UC.