DE2944880A1 - Radioactive decontamination uses gas jets - in closed circuit contg. gas purification. plant followed by particle bombardment - Google Patents

Abstract

Method of surface cleaning objects, esp those polluted by radioactivity, consists of gas-jetting the objects in a closed system, in which the gas is simultaneously passed through a drying and purifying plant. After gas jetting, the gas is evacuated to a sufficient vacuum for glow discharge and then the objects are subjected to a further surface treatment by gas discharge using ions and/or electron bombardment. Pref argon or nitrogen are used for the gas. More than one jetting operation using the same or different gases may be used. Used in particular for cleaning objects that have been stored or in use as equipment in radioactive environments. The method is simpler than traditional washing processes, and is esp suitable for complicated equipment, such as gear wheels, where liq washing requires considerable manual work.

Description

description

The invention relates to a method and a device for surface cleaning of objects, in particular radioactive contaminated objects.

Handling and storage of objects in an unclean environment leads to their contamination. For example Tools stored in radioactive contaminated rooms or used for processing radioactive substances are radioactive contaminated. The same also applies to containers used for the transport and / or storage of radioactive substances or radioactively contaminated substances are used.

It is known to remove surface contaminated objects by manual and / or machine treatment, such as washing and scrubbing with various solvents and abrasives. Occasionally, objects are used to remove surface contaminants, such as tritium contaminants, heated to a high temperature of, for example, 400 ° C with the result that the impurities evaporate.

The known cleaning methods have the major disadvantage that they are quite costly when carried out manually and when carried out by machine only for objects with a simple surface design can be applied. Objects formed with teeth, points, grooves and other complex surfaces cannot be cleaned to a sufficient extent, either manually or by machine. In addition, there is a washing of contaminated objects contamination of the wash water. Accordingly, in the case of radioactively contaminated objects, for example, ra-

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Dioactively contaminated wastewater, which leads to considerable disposal problems. On the other hand, there is one made by baking Cleaning limited to temperature-stable objects and also associated with considerable energy consumption.

The object of the present invention is to provide a method and to design a device of the type mentioned in such a way that surface-contaminated objects are effectively, quickly, with reasonable Energy needs and can be cleaned in an environmentally friendly way.

To solve the problem, it is proposed in a method of the type mentioned according to the invention that the objects are blown off in a closed system in at least one blow-off process with at least one gas, that at least partially simultaneously with the blow-off, a cleaning and drying circulation of what is in the system Gas is carried out, that after the at least one blow-off process from the system, the gas is pumped down to a vacuum suitable for glow discharges and that the objects are then exposed to an ion and / or electron bombardment caused by gas discharges for further surface cleaning. Such a method is extremely effective in terms of cleaning success and can be carried out relatively quickly. With the help of the blow-off process that takes place under pressure with one gas or one after the other with several gases, coarser surface components of the object to be cleaned are loosened and diverted in the course of the gas circulation. Since the circulated gas is cleaned and dried here, clean and dry circulating gas is always available for discharging further dissolved constituents.

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In the ionic process, which is then carried out under vacuum conditions and / or electron bombardment of the objects, the remaining surface impurities are detached and at least partially in directed the air chamber. Another blow-off and gas circulation can also be carried out. The procedure can be in the case of objects Any surface design can be used and enables a very gentle, highly effective cleaning treatment. Since it is carried out in a closed system, it is a highly environmentally friendly process because it has been removed from the object Impurities can be collected.

It is preferred in the process according to the invention as a gas To use air and / or argon and / or nitrogen. The use of air is particularly simple as it is when the Items to be cleaned in the system are included here anyway. However, it can be useful for particularly thorough cleaning be to use other gases, such as nitrogen and / or argon, as an alternative to or in addition to air, which react to the various Impurities can act in different ways. In this respect, it can be advantageous to have several blow-off processes with the same or different gases. On the other hand, it can be useful to have several gas discharges with the same or different ones To carry out gases. And finally, several blow-off processes and / or several gas discharges can prove to be advantageous to be carried out with the same or different, cold or hot gases one after the other or alternately with one another. The number and sequence of the blow-off processes and gas discharges used per cleaning process are identical or different gases are subject to the respective operating conditions

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adaptations, in particular the type and degree of contamination.

