Interrelating Differential and Integral Nuclear Data

The adjustment of differential data can improve the agreement between calculation and experiment of integral quantities, but the adjustment process also introduces a posteriori correlations among the data that were not part of the a priori assumptions. In a forward calculation of integral parameters using adjusted differential data, the a posteriori correlations in general reduce the estimated uncertainty since the linear independence among differential data is reduced but the correlations inhibit the use of integral data to improve individual pieces of differential data. The adjusted data are validated for the calculation of integral parameters similar to those used in the adjustment. The physical interpretation of data adjustments is illustrated using a simple model to analyze bare homogeneous critical assemblies.