Analyses of experiments in the Joyo fast reactor using the ERANOS and JNC code systems

JOYO is an experimental fast reactor in Japan. JNC has analyzed some of the JOYO MK-I experiments using its own latest code system. On the other hand, the European analysis system ERANOS is under validation and was applied to an analysis of the JOYO experiments. The first step in this comparison was the common analysis of the JUPITER experiments, and had been reported in the PHYSOR2000 conference. This paper describes the analyses performed using the two code systems and subsequent intercomparisons of the results. One-region homogeneous core with blanket, JOYO MK-I (the first phase core of JOYO), has been considered. The calculated parameters are criticality (critical mass) and burnup reactivity coefficient. Further, sensitivity analyses for differences among nuclear data libraries have been performed in order to clarify the effect of library and to determine the effect of analytical method. The use of ERALIB1 adjusted library in ERANOS improves not only the results of the JUPITER core but also those of the burnup reactivity coefficient of JOYO MK-I core. However, it worsens the result of the criticality of JOYO MK-I core. There is a room for improvement concerning the criticality of small uranium-enriched cores like JOYO MK-I. On the burnup reactivity coefficient, the use of U-235 capture cross-section in JEF-2.2 and β_eff obtained by ERANOS improves the results in the JNC system. (author)