A Point Detector Scoring Method Compatible with Monte Carlo Transport Calculations of Specularly Reflected Particles

In using a Monte Carlo transport code, particle fluxes are underestimated with a calculational model using specular reflection boundaries when a point detector estimator that scores only the direct contribution to the detector from a collision point within the model is used. This underestimation occurs because the contributions from collision points outside the calculational model are neglected. An additional scoring scheme is developed to compensate for the discrepancy; the new scheme is implemented to three-dimensional Monte Carlo transport code MORSE-GG. Validity of the method is shown by test calculations with ANISN and revised MORSE-GG.