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WO2000003398A1 - Procede de traitement de dechets renfermant du technetium - Google Patents

Procede de traitement de dechets renfermant du technetium Download PDF

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Publication number
WO2000003398A1
WO2000003398A1 PCT/GB1999/002077 GB9902077W WO0003398A1 WO 2000003398 A1 WO2000003398 A1 WO 2000003398A1 GB 9902077 W GB9902077 W GB 9902077W WO 0003398 A1 WO0003398 A1 WO 0003398A1
Authority
WO
WIPO (PCT)
Prior art keywords
process according
metal
technetium
pertechnetate
column
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/GB1999/002077
Other languages
English (en)
Inventor
James Darcy Mckinney
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sellafield Ltd
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
Priority to AU45267/99A priority Critical patent/AU4526799A/en
Publication of WO2000003398A1 publication Critical patent/WO2000003398A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G99/00—Subject matter not provided for in other groups of this subclass
    • C01G99/006—Compounds containing a metal not provided for elsewhere in this subclass, with or without oxygen or hydrogen, and containing two or more other elements
    • 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
    • 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
    • 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 an aqueous medium containing pertechnetate.
  • Improvements are continually being sought in relation to the decontamination of byproducts of processes in the nuclear industry. It is particularly important to ensure the removal of contaminants, including radioactive species, from aqueous waste effluent streams.
  • the present invention is particularly suited to the removal of technetium from such effluent.
  • Technetium is found in the floc as the pertechnetate ion TcO " (Tc VII). This ion is very stable and mobile in solution, as consequently is very difficult to remove with the floc in the ultrafiltration process.
  • a number of alternative or additional techniques for recovering dissolved technetium-99 have been tried, for example, electrochemical ion exchange, seeded ultrafiltration, and bioreduction. However, these techniques are costly and consequently there is a need to look for more economic methods for the separation of technetium-99.
  • the present invention provides a process for the treatment of an aqueous medium comprising technetium in the form of dissolved pertechnetate, the process comprising bringing the medium into contact with a metal to thereby reduce the dissolved pertechnetate to at least one non-metallic technetium species of lower oxidation state.
  • the reduced species of technetium-99 are readily removed from solution.
  • reduction of Tc v ⁇ may give Tc v and/or Tc species, which are readily removed from solution, and which plate out upon the metal used for the reduction step, avoiding the need to filter the reduced solution.
  • the technetium is retained on the reducing metal, and at a later stage, as appropriate (for example when the reducing activity of the metal has fallen below a predetermined level), the technetium may be stripped off (for example using an acid such as nitric acid) and the reducing metal rejuvenated.
  • an acid such as nitric acid
  • the metal may be selected from one or more of the group comprising iron, zinc, gallium indium thallium, scandium, lanthanum, yttrium and actinium. However, preferably the metal is aluminium.
  • a further advantage of the process of the present invention is that pertechnetate is selectively reduced in preference to nitrate ions.
  • the process of the present invention may be used in conjunction with existing plant such as EARP, to selectively reduce TcO " in preference to the other species present in the floc, particularly nitrate NO 3 ⁇ .
  • the process works efficiently at pH values of between 10 and 11.5, these pH values being commonly found in EARP.
  • a key parameter in controlling reaction rate is the surface area of the metal. This can be controlled by selection of the physical form of the metal. Metal shot can be used as well as metal powder, metal wool and dendritic shaped particles. The size of these particles controls the surface area per unit volume and therefore the reaction rate. The smaller the particles, the larger the surface area and the faster the reaction rate.
  • temperature may be controlled (heating or cooling) in order to vary the reaction rate. This property is useful to accelerate slow reacting solutions and for slowing the reaction where it is too rapid.
  • the process is particularly advantageous as it may operate over a wide range of pH values from 1 to 14, with the optimum pH values lying in the range between 10 and 11.5. As the pH approaches 1, the reaction rate slows.
  • the rate of flow of the pertechnetate containing solution may be controlled in order to provide an additional means of controlling the reaction rate.
  • process of the present invention may be easily incorporated into existing processes for the removal of radioactive species in aqueous media.
  • the process of the present invention achieves a highly regulated reduction of pertechnetate.