In any case, it is preferred that the object to be cleaned removed impurities are collected, removed and stored in a controlled manner. This is particularly the case with radioactive ones Impurities of the utmost importance. In a further embodiment of the method, the gas pumped out of the cleaning vessel is preferably collected, cleaned and cleaned before it is released dried. Accordingly, there are no environmentally harmful exhaust gas problems.

A device used to carry out the method according to the invention is characterized according to the invention by a device that can be sealed tightly Cleaning container, by means of a blow-off element for blowing off objects located in the cleaning container with at least one gas, through a valve-controlled circulation circuit connected to the cleaning container with a cleaning unit, through a valve-controlled with the cleaning container connectable vacuum pump and connectable by a with the cleaning container and the objects located therein High voltage source off. In view of the highly efficient cleaning process, this device is relatively simple constructed and easy to use. It enables an initial rough cleaning and a subsequent fine cleaning with the The result is that all surface contamination is thoroughly removed, even in surface areas that are difficult to access will. With the device according to the invention, radioactively contaminated objects such as containers and tools, clean in such a way that there are no

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Environmental pollution arise because the contaminants are trapped.

Furthermore, an air chamber which can be connected to the vacuum pump in a valve-controlled manner and has a cleaning unit is preferably valve-controlled circulation circuit provided. This air chamber is used to absorb the fine cleaning process from the Cleaning container of pumped gas with the Contaminants released by gas discharge. Because this contaminated gas is cleaned in the circulation circuit of the air chamber before it is released, no harmful components can escape.

In an expedient embodiment there is a common cleaning unit intended for the circulation circuits of the cleaning container and the air chamber. This multiple use of the cleaning unit leads to a simplification of the device, the function of which is not disturbed by the summary, since the different circulation circuits can be put into operation at different times.

In a further embodiment, the cleaning unit is preferably equipped with a circulating fan, a dust filter and a dryer Mistake. The dust filter is preferably connected upstream of the fan and the dryer is connected downstream. Such a cleaning unit enables dust and moisture to be filtered out of the circulated gas flow. This means that it is in the cleaning container clean circulating gas is always available. If the dust filter is connected upstream of the blower, the blower is treated gently, since this cannot be contaminated. The dryer can contain a moisture binding agent such as a molecular sieve.

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th in order to remove even the smallest moisture particles from the circulated gas flow, such as radioactive contamination could be.

In a practical embodiment, the blow-off element preferably has a compressor sucking in gas from the cleaning container and blow-off arms provided with outlet openings. Of the The high-compression compressor thus removes the gas from the cleaning container in order to reach it under high pressure by means of nozzles cleaning surface to be straightened. The compressor can be arranged inside or outside the cleaning container, wherein the internal arrangement leads to a technical simplification.

In a preferred embodiment, the device has a cleaning container with valve-controlled ventilation and with at least one valve-controlled gas supply line. Through this it is possible to carry out the blow-off as well as circulation and gas discharge processes with different gases, such as with air and nitrogen or argon. Depending on the number of different gases to be used, a corresponding number of gas supply lines can be used to be available. It is possible to introduce gas into the cleaning container or in a cold or hot state heating only in the cleaning container.

In a further embodiment, a valve-controlled exhaust gas pipeline connecting the air chamber to the vacuum pump is preferred and a valve-controlled exhaust port connected to the pump outlet. This measure also enables multiple use the already existing vacuum pump, which initially

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for pumping out the gas or gases with the impurities in the Air chamber and then used to pump the cleaned gas or gases out of the air chamber to the outside. This process prevents does not affect the operating sequence and only leads to better utilization of the vacuum pump.

Furthermore, there is preferably a control element for the correct timing of the valves, the compressor, the blower and the vacuum pump and the high voltage source. This ensures that the cleaning process runs as quickly as possible, without any operating effort and avoiding operating errors.

