Multi-group analysis of Minor Actinides transmutation in a Fusion Hybrid Reactor

Abstract

New nuclear technologies are currently being study to face High Level Waste treatment and disposal issues. Generally, GEN-IV fission Fast Reactors (FR) are considered the waste-burners of the future. In fact, a fast flux turns out to be the best choice for actinides irradiation in critical reactors because of favorable cross section conditions. Differently, Fusion Fission Hybrid Reactors (FFHR) are futuristic devices based on the combination of fusion and fission systems and could represent an alternative to FRs. In such systems, the choice spectrum of the neutron flux that irradiates HLW may be non-obvious due to some operational constraints which have to be considered. To design and optimize these systems as waste-burners, one should fully understand the transmutation dynamics occurring into the fission region. A multi-energy-group analysis by FISPACT-II code has been set to analyze the conversion processes in scenarios characterized by different neutron energy spectra and fluences. The results of this study show that, despite fast fluxes are characterized by better behaviors in terms of radiotoxicity treatment, the difficulties of reaching high reaction yields may require solutions involving moderators or broadened neutron fluxes to increase the reactions probabilities and, consequently, actinides mass conversion yield.

RFP-MSR Hybrid Reactor Model for Tritium Breeding and Actinides Transmutation †

“…Future analysis will also regard the actinide target irradiation in the thermal box. In fact, recent studies [26] showed that low-fluence thermal neutron irradiation on HLW may lead to interesting results for waste recycling in FFHR systems. On the other hand, LOMBT is only slightly affected by irradiation.…”