  • chromate can significantly effect the reduction of pertechnetate in a process according to the invention. Accordingly, when chromate is present in the aqueous medium to be treated, it is preferred to remove the chromate in an initial pre-treatment step, for example by the use of a reducing metal such as aluminium.
  • reaction vessel and, where present a pre-treatment column
  • reaction vessel in the form of a column containing aluminium as the reducing metal.
  • other form of reaction vessel could be used in either case, such as a simple stirred tank for a batch or continuous process, depending on the connections to the tank.
  • the rate of stirring may be controlled, both determining the local rate of contact of the medium with the metal.
  • Figure 1 shows a schematic apparatus used in column experiments performed to demonstrate the effectiveness of the present invention.
  • Figure 2 which shows a schematic diagram showing EARP plant modified to include the process of the present invention in use for the removal of technetium.
  • Figure 1 shows in schematic form experimental apparatus for carrying out the process of the present invention, the apparatus comprising pipes 3 and 5 connected respectively to the top and bottom of a column 1.
  • a pump 7 between the pipes is used to maintain the circulation of a pertechnetate containing solution around a closed system comprising the pipes 3, 5 and the column 1.
  • a tap 9 in pipe 3 is used to control circulation of the solution and a tap 11 in pipe 5 is used to remove samples of the solution.
  • the column 1 is packed with aluminium wool 13 and has a porous glass filter 15 at the bottom.
  • a pertechnetate solution is introduced and pumped continuously through the pipes 3, 5 and through the column 1 containing aluminium wool 13 for at least 24 hours. Movement of the pertechnetate through the column in contact with the aluminium results in a reduction of Tc v ⁇ to Tc v and/or Tc IV which plates out on the surface of the aluminium. Samples of the solution are removed through tap 11 at certain time intervals and analysed to measure the change in concentration of Tc v ⁇ in the solution.
  • reaction columns are only one exemplary form of reaction vessel.
  • an aqueous medium containing both pertechnetate and chromate as in the preceding paragraph was stirred in a simple tank containing aluminium powder (without pre-treatment of the medium). It was found an increase in the amount of aluminium powder in the tank led to a corresponding increase in the rate and degree of technetium removal.
  • the tank enables a larger amount of aluminium to be used in continuous contact with all of the aqueous medium, and so its use can be more effective than use of a column. It was found that by so increasing the amount of aluminium a similar performance could be obtained as by using a column with no chromate present.
  • the degree of technetium removal may alternatively or additionally be enhanced by increasing the contact or reaction time.
  • FIG. 2 shows a schematic apparatus 20 for carrying out the process of the present invention in use with the Enhanced Actinide Removal Plant indicated generally at 21.
  • An output pipe 22 of the EARP is connected to a column 1 which contains aluminium shot and which is connected to a pass/fail test compartment 24.
  • Selectable outputs from the test compartment comprise a recirculation pipe 28 which leads back to the top of the column 1 and an outflow pipe 26.
  • bulk effluent is passed through EARP and after filtration is tested for the level of contaminant present. If actinide content is below a prescribed acceptable level the effluent is passed out of the plant through pipe 22 into the column 1 containing aluminium particles where it reacts to give technetium (IV) and technetium (V). On leaving the column 1, the effluent is tested in the compartment 24 for the presence of technetium. If the effluent contains less than a prescribed level of technetium it is passed out through the outlet pipe 26, otherwise it is recirculated via pipe 28 back through the column for further removal of technetium-99.
  • the column may be replaced by disconnecting it from inlet pipe 22 and test compartment 24 when the aluminium shot is no longer effective.
  • further columns may be included in the apparatus and the circulation switched between columns 1 by known valve means once the aluminium in a column is exhausted.
  • an exhausted column is regenerated by washing with deionised water, regeneration with nitric acid (3 molar is preferred), and further washing with deionised water. This regeneration process may be repeated a plurality of times. Experimental trials have shown that regeneration can be repeated at least 5 times, with the column performance being essentially unaffected. However, there is a significant loss of aluminium during each regeneration step.
  • test compartment 24 is connected to the front end of EARP, thereby removing pertechnetate prior to ultrafiltration.
  • the column is attached to an element or elements for providing controllable heating and/or cooling so to controllably alter the temperature of the column and the reaction rate.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Inorganic Chemistry (AREA)
  • Plasma & Fusion (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

