Investigation of the required thickness of thorium spent fuel lead transport cask depending on different fuel burnups and cooling times

Thorium fuels have attracted researcher’s attention due to the reduction of uranium deposits in the world, more abundances than uranium, and the ability to be breeding in thermal and fast reactors. This study aimed to investigate the radiation safety and the amount of necessary shielding for the transportation of spent thorium fuel in the Tehran Research Reactor. The ORIGEN and MCNPX computational codes were used to calculate the gamma spectra of the spent fuel and the fuel dose rates loaded within the lead cask. The results of the calculations showed that compared to uranium fuels used in the Tehran Research Reactor, more cooling times are needed before the thorium spent fuel transport by the lead cask. In addition, the thickness of the cask required for the transport of the spent thorium fuel is greater than uranium fuel.