Mn-doped oxide nuclear fuel
A nuclear fuel includes uranium(IV) oxide (UO 2 ) and manganese (Mn) as a dopant. The Mn dopant may be present in the fuel in an amount up to the solubility limit for Mn under a given set of conditions, for example, about 0.01 wt % to about 1 wt %. The nuclear fuel is substantially free of aluminum (Al). The nuclear fuel exhibits enhanced grain size development during sintering temperatures as low at 1400 K due to an increase in uranium sub-lattice vacancies induced by dissolution of the Mn dopant at interstitial defect sites. The Mn-doped nuclear fuel exhibits improved grain sizes at lower temperatures compared to Cr-, Al-, and undoped UO 2 , and therefore desirably exhibits lower fission gas release and higher plasticity, reducing the chances of fuel rod failure.
1. A nuclear fuel pellet comprising uranium(IV) oxide (UO 2 ) and manganese (Mn) atoms, the Mn atoms being present in the nuclear fuel pellet in an amount of about 0.1 wt % to about 1 wt % based on the total weight of the nuclear fuel pellet; and
the nuclear fuel pellet being substantially free of aluminum (Al).
2. The nuclear fuel pellet of claim 1 , wherein the Mn atoms are derived from a manganese salt having one or more counter anions, the one or more counter anions each comprising an oxide anion, a nitride anion, a stearate anion, a chloride anion, or a hydroxide anion.
3. The nuclear fuel pellet of claim 2 , wherein the Mn atoms are derived from a manganese oxide.
4. The nuclear fuel pellet of claim 3 , wherein the manganese oxide is Mn 2 O 3 .
5. The nuclear fuel pellet of claim 1 , wherein the Mn atoms are present in the nuclear fuel pellet in an amount of about 0.1 wt % to about 0.5 wt % based on the total weight of the nuclear fuel pellet.
6. The nuclear fuel pellet of claim 1 , wherein the Mn atoms have an interstitial concentration of about 0.001 to about 0.5 fractional defects per unit of UO 2 at a sintering temperature above about 1430 K.
7. The nuclear fuel pellet of claim 6 , wherein the Mn atoms have an interstitial concentration of about 0.01 to about 0.1 fractional defects per unit of UO 2 at a sintering temperature above about 1700 K.
8. The nuclear fuel pellet of claim 1 , wherein the nuclear fuel pellet has a grain size enhancement factor over undoped UO 2 of about 1.1 to about 35 times after sintering at about 1700 K to about 3200 K.
9. The nuclear fuel pellet of claim 8 , wherein the nuclear fuel pellet has a grain size enhancement factor over undoped UO 2 of about 1.3 to about 14 times after sintering at about 1700 K to about 2000 K.
10. The nuclear fuel pellet of claim 1 , wherein the nuclear fuel pellet further comprises active nuclides other than uranium.
11. The nuclear fuel pellet of claim 10 , wherein the active nuclides other than uranium comprise thorium (Th), plutonium (Pu), or a mixture thereof.
12. A method of manufacturing a nuclear fuel pellet comprising:
mixing uranium(IV) oxide (UO 2 ) and a manganese (Mn) dopant in the absence of added aluminum (Al) to yield a fuel composition that is substantially free of aluminum;
pressing the fuel composition into a pellet; and
sintering the pellet, the resulting pellet having a Mn atom concentration of about 0.1 wt % to about 1 wt % based on the total weight of the fuel composition.
13. The method of claim 12 , wherein the Mn dopant is derived from a manganese salt having one or more counter anions, the one or more counter anions each comprising an oxide anion, a nitride anion, a stearate anion, a chloride anion, or a hydroxide anion.
14. The method of claim 13 , wherein the Mn dopant is derived from a manganese oxide.
15. The method of claim 14 , wherein the manganese oxide is Mn 2 O 3 .
16. The method of claim 12 , wherein the sintering the pellet is carried out at a temperature of about 1430 K to about 3200 K.
17. The method of claim 16 , wherein the sintering the pellet is carried out at a temperature of about 1700 K to about 2000 K.
18. The method of claim 13 , wherein the mixing the UO 2 and the manganese (Mn) dopant comprises co-milling the UO 2 and the manganese (Mn) dopant to an average particle size of less than 500 μm.
19. The method of claim 12 , wherein the sintering the pellet is carried out at a temperature of 1770 K to 3200 K.
20. The method of claim 12 , wherein the mixing the UO 2 and the manganese (Mn) dopant comprises co-milling the UO 2 and the manganese (Mn) dopant to an average particle size of less than 100 μm.