Liquid hydrogen cold moderator optimisation at the Budapest Research Reactor

Abstract At the Budapest Research Reactor (BRR) the main functional element of the planned cold neutron source (CNS) is a special moderator cell filled with liquid hydrogen and placed at the end of a horizontal beam channel in the Be reflector close to the maximum of thermal neutron distribution. The moderator cell is inside an explosion proof vacuum case preventing the reactor itself from any damage even in the worst oossible accident. Two versions of the moderator cell both directly cooled with cold He gas are compared.