Reactor core transient analysis of an innovative high-level nuclear waste transmuter with metal fuel

For the sustainable development of nuclear energy, reducing high-level nuclear wastes in spent fuels discharged from commercial nuclear power plants is very important. Partitioning and transmutation of minor actinides from these spent fuels are critical for the effective disposal of high-level wastes. However, transmutation in current operational reactors is not efficient and brings some safety problems. Therefore, a dedicated accelerator-driven subcritical transmuter named highly efficient industrial transmuter (HEIT) was newly proposed to solve the problems. This system utilizes the uranium-free metallic dispersion fuel and is of high power density. This paper focuses on the transient analysis of HEIT to prove that it is feasible for the future nuclear industry. Temperatures, cladding stresses, and cumulative creep damage fractions are analyzed. Furthermore, the burnup dependence is also investigated. Three typical transients including the unprotected loss of flow, the beam overpower (BOP), and the unprotected transient overpower are evaluated. Numerical results conclude that in the reactivity insertion transient and the BOP transient, this new system exhibits excellently in safety. However, the shut-down system is required in flow loss case which lasts more than half an hour. The safety margin changes with core depletion. For unprotected loss of flow, the end of lifetime case is the most important one to care. While for BOP and unprotected transient overpower, both the beginning and end of lifetime should be accommodated. The conclusions will be useful in the future design of HEIT and similar systems.