Background Transmutation of Np, Am, and Cm minor actinides appears to be a key direction for reducing the long-term radiotoxicity of spent nuclear fuel from thermal and fast reactors. High specific heat emission of ~2.5 kW/kg makes Cm isotopes difficult to include in fast reactor fuel due to the features of fabrication. The solution may be the transmutation of Cm in specialized units. Aim To perform a computational study of Cm transmutation in the MSR‑B molten salt nuclear reactor for reducing the radiotoxicity of spent nuclear fuel. Materials and methods The object of the study is the fuel campaign of the MSR‑B reactor: 2400 MW(t), 73% LiF—27% BeF2 carrier salt, and CmF3 fuel component. The research method is numerical simulation in the MCU-MSR software developed by the National Research Center “Kurchatov Institute”. Calculation methods include simulation of radiation transfer in three-dimensional systems using the method of Monte Carlo and nuclide kinetics with quasi-continuous correction of material compositions. Results and discussion The concept of the reactor, its main technical parameters, and design features are presented. Calculations confirm the possibility of effective Cm transmutation. In contrast to Np and Am, high fission cross-sections of 243Cm, 245Cm, and 247Cm ensure a high rate of their transmutation without the accumulation of secondary long-lived nuclei. The reactor requires no additional Pu or other fissile isotopes introduced to the Cm transmutation cycle. The presence of light nuclei shifts the spectrum to the thermal region optimal for Cm transmutation. Homogeneous salt simplifies fuel composition control and fission product removal. The equilibrium content of key and all fuel isotopes in the fuel circuit is demonstrated to be reached within the first 3 and 15 years of reactor operation, respectively. Over 50 years of operation, ~39 t of Cm are loaded into the MSR‑B circuit: 95% is transmuted with < 1% (~1.9 t) remainder of secondary long-lived actinides. Conclusion A molten salt reactor based on LiF–BeF2 ensures highly efficient transmutation of Cm with minimal accumulation of secondary actinides. A qualitative analysis shows that one ~600 MW(t) MSR-Cm specialized reactor is sufficient to transmute the forecast amount of Cm accumulated by the Russian nuclear power industry until 2100.

Molten salt reactor for curium transmutation

期刊论文
发表日期：

2025年9月1日

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A. V. Lopatkin,
I. T. Tretyakov,
D. S. Klimenko

摘要

Background

Transmutation of Np, Am, and Cm minor actinides appears to be a key direction for reducing the long-term radiotoxicity of spent nuclear fuel from thermal and fast reactors. High specific heat emission of ~2.5 kW/kg makes Cm isotopes difficult to include in fast reactor fuel due to the features of fabrication. The solution may be the transmutation of Cm in specialized units.

Aim

To perform a computational study of Cm transmutation in the MSR‑B molten salt nuclear reactor for reducing the radiotoxicity of spent nuclear fuel.

Materials and methods

The object of the study is the fuel campaign of the MSR‑B reactor: 2400 MW(t), 73% LiF—27% BeF₂ carrier salt, and CmF₃ fuel component. The research method is numerical simulation in the MCU-MSR software developed by the National Research Center “Kurchatov Institute”. Calculation methods include simulation of radiation transfer in three-dimensional systems using the method of Monte Carlo and nuclide kinetics with quasi-continuous correction of material compositions.

Results and discussion

The concept of the reactor, its main technical parameters, and design features are presented. Calculations confirm the possibility of effective Cm transmutation. In contrast to Np and Am, high fission cross-sections of ²⁴³Cm, ²⁴⁵Cm, and ²⁴⁷Cm ensure a high rate of their transmutation without the accumulation of secondary long-lived nuclei. The reactor requires no additional Pu or other fissile isotopes introduced to the Cm transmutation cycle. The presence of light nuclei shifts the spectrum to the thermal region optimal for Cm transmutation. Homogeneous salt simplifies fuel composition control and fission product removal. The equilibrium content of key and all fuel isotopes in the fuel circuit is demonstrated to be reached within the first 3 and 15 years of reactor operation, respectively. Over 50 years of operation, ~39 t of Cm are loaded into the MSR‑B circuit: 95% is transmuted with < 1% (~1.9 t) remainder of secondary long-lived actinides.

Conclusion

A molten salt reactor based on LiF–BeF₂ ensures highly efficient transmutation of Cm with minimal accumulation of secondary actinides. A qualitative analysis shows that one ~600 MW(t) MSR-Cm specialized reactor is sufficient to transmute the forecast amount of Cm accumulated by the Russian nuclear power industry until 2100.