High-resolution rapid calculation method of neutron spectrum based on energy response

Conventional neutron spectrum calculation methods are difficult to achieve both high resolution and high efficiency. This paper presents a high-resolution rapid calculation method of neutron spectrum. This method processes nuclear data library to generate high-resolution energy transfer probability matrices for various nuclides. The neutron spectrum of a specific region is rapidly calculated by the direct response between the initial spectrum and the energy transfer probability matrices. This method is capable of the complex geometry and material compositions in localized regions, enabling rapid calculations of neutron spectrum with high resolution. Verification with the Monte Carlo results under different geometry and material compositions demonstrates the precision of this method is comparable to that of Monte Carlo simulation. In addition, the application of this method is demonstrated through neutron spectrum calculations of isotope production targets in HFIR, and the stability of the method is proved in dealing with material perturbations.