Method of preparing of irradiation targets for radioisotope production and irradiation target

Patent metadata

Field	Value
Publication number	US-10714224-B2
Application number	US-201515545807-A
Country	US
Kind code	B2
Filing date	Jan 29, 2015
Priority date	Jan 29, 2015
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The invention provides a method of preparing irradiation targets for radioisotope production in instrumentation tubes of a nuclear power reactor, the method comprising the steps of: providing a powder consisting of an oxide of a rare earth metal having a purity of greater than 99% and, optionally, an organic binder; pelletizing the powder and optionally the organic binder to form a substantially spherical green body having a diameter of from between 1 to 10 mm; and sintering the spherical green body in solid phase at a temperature of at least 70 percent of a solidus temperature of the rare earth metal oxide powder and for a time sufficient to form a round sintered rare earth metal oxide target having a sintered density of at least 80 percent of the theoretical density.

First claim

The invention claimed is:

1. A method for preparing irradiation targets for radioisotope production in instrumentation tubes of a nuclear power reactor, the method comprising the steps of:
providing a powder consisting of an oxide of a rare earth metal having a purity of greater than 99% and, optionally, an organic binder;
agglomerating the powder and the optional organic binder in a rotating drum or on a rotating disc so as to pelletize the powder and the optional organic binder and to form the powder and the optional organic binder into a substantially spherical green body having a diameter of from between 1 to 10 mm, and
sintering the green body in solid phase at a temperature of at least 70 percent of a solidus temperature of the rare earth metal oxide powder and for a time sufficient to form a substantially spherical sintered rare earth metal oxide target having a sintered density of at least 80 percent of the theoretical density.

2. The method of claim 1 wherein the rare earth metal is selected from the group consisting of Nd, Sm, Y, Dy, Ho, Er, Tm, Yb and Lu.

3. The method of claim 2 wherein the rare earth metal is Sm, Y, Ho or Yb.

4. The method of claim 1 wherein the powder of the rare earth metal oxide has a purity of greater than 99.9 percent.

5. The method of claim 1 wherein the rare earth metal is monoisotopic.

6. The method of claim 1 wherein the organic binder is added to the powder before or during the pelletizing of the rare earth metal oxide powder.

7. The method of claim 6 wherein the organic binder is added to the powder during pelletizing by spraying an aqueous solution of the binder onto the powder of the rare earth metal oxide.

8. The method of claim 1 wherein the organic binder is selected from the group consisting of polyvinyl alcohol and methylcellulose.

9. The method of claim 1 wherein the green bodies contain the organic binder in an amount of up to 1 weight percent, based on the total weight of the green bodies.

10. The method of claim 1 wherein the sintering temperature is between 70 and 80 percent of the solidus temperature of the rare earth metal oxide.

11. The method of claim 1 wherein the sintering temperature is in a range of from 1650 to 1800° C.

12. The method of claim 1 wherein the green body is sintered for a time of from 4 to 24 hours.

13. The method of claim 1 wherein the green body is sintered under atmospheric pressure.

14. The method of claim 1 wherein the green body is sintered in an oxidizing atmosphere.

15. The method of claim 1 wherein the green body is sintered in an atmosphere consisting of nitrogen and oxygen.

16. The method of claim 1 wherein the green body is sintered to a density of at least 90 percent of the theoretical density.

17. The method of claim 1 wherein the sintered target has a porosity of less than 10%.

18. The method of claim 1 wherein the sintered target has a diameter in a range of from 1 to 5 mm.

19. A sintered rare earth metal oxide target obtained by the method according to claim 1 , wherein the sintered target is substantially spherical and has a density of at least 80 percent of the theoretical density, and wherein the rare earth metal oxide has a purity of greater than 99%.

20. The target of claim 19 wherein the target is resistant to a pneumatic transport pressure of 10 bar and an impact velocity of 10 m/s.

21. A method for producing radioisotopes wherein the sintered rare earth metal oxide target of claim 19 is inserted in an instrumentation tube of a nuclear power reactor and exposed to neutron flux when in energy producing operation.

22. The method according to claim 21 wherein the rare earth metal oxide is ytterbia and the radioisotope is Lu-177.

23. The method of claim 2 wherein the rare earth metal is Yb-176.

24. The method of claim 1 wherein the sintered target has a diameter in a range of from 1 to 3 mm.

Assignees

• Framatome Gmbh

Inventors

• Schuster Beatrice
• Schmid Wolfgang

Classifications

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21G1/02 Primary

  in nuclear reactors (by thermonuclear reactions G21B; conversion of nuclear fuel G21C) · CPC title

• H05H6/00 Primary

  Targets for producing nuclear reactions (supports for targets or objects to be irradiated G21K5/08 {; preparation of tritium C01B4/00; targets, e.g. pellets for fusion reactions by laser or charged particles beam injection H05H1/22}) · CPC title