Print Email Facebook Twitter A zero-variance based scheme for Monte Carlo criticality simulations Title A zero-variance based scheme for Monte Carlo criticality simulations Author Christoforou, S. Contributor Van der Hagen, T.H.J.J. (promotor) Hoogenboom, J.E. (promotor) Faculty Applied Sciences Department Radiation, Radionuclides & Reactors Date 2010-10-11 Abstract The ability of the Monte Carlo method to solve particle transport problems by simulating the particle behaviour makes it a very useful technique in nuclear reactor physics. However, the statistical nature of Monte Carlo implies that there will always be a variance associated with the estimate obtained, making the reduction of this variance, without a corresponding increase in calculation time, one of the main targets of research in Monte Carlo. A zero-variance scheme for a criticality calculation is devised in this thesis. It is shown that, when biasing the transport kernels by the adjoint function, it is possible to reach an estimate with zero variance. Using a simplified model, it was proven that the reduction of variance of the estimate obtained from a single neutron generation is only dictated by computational, and not theoretical, limits. However, although zero variance cannot be obtained in a criticality calculation in practice, a reduction in variance can be achieved, even when using approximate adjoint functions. The scheme was implemented in an own code as well as in the commercial MCNP5 code and tested in practical Monte Carlo reactor core calculations. The results verified a reduction in the variance, as well as no adverse effects in the convergence of the neutron source distribution. An appropriate increase in the efficiency of the calculation can be achieved when the implementation of the scheme in the code is optimised. Subject Monte Carlobiasingadjointcriticality To reference this document use: http://resolver.tudelft.nl/uuid:8799a094-5a09-4670-853a-4bd1626fce74 ISBN 9789609322478 Part of collection Institutional Repository Document type doctoral thesis Rights (c) 2010 Christoforou, S. Files PDF PhD_thesis_-_Christoforou.pdf 1.11 MB Close viewer /islandora/object/uuid:8799a094-5a09-4670-853a-4bd1626fce74/datastream/OBJ/view