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Science and Technology of Nuclear Installations
Volume 2008 (2008), Article ID 798901, 7 pages
Research Article

GRS Method for Uncertainty and Sensitivity Evaluation of Code Results and Applications

Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH, Forschungsinstitute, 85748 Garching, Germany

Received 8 May 2007; Accepted 14 February 2008

Academic Editor: Cesare Frepoli

Copyright © 2008 Horst Glaeser. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


During the recent years, an increasing interest in computational reactor safety analysis is to replace the conservative evaluation model calculations by best estimate calculations supplemented by uncertainty analysis of the code results. The evaluation of the margin to acceptance criteria, for example, the maximum fuel rod clad temperature, should be based on the upper limit of the calculated uncertainty range. Uncertainty analysis is needed if useful conclusions are to be obtained from “best estimate” thermal-hydraulic code calculations, otherwise single values of unknown accuracy would be presented for comparison with regulatory acceptance limits. Methods have been developed and presented to quantify the uncertainty of computer code results. The basic techniques proposed by GRS are presented together with applications to a large break loss of coolant accident on a reference reactor as well as on an experiment simulating containment behaviour.