High density fuel development for research reactors

An international effort to develop, qualify, and license high and very high density fuels has been underway for several years within the framework of multiple national RERTR programs. The current state of development is the result of significant contributions from many laboratories, specifically CNEA in Argentina, AECL in Canada, CEA in France, TUM in Germany, KAERI in Korea, VNIIM, RDIPE, IPPE, NCCP and RIARR in Russia, ANL and INL in USA. These programs are mainly engaged on UMo dispersion fuels with densities from 6 to 9 gU/cm3 (high density fuel) and UMo monolithic fuel with density as high as 16 gU/cm3 (very high density fuel).The limitations discovered under severe (high power) operating conditions during tests on first generation high density fuel, postponed initial plans and schedules for qualification tests and the subsequent licensing program. To solve the problem, full scientific and experimental programs were launched to understand the mechanism of UMo/Al interaction, develop and test in-pile solutions to avoid an inappropriate behavior under irradiation. The most promising remedies for dispersion fuel appears to be an addition of silicon to the matrix or the oxidation of the particles without any additive in Al matrix. For monolithic fuel, tests are in progress to improve cohesion between foil and clad during and after irradiation. Promising solutions include the application of a silicon rich layer to the interface between the cladding and fuel, application of a zirconium diffusion barrier to the interface, or by using Zy cladding co-rolled with the UMo foil