Wilks' formula applied to computational tools: A practical discussion and verification. (November 2019)

• Record Type: Journal Article
• Authors: Porter, N.W.
• Is Part Of: Annals of nuclear energy. Volume 133(2019)
• Page Start: 129
• Page End: 137
• Publication Date: 2019-11
• Subjects: Wilks' formula -- Uncertainty analysis -- Order statistics -- Best estimate -- Safety limits; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2019.05.012
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Wilks' method for setting tolerance limits is derived and verified. Higher order Wilks analysis increases the accuracy and precision of the predicted tolerance. In most practical applications, higher order analysis is unnecessary. Wilks' method is applied to the Dittus-Boelter equation. Abstract: Wilks' non-parametric method for setting tolerance limits using order statistics has recently become popular in the nuclear industry. The method allows analysts to predict a desired tolerance limit with some confidence that the estimate is conservative. The method is popular because it is simple and fits well into established regulatory frameworks. A critical analysis of the underlying statistics is presented in this work, including a derivation, analytical and statistical verification, and a broad discussion. Possible impacts of the underlying assumptions for application to computational tools are discussed. An in-depth discussion of the order statistic rank used in Wilks' formula is provided, including when it might be necessary to use a higher rank estimate.