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

Patent metadata

Field	Value
Publication number	US-2017365370-A1
Application number	US-201615546184-A
Country	US
Kind code	A1
Filing date	Jan 19, 2016
Priority date	Jan 29, 2015
Publication date	Dec 21, 2017
Grant date	—

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

1 .- 28 . (canceled)

29 . A sintered rare earth metal oxide target for producing a radioisotope in an instrumentation tube of a nuclear power reactor, wherein the target comprises 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.

30 . The target according to claim 29 consisting of the rare earth metal oxide doped with chromium in an amount of from 1000 to 6000 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.

31 . The target according to claim 29 having a density of at least 90 percent of the theoretical density.

32 . The target according to claim 29 wherein the rare earth metal oxide is represented by the general formula R 2 O 3 wherein R is a rare earth metal selected from the group consisting of Nd, Sm, Y, Dy, Ho, Er, Tm, Yb and Lu.

33 . The target according to claim 32 wherein the rare earth metal is Sm, Y, Ho or Yb.

34 . The target according to claim 32 , wherein the rare earth metal is monoisotopic.

35 . The target according to claim 29 , comprising Mg in an amount of between 1000 and 6000 μg/g.

36 . The target according to claim 29 , comprising aluminum in an amount of between 500 and 8000 μg/g.

37 . The target according to claim 29 , having a density of at least 92 percent of the theoretical density.

38 . The target according to claim 29 , having a porosity of less than 10%.

39 . The target according to claim 29 , comprising pores having a size less than 100 μm.

40 . The target according to claim 29 , having an average grain size of 35 μm or more.

41 . The target according to claim 29 , wherein the target is speroidal and has a diameter in a range of from 1 to 5 mm.

42 . The target according to claim 29 , wherein the target is resistant to a pneumatic transport pressure of 10 bar and/or an impact velocity of 10 m/s.

43 . A method according to preparing an irradiation target according to claim 29 , comprising the steps of:
providing a powder blend consisting of a rare earth metal oxide, chromium oxide and a binder wherein chromium oxide is present in the powder blend in an amount of from 1000 to 3000 μg/g; 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.

44 . The method according to claim 43 , wherein the powder of the rare earth metal oxide has a purity of greater than 99%.

45 . The method according to claim 43 wherein the binder is a metal salt of a fatty acid.

46 . The method according to claim 43 , wherein the binder is added to the powder blend in an amount of between 0.01 to 0.1 weight percent.

47 . The method according to claim 43 , 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.

48 . The method according to claim 47 , wherein the pre-consolidated slug or pellet is milled and sieved to form the granules.

49 . The method according to claim 43 , wherein further binder is added to the granules in an amount of between 5 and 10 weight percent.

50 . The method according to claim 43 , wherein the granules are compression molded by hydraulic pressing at a pressing force in a range from 0.1 to 10 kN.

51 . The method according to claim 43 , wherein the green body is sintered in a reducing atmosphere comprising hydrogen and an inert gas.

52 . The method according to claim 43 , wherein the total amount of Ca and/or Mg in the sintered target is not greater than 6000 μg/g and/or the total amount of aluminum is not greater than 8000 μg/g.

53 . A method for producing radioisotopes wherein the sintered rare earth metal oxide target according to claim 29 is inserted in an instrumentation tube of a commercial nuclear power reactor and exposed to neutron flux when in energy producing operation.

54 . The method according to claim 53 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.

55 . The method according to claim 53 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.

56 . The method according to claim 53 wherein the rare earth metal oxide is ytterbia and the radioisotope is Lu-177.

Assignees

• Areva 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

• C04B2235/3241

  Chromium oxides, chromates, or oxide-forming salts thereof · CPC title

• C04B2235/3224

  Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide · CPC title