Critical Experiments that Simulated Damp MOX Powders - Do They Meet the Need?

The OECD Nuclear Energy Agency (NEA) Working Party on Nuclear Criticality Safety (WPNCS) identified the MOX fuel manufacturing process as an area in which there is a need for additional integral benchmark data. The specific need focused on damp MOX powders. The WPNCS was ultimately asked by the NEA Nuclear Science Committee (NSC) to provide the framework for the selection and performance of new experiments that fill the identified need. A set of criteria was established to enable uniform comparison of experimental proposals with generic MOX application data. Criteria were established for five general characteristics: (1) neutronic parameters, (2) type of experiments, (3) financial aspects, (4) schedule, and (5) other considerations. Proposals were judged most importantly on their ability to match the neutronic parameters of predetermined MOX applications. The neutronic parameters that formed the basis for comparison included core average values (not local values) for flux, fission and capture rate; detailed balance data (fission and capture) for the main isotopes (Actinides, H and O); sensitivity coefficients to important nuclear reactions (fission, capture, elastic and inelastic scatter, nu-bar, mu-bar) for all uranium and plutonium isotopes, hydrogen, and oxygen; sensitivity profiles to the main nuclear reactions for uranium and plutonium isotopes; energy of average lethargy causing fission; and the average fission group energy. The focus of this paper is on the definition of the need; the neutronics criteria established to assess which, if any, of three proposed MOX experimental programs best meet the need; and the actual assessment of the proposed experimental programs