Improvement of Correlated Sampling Monte Carlo Methods for Reactivity Calculations

Abstract

Two correlated Monte Carlo methods, the similar flight path and the identical flight path methods, have been improved to evaluate up to the second order change of the reactivity perturbation. Secondary fission neutrons produced by neutrons having passed through perturbed regions in both unperturbed and perturbed systems are followed in a way to have a strong correlation between secondary neutrons in both the systems. These techniques are incorporated into the general purpose Monte Carlo code MORSE, so as to be able to estimate also the statistical error of the calculated reactivity change.The control rod worths measured in the FCA V-3 assembly are analyzed with the present techniques, which are shown to predict the measured values within the standard deviations. The identical flight path method has revealed itself more useful than the similar flight path method for the analysis of the control rod worth.

Depletion calculations based on perturbations. Application to the study of a REP-like assembly at beginning of cycle with TRIPOLI-4®

“…This scheme mimics the source convergence step in the perturbed scheme without inducing any specific systematic error (Favorite, 2009;He and Su, 2010;Su and He, 2010;Nakagawa and Asaoka, 2010).…”

Perturbation based Monte Carlo criticality search in density, enrichment and concentration

“…There are several kinds of Monte Carlo perturbation methods, such as differential operator sampling method (Rief, 1994), correlated sampling method (Jerome and Ely M, 1969;Nakagawa and Asaoka, 1978;Kitada et al, 1996), adjoint weighted sampling method (Kiedrowski et al, 2011;Shim and Kim, 2011), and so on. Unfortunately, not all these methods can be used for criticality search calculation.…”

Exact Monte Carlo calculation method for K-eigenvalue change using perturbation source method

“…The authors of [1] presented a thorough chronological review of the development of Monte Carlo perturbation methods for radiation transport calculations. According to the review, the correlated sampling method [5,7,10,12], differential operator sampling method [7,9,11,12], and adjoint-based perturbation method [13,14] are regarded as the primary perturbation calculation methods.…”