Design of Experiments for Screening

The aim of this paper is to review methods of designing screening experiments, ranging from designs originally developed for physical experiments to those especially tailored to experiments on numerical models. The strengths and weaknesses of the various designs for screening variables in numerical models are discussed. First, classes of factorial designs for experiments to estimate main effects and interactions through a linear statistical model are described, specifically regular and nonregular fractional factorial designs, supersaturated designs and systematic fractional replicate designs. Generic issues of aliasing, bias and cancellation of factorial effects are discussed. Second, group screening experiments are considered including factorial group screening and sequential bifurcation. Third, random sampling plans are discussed including Latin hypercube sampling and sampling plans to estimate elementary effects. Fourth, a variety of modelling methods commonly employed with screening designs are briefly described. Finally, a novel study demonstrates six screening methods on two frequently-used exemplars, and their performances are compared

A Bayesian framework for quantifying the uncertainty of physical models integrated into thermal-hydraulic computer codes

International audienc

A Bayesian approach for quantifying the uncertainty of physical models integrated into computer codes

International audienc

Méthodes statistiques pour la quantification inverse des incertitudes en thermohydraulique

International audienc

Development of good practice guidance for quantification of thermal-hydraulic code model input uncertainty

International audienceTaking into account uncertainties is a key issue in nuclear power plant safety analysis using best estimate plus uncertainty methodologies. It involves two main types of treatment depending on the variables of interest: input parameters or system response quantity. The OECD/NEA PREMIUM project devoted to the first type of variables has shown that inverse methods for input uncertainty quantification can exhibit strong user-effect. One of the main reasons was the lack of a clear guidance to perform a reliable analysis. This work is precisely devoted to the development of a first good practice guidance document for quantification of thermal-hydraulic code model input uncertainty. The developments have been done in the framework of the OECD/NEA SAPIUM project (January 2017-September 2019). This paper provides a summary of the main project outcome. Recommendations and open issues for future developments are also given

SAPIUM a systematic approach for input uncertainty quantification

International audienceUncertainty assessment is a key step in nuclear applications to ensure that a system cannot move towards unsafe conditions. This topic has already been addressed by several OECD/NEA projects such as UMS or BEMUSE. However, if uncertainty propagation methods have now become mature for industrial applications, the input uncertainties quantification on the physical models still requires further investigations. It is precisely in this context that the SAPIUM project has been proposed in order to reduce as much as possible (or at least better understand) the user-effect observed in the previous PREMIUM activity that was a first attempt to analyze available methods to handle this issue. The underlying idea of the proposed work is not to focus on method benchmarking but on the construction of a clear and shared systematic approach for input uncertainty quantification as it is already addressed in industries and RandD for related topics. The main outcome of the project is a first good practices document that can be exploited for safety study in order to increase the agreement among experts on recommended practices as well as on remaining open issues for further developments. End users are therefore the developers and the users of BEPU methodologies, as well as the organizations in charge of evaluating them. Since it is an on-going activity, this paper describes the general content of the SAPIUM activity. All the details of the contributions will be available in the final document that will be issued in 2019