Irradiation target for radioisotope production, method for preparing and use of the irradiation target

Patent metadata

Field	Value
Publication number	US-10820403-B2
Application number	US-201615546184-A
Country	US
Kind code	B2
Filing date	Jan 19, 2016
Priority date	Jan 29, 2015
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

The invention provides a sintered rare earth metal oxide target for producing a radioisotope in an instrumentation tube of a nuclear power reactor, wherein the sintered target has a density of at least 90 percent of the theoretical density, and wherein the sintered target contains chromium in an amount of from 500 to 2000 μg/g, and Mg and/or Ca in an amount of from 1000 to 6000 μg/g. The sintered target is prepared by providing a rare earth metal oxide powder, blending the rare earth metal oxide powder with chromium oxide, dry granulating and consolidating the powder in a mold to form a spheroidal green body, and sintering the green body in solid phase to form a spheroidal ytterbia target.

First claim

The invention claimed is:

1. A sintered rare earth metal oxide target for producing a radioisotope in an instrumentation tube of a nuclear power reactor, consisting of the rare earth metal oxide doped with chromium in an amount of from 500 to 2000 μg/g, Mg and/or Ca in an amount of from 1000 to 6000 μg/g, aluminum in an amount of between 500 and 8000 μg/g, and unavoidable impurities, wherein the rare earth metal oxide is represented by the general formula R 2 O 3 wherein R is Yb.

2. The target according to claim 1 , having a density of at least 90 percent of the theoretical density.

3. The target according to claim 1 , wherein the rare earth metal is monoisotopic.

4. The target according to claim 1 , wherein the Mg is present in an amount of between 1000 and 6000 μg/g.

5. The target according to claim 1 , having a density of at least 92 percent of the theoretical density.

6. The target according to claim 1 , having a porosity of less than 10%.

7. The target according to claim 1 , comprising pores having a size less than 100 μm.

8. The target according to claim 1 , having an average grain size of 35 μm or more.

9. The target according to claim 1 , wherein the target is spheroidal and has a diameter in a range of from 1 to 5 mm.

10. The target according to claim 1 , wherein the target is resistant to a pneumatic transport pressure of 10 bar and/or an impact velocity of 10 m/s.

11. A method for preparing an irradiation target according to claim 1 , comprising the steps of:
providing a powder blend consisting of a rare earth metal oxide, chromium oxide, aluminum distearate and a binder wherein chromium oxide is present in the powder blend in an amount of from 1000 to 3000 μg/g, and the rare earth metal is ytterbium;
pre-consolidating the powder blend to form granules having a grain size of less than 500 μm, and consolidating the granulated powder blend to form a green body; or
pelletizing the powder blend by agglomeration in a rotating drum or on a rotating disc to form a green body; and
placing the green body on a support comprising Mg and/or Ca and sintering at a temperature of at least 1700° C. to form a sintered rare earth oxide target having a sintered density of at least 90% of the theoretical density.

12. The method according to claim 11 , wherein the powder of the rare earth metal oxide has a purity of greater than 99%.

13. The method according to claim 11 wherein the binder is a metal salt of a fatty acid.

14. The method according to claim 11 , wherein the binder is added to the powder blend in an amount of between 0.01 to 0.1 weight percent.

15. The method according to claim 11 , wherein the powder blend is pre-consolidated using a pressing force in a range between 10 and 50 kN to form a pre-consolidated slug or pellet.

16. The method according to claim 15 , wherein the pre-consolidated slug or pellet is milled and sieved to form the granules.

17. The method according to claim 11 , wherein further binder is added to the granules in an amount of between 5 and 10 weight percent.

18. The method according to claim 11 , wherein the granules are compression molded by hydraulic pressing at a pressing force in a range from 0.1 to 10 kN.

19. The method according to claim 11 , wherein the green body is sintered in a reducing atmosphere comprising hydrogen and an inert gas.

20. A method for producing radioisotopes wherein the sintered rare earth metal oxide target according to claim 1 is inserted in an instrumentation tube of a commercial nuclear power reactor and exposed to neutron flux when in energy producing operation.

21. The method according to claim 20 wherein the commercial nuclear power reactor comprises a system for generating radioisotopes in an operating nuclear reactor vessel comprising an irradiation target drive subsystem having means to produce a pressurized gaseous fluid that interacts with the sintered rare earth metal oxide target to drive the target from a target storage subsystem into the instrumentation tube, and from the instrumentation tube into a removal subsystem after irradiation.

22. The method according to claim 20 comprising inserting the sintered rare earth metal oxide target in an instrumentation tube extending into a reactor core by means of pressurized air and exposing the sintered targets to neutron flux encountered in the nuclear reactor when operating, for a predetermined period of time, so that the sintered target converts to a radioisotope, and removing the sintered target and produced radioisotope from the instrumentation tube.

23. The method according to claim 20 wherein the radioisotope is Lu-177.

Assignees

• Framatome Gmbh

Inventors

• Schuster Beatrice

Classifications

• 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

• C04B35/50

  based on rare-earth compounds {(non-oxide rare earth compounds C04B35/5156)} · CPC title

• G21C1/02

  Fast fission reactors, i.e. reactors not using a moderator {; Metal cooled reactors; Fast breeders} · CPC title