CA2084503C - Process and device for decontaminating surfaces contaminated with radioactivity - Google Patents
Process and device for decontaminating surfaces contaminated with radioactivityInfo
- Publication number
- CA2084503C CA2084503C CA002084503A CA2084503A CA2084503C CA 2084503 C CA2084503 C CA 2084503C CA 002084503 A CA002084503 A CA 002084503A CA 2084503 A CA2084503 A CA 2084503A CA 2084503 C CA2084503 C CA 2084503C
- Authority
- CA
- Canada
- Prior art keywords
- blast
- cleaning
- manipulator
- pipe
- container
- 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.)
- Expired - Lifetime
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C9/00—Appurtenances of abrasive blasting machines or devices, e.g. working chambers, arrangements for handling used abrasive material
- B24C9/006—Treatment of used abrasive material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C11/00—Selection of abrasive materials or additives for abrasive blasts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C3/00—Abrasive blasting machines or devices; Plants
- B24C3/32—Abrasive blasting machines or devices; Plants designed for abrasive blasting of particular work, e.g. the internal surfaces of cylinder blocks
- B24C3/325—Abrasive blasting machines or devices; Plants designed for abrasive blasting of particular work, e.g. the internal surfaces of cylinder blocks for internal surfaces, e.g. of tubes
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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
- G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
- G21F9/005—Decontamination of the surface of objects by ablation
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Food Science & Technology (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Cleaning In General (AREA)
- Apparatus For Disinfection Or Sterilisation (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
When cleaning contaminated surfaces of components of nuclear plant, it is important to avoid the release of radioactive aerosols into the atmosphere and to limit the amount of radioactive waste arising. The invention therefore proposes a mechanical process, using a blast-cleaning agent (4), in which the area (2) to be decontaminated is surrounded, during treatment with the jet, by a dust-tight enclosure (10) and a closed-circuit jet unit (70) is used to recycle the blast-cleaning agent. In addition, the invention includes a device for carrying out the dry decontamination process. In a preferred embodiment, this device includes a manipulator with a jet-nozzle mounted so that it can move on a hollow guide rail through which the dry-agent/dust mixture (6) produced is evacuated.
Description
2~8~a~3 The present invention relates to a procedure for decontaminating surPaces contaminated with radioactivity. ~n addition, details ar~ provided o~ apparatuses that are used to carry out the procedure.
~adioactively contaminated surfaces can lead to maintenance personnel being exposed to high levels of radiation when repair and inspection work is carried out on the systems and components that make up nuclear plant. In order to keep exposure to radiation as low as possible, it is necessary to decontaminate these surfaces before maintenance work is carried out. For example, when steam generators of nuclear power plants are being replaced, there is a need to decontaminate the exposed inner surfaces of stationary loop lines before beginning any welding work that is to be done.
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Processe~ for cleaning the components of nuclear plant, in which the surfaces of the objects to be cleaned are acted on by a blast-cleaning agent, are already known. The blast-cleaning agent that is blasted against the objects removes radioactive ~i particles, and these can be released to the atmosphere in the form of dust particles o~ aerosols.
For this reason, processes using wet agents have been proposed in order to avoid the formation of aerosols; in these processes, the particles that are removed from the surfaces are bonded to components that are added to the blast-cleaning agent, thereby avoiding the formation of an aerosol. As an example, EP-B-OO 18 ; 152 describes a process using a wet blast-cleaning process in which the surface is exposed to a jet of water to which solid particles have been added. The particles that are removed from the surface are then washed away by the jet of water, together with the solid particles, and can be collected in a c~ntainer.
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' ~i, , CA 02084~03 1998-01-22 DE-A-34 29 700 descrlbes a blast-cleanlng process ln which the surface is processed wlth dry lce to whlch a surfactant agent, for example lce partlcles or alcohol, has been added. Thls surfactant agent ls lntended to prevent the spread of radloactlve aerosols.
However, the formatlon of aerosols cannot be completely avolded, even by uslng these known processes.
Furthermore, the effectlveness of such blast treatment ls reduced because the blast-cleanlng agent that acts as an abraslve is only present ln a low concentratlon in the overall blast-cleanlng materlal. In addltlon, a large quantity of radioactive sludge ls formed, and thls can only be disposed of at great expense.
It is the task of the present invention to describe a process for decontamlnating surfaces that are contamlnated with radloactlvlty, wlth whlch the removal of a surface layer contamlnated with radioactivlty can be removed effectively and rapidly, and ln which the spread of radloactlve aerosols ln the envlronment ls prevented. Furthermore, lt is intended that the volume of the radioactive waste that is generated be kept as small as posslble. In addition, it is a further task of the present invention to describe a sultable apparatus for carrying out thls process.
Accordlng to the present invention, this is provided by a process for decontamlnatlng a surface contamlnated with radloactlvity and located within a pipe, pipe connector, or container that is open at one end, thls having the following features: a) the surface that is to be decontaminated is CA 02084~03 1998-01-22 surrounded by an enclosure that is dust-tlght to the outside, within which there ls a partlal vacuum, said enclosure being formed from the surface area that ls to be decontamlnated, a seallng element that is lntroduced lnto the pipe, the pipe connector, or into the container, and whlch separates the worklng area from the remalnlng area of the plpe, plpe connector, or contalner, and from a working cover that is installed on the open end, and is acted upon with a dry mechanlcal blast-cleaning agent; b) the blast-cleanlng agent ls supplied from a pressurlzed contalner and passed to a blast-cleanlng system that is operated with compressed gas and sealed off so as to be dust-tight to the outside; c) the blast-cleaning agent and the dust that is generated durlng the blast-cleaning process are drawn off together by a suctlon flow from the chamber, separated lnto two fractlons wlth different average graln slzes wlthln the blast-cleanlng system, and evacuated from the suctlon flow one after the other; d) the fractlon wlth the greater average graln slze ls passed contlnuously to the pressurlzed contalner for further use; e) the fractlon wlth the smaller average graln slze ls collected ln a dust collector.
More effectlve and rapld removal of the surface ls ensured by the use of a dry, mechanlcal blast-cleanlng agent.
The release of radioactive aerosols to the atmosphere ls prevented because of the fact that the surface area that ls to be decontamlnated is enclosed in a dust-tight container during the blast-cleanlng process, and because a blast-cleanlng system that ls operated wlth compres~ed gas and whlch ls also CA 02084~03 1998-01-22 enclosed so as to be dust-tlght ls used. In addltlon, the quantlty of radloactlve waste that ls generated ls reduced because of the blast-cleanlng agent recovery that ls effected ln the blast-cleanlng system and the activlty ls concentrated.
It ls preferred that the blast-cleanlng process be conducted ln the chamber, wlthln whlch there ls a partlal vacuum. Thls ls achleved ln that the suctlon flow ls ad~usted to a hlgher value than the flow of compressed gas. Because of the fact that because there wlll always be a flow that ls dlrected lnwards lnto the lnterlor of the enclosure at any posslble leakage polnts lf there ls a partlal vacuum wlthln ln the enclosure, contamlnatlon wlll be prevented from escaplng from the chamber should there be a leak at any of the seals or openings for llnes, etc.
It ls preferred that the blast-cleanlng process conslst of two steps. In the flrst step, a sharp-edged blast-cleanlng agent, for example carborundum wlth a graln slze of 100 to 300 ~. In a second step, a spherlcal blast-cleanlng agent, for example, beads of glass, stalnless steel, or nlckel alloys are used ln order to smooth the surface.
When the lnslde wall of a plpe connector that ls open at one end and connected to a plpellne ls decontamlnated, ln order to seal the plpellne off from the plpe connector, a seallng element ls lntroduced lnto the plpellne ln order to effect thls seal. Thls prevents the spread of any radloactive aerosols and the blast-cleanlng agent into the lnterlor of the plpellne. A worklng shleld ls lnstalled on the face slde of the plpe connector, and thls prevents the spread of aerosols CA 02084~03 1998-01-22 to the outslde. Thls worklng shleld contalns openlngs for the suctlon or pressure llnes that are requlred to evacuate and introduce the blast-cleanlng agent, and the means that are needed to move a manlpulator that contalns a blast-cleanlng head and whlch can move wlthln the plpe connector.
