The analytical study of inventories and physicochemical configuration of spallation products produced in Lead-Bismuth Eutectic of Accelerator Driven System

摘要

Lead-Bismuth Eutectic (LBE) is used as a spallation neutron target and coolant material of Accelerator Driven System (ADS), and many kinds of elements are produced as spallation products via spallation reactions in LBE of ADS. It is important to evaluate the release and transport behavior of the spallation products in the LBE coolant system of ADS from the viewpoints of the radiological hazard both in the cases of normal operation and accident. The physicochemical configuration of the spallation products is essential to evaluate the release and transport behavior because the physical and chemical properties such as solubility in LBE and volatility depend on the configuration. The inventories and the physicochemical configuration of the spallation products produced in LBE have been investigated for an LBE loop to be installed in the ADS Target Test Facility (TEF-T) in the Japan Proton Accelerator Research Complex (J-PARC). The inventories of the spallation products in the LBE were estimated using the PHITS code based on the technical design specifications and the operation program of TEF-T. The physicochemical configuration of the spallation products in the LBE was calculated using the Thermo-Calc code under the conditions of the operation temperatures of LBE from 350 degrees C to 500 degrees C and the oxygen concentrations in LBE from 10 ppb to 10 ppm. From the results of the PHITS code evaluation, 18 elements were evaluated as the important elements from the viewpoint of these large inventories and the radiation hazards of their radionuclide. The results of the Thermo-Calc calculation showed the 8 elements of Rb, Tl, Tc, Os, Ir, Pt, Au and Hg were soluble in LBE under the all given conditions and any kinds of compound were not formed in LBE. It was suggested that the oxides of Ce, Sr, Zr and Y were stable as CeO2, SrO, ZrO2, Ce2O3 and Y2O3 in the LBE. The validity of these results was discussed compared with the previous experimental and theoretical work.