Development of the unified cross-section set ADJ2000 for fast reactor analysis

not registered; Numata, Kazuyuki*; Sato, Wakaei*; Sugino, Kazuteru

In the core design of fast breeder reactors, it is very impotant to improve the prediction accuracy of nuclear characteristics from the viewpoint of both reducing cost and insuring reliability of plant. The most powerfull method to reflect the C/E (Calculation/Experiment) values obtained from critical experimental analysis on the design work is the cross-section adjustment technique which is to unify cross-section covariance, integral experimental and analytical errors and the sensitivity coefficients of various cores and parameters based on the Bayesian parameter-estimation theory. The adjusted cross-section set is called "a unified cross-section set" here, since it combines integral experimental information with differential nuclear data. The main features of ADJ2000 compared with the preceding unified cross-section sets which were also developed by JNC (the former PNC) are as follows: First, the basic cross-section set adjusted was generated from JENDL-3.2, which is the latest version of the evaluated library in Japan at present. Second, the adjusted nuclear parameters include the self-shielding factors which were newly introduced in the adjusted parameters so that the accuracy of the Doppler reactivity can be improved. Third, the covariance data of nuclear parameters used in the adjustment were derived from the JENDL-3.2 Covariance File which has been completed and released by the Japan Nuclear Data Committee lately. Fourth, the integral experimental data were widely extended to include various independent facilities such as FCA in Japan, MASURCA in France, BFS-2 in Russia, JOYO as a power reactor, small core experiments in Los Alamos, as well as a series of JUPITER experiments in ANL/ZPPR that was only one experimental database in the previous adjustment study. Fifth, the integral data used in the adjustment includes the burnup- and temperature-related characteristics which are very important for power fast reactors. Finally, the statistical chi-square ...