Victor Hugo Sanchez-Espinoza

On the Uncertainty and Sensitivity Analysis of Experiments With Supercritical Water With TRACE and SUSA

This study was performed at the Institute for Neutron Physics and Reactor Technology at Karlsruhe Institute of Technology and is addressed to establish the combined usage of the best-estimate code TRACE and the uncertainty and sensitivity analysis tool SUSA, for safety related investigations of current and future nuclear energy systems. In the frame of this paper the applicability to supercritical water related investigations is covered. Several Nusselt correlation for the heat transfer to supercritical water are available and have been evaluated in previous investigations but not one of them gave satisfying results. Hence, the consideration of uncertainty and sensitivity measures applied to the topic of heat transfer seems to be an appropriate way. In a first step a post-test analysis of an experiment was conducted. Results showed that with the help of uncertainty and sensitivity methods parameters which affect the results most could be identified. The most important parameter was of course the Nusselt correlation. In addition to the identification of important parameters, the experimental results were enveloped by the calculated results. That means, in the sense of safety related evaluation of designs for reactors operated with supercritical water, that key parameters (cladding temperature) can be calculated with a certain confidence.Copyright

Accelerating AZKIND Simulations of Light Water Nuclear Reactor Cores Using PARALUTION on GPU

This paper presents the results of the accelerated solution of the linear algebraic system Av = b arising from a nodal finite element method implemented in the neutron diffusion code AZKIND to solve 3D problems. The numerical solution of full nuclear reactor cores with AZKIND implies the generation of large sparse algebraic systems that produce bottle-necks in the iterative solution. Aiming to alleviate the overload of the algorithm, an acceleration technique has to be implemented. Consequently, a Fortran plug-in of the open source linear algebra PARALUTION library (C ++) was integrated into the AZKIND source code (Fortran 95). This implementation allows AZKIND to use GPUs as well as CPUs, threading into the GPU thousands of arithmetic operations for parallel processing. Selected examples of preliminary investigations performed for a cluster of nuclear fuel assemblies are presented and the obtained results are discussed in this paper.