Thermal hydraulics designs of a solid target for a spallation neutron source

R and D studies were reported on the thermal hydraulics designs of a water-cooled solid target system in the spallation reactor for N-arena of Japan Hadron Facility (JHF). Targets for the proton beams of 3 GeV, 0.6 and 1.2 MW and having parabolic distributions in an ellipsoidal shape 40 mm and 140 mm in diameters were examined. Target assemblies made of tungsten and tantalum plates 60 mm x 167 mm in area and in various thicknesses placed parallel with 1.5 mm in gap were studied. High velocity water around 10 m/s was required to flow in the gaps to remove the heat up to order of GW/m3 deposited in the target plates by the proton beam. Numerical calculation of heat conduction and thermal stress in the target plate was conducted to optimize the target thicknesses based on the heat deposition rate in the target calculated by the Monte-Carlo method. The thermal stress in the tantalum target in ISIS and the tungsten target in APT were estimated. The target thickness was designed based on the calculated stress in ISIS and APT. The averaged density of the designed target was discussed. (author)