Molybdenum with MOX Nuclear Fuel to be Used for the Second Load of Generation IV ALLEGRO Nuclear Reactor Using the Monte Carlo Method

Abstract

Abstract: A new nuclear fuel consisting of 80% MOX and 20% molybdenum is proposed to be used in Gen IV reactors (ALLEGRO Reactor). The average temperature drop on the fuel (ATDF) decreased by about 153 °C with respect to the non-mixed MOX with a consequent decrease of the average temperature on the fuel-rod axis (ATFA) by 166.4 °C. This temperature reduction can be utilized to increase the coolant outlet temperature (T_out), thereby enhancing the efficiency of the thermodynamic cycle of the coolant (ETCC). The MALBRN computational system was used to address the neutronic problem using the Monte Carlo method (MCM) and the thermal-hydraulic problem using correlations available in the literature. A comparison of the new fuel with standard nuclear fuels, such as carbides (CFs) and nitrides (NFs), was conducted based on thermal properties. The new fuel exhibits an ATDF comparable to those of CFs and NFs. Moreover, the new fuel enables coolant outlet temperatures to reach high values (up to 1140.4 °C), facilitating advanced applications for generation IV reactors. As a result, a very high ETCC (up to 64.90%) can be achieved. However, this improvement comes at the cost of a higher plutonium content in the final fuel (26.84% compared to 20.35%).

Keywords: ALLEGRO and Gen IV reactors, Carbide and Nitride fuels, MOX fuel, Molybdenium, MALBRN computation system, Monte Carlo method.

PACS: 25.85.−w Fission reactions.