Sensitivity analyses of a simulation model for estimating Fiber-Induced sump screen and core failure rates

David Morton, Bruce Letellier, Jeremy Tejada, David Johnson, Zahra Mohaghegh, Ernie Kee, Vera Moiseytseva, Seyed Reihani, Alexander Zolan

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Output from a high-order simulation model with random inputs may be difficult to fully evaluate absent an understanding of sensitivity to the inputs. We describe, and apply, a sensitivity analysis procedure to a large-scale computer simulation model of the processes associated with Nuclear Regulatory Commission (NRC) Generic Safety Issue (GSI) 191. Our GSI-191 simulation model has a number of distinguishing features: (i) The model is large in scale in that it has a high-dimensional vector of inputs; (ii) some model inputs are governed by probability distributions; (iii) a key model output is the probability of system failure-a rare event; (iv) the model's outputs require estimation by Monte Carlo sampling, including the use of variance reduction techniques; (v) it is computationally expensive to obtain precise estimates of the failure probability; (vi) we seek to propagate key uncertainties on model inputs to obtain distributional characteristics of the model's outputs; and, (vii) the overall model involves a loose coupling between a physics-based stochastic simulation sub-model and a logic-based Probabilistic Risk Assessment (PRA) sub-model via multiple initiating events. Our proposal is guided by the need to have a practical approach to sensitivity analysis for a computer simulation model with these characteristics. We use common random numbers to reduce variability and smooth output analysis; we assess differences between two model configurations; and, we properly characterize both sampling error and the effect of uncertainties on input parameters. We show selected results of studies for sensitivities to parameters used in the South Texas Project Electric Generating Station (STP) GSI-191 risk-informed resolution project.

Original languageEnglish (US)
Title of host publicationNuclear Education, Public Acceptance and Related Issues; Instrumentation and Controls (I and C); Fusion Engineering; Beyond Design Basis Events
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791845967
StatePublished - 2014
Event2014 22nd International Conference on Nuclear Engineering, ICONE 2014 - Prague, Czech Republic
Duration: Jul 7 2014Jul 11 2014

Publication series

NameInternational Conference on Nuclear Engineering, Proceedings, ICONE


Other2014 22nd International Conference on Nuclear Engineering, ICONE 2014
Country/TerritoryCzech Republic

ASJC Scopus subject areas

  • Nuclear Energy and Engineering


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