Study on Calculation of Regulated Neutron Spectrum Based on Moderator with Multi-dimensional Features

Neutron transport simulation is one of the key techniques for calculating the regulated neutron spectrum, which is extremely accurate but comes with a significant time loss and is difficult to achieve convergence when there is deep penetration. Accurate regulation of the neutron spectrum is essential for research on experimental neutronics. In this study, a fast way to compute the regulated neutron spectrum using a moderator with multi-dimensional features was developed. The response matrix with different dimensions was generated for each moderator after it first created a moderator database by classifying common shielding materials based on various dimensions (such as shape, size, substance, etc.). Finally, neutron transport modeling enabled the speedy and precise estimation of regulated neutron spectrum via matrix transformation. The results demonstrated that the mean square error (MSE) of the normalized regulated neutron spectra computed using the Monte Carlo approach and the proposed technique were able to reach the order of 10 −6 . The anticipated method was confirmed by equating the results with those of the Monte Carlo method under a regulation system consisting of moderators of different dimensions. Furthermore, the MSE of the regulated neutron spectrum in the case of deep penetration of the simplified thermal reactor TRIGA of the two methods in the convergent energy domain could also reach the order of 10 −6 , and in the divergent domain, the suggested method in this study was able to give a heuristic neutron spectrum.