According to a particularly preferred embodiment, a polarity reversible High voltage source available. By reversing the polarity, this enables an alternating bombardment of the object and the inner one Areas of the cleaning container with ions and / or electrons. This ensures that the entire cleaning container cleaned with every object to be cleaned after the cleaning process including the blow-off device with the compressor and the blow-off arms. Coarser components that are used in the final Fine cleaning process fall on the bottom of the cleaning container, for example in the next one Cleaning process can be removed from the cleaning container by blowing off and circulating.

The invention enables a highly effective, environmentally friendly surface cleaning of any kind in a relatively simple and quick manner igen, contaminated objects. The cleaning process is very intensive and works even in areas that are otherwise difficult to access

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Surface areas. Pollutants detached from the surface are removed from the gas in the device before it is released will. The device according to the invention makes it possible to replace cleaning processes that were previously carried out manually can and achieve significantly better cleaning results than with previous manual and machine cleaning processes can be achieved.

The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing.

A cleaning container 10 is used to hold one to be cleaned Item G and is closed vacuum-tight by a lid 12 * bar. A ventilation nozzle connected to the cover part 2 has a ventilation valve 14 and a power feed-through 16 in the cover 12 enables isolated electrical connection between an outer terminal 18 and an inner terminal 20 within the Cleaning container 10. While this inner connection 20 can be electrically connected to the object or objects G to be cleaned is, a housing connection 22 is used to electrically connect the cleaning container 10 via a switch S with an electrical Reversible high voltage source 24, which is also connected to the external connection 18.

A compressor is located inside the cleaning container 10 26, which suck in gas from the interior of the cleaning container 10, for example in the direction of the arrow and under large Can conduct pressure in blow-off arms 27, which have unspecified outlet openings through which the pressurized gas to the cleaning surface of the object G can be passed. As shown, the blow-off arms 27 enclose the as freely as possible

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item G suspended or set up in the interior to a large extent, so that it can be cleaned from all sides.

A circulation circuit 28 is on the interior of the cleaning container 10 connected and enables a cleaning as well as drying circulation of what is in the cleaning container 10 Gas during the operation of the compressor 26. The circulation circuit 28 has a top side connected to the cleaning container 10 Pipeline 30 with a slide-like valve 32, furthermore one connected to the cleaning container 10 on the underside Pipeline 34 with a slide-like valve 36 and a cleaning unit 38 connecting the pipelines 30 and 34. The the latter has a fan 40, a dust filter 42 connected upstream of it, and a dryer 44 connected downstream of the fan 40 which preferably contains moisture binders such as molecular sieves. When the valves 32 and 36 are open and the Blower 40 are set in motion with the compressor 26 switched on, the one in the cleaning container 10 and with it Gas mixed with impurities is circulated in the circulation circuit 28 in the direction of the arrow and cleaned and dried in the process. As the pipeline 34 opens into the interior of the same in the lower region of the cleaning container 10, when it is circulated, those that have accumulated on the floor are collected coarse impurities are sucked off in order to be filtered off in the dust filter 42. This is important for the fan to do 40 does not suffer any damage.

A pipeline opens into the bottom of the cleaning container 10 46, in which there is a valve 48 and which leads to a vacuum pump 50 leads. The latter is via a pipe 51, in which a valve 52 is located, with the interior of a wind turbine

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sels 54 connected. If with closed valves 32 and 36 and with the valves 48 and 52 open, the vacuum pump for continuously pumping the gas out of the cleaning container 10 50 is put into operation and a gas discharge is generated between the object G and the cleaning container 10, the sucked out impurities from the vacuum pump 50 in the air chamber 54, so that a leakage of pollutants is not is possible.

The air chamber 54 has a Umwälzkreis 56 with an upper side Pipeline 58 which opens into the air chamber 54 and in which there is a slide-like valve 60, and with one on the underside Pipeline 62 which opens into the air chamber 54 and in which a valve 64 is located. The pipes 58 and 62 of the circulation circuit 56 are connected to the pipelines 30 and 34 of the circulation circuit 28, that is to say connected to the same cleaning unit 38. In this way, the contaminated gas in the air chamber 54 with the valves 60 and 64 open and the valves 32, 36, 52, 68 circulated in the circulation circuit 56 and cleaned and dried by means of the dust filter 42 and the dryer 44.

