WO1996011477A1 - The treatment of liquids - Google Patents

The treatment of liquids Download PDF

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Publication number
WO1996011477A1
WO1996011477A1 PCT/GB1995/002357 GB9502357W WO9611477A1 WO 1996011477 A1 WO1996011477 A1 WO 1996011477A1 GB 9502357 W GB9502357 W GB 9502357W WO 9611477 A1 WO9611477 A1 WO 9611477A1
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WO
WIPO (PCT)
Prior art keywords
neptunium
aqueous
liquid
radioactive
species
Prior art date
Application number
PCT/GB1995/002357
Other languages
French (fr)
Inventor
Iain Stewart Denniss
Robin John Taylor
Original Assignee
British Nuclear Fuels Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Nuclear Fuels Plc filed Critical British Nuclear Fuels Plc
Publication of WO1996011477A1 publication Critical patent/WO1996011477A1/en

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange
    • G21F9/125—Processing by absorption; by adsorption; by ion-exchange by solvent extraction
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
    • G21C19/42—Reprocessing of irradiated fuel
    • G21C19/44—Reprocessing of irradiated fuel of irradiated solid fuel
    • G21C19/46—Aqueous processes, e.g. by using organic extraction means, including the regeneration of these means
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

Definitions

  • the present invention relates to the treatment of liquids.
  • it relates to the treatment of liquids containing radioactive species to separate radioactive waste or contaminant species contained therein.
  • the spent fuel is dissolved in a strong acid, eg concentrated nitric acid, which is added to an aqueous phase flow which is contacted by an organic extractant solvent such as tributyl phosphate to extract recyclable uranium and plutonium ions.
  • a strong acid eg concentrated nitric acid
  • an organic extractant solvent such as tributyl phosphate to extract recyclable uranium and plutonium ions.
  • Radioactive waste and contaminant species such as highly radioactive fission products are generally retained in the aqueous phase flow which forms an aqueous waste stream known as the raffinate.
  • Neptunium is an element which contaminates the extracted uranium and plutonium and further treatment is required of the stream into which uranium and plutonium are extracted (or subsequently after the uranium and plutonium have been separated) in order to separate contaminant neptunium ions.
  • a facility to handle such post-extraction treatment is expensive to design and construct.
  • a method of treating a liquid containing radioactive species to separate radioactive waste or contaminant species contained in the liquid into a radioactive aqueous waste stream which method includes the step of treating the liquid with an aqueous vanadium (IV) containing solvent under conditions in which reduction of neptunium (VI) to neptunium (V) is promoted but reduction of neptunium (V) to neptunium ( IN) is inhibited whereby the concentration of neptunium present as neptunium (V) in the liquid is increased by the treatment and the neptunium (V) is thereafter removed in the radioactive waste stream.
  • IV aqueous vanadium
  • the liquid from which the radioactive waste or contaminant species is to be separated may be an aqueous or mainly aqueous solution in which the radioactive waste or contaminant species are contained together with species to be separated.
  • the liquid may comprise an acidic solution containing actinide species to be extracted from the acidic solution and re-cycled.
  • the actinide species may comprise uranium and plutonium species.
