Neutronics analyses of natural uranium fueled, light water cooled, heavy water moderated and graphite reflected nuclear reactors

The work presented in this paper was conducted to validate the computer codes such as WIMS-D/4 and CITATION for the criticality analyses of natural uranium fueled, light water cooled, heavy water moderated and graphite reflected reactors such as National Experimental Reactor (NRX) and Canadian Indian Reactor (CIR). These codes are then used to search a proliferation resistant reactor core. It was found that the replacement of light water coolant with heavy water and with increased moderation, the core can be operated at a power level of less than half as compared to the power level of NRX/CIR but the neutron flux will remain unaffected. This core will be smaller in size and therefore there will be savings in required quantities of D2O, graphite and fuel. It will produce much less plutonium with higher concentration of 240Pu, if the burnup is more than 2800 MWD/T. Furthermore, it was found that the void coefficient of the coolant will be less positive and therefore the system will be more safe as compared to original NRX/CIR design.