WO1998022953A1 - Reducing radionuclide surface contamination of a metallic component - Google Patents

Reducing radionuclide surface contamination of a metallic component Download PDF

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Publication number
WO1998022953A1
WO1998022953A1 PCT/GB1997/003134 GB9703134W WO9822953A1 WO 1998022953 A1 WO1998022953 A1 WO 1998022953A1 GB 9703134 W GB9703134 W GB 9703134W WO 9822953 A1 WO9822953 A1 WO 9822953A1
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WO
WIPO (PCT)
Prior art keywords
metallic component
surface contamination
radionuclide
component
reducing
Prior art date
Application number
PCT/GB1997/003134
Other languages
French (fr)
Inventor
Alfred Richard Solly
Duncan Philp
Original Assignee
Babcock Rosyth Defence Limited
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 Babcock Rosyth Defence Limited filed Critical Babcock Rosyth Defence Limited
Priority to AU49586/97A priority Critical patent/AU4958697A/en
Publication of WO1998022953A1 publication Critical patent/WO1998022953A1/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
    • G21F9/001—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
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating

Definitions

  • This invention relates to a method of, and apparatus for, reducing radionuclide surface contamination of a metallic component and, more particularly, to reducing to an acceptable level the amount of radio-active contaminants adhering to surfaces of components of a nuclear plant upon decommissioning.
  • a method of reducing radionuclide surface contamination of a metallic component including subjecting a contaminated surface layer of the component to a concentrated spray of electrolytic liquid flowing in a closed flow circuit, the electrolytic liquid having a composition reactive with metallic oxides present in the contaminated surface layer, applying an electrical current to the concentrated spray to be conducted through the concentrated spray of electrolytic liquid to the metallic component acting as an anode, removing the metallic oxides from the contaminated surface layer as reaction products in the electrolytic liquid, removing radionuclide particles dislodged or detached from the contaminated surface layer in suspension in the electrolytic liquid, passing the electrolytic liquid through recovery means arranged to remove radionuclide particles from suspension and re-utilising the electrolytic liquid in the concentrated spray in the closed flow circuit.
  • apparatus including pump means arranged to urge a stream of electrolytic liquid around a closed flow circuit, the closed flow circuit including a concentrated spray nozzle connected as a cathode to a source of direct current electric power, means to traverse the concentrated spray nozzle in close proximity to a radionuclide contaminated surface of a component electrically connected as an anode and reservoir means for collection of the electrolytic liquid following discharge from the concentrated spray nozzle and impingement on the contaminated surface, the reservoir means being connected to an inlet of the pump means .
  • the decontamination equipment 2 includes a closed flow circuit 6 comprising a pump 8, a settling tank 10, a fine filter 12, a delivery conduit 14, a concentrated spray nozzle 16, a reservoir 18 for electrolytic treatment liquid 20 and an uptake conduit 22 connected to the pump 8.
  • the reservoir 18 is formed in a base portion 24 of the spherical metal vessel 4.
  • a tank or vessel is provided to serve as an external reservoir.
  • the concentrated spray nozzle 16 is mounted on an articulated positioning arm 26 manoeuvrable to traverse the concentrated spray nozzle 16 across the complete interior wall surface 28 of the spherical metal vessel 4, closely adjacent to the surface 28.
  • the positioning arm 26 is remotely controlled either through a manually operated mechanical linkage or through a motorised system as a robotic arrangement. Adjacent the concentrated spray nozzle 16, the positioning arm 26 carries a closed circuit television camera and a geiger counter sensor (not shown) to facilitate visual and radioactivity monitoring within the spherical metal vessel 4.
  • the concentrated spray nozzle 16 and associated monitoring equipment is mounted on a pig, for moving through pipework, or is mounted on a moveable robot device, or is fixed whilst the component for decontamination is manipulated to move relative thereto, where conditions permit and are suitable an array of concentrated spray nozzles may be utilised to produce an extended spray pattern.
  • the electrolytic treatment liquid 20 is selected to be reactive with a metallic oxide surface layer formed on the wall surface 28 during the service life of the component.
  • a typical surface layer may contain oxides of iron, nickel, chromium, manganese and the like.
  • the electrolytic treatment liquid is selected from liquid compositions giving an enhanced electrolytic effect. Whilst a 5% nitric acid solution is favoured, other strengths or other acids, such as oxalic acid or phosphoric acid, or caustic alkali solutions, such as sodium hydroxide solution, may be utilised.
  • the concentrated spray nozzle 16 is provided with an electrically insulated mounting on the positioning arm 26 and is connected through a lead 30 to a source 32 of direct current electrical power to serve as a cathode.
