GB2191329A - Decontamination of surfaces - Google Patents
Decontamination of surfaces Download PDFInfo
- Publication number
- GB2191329A GB2191329A GB08712012A GB8712012A GB2191329A GB 2191329 A GB2191329 A GB 2191329A GB 08712012 A GB08712012 A GB 08712012A GB 8712012 A GB8712012 A GB 8712012A GB 2191329 A GB2191329 A GB 2191329A
- Authority
- GB
- United Kingdom
- Prior art keywords
- technetium
- effluent
- radioactive species
- ion exchange
- remove
- 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.)
- Granted
Links
- 238000005202 decontamination Methods 0.000 title claims description 10
- 230000003588 decontaminative effect Effects 0.000 title claims description 8
- 229910052713 technetium Inorganic materials 0.000 claims abstract description 50
- GKLVYJBZJHMRIY-UHFFFAOYSA-N technetium atom Chemical compound [Tc] GKLVYJBZJHMRIY-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000000034 method Methods 0.000 claims abstract description 31
- 230000002285 radioactive effect Effects 0.000 claims abstract description 18
- 239000000463 material Substances 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 11
- 239000004411 aluminium Substances 0.000 claims abstract description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000005342 ion exchange Methods 0.000 claims abstract description 10
- 239000001117 sulphuric acid Substances 0.000 claims abstract description 10
- 235000011149 sulphuric acid Nutrition 0.000 claims abstract description 10
- 239000007800 oxidant agent Substances 0.000 claims abstract description 8
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 claims abstract description 7
- 239000002516 radical scavenger Substances 0.000 claims abstract description 7
- 229910052768 actinide Inorganic materials 0.000 claims abstract description 6
- 150000001255 actinides Chemical class 0.000 claims abstract description 6
- 239000008139 complexing agent Substances 0.000 claims abstract description 4
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 17
- 229910052770 Uranium Inorganic materials 0.000 claims description 15
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims description 15
- 229910052781 Neptunium Inorganic materials 0.000 claims description 12
- LFNLGNPSGWYGGD-UHFFFAOYSA-N neptunium atom Chemical compound [Np] LFNLGNPSGWYGGD-UHFFFAOYSA-N 0.000 claims description 12
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 10
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 5
- 235000011152 sodium sulphate Nutrition 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 abstract description 2
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 15
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
- 239000000243 solution Substances 0.000 description 9
- 239000003456 ion exchange resin Substances 0.000 description 7
- 229920003303 ion-exchange polymer Polymers 0.000 description 7
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 6
- 229910052723 transition metal Inorganic materials 0.000 description 5
- 150000003624 transition metals Chemical class 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 159000000013 aluminium salts Chemical class 0.000 description 4
- 229920001429 chelating resin Polymers 0.000 description 4
- 239000002526 disodium citrate Substances 0.000 description 4
- 235000019262 disodium citrate Nutrition 0.000 description 4
- CEYULKASIQJZGP-UHFFFAOYSA-L disodium;2-(carboxymethyl)-2-hydroxybutanedioate Chemical compound [Na+].[Na+].[O-]C(=O)CC(O)(C(=O)O)CC([O-])=O CEYULKASIQJZGP-UHFFFAOYSA-L 0.000 description 4
- 229910001385 heavy metal Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- GKLVYJBZJHMRIY-OUBTZVSYSA-N Technetium-99 Chemical compound [99Tc] GKLVYJBZJHMRIY-OUBTZVSYSA-N 0.000 description 3
- CVKJXWOUXWRRJT-UHFFFAOYSA-N technetium dioxide Chemical compound O=[Tc]=O CVKJXWOUXWRRJT-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000003352 sequestering agent Substances 0.000 description 2
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Chemical compound [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 208000016253 exhaustion Diseases 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000012958 reprocessing Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000012321 sodium triacetoxyborohydride Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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
- G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
- G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
- G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Food Science & Technology (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
- Treatment Of Water By Ion Exchange (AREA)
Abstract
A process of decontaminating a surface of a component contaminated with a radioactive species such as technetium trapped under an oxide layer present on an aluminium component comprises removing the oxide layer with sulphuric acid, and treating the exposed technetium with a complexing agent such as citrate in the presence of an oxidising agent. An oxide scavenger may be added to prevent reformation of the oxide layer. Actinides can be removed from the resulting effluent by use of a chelating ion exchange material, and technetium by oxidation and use of a basic ion exchange material.