  • Such actinides may be extracted in a known way by contacting the aqueous liquid with an organic extractant liquid. Tributyl phosphate which is widely used in the prior art may be used as such an extractant liquid.
  • a method of reprocessing spent nuclear fuel comprises dissolving the fuel in a strong acid solvent, contacting an aqueous flow containing the acid solution so formed with an organic extractant fluid to extract actinides comprising uranium and plutonium and forming a radioactive aqueous waste stream from the aqueous acidic flow from which the uranium and plutonium have been extracted, the aqueous acidic flow being contacted before or during contact with the organic extractant fluid with an aqueous vanadium (IV) containing solvent to bring about the aforementioned conversion of neptunium (VI) to neptunium (V).
  • Neptunium (VI) and neptunium (IV) ions are both soluble in organic solvents such as tributyl phosphate (TBP) optionally containing one or more additives, eg odourless kerosene (OK) which, as mentioned above, is widely used in the prior art as an extractant solvent for extraction of actinides such as uranium and plutonium from an acidic solution. Consequently, these species are likely to cause contamination of the organic solution into which the uranium and plutonium are extracted.
  • neptunium (V) ions are relatively insoluble in such solvents. By converting neptunium species to neptunium (V) in accordance with the present invention the contamination of the extractant solution may be reduced or eliminated thereby reducing the need for post-extraction treatment of the organic extractant solution.
  • the vanadium (IV) may be present in an aqueous solution which includes for example VOSO4.
  • the conditions inhibiting the reduction of Np(V) to Np(IV) may comprise one or more of the following: a) controlling the acidity.
  • the rate of reduction of Np(VI) is inversely proportional to acidity and the reduction of Np(V) is directly proportional to acidity; the reduction of Np(VI) is promoted at lower acidities and the reduction of Np(V) is diminished at lower acidities.
  • any Np(IV) produced can be rendered inextractable into TBP/OK by reacting it with a complexing ligand to form a complex that will not extract. Np(IV) thus remains in the aqueous phase as this complex.
  • Np(V) can be reduced by V(IV) to Np(IV) . This reduction is not expected according to known theory. Therefore, we have found surprisingly that inhibition of the reduction of Np(V) to Np(IV) by V(IV) is desirable to maximise conversion of Np species to Np(V) and thereby retain neptunium in a valency state which will not readily be extracted into an organic phase.
  • Figure 1 is a diagrammatic flowsheet illustrating the steps in an extraction process embodying the present invention.
  • Figure 1 illustrates an example of the Purex process for the reprocessing of spent nuclear fuel, the process incorporating the improvement provided by the present invention.
  • single headed arrows represent flow of aqueous liquid and double headed arrows represent flow of organic extractant solvent.
  • Spent fuel comprising uranium together with plutonium and other actinides and fission products such as technetium are dissolved in a concentrated nitric acid solution which is admitted at an inlet 1 to an extractor system 5.
  • An aqueous flow is admitted at an inlet 2 to a scrubber system 3.
  • the scrubber system 3 is coupled to an extractor system 5 and the aqueous flow from the scrubber system 3 is admitted via an inlet 8 to the extractor system 5 where it is mixed with the acid solution containing the dissolved fuel components.
