EP0347625B1 - Procédé pour la séparation de technétium, de ruthénium et de palladium par des solutions de combustible nucléaire - Google Patents

Procédé pour la séparation de technétium, de ruthénium et de palladium par des solutions de combustible nucléaire Download PDF

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Publication number
EP0347625B1
EP0347625B1 EP19890109897 EP89109897A EP0347625B1 EP 0347625 B1 EP0347625 B1 EP 0347625B1 EP 19890109897 EP19890109897 EP 19890109897 EP 89109897 A EP89109897 A EP 89109897A EP 0347625 B1 EP0347625 B1 EP 0347625B1
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EP
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Prior art keywords
palladium
ruthenium
solution
nitric acid
technetium
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Expired - Lifetime
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EP19890109897
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German (de)
English (en)
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EP0347625A2 (fr
EP0347625A3 (en
Inventor
Hossein Ghafourian
Abdel Hadi Ali Dr. Sameh
Hans Joachim Prof. Dr. Ache
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Karlsruher Institut fuer Technologie KIT
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Kernforschungszentrum Karlsruhe GmbH
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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

Definitions

  • the invention relates to a process for separating the valuable substances technetium, ruthenium and palladium from material flows which arise during the reprocessing of irradiated nuclear fuel, the valuable substances being isolated by precipitation and ion exchange from a nitric acid containing the valuable substances and other fission / activation products.
  • Fission products are isotopes of chemical elements that arise when atoms of the nuclear fuel (uranium, plutonium) are split into two or three fragments. These isotopes can themselves be radioactive, but can also be inactive. Technetium, ruthenium and palladium belong to the group of fission products. Technetium mainly forms the isotope with the mass 99, which is weakly radioactive and therefore does not occur in nature and can therefore only be generated artificially by nuclear reactions.
  • the fission products ruthenium and palladium arise in nuclear reactors in large quantities, whereby both radioactive and non-radioactive isotopes are formed.
  • Fission ruthenium contains about 3% of the isotope Ru-106, which has a half-life of about 1 year and decays into inactive palladium (Pd-106). Fission palladium is very weakly radioactive due to its Pd-107 content. However, this radioactivity does not significantly limit the usability for technical purposes.
  • the irradiated nuclear fuel is dissolved in boiling semi-concentrated nitric acid. The majority of the nuclear fuels and the fission and activation products go into solution.
  • a small remainder of the irradiated nuclear fuel remains in the undissolved form in the dissolver. This residue is known as feed sludge. It contains significant amounts of molybdenum, zirconium, technetium and precious metals.
  • the loaded beds are preferably incinerated and the valuable materials are isolated from the ashes.
  • the chelating agents can contaminate the solution which has been freed from the valuable substances and in this way can severely disrupt the removal of further valuable substances or the conditioning of the remaining ingredients.
  • the carbon beds represent a significant hazard potential. They are burned after loading, whereby radioactive components are released as gases or aerosols and must be retained by an effective exhaust gas cleaning system with the help of scrubbers and filters. Washing liquids and filters must be disposed of as secondary waste.
  • the object of the invention is to selectively separate the valuable materials technetium, ruthenium and palladium from acidic solutions of irradiated nuclear fuel and with high efficiency.
  • the separation of these valuable substances should not cause any additional problems in the further treatment of the radioactive substances; in particular, only substances should be used which do not contaminate the solution freed from the valuable substances or which can be removed by simple measures such. B. remove by heating or extracting the solution. Easily flammable substances should not be used.
  • the process should be simple to carry out, with as little secondary waste as possible.
  • the process according to the invention can be carried out with all nitric acid solutions which are produced during the reprocessing process and which contain technetium, ruthenium and palladium.
  • Feed clarification sludge is a preferred source of these valuable substances because it contains the valuable substances in a concentrated form.
  • the feed sludge can be brought into solution by treating it in a manner known per se with reducing gases such as C0 or H2 and annealing it with carbonates.
  • reducing gases such as C0 or H2
  • the residue on ignition is taken up with 3-7 molar nitric acid and the solution is adjusted to 1 mol HN03 / l.
  • Rhodium remains behind as Rh203.
  • the solution freed from solid Rh203 forms the stock solution of the process according to the invention which, in addition to the valuable materials technetium, ruthenium and palladium, depending on the origin and pretreatment of the irradiated nuclear fuel, also varying amounts of the elements Pu, U, Am, Mo, Zr, Ce and other fission and may contain activation products.
  • Diethyl thiourea (DETH) is added to the stock solution in solid form or as an aqueous solution.
