Investigation of thorium utilization in accelerator driven systems

This article deals with the idea of using accelerator driven systems for thorium transmutation into the fissile material, which can be utilized in the accelerator driven systems and in thermal nuclear reactors. Thorium occurs on the Earth only in fertile isotope Th-232. It can be converted to fissile isotope U-233 by neutron capture and subsequent beta decay. The experimental part handles the data that were acquired by irradiation of four thorium samples in the field of secondary neutrons inside the QUINTA spallation set-up, which was irradiated by 660 MeV protons. Reaction rates for the different products were estimated using gamma-ray spectroscopy and activation techniques. Furthermore, Pa-233 production rates were also determined in all experimental samples. Pa-233 and fission production rates were calculated in all experimental samples using the MCNPX transport code and evaluated nuclear data for high-energy reactions. The experimental results are of a great importance for the future investigation of thorium in the accelerator driven system concept, validation of Monte Carlo-based calculation codes and validation of high-energy nuclear models.