Design of Moderators and Reflectors for Chinese Spallation Neutron Source

Chinese Spallation Neutron Source (CSNS) is a significant research facility for studies of structure and dynamics of materials, which can play an important role in research and education. Moderators and reflectors system is one of the core components in CSNS. There are three moderators totally, namely, the decoupled and poisoned hydrogen moderator, the coupled hydrogen moderator and the decoupled water moderator. Moderators are inserted into an aluminum alloy vessel which contains beryllium and stainless steel reflectors. The moderators and reflectors are designed into a whole plug, MR Plug, so as to move the plug into or out of the core vessel of CSNS easily. The structure design of moderators and reflectors system is just finished now, including moderators, reflectors and their container. Neutronics requirements and strength criterions are satisfied, manufacture of system is feasible. Structure strength analyses of some parts are also presented.