  • the amount of DETH depends on the amount of palladium and ruthenium in the stock solution. 4 moles of DETH are added per mole of palladium and an additional 6 moles of DETH are added per mole of ruthenium. Palladium selectively forms an insoluble precipitate with the DETH reagent, which contains more than 99% of the palladium present are. Spectrophotometric studies allow the assumption that it is polymeric Pd-DETH complexes.
  • the precipitate containing palladium is separated off in a customary manner and roasted at about 500.degree. This forms Pd0, which can be reduced to metal by annealing at 900 ° C.
  • the Pd precipitate filtrate is heated to a temperature of about 70 ° C for about 30 minutes to accelerate complexation of the DETH with ruthenium.
  • the cooled solution is passed through a strongly acidic cation exchanger.
  • the Ru (NO) -DETH compounds which are only present in cationic form, are quantitatively retained on the adsorber together with the Tc02+ ions present in the medium in the tetravalent state, while the accompanying impurities are only partially adsorbed and by washing the column with about 2-molar HNO3 can be desorbed again.
  • the strongly acidic cation exchanger AG 50 W-X2 (Fa. BiO-RAD Laboratories GmbH, Kunststoff) proved to be particularly efficient in terms of capacity and sorption kinetics; it consists of a macroporous co-polymer of polystyrene divinylbenzene with 2% crosslinking.
  • the technetium is selectively and quantitatively eluted.
  • the elution is preferably carried out with a solution of about 0.1 - 1 mol H202 / l and 0.1 - 1 mol HNO3 / l.
  • Technetium is present as pertechnetate after elution.
  • Ruthenium is then eluted; preferably 6-8 molar HN03 is used as the eluent.
  • An essential advantage of the process according to the invention is that, in addition to the nitric acid which is in any case necessary for the dissolution of irradiated nuclear fuel, only chemicals are used which can be removed from the solution freed from the valuable substances by simple boiling or extraction. Therefore, the further treatment of these solutions is not made difficult.
  • the process can be integrated into the process diagram of the reprocessing without the reprocessing process having to be changed.
  • the method according to the invention is characterized by a high effectiveness;
  • the high loading levels that can be achieved allow the construction of compact, easy-to-use systems.
  • the implementation examples are based on a stock solution which is obtained from feed sludge by carbonate digestion.
  • rhodium remains behind.
  • An inactive simulate was used for the feed sewage sludge, which is based on published data on the composition of the feed sewage sludge (K. Naito et al, Recovery of Noble Metals from Insoluble Residue of Spent Fuel, J. Nucl. Sc. And Tech., 23 (6) , pp. 540-549 (June 1986); H. Kleykamp, composition of residues from the dissolution of irradiated LWR- (U, PU) 02 with recycled Pu, atomic economy, July 1982).
  • the inactive simulate was carried with radioactive isotopes of the corresponding elements.
  • Isotope 239 was used for plutonium; the rare earths are represented by the element cerium.
  • Table 1 shows the average composition of the feed sludge in% by weight.
  • Tables 2 and 3 show the molar concentrations of the individual elements in the stock solution used.
  • Table 2 (Experiment 1) element Concentration (mol / l) Ru / external nuclide ratio Decontamination factor DF Ru 5 x 10 ⁇ 3 - 3 x 103 U 5 x 10 ⁇ 4 10th 4.6 x 102 Pu 1.25 x 10 ⁇ 5 400 > 1 x 103 At the 3 x 10 ⁇ 6 333 > 6 x 102 Mon 1.87 x 10 ⁇ 3 2.67 > 1 x 106 Tc 3.75 x 10 ⁇ 4 13.33 1 x 104 Pd 1 x 10 ⁇ 3 5 > 99 Zr 3.75 x 10 ⁇ 5 133.33 6.25 x 102 Ce 1.25 x 10 ⁇ 4 40 5 x 104 (Experiment 2) element Concentration (mol / l) Ru / external nuclide ratio Decontamination factor DF Ru 1 x 10 ⁇ 2 - 2.8 x 103 U 1 x 10 ⁇ 3 10th 5.1 x 102 Pu 2.5 x
  • the decontamination factor DF indicates the proportion of the elements removed when carrying out the method according to the invention.
  • the valuable materials ruthenium, technetium and palladium are separated with decontamination factors from 2800 - 3000 or 10000 to 13000 or> 99.
  • the separated materials are only very slightly contaminated by the undesired fission products and actinides, as can be seen from the decontamination factors of these elements.
  • a 1 molar nitric acid solution was used as the stock solution.
  • the element concentrations for test 1 are shown in table 2, for test 2 in table 3.
  • the organic complexing agent N, N′-diethylthiourea was added to the stock solutions at room temperature. 4 moles of DETH were added per mole of palladium present in the stock solution and 6 moles of DETH were added per mole of ruthenium present in the stock solution. After about 15 minutes, more than 99% of the palladium has precipitated as a Pd-DETH complex. The residue was separated and the solution freed from the residue was heated in a thermostated water bath at 70 ° C. for 30 minutes.
  • the ruthenium nitrosyl nitrate complexes which are present in different Ru values, are quantitatively converted into the double and triple positively charged ruthenium nitrosyl diethyl urea complexes, while technetium, which originally existed as pertechnetrate, is reduced to Tc02+.
  • the column was washed with 4-5 column volumes of 2-molar HNO3, the interfering substances (Zr, Ce, U, Pu, Am, Mo) partially retained on the column being removed.
  • the column was then oxidized with 4 column volumes of an aqueous solution, each containing HNO3 and H202 in a concentration of 0.5 mol / l, the technetium being released as the pertechnetrate.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Claims (7)

