Development of Hydrogen Cold Moderator Systems for a Spallation Neutron Source

摘要

Hydrogen is at present the most realistic cold moderator material for a high-intensity spallation neutron source, although the neutronic characteristics are not as good as those of methane. Therefore, methods to improve the neutronic characteristic of the hydrogen moderator are required. Some methods to increase the neutron intensity and the pulse characteristics were tried for coupled and decoupled liquid hydrogen moderators. It was indicated for the coupled moderator that composite reflector and para-rich hydrogen were useful and for the decoupled moderator, a premoderator of water and also para-rich hydrogen were useful.