  • Organic extractant solvent eg 30% by volume TBP/OK is admitted via an inlet 7 to the extractor system 5 and flows from the extractor system 5 to the scrubber system 3 via an inlet 9.
  • the extractor system 5 and the scrubber system 3 are connected in a countercurrent flow configuration.
  • the extractor system 5 and the scrubber system 3 each comprise a series of contacting and separation stages in which the organic solvent is successively contacted with and separated from the aqueous flow including the acid solution from the inlet 1.
  • Uranium and plutonium in the acid solution which is mixed into the aqueous flow in the separator system 5 are thereby progressively extracted into the organic solvent.
  • the contacting and separation stages may for example comprise known mixer-settler stages or known pulsed column mixing and separation stages.
  • the output of the separator system 5 comprises a waste aqueous stream known as the raffinate which leaves the separator system via an outlet 4.
  • the organic solution containing U and Pu is transferred via a conditioning stage (not shown) wherein Pu is reduced to Pu (III) which is insoluble in organic solvent from the scrubber system 3. It is delivered via a line 10 to form the inlet to a further scrubber system 11 coupled to a further extractor system 12.
  • An aqueous flow is admitted to the scrubber system 11 at an inlet 13 and is passed via a line 14 to the extractor system 12 which it leaves as an exit stream at an outlet 15.
  • An organic extractant solvent eg 30% TBP/OK
  • the respective aqueous and organic phase flows in the systems 11 and 12 are arranged in countercurrent flow configuration.
  • the aqueous flow is contacted by and separated from the organic solvent in the systems 11 and 12 in a series of contactor/separator stages as in the systems 3 and 5.
  • the organic extractant solvent progressively removes uranium from the aqueous phase flow in the systems 11, 12 and this is subsequently recovered into the aqueous phase by backwashing from the exit stream leaving via the outlet 18 and recovery into a solid product by thermal denitration.
  • Plutonium remains in the aqueous flow because as Pu(III) it is insoluble in the organic stream and is in the exit stream at the outlet 15 from which it is subsequently recovered, eg by known precipitation using an oxalate.
  • Neptunium is a contaminant in the acid solution admitted to the separator system 5 via the inlet 1. In the prior art this element is extracted with uranium and plutonium into the organic phase stream passing through the line 10 to the scrubber 11 and a post separation extraction facility would be required to extract Np from the exit organic stream at the outlet 18.
  • an aqueous solution containing vanadium (IV) ions eg VOSO4, ⁇ s added to the aqueous flow passing between the scrubber system 3 and extractor system 5, eg by addition at the inlet 2.
  • one or more of the steps described above is taken to inhibit further reduction of Np(V) to Np(IV).
  • Neptunium ions in the acid solution added to the aqueous flow in the extractor system 5 are thereby controlled to be in the valency 5 state and are not therefore extracted by the organic extractant solvent admitted to the systems 5 and 3 via the inlets 7 and 9.
  • neptunium ions remain in the aqueous phase in the extractor system 5 and are extracted in the raffinate extracted at the outlet 4 thereby avoiding the need for a post-separation stage for neptunium extraction to be applied to the uranium containing stream extracted via the outlet 18.

