Application of sensitivity and uncertainty methodology to fast reactor integral experiment analysis

The first results are presented of a comprehensive application of the sensitivity theory developed for the FORSS code system to the analysis of fast reactor integral experiments. A variety of assemblies and performance parameters were studied to determine the nuclear data sensitivity as a function of nuclide, reaction type, and energy. Comprehensive libraries of energy-dependent sensitivity coefficients were developed. Uncertainties induced by nuclear data were quantified using preliminary energy-dependent relative covariance matrices evaluated with ENDF B-IV cross sections and processed for /sup 238/U(n,f), /sup 238/U(n,..gamma..), /sup 239/Pu(n,..gamma..), and /sup 239/Pu(anti ..nu..). Calculational results, cross-section covariances, and integral results and their covariances were used in a consistent fashion to improve uncertainty estimates . A first attempt was made to quantify specifications for new cross-section measurements required to satisfy specific design goals at minimum experimental cost. An analysis of several critical experiments indicated that design accuracy goals of 0.5% in k and 2% in the central /sup 238/U capture: /sup 239/Pu fission ratio (/sup 28/c//sup 49/f) ratio in mixed oxide liquid-metal fast breeder reactor cores are unlikely to be attained in the near future. this result assumes the nuclear data are based only on microscopic measurements, and the current cross-section measurement programmore » is not changed dramatically. Current estimates are 2.3% in k and 7.3% in central reaction ratio using only differential covariance information. Using the measurements in ZPR-6/7 for k and central /sup 28/c//sup 49/f in a cross-section adjustment scheme with assigned uncorrelated standard deviations of 1 and 2%, respectively, standard deviations of the same parameters were computed to be 0.7 and 1.8%. Results of integral experiments, therefore, are needed to improve uncertainty estimates.« less