Uncertainty Analysis of Benchmark Experiments Using MCBEND

Abstract

Differences between measurement and calculation for shielding benchmark experiments can arise from uncertainties in a number of areas including nuclear data, radiation transport modelling, source specification, geometry modelling, measurement, and calculation statistics. In order to understand the significance of these differences, detailed sensitivity analysis of these various uncertainties is required. This is of particular importance when considering the requirements for nuclear data improvements aimed at providing better agreement between calculation and measurement. As part of a programme of validation activity associated with the international JEFF data project, the Monte Carlo code MCBEND has been used to analyse a range of benchmark experiments using JEF-2.2 based nuclear data together with modern dosimetry data. This paper describes the detailed uncertainty analyses that have been performed for the following Winfrith material benchmark experiments: graphite, water, iron, graphite/ steel and steel/water. Conclusions are reported and compared with calculations using other nuclear data libraries. In addition, the effect that nuclear data uncertainties have on the calculated results is discussed by making use of the data adjustment code DATAK. Requirements for further nuclear data evaluation arising from this work are identified.