  • the electrical power supplied to the concentrated spray nozzle serving as a cathode is in the range of between 1 and 150 amps per tenth of a square metre.
  • the electrical current is conducted through the concentrated spray to the spherical metal vessel 4, which, in turn, is connected to a positive earth terminal 34 to serve as an anode.
  • a metallic component such as the spherical metal vessel 4 from decommissioned nuclear plant and requiring to be treated to reduce the radioactivity emanating from radionuclides deposited in the metallic oxide surface layer formed on the component during service in the nuclear plant is positioned in a decommissioning zone and in a manner permitting access of the concentrated spray nozzle to the complete contaminated surfaces.
  • the spherical metal vessel 4 is located relative to the positioning arm 16.
  • the base portion 24 of the vessel 4 is sealed to provide the reservoir 18 of relatively shallow depth so as not to impede the action of the concentrated spray upon the base portion 24.
  • the spherical metal vessel 4 is connected to the positive earth terminal 34.
  • Electrolytic treatment liquid 20 is then supplied from a supply tank (not shown) to the pump 8, which is energised, and the electrolytic treatment liquid 20 pumped around the flow circuit 6 to discharge at the concentrated spray nozzle 16 closely adjacent the interior wall surface 28. Electrolytic treatment liquid 20 collecting in the reservoir 18 is returned to the pump 8 through the uptake conduit 22.
  • the electrolytic treatment liquid reacts with the metallic oxides in the contaminated surface layer to dissolve the metallic oxides and thereby tends to dislodge or detach any radionuclide particles, such as particles of cobalt 60, attached to the surface 28, which then become suspended and entrained in the electrolytic treatment liquid.
  • the reactions and the dislodgement or detachment of the radionuclides are enhanced by the electrolytic action arising on the application of the electric current to the concentrated spray nozzle 16 serving as a cathode.
  • the electrolytic treatment liquid 20 passes through the settling tank 10 and fine filter 12 where the radionuclides settle out or are filtered out.
  • alternative means may be utilised to remove the radionuclides from the electrolytic treatment liquid 20.
  • Such means may include distillation, centrifuges or chemical means.
  • the chemical means may also serve to effect removal of radioactive nuclides dissolved in the treatment liquid 20.
  • the geiger counter sensor mounted on the positioning arm 26 is utilised to monitor the level of residual radioactivity and, if necessary, treatment of specific areas, such as welds, repeated, until the complete component has been reduced to an acceptable level of radioactivity.
  • the reservoir 18 and the flow circuit are drained and washed down. Particles arrested in the settling tank 10 and fine filter 12, which largely will be radionuclides are removed, together with, if necessary, the settling tank 10 and fine filter 12, for disposal in an appropriate manner.
  • a component has, or may be positioned with, upright side walls, such as a cylindrical vessel 36 as shown in Figure 2, an inflatable raft 38 is positioned to float on a body of water 40 in the vessel 36 and arranged to make close contact with the side wall 42 of the vessel.
  • a return pump 44 is positioned on the raft 38.
  • a moveable, concentrated spray, nozzle and cathode assembly 46 is positioned to direct a concentrated spray of electrolytic decontamination treatment liquid on to a circumferential band of the side wall 42 at a level above the raft 38.
  • the treatment liquid collects on the raft 38 and is returned by the pump 44 through a flexible line 50 to a reservoir 48 positioned above the vessel 36 for re-use, being supplied, if necessary through a filter and pump (not shown), to the nozzle and cathode assembly 46 through a flexible connection 52.
  • the cylindrical vessel 36 is filled to an intermediate level with water 40, which serves to provide a radiation shield.
  • the raft 38 is positioned on the surface of the water 40 and inflated to form a close contact sliding seal with the wall 42.
  • a selected electrolytic treatment liquid 20 is supplied to the reservoir 48 and discharged as a concentrated spray charged as a cathode through the nozzle assembly 46. Since the raft 38 makes a close contact seal with the wall 42, the treatment liquid collects on the raft 38 and is returned through the pump and the line 50 to the reservoir 48.
  • Treatment is commenced at the top of the vessel 36, and, as respective, successive, circumferential bands of the wall 42 are decontaminated, the volume of the body of water 40 is reduced by draining the water from the vessel to lower the raft 38.
  • the axial position of the nozzle 46 is successively lowered to subject successive lower circumferential bands of the wall 42 to treatment.
  • the raft 38 is deflated and removed. Where it is necessary to treat the base of the vessel 36, the procedure described in conjunction with Figure 1 is utilised.
  • a radiation shield is provided, thereby reducing the exposure to radiation of operatives during the initial stages as compared to an arrangement in which the body of water is not present, whilst utilisation of the raft 38 avoids dilution of the treatment liquid by mixing with the water 40 and avoids the need to effect continuous decontamination of the water 40.

