Separation of isotopes by ionisation for processing of nuclear fuel materials

• US 6,323,455 B1
• Filed: 04/19/1999
• Issued: 11/27/2001
• Est. Priority Date: 03/15/1996
• Status: Expired due to Fees

• Current Assignee: Nexia Solutions Limited
• Original Assignee: British Nuclear Technology
• Inventors: Witts, David John, Bailey, Geoffrey Horrocks, Whitehead, Colin
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US09/142,737
• Time in Patent Office: 953 Days
• Field of Search: 219/121.43, 219/121.55, 219/121.52, 219/121.59, 219/121.36, 204/298.12, 376/409, 250/290-295, 250/283, 250/284, 156/345
• US Class Current: 219/121.59
• CPC Class Codes: B01D 59/48 using electrostatic and magnetic fields
• CPC Class Codes: B01D 59/50 Separation involving two or more processes covered by different groups selected from groups B01D59/02, B01D59/10, B01D59/20, B01D59/22, B01D59/28, B01D59/34, B01D59/36, B01D59/38, B01D59/44
• CPC Class Codes: G21C 19/48 Non-aqueous processes
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors
• CPC Class Codes: Y02W 30/50 Reuse, recycling or recovery technologies

Abstract

Processing apparatus and methods are provided which involve the selective ionization of a feed material; the separation of ionized and non-ionized species; a selective excitation of the still ionized species; introduction of a chemical material to cause selective transition to a non-ionized state of part of the feed; and a further separation of ionized and non-ionized species. Other improvements in selective excitation based processing are also disclosed. Separation of isotopes and/or elements from one another and changing chemical and physical form is provided in a single process from a variety of feeds.

Claims

1. A process for separating one or more ionized components at elevated kinetic energy from one or more components at lower kinetic energy, the process comprising providing a process stream containing the elevated and lower kinetic energy components;

introducing a chemical material to the process stream and wherein the introduced chemical material contacts both the elevated and lower kinetic energy level components;

contact with the elevated kinetic energy components resulting in a still ionized form of that component and contact with the lower kinetic energy component resulting in a non-ionized form of that component, the separation being based on the ionized and/or non-ionized state of the components.

2. The process of claim 1 where the elevated and lower energy level for the components are provided using ion cyclotron resonance.

3. The process of claim 1 wherein the added chemical material consists of an un-ionized gas.

4. The process of claim 1 and comprising the further step of introducing a further chemical material and contacting this with the remaining ionized component, the kinetic energy of the ionized component and further chemical material being such that a non-ionized component or particle results.

5. The process according to claim 4 wherein introducing the further chemical material and/or a further additional chemical material to the component reduces the kinetic energy to a stage where a solid product is produced.

6. The process according to claim 1 wherein ionization of the components is caused by the temperature of a plasma and/or the interaction of the components with high energy electrons produced by electron cyclotron resonance.

7. The process according to claim 1 wherein the chemical material added at a predetermined kinetic energy comes into contact with the elevated energy component and into contact with the lower energy component;

the kinetic energy of the chemical material, elevated energy component and lower energy component being such that contact between the elevated energy component and the chemical material results in an ion of, or including, that component; and

the coming together of the lower energy component and the chemical material results in a non-ionized particle of, or including, that component.

8. The process of claim 7 wherein the amount of the chemical material added to the process is selected to control the extent to which the lower energy component is converted to the non-ionized form.

9. The process of claim 1 wherein the separated component is one or more isotopes which have been separated from other isotopes of the same and/or other elements.

10. The process of claim 1 wherein the degree of separation between the components is only partial, such that a proportion of the component in the feed is extracted as nonionized components in the process whilst the majority of that component continues into the product stream produced from the ionized components and/or vice versa.

11. A process according to claim 1 and further comprising the preliminary steps of:

a) providing a feed, the feed consisting of mixed components;

b) converting said feed into a plasma and/or ionized form;

c) providing at least one component in at least partially ionized form and at least one different component in at least partially non-ionized form;

d) containing said ions and/or plasma in a magnetic field; and

e) separating at least a portion of said ionized components from at least a portion of said non-ionized components, and wherein the separated ionized components and/or separated non-ionized components are then separately subjected to a process according to claim 3.

12. The process according to claim 1 comprising the step of applying an oscillating electric field to the ionized component, the oscillating electric field having a component perpendicular to the axis of a containing magnetic field, the electric field oscillating at a frequency close to the ion cyclotron frequency, or an harmonic thereof, of one or more components or one or more isotopes of a component present.

13. The process according to claim 12 in which the ionized components from the separation of claim 11 are neutralised prior to entering the containing magnetic field of claim 12.

14. The process of claim 13 in which the addition of a chemical material effects the neutralisation of the ionized components.

15. The process according to claim 13 in which the neutralised components are at least partially ionized following entry to the containing magnetic field.

16. The process of claim 1 wherein the added chemical material is oxygen.

17. The process of claim 1 wherein the mixed components of the feed contain ²³⁸U and ²³⁵U.

18. The process of claim 17 wherein the ²³⁵U is solidified under conditions of pressure, temperature, chemical addition and collection method to give ceramic grade uranium dioxide.

19. The process according to claim 1 in which the process is used to remove fission products from spent nuclear fuel.

20. The process according to claim 1 in which the process is used to remove specific plutonium and/or uranium isotopes from spent nuclear fuel.

