Characteristics of Minor Actinides in Advanced Light Water Reactors

Abstract

The study of the neutronic safety parameters in reactors is very important where it provides a guide for future study in reactor design and reactor fuel. Also, it is regarded as the basic step for reactor waste transmutation.There are three main critical reactor facilities of the CEA cadarache. These reactor facilities are EOLE, MINERVE and MASURCA. The MINERVE reactor is used within the frame work of what is known as OSMOSE project. The OSMOSE program aims at improving neutronic predictions of advanced nuclear fuels through measurements in the MINERVE reactor on samples containing separated actinides. In the present work, The reactivity worth of OSMOSE samples have been calculated using the most recent Monte Carlo N Transport code MCNPX using the most recent nuclear cross-section data library ENDF/B-VII. The calculations are applied to the three core configurations R1-UO2, R2-UO2 and R1-MOX. The present work is performed to improve and /or measure the degree of validity of the previous obtained results of the REBUS and DRAGON codes.Additionally, the validity of the nuclear cross-section data library ENDF/B-VII for minor actinides. Also, our study is extended to include the experimental results for the sake of comparison. The obtained results from the present work showed a good agreement with the experimental results within a relative difference less than ± 8.3 % for the reactivity worth values for the three core configurations. Moreover, some of the basic neutroinc parameters that characterized MINERVE reactor in different core configurations R1-UO2, R2-UO2 and R1-MOX are calculated and discussed. These parameters are the neutron spectrum, the total, fast and thermal flux for both radial and axial distributions for the three core configurations. Additionally these neutronic parameters are calculated and analyzed for two predicted models “Homogeneous and Heterogeneous” which containdifferent concentration and distribution for two of the most important long-lived isotopes of minor actinides. The two studied isotopes of the minor actinides were 234Am and 247Cm. The results of the two predicted models were compared to that of one of the reference core configuration R1-UO2. As a result of comparison between the results of the two models and that of the reference core, the Homogeneous model showed good results and is regarded as a good preliminary configuration for the transmutation of the two important isotopes 234Am and 247Cm.