Abstract: Background and Purpose: Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF) is a new type reactor. The neutron energy spectrum, an important parameter for TMSR-SF, needs to be measured, although the environment temperature is very high. The needed libraries for the measurement must be processed due to the special measurement environment. Therefore, the processes and the accuracy for the cross section library are important to the measurement result. Methods: Based on the recently released ENDF/B-VII.1 library, the process of using NJOY to obtain multigroup cross section needed by the neutron energy spectrum measurement of TMSR-SF at certain temperature is introduced. The relationship between multigroup cross section for two typical nuclear reactions and the temperature is analyzed. Homemade libraries at different temperatures are used in the neutron energy spectrum measurement. The difference of the results for neutron energy spectrum with different libraries is shown. Results: Analysis results indicate that the temperature will affect the cross sections of nuclear reactions, especially on the nuclide section of epithermal neutron with resonance peaks due to Doppler effect. The result of neutron energy spectrum measurement is influenced by the selected nuclear reaction. The result accords with the relevant physical laws. Conclusion: The homemade library in 873 K can be used in the neutron energy spectrum calculation for TMSR-SF.

Key words: ENDF/B-VII.1, Neutron energy spectrum, Multigroup nuclear cross section processing, Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF)