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Ueki, Taro
Nuclear Science and Engineering, 194(6), p.422 - 432, 2020/06
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)In Monte Carlo criticality calculation, the convergence-in-distribution check of the sample mean of tallies can be approached in terms of the influence range of autocorrelation. In this context, it is necessary to evaluate the attenuation of autocorrelation coefficients over lags. However, in just one replica of calculation, it is difficult to accurately estimate small ACCs at large lags because of the comparability with statistical uncertainty. This paper proposes a method to overcome such an issue. Its essential component is the transformation of a standardized time series of tallies so that the resulting series asymptotically converges in distribution to Brownian motion. The convergence-in-distribution check is constructed based on the independent increment property of Brownian motion. The judgment criterion is set by way of the spectral analysis of fractional Brownian motion. Numerical results are demonstrated for extreme and standard types of criticality calculation.
Ueki, Taro
no journal, ,
It is often the case in Monte Carlo criticality calculation that the correlation over fission source generations makes statistical errors underestimated. To cope with this issue, the standard deviation estimation method of sample mean is under development using orthonormally weighted standardized time series. In this presentation, promising numerical results are shown for PWR initial core and uranium-concrete debris.
