CN109913936B - Decontamination system and decontamination method - Google Patents
Decontamination system and decontamination method Download PDFInfo
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- CN109913936B CN109913936B CN201910366165.3A CN201910366165A CN109913936B CN 109913936 B CN109913936 B CN 109913936B CN 201910366165 A CN201910366165 A CN 201910366165A CN 109913936 B CN109913936 B CN 109913936B
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Abstract
The invention relates to a decontamination system and a decontamination method. The decontamination system comprises a reaction device and a power supply device. The reaction device comprises a cathode and a liquid absorption assembly, wherein the liquid absorption assembly comprises a liquid absorption piece for absorbing electrolyte, and the liquid absorption piece can be in contact with the cathode and a workpiece to be decontaminated so that the liquid absorption piece can provide the electrolyte for the cathode and the workpiece to be decontaminated. The power supply device is provided with a positive electrode and a negative electrode, wherein the positive electrode can be electrically connected with a workpiece to be decontaminated, and the negative electrode can be electrically connected with the negative electrode. The decontamination system can decontaminate the workpiece to be decontaminated on site, and generates less secondary waste liquid.
Description
Technical Field
The invention relates to the field of decontamination of nuclear facilities, in particular to a decontamination system and a decontamination method.
Background
A common method for decontaminating shallow pollution hot spots of metal parts or structures in nuclear facilities is to disassemble the parts and send the parts to a decontamination workshop, and treat the parts by traditional decontamination means such as traditional hot acid, hot alkali and the like. Alternatively, chemical decontamination solution is used for repeated wiping, washing and decontaminating, but the method can generate more secondary waste liquid.
Disclosure of Invention
Based on this, it is necessary to provide a decontamination system capable of on-site decontamination with less secondary waste liquid.
In addition, a decontamination method is also provided.
A decontamination system, comprising:
the reaction device comprises a cathode and a liquid absorption assembly, wherein the liquid absorption assembly comprises a liquid absorption piece for absorbing electrolyte, and the liquid absorption piece can be in contact with both the cathode and a workpiece to be decontaminated so that the liquid absorption piece can provide the electrolyte for the cathode and the workpiece to be decontaminated; and
and the power supply device is provided with a positive electrode and a negative electrode, the positive electrode can be electrically connected with the workpiece to be decontaminated, and the negative electrode can be electrically connected with the cathode.
In one embodiment, the wicking assembly further comprises a housing configured to receive the wicking member and the housing is configured to at least partially receive the cathode, the portion of the cathode received within the housing being configured to contact the wicking member.
In one embodiment, the material of the liquid absorbing member is selected from one of polyurethane foam, wood cellulose and polyacrylate.
In one embodiment, the decontamination system further includes a vacuum device in communication with the wicking assembly, the vacuum device being capable of drawing a vacuum on the wicking assembly to enable the wicking member to contact both the cathode and the work piece to be decontaminated.
In one embodiment, the cathode is selected from one of a cerium tungsten electrode, a silver tungsten electrode, and a titanium-coated iridium electrode.
In one embodiment, the decontamination system further includes a liquid supply device capable of holding the electrolyte, the liquid supply device capable of communicating with the wicking assembly such that the electrolyte in the liquid supply device can flow into the wicking assembly and back from the wicking assembly to the liquid supply device.
In one embodiment, the liquid supply device includes a liquid supply tank, a liquid supply pump, and a liquid return pump, the liquid supply tank can contain the electrolyte, the liquid supply pump can make the electrolyte in the liquid supply tank flow into the liquid suction assembly, and the liquid return pump can make the electrolyte flowing out of the liquid suction assembly flow into the liquid supply tank.
In one embodiment, the decontamination system further includes a reaction cell, the reaction cell can contain electrolyte, the cell wall of the reaction cell can be electrically connected with the negative electrode, the reaction cell can accommodate the workpiece to be decontaminated and the cathode, when the cell wall of the reaction cell is electrically connected with the negative electrode, the cathode is disconnected from the negative electrode, and when the cathode is electrically connected with the negative electrode, the cell wall of the reaction cell is disconnected from the negative electrode.
A method of decontamination comprising the steps of:
contacting a liquid absorbing member with the cathode and the workpiece to be decontaminated, the liquid absorbing member absorbing an electrolyte; and
and electrifying the cathode and the workpiece to be decontaminated, wherein the cathode is electrically connected with the negative electrode, and the workpiece to be decontaminated is electrically connected with the positive electrode.
In one embodiment, in the step of electrifying the cathode and the workpiece to be decontaminated, the current density is 2A/cm2～20A/cm2。
In one embodiment, in the step of electrifying the cathode and the workpiece to be decontaminated, the temperature of the electrolyte is 30-90 ℃.
In one embodiment, in the step of contacting the liquid absorbing member with the cathode and the workpiece to be decontaminated, the distance between the cathode and the workpiece to be decontaminated is 1 cm-5 cm.