Abstract

Apparatus for reducing radionuclide contamination of a metallic component includes a concentrated spray nozzle (16) mounted on an articulated positioning arm (26) arranged to traverse completely a surface (28) of a component of a nuclear plant upon de-commissioning and subject to radio-active contamination. The nozzle (16) is connected, as a cathode, to an electrical power source (32) to give an electrical current density of approximately 50 amps per tenth square metre with the component connected as an anode. An electrolytic treatment liquid (20), such as 5 % nitric acid solution, is discharged through the nozzle (16) to react with at least any metallic oxide surface layer to dislodge or detach any radionuclide particles, such as particles of cobalt 60, attached to the surface (28). The electrolytic treatment liquid (20) drains to a shallow reservoir formed by the component or to a separate reservoir (18) and is then passed to a settling tank (10) and fine filter (20) where the radionuclides settle out or are filtered out and the liquid re-cycled. Where the component has upright side walls, an inflatable raft may be utilised to form a reservoir above the raft floating on a body of shielding water in the component.

Description

Reducing radionuclide surface contamination of a metallic component
Description
This invention relates to a method of, and apparatus for, reducing radionuclide surface contamination of a metallic component and, more particularly, to reducing to an acceptable level the amount of radio-active contaminants adhering to surfaces of components of a nuclear plant upon decommissioning.
Safe disposal as steel debris of components contaminated with radionuclides, such as components from decommissioned nuclear power plant, is difficult. Present disposal techniques are labour and dose intensive and incur high transport and storage costs. Hitherto, component decontamination has been achieved utilising electro-polishing or acid pickling techniques involving immersing the component in a bath of electrolyte or acid. However, although the component may be decontaminated to an acceptable level of radioactivity, a relatively large volume of liquid is required, which, in turn, presents difficulties for safe disposal.
According to one aspect of the present invention, there is provided a method of reducing radionuclide surface contamination of a metallic component including subjecting a contaminated surface layer of the component to a concentrated spray of electrolytic liquid flowing in a closed flow circuit, the electrolytic liquid having a composition reactive with metallic oxides present in the contaminated surface layer, applying an electrical current to the concentrated spray to be conducted through the concentrated spray of electrolytic liquid to the metallic component acting as an anode, removing the metallic oxides from the contaminated surface layer as reaction products in the electrolytic liquid, removing radionuclide particles dislodged or detached from the contaminated surface layer in suspension in the electrolytic liquid, passing the electrolytic liquid through recovery means arranged to remove radionuclide particles from suspension and re-utilising the electrolytic liquid in the concentrated spray in the closed flow circuit.
In another aspect of the invention, there is provided apparatus including pump means arranged to urge a stream of electrolytic liquid around a closed flow circuit, the closed flow circuit including a concentrated spray nozzle connected as a cathode to a source of direct current electric power, means to traverse the concentrated spray nozzle in close proximity to a radionuclide contaminated surface of a component electrically connected as an anode and reservoir means for collection of the electrolytic liquid following discharge from the concentrated spray nozzle and impingement on the contaminated surface, the reservoir means being connected to an inlet of the pump means .
The invention will now be described, by way of example, with reference to the accompanying, diagrammatic drawings showing, in Figure 1, decontamination equipment 2 positioned to treat a spherical metal vessel 4 and, in Figure 2, positioned to treat a cylindrical metal vessel 36.