An exhaust pipe connected to the interior of the air vessel 54 66, in which a valve 68 is located, is connected to the pipeline 46 and thus to the vacuum pump 50 in the present case. The latter also has an exhaust port 70 with a valve 72.

After the cleaning and drying of the gas in the air chamber 54, it can be opened with the valves 68 as well as 72 and closed valves 48 and 52 can be safely derived.

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In the present case, the cleaning container 10 is also provided with two valve-controlled gas supply lines 74, 76, by means of whose cold or hot gases, such as argon and / or nitrogen, which are optionally desired for the cleaning processes, in addition to air, can be fed.

The mode of operation of the device shown is as follows: First of all, apart from the ventilation valve 14, all other valves are in place closed. The lid 12 of the cleaning container 10 is removed, and the object to be cleaned G is in the Cleaning container 10 set up electrically insulated between the blow-off arms 27 or suspended. Item G is also electrically connected to the inner connection 20, and the cover 12 is placed on the cleaning container 10 in a gas-tight manner. The ventilation valve 14 is then closed. Thereafter, when air is to be used as the gas, the compressor 26 in Operation set, whereby the object G with surface cleaning Compressed air is treated. During the operation of the compressor 26, the circulation circuit 28 is also opened by opening the valves 32 and 36 and set in motion by switching on the fan 40. During this first surface cleaning, the Surface components detached from compressed air, e.g. B. dust and moisture, filtered in the circulation circuit 2 8 and bound. the Cleaning unit 38 ensures that clean and dry circulating air is always available. After completing this first During the cleaning process, the valves 32 and 36 are closed and the compressor 26 and the fan 40 are switched off. The Abb_as- and circulation processes can be carried out with the aid of the gas supply lines 74, 76 can also be carried out several times with different gases. For this purpose, the cleaning container can be

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nis 10 located gas can be pumped out before the supply of the new gas into the air chamber 54.

For the second cleaning process, the valves 48 and are opened and the vacuum pump 50 is switched on. Inside the cleaning container A vacuum suitable for glow discharges is thereby produced and maintained. After correct Polarity of the high voltage source 24 and after closing the switch S is between the object G and the cleaning container 10 ignited and maintained a gas discharge, by means of which, with correct polarity, an ion and / or electron bombardment of the Surface of the object G takes place. In the process, surface impurities that are actually difficult to access are also found in surface areas replaced. The vacuum pump 50 continuously conveys the contaminated gas from the cleaning container into the air chamber 54, which is under vacuum or under reduced pressure from the previous cleaning process, in which the accumulate detached impurities. In order to achieve an optimal cleaning process not only of the object G, but also to achieve the cleaning container 10 and the parts located therein, it is expedient to use the high voltage source 24 to reverse polarity during the cleaning process, so that too the areas surrounding the object G are bombarded with ions and / or electrons. After completing the cleaning process the valves 48 and 52 are closed, the vacuum pump 50 is switched off, the switch S for the high voltage source 24 opened and the ventilation valve 14 also opened. After removing the cover 13, the then cleaned object G can be removed from the cleaning container 10.

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Not only the blow-off and circulation processes, but also the glow processes the object to be cleaned can be repeated several times, with the same or different ones Gases. You can also choose to have several blow-off or circulation processes and / or several glow processes with or with one gas several gases, which can also be hot, in any number and sequence to achieve the best possible cleaning effect to achieve.

The polluted gas under negative pressure in the air chamber 54 is released after the valves 60 and 64 have been opened and the blower switched on 40 cleaned and dried by means of the cleaning unit 38. Then the valves 60 and 64 are closed, the Valves 68 and 72 open and the vacuum pump 50 switched on. The cleaned gas in the air chamber 54 can thereby be discharged to the outside whereby the initial vacuum in the air chamber 54 is restored. Finally, the valves 68 as well 72 closed and the vacuum pump 50 switched off.

