Current U.S. activities and directions in shielding design for liquid-metal-cooled reactors

Accurate design of reactor shields is vital for extending component lifetimes, assuring reliable nuclear instrumentation, and reducing the capital and operating costs of modern reactors. In recent years, the emphasis in advanced reactor designs in the U.S. has been toward small compact systems that provide beneficial features of passive safety, modularity, and extensive shop fabrication. These compact designs, however, pose significant challenges from a shielding perspective because of the limited amount of space for shielding materials and the increasingly stringent requirements for plant dose reductions. The Shielding Development Program for the advanced liquid-metal-cooled reactor (ALMR) in the U.S. is currently involved in activities that seek to meet these challenges through the development and verification of new shielding design methodologies and innovative design features