Accordlng to another aspect of the present lnventlon, there ls provlded an apparatus for decontamlnatlng a surface area that ls contamlnated wlth radloactlvlty uslng a dry mechanlcal blast-cleanlng agent and whlch ls located ln the lnterlor of a plpe, plpe connector or contalner that ls open at one end, thls havlng the followlng features: a) the apparatus contalns a manlpulator that can be moved wlthln the lnterlor of the plpe or contalner, and whlch lncorporates a blast-cleanlng head; b) the blast-cleanlng head ls connected through a pressure llne to a blast-cleanlng system that lncorporates a closed blast-cleanlng clrcult, the system belng closed off so as to be gas-tlght to the outslde and whlch ls operable wlth compressed gas from a pressurlzed contalner;
c~ the surface area that ls to be decontamlnated ls arranged wlthln an enclosure that ls dust-tlght ln whlch there ls a partlal vacuum and whlch ls formed from the surface area that ls to be decontamlnated, a seallng element that 1B lntroduced lnto the plpe, the plpe connector, or lnto the contalner and whlch separates the worklng area from the remalnlng area of the plpe, plpe connector, or contalner, and from a worklng cover that ls lnstalled on the open end; d) the enclosure ls connected through a suctlon llne to the blast-cleanlng system;
e) the suctlon llne ls connected to devlces to separate the CA 02084~03 1998-01-22 dry blast-cleanlng agent/dust mlxture lnto two fractlons wlth dlfferent graln slzes, the fractlon wlth the greater average graln slze being passed contlnuously to the pressurlzed contalner.
It ls preferred that the blast-cleanlng system lncorporate an evacuatlon system wlth a separator that separates the materlal that has been evacuated lnto two fractlons havlng dlfferent graln-slze dlstrlbutlon. In a preferred embodlment of the present lnventlon, the separator ls a centrlfugal-type separator.
An ln~ector that ls drlven by compressed alr, or a blower, ls provlded to generate the partlal vacuum that ls requlred for evacuatlon.
It ls preferred that the plpe or the contalner to be processed be sealed by means of a worklng cover that ls lnstalled on the open end so as to be dust-proof and whlch, ln a further development, lncorporates a ventllatlon openlng that ls fltted wlth a fllter. Because of thls, ln the event of lncorrect operatlon of the blast-cleanlng system, for example, ln the event of an lncorrect ad~ustment of the suctlon and compressed gas flow, the bulld-up of excesslve pressure ln the enclosure ls prevented and contamlnatlon ls prevented from reachlng the fllter.
In one conflguratlon of the present lnventlon, a plpe that can be moved axlally and whlch ls connected to the pressure llne ls provlded as the moveable manlpulator, thls - 6a -lncorporating a blast-cleanlng head on the end that ls located wlthln the enclosure. Thls embodlment ls partlcularly well sulted for use on sections of plpe or contalners that have a rectillnear mld-line axis.
- 6b -2 0 ~ 3 In a further configuration of the invention, a manipulator that moves on wheel~ within the pipe or oontainer is used, and this i~corporates a rotating blast-cleaning head. Using such a manipul~tor, it ls possible to blast-clean surfaces that are located inside aurved pipes.
A pArticularly preferred embodiment of the present invention incorporates a manipulator that is arranged so as to move in the direction of its longitudinal axis on a hollow guide rail, said manipulator incorporating a blast-cleaning head with at least one nozzle, the blast-cleaning head being arranged on the manipulator so as to be rotatable about the longitudinal axis of the guide rail. One end of the guide rail is open and its other end is connected with the suction evacuation system. As an example, the guide rail can be a pipe that incorporates a serrated bar or rack on which the decontamination manipulator can be moved backward or forwards, either electrically or pneumatically, by means of a pinion. However, a preferred version is a guide rail with a hollow profile that has two opposing flat sides that accommodate a manipulator that moves on rollers, the rollers being pressed against these flat sides by springs.
A manipulator that is guided on a central guide rail entails the advantage that curvature, degree of ovality, its diameter tolerances, conicity and its casting structure of the inside surface of the container or pipe is of little or no consequence.
Furthermore, one and the same manipulator can process pipes of different nominal widths. In the case of pipe runs that incorporate different curves, only the guide rail has to be matched to these in an appropriate manner. In addition, pipes with stepped diameters, for example, expanded or restricted sections, can be processed. This high level of adaptability to pipes of different nominal widths, and effective decontamination result in a saving of time both during installation as well as .. ..
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- - ~08~a~3 during decontamination, and thus to a reduction of the radiation do~es to which personnel are exposed.
In a pr~Perred embodiment of the lnvention, the manipulator supply lines incorporate means to maintain tension between the manlpulator and the supply lines. This prevents the formation of loops in the supply lines, for example, the electrical cable and the pressure hoses within the enclosure.
It is preferred that the manipulator contain a blast-cleaning head, the nozzle of which i5 arranged in such a way that the egress o~ the blast-cleaning agent is effected at an angle to the direction in which the manipulator advances. This angle of inclination is preferably between 30 and 60', and in particular approximately ~5~. In addition, the nozzles can be so arranged that the component that lies in the plane that is perpendicular to the direction of advance is inclined to the direction of egress of the blast-cleaning agent by approximately 45- against the radial direction.
The present invention will be described in greater detall below on the basis of embodiments shown in the drawings appended hereto. These drawings show the following:
~igure 1: an embodiment of an apparatus suitable for carrying out the process according the present invention, this being shown diagrammatically in cross section;
Figure 2: an advantageous configuration of a manipulator that is particularly suited for cleaning the inside wall of a pipe connector;
Figure 3: a particularly preferred embodiment of the present invention with a manipulator arranged so as to be moveable within the central pipe, this being shown in diagrammatic cross section;
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Figure ~: a plan view of a particularly advantageous embodiment o~ a manipulator that can be moved along the guide rall:
Fi~r~ 5: a cross seation of the embodiment shown in figure 4 in ~reater detail.
In Pigure 1, a mechanical blast-cleaning process is used to decontaminate an area 2 that is located in the interior of a pipe connector 14 that forms part of a pipe line 12, for example, a stationary loop line. To this end, the area 2 is acted upon with a blast-cleaning agent 1~ that is ejected from a blast-cleaning head 32. The blast-cleaning treatment takes place within an enclosure 10 that closes off the area 2 of the pipe connector 14 that is to be contaminated relative ~o the outside space and relative to the reactor system. In order to prevent the spread of blast-cleaning agent and dust into the reactor system, a sealing disk 16 is inserted into the pipe line 12 that is connected to reactor system. A working cover 18 is installed on the face end of the pipe connector 14 by a seal and this is ~ixed in position with the help of a clamp ring 26 that encircles the pipe connector 14.
The working cover 18 incorporates a dust-tight opening for a pipe 36 that can move axially within the pipe connector 14 and which is connected to the pressure line 22. A blast-cleaning agent 4 is introduced through the pressure line 22, and this emerges from the blast-cleaning head 32 that is arranged at the face end of the pipe 36 at an angle ~, and is then directed forcefully against the surface 2 that is to be decontaminated~ It is preferred that the angle ~ be between 30 and 60-, in particular approximately 45-. The pipe 36 and the blast-cleaning head 32 form a manipulator 30 which, in the example shown in the figure, can be moved pneumatically along a guide rail that i9 secured to the worXing cover. In the drawing this is indicated by mean~ of -a pneumatic control system that bears reference number 28.
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2~084~83 The working cover 18 also incorporates an outlet funnel 19 that acaommodates the mixture 6 of blast-cleaning agent and dust that arls~s. The outlet ~unnel 19 is connected through an opening to a s~lc~on line 20, through which the mixture 6 that con~ists of bla~t-aloaning agont and dust i5 evacuated.
During the blast-cleaning process, there is a partial vacuum in the enclosure 10 so that any escape of dust to the area outside the enclosure 10 is almost completely precluded. A manometer 17 is provided to monitor the pressure in the enclosure 10. In addition, the working cover 18 incorporates a ventilation opening 2~ that is fitted with a filter, and this prevents the build-up of an excessive pressure differential between the enclosure 10 and the outside space in the event of incorrect operation of the blast-cleaning system and also prevents the escape of any contamination.