The decontamination equipment 2 includes a closed flow circuit 6 comprising a pump 8, a settling tank 10, a fine filter 12, a delivery conduit 14, a concentrated spray nozzle 16, a reservoir 18 for electrolytic treatment liquid 20 and an uptake conduit 22 connected to the pump 8. The reservoir 18 is formed in a base portion 24 of the spherical metal vessel 4. In other arrangements (not shown) in which the component for decontamination does not have a configuration suitable for the formation of an integral reservoir 18, a tank or vessel is provided to serve as an external reservoir.
As shown, the concentrated spray nozzle 16 is mounted on an articulated positioning arm 26 manoeuvrable to traverse the concentrated spray nozzle 16 across the complete interior wall surface 28 of the spherical metal vessel 4, closely adjacent to the surface 28. The positioning arm 26 is remotely controlled either through a manually operated mechanical linkage or through a motorised system as a robotic arrangement. Adjacent the concentrated spray nozzle 16, the positioning arm 26 carries a closed circuit television camera and a geiger counter sensor (not shown) to facilitate visual and radioactivity monitoring within the spherical metal vessel 4.
In other arrangements (not shown) the concentrated spray nozzle 16 and associated monitoring equipment is mounted on a pig, for moving through pipework, or is mounted on a moveable robot device, or is fixed whilst the component for decontamination is manipulated to move relative thereto, where conditions permit and are suitable an array of concentrated spray nozzles may be utilised to produce an extended spray pattern.
The electrolytic treatment liquid 20 is selected to be reactive with a metallic oxide surface layer formed on the wall surface 28 during the service life of the component. A typical surface layer may contain oxides of iron, nickel, chromium, manganese and the like. In addition, the electrolytic treatment liquid is selected from liquid compositions giving an enhanced electrolytic effect. Whilst a 5% nitric acid solution is favoured, other strengths or other acids, such as oxalic acid or phosphoric acid, or caustic alkali solutions, such as sodium hydroxide solution, may be utilised.
The concentrated spray nozzle 16 is provided with an electrically insulated mounting on the positioning arm 26 and is connected through a lead 30 to a source 32 of direct current electrical power to serve as a cathode. The electrical power supplied to the concentrated spray nozzle serving as a cathode is in the range of between 1 and 150 amps per tenth of a square metre. The electrical current is conducted through the concentrated spray to the spherical metal vessel 4, which, in turn, is connected to a positive earth terminal 34 to serve as an anode.
In operation, a metallic component, such as the spherical metal vessel 4, from decommissioned nuclear plant and requiring to be treated to reduce the radioactivity emanating from radionuclides deposited in the metallic oxide surface layer formed on the component during service in the nuclear plant is positioned in a decommissioning zone and in a manner permitting access of the concentrated spray nozzle to the complete contaminated surfaces. Thus, as shown, the spherical metal vessel 4 is located relative to the positioning arm 16. The base portion 24 of the vessel 4 is sealed to provide the reservoir 18 of relatively shallow depth so as not to impede the action of the concentrated spray upon the base portion 24. The spherical metal vessel 4 is connected to the positive earth terminal 34. Electrolytic treatment liquid 20 is then supplied from a supply tank (not shown) to the pump 8, which is energised, and the electrolytic treatment liquid 20 pumped around the flow circuit 6 to discharge at the concentrated spray nozzle 16 closely adjacent the interior wall surface 28. Electrolytic treatment liquid 20 collecting in the reservoir 18 is returned to the pump 8 through the uptake conduit 22. The electrolytic treatment liquid reacts with the metallic oxides in the contaminated surface layer to dissolve the metallic oxides and thereby tends to dislodge or detach any radionuclide particles, such as particles of cobalt 60, attached to the surface 28, which then become suspended and entrained in the electrolytic treatment liquid. The reactions and the dislodgement or detachment of