Patent Number: 055966152
Section: claims

1. A fuel assembly for a nuclear reactor comprising fuel assembly elements, said fuel assembly elements comprising: a fuel sheath tube;  a spacer tier holding said fuel sheath tube; and  a channel box for containing a plurality of said sheath tubes,  wherein at least one fuel assembly element comprises a Zr-containing matrix alloy, wherein an average crystal grain size of said matrix alloy is in the range of 1000 nm or less.  a) mechanically mixing a Zr-containing metal and an alloying element, the alloying element being chosen from a group consisting of: Fe, Cr, Ni, Nb, Mo, Te, Bi, and Sn, whereby a Zr alloy is produced;  b) subjecting the Zr alloy to an isostatic pressure, whereby a pressure-treated Zr alloy is produced;  c) crystallizing the pressure-treated Zr alloy in a temperature range of between a crystallization temperature of the pressure-treated Zr alloy and a maximum crystallization temperature, said maximum crystallization temperature being 200 degrees C. above the crystallization temperature of the pressure-treated Zr alloy, whereby a Zr matrix alloy is produced;  d) forming the Zr matrix alloy into a shape of the fuel assembly element.  hydrogenation of the Zr-containing metal;  crushing of the Zr-containing metal into a powder, and;  dehydrogenation of the powder. 2. A fuel assembly as in claim 1 wherein said average crystal grain size is in the range of 100 nm or less. 3. A fuel assembly as in claim 1 wherein at least one of said fuel assembly elements comprises a Zr alloy having a random crystal orientation. 4. A fuel assembly as in claim 1 wherein at least one fuel assembly element comprises a Zr alloy having greater than about 0.02 wt % of Fe. 5. A fuel assembly as in claim 4 wherein at least one fuel assembly element comprises a Zr alloy having at least about 0.05 to 30 wt % of Fe, and an average crystal grain size of said Zr alloy is in the range of 100 nm or less. 6. A fuel assembly as in claim 1 wherein at least one fuel assembly element comprises a ZrFe.sub.2 intermetallic compound containing at least about 33 atomic percent Zr. 7. A fuel assembly as in claim 1 wherein at least one fuel assembly element comprises a ZrFe.sub.2 intermetallic compound containing at least about 66 atomic percent Fe. 8. A fuel assembly as in claim 7 wherein at least one fuel assembly element comprises a ZrFe.sub.2 intermetallic compound containing at least about 33 atomic percent Zr. 9. A fuel assembly as in claim 1 wherein at least one fuel assembly element comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of Zr between about 30 and about 35 atomic percent. 10. A fuel assembly as in claim 1 wherein at least one fuel assembly element comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of (Fe, Ni, Cr, Sn) of between about 65 and about 70 atomic percent. 11. A fuel assembly as in claim 10 wherein at least one fuel assembly element comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of Zr between about 30 and about 35 atomic percent. 12. A fuel assembly element for a nuclear reactor comprising a Zr-containing matrix alloy comprising an average crystal grain size of 1000 nm or less. 13. A fuel assembly element as in claim 12 wherein said average crystal grain size is less than about 100 nm. 14. A fuel assembly element as in claim 12 wherein said Zr-containing metal comprises a Zr alloy having at least about 0.02 wt % of Fe. 15. A fuel assembly element as in claim 14 wherein said Zr-containing metal comprises a Zr alloy having at least about 0.05 to 30 wt % of Fe and an average crystal grain size of said Zr alloy is in the range of 100 nm or less. 16. A fuel assembly element as in claim 12 said Zr-containing metal comprises a ZrFe.sub.2 intermetallic compound containing at least about 33 atomic percent Zr. 17. A fuel assembly element as in claim 12 wherein said Zr-containing metal comprises a ZrFe.sub.2 intermetallic compound containing at least about 66 atomic percent Fe. 18. A fuel assembly element as in claim 17 wherein said Zr-containing metal comprises a ZrFe.sub.2 intermetallic compound containing at least about 33 atomic percent Zr. 19. A fuel assembly element as in claim 12 wherein said Zr-containing metal comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of Zr between about 30 and about 35 atomic percent. 20. A fuel assembly element as in claim 12 wherein said Zr-containing metal comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of (Fe, Ni, Cr, Sn) of between about 65 and about 70 atomic percent. 21. A fuel assembly element as in claim 20 wherein said Zr-containing metal comprises a Zr(Fe, Ni, Cr, Sn).sub.2 intermetallic compound containing a range of Zr between about 30 and about 35 atomic percent. 22. A fuel assembly element manufacturing method comprising: 23. A method as in claim 22 wherein said crystallizing occurs during said subjecting, wherein said subjecting comprises subjecting the Zr alloy to an isostatic pressure at a temperature lower than the crystallization temperature of the Zr alloy. 24. A method as in claim 22 wherein said crystallizing comprises working the pressure-treated Zr alloy at a temperature range between about 100 degrees C. and about 200 degrees C. 25. A method as in claim 24 wherein said subjecting occurs at a temperature above the crystallizing temperature for said Zr alloy. 26. A method as in claim 22 wherein said mechanically mixing comprises: 27. A method as in claim 26 wherein said dehydrogenation comprises heating in a vacuum atmosphere. 28. A method as in claim 22 wherein said Zr-containing metal comprises a powder of pure Zr. 29. A method as in claim 22 wherein said Zr-containing metal comprises a powder of a Zr alloy. 30. A method as in claim 22 wherein the temperature is never allowed above about 650 degrees C. 31. A method as in claim 22 further comprising hot-working, performed below about 650 degrees C. 32. A method as in claim 22 further comprising annealing, performed at a temperature higher than about 530 degrees C.