  1. Procédé de séparation des matières de valeur de technétium, ruthénium et palladium à partir de flux de matières, qui prennent naissance lors du retraitement de combustible nucléaire irradié, les matières de valeur étant séparées par précipitation et échange d'ions à partir d'une solution de base d'acide nitrique, contenant les matières de valeur et autres produits de fission et d'activation, caractérisé par les opérations suivantes :
    a) addition de diéthylthiourée (DETH) à la solution de base, dans laquelle le palladium précipite sélectivement, et séparation du dépôt,
    b) introduction de la solution libérée du palladium dans un lit d'un échangeur cationique fortement acide pour séparer le technétium et le ruthénium,
    c) lavage de l'échangeur cationique avec de l'acide nitrique dilué, de préférence sensiblement 2 fois molaire,
    d) élution sélective oxydante du technétium avec une solution d'acide nitrique, qui contient un oxydant,
    e) élution sélective du ruthénium à l'aide d'acide nitrique concentré, de préférence 6 - 8 fois molaire.
  2. Procédé selon la revendication 1, caractérisé en ce qu'on ajoute par mole de palladium existant dans la solution de base, environ 4 moles de DETH et en plus, par mole de ruthénium existant dans la solution de base, environ 6 moles de DETH.
  3. Procédé selon la revendication 1, caractérisé en ce que comme échangeur cathionique fortement acide, on utilise un co-polymère macroporeux de polystyrène divinylbenzène ayant 2 - 8 pour-cent de réticulation, de préférence 2 % de réticulation.
  4. Procédé selon la revendication 1, caractérisé en ce que pour l'élution oxydante sélective du technétium, on utilise une solution d'acide nitrique contenant du peroxyde d'hydrogène, solution contenant aussi bien du peroxyde d'hydrogène que de l'acide nitrique dans la zone de concentrations 0,05 - 3 mole/litre, de préférence 0,1 - 1 mole/litre.
  5. Procédé selon la revendication 1, caractérisé en ce que la solution de base est produite à partir des boues de curage de réaction, la plus grande partie des boues de curage de réaction étant amenée, en solution, par une dissolution de carbonate et addition d'acide nitrique et la solution étant séparée par de l'oxyde de rhodium non soluble.
  6. Procédé selon la revendication 1, caractérisé en ce que le précipité se formant à partir de DETH et du palladium est transformé à environ 500°C en oxyde de palladium et du palladium métallique est produit à partir de l'oxyde de palladium par calcination à environ 900°C.
  7. Procédé selon la revendication 1, caractérisé en ce que la solution libérée du palladium est chauffée à une température d'environ 70°C avec DETH pendant environ 30 minutes pour accélérer la formation de complexes du ruthénium.
EP19890109897 1988-06-24 1989-06-01 Procédé pour la séparation de technétium, de ruthénium et de palladium par des solutions de combustible nucléaire Expired - Lifetime EP0347625B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3821295 1988-06-24
DE19883821295 DE3821295A1 (de) 1988-06-24 1988-06-24 Verfahren zur abtrennung von technetium, ruthenium und palladium aus kernbrennstoff-loesungen

