MODERATOR VESSEL FOR COLD NEUTRON SOURCE DEVICE

摘要

PURPOSE: To obtain uniform cold neutrons efficiently by constituting the vertical cross section of a vessel in the neutron movement direction in roughly funnel shaped. CONSTITUTION: Moderator 2 boils and generates bubbles 11 due to nuclear heating such as fast neutrons mixed in thermal neutrons and -ray etc. Even in the case that bubble 11 existence is larger for higher elevation in the moderator vessel 1, relative existence amount of moderator 2 does not reduce as the vertical cross section is roughly funnel shaped, practical length of movement of thermal neutrons in the moderator becomes constant, and cold neutrons can be obtained efficiently and uniformly in the whole vessel 1. Also, as the upper open wall surface is slanted, bubbles 11, if generated, move up smoothly without stagnation of bubbles 11, which brings in a benefit to stabilize the cold neutron.