Preparation of the blast-cleaning agent 4 and the evacuation of the blast~cleaning agent/dust mixture 6 is effected in a blast-cleaning system 70 that has a closed blast-cleaning agent circuit. Such blast-cleaning systems are described, for example, in a textbook by I. Horowitz, Oberflachenbehandlun~ mittels Strahlmitteln" ~Surface Preparation by Means of Blast-Cleaning Agents], Vol. 1, 2nd edition, 1982, p.p. 278, 279. To this end, the suction line 20 is connected to a suction system 74 that incorporates a separator 76, with which the blast-cleaning agent is separated out from the flow of dust. In the embodiment shown in this figure, a centrifugal-type separator is provided as the separator 76 and within this the mixture of blast-cleaning agent/dust 6 is separated into two fractions having different average grain sizes. The fraction with the larger grain size consists essentially of blast-cleaning agent 4 and falls, under gravity, into a supply container 80, from which it is passed to a pressurized container 72 through a drop valve. The pressurized container 72 is connected by the pressure line 22, through an ,, ~
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adjuster valve 18, to a compressor 82. The blast-cleaning agent 4 that has been recovered is introduced into the pressure line 22 throuyh a ~eod valve that is arranged in the bottom of the pr~urized container 72 and then passed to the manipulator 30.
In order to generate the partial vacuum that is required in the suation sy9~em 7~ in order to evacuate the mixture 6 of blast-cleaning agent and dust and to operate the centrifugal separator, an injector 78 that is operated by compressed gases is incorporated, and this, too, is connected through an adjuster valve 90 to the compressor 82. Between the centrifugal separator and the injector 78 there is a filter container 86 in which the compressed gas that is drawn from the injector, and which still carries radioactive dust after leaving the centrifugal separator, is cleaned by means of an aerosol filter before it is discharged to the outside environment. The dust that is passed from the centrifugal separator to the filter container 86, and which consists essentially of particles of a smaller grain size, contains both the radioactive particles that have been removed from the surface 2 and the broken-down particles of the blast-cleaning agent. Because of the enlarged cross-section at the input to the filter container, there is a reduction in the ~low velocity, and the dust settles into a dust collector 84 under the action of gravity. The dust that is separated from the suction flow is highly radioactive and can be passed on for further disposal after removal of the dust container 84. The quantity of dust that arises can be kept small, and disposal can be simplified, as a result of the recovery of the blast-cleaning agent 4.
The embodiment shown in figure 2 incorporates a manipulator 40 that moves on wheels and can be used to decontaminate curved pipe connectors 15. The moveable manipulator 40 incorporates a blast-cleaning head 42 that, in turn, incorporates two blast-cleaning ~-nozzles 44 that are inclined at an angle of approximately 45~ to the mid-line axis. The manipulator 40 is connected to the ': -, .--; i ' r.:
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pressure line 22 that passes through an appropriate opening in the working cover 18. The blast-cleaning head 42 is supported so ~ ~o bo rotatabl~ about the mid-line axis of the manipulator 40.
Th~ rotational movement can be generated by the tangential force componQnts that result when the blast-cleaning agent flows out of the blast-cleaning nozzles 44, given an appropriate arrangement of these. However, it is preferred that an electrical drlve system for the rotational movement of the blast-cleaning head 44 (not shown herein) be provi~ed for this purpose. Movement of the manipulator 40 is similarly effected by means of an electrical drive system (not shown in the drawings). The energy supply to the electrical drive systems is effected through an electrical supply cable 25 that similarly passes through the working cover 18 through a dust-tight opening. In addition, a suction connector 49 is also connected to the manipulator ~0, and the mixture 6 of blast-cleaning agent and dust that collects on the bottom of the pipe connector 15 is evacuated through this.
The embodiment shown in figure 3 incorporates a manipulator 50 that is guided on a hollow guide rail 52. The guide rail 52 is matched to the shape of the pipe connector 15 and is installed centrally within the pipe connector 15. On its end that is located within the pipe connector 15, the guide rail 52 is open.
At the other end it is connected to the suction line 20. In the example shown in the figure, the guide rail 52 is held at one end by the working cover 18 and at the other by the sealing disk 16 that is inserted into the pipeline 12. At the end of the pipe connector 15 the guide rail 52 is curved towards the inside wall of the pipe connector 15 in the area of the sealing disk 16, so that its opening is directed towards the lowest point of the pipe connector 15. The guide rail 52 is passed through the working cover 18 so as to be dust-tight, and then connected to the suction line 20. As a result of this configuration, the mixture of blast-cleaning agent and dust that connects at the lowest point of the pipe connector 15 can be evacuated ln a particularly .
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-~8~3 effective manner during the blast-cleaning process. It is pre~erred that the guide rail 52 be in the form of a hollow proPil~ with two opposing flat sides that serve to accommodate manipulator 50 that can move on rollers 58. The rollers 58 of this manipulator 50 are pressed against the flat sides o~ the ~uidc rail 52 by spring~.
The manipulator 50 supports a blast-cleaning head 42 that can rotate about the mid-line axis 53 of the guide rail 52 and which has two blast-cleaning noz21es 44 that are inclined at an angle of approximately 45~ to the mid-line axis 53 of the guide rail 52, towards the outside.
The working cover 18 incorporates devices 64 which, working through friction rollers 65 that are powered electrically or pneumatically and pressed against the pressure line 22 and against the electrical supply cable (not shown in the drawing), ensure that there is always tension between the manipulator 50 and the pressure line 22 and between the manipulator and the electrical supply cable. This ensures that no loops will be formed in the supply cable and the pressure line hose within the pipe connector 15.
It is preferred that the working cover 18 be made up of two parts 18a and 18b that are dust-tight and which can be released from each other. The part 18b that is connected to the pipe connector 15 can be easily replaced and is matched to the nominal width of the pipe connector 15 that is to be decontaminated. The part 18a, which is of a more complex ?~hAn;Cal configuration, can then be used for pipe connectors of various nominal widths. Only the shape of the hollow guide rail 52 and its dimensions need to be matched to the pipe connector 15 that is to be decontaminated.
As shown in figure 4, a manipulator 50 that can be moved axially along the guide rail 52 incorporates four rollers 58 and 59 that ~:, - 208~3 are pressed in pairs against the flat sides of the guide rail 52 by a rocker arm 57 and a spring 56. The manipulator 50 contains A bla~t-cleaning head 42 that is connected to the pressure line 22 and has two blast-cleaning nozzles 44 that are inclined at an anglc o~ 45' to the mid-line axis 53 of the guide rail 52. The bla~-cleaning head ~2 is moved in a rotational direction about the mid-line axis 53 by means of a drive system (that cannot be seen in the figure). The manipulator so is advanced along the guide rail 52 by an electrical drive system 55 that acts on a friction roller 59. The advance movement of the manipulator 50 and the rotational movement of the blast-cleaning head 42 are each detected with an electrical device 60 or 62, respectively, that measures rotational speed.
As shown in figure 5, the manipulator 50 incorporates a rotating blast-cleaning head 42 with an annular channel 45 that runs around the manipulator 50 and which is of triangular cross-section. The channel 45 is formed by a ceramic insert 46 that is opened on its face surface. The open side surface of the ceramic insert 46 is in the form of an annular ring and makes it possible to move the blast-cleaning agent from the pressure line 22 (figure 4) that is connected to the rigid part of the manipulator 50 during the overall rotational movement of the blast-cleaning head 42. The blast-cleaning agent is moved to the blast-cleaning nozzle 44 (shown in the figure only in plan view) through the channel 45. The blast-cleaning head 42 is supported within the rigid housing of the manipulator 50 so as to be rotatable, by means of sliding seals 47a, b, c, and 48. The sliding seals 47a, b, c, and 48 consist, preferably, of a ceramic material. The two sliding seals 48 that rest against the ceramic insert 46 seal the channel 45 through which the blast-cleaning agent passes against the non-rotating section of the housing of the manipulator 50.
In order to effect an adequate sealing action, the slide seals 48 are arranged on a holder 66 that is presqed by a spring 67 against the annular face surfaces of the ceramic insert 46 on the ~ .
