Conceptual design and feasibility analysis of a heat pipe cooled cermet fuel space nuclear reactor for mars surface application

The compact, safe, light-weight and highly reliable Space Nuclear Reactor (SNR) with heat pipe cooling is an excellent candidate for the potential needs of Mars surface applications. This work proposed a heat pipe reactor concept design which can provide 1 MWth power for more than 8 years. Reactivity control is accomplished by 6 rotating control drums. Cermet fuel with dispersion granules characteristics adopted in this design is processed into prismatic-type tube-in-duct (TID) and composed of Mo-14 wt%Re matrix and highly enriched uranium nitride (UN) granules. Both heterogeneous and homogeneous models of Cermet fuel are evaluated by OpenMC code, indicating an extreme weak resonance self-shielding effect. Neutronics characteristics such as the effective multiplication factor, burnup depth, fuel temperature coefficient, neutron spectrum, reactivity control, neutron flux and power distribution are obtained. Drum stuck accidents and submersion criticality accidents are also analyzed. The designed reactor achieves a shutdown depth of −1521 pcm in the worst launch or reentry accident scenario considered without relying on the reactivity control device. The arrangement forms and content of Spectral Shift Absorber (SSAs) that affect the safety worth are also analyzed. Furthermore, thermal analysis is performed by Fluent and the maximum temperature is lower than 1570K during normal operation. The maximum temperature reaches 1805K and core has sufficient margin to respond to a single point failure of the heat pipe. Overall, the scheme preliminarily satisfies neutronics, thermal and safety requirements.