THERMAL NEUTRON BEHAVIOR IN SHIELD DUCTS.

The behaviour of thermal neutrons in a water shield containing ducts was studied experimentally and compared with theoretical models. In addition to measuring the total flux, a source separation technique was used to isolate the various flux components, which are: direct component, uncollided neutrons which enter the duct mouth; scattered component, collided neutrons which enter the duct mouth; and penetration component, collided neutrons which originally enter the shield. Duct diameters from 1 1/8 in. to 4 in. were considered. The shield absorption properties were altered by dissolving various amounts of boric acid in the water. (auth)