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open side surfaces of the ceramic insert 46. The sealing sur~Aces that are formed in this way between the non-rotating sliding seals 48 and the rotating ceramic insert 46 are 5urround~d by a similarly annular-shaped hollow channel 68 on tho~r out~r edges that are remote from the channel 45. These hollow channels 68 are actèd upon by filtered compressed gas 5uch that a pressure that is slightly higher than the pressure within the channel 45 is built up within them. The sliding seals 47a and 47b prevent the compressed gas that is introduced into the hollow channel 6~ from escaping to the environment. At a working pressure within the channel 45 of, for example, approximately 6 bar, a pressure of approximately 6.2 bar is built up in the hollow channel 68. Thus, a flow of filtered compressed gas, which is directed toward~ the interior of the channel 45, is passed over the sealing surfaces between the slide seals 48 and the ceramic insert 46. As a result of this, the blast-cleaning agent is prevented from spreading into the intervening space between the slide seals 48 and the face surfaces of the ceramic insert 46. These measures bring about a distinct reduction oP
the wear on the sealing surfaces which is caused by the abrasive effect of the blast-cleaning agent. A manipulator 50 with a blast-cleaning head ~2 configured in this way can be operated for a long period of time without any need for replacement of the slide seal 48 and performance of cleaning operations. The time required for blast-cleaning, and thus the radiation doses to which operating personnel are exposed, are further reduced by the elimination of additional maintenance work on the manipulator 50 during the completion of decontamination. ' ' ':
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~adioactively contaminated surfaces can lead to maintenance personnel being exposed to high levels of radiation when repair and inspection work is carried out on the systems and components that make up nuclear plant. In order to keep exposure to radiation as low as possible, it is necessary to decontaminate these surfaces before maintenance work is carried out. For example, when steam generators of nuclear power plants are being replaced, there is a need to decontaminate the exposed inner surfaces of stationary loop lines before beginning any welding work that is to be done.
, .
Processe~ for cleaning the components of nuclear plant, in which the surfaces of the objects to be cleaned are acted on by a blast-cleaning agent, are already known. The blast-cleaning agent that is blasted against the objects removes radioactive ~i particles, and these can be released to the atmosphere in the form of dust particles o~ aerosols.
For this reason, processes using wet agents have been proposed in order to avoid the formation of aerosols; in these processes, the particles that are removed from the surfaces are bonded to components that are added to the blast-cleaning agent, thereby avoiding the formation of an aerosol. As an example, EP-B-OO 18 ; 152 describes a process using a wet blast-cleaning process in which the surface is exposed to a jet of water to which solid particles have been added. The particles that are removed from the surface are then washed away by the jet of water, together with the solid particles, and can be collected in a c~ntainer.
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' ~i, , CA 02084~03 1998-01-22 DE-A-34 29 700 descrlbes a blast-cleanlng process ln which the surface is processed wlth dry lce to whlch a surfactant agent, for example lce partlcles or alcohol, has been added. Thls surfactant agent ls lntended to prevent the spread of radloactlve aerosols.
However, the formatlon of aerosols cannot be completely avolded, even by uslng these known processes.
Furthermore, the effectlveness of such blast treatment ls reduced because the blast-cleanlng agent that acts as an abraslve is only present ln a low concentratlon in the overall blast-cleanlng materlal. In addltlon, a large quantity of radioactive sludge ls formed, and thls can only be disposed of at great expense.
It is the task of the present invention to describe a process for decontamlnating surfaces that are contamlnated with radloactlvlty, wlth whlch the removal of a surface layer contamlnated with radioactivlty can be removed effectively and rapidly, and ln which the spread of radloactlve aerosols ln the envlronment ls prevented. Furthermore, lt is intended that the volume of the radioactive waste that is generated be kept as small as posslble. In addition, it is a further task of the present invention to describe a sultable apparatus for carrying out thls process.
Accordlng to the present invention, this is provided by a process for decontamlnatlng a surface contamlnated with radloactlvity and located within a pipe, pipe connector, or container that is open at one end, thls having the following features: a) the surface that is to be decontaminated is CA 02084~03 1998-01-22 surrounded by an enclosure that is dust-tlght to the outside, within which there ls a partlal vacuum, said enclosure being formed from the surface area that ls to be decontamlnated, a seallng element that is lntroduced lnto the pipe, the pipe connector, or into the container, and whlch separates the worklng area from the remalnlng area of the plpe, plpe connector, or contalner, and from a working cover that is installed on the open end, and is acted upon with a dry mechanlcal blast-cleaning agent; b) the blast-cleanlng agent ls supplied from a pressurlzed contalner and passed to a blast-cleanlng system that is operated with compressed gas and sealed off so as to be dust-tight to the outside; c) the blast-cleaning agent and the dust that is generated durlng the blast-cleaning process are drawn off together by a suctlon flow from the chamber, separated lnto two fractlons wlth different average graln slzes wlthln the blast-cleanlng system, and evacuated from the suctlon flow one after the other; d) the fractlon wlth the greater average graln slze ls passed contlnuously to the pressurlzed contalner for further use; e) the fractlon wlth the smaller average graln slze ls collected ln a dust collector.
More effectlve and rapld removal of the surface ls ensured by the use of a dry, mechanlcal blast-cleanlng agent.
The release of radioactive aerosols to the atmosphere ls prevented because of the fact that the surface area that ls to be decontamlnated is enclosed in a dust-tight container during the blast-cleanlng process, and because a blast-cleanlng system that ls operated wlth compres~ed gas and whlch ls also CA 02084~03 1998-01-22 enclosed so as to be dust-tlght ls used. In addltlon, the quantlty of radloactlve waste that ls generated ls reduced because of the blast-cleanlng agent recovery that ls effected ln the blast-cleanlng system and the activlty ls concentrated.
It ls preferred that the blast-cleanlng process be conducted ln the chamber, wlthln whlch there ls a partlal vacuum. Thls ls achleved ln that the suctlon flow ls ad~usted to a hlgher value than the flow of compressed gas. Because of the fact that because there wlll always be a flow that ls dlrected lnwards lnto the lnterlor of the enclosure at any posslble leakage polnts lf there ls a partlal vacuum wlthln ln the enclosure, contamlnatlon wlll be prevented from escaplng from the chamber should there be a leak at any of the seals or openings for llnes, etc.
It ls preferred that the blast-cleanlng process conslst of two steps. In the flrst step, a sharp-edged blast-cleanlng agent, for example carborundum wlth a graln slze of 100 to 300 ~. In a second step, a spherlcal blast-cleanlng agent, for example, beads of glass, stalnless steel, or nlckel alloys are used ln order to smooth the surface.
When the lnslde wall of a plpe connector that ls open at one end and connected to a plpellne ls decontamlnated, ln order to seal the plpellne off from the plpe connector, a seallng element ls lntroduced lnto the plpellne ln order to effect thls seal. Thls prevents the spread of any radloactive aerosols and the blast-cleanlng agent into the lnterlor of the plpellne. A worklng shleld ls lnstalled on the face slde of the plpe connector, and thls prevents the spread of aerosols CA 02084~03 1998-01-22 to the outslde. Thls worklng shleld contalns openlngs for the suctlon or pressure llnes that are requlred to evacuate and introduce the blast-cleanlng agent, and the means that are needed to move a manlpulator that contalns a blast-cleanlng head and whlch can move wlthln the plpe connector.
Accordlng to another aspect of the present lnventlon, there ls provlded an apparatus for decontamlnatlng a surface area that ls contamlnated wlth radloactlvlty uslng a dry mechanlcal blast-cleanlng agent and whlch ls located ln the lnterlor of a plpe, plpe connector or contalner that ls open at one end, thls havlng the followlng features: a) the apparatus contalns a manlpulator that can be moved wlthln the lnterlor of the plpe or contalner, and whlch lncorporates a blast-cleanlng head; b) the blast-cleanlng head ls connected through a pressure llne to a blast-cleanlng system that lncorporates a closed blast-cleanlng clrcult, the system belng closed off so as to be gas-tlght to the outslde and whlch ls operable wlth compressed gas from a pressurlzed contalner;
c~ the surface area that ls to be decontamlnated ls arranged wlthln an enclosure that ls dust-tlght ln whlch there ls a partlal vacuum and whlch ls formed from the surface area that ls to be decontamlnated, a seallng element that 1B lntroduced lnto the plpe, the plpe connector, or lnto the contalner and whlch separates the worklng area from the remalnlng area of the plpe, plpe connector, or contalner, and from a worklng cover that ls lnstalled on the open end; d) the enclosure ls connected through a suctlon llne to the blast-cleanlng system;
e) the suctlon llne ls connected to devlces to separate the CA 02084~03 1998-01-22 dry blast-cleanlng agent/dust mlxture lnto two fractlons wlth dlfferent graln slzes, the fractlon wlth the greater average graln slze being passed contlnuously to the pressurlzed contalner.
