FUEL FABRICATION PROCESSES, DESIGN AND EXPERIMENTAL CONDITIONS FOR THE JOINT UNITED-STATES-SWISS MIXED CARBIDE TEST IN FFTF (AC-3 TEST)

The preparation of mixed carbide fuel for a joint (US-Swiss) irradiati on test in the US Fast Flux Test Facility (FFTF) is described, togethe r with the experiment design and the irradiation conditions. Two fabri cation routes were compared. The US produced 66 fuel pins containing p ellet fuel via the powder-pellet (dry) route, and the Swiss group prod uced 25 sphere pac pins of mixed carbide using the internal gelation ( wet) route. Both sets of fuel met all the requirements of the specific ations concerning stoichiometry, chemical composition and structure. T he pin designs were as similar as possible. The test operated successf ully in the FFTF for 620 effective full power days until October 1988 and reached over 8% burn up with peak powers of around 80 kW/m. The co nclusions were that the choice of sphere pac or pellet fuel for reacto r application is dependent on preferred differences in fabrication (e. g. economics and environmental factors) and not on differences in irra diation behaviour.