Method and composition for moderated nuclear fuel

1. A nuclear fuel composition comprising:

a transuranic fuel; and

a neutron moderator including hafnium hydride, mixed with the transuranic fuel, wherein a ratio of hydrogen to hafnium in the hafnium hydride is 1.6-1.7.

2. The nuclear fuel composition as recited in claim 1 , including 8 wt %-45 wt % of the transuranic fuel and a balance of the neutron moderator.

3. The nuclear fuel composition as recited in claim 1 , further comprising a neutron moderator diluent mixed with the transuranic fuel and the neutron moderator.

4. The nuclear fuel composition as recited in claim 3 , wherein the neutron moderator diluent is selected from a group consisting of iron, tungsten, rhenium, and combinations thereof.

5. A nuclear fuel composition comprising:

8 wt %-45 wt % of a plutonium transuranic fuel; and

a balance of a neutron moderator mixed with the transuranic fuel, the neutron moderator including hafnium hydride.

6. The nuclear fuel composition as recited in claim 5 , wherein the neutron moderator includes a neutron moderator diluent.

7. The nuclear fuel composition as recited in claim 6 , wherein the neutron moderator diluent is selected from a group consisting of iron, tungsten, rhenium, and combinations thereof.

8. The nuclear fuel composition as recited in claim 1 , wherein the neutron moderator includes an iron neutron moderator diluent.

9. The nuclear fuel composition as recited in claim 1 , wherein the neutron moderator includes a tungsten neutron moderator diluent.

10. The nuclear fuel composition as recited in claim 1 , wherein the neutron moderator includes a rhenium neutron moderator diluent.

11. The nuclear fuel composition as recited in claim 1 , wherein the neutron moderator includes a neutron moderator diluent in an amount greater than an amount of the hafnium hydride.

12. The nuclear fuel composition as recited in claim 5 , wherein a ratio of hydrogen to hafnium in the hafnium hydride is 1.6-1.7.