It ls preferred that the blast-cleanlng system lncorporate an evacuatlon system wlth a separator that separates the materlal that has been evacuated lnto two fractlons havlng dlfferent graln-slze dlstrlbutlon. In a preferred embodlment of the present lnventlon, the separator ls a centrlfugal-type separator.
An ln~ector that ls drlven by compressed alr, or a blower, ls provlded to generate the partlal vacuum that ls requlred for evacuatlon.
It ls preferred that the plpe or the contalner to be processed be sealed by means of a worklng cover that ls lnstalled on the open end so as to be dust-proof and whlch, ln a further development, lncorporates a ventllatlon openlng that ls fltted wlth a fllter. Because of thls, ln the event of lncorrect operatlon of the blast-cleanlng system, for example, ln the event of an lncorrect ad~ustment of the suctlon and compressed gas flow, the bulld-up of excesslve pressure ln the enclosure ls prevented and contamlnatlon ls prevented from reachlng the fllter.
In one conflguratlon of the present lnventlon, a plpe that can be moved axlally and whlch ls connected to the pressure llne ls provlded as the moveable manlpulator, thls - 6a -lncorporating a blast-cleanlng head on the end that ls located wlthln the enclosure. Thls embodlment ls partlcularly well sulted for use on sections of plpe or contalners that have a rectillnear mld-line axis.
- 6b -2 0 ~ 3 In a further configuration of the invention, a manipulator that moves on wheel~ within the pipe or oontainer is used, and this i~corporates a rotating blast-cleaning head. Using such a manipul~tor, it ls possible to blast-clean surfaces that are located inside aurved pipes.
A pArticularly preferred embodiment of the present invention incorporates a manipulator that is arranged so as to move in the direction of its longitudinal axis on a hollow guide rail, said manipulator incorporating a blast-cleaning head with at least one nozzle, the blast-cleaning head being arranged on the manipulator so as to be rotatable about the longitudinal axis of the guide rail. One end of the guide rail is open and its other end is connected with the suction evacuation system. As an example, the guide rail can be a pipe that incorporates a serrated bar or rack on which the decontamination manipulator can be moved backward or forwards, either electrically or pneumatically, by means of a pinion. However, a preferred version is a guide rail with a hollow profile that has two opposing flat sides that accommodate a manipulator that moves on rollers, the rollers being pressed against these flat sides by springs.
A manipulator that is guided on a central guide rail entails the advantage that curvature, degree of ovality, its diameter tolerances, conicity and its casting structure of the inside surface of the container or pipe is of little or no consequence.
Furthermore, one and the same manipulator can process pipes of different nominal widths. In the case of pipe runs that incorporate different curves, only the guide rail has to be matched to these in an appropriate manner. In addition, pipes with stepped diameters, for example, expanded or restricted sections, can be processed. This high level of adaptability to pipes of different nominal widths, and effective decontamination result in a saving of time both during installation as well as .. ..
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- - ~08~a~3 during decontamination, and thus to a reduction of the radiation do~es to which personnel are exposed.
In a pr~Perred embodiment of the lnvention, the manipulator supply lines incorporate means to maintain tension between the manlpulator and the supply lines. This prevents the formation of loops in the supply lines, for example, the electrical cable and the pressure hoses within the enclosure.
It is preferred that the manipulator contain a blast-cleaning head, the nozzle of which i5 arranged in such a way that the egress o~ the blast-cleaning agent is effected at an angle to the direction in which the manipulator advances. This angle of inclination is preferably between 30 and 60', and in particular approximately ~5~. In addition, the nozzles can be so arranged that the component that lies in the plane that is perpendicular to the direction of advance is inclined to the direction of egress of the blast-cleaning agent by approximately 45- against the radial direction.
The present invention will be described in greater detall below on the basis of embodiments shown in the drawings appended hereto. These drawings show the following:
~igure 1: an embodiment of an apparatus suitable for carrying out the process according the present invention, this being shown diagrammatically in cross section;
Figure 2: an advantageous configuration of a manipulator that is particularly suited for cleaning the inside wall of a pipe connector;
Figure 3: a particularly preferred embodiment of the present invention with a manipulator arranged so as to be moveable within the central pipe, this being shown in diagrammatic cross section;
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Figure ~: a plan view of a particularly advantageous embodiment o~ a manipulator that can be moved along the guide rall:
Fi~r~ 5: a cross seation of the embodiment shown in figure 4 in ~reater detail.
In Pigure 1, a mechanical blast-cleaning process is used to decontaminate an area 2 that is located in the interior of a pipe connector 14 that forms part of a pipe line 12, for example, a stationary loop line. To this end, the area 2 is acted upon with a blast-cleaning agent 1~ that is ejected from a blast-cleaning head 32. The blast-cleaning treatment takes place within an enclosure 10 that closes off the area 2 of the pipe connector 14 that is to be contaminated relative ~o the outside space and relative to the reactor system. In order to prevent the spread of blast-cleaning agent and dust into the reactor system, a sealing disk 16 is inserted into the pipe line 12 that is connected to reactor system. A working cover 18 is installed on the face end of the pipe connector 14 by a seal and this is ~ixed in position with the help of a clamp ring 26 that encircles the pipe connector 14.
The working cover 18 incorporates a dust-tight opening for a pipe 36 that can move axially within the pipe connector 14 and which is connected to the pressure line 22. A blast-cleaning agent 4 is introduced through the pressure line 22, and this emerges from the blast-cleaning head 32 that is arranged at the face end of the pipe 36 at an angle ~, and is then directed forcefully against the surface 2 that is to be decontaminated~ It is preferred that the angle ~ be between 30 and 60-, in particular approximately 45-. The pipe 36 and the blast-cleaning head 32 form a manipulator 30 which, in the example shown in the figure, can be moved pneumatically along a guide rail that i9 secured to the worXing cover. In the drawing this is indicated by mean~ of -a pneumatic control system that bears reference number 28.
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2~084~83 The working cover 18 also incorporates an outlet funnel 19 that acaommodates the mixture 6 of blast-cleaning agent and dust that arls~s. The outlet ~unnel 19 is connected through an opening to a s~lc~on line 20, through which the mixture 6 that con~ists of bla~t-aloaning agont and dust i5 evacuated.
During the blast-cleaning process, there is a partial vacuum in the enclosure 10 so that any escape of dust to the area outside the enclosure 10 is almost completely precluded. A manometer 17 is provided to monitor the pressure in the enclosure 10. In addition, the working cover 18 incorporates a ventilation opening 2~ that is fitted with a filter, and this prevents the build-up of an excessive pressure differential between the enclosure 10 and the outside space in the event of incorrect operation of the blast-cleaning system and also prevents the escape of any contamination.
Preparation of the blast-cleaning agent 4 and the evacuation of the blast~cleaning agent/dust mixture 6 is effected in a blast-cleaning system 70 that has a closed blast-cleaning agent circuit. Such blast-cleaning systems are described, for example, in a textbook by I. Horowitz, Oberflachenbehandlun~ mittels Strahlmitteln" ~Surface Preparation by Means of Blast-Cleaning Agents], Vol. 1, 2nd edition, 1982, p.p. 278, 279. To this end, the suction line 20 is connected to a suction system 74 that incorporates a separator 76, with which the blast-cleaning agent is separated out from the flow of dust. In the embodiment shown in this figure, a centrifugal-type separator is provided as the separator 76 and within this the mixture of blast-cleaning agent/dust 6 is separated into two fractions having different average grain sizes. The fraction with the larger grain size consists essentially of blast-cleaning agent 4 and falls, under gravity, into a supply container 80, from which it is passed to a pressurized container 72 through a drop valve. The pressurized container 72 is connected by the pressure line 22, through an ,, ~
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adjuster valve 18, to a compressor 82. The blast-cleaning agent 4 that has been recovered is introduced into the pressure line 22 throuyh a ~eod valve that is arranged in the bottom of the pr~urized container 72 and then passed to the manipulator 30.