the radionuclides are enhanced by the electrolytic action arising on the application of the electric current to the concentrated spray nozzle 16 serving as a cathode. In the flow circuit 6, the electrolytic treatment liquid 20 passes through the settling tank 10 and fine filter 12 where the radionuclides settle out or are filtered out. In alternative arrangements, not shown, alternative means may be utilised to remove the radionuclides from the electrolytic treatment liquid 20. Such means may include distillation, centrifuges or chemical means. The chemical means may also serve to effect removal of radioactive nuclides dissolved in the treatment liquid 20.
Following contacting the complete interior wall surface 28 with the electrolytic treatment liquid, the geiger counter sensor mounted on the positioning arm 26 is utilised to monitor the level of residual radioactivity and, if necessary, treatment of specific areas, such as welds, repeated, until the complete component has been reduced to an acceptable level of radioactivity. At this juncture, or even preparatory to checking the level of residual radio-activity, the reservoir 18 and the flow circuit are drained and washed down. Particles arrested in the settling tank 10 and fine filter 12, which largely will be radionuclides are removed, together with, if necessary, the settling tank 10 and fine filter 12, for disposal in an appropriate manner.
It will be appreciated that the above described treatment method may be utilised with a component in situ where provision may be made for contacting the required surfaces with the concentrated spray of electrolytic treatment liquid, which is then readily recoverable subsequent to contacting the component and for making the requisite electrical connections.
hen a component has, or may be positioned with, upright side walls, such as a cylindrical vessel 36 as shown in Figure 2, an inflatable raft 38 is positioned to float on a body of water 40 in the vessel 36 and arranged to make close contact with the side wall 42 of the vessel. A return pump 44 is positioned on the raft 38. A moveable, concentrated spray, nozzle and cathode assembly 46 is positioned to direct a concentrated spray of electrolytic decontamination treatment liquid on to a circumferential band of the side wall 42 at a level above the raft 38. The treatment liquid collects on the raft 38 and is returned by the pump 44 through a flexible line 50 to a reservoir 48 positioned above the vessel 36 for re-use, being supplied, if necessary through a filter and pump (not shown), to the nozzle and cathode assembly 46 through a flexible connection 52.
In operation, the cylindrical vessel 36 is filled to an intermediate level with water 40, which serves to provide a radiation shield. The raft 38 is positioned on the surface of the water 40 and inflated to form a close contact sliding seal with the wall 42. As described in conjunction with Figure 1, with the electric circuit energised, a selected electrolytic treatment liquid 20 is supplied to the reservoir 48 and discharged as a concentrated spray charged as a cathode through the nozzle assembly 46. Since the raft 38 makes a close contact seal with the wall 42, the treatment liquid collects on the raft 38 and is returned through the pump and the line 50 to the reservoir 48. Treatment is commenced at the top of the vessel 36, and, as respective, successive, circumferential bands of the wall 42 are decontaminated, the volume of the body of water 40 is reduced by draining the water from the vessel to lower the raft 38. The axial position of the nozzle 46 is successively lowered to subject successive lower circumferential bands of the wall 42 to treatment. Upon approaching the base of the vessel 36, the raft 38 is deflated and removed. Where it is necessary to treat the base of the vessel 36, the procedure described in conjunction with Figure 1 is utilised.
By utilising the body of water 40 in the vessel initially, a radiation shield is provided, thereby reducing the exposure to radiation of operatives during the initial stages as compared to an arrangement in which the body of water is not present, whilst utilisation of the raft 38 avoids dilution of the treatment liquid by mixing with the water 40 and avoids the need to effect continuous decontamination of the water 40.

