Browsing by Author "Taavitsainen, Aapo"
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Item CFENSS-SRS method for the uncertainty analysis of nuclear fuel and neutronics(2016-06-14) Taavitsainen, Aapo; Vanhanen, Risto; Perustieteiden korkeakoulu; Tuomisto, FilipStatistical uncertainty analysis has received much attention in the past decade. The impacts of both nuclear fuel and nuclear data uncertainties have been studied separately but not as a coupled system. The main research question of this Thesis was to confirm whether the uncertainties of fuel behaviour parameters and the nuclear data can be propagated separately. The secondary goals included comparing various statistical perturbation methods. The computations were performed close to the framework of the OECD/NEA UAM-LWR TMI-1 Pressurized Water Reactor benchmark, and more specifically, its pin cell exercise. A novel CFENSS-SRS (Coupled Fuel Behaviour and Neutronics Stochastic Sampling with Simple Random Sampling) method is presented for the combined uncertainty analysis of nuclear fuel behaviour and neutronics. The method applies the statistical uncertainty analysis to univariate nuclear fuel parameters and correlated neutron cross sections. Truncated normal distribution is used as the objective distribution for drawing samples based on the Principle of Maximum Entropy. Due to practical difficulties in employing the distribution, the distribution parameters are approximated for the nuclear fuel parameters while a normal distribution is applied for the neutron cross sections. Negative values of inherently positive parameters are re-sampled to avoid distorting the distribution to a great extent. The results support the hypothesis that the nuclear fuel parameters and the nuclear data can truly be treated as independent sources of uncertainty. Additionally, it was revealed that the details of the perturbation methodology, such as using relative covariance matrices rather than absolute ones, have a much smaller impact on the output uncertainty than neglecting some of the uncertainty data.Item Design, fabrication and characterization of transmon circuits(2015-01-26) Taavitsainen, Aapo; Paraoanu, Sorin; Perustieteiden korkeakoulu; Pekola, Jukka
