Solid Methane Cold Moderator for the IBR-2 Reactor

Abstract

This paper covers test runs made with the cold moderator prototype at the IBR-2 reactor running at 2 MW. The cold neutron intensity gain is shown to be 14–25 as predicted. Periodic annealing of the cold moderator, carried out to relieve radiolytically derived hydrogen, created a significant improvement in cold neutron intensity. Unfortunately, some cracks appeared in the methane chamber toward the end of the tests, but close analysis indicated that this problem could be addressed by the design modifications described at the end of this paper.