Description
SPECIFICATION
Decontamination of surfaces
This invention relates to the decontamination of surfaces and particularly, but not exclusively, to the removal of technetium from surfaces of aluminium containing components.
Aluminium components used in nuclear plants, especially enrichment plants, become contaminated with, for example, uranium, neptunium and technetium99. The bulk of the uranium and neptunium present on the surface of a component can be removed using a wet chemical route incorporating a chelating agent.
In the case of technetium, it is highly desirable to remove not only technetium on the surface of the component but also technetium bound under a layer of aluminium oxide present on the surface of the component. The presence of the oxide layer renders the trapped technetium inaccessible to the chemicals used to remove uranium from the surfaces of components. With technetium a further problem is encountered which is not encountered with uranium, in that a slight build up of technetium in the decontamination liquor results in some of the technetium plating back onto the surface. Consequently, the route used to remove uranium from the surfaces of components cannot be used to efficiently remove technetium from those surfaces.
According to the present invention, there is provided a method of decontaminating a surface of a component contaminated with a radioactive species trapped under an oxide layer present on the surface, said method comprising chemically treating the surface to remove the layer so as to substantially expose the radioactive species, converting the exposed radioactive species into a soluble form in the presence of an oxidising agent so as to substantially prevent reduction of the soluble form of the radioactive species to an insoluble form and hence prevent redeposition of the radioactive species on the surface.
Preferabiy, an oxide scavenger is present to substantially prevent reformation of the oxide layer.
The component may comprise aluminium or the component may contain aluminium.
The radioactive species may comprise Technetium or a derivative thereof, for example an oxide of technetium.
The radioactive species may be converted into a soluble form by treating with a complexing agent such as a citrate.
The oxidising agent may be hydrogen peroxide, and the oxide scavenger may be sodium sulphate.
It is also preferred that the component is chemically treated to substantially remove the oxide layer with sulphuric acid, but other chemicals capable of removing the layer may be used, for example an alkaline solution containing sequestering agents such as citrate or phosphate.
The contaminant can be removed from the liquor either continuously or batchwise. For example, Technetium can be removed by percolating the liquor over a basic ion exchange resin. Similarly copper and other transition metals are removed by circulation of the liquor over a chelating resin. This prevents transition metals, present in most aluminium alloys, from building up and destroying the hydrogen peroxide.
It is believed that the problem of technetium plating back onto the surface being decontaminated is due to the reduction of a soluble pertechnate species (TcO4-) to an insoluble technetium species, such as technetium dioxide (TcO2). When the component contains aluminium the reduction may be carried out by the aluminium itself.
It is thought that the technetium species eg TCO2 on the surface of the component is converted into the soluble form by for example formation of a citrate complex and that the technetium in this complex is oxidised by the oxidising agent to a species such as pertechnate (TCO4-). The citrate may not be bound to the technetium in the oxidised species (TCO4-).
This oxidation prevents redeposition of technetium by virtue of an equilibrium between insoluble technectium such as TCO2 and the soluble technetium complex and also prevents redeposition due to reduction of the oxidised technetium species back to an insoluble form such as TcO2.
Since radioactive species trapped under an oxide layer are removed, the invention may be used to increase the decontamination efficiency of species whose bulk can be removed from surfaces by routes which do not remove trapped species. For example neptunium present on surfaces, but not that under an oxide layer, can be removed by conventional routes and the trapped neptunium can be removed by the method of this invention.
The present invention further provides a method of treating effluent containing actinides and technetium, said method comprising contacting the effluent with a chelating ion exchange material to substantially remove the actinides, and contacting the effluent with a basic ion exchange material to substantially remove the technetium.
Preferably, the technetium is in an oxidised form. The effluent may contain uranium, neptunium and technetium.
The effluent may comprise an acid such as sulphuric acid. It is preferable that the pH of the effluent is adjusted to pH 0.5 to 3 before the effluent is contacted with the basic ion exchange material.
The present invention also provides a method of treating the effluents resulting from the removal of uranium and technetium from components containing aluminium. Such method will become apparent from the ensuing description of a preferred embodiment.
The process is essentially a two bath system. In the first bath the surface is conditioned by removal of the aluminium oxide layer so as to expose the technetium contaminant.
The second bath contains an oxidant, an oxide scavenger and a complexant to remove the exposed technetium.
To promote further understanding of the invention an embodiment will now be described by way of example only.