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EP0347625A2 EP0347625A2 (fr) 1989-12-27
EP0347625A3 EP0347625A3 (en) 1990-02-28
EP0347625B1 true EP0347625B1 (fr) 1993-10-20

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DE (1) DE3821295A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5886154A (en) * 1997-06-20 1999-03-23 Lebing; Wytold R. Chromatographic method for high yield purification and viral inactivation of antibodies
CN113406114B (zh) * 2021-04-28 2022-10-21 中国辐射防护研究院 一种气溶胶中Pu、Am、U含量的联合分析方法
FR3133390A1 (fr) 2022-03-10 2023-09-15 Commissariat A L'energie Atomique Et Aux Energies Alternatives Procédé de purification du ruthénium vis-à-vis du technétium et d’impuretés métalliques en solution aqueuse d’acide nitrique

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3848048A (en) * 1973-07-12 1974-11-12 Atomic Energy Commission Recovery of fission-produced technetium,palladium,rhodium and ruthenium
DE2849050C2 (de) * 1978-11-11 1986-04-17 Kernforschungsanlage Jülich GmbH, 5170 Jülich Verfahren zur Aufarbeitung von ammoniumnitrathaltigen Abfalllösungen der Kerntechnik
DD145909A1 (de) * 1979-09-11 1981-01-14 Brunhilde Gorski Verfahren zur gewinnung von techne ium und palladium aus kernbrennstoffwiederaufbereitungs oesungen
FR2485510A1 (fr) * 1980-06-26 1981-12-31 Commissariat Energie Atomique Procede d'extraction du palladium a partir de solutions nitriques et son application a la separation palladium-ruthenium
DD154970A2 (de) * 1980-09-10 1982-05-05 Brunhilde Gorski Verfahren zur gewinnung von technetium und palladium aus kernbrennstoffwiederaufbereitungsloesungen
DE3243840A1 (de) * 1982-11-26 1984-05-30 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Verfahren zur denitrierung waessriger, salpetersaurer, salzhaltiger abfall-loesungen

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EP0347625A2 (fr) 1989-12-27
EP0347625A3 (en) 1990-02-28
DE3821295A1 (de) 1989-12-28
DE3821295C2 (fr) 1991-01-24

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