Abstract
We study fission source sampling methods suitable for the iterative way of solving coupled Monte Carlo neutronics problems. Specifically, we address the question as to how the initial Monte Carlo fission source should be optimally sampled at the beginning of each iteration step. We compare numerically two approaches of sampling the initial fission source; the tested techniques are derived from well-known methods for iterating the neutron flux in coupled simulations. The first technique samples the initial fission source using the source from the previous iteration step, while the other technique uses a combination of all previous steps for this purpose. We observe that the previous-step approach performs the best.
Abstract
Wir untersuchen das Sampeln der Neutronenspaltquelle und entsprechende Sampling-Methoden, welche für das iterative Lösen gekoppelter Monte-Carlo-Neutronikprobleme geeignet sind. Insbesondere widmen wir uns der Frage, wie die anfängliche Monte-Carlo-Spaltquelle zu Beginn eines jeden neuen Iterationsschrittes optimal gesampelt werden sollte. Numerisch vergleichen wir zwei Vorgehensweisen, die Anfangsspaltquelle zu sampeln; die getesteten Verfahren sind abgeleitet von zwei allgemein bekannten Methoden zur Iteration des Neutronenflusses in gekoppelten Simulationen. Das erste Verfahren sampelt die initiale Spaltquelle auf der Grundlage des vorigen Iterationsschrittes, wohingegen in dem zweiten Verfahren eine Kombination aus allen vorausgegangenen Iterationsschritten gebildet wird. Wir beobachten, dass der Ansatz, die Spaltquelle aus dem vorherigen Iterationsschritt abzuleiten, am besten funktioniert.
Acknowledgements
The simulations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at PDC Center for High Performance Computing at KTH, Royal Institute of Technology.
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