Analysis of experimental series of plutonium nitrate in aqueous solution and their correlation coefficients

TL;DR

This paper analyzes 43 critical experiments involving plutonium nitrate solutions, focusing on correlation coefficients, sensitivity analysis, and the impact of experimental and nuclear data uncertainties, highlighting the importance of detailed data interpretation.

Contribution

It provides a comprehensive analysis of correlation coefficients in plutonium nitrate experiments, emphasizing the significance of modeling assumptions and sensitivity analysis for accurate criticality safety assessments.

Findings

Correlation coefficients often statistically insignificant

Agreement with DICE database for nuclear data correlations

Experimental uncertainty impacts correlation coefficient reliability

Abstract

In this work we performed a detailed analysis on the calculation of 43 critical experiments from 6 experimental series all describing plutonium nitrate in aqueous solution contained in metal spheres. The underlying experimental data is taken from the handbook of the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Working Group. We present our modeling assumptions which were derived from the interpretation of the experimental data and discuss the resulting sensitivity analysis. Although the experiments share some components, the derived correlation coefficients are for many cases statistically not significant. Comparing our findings for the correlation coefficients with available data from the DICE Database we find an agreement for the correlation coefficients due to nuclear data. We also compare our results for the correlation coefficients due to experimental uncertainty. Our findings indicate that for the reliable Determination of correlation coefficients a detailed study of the underlying experimental data, the modeling approach and assumptions, and the resulting sensitivity analysis seems to be inevitable.