In order to generate the partial vacuum that is required in the suation sy9~em 7~ in order to evacuate the mixture 6 of blast-cleaning agent and dust and to operate the centrifugal separator, an injector 78 that is operated by compressed gases is incorporated, and this, too, is connected through an adjuster valve 90 to the compressor 82. Between the centrifugal separator and the injector 78 there is a filter container 86 in which the compressed gas that is drawn from the injector, and which still carries radioactive dust after leaving the centrifugal separator, is cleaned by means of an aerosol filter before it is discharged to the outside environment. The dust that is passed from the centrifugal separator to the filter container 86, and which consists essentially of particles of a smaller grain size, contains both the radioactive particles that have been removed from the surface 2 and the broken-down particles of the blast-cleaning agent. Because of the enlarged cross-section at the input to the filter container, there is a reduction in the ~low velocity, and the dust settles into a dust collector 84 under the action of gravity. The dust that is separated from the suction flow is highly radioactive and can be passed on for further disposal after removal of the dust container 84. The quantity of dust that arises can be kept small, and disposal can be simplified, as a result of the recovery of the blast-cleaning agent 4.
The embodiment shown in figure 2 incorporates a manipulator 40 that moves on wheels and can be used to decontaminate curved pipe connectors 15. The moveable manipulator 40 incorporates a blast-cleaning head 42 that, in turn, incorporates two blast-cleaning ~-nozzles 44 that are inclined at an angle of approximately 45~ to the mid-line axis. The manipulator 40 is connected to the ': -, .--; i ' r.:
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pressure line 22 that passes through an appropriate opening in the working cover 18. The blast-cleaning head 42 is supported so ~ ~o bo rotatabl~ about the mid-line axis of the manipulator 40.
Th~ rotational movement can be generated by the tangential force componQnts that result when the blast-cleaning agent flows out of the blast-cleaning nozzles 44, given an appropriate arrangement of these. However, it is preferred that an electrical drlve system for the rotational movement of the blast-cleaning head 44 (not shown herein) be provi~ed for this purpose. Movement of the manipulator 40 is similarly effected by means of an electrical drive system (not shown in the drawings). The energy supply to the electrical drive systems is effected through an electrical supply cable 25 that similarly passes through the working cover 18 through a dust-tight opening. In addition, a suction connector 49 is also connected to the manipulator ~0, and the mixture 6 of blast-cleaning agent and dust that collects on the bottom of the pipe connector 15 is evacuated through this.
The embodiment shown in figure 3 incorporates a manipulator 50 that is guided on a hollow guide rail 52. The guide rail 52 is matched to the shape of the pipe connector 15 and is installed centrally within the pipe connector 15. On its end that is located within the pipe connector 15, the guide rail 52 is open.
At the other end it is connected to the suction line 20. In the example shown in the figure, the guide rail 52 is held at one end by the working cover 18 and at the other by the sealing disk 16 that is inserted into the pipeline 12. At the end of the pipe connector 15 the guide rail 52 is curved towards the inside wall of the pipe connector 15 in the area of the sealing disk 16, so that its opening is directed towards the lowest point of the pipe connector 15. The guide rail 52 is passed through the working cover 18 so as to be dust-tight, and then connected to the suction line 20. As a result of this configuration, the mixture of blast-cleaning agent and dust that connects at the lowest point of the pipe connector 15 can be evacuated ln a particularly .
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-~8~3 effective manner during the blast-cleaning process. It is pre~erred that the guide rail 52 be in the form of a hollow proPil~ with two opposing flat sides that serve to accommodate manipulator 50 that can move on rollers 58. The rollers 58 of this manipulator 50 are pressed against the flat sides o~ the ~uidc rail 52 by spring~.
The manipulator 50 supports a blast-cleaning head 42 that can rotate about the mid-line axis 53 of the guide rail 52 and which has two blast-cleaning noz21es 44 that are inclined at an angle of approximately 45~ to the mid-line axis 53 of the guide rail 52, towards the outside.
The working cover 18 incorporates devices 64 which, working through friction rollers 65 that are powered electrically or pneumatically and pressed against the pressure line 22 and against the electrical supply cable (not shown in the drawing), ensure that there is always tension between the manipulator 50 and the pressure line 22 and between the manipulator and the electrical supply cable. This ensures that no loops will be formed in the supply cable and the pressure line hose within the pipe connector 15.
It is preferred that the working cover 18 be made up of two parts 18a and 18b that are dust-tight and which can be released from each other. The part 18b that is connected to the pipe connector 15 can be easily replaced and is matched to the nominal width of the pipe connector 15 that is to be decontaminated. The part 18a, which is of a more complex ?~hAn;Cal configuration, can then be used for pipe connectors of various nominal widths. Only the shape of the hollow guide rail 52 and its dimensions need to be matched to the pipe connector 15 that is to be decontaminated.
As shown in figure 4, a manipulator 50 that can be moved axially along the guide rail 52 incorporates four rollers 58 and 59 that ~:, - 208~3 are pressed in pairs against the flat sides of the guide rail 52 by a rocker arm 57 and a spring 56. The manipulator 50 contains A bla~t-cleaning head 42 that is connected to the pressure line 22 and has two blast-cleaning nozzles 44 that are inclined at an anglc o~ 45' to the mid-line axis 53 of the guide rail 52. The bla~-cleaning head ~2 is moved in a rotational direction about the mid-line axis 53 by means of a drive system (that cannot be seen in the figure). The manipulator so is advanced along the guide rail 52 by an electrical drive system 55 that acts on a friction roller 59. The advance movement of the manipulator 50 and the rotational movement of the blast-cleaning head 42 are each detected with an electrical device 60 or 62, respectively, that measures rotational speed.
As shown in figure 5, the manipulator 50 incorporates a rotating blast-cleaning head 42 with an annular channel 45 that runs around the manipulator 50 and which is of triangular cross-section. The channel 45 is formed by a ceramic insert 46 that is opened on its face surface. The open side surface of the ceramic insert 46 is in the form of an annular ring and makes it possible to move the blast-cleaning agent from the pressure line 22 (figure 4) that is connected to the rigid part of the manipulator 50 during the overall rotational movement of the blast-cleaning head 42. The blast-cleaning agent is moved to the blast-cleaning nozzle 44 (shown in the figure only in plan view) through the channel 45. The blast-cleaning head 42 is supported within the rigid housing of the manipulator 50 so as to be rotatable, by means of sliding seals 47a, b, c, and 48. The sliding seals 47a, b, c, and 48 consist, preferably, of a ceramic material. The two sliding seals 48 that rest against the ceramic insert 46 seal the channel 45 through which the blast-cleaning agent passes against the non-rotating section of the housing of the manipulator 50.
In order to effect an adequate sealing action, the slide seals 48 are arranged on a holder 66 that is presqed by a spring 67 against the annular face surfaces of the ceramic insert 46 on the ~ .
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open side surfaces of the ceramic insert 46. The sealing sur~Aces that are formed in this way between the non-rotating sliding seals 48 and the rotating ceramic insert 46 are 5urround~d by a similarly annular-shaped hollow channel 68 on tho~r out~r edges that are remote from the channel 45. These hollow channels 68 are actèd upon by filtered compressed gas 5uch that a pressure that is slightly higher than the pressure within the channel 45 is built up within them. The sliding seals 47a and 47b prevent the compressed gas that is introduced into the hollow channel 6~ from escaping to the environment. At a working pressure within the channel 45 of, for example, approximately 6 bar, a pressure of approximately 6.2 bar is built up in the hollow channel 68. Thus, a flow of filtered compressed gas, which is directed toward~ the interior of the channel 45, is passed over the sealing surfaces between the slide seals 48 and the ceramic insert 46. As a result of this, the blast-cleaning agent is prevented from spreading into the intervening space between the slide seals 48 and the face surfaces of the ceramic insert 46. These measures bring about a distinct reduction oP
the wear on the sealing surfaces which is caused by the abrasive effect of the blast-cleaning agent. A manipulator 50 with a blast-cleaning head ~2 configured in this way can be operated for a long period of time without any need for replacement of the slide seal 48 and performance of cleaning operations. The time required for blast-cleaning, and thus the radiation doses to which operating personnel are exposed, are further reduced by the elimination of additional maintenance work on the manipulator 50 during the completion of decontamination. ' ' ':
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Claims (22)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for decontaminating a surface contaminated with radioactivity and located within a pipe, pipe connector, or container that is open at one end, this having the following features:
a) the surface that is to be decontaminated is surrounded by an enclosure that is dust-tight to the outside, within which is a partial vacuum, said enclosure being formed from the surface area that is to be decontaminated, a sealing element that is introduced into the pipe, the pipe connector, or into the container, and which separates the working area from the remaining area of the pipe, pipe connector, or container, and from a working cover that is installed on the open end, and is acted upon with a dry mechanical blast-cleaning agent;
b) the blast-cleaning agent is supplied from a pressurized container and passed to a blast-cleaning system that is operated with compressed gas and sealed off so as to be dust-tight to the outside;
c) the blast-cleaning agent and the dust that is generated during the blast-cleaning process are drawn off together by a suction flow from the chamber, separated into two fractions with different average grain sizes within the blast-cleaning system, and evacuated from the suction flow one after the other;
d) the fraction with the greater average grain size is passed continuously to the pressurized container for further use;
e) the fraction with the smaller average grain size is collected in a dust collector.