Contaminated components may be treated initially with a citric acid solution to remove uranium and neptunium present on the surfaces of the components. The components are then transferred to a wash water tank, which is held at a temperature of 50-70"C, to prevent carry over of chemicals, uranium and neptunium. After this washing stage the components are placed in a tank containing a 1M to 3M solution of sulphuric acid held at 50"C to 70"C to remove the aluminium oxide and therefore expose the technetium.Alternatively a 0.1M alkaline solution containing sequestering agents such as citrate or phosphate can be used to remove the aluminium oxide layer
From this tank the components are firstly transferred to a wash water tank at ambient temperature and then to a bath containing a mixture of disodium citrate (0.05M to 0.2M), an oxidant, hydrogen peroxide (5 volumes to 20 volumes), and an oxide scavenger, sodium sulphate (0.05M to 0.2M), held at ambient temperature.
It is preferable to provide that the contaminated components are subjected to a second series of tanks identical to those described above except for the omission of a second citric acid tank. This further cleaning process is desirable to give a higher decontamination efficiency.
The liquor present in the bath containing disodium citrate, hydrogen peroxide and sodium sulphate is continually circulated over a chelating resin, such as AMBERLITE (RTM) IRC 718, to remove copper and other transition metals, and over a basic ion exchange resin, such as
AMBERLITE (RTM) IRA 94S or IRA 402, to remove technetium. All these resins are manufactured by the Rohm and Haas Company. It is desirable to remove these transition metals since a build up would destroy the hydrogen peroxide. Alternatively, the use of a peroxide stabilizer in the solution such as "STAB
TABS" supplied by Interox Ltd can achieve the same result. Removal of technetium leads to a higher decontamination efficiency.
The effluent resulting from the decontamination process described above consists of four types:
a. Citric acid (0.33M) containing heavy metals, technetium, uranium and aluminium salts.
b. Sulphuric acid (2M) containing aluminium salts, technetium and traces of heavy metals, uranium and neptunium.
c. Disodium citrate (0.1M), hydrogen peroxide (10 volumes), sodium sulphate solution (0. 1 M) containing technetium, aluminium and traces of heavy metals.
d. Wash water containing traces of technetium.
These effluents can be treated in the following ways. The citric acid effluent is acidified to a pH in the range 0 to 1 by using sulphuric acid. Sodium persulphate is added to produce about a 1% solution. The liquor is then heated to 60"C-90"C and held at this temperature for 20 minutes to allow the technetium to oxidise.
Depending on the temperature employed, a further period of up to 24 hours is required to destroy residual persulphate. The liquor is then cooled, and its pH adjusted to greater than 13 to precipitate uranium and neptunium as diuranate and dineptunate which is then removed using standard centrifuge methods. Finally the liquor is percolated over a basic ion exchange resin such as the said IRA 94S or IRA 402 to remove technetium99. An alternative effluent processing scheme for the citric acid bath is to evaporate off the excess water in order to recover an active solid waste material.
Residual traces of uranium and neptunium may be removed from the sulphuric acid by percolating the untreated solution over a suitable chelating ion exchange resin such as duolite ES 467 supplied by Rohn and Haas Ltd.
Sodium persulphate is then added to the sulphuric acid effluent to produce about a 1% solution. The temperature of the liquor is then raised to 60-90"C and held at this temperature for 20 minutes. Up to 24 hours are needed to complete the destruction of excess persulphate. The cooled liquor may be treated without pH adjustment or is adjusted to pH 0.5 to 3 by addition of caustic liquor, solidus are removed by filtration and then the liquor is percolated over a basic ion exchange resin, to remove technetium. Improved ion exchange utilisation is achieved at the higher pH. The resulting liquor is free of technetium99 and can be safely released into the environment.
If the concentration of aluminium salts are high premature precipitation in the process liquor may occur. In order to prevent this, aluminium salts can be removed continually from solution by circulating the liquor through an acid purification unit such as an Eco-Tek (TM) unit marketted by Eco-Tec Ltd of Canada. The acidic liquor is then returned to the processing tank and upon final exhaustion is treated as described in the previous paragraph.
The disodium citrate solution is maintained low in technetium and transition metals by the use of on-line ion exchange resins during the decontamination process. Before disposal it is desirable to remove the hydrogen peroxide present in the effluent. This is achieved by percolating the liquor over activated charcoal at ambient temperature. Following this stage the liquor may be percolated over a basic ion exchange resin to remove any remaining traces of technetium before it is discharged into the environment.
Finally the wash water is usually so low in technetium, uranium, neptunium and heavy metals that it requires no further treatment.