La présente invention concerne un procédé de traitement d'un milieu aqueux contenant du technetium sous forme de pertechnenate dissous. Ce procédé consiste à mettre le milieu en contact avec un métal pour ramener le techteniun dissous à au moins une espèce de technetium non métallique d'état d'oxydation inférieur. Comme métal, on utilise de préférence de l'aluminium sur lequel viennent se déposer les espèces inférieures réduites de technetiun VI et V, ce qui facilite l'élimination du technetium. Une fois épuisé, l'aluminium peut être régénéré par un traitement acide. Ce procédé peut être utilisé conjointement avec d'autres techniques connues permettant d'éliminer d'autres ingrédients présents dans des déchets radioactifs.
PCT/GB1999/002077 1998-07-09 1999-07-01 Procede de traitement de dechets renfermant du technetium Ceased WO2000003398A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU45267/99A AU4526799A (en) 1998-07-09 1999-07-01 Method for treating waste containing technetium

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9814785.3 1998-07-09
GB9814785A GB9814785D0 (en) 1998-07-09 1998-07-09 Waste treatment method

Publications (1)

Publication Number Publication Date
WO2000003398A1 true WO2000003398A1 (fr) 2000-01-20

Family

ID=10835147

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1999/002077 Ceased WO2000003398A1 (fr) 1998-07-09 1999-07-01 Procede de traitement de dechets renfermant du technetium

Country Status (3)

Country Link
AU (1) AU4526799A (fr)
GB (1) GB9814785D0 (fr)
WO (1) WO2000003398A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001065570A3 (fr) * 2000-03-01 2001-12-20 British Nuclear Fuels Plc Traitement des dechets
US9388478B1 (en) 2014-12-19 2016-07-12 Savannah River Nuclear Solutions, Llc Technetium recovery from high alkaline solution
RU2635202C2 (ru) * 2015-10-28 2017-11-09 Общество с ограниченной ответственностью "Александра-Плюс" Способ переработки металлов, содержащих прочнофиксированные поверхностные радиоактивные загрязнения

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2660789A1 (fr) * 1990-04-09 1991-10-11 Westinghouse Electric Corp Procede de decontamination de metaux radioactifs.
EP0535837A1 (fr) * 1991-10-02 1993-04-07 Westinghouse Electric Corporation Décontamination de métaux radioactifs
GB2299201A (en) * 1995-01-23 1996-09-25 Covofinish Co Inc Method for removal of technetium from radio-contaminated material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2660789A1 (fr) * 1990-04-09 1991-10-11 Westinghouse Electric Corp Procede de decontamination de metaux radioactifs.
EP0535837A1 (fr) * 1991-10-02 1993-04-07 Westinghouse Electric Corporation Décontamination de métaux radioactifs
GB2299201A (en) * 1995-01-23 1996-09-25 Covofinish Co Inc Method for removal of technetium from radio-contaminated material

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001065570A3 (fr) * 2000-03-01 2001-12-20 British Nuclear Fuels Plc Traitement des dechets
US9388478B1 (en) 2014-12-19 2016-07-12 Savannah River Nuclear Solutions, Llc Technetium recovery from high alkaline solution
RU2635202C2 (ru) * 2015-10-28 2017-11-09 Общество с ограниченной ответственностью "Александра-Плюс" Способ переработки металлов, содержащих прочнофиксированные поверхностные радиоактивные загрязнения

Also Published As

Publication number Publication date
AU4526799A (en) 2000-02-01
GB9814785D0 (en) 1998-09-09

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