Creation of a Database of Uncertainties for ICSBEP Handbook and Tool for Covariance Generation

Abstract

The creation of a database of uncertainties for criticality experiment benchmarks is under construction and intended to be incorporated into a future version of the database for ICSBEP, DICE. As a first step, Section 2 and 3.1 data have been extracted from ICSBEP benchmark evaluations and homogenized in a manner that allows searching and trending uncertainties across evaluations. One of the primary objectives of building such a database is to facilitate creation of covariance matrices between experimental uncertainties, as often, only the diagonal term has been evaluated leading to cases being treated as independent during uncertainty analysis. This assumption does not reflect a best estimate. The database-features lower the effort required to create covariance’s, so analysts can focus on estimating whether uncertainties are shared between cases, rather than the mechanical aspects of uncertainty extraction and matrix generation. Now users can quickly create transparent estimates of covariance. Using the sheet an attempt has been made to read the evaluations and then provide an estimate of the covariance by estimating which uncertainty components are shared between cases. While it is difficult to evaluate the ‘correctness’ of the generated covariance’s, the paper has run the over 500 of LCT cases with experimental covariance, through a generalized least squares tool, TSURFER, both with experimental covariance’s and without and the results are analyzed. Further work is required in the area of testing the impact on real world applications.