Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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AN ASSESSMENT OF UNCERTAINTY ON A LOFT L2-5 LBLOCA PCT BASED ON THE ACE-RSM APPROACH: COMPLEMENTARY WORK FOR THE OECD BEMUSE PHASE-III PROGRAM

  • Ahn, Kwang-Il (Korea Atomic Energy Research Institute) ;
  • Chung, Bub-Dong (Korea Atomic Energy Research Institute) ;
  • Lee, John C. (University of Michigan)
  • Received : 2009.08.31
  • Accepted : 2009.11.26
  • Published : 2010.04.30
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Abstract

As pointed out in the OECD BEMUSE Program, when a high computation time is taken to obtain the relevant output values of a complex physical model (or code), the number of statistical samples that must be evaluated through it is a critical factor for the sampling-based uncertainty analysis. Two alternative methods have been utilized to avoid the problem associated with the size of these statistical samples: one is based on Wilks' formula, which is based on simple random sampling, and the other is based on the conventional nonlinear regression approach. While both approaches provide a useful means for drawing conclusions on the resultant uncertainty with a limited number of code runs, there are also some unique corresponding limitations. For example, a conclusion based on the Wilks' formula can be highly affected by the sampled values themselves, while the conventional regression approach requires an a priori estimate on the functional forms of a regression model. The main objective of this paper is to assess the feasibility of the ACE-RSM approach as a complementary method to the Wilks' formula and the conventional regression-based uncertainty analysis. This feasibility was assessed through a practical application of the ACE-RSM approach to the LOFT L2-5 LBLOCA PCT uncertainty analysis, which was implemented as a part of the OECD BEMUSE Phase III program.

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References

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