Abstract

A method of treating a liquid containing radioactive species to separate radioactive waste or contaminant species contained in the liquid into a radioactive aqueous waste stream. The method includes the step of treating the liquid with an aqueous vanadium (IV) containing solvent under conditions in which reduction of neptunium (VI) to neptunium (V) is promoted and reduction of neptunium (V) to neptunium (IV) is inhibited. The concentration of neptunium present as neptunium (V) in the liquid is increased by the treatment and the neptunium (V) is thereafter removed in the radioactive waste stream.

Description

THE TREATMENT OF LIQUIDS
The present invention relates to the treatment of liquids. In particular, it relates to the treatment of liquids containing radioactive species to separate radioactive waste or contaminant species contained therein.
In the so-called Purex process for the reprocessing of spent nuclear fuel, the spent fuel is dissolved in a strong acid, eg concentrated nitric acid, which is added to an aqueous phase flow which is contacted by an organic extractant solvent such as tributyl phosphate to extract recyclable uranium and plutonium ions. Radioactive waste and contaminant species such as highly radioactive fission products are generally retained in the aqueous phase flow which forms an aqueous waste stream known as the raffinate. Neptunium is an element which contaminates the extracted uranium and plutonium and further treatment is required of the stream into which uranium and plutonium are extracted (or subsequently after the uranium and plutonium have been separated) in order to separate contaminant neptunium ions. A facility to handle such post-extraction treatment is expensive to design and construct.
According to the present invention there is provided a method of treating a liquid containing radioactive species to separate radioactive waste or contaminant species contained in the liquid into a radioactive aqueous waste stream, which method includes the step of treating the liquid with an aqueous vanadium (IV) containing solvent under conditions in which reduction of neptunium (VI) to neptunium (V) is promoted but reduction of neptunium (V) to neptunium ( IN) is inhibited whereby the concentration of neptunium present as neptunium (V) in the liquid is increased by the treatment and the neptunium (V) is thereafter removed in the radioactive waste stream. The liquid from which the radioactive waste or contaminant species is to be separated may be an aqueous or mainly aqueous solution in which the radioactive waste or contaminant species are contained together with species to be separated. For example, the liquid may comprise an acidic solution containing actinide species to be extracted from the acidic solution and re-cycled. The actinide species may comprise uranium and plutonium species. Such actinides may be extracted in a known way by contacting the aqueous liquid with an organic extractant liquid. Tributyl phosphate which is widely used in the prior art may be used as such an extractant liquid.
In a particular form of the present invention a method of reprocessing spent nuclear fuel comprises dissolving the fuel in a strong acid solvent, contacting an aqueous flow containing the acid solution so formed with an organic extractant fluid to extract actinides comprising uranium and plutonium and forming a radioactive aqueous waste stream from the aqueous acidic flow from which the uranium and plutonium have been extracted, the aqueous acidic flow being contacted before or during contact with the organic extractant fluid with an aqueous vanadium (IV) containing solvent to bring about the aforementioned conversion of neptunium (VI) to neptunium (V).
Neptunium (VI) and neptunium (IV) ions are both soluble in organic solvents such as tributyl phosphate (TBP) optionally containing one or more additives, eg odourless kerosene (OK) which, as mentioned above, is widely used in the prior art as an extractant solvent for extraction of actinides such as uranium and plutonium from an acidic solution. Consequently, these species are likely to cause contamination of the organic solution into which the uranium and plutonium are extracted. However, neptunium (V) ions are relatively insoluble in such solvents. By converting neptunium species to neptunium (V) in accordance with the present invention the contamination of the extractant solution may be reduced or eliminated thereby reducing the need for post-extraction treatment of the organic extractant solution.
In the method according to the present invention the vanadium (IV) may be present in an aqueous solution which includes for example VOSO4.
The conditions inhibiting the reduction of Np(V) to Np(IV) may comprise one or more of the following: a) controlling the acidity. The rate of reduction of Np(VI) is inversely proportional to acidity and the reduction of Np(V) is directly proportional to acidity; the reduction of Np(VI) is promoted at lower acidities and the reduction of Np(V) is diminished at lower acidities. b) by controlling the vanadium present. Reducing the initial concentration of V(IV) possibly down to a stoichiometric (1:1 ratio) amount; excess V(IV) will drive the reaction towards Np(IV). Addition of V(V) solution may not be effective since it may promote the reoxidation of Np(V) back to Np(VI). c) in short residence time contactors (eg centrifuges) the effect of the slow reduction of Np(V) to Np(IV) will be diminished. d) any Np(IV) produced can be rendered inextractable into TBP/OK by reacting it with a complexing ligand to form a complex that will not extract. Np(IV) thus remains in the aqueous phase as this complex.
