Neutron-photon transport studies for the optimisation of radial shielding in a fast reactor

In the design of a fast breeder reactor the effectiveness of the radial shielding has a large impact on the overall size of the reactor vessel and hence on the cost of the design. These radial shields serve the purpose of reducing the neutron flux to a levels such that the secondary sodium activity is within permissible limits. As the leakage neutron flux from the fast reactor has a comparatively fast spectrum, the shielding consists of materials such as steel, boron carbide etc. The radial shield for a prototype fast breeder reactor have been optimised considering different materials of varying thicknesses. In this paper, optimisation studies with various materials and also studies made to validate the calculation and studies with an alternate cross section set are reported. (author). 7 refs., 1 tab