New calculational model for self-powered neutron detector based on Monte Carlo simulation

摘要

A new calculational model of detector sensitivity, which is defined as the ratio of electric current to neutron flux, for self-powered neutron detector (SPND) is presented in this paper. Since Warren developed a sensitivity calculation model based on a multi-step analytic approach in 1972, there have been a lot of researches aimed at improving the accuracy of his model by partially employing Monte Carlo (MC) simulations in some of the calculation steps. However, there still exist assumptions such as mono-energy neutron in those models which could increase the uncertainty of the calculated detector sensitivity. In this paper, a new model which overcomes those limitations is developed by adopting the MC method more thoroughly and thereby reducing the number of calculation steps. The verification of the new method has been performed by comparing the results against the ones from the existing methods and measured data. A detailed analysis of SPND depletion by ORIGEN-S and BETA-S codes has shown that the proposed model can predict accurately the measured depletion data in a commercial pressurized water reactor (PWR) plant.