We have found by experimental analysis that Np(V) can be reduced by V(IV) to Np(IV) . This reduction is not expected according to known theory. Therefore, we have found surprisingly that inhibition of the reduction of Np(V) to Np(IV) by V(IV) is desirable to maximise conversion of Np species to Np(V) and thereby retain neptunium in a valency state which will not readily be extracted into an organic phase. An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic flowsheet illustrating the steps in an extraction process embodying the present invention.
Figure 1 illustrates an example of the Purex process for the reprocessing of spent nuclear fuel, the process incorporating the improvement provided by the present invention. In Figure 1 single headed arrows represent flow of aqueous liquid and double headed arrows represent flow of organic extractant solvent.
Spent fuel comprising uranium together with plutonium and other actinides and fission products such as technetium are dissolved in a concentrated nitric acid solution which is admitted at an inlet 1 to an extractor system 5. An aqueous flow is admitted at an inlet 2 to a scrubber system 3. The scrubber system 3 is coupled to an extractor system 5 and the aqueous flow from the scrubber system 3 is admitted via an inlet 8 to the extractor system 5 where it is mixed with the acid solution containing the dissolved fuel components. Organic extractant solvent eg 30% by volume TBP/OK is admitted via an inlet 7 to the extractor system 5 and flows from the extractor system 5 to the scrubber system 3 via an inlet 9. The extractor system 5 and the scrubber system 3 are connected in a countercurrent flow configuration. The extractor system 5 and the scrubber system 3 each comprise a series of contacting and separation stages in which the organic solvent is successively contacted with and separated from the aqueous flow including the acid solution from the inlet 1. Uranium and plutonium in the acid solution which is mixed into the aqueous flow in the separator system 5 are thereby progressively extracted into the organic solvent. The contacting and separation stages may for example comprise known mixer-settler stages or known pulsed column mixing and separation stages.
The output of the separator system 5 comprises a waste aqueous stream known as the raffinate which leaves the separator system via an outlet 4. This contains a mixture of highly radioactive fission products and other contaminants. These contaminants are subsequently extracted in a concentrated solid form and immobilised and encapsulated, eg by a known vitrification process.
The organic solution containing U and Pu is transferred via a conditioning stage (not shown) wherein Pu is reduced to Pu (III) which is insoluble in organic solvent from the scrubber system 3. It is delivered via a line 10 to form the inlet to a further scrubber system 11 coupled to a further extractor system 12. An aqueous flow is admitted to the scrubber system 11 at an inlet 13 and is passed via a line 14 to the extractor system 12 which it leaves as an exit stream at an outlet 15. An organic extractant solvent (eg 30% TBP/OK) is admitted via an inlet 16 to the extractor system 12 and flows via a line 17 to the scrubber system 11 which it leaves via an outlet 18. The respective aqueous and organic phase flows in the systems 11 and 12 are arranged in countercurrent flow configuration. The aqueous flow is contacted by and separated from the organic solvent in the systems 11 and 12 in a series of contactor/separator stages as in the systems 3 and 5. The organic extractant solvent progressively removes uranium from the aqueous phase flow in the systems 11, 12 and this is subsequently recovered into the aqueous phase by backwashing from the exit stream leaving via the outlet 18 and recovery into a solid product by thermal denitration. Plutonium remains in the aqueous flow because as Pu(III) it is insoluble in the organic stream and is in the exit stream at the outlet 15 from which it is subsequently recovered, eg by known precipitation using an oxalate. Neptunium is a contaminant in the acid solution admitted to the separator system 5 via the inlet 1. In the prior art this element is extracted with uranium and plutonium into the organic phase stream passing through the line 10 to the scrubber 11 and a post separation extraction facility would be required to extract Np from the exit organic stream at the outlet 18.
In accordance with the present invention, an aqueous solution containing vanadium (IV) ions, eg VOSO4, ^s added to the aqueous flow passing between the scrubber system 3 and extractor system 5, eg by addition at the inlet 2. In addition one or more of the steps described above is taken to inhibit further reduction of Np(V) to Np(IV). Neptunium ions in the acid solution added to the aqueous flow in the extractor system 5 are thereby controlled to be in the valency 5 state and are not therefore extracted by the organic extractant solvent admitted to the systems 5 and 3 via the inlets 7 and 9. The neptunium ions remain in the aqueous phase in the extractor system 5 and are extracted in the raffinate extracted at the outlet 4 thereby avoiding the need for a post-separation stage for neptunium extraction to be applied to the uranium containing stream extracted via the outlet 18.

