Analysis of criteria for transmutation as an effective method for removing hazardous radioactive waste

Background: As a key task of nuclear power industry, transmutation raises the problem of radiation equivalence and utilization of minor actinides (MAs). The conversion of MAs into fission products appears to be the best way to solve it.

Aim: To develop criteria for comparing the efficiency of transmutation in different reactor plants (RPs) without the deep analysis of nuclear power development scenarios and numerous assumptions regarding external parameters.

Materials and methods: The selected criteria included the absolute mass balance and number of fissions, as well as those taking into account the operation of the RP as part of nuclear power industry. Lists of unfavorable MAs such as long-lived high-level waste (LLHW) have been compiled for the developed transmutation efficiency methodology. The selected criteria and LLHW lists were validated by simulating the first campaign of a lead-cooled fast neutron reactor (FR) and a VVER-1200 water-water power reactor with the addition of MAs.

Results and discussion: We propose to normalize the amount of transmuted material to the thermal power in the core in order to adequately compare the transmutation efficiency of different reactors. This approach has revealed and confirmed the efficiency of transmutation in FRs, both homo- and heterogeneously loaded, to be significantly higher than that for VVER-1200 reactors. We recommend to determine the mass balance using the LLHW list including all MAs and ²³⁸ Pu.

Conclusion: To evaluate the transmutation efficiency by the selected RPs, we propose to use the criterion of the difference between the masses of loaded and unloaded actinides, as well as to normalize the amount of the transmuted material to the thermal power of the core.