Already during the operation of the circulation circuit 56 and the then taking place discharge of the gas or gases from the air chamber 54 can a further cleaning process of a further object G is prepared by inserting the same into the cleaning container 10 will.

After the circulation circuit 56 has been switched off, it can already be during the discharge of the gas from the air chamber 54, the first cleaning process of the renewed cleaning process can be initiated, wou ch it is possible, the various cleaning processes under mutually overlap for optimal utilization of the device allow.

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Claims (17)

Radium - Chemie AG Teufen Switzerland 294A88Q Method and device for surface cleaning of objects Claims y Process for the surface cleaning of objects, in particular of radioactively contaminated objects, thereby characterized in that the objects in a closed system in at least one AbblasVorgang with at least one Gas are blown off that at least partially simultaneously with the blowing off a cleaning and drying circulation of the gas in the system is carried out that after the at least one blow-off process from the system, the gas is pumped down to a suitable vacuum for glow discharges and that the objects then for further surface cleaning an ion and / or or electron bombardment. 2. The method according to claim 1, characterized in that air and / or argon and / or nitrogen are used as the gas. 3. The method according to claim 1 or 2, characterized in that several blow-off processes can be carried out with the same or different gases. 4. The method according to one or more of claims 1 to 3, characterized in that several gas discharges with the same or different gases. 5. The method according to one or more of claims 1 to 4, characterized in that several blow-off processes and / or mch- 130022/0089 ORIGINAL INSPECTED Several gas discharges with the same or different, cold or hot gases, one after the other or alternating with one another be performed. 6. The method according to one or more of claims 1 to 5, characterized characterized in that the contaminants removed from the object to be cleaned are collected and removed in a controlled manner and be kept. 7. The method according to one or more of claims 1 to 6, characterized characterized in that the evacuated gas is collected, cleaned and dried before releasing. 8. Device for performing the method according to one or more of claims 1 to 3, characterized by a tightly closable cleaning container (10), by means of a blow-off element (26, 27) for blowing off in the cleaning container (10) located objects (G) with at least one gas, through a connected to the cleaning container (10), valve-controlled circulation circuit (28) with a cleaning unit (38), through a valve-controlled with the Cleaning container (10) connectable vacuum pump (50) and by a with the cleaning container (10) and the itself objects (G) therein connectable high voltage source (24). 9. The device according to claim 8, characterized by an air chamber which can be connected in a valve-controlled manner to the vacuum pump (50) (54) with a valve-controlled circulation circuit (56) having a cleaning unit (38). 10. The device according to claim 9, characterized by a ge 130022/0069 Common cleaning unit (38) for the circulation circuits (28, 56) the cleaning container (10) and the air chamber (54). 11. The device according to one or more of claims 8 to 10, characterized by a cleaning unit (38) with a circulating fan (40), a dust filter (42) and a dryer (44). 12. The device according to claim 11, characterized in that the fan (40) is connected upstream of the dust filter (42) and the dryer (44) are connected downstream. 13. The device according to one or more of claims 8 to 12, characterized in that the blow-off element is a gas from the Compressor (26) sucking in cleaning container (10) and blow-off arms (27) provided with outlet openings. 14. The device according to one or more of claims 8 to 13, characterized by a cleaning container (10) with a valve-controlled ventilation and with at least one valve-controlled gas supply line (74, 76). 15. Device according to one or more of claims 8 to 14, characterized by the air chamber (54) with the vacuum pump (50) connecting, valve-controlled exhaust pipe (66) and through a valve-controlled one connected to the pump outlet Exhaust socket (70). 16. The device according to one or more of claims 8 to 15, characterized by a control element for the correct time Controlling the valves, the compressor (26), the fan (40), the vacuum pump (50) and the high voltage source (24). 17. The device according to one or more of claims 8 to 16, characterized by a polarity reversible high voltage source (24). 130022/0069