Solid neutron shield development. [Breeder reactors]

Solid neutron shields for use on Breeder Reactor Spent-Fuel Shipping Casks (SFSC) are being developed by Sandia Laboratories, Albuquerque, New Mexico. A number of different solid neutron shield materials are being evaluated which could be used to attenuate neutrons in various nuclear material transportation systems. A SFSC must be capable of surviving a series of design basis accidents (of which the fire would likely have the most severe effect on a neutron shield) with a degradation of shielding ability less than a factor of about one hundred. One basis of determining a preferable solid neutron shield material is to compare the neutron attenuation of the materials after being subjected to fire. Other bases include shielding efficiencies, costs, and mechanical properties. The materials currently being assessed as solid neutron shields for shipping casks are listed. The list includes one material that will remain undamaged and others that will degrade in a fire accident environment. The data base for the comparison of the materials is being compiled.