Thermal hydraulic design study on the accelerator driven subcritical reactor

An accelerator driven subcritical reactor (ADSR) is an apparatus to double neutron formed by a spallation neutron source by using subcritical nuclear fuel system, and is recently focussed as a new nuclear energy system upgrading safety extremely without possibility of critical accident. However, at present a number of research subjects such as nuclear properties, fuel and its materials, thermal properties, and so forth on formability of this system for an actual nuclear energy system are remained to investigate them. At the Research Reactor Institute, Kyoto University, as a part of basic research on accelerator driven subcritical reactor, some studies on its target cooling has been carried out. Hitherto, investigations of application of a calculation equation to thermal hydraulic design on spallation neutron source solid target on a base of heat transfer experimental results on a solid target were conducted. As a result, it was found that as limitation of beam power due to critical hat flux (CHF) became 8.6 MW, it was 3.5 MW at its boiling control condition. And, when limiting maximum temperature under 200degC, it became 4 MW. As in this calculation, changes of production error and operative condition on the target and safety tolerance considered with errors of the calculation equation and so forth are contained in an actual calculation, a beam power capable of realizing is thought to be relatively lower because of requirement for adequate safety tolerance on consideration of these errors and uncertainties. (G.K.)