Patent Number: 042971691
Section: claims

1. For use in a nuclear reactor, an oxide composition nuclear fuel material in compacted pellet form containing at least one fissionable isotope and an amount of a chemical displacement compound selected from the group consisting of CuFe.sub.2 O.sub.4 and CuTiO.sub.3 and mixtures thereof effective to immobilize cadmium resulting from nuclear fission chain reactions of the nuclear fuel material through a reaction between the said cadmium and the said chemical displacement compound and thereby prevent cadmium embrittlement of nuclear fuel cladding at reactor operating temperatures. 2. The composition of claim 1 in which the nuclear fuel material comprises compounds selected from the group consisting of uranium oxide compounds, plutonium oxide compounds, thorium oxide compounds and mixtures thereof. 3. The composition of claim 1 in which the nuclear material comprises uranium oxide compounds. 4. The composition of claim 1 in which the immobilizing additive is CuFe.sub.2 O.sub.4. 5. The composition of claim 1 in which the immobilizing additive is CuTiO.sub.3. 6. The composition of claim 1 in which the chemical displacement compound additive is CuTiO.sub.3 in an amount between about 0.0025 and 0.025 weight percent on the basis of the nuclear fuel material. 7. The composition of claim 1 in which the chemical displacement compound is CuFe.sub.2 O.sub.4 in an amount between about 0.0033 weight percent and 0.033 weight percent on the basis of the nuclear fuel material. 8. The composition of claim 1 in which the chemical displacement compound additive is present in an amount approximately 0.01 weight percent on the basis of the nuclear fuel material. 9. The method of immobilizing fission product cadmium generated in nuclear fuel material of oxide composition in pellet form containing at least one fissionable isotope which comprises the step of providing in contact with the nuclear fuel material an amount of a chemical displacement compound selected from the group consisting of CuFe.sub.2 O.sub.4 and CuTiO.sub.3 and mixtures thereof effective to immobilize the cadmium generated in the nuclear fission chain reaction of the nuclear fuel material through a reaction between the said cadmium and the said chemical displacement compound and thereby prevent cadmium embrittlement of nuclear fuel cladding at reactor operating temperatures. 10. The method of claim 9 in which the chemical displacement compound additive is mixed with and distributed through the nuclear fuel material. 11. The method of claim 9 in which the chemical displacement compound additive is disposed in contact with the pellet of nuclear fuel material.