  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.