Although the invention has been described in the context of removal of technetium from aluminium components, the invention may also be employed to decontaminate components made from other materials, such as mild steel and nickel, ie materials which may be used in other nuclear plants such as reprocessing plants.
Claims (17)
1. A method of decontaminating a surface of a component contaminated with a radioactive species trapped under an oxide layer present on the surface, said method comprising chemically treating the surface to remove the layer so as to substantially expose the radioactive species, converting the exposed radio active species into a soluble form in the presence of an oxidising agent so as to substantially prevent reduction of the soluble form of the radioactive species to an insoluble form and hence prevent redeposition of the radioactive species on the surface.
2. A method as claimed in claim 1 in which an oxide scavenger is present.
3. A method as claimed in claim 1 or 2 in which the component contains aluminium.
4. A method as claimed in any one of
Claims 1, 2 or 3 in which the radioactive species comprises technetium.
5. A method as claimed in any one of claims 1 to 4 in which the radioactive species is converted into the soluble form by treatment with a complexing agent.
6. A method as claimed in claim 5 in which the complexing agent comprises citrate.
7. A method as claimed in any one of claims 2 to 6 in which the oxide scavenger comprises sodium sulphate.
8. A method as claimed in any one of claims 1 to 7 in which the surface is treated with sulphuric acid to remove the layer.
9. A method as claimed in any one of claims 1 to 9 in which the oxidising agent comprises hydrogen peroxide.
10. A method as claimed in any one of claims 1 to 9 in which the radioactive species is removed from the decontaminating liquor during the decontamination.
11. A method of treating effluent containing actinides and technetium, said method comprising contacting the effluent with a chelating ion exchange material to substantially remove the actinides, and contacting the effluent with a basic ion exchange material to substantially remove the technetium.
12. A method as claimed in claim 11 in which the technetium is oxidised to facilitate removal by the basic ion exchange material.
13. A method as claimed in claim 11 or 12 in which the effluent comprises uranium, neptunium and technetium.
14. A method as claimed in any one of claims 11, 12 or 13 in which the effluent comprises sulphuric acid.
15. A method as claimed in any one of claims 11 to 14 in which the pH of the effluent is adjusted to pH 0.5 to 3 before removal of the technetium by the basic ion exchange material.
16. A method of decontaminating a surface of a component with a radioactive species trapped under an oxide layer substantially as hereinbefore described.
17. A method of treating effluent containing actinides and technetium substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8712012A GB2191329B (en) | 1986-06-04 | 1987-05-21 | Decontamination of surfaces |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868613522A GB8613522D0 (en) | 1986-06-04 | 1986-06-04 | Technetium decontamination |
| GB8712012A GB2191329B (en) | 1986-06-04 | 1987-05-21 | Decontamination of surfaces |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8712012D0 GB8712012D0 (en) | 1987-07-22 |
| GB2191329A true GB2191329A (en) | 1987-12-09 |
| GB2191329B GB2191329B (en) | 1989-12-13 |
Family
ID=26290854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8712012A Expired GB2191329B (en) | 1986-06-04 | 1987-05-21 | Decontamination of surfaces |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2191329B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2648946A1 (en) * | 1989-06-27 | 1990-12-28 | Electricite De France | METHOD OF DISSOLVING OXIDE DEPOSITED ON METALLIC SUBSTRATE AND ITS APPLICATION TO DECONTAMINATION |
| EP0548538A1 (en) * | 1991-12-20 | 1993-06-30 | Westinghouse Electric Corporation | Transition metal decontamination process |
| EP0550221A1 (en) * | 1992-01-03 | 1993-07-07 | BRADTEC Limited | Composition and process for decontamination of radioactive materials |
-
1987
- 1987-05-21 GB GB8712012A patent/GB2191329B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2648946A1 (en) * | 1989-06-27 | 1990-12-28 | Electricite De France | METHOD OF DISSOLVING OXIDE DEPOSITED ON METALLIC SUBSTRATE AND ITS APPLICATION TO DECONTAMINATION |
| EP0406098A1 (en) * | 1989-06-27 | 1991-01-02 | Electricite De France | Process for dissolving oxyde deposited on a metallic substrate and its application to decontamination |
| EP0548538A1 (en) * | 1991-12-20 | 1993-06-30 | Westinghouse Electric Corporation | Transition metal decontamination process |
| EP0550221A1 (en) * | 1992-01-03 | 1993-07-07 | BRADTEC Limited | Composition and process for decontamination of radioactive materials |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8712012D0 (en) | 1987-07-22 |
| GB2191329B (en) | 1989-12-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20020521 |