a) the surface that is to be decontaminated is surrounded by an enclosure that is dust-tight to the outside, within which is a partial vacuum, said enclosure being formed from the surface area that is to be decontaminated, a sealing element that is introduced into the pipe, the pipe connector, or into the container, and which separates the working area from the remaining area of the pipe, pipe connector, or container, and from a working cover that is installed on the open end, and is acted upon with a dry mechanical blast-cleaning agent;
b) the blast-cleaning agent is supplied from a pressurized container and passed to a blast-cleaning system that is operated with compressed gas and sealed off so as to be dust-tight to the outside;
c) the blast-cleaning agent and the dust that is generated during the blast-cleaning process are drawn off together by a suction flow from the chamber, separated into two fractions with different average grain sizes within the blast-cleaning system, and evacuated from the suction flow one after the other;
d) the fraction with the greater average grain size is passed continuously to the pressurized container for further use;
e) the fraction with the smaller average grain size is collected in a dust collector.
2. A process as defined in claim 1, characterized in that during a first stage in the process the blast-cleaning process is carried out with a sharp-edged blast-cleaning agent and, in a second process step, with a spherical blast-cleaning agent.
3. A process as defined in one of the preceding claims, characterized in that the working cover contains openings for the suction or pressure lines, respectively, that are needed to evacuate and to supply the blast-cleaning agent, and the means that are needed to move a manipulator that incorporates a blast-cleaning head and which can be moved within the pipe connector.
4. An apparatus for decontaminating a surface area that is contaminated with radioactivity using a dry mechanical blast-cleaning agent and which is located in the interior of a pipe, pipe connector or container that is open at one end, this having the following features a) the apparatus contains a manipulator that can be moved within the interior of the pipe or container, and which incorporates a blast-cleaning head;
b) the blast-cleaning head is connected through a pressure line to a blast-cleaning system that incorporates a closed blast-cleaning circuit, the system being closed off so as to be gas-tight to the outside and which is operable with compressed gas from a pressurized container;
c) the surface area that is to be decontaminated is arranged within an enclosure that is dust-tight in which there is a partial vacuum and which is formed from the surface area that is to be decontaminated, a sealing element that is introduced into the pipe, the pipe connector, or into the container and which separates the working area from the remaining area of the pipe, pipe connector, or container, and from a working cover that is installed on the open end;
d) the enclosure is connected through a suction line to the blast-cleaning system;
e) the suction line is connected to devices to separate the dry blast-cleaning agent/dust mixture into two fractions with different grain sizes, the fraction with the greater average grain size being passed continuously to the pressurized container.
b) the blast-cleaning head is connected through a pressure line to a blast-cleaning system that incorporates a closed blast-cleaning circuit, the system being closed off so as to be gas-tight to the outside and which is operable with compressed gas from a pressurized container;
c) the surface area that is to be decontaminated is arranged within an enclosure that is dust-tight in which there is a partial vacuum and which is formed from the surface area that is to be decontaminated, a sealing element that is introduced into the pipe, the pipe connector, or into the container and which separates the working area from the remaining area of the pipe, pipe connector, or container, and from a working cover that is installed on the open end;
d) the enclosure is connected through a suction line to the blast-cleaning system;
e) the suction line is connected to devices to separate the dry blast-cleaning agent/dust mixture into two fractions with different grain sizes, the fraction with the greater average grain size being passed continuously to the pressurized container.
5. An apparatus as defined in claim 4, characterized in that the blast-cleaning system incorporates a separator for separating the material that has been evacuated into two fractions with different grain size distribution.
6. An apparatus as defined in claim 5, characterized in that a centrifugal separator is provided as the separator.
7. An apparatus as defined in claim 6, characterized in that the blast-cleaning system incorporates an ejector, which is driven by compressed air, and which is used to generate a partial vacuum.
8. An apparatus as defined in claim 6, characterized in that a blower is used to generate the partial vacuum.
9. An apparatus as defined in one of the claims 4 to 8, characterized in that it incorporates a working cover that can be installed so as to be dust-tight on the open end of the pipe or container that is to be processed.
10. An apparatus as defined in claim 9, characterized in that the working cover contains a ventilation opening that is fitted with a filter.
11. An apparatus as defined in one of the claims 4 to 10 characterized in that the blast-cleaning head is arranged on a pipe that can be moved axially and is connected with the pressure line.
12. An apparatus as defined in one of the claims 4 to 10, characterized in that the blast-cleaning head is arranged so as to be rotatable on a manipulator that can move on wheels within the pipe or container and is connected to a pressure line.
13. An apparatus as defined in claim 12, characterized in that the manipulator is connected to a suction line.
14. An apparatus as defined in one of the claims 4 to 10, characterized in that it incorporates a manipulator that is arranged so as to be able to move on a hollow guide rail in the direction of its mid-line axis, this manipulator incorporating a blast-cleaning head with at least one blast-cleaning nozzle, the blast-cleaning head being arranged on the manipulator so as to be rotatable about the mid-line axis of the guide rail, the guide rail being open at one end, and, at its other end, being connected to the suction line.
15. An apparatus as defined in claim 14, characterized in that the guide rail has a hollow profile with two opposing flat sides that accommodate a manipulator with rollers that can be pressed against these flat sides.
16. An apparatus as defined in one of the claims 14 or 15, characterized in that it incorporates a device to determine the advancing movement of the manipulator.
17. An apparatus as defined in one of the claims 14 to 16 characterized in that it incorporates a device to determine the rotational movement of the blast-cleaning head.
18. An apparatus as defined in one of the claims 14 to 17, characterized in that means to maintain tension between the manipulator and the supply lines are provided for the supply lines.
19. An apparatus as defined in one of the claims 14 to 18, characterized in that the blast-cleaning nozzles are arranged such that the blast-cleaning agent is discharged at an angle to the direction of advance.
20. An apparatus as defined in claim 19, characterized in that the angle of this inclination is between 30 and 60°.
21. An apparatus as defined in one of the claims 14 to 20, characterized in that the blast-cleaning nozzles are arranged such that the components lying in a plane that is perpendicular to the direction of advance are inclined at approximately 45° in the radial direction to the direction of efflux of the blast-cleaning agent.
22. An apparatus as defined in one of the claims 14 to 21 with a manipulator having the following features:
a) the manipulator incorporates a blast-cleaning head with a channel so as to be rotatable through slide seals;
b) the channel is connected with a section of the slide seals;
c) the manipulator contains means to maintain a flow of filtered compressed gas through the sealing surfaces formed by these slide seals, this flow being directed into the channel.