Claims

Claims
1. A method of reducing radio-nuclide surface contamination of a metallic component including subjecting a contaminated surface layer of the component to a concentrated spray of electrolytic liquid flowing in a closed flow circuit, the electrolytic liquid having a composition reactive with metallic oxides present in the contaminated surface layer, applying an electrical current to the concentrated spray to be conducted through the concentrated spray to the metallic component acting as an anode, removing the metallic oxides from the contaminated surface layer as reaction products in the electrolytic liquid, removing radionuclide particles dislodged or detached from the contaminated surface layer in suspension the electrolytic liquid, passing the electrolytic liquid through recovery means arranged to remove radionuclide particles from suspension and re-utilising the electrolytic liquid in the concentrated spray in the closed flow circuit.
2. A method of reducing radionuclide surface contamination of a metallic component as claimed in
Claim 1, wherein the electrolytic liquid has an acidic composition.
3. A method of reducing radionuclide surface contamination of a metallic component as claimed in
Claim 2, wherein the electrolytic liquid is dilute nitric acid.
4. A method of reducing radionuclide surface contamination of a metallic component as claimed in
Claim 3, wherein the electrolytic liquid is a 5% solution of nitric acid.
5. A method of reducing radionuclide surface contamination of a metallic component as claimed in any preceding Claim, wherein the concentrated spray is connected, as a cathode, to a source of electrical power with the component connected as an anode and an electrical current of a density of between 1 and 150 amps per tenth square metre is applied through the concentrated spray.
6. A method of reducing radionuclide surface contamination of a metallic component as claimed in Claim 5, wherein an electrical current density of approximately 50 amps per tenth square metre is applied through the concentrated spray.
7. A method of reducing radionuclide surface contamination of a metallic component as claimed in any preceding Claim, wherein the suspended radionuclide particles are removed from the flowing electrolytic liquid by passing the electrolytic liquid through mechanical separating means.
8. A method of reducing radionuclide surface contamination of a metallic component as claimed in Claim 7, wherein the radionuclide particles are permitted to settle out of suspension in a settling tank.
9. A method of reducing radionuclide surface contamination of a metallic component as claimed in
Claim 8, wherein radionuclide particles remaining in suspension downstream of the settling tank are removed from the electrolytic liquid by passage through a fine filter.
10. A method of reducing radionuclide surface contamination of a metallic component as claimed in any preceding Claim, wherein the metallic component is arranged to form a reservoir for the collection of the electrolytic liquid as a part of the closed flow circuit.
11. Apparatus for reducing radionuclide surface contamination of a metallic component including a pump means arranged to urge a stream of electrolytic liquid around a closed flow circuit, the closed flow circuit including a concentrated spray nozzle connected as a cathode to a source of direct current electrical power, means to traverse the concentrated spray nozzle in close proximity to a radionuclide contaminated surface of a component connected as an anode and reservoir means for collection of the electrolytic liquid following discharge from the concentrated spray nozzle and impingement on the contaminated surface, the reservoir means being connected to an inlet of the pump means.
12. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in Claim 11, wherein the closed flow circuit includes mechanical separating means adapted to separate particles suspended in the flowing electrolytic liquid from the electrolytic liquid.
13. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in Claim 12, wherein the mechanical separating means includes a settling tank.
14. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in Claim 12 or Claim 13, wherein the mechanical separating means includes a fine filter.
15. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 14, wherein the electrolytic liquid is acidic.
16. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in
Claim 15, wherein the electrolytic liquid is dilute nitric acid.
17. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in
Claim 16, wherein the electrolytic liquid is a 5% solution of nitric acid.
18. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 17, wherein the concentrated spray nozzle is connected to a source of electrical power arranged to deliver an electrical current density in the range of 1 to 150 amps per tenth square metre.
19. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in Claim 18, wherein the source of electrical power is arranged to deliver an electrical power density of approximately 50 amps per tenth square metre.
20. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 19, wherein the metallic component is arranged to form the reservoir means.
21. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 10, wherein the concentrated spay nozzle is mounted on a positioning arm operable to traverse the concentrated spray nozzle in close proximity to the surface.
22. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 21, wherein the concentrated spray nozzle is mounted on a robotic device enabling the metallic component to be treated in a location as occupied by the metallic component when in service as a part of a nuclear plant.
23. Apparatus for reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 11 to 21, wherein the metallic component has upright side walls and a closed base and a raft means is arranged to be floated on a body of water within the side walls and base in close sealing contact with the side walls to form the reservoir means above the raft means.
24. A method of reducing radionuclide surface contamination of a metallic component as claimed in any one of Claims 1 to 10, wherein the metallic component has upright side walls and a closed base and an inflatable raft means is introduced into an upper region of the component and is inflated to float on a body of water within the side walls and base in close sealing contact with the side walls to form on an upper face of the inflatable raft the reservoir for the collection of the electrolytic liquid as a part of the closed flow circuit and the level of the inflatable raft is varied by varying the volume of the body of water within the component.
PCT/GB1997/003134 1996-11-15 1997-11-14 Reducing radionuclide surface contamination of a metallic component WO1998022953A1 (en)

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Application Number Priority Date Filing Date Title
AU49586/97A AU4958697A (en) 1996-11-15 1997-11-14 Reducing radionuclide surface contamination of a metallic component

