Analysis of axial distribution of B4C and Pu sample worths in FCA assembly XVII-1

In order to improve the material sample worth analysis the spatial dependence of B4C and Pu sample worths was investigated in FCA assembly XVII-1 which was a typical MOX-fueled core. In the experiment the sample worths were obtained from the differences between reactivities with and without the samples. The analysis was carried out using several calculation models and their results were compared. Furthermore, the effect of hydrogen involved in the coating of DUO2 plates, the effect of the gap between cores, transport effect and mesh size effect were estimated. Then the calculated values were compared with the measured ones. In both cases of B4C and Pu the estimated values were in reasonably good agreement with the measured ones in the core region. However, agreement was not so good in the blanket region. (author)