Measurements of the heat deposition in moderators and decouplers in the ZING-P′ pulsed spallation neutron source

Abstract

Measurements of the nuclear power densities in moderator and decoupler materials irradiated in the prototype pulsed spallation neutron source, ZING-P′, have been performed to provide data necessary for the design of the Intense Pulsed Neutron Source. Polyethylene, beryllium, lead, liquid hydrogen and a boron-aluminum composite have been investigated. The heat deposition rates together with some other thermal characteristics have been determined from measurements of the rates of temperature rise. The power deposition and the temperature rise rate without heat loss in a polyethylene moderator test piece were found to be 1.34 mW/cm 3 and 0.042°C/min, respectively, with a 1.29 μA proton beam of energy 489 MeV on the 238U target. The measured power densities and cooling times of the various materials apply for samples placed 11.7 cm from the center of the neutron source, and are found to be in good agreement with calculated values. Thermal relaxation time constants determined for the various arrangements were also in good agreement with calculated values, giving added confidence to the results.