b'an increase in sintering time canReferences:stimulate grain growth, which can[1.] J. Arborelius, "Advanced doped be further enhanced by an oxidizingUO 2pellets in LWR applications," atmosphere. Figure 1 summaries theJournal of Nuclear Science and effect of sintering time and atmo- Technology, vol. 43, no. 9, pp. sphere on grain growth in undoped967-976, 2006.fuel. The increase in sintering time[2.] L. Bourgeois, P. Dehaudt, C. Le-from 12 to 24 hours did not producemaignan, and A. Hammou, Factors significant improvement in grain sizegoverning microstructure develop-for samples under Ar atmosphere,ment of Cr 2 O 3 -doped UO 2during however there was improvement insintering, J. Nucl. Mater., vol. 297, the size from 4 to 12 hours. The oppo- no. 3, pp. 313326, 2001.site effect is true for samples sintered under a fixed O/M ratio of 2.1. The[3.] S. Kashibe and K. Une, "Effects average grain size of 19.2 m10.2of additives (Cr 2 O 3 , Al 2 O 3 , SiO 2 , m, for the 4 hours CO 2is similar toMgO) on diffusional release of those obtained for Cr 2 O 3doped UO 2 133-Xe from UO 2fuels," Journal pellets fabricated at 1525 C for 4of Nuclear Materials, vol. 254, pp. hours [2]. Furthermore, the sizes at 12234-242, 1998.hours and 24 hours are in line with[4.] Kutty, T.R.G., Hegde, P.V., Khan, Cr 2 O 3doped UO 2pellets fabricated atK.B., Basak, U., Pillai, S.N., Sen-1625 C for 4 hours, Figure 2 showsgupt, A.K. Jain, G.C., Majumdar, a comparison of between an undopedS., Kamath, H.S., Purushotham, UO 2sintered for 12 hours under CO 2 D.S.C., (2002) Densification of Figure 2(a) with a 0.05 wt% Cr 2 O 3 UO 2in six different atmospheres, doped UO 2sintered under H2 +Journal of Nuclear Materials, 305: 1 vol% H 2 O from [2] Figure 2(b).159-168. Averaged grain size of 36.415.1 m have being attained from sintering[5.] I. Amato, R. L. Colombo and A. in CO 2gas for 24 hours, which isP. Balzari, "Grain growth in pure comparable to grain sizes that areand titania-doped uranium diox-achieved by commercial processes. Theide," Journal of Nuclear Materials, results from this study will enable thevol. 18, pp. 252-260, 1966.fabrication of undoped UO 2control[6.] G. Arthur and D. Scott, "The effect test articles for future FGR irradiationof TiO 2additions on the sintering studies to enable quantitative compari- of UO 2 ,"British Ceramic Society sons with ATF doped UO 2commer- Transactions, vol. 63, pp. 417-cially produced fuels. 429, 1964.2020|AFC ACCOMPLISHMENTS 57'