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9623953.8 1996-11-15
GB9623953A GB2319259A (en) 1996-11-15 1996-11-15 reducing radionucleide contamination of a metallic component

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6264336B1 (en) 1999-10-22 2001-07-24 3M Innovative Properties Company Display apparatus with corrosion-resistant light directing film
US6626545B2 (en) 1999-10-22 2003-09-30 3M Innovative Properties Co Light directing construction having corrosion resistant feature

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2819622B1 (en) * 2001-01-17 2004-04-02 Maintenance Nucleaire Soc D METHOD AND DEVICE FOR RADIACTIVE DECONTAMINATION OF A SURFACE LOCATED WITHIN A HOLLOW BODY
EP2126160A1 (en) * 2007-03-13 2009-12-02 Novo Nordisk A/S An electrolytic cip-cleaning process for removing impurities from the inner surface of a metallic container

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE704473A (en) * 1967-09-29 1968-02-01
EP0037190A1 (en) * 1980-03-10 1981-10-07 Westinghouse Electric Corporation Method of electrolytically decontaminating components of nuclear reactor system
EP0074463A1 (en) * 1981-09-12 1983-03-23 Kernforschungszentrum Karlsruhe Gmbh Method and apparatus for cleaning the inner walls of metallic tubular systems by electropolishing by means of moving electrodes
US4481090A (en) * 1984-01-23 1984-11-06 The United States Of America As Represented By The United States Department Of Energy Decontaminating metal surfaces
EP0146833A2 (en) * 1983-12-14 1985-07-03 Siemens Aktiengesellschaft Apparatus for electropolishing the inner surfaces of hollow cylindrical objects
FR2561672A1 (en) * 1984-03-21 1985-09-27 Travaux Milieu Ionisant Electrolysis device usable especially for radioactive decontamination of metal surfaces
WO1990004053A1 (en) * 1988-10-10 1990-04-19 Siemens Aktiengesellschaft Electric surface-polishing device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60174899A (en) * 1983-10-18 1985-09-09 Toshiba Corp Polishing device for metallic surface
FR2565021B1 (en) * 1984-05-25 1992-03-06 Toshiba Kk APPARATUS FOR DECONTAMINATION OF RADIOACTIVE METAL WASTE
GB2174105B (en) * 1985-03-11 1989-06-21 Oilfield Inspection Services Cleaning subsea surfaces
DE59400707D1 (en) * 1993-02-01 1996-10-31 Deco Hanulik Ag Process for decontamination of radioactive metal surfaces

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE704473A (en) * 1967-09-29 1968-02-01
EP0037190A1 (en) * 1980-03-10 1981-10-07 Westinghouse Electric Corporation Method of electrolytically decontaminating components of nuclear reactor system
EP0074463A1 (en) * 1981-09-12 1983-03-23 Kernforschungszentrum Karlsruhe Gmbh Method and apparatus for cleaning the inner walls of metallic tubular systems by electropolishing by means of moving electrodes
EP0146833A2 (en) * 1983-12-14 1985-07-03 Siemens Aktiengesellschaft Apparatus for electropolishing the inner surfaces of hollow cylindrical objects
US4481090A (en) * 1984-01-23 1984-11-06 The United States Of America As Represented By The United States Department Of Energy Decontaminating metal surfaces
FR2561672A1 (en) * 1984-03-21 1985-09-27 Travaux Milieu Ionisant Electrolysis device usable especially for radioactive decontamination of metal surfaces
WO1990004053A1 (en) * 1988-10-10 1990-04-19 Siemens Aktiengesellschaft Electric surface-polishing device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6264336B1 (en) 1999-10-22 2001-07-24 3M Innovative Properties Company Display apparatus with corrosion-resistant light directing film
US6357880B2 (en) 1999-10-22 2002-03-19 3M Innovative Properties Company Display apparatus with corrosion-resistant light directing film
US6508560B2 (en) 1999-10-22 2003-01-21 3M Innovative Properties Company Display apparatus with corrosion-resistant light directing film
US6626545B2 (en) 1999-10-22 2003-09-30 3M Innovative Properties Co Light directing construction having corrosion resistant feature

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GB2319259A (en) 1998-05-20
AU4958697A (en) 1998-06-10
GB9623953D0 (en) 1997-01-08

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