30. A process according to claim 21 and further comprising the preliminary acts of:

providing a feed, the feed consisting of mixed components;

converting said feed into a plasma and/or ionized form comprising at least one component in at least partially ionized form and at least one different component in at least partially non-ionized form;

containing said ions and/or plasma in a magnetic field; and

separating at least a portion of said ionized components from at least a portion of said non-ionized components, and wherein the separated ionized components or the separated non-ionized components are then separately subjected to the process according to claim 1.

21. A process comprising the steps of:

providing a feed of mixed components in a magnetic field, the mixed components including ionized first components and ionized second components, the ionized first components and the ionized second components each having an average kinetic energy;

increasing the average kinetic energy of the ionized first components and the ionized second components so that the average kinetic energy of the ionized first components is greater than the average kinetic energy of the ionized second components;

introducing a chemical material into the feed of mixed components, the chemical material interacting with the ionized first components and the ionized second components such that a majority of the ionized second components become non-ionized, a majority of the ionized first components remaining ionized; and

substantially separating the remaining ionized first components from the non-ionized second components.

22. The process of claim 21 where the act of increasing the average kinetic energy of the ionized first components and the ionized second components is accomplished using ion cyclotron resonance.

23. The process of claim 21 wherein the chemical material consists of an non-ionized gas.

24. The process of claim 21 comprising the further act of introducing a further chemical material to the separated remaining ionized first components, the kinetic energy of the remaining ionized first components and further chemical material being such that a non-ionized component or particle results.

25. The process according to claim 24 wherein the act of introducing the further chemical material to the remaining ionized first component reduces the kinetic energy of the first component to a stage where a solid product is produced.

26. The process according to claim 21 wherein the first components and second components are initially ionized by the temperature of a plasma or the interaction of the components with high energy electrons produced by electron cyclotron resonance.

27. The process according to claim 21 wherein the chemical material added at a predetermined kinetic energy comes into contact with the ionized first component and into contact with the ionized second component;

the kinetic energy of the chemical material, ionized first component, and ionized second component being such that contact between the ionized first components and the chemical material results in a ion of, or including, that first components; and

the coming together of the ionized second component and the chemical material results in a non-ionized particle of, or including, that the second component.

28. The process of claim 27 wherein the amount of the chemical material added to the process is selected to control the extent to which the ionized second component is converted to the non-ionized form.

29. The process of claim 21 wherein the separated first components are one or more isotopes which have been separated from other isotopes of the same or other elements.

31. The process according to claim 21 wherein the act of increasing the average kinetic energy comprises applying an oscillating electric field to the ionized first and second component, the oscillating electric field having a component perpendicular to the axis of the containing magnetic field, the electric field oscillating at a frequency close to the ion cyclotron frequency, or an harmonic thereof, of the first or second components or one or more isotopes thereof.

32. A process comprising the steps of:

subjecting a feed of mixed components comprising ionized ²³⁵U and ionized ²³⁸U to ion cyclotron resonance, the ion cyclotron resonance causing the ionized ²³⁵U to have an average kinetic energy that is greater than an average kinetic energy of the ionized ²³⁸U;

introducing a chemical material into the feed of mixed components, the chemical material interacting with the ²³⁵U and ²³⁸U so as to leave at least a portion of the ²³⁵U of the feed in ionized form and at least a portion of the ²³⁸U of the feed in non-ionized form;

substantially separating the ionized ²³⁵U from the non-ionized ²³⁸U; and

solidifying the separated ²³⁵U to give ceramic grade uranium dioxide.

33. A process comprising the steps of:

providing a feed of mixed components in a magnetic field, the mixed components including ionized first components and ionized second components, the ionized first components and the ionized second components each having an average kinetic energy;

increasing the average kinetic energy of ionized first components and the ionized second components so that the average kinetic energy of the ionized first components is greater than the average kinetic energy of the ionized second components;

introducing a chemical material into the feed of mixed components so that the chemical material reacts with at least a portion of the ionized second components so as to form the at least portion of ionized second components into non-ionized third components, a majority of the ionized first components remaining ionized; and

substantially separating the remaining ionized first components from the non-ionized third components.

34. A process according to claim 33 wherein the act of introducing the chemical material comprises the chemical material being oxygen.

35. A process according to claim 33 wherein the act of introducing the chemical material comprises the chemical material having an average kinetic energy that is lower than the average kinetic energy of the first components and the second components.

36. A process according to claim 33 wherein the first components and the second components comprise isotopes of the same material.

37. A process comprising the steps of:

providing a feed of mixed components in a magnetic field, the mixed components including an ionized first component having a kinetic energy and an ionized second component having a kinetic energy, the first component and second component each consisting of a discrete atom or molecule;

increasing the kinetic energy of the ionized first component and the ionized second component, the kinetic energy of the first component being increased more than the kinetic energy of the second component;

introducing oxygen into the feed of mixed components so that the oxygen interacts with the ionized second component so that the second component becomes non-ionized, the ionized first component remaining ionized; and

separating the ionized first component from the non-ionized second component.

38. A process according to claim 37, wherein the act of the oxygen interacting with the ionized second component comprises the oxygen reacting with the second component so as to form a non-ionized third component.

39. A process according to claim 37, wherein the oxygen interacts with the second component to decrease the kinetic energy of the second component without reacting with the second component.

40. A process according to claim 37 wherein the first component comprises ²³⁵U and the second component comprises ²³⁸U.