Composite uranium silicide-uranium dioxide nuclear fuel
Described herein are Uranium silicide materials as advanced nuclear fuel replacements for uranium dioxide fuel in light water reactors (LWRs) that have advantages over currently used uranium dioxide (UO 2 ) via a substantially higher thermal conductivity and, thus, are capable of operating in a reactor at significantly lower temperatures for the same level of power production, plus the heat capacity of a silicide is lower than that of an oxide so that less heat is stored in the fuel that would need to be removed under accident conditions.
1 . A replacement nuclear fuel pellet comprising:
an outermost layer of the replacement nuclear fuel pellet formed as a layer of UO 2 enclosing at least one silicide comprising U 3 Si 2 ;
uranium dioxide powder;
wherein the at least one silicide has higher thermal conductivity than uranium dioxide; and
wherein the at least one silicide is formed as multiple separate silicide particles displaced within an interior of the nuclear fuel pellet and the uranium dioxide powder is formed as dense, fine grained powder configured to surround each of the multiple separate silicide particles and fill an intervening space between each of the multiple separate silicide particles within the interior of the nuclear fuel pellet to form a silicide grain boundary barrier configured to prevent water, steam or oxygen from contacting the multiple separate silicide particles wherein the uranium dioxide powder is further configured to fill an interior of the replacement fuel pellet while surrounding the multiple separate silicide particles.
2 . The replacement nuclear fuel of claim 1 , wherein the multiple separate silicide particles are sized from 1 μm to 100 μm.
3 . The replacement fuel of claim 1 , wherein the multiple separate silicide particles are present by at least 51% by volume in the fuel pellet.
4 . The replacement fuel of claim 1 , wherein the size of the at least one particle of uranium dioxide powder ranges from 1 to 100 microns.
5 . A method for making a nuclear fuel pellet comprising:
forming an outermost layer of the nuclear fuel pellet as a layer of UO 2 configured to enclose:
forming a pellet from:
at least one silicide comprising U 3 Si 2 ;
uranium dioxide powder; and
at least one ceramic binder;
forming at least one green body from the above;
sintering the at least one green body in a controlled oxygen furnace to form a nuclear fuel pellet;
wherein the at least one silicide comprises at least 51% of the volume of the nuclear fuel pellet; and
configuring the at least one silicide as multiple separate silicide particles displaced within an interior of the nuclear fuel pellet completely surrounded by the uranium dioxide powder, which is configured as a dense, fine grained powder configured to form a silicide grain boundary barrier configured to surround each of the multiple separate silicide particles and fill an intervening space between each of the multiple separate silicide particles within the interior of the nuclear fuel pellet to prevent to prevent water, steam or oxygen from contacting the multiple separate silicide particles.
6 . The method of claim 5 , wherein the multiple separate silicide particles are sized from 1 μm to 100 μm.
7 . The method of claim 5 , wherein the multiple separate silicide particles are present from 52-75% by volume in the pellet.
8 . The method of claim 5 , wherein size of uranium dioxide powder particles ranges from I to I 00 microns.