Development of the unified cross-section set ADJ2000R for fast reactor analysis

Hazama, Taira ; Chiba, Go; Numata, Kazuyuki*; Sato, Wakaei*

ADJ2000R, the revised version of unified cross-section set ADJ2000, was developed. In ADJ2000R the error originated from JAERI FAST SET JFS-3-J3.2 is completely removed, which was not the case in ADJ2000. In the cross-section adjustment procedure, the error of JFS was completely removed from C/E (Calculation / Experiment) values and accordingly a different method was employed in evaluating analytical errors. Thereby degree of cross-section adjustment is largely different from that in ADJ2000, while change of C/E values by the adjustment are not affected. As a performance test, ADJ2000R was applied to a design analysis of 600MWe sodium cooled MOX fueled reactor. A drastic improvement was found in Doppler reactivity that was underestimated by about 10 % in ADJ2000 due to the error of JFS-3-J3.2. Differences from those with the original cross-section set are within a few percent except that burn up reactivity loss is 6% smaller. Design uncertainties are as small as those with ADJ2000 and are much reduced than those with the original cross-section set or the E/C bias method. ADJ2000R unified cross-section set has ability to predict accurately the various core characteristics of fast reactors from large cores to small cores, and from critical experiments to power reactors. ADJ2000R is open to the public, and is to be utilized in the feasibility study of future fast reactors.