Proposal of integral critical experiments for low-moderated mox fissile media
I. DUHAMEL ( IRSN/DSU/SEC) - E. GIRAULD (CEA/SRNC, CEA Valduc) - C. VENARD (CEA/SPRC/LECy, CEA Cadarache)
2005 NCSD Topical meeting - Knoxville, Tenessee, USA - 19th-22th september 2005
The assessment of the available benchmarks, performed by the OECD/NEA Working Party on Nuclear Criticality Safety Expert Group on Experimental Needs, has highlighted the need of additional experiments dealing with low-moderated MOX powders, which are mainly encountered in MOX fuel manufacturing. For the different configurations assessed in manufactory safety report, the neutron flux varies between the fast and the intermediate energy range. As the fissile media heterogeneity has not a great impact in such spectrum, IRSN has studied the possibility of performing integral critical experiments with low water‑moderated MOX fuel rods assemblies. The proposal consists of different configurations dealing with various tight triangular lattices pitches, which would be assembled in two French criticality facilities. Design has been optimized taking into account the feasibility of the experiment, the possibility of using the existing materials and equipment, the fuel fabrication cost and the representativity of the experiments regarding powders encountered in MOX fuel manufacturing. Conclusions are based on the comparisons of spectral, balance and sensitivity data between, on one hand, the proposed experiments and, on the other hand, application configurations involving MOX powders dealing with different PuO2 and water contents. They point out that the proposed experiments provide a good representation of the application configurations, especially for water reflected configurations with 10 to 30 % content of reactor grade plutonium and 3 to 5 % water concentration.