b'10 mm w/5mm w/3 mm w/ 3mm 1mm 1mm 10 mm 5mm 3mm 2mmCeO 91.54 90.57 91.173 96.00 96.37 CeO 22UO 2 93.83 88.49 88.8 93.82 85.47 UO 2The geometric densities for the sinteredhigher densities, perhaps due toTable 1. Densities of annular and pellets were 90% dense, and showedthe relief from the annulus surface.small radii pellets fabricated at Los a 14-15% diametric shrinkage on theCompared to pellets previously madeAlamos National Laboratory (LANL) outer diameter after sintering. The largeat the Fuel Research Lab (FRL), theFuel Research Lab.pellets have ~10% shrinkage on theannulus increased the density of inner diameter, with the smaller pelletspellets by an average of 4%.showing up to 20% shrinkage. SinceFor the end goal of helping with nuclear material is of interest, thesequalification, the microstructure preliminary studies show a level ofeffects of the annulus are also success that indicate the recipe will workimportant. New pressing defects in a glovebox with materials of interest. are expected due to new interaction Uranium dioxide is the industry stan- surfaces, particularly the surface of the dard for fuel and will be a necessaryannulus with the die. Not only does benchmarking fuel for the acceleratedthe increased contact area/volume burnup testing. Historic knowledgeratio increase, but the relaxation and on solid pellets meant prioritizingsintering processes might change as the annular pellets, hence the 10 mmwell, since they have an extra surface and 3 mm pellet checks for UO 2 . Forto precipitate new defect behavior. these tests, depleted Uranium wasA 3 mm w/1mm annulus pellet used because of the reduced hazardswas examined and found to contain associated with it, but will behave thesome noticeable pressing defects. The same for when higher enrichmentsannulus of the pellet left a smooth are used later for the actual irradiationbore, which is the geometry we testing. The annular pellets rangedwould ideally want for using pellets. from 87.5-93.9% dense which is wellOn the other hand, there are clear within successful parameters for andefects presented as pores that run exploratory study without specificperpendicular to the direction of process improvements. Additionally,pressing. These are likely caused from comparison of the 3mm annulareither a lack of pressure that caused pellets to ~3mm monolithic pelletsincomplete compressing of the gives strong credence to the idea thatpowder due to a low pressure during annular pellets can actually achieveinitial testing.2019|AFC ACCOMPLISHMENTS 177'