EP0036359B1 - Verfahren zur Dekontaminierung eines Plutonium enthaltenden organischen Lösungsmittels - Google Patents

Verfahren zur Dekontaminierung eines Plutonium enthaltenden organischen Lösungsmittels Download PDF

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Publication number
EP0036359B1
EP0036359B1 EP81400365A EP81400365A EP0036359B1 EP 0036359 B1 EP0036359 B1 EP 0036359B1 EP 81400365 A EP81400365 A EP 81400365A EP 81400365 A EP81400365 A EP 81400365A EP 0036359 B1 EP0036359 B1 EP 0036359B1
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EP
European Patent Office
Prior art keywords
plutonium
acid
organic solvent
process according
solution
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Expired
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EP81400365A
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English (en)
French (fr)
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EP0036359A1 (de
Inventor
Richard Fitoussi
Claude Musikas
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • 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

Definitions

  • the present invention relates to a plutonium decontamination process for an organic solvent, in particular a spent organic solvent such as tributyl phosphate, which has been used for the uranium-plutonium separation during the reprocessing of irradiated nuclear fuels.
  • an organic solvent in particular a spent organic solvent such as tributyl phosphate, which has been used for the uranium-plutonium separation during the reprocessing of irradiated nuclear fuels.
  • the process of the invention specifically relates to a process for decontaminating plutonium from an organic solvent which makes it possible to satisfactorily recover the plutonium contained in this solvent.
  • This process for decontaminating an organic solvent from the plutonium which it contains consists in adding to said organic solvent a reducing agent soluble in this organic solvent, and it is characterized in that the reducing agent consists of a dialkyldithiophosphoric acid, the organic solvent containing said reducing agent is brought into contact with an acidic aqueous solution and said aqueous solution containing Pu is then separated from the decontaminated organic solvent.
  • the reducing agent consists of a dialkyldithiophosphoric acid
  • a dialkyl dithiophosphoric acid is used, the alkyl radicals of which have 1 to 4 carbon atoms, for example diethyldithiophosphoric acid or dibutyldithiophosphoric acid.
  • the process as characterized above advantageously takes advantage of the fact that by using a dialkyldithiophosphoric acid as reducing agent, the plutonium present in this solvent can be reduced under good conditions and then re-extracted in an acidic aqueous solution such as nitric solution.
  • dialkyldithiophosphoric acid has certain advantages : it is soluble in the organic solvent while the aromatic organic compounds are divided between the aqueous phase and the organic phase, which leads to poorer performance; moreover, the reducing agent of the invention can be used in the presence of nitric acid, which is not the case for dialkylhydroquinones which are destroyed by oxidation in the presence of nitric acid.
  • dialkyldithiophosphoric acids which are reducing agents as effective as those currently used, it is possible to reduce the plutonium in the organic phase and re-extract it in an aqueous phase constituted by an acid solution.
  • the acidic aqueous solution is a solution of mineral acid such as nitric acid, hydrochloric acid, sulfuric acid.
  • the acidity of this solution can vary over a wide range because the kinetics of plutonium re-extraction is practically unaffected by the acidity of the aqueous phase.
  • the reducing agent is diethyldithiophosphoric acid
  • an acid solution preferably having an acidity at least equal to 0.5 N is preferably used since, in this case, the reducing agent is slightly soluble in a weakly acid medium.
  • the spent organic solvent containing the reducing agent is brought into contact with the acidic aqueous solution at a temperature above 10 ° C., preferably between 10 and 60 ° C., since the re-extraction rate increases with temperature. .
  • the decontaminated solvent is preferably subjected to an additional purification treatment in order to remove the excess agent reducing agent and the oxidation products formed in the solvent from this reducing agent.
  • this purification treatment is advantageously carried out by bringing the decontaminated organic solvent into contact with a basic solution such as sodium carbonate solution.
  • washing with a 0.6 M sodium carbonate solution with a stirring time of 5 min, at room temperature, makes it possible to remove more than 99% of the diethyldithiophosphoric acid and more than 90% dibutyldithiophosphoric acid present in an organic solvent.
  • this elimination is ensured by carrying out the basic treatment for purifying the decontaminated solvent, in the presence of an oxidizing agent such as sodium nitrite, which is added to the basic solution.
  • the disulfide is converted into products soluble in the aqueous phase, which also makes it possible to eliminate, during the basic purification treatment of the decontaminated solvent, the oxidation products of dialkyldithiophosphoric acids.
  • This cycle is followed by a solvent regeneration treatment in a mixer-settler, a treatment which consists in successively washing the solvent with a 0.6 M sodium carbonate solution, a 1 N nitric acid solution and a NaOH solution. 1 N.
  • the solvent subjected to the decontamination treatment is removed before the regeneration treatment in a mixer-decanter.
  • the decontamination of the solvent is carried out by bringing 20 cm 3 of an aqueous solution of nitric acid to 20 cm 3 of spent organic solvent comprising an agent, with stirring by means of a rotating magnetic bar.
  • reducing agent consisting either of diethyldithiophosphoric acid having a purity of approximately 90%, or of dibutyldithiophosphoric acid having a purity of at least 95%.
  • the extraction is carried out in a device thermostatically controlled by water circulation, and the plutonium content of each of the phases is determined after decantation by alpha counting using a ZnS scintillator or an EMIA 2 type ionization chamber.
  • the partition coefficient D of the plutonium is evaluated, which corresponds to the ratio of the plutonium concentration of the organic phase to the plutonium concentration of the aqueous phase.
  • curves 1, 2 and 3 relate respectively to the re-extractions carried out with a concentration of diethyldithiophosphoric acid in the spent solvent of 5. 10-3 M, 10- 2 M and 2 ⁇ 10-2 M, and the curve 4 shows variations in the partition coefficient D of plutonium re-extraction conducted under the same conditions but in the absence of reducing agent.
  • diethyldithiophophosric acid is a very effective reducing agent since it only takes five minutes to re-extract 97% of the plutonium when the concentration of reducing agent in the organic phase is 2 ⁇ 10 -2 M at room temperature (23 ° C).
  • This example applies to the case where the temperature in the reprocessing installation is close to 30 ° C.
  • the operation is carried out without heating with a dibutyldithiophosphoric acid concentration of 5 - 10 - 3 M.
  • a plutonium partition coefficient equal to 0.003 is found (see FIG. 2) and we have eliminated solvent 99.7% of plutonium having used a volume of 0.05 N aqueous solution of nitric acid for a volume of solvent. This is then sent to the carbon regeneration unit.
  • the elimination of 99% of the dibutyldithiophosphoric acid requires two contacts of 5 min as in Example 2.
  • the plutonium content of the organic solvent treated in the three examples described is 20 mg / 1.
  • the process of the invention thus makes it possible to obtain satisfactory decontamination in plutonium of organic solvents, both acidic and basic. Also, it is of great interest for ensuring the decontamination in plutonium of the used organic solvents before the basic regeneration treatments, which makes it possible to avoid the formation of alkaline radioactive effluents.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Extraction Or Liquid Replacement (AREA)

