Development of an accident-tolerant fuel composite from uranium mononitride (UN) and uranium sesquisilicide (U3 Si2) with increased uranium loading

Abstract

The processing steps necessary to prepare a potential accident-tolerant fuel composite consisting of uranium mononitride (UN) combined with uranium sesquisilicide (U 3 Si 2) are described. Liquid phase sintering was performed with U 3 Si 2 as the liquid phase combined with UN powder or UN m-spheres. Various UN to U 3 Si 2 ratios were tested which resulted in up to 94% dense pellets. Composite UN-U 3 Si 2 samples had greater than 30% more uranium content than UO 2 .

Phase equilibria in the U-Si system from first-principles calculations

“…Work on U 3 Si 2 -Al dispersion fuels [9][10][11] and UN-U 3 Si 2 composites [12] suggest that U 3 Si 2 may be a viable option for LWRs as compared to U 3 Si. A number of recent efforts have shown U 3 Si 2 may be manufactured via methods such as powder metallurgy [13], ball milling [14] and arc melting [15,16].…”

Neutronics Assessment of Accident-Tolerant Fuel in Advanced Power Reactor 1400 (APR1400)

“…However, in this study, three different advanced fuels were considered. The preferred fuels for ATF system were U 3 Si 2 [12][13][14][15], UN + U 3 Si 2 [16][17][18], and UC [19]. The thermophysical properties of the three advanced fuels and UO 2 fuels for the APR1400 fuel assembly are summarized and compared in Table 1 including fuel density , heavy metal density , average fuel temperature ̅ , thermal conductivity , specific heat , and fuel melting temperature .…”

Experimental and computational assessment of U Si N ternary phases

“…A UN/U 3 Si 2 composite fuel (10-40 vol.% U 3 Si 2 ) has recently been recommended to deal with some of the aforementioned issues [15,16,17]. The central concept for this composite fuel is to combine the better U 3 Si 2 pulverization resistance in an oxidation atmosphere, with the high fissile density of UN.…”

“…Despite being of more recent interest, the initial concept for the UN/U 3 Si 2 composite fuel was developed in the early 1960's [16][17][18] , with the goal to improve the sintering of UN. The composite fuel was proposed as an alternative for required very high sintering temperatures of UN, where the UN/U 3 Si 2 combination takes advantage of liquid-phase sintering fostered by the U 3 Si 2 , achieving suitable densities at T < 1600 °C.…”