a) the manipulator incorporates a blast-cleaning head with a channel so as to be rotatable through slide seals;
b) the channel is connected with a section of the slide seals;
c) the manipulator contains means to maintain a flow of filtered compressed gas through the sealing surfaces formed by these slide seals, this flow being directed into the channel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4017998A DE4017998A1 (en) | 1990-06-05 | 1990-06-05 | METHOD AND DEVICE FOR DECONTAMINATING RADIOACTIVELY CONTAMINATED SURFACES |
| DEP4017998.2 | 1990-06-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2084503A1 CA2084503A1 (en) | 1991-12-06 |
| CA2084503C true CA2084503C (en) | 1998-09-15 |
Family
ID=6407819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002084503A Expired - Lifetime CA2084503C (en) | 1990-06-05 | 1991-05-29 | Process and device for decontaminating surfaces contaminated with radioactivity |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0532544B1 (en) |
| JP (1) | JPH05507557A (en) |
| CA (1) | CA2084503C (en) |
| DE (2) | DE4017998A1 (en) |
| ES (1) | ES2065037T3 (en) |
| WO (1) | WO1991018712A2 (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0639718A (en) * | 1992-03-13 | 1994-02-15 | Westinghouse Electric Corp <We> | Method and device for continuous shot peening of small tube of steam generator |
| DE4227309A1 (en) * | 1992-08-18 | 1994-02-24 | Harm Willem Holman | Method for preparing the demolition or destruction of buildings and the like and device for applying the method |
| DE59208832D1 (en) * | 1992-10-21 | 1997-10-02 | Piatti Alfredo Ag | Method and device for cleaning surfaces, in particular masonry |
| JPH06246636A (en) * | 1993-02-26 | 1994-09-06 | Eikichi Yamaharu | Blasting device and metallic mold finishing device using the same |
| DE4306631A1 (en) * | 1993-03-03 | 1994-09-08 | Siemens Ag | Device for the decontamination of radioactive contaminated surfaces |
| DE4319095C2 (en) * | 1993-06-08 | 1995-04-20 | Siemens Ag | Device for decontaminating a radioactive contaminated surface |
| US5601479A (en) * | 1994-09-28 | 1997-02-11 | Santos; Eugene W. | Method and apparatus for decontaminating structures |
| DE19521236C2 (en) * | 1995-06-10 | 1999-08-05 | Nukem Gmbh | Process for decontaminating the boundaries of closed areas |
| WO1998058768A1 (en) * | 1997-06-20 | 1998-12-30 | Gevi Gesellschaft Für Entwicklung Und Vertrieb Industrieller, Zerstörungsfreier Und Umweltfreundlicher Verfahrenstechniken Zur Innensanierung Von Rohrleitungen Mbh | Method for cleaning pipes using dry ice |
| 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 |
| DE102005001700A1 (en) * | 2005-01-13 | 2006-07-27 | Julius-Maximilians-Universität Würzburg | Instrument cleaning device for treatment instruments |
| DE102006016314B3 (en) * | 2006-04-06 | 2007-09-20 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Jet spray tool for the production of a jet of carbon dioxide snow for dry cleaning of tube cavity, has hose-shaped shaft, carbon dioxide jet nozzle and inlet line for carbon dioxide, which is attached to the nozzle and runs along the shaft |
| EP2497601B1 (en) * | 2011-03-07 | 2014-11-12 | Foure Lagadec | System for treating an inner surface of a conduit by spraying particles |
| EP2514562A1 (en) * | 2011-04-21 | 2012-10-24 | Zinguerie Sablage Metallisation S.A. | Device and method for sandblasting a pipe |
| RU2695630C1 (en) * | 2018-10-23 | 2019-07-25 | Акционерное Общество "Российский Концерн По Производству Электрической И Тепловой Энергии На Атомных Станциях" (Ао "Концерн Росэнергоатом") | Device for decontamination of radioactive elements |
| DE102020120666B3 (en) * | 2020-04-30 | 2021-02-04 | Kompass Holding GbR Marc Schulte & Miriam Schulte (vertretungsberechtigter Gesellschafter: Miriam Schulte, 33739 Bielefeld) | Method for removing a large area of a contaminated plastic coating from a building made of concrete or masonry |
| DE102020118183A1 (en) | 2020-07-09 | 2022-01-13 | Bilfinger EMS GmbH | Method for decontaminating metal surfaces and decontamination device |
| CN115256249B (en) * | 2022-09-29 | 2022-12-09 | 达州市全锦建材有限责任公司 | Shot blasting machine |
Family Cites Families (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2348505A (en) * | 1943-09-24 | 1944-05-09 | Voerge John Nicholas | Sandblasting |
| DE1031172B (en) * | 1954-04-01 | 1958-05-29 | William Howard Mead | Device for surface treatment |
| DE1173235B (en) * | 1954-08-03 | 1964-07-02 | Heinze Fa R | Process for the production of key buttons made of plastic with a light-refracting tactile surface |
| GB874720A (en) * | 1959-05-05 | 1961-08-10 | Henry Cobden Turner | Improvements in or relating to the treatment of leather or plastic articles |
| CH382016A (en) * | 1960-12-29 | 1964-09-15 | Entrag Ag | Device for sandblasting the inner surface of pipelines |
| US3188776A (en) * | 1962-08-20 | 1965-06-15 | Wheelabrator Corp | Surface treatment of steel |
| US3571985A (en) * | 1965-10-20 | 1971-03-23 | Capvac Ind Inc | Cylinder treating method |
| US3485671A (en) * | 1966-12-19 | 1969-12-23 | Food Products Inc | Method of cleaning air supply systems and ducts |
| CH489333A (en) * | 1968-04-27 | 1970-04-30 | Schlick Kg Heinrich | Device for sorting and separating the blasting dust present in closed blasting systems |
| GB1263799A (en) * | 1969-09-02 | 1972-02-16 | Vacu Blast Ltd | A dust separator system for a dust creating process |
| DE2107479C3 (en) * | 1971-02-17 | 1974-01-03 | Siemens Ag, 1000 Berlin U. 8000 Muenchen | Process for the decontamination of the surfaces of nuclear reactor components |
| KR840002298B1 (en) * | 1980-01-30 | 1984-12-15 | 웨스팅하우스일렉트릭 코오포레이숀 | Manipulator control system and apparatus for decontaminating nuclear steam generators |
| DK153529C (en) * | 1980-05-01 | 1988-12-12 | Ao Eng As | CLEANING AGENT FOR CLEANING THE INTERNAL SURFACE OF A CONTAINER |
| US4603515A (en) * | 1980-12-22 | 1986-08-05 | The United States Of America As Represented By The Secretary Of The Air Force | Vacuum blast adapter for bombs |
| JPS59174735A (en) * | 1983-03-25 | 1984-10-03 | Toshiba Corp | Method and apparatus for decontaminating equipment contaminated by radioactivity |
| US4655847A (en) * | 1983-09-01 | 1987-04-07 | Tsuyoshi Ichinoseki | Cleaning method |
| DE3345278A1 (en) * | 1983-12-14 | 1985-06-27 | Kraftwerk Union AG, 4330 Mülheim | DEVICE FOR ELECTROPOLISHING THE INTERNAL SURFACE OF HOLLOW CYLINDRICAL BODIES |
| DE3408828A1 (en) * | 1984-03-10 | 1985-09-12 | Rudolf 4834 Harsewinkel Ristow | Method for cleaning surfaces, in particular inner surfaces of ventilation systems and system parts |
| EP0234365A1 (en) * | 1986-02-21 | 1987-09-02 | Balduf Verfahrenstechnik GmbH | Device for abrasive surface treatment |
| US4993200A (en) * | 1986-03-11 | 1991-02-19 | Kawasaki Steel Techno-Research Corp | Pollution free blaster system and blaster head therefor |
| DE3711826A1 (en) * | 1987-04-08 | 1988-10-27 | Meuwsen & Brockhausen | Method of repairing hydraulic cylinders |
| DE3720992A1 (en) * | 1987-06-25 | 1989-01-05 | Nusec Gmbh | Method and facility for abrasive blasting of surfaces, in particular of contaminated surfaces |
| GB2221274B (en) * | 1988-07-26 | 1992-08-05 | Decosafe Uk Limited | Apparatus and methods for de-scaling pipes |
-
1990
- 1990-06-05 DE DE4017998A patent/DE4017998A1/en active Granted
-
1991
- 1991-05-29 WO PCT/DE1991/000460 patent/WO1991018712A2/en active IP Right Grant
- 1991-05-29 JP JP91509699A patent/JPH05507557A/en active Pending
- 1991-05-29 CA CA002084503A patent/CA2084503C/en not_active Expired - Lifetime
- 1991-05-29 ES ES91909905T patent/ES2065037T3/en not_active Expired - Lifetime
- 1991-05-29 DE DE59103824T patent/DE59103824D1/en not_active Expired - Lifetime
- 1991-05-29 EP EP91909905A patent/EP0532544B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE4017998A1 (en) | 1992-01-09 |
| WO1991018712A3 (en) | 1992-10-29 |
| WO1991018712A2 (en) | 1991-12-12 |
| EP0532544A1 (en) | 1993-03-24 |
| CA2084503A1 (en) | 1991-12-06 |
| JPH05507557A (en) | 1993-10-28 |
| DE4017998C2 (en) | 1993-03-25 |
| ES2065037T3 (en) | 1995-02-01 |
| DE59103824D1 (en) | 1995-01-19 |
| EP0532544B1 (en) | 1994-12-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |