Design considerations for penetrations in the TFTR radiation shield

The design of a radiation shield for the TFTR (Tokamak Fusion Test Reactor) D-T operation must take into account the fact that many machine components and diagnostics require penetrations through the shield. The design considerations and neutronics analyses leading to the final designs for various penetrations in the shield are described. Included are the considerations for the material selection, the penetration locations, and the sizes of the back and side shields required to prevent hot spots. The consequences of leaving minor diagnostic penetrations unshielded are addressed