Monte Carlo Higher Modes Calculation based on the Extension of the Noise Propagation Matrix

Abstract

The Noise Propagation Matrix Method (NPMM) has been extended to get the higher mode solutions. Previous studies show that the NPMM can be used to compute the dominance ratio (DR) of a system. It is essentially the same as the Coarse Mesh Projection Method (CMPM), both of which use the Noise Propagation Matrix (NPM) to determine the DR, either after finishing the Monte Carlo simulation or on-the-fly during the simulation. Since only the fundamental fission source information is explicitly utilized while the higher mode information is implicitly contained in the statistical noises, the NPMM usually requires thousands of cycles to get an approximated estimation of the DR. In this study, the NPMM is extended by simulating the higher modes explicitly. In this way, smaller number of cycles is required to get an accurate estimation of the DR, and the higher mode solutions can be obtained at the same time with good accuracy and efficiency.