Claims

1. A method of treating a liquid containing radioactive species to separate radioactive waste or contaminant species contained in the liquid into a radioactive aqueous waste stream, which method includes the step of treating the liquid with an aqueous vanadium (IV) containing solvent under conditions in which reduction of neptunium (VI) to neptunium (V) is promoted but reduction of neptunium (V) to neptunium (IV) is inhibited whereby the concentration of neptunium present as neptunium (V) in the liquid is increased by the treatment and the neptunium (V) is thereafter removed in the radioactive waste stream.
2. A method as in Claim 1 and wherein the liquid from which the radioactive waste or contaminant species is to be separated comprises an aqueous or mainly aqueous solution in which the radioactive waste or contaminant species are contained together with species to be separated.
3. A method as in Claim 2 and wherein the said liquid comprises an acidic solution containing actinide species to be extracted from the acidic solution and re-cycled.
4. A method as in Claim 3 and which comprises a method of reprocessing spent nuclear fuel which comprises dissolving the fuel in a strong acid solvent, contacting an aqueous flow containing the acid solution so formed with an organic extractant fluid to extract actinides comprising uranium and plutonium and forming a radioactive aqueous waste stream from the aqueous acidic flow from which the uranium and plutonium have been extracted, the aqueous acidic flow being contacted before or during contact with the organic extractant fluid with an aqueous vanadium (IV) containing solvent to bring about the aforementioned conversion of neptunium (VI) to neptunium (V) .
PCT/GB1995/002357 1994-10-05 1995-10-05 The treatment of liquids WO1996011477A1 (en)

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GB9420080A GB9420080D0 (en) 1994-10-05 1994-10-05 The treatment of liquids

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999023668A1 (en) * 1997-10-31 1999-05-14 British Nuclear Fuels Plc Nuclear fuel reprocessing
US6025874A (en) * 1995-07-11 2000-02-15 Ultrak, Inc. Video multiplexer
WO2000013187A1 (en) * 1998-08-28 2000-03-09 British Nuclear Fuels Plc Nuclear fuel reprocessing including reduction of np(vi) to np(v) with an oxime
US6444182B1 (en) 1998-08-28 2002-09-03 British Nuclear Fuels Plc Nuclear fuel reprocessing using hydrophilic substituted hydroxylamines

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FR2554434A1 (en) * 1983-11-04 1985-05-10 Commissariat Energie Atomique Process for the treatment of acid nitric aqueous effluents containing oxalic acid, usable in particular for treating the mother liquors from the precipitation of plutonium oxalate
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FR2554434A1 (en) * 1983-11-04 1985-05-10 Commissariat Energie Atomique Process for the treatment of acid nitric aqueous effluents containing oxalic acid, usable in particular for treating the mother liquors from the precipitation of plutonium oxalate
EP0233124A2 (en) * 1986-02-13 1987-08-19 Commissariat A L'energie Atomique Method for dosing neptunium using absorption spectrophotometry

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Title
CHEMICAL ABSTRACTS, vol. 94, no. 10, 9 March 1981, Columbus, Ohio, US; abstract no. 72268, KOLTUNOV ET AL: "INTERACTION OF ACTINIDES WITH VANADIUM IONS. II. KINETICS OF THE REDUCTION OF NEPTUNIUM (VI) BY VANADIUM (IV) IN A PERCHLORIC ACID SOLUTION IN THE PRESENCE OF GLYOXAL." *
CHEMICAL ABSTRACTS, vol. 94, no. 10, 9 March 1981, Columbus, Ohio, US; abstract no. 72269, KOLTUNOV: "INTERACTION OF ACTINIDES WITH VANADIUM IONS. III. KINETICS OF THE REDUCTION OR NEPTUNIUM (VI) BY VANADIUM (IV) IN A NITRIC ACID SOLUTION IN THE PRESENCE OF GLYOXAL." *
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6025874A (en) * 1995-07-11 2000-02-15 Ultrak, Inc. Video multiplexer
WO1999023668A1 (en) * 1997-10-31 1999-05-14 British Nuclear Fuels Plc Nuclear fuel reprocessing
WO2000013187A1 (en) * 1998-08-28 2000-03-09 British Nuclear Fuels Plc Nuclear fuel reprocessing including reduction of np(vi) to np(v) with an oxime
US6413482B1 (en) 1998-08-28 2002-07-02 British Nuclear Fuels Plc Method for reprocessing nuclear fuel by employing oximes
US6444182B1 (en) 1998-08-28 2002-09-03 British Nuclear Fuels Plc Nuclear fuel reprocessing using hydrophilic substituted hydroxylamines

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