Claims (11)

1. Verfahren zur Dekontaminierung eines organischen Lösungsmittels von enthaltenem Plutonium, durch Zusatz zu dem organischen Lösungsmittel von einem in dem organischen Lösungsmittel löslichen Reduktionsmittel, dadurch gekennzeichnet, daß das Reduktionsmittel aus einer Dialkyldithiophosphorsäure besteht, das organische Lösungsmittel, das dieses Reduktionsmittel enthält, mit einer wässrigen sauren Lösung in Kontakt gebracht wird und die wässrige Lösung, die das Pu enthält, anschließend von dem dekontaminierten organischen Lösungsmittel abgetrennt wird.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Dialkyldithiophosphorsäure Diethyldithiophosphorsäure ist.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Dialkyldithiophosphorsäure Dibutyldithiophosphorsäure ist.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die wässrige saure Lösung eine Lösung von Mineralsäure, wie Salpetersäure, Chlorwasserstoffsäure, Schwefelsäure ist.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die wässrige saure Lösung eine Acidität von 0,01 bis 1 N aufweist.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß man den Kontakt des -ias Reduktionsmittel enthaltenden organischen Lösungsmittels mit der wässrigen sauren Lösung bei einer Temperatur von 10 bis 60 °C durchführt.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß man das dekontaminierte organische Lösungsmittel anschließend reinigt, indem man es in Kontakt mit einer basischen Lösung bringt.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die basische Lösung eine Lösung von Natriumcarbonat ist.
9. Verfahren nach einem der Ansprüche 7 und 8, dadurch gekennzeichnet, daß man zu der basischen Lösung ein Oxidationsmittel fügt.
10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, daß das Oxidationsmittel Natriumnitrit ist.
11. Verfahren nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, daß das organische Lösungsmittel Tributylphosphat umfaßt.
EP81400365A 1980-03-13 1981-03-10 Verfahren zur Dekontaminierung eines Plutonium enthaltenden organischen Lösungsmittels Expired EP0036359B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8005626A FR2478363B1 (fr) 1980-03-13 1980-03-13 Procede de decontamination en plutonium d'un solvant organique
FR8005626 1980-03-13

Publications (2)

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EP0036359A1 EP0036359A1 (de) 1981-09-23
EP0036359B1 true EP0036359B1 (de) 1984-06-13

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EP81400365A Expired EP0036359B1 (de) 1980-03-13 1981-03-10 Verfahren zur Dekontaminierung eines Plutonium enthaltenden organischen Lösungsmittels

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US (1) US4404130A (de)
EP (1) EP0036359B1 (de)
JP (1) JPS56143999A (de)
DE (1) DE3164062D1 (de)
FR (1) FR2478363B1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4595529A (en) * 1984-03-13 1986-06-17 The United States Of America As Represented By The Department Of Energy Solvent wash solution
US4681705A (en) * 1985-10-15 1987-07-21 Carolina Power & Light Company Decontamination of radioactively contaminated liquids
US4855081A (en) * 1988-06-07 1989-08-08 Nutech, Inc. Method for decontaminating conventional plastic materials which have become radioactively contaminated, and articles
JPH0495899A (ja) * 1990-08-14 1992-03-27 Power Reactor & Nuclear Fuel Dev Corp 核燃料サイクルから発生する使用済溶媒の抽出分離方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2212611A1 (de) * 1972-12-28 1974-07-26 Commissariat Energie Atomique

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3580705A (en) * 1968-10-02 1971-05-25 Atomic Energy Commission Selective stripping of plutonium from organic extracts

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2212611A1 (de) * 1972-12-28 1974-07-26 Commissariat Energie Atomique

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Publication number Publication date
JPS56143999A (en) 1981-11-10
FR2478363B1 (fr) 1987-05-07
FR2478363A1 (fr) 1981-09-18
EP0036359A1 (de) 1981-09-23
DE3164062D1 (en) 1984-07-19
US4404130A (en) 1983-09-13

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