Conceptual design of thorium based epithermal spectrum reactor

The concept of the epithermal spectrum nuclear core by using thorium fuel is proposed newly in order to maximize thorium breeding capability. By changing lattice size of fuel rod in the typical light water reactors, less moderation is possible and epithermal neutron spectra are achieved. In order to check the feasibility of the epithermal reactor, the fuel lattice analysis has been carried out by using the NEWT code and MCNP6 code including depletion calculation. Additional test for epithermal reactor is performed from a fast reactor by introducing a new fuel composition such as ThUZrHx. Due to small contents of hydrogen, the fast neutron spectrum is easily shifted to the epithermal region. Thorium epithermal core analysis is also carried out extending to 100 MWt power including some safety parameters such as void reactivity and Doppler coefficient.