The decontamination system adopts an electrolytic decontamination technology, the liquid absorbing part can be contacted with the cathode and the workpiece to be decontaminated, the workpiece to be decontaminated can be connected with the anode of the power supply device, the cathode can be connected with the cathode of the power supply device, when the liquid absorbing part absorbs electrolyte, the liquid absorbing part is contacted with the cathode and the workpiece to be decontaminated respectively, so that the electrolyte is contacted with the workpiece to be decontaminated and the cathode respectively to form a loop, the workpiece to be decontaminated is decontaminated on site, and the decontamination can be carried out without disassembling the workpiece to be decontaminated. And because the liquid absorbing piece is contacted with the cathode and the workpiece to be decontaminated, the lower electrolyte flow can be adopted, namely, the electrolyte can be contacted with the cathode and the workpiece to be decontaminated to form a loop, so that less secondary waste liquid is generated by the decontamination system. Therefore, the decontamination system can decontaminate the workpiece to be decontaminated on site, and generates less secondary waste liquid.
Drawings
FIG. 1 is a schematic diagram of the construction of an embodiment of a decontamination system;
FIG. 2 is a schematic diagram of the reaction apparatus in the decontamination system of FIG. 1;
FIG. 3 is a process flow diagram of an embodiment of a decontamination method.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the following description taken in conjunction with the accompanying drawings. The detailed description sets forth the preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1, one embodiment of a decontamination system 10 includes: a reaction apparatus 100 and a power supply apparatus 200.
Referring to fig. 2, the reaction apparatus 100 includes a cathode 110 and a liquid-absorbing assembly 120, the liquid-absorbing assembly 120 includes a liquid-absorbing member 122 for absorbing electrolyte, and the liquid-absorbing member 122 can contact with both the cathode 110 and the workpiece 20 to be decontaminated.
Specifically, the cathode 110 is selected from one of a cerium tungsten electrode, a silver tungsten electrode, and a titanium-plated iridium electrode. The shape of the cathode 110 and the liquid absorbing member 122 is selected from one or more of a circular plate shape, a triangular shape, a square shape, a net shape and a conductive clip. The cathode 110 and the liquid absorbing member 122 are set to have different shapes so as to be consistent with the shapes of the polluted hot spots of the workpiece 20 to be decontaminated, so that the workpiece 20 to be decontaminated, the liquid absorbing member 122 and the cathode 110 are all in close contact, and the decontamination of the hot spots is facilitated. The shape of the cathode 110 and the liquid absorbing material 122 can be applied to a work 20 waiting for decontamination, which is a plane, a small plane (angle steel), or a curved surface (tank).
The thickness of the cathode 110 is 2mm to 10 mm. The area of the cathode 110 is 40cm2～200cm2. The upper limit of the area of the cathode was set to 200cm2Because of the larger areaA larger direct-current power supply is needed, the power supply can be set to the value, and the cost is reduced; the lower limit is set to 40cm2In order to ensure decontamination efficiency. The thickness is set to the above value because machining cost of the cathode 110 of the thickness is the lowest and electrode life is satisfactory. And the above values can ensure that the decontamination effect reaches the expected target.
One of the difficult problems of electrochemical decontamination technology engineering is the problem of cathode material life, and the common cathode has the contradiction of difficult reconciliation in the aspects of conductivity, life, edge discharge, acid corrosion resistance and the like. The cathode solves the problems of short service life, serious edge discharge, poor conductivity, high heat generation and the like of the common cathode.
Specifically, the material of the liquid absorbing member 122 is selected from one of polyurethane foam, wood cellulose and polyacrylate. By adopting the materials, the liquid absorbing piece 122 can absorb lower electrolyte flow, namely, the workpiece 20 to be decontaminated and the cathode 110 can be in contact with the electrolyte, and the using amount of the electrolyte is reduced. And the liquid absorbing piece 122 is contacted with the cathode 110 and the workpiece 20 to be decontaminated, so that the using amount of the electrolyte can be reduced, and the generated secondary waste liquid can be reduced.
Specifically, the electrolyte includes a detergent, a conductivity promoter, a stabilizer, a pH buffer, and water. Wherein the detergent is nitric acid or phosphoric acid. The conductive accelerant is sodium nitrate or sodium phosphate. The stabilizer is one selected from citric acid and acetic acid. The pH buffer is sodium citrate or hydroxylamine hydrochloride.
The wicking assembly 120 also includes a housing 124. The housing 124 can house the wicking member 122. The material of the liquid absorbing member 122 is a water-swellable material, and when the liquid absorbing member 122 is accommodated in the outer shell 124 and electrolyte flows through the outer shell 124, the liquid absorbing member 122 absorbs water and swells, so that the liquid absorbing member 122 is in contact with the outer shell 124, and the liquid absorbing member 122 cannot fall off from the outer shell 124 in the using process. The housing 124 can also at least partially house the cathode 110. The portion of the cathode 110 received within the housing 124 can be in contact with the wicking member 122. The shell 124 can provide a place for the contact of the liquid absorbing piece 122, the cathode 110 and the workpiece 20 to be decontaminated and the electrolytic decontamination, and bear the electrolyte in the decontamination process, so that the electrolyte does not leak.
The power supply device 200 has a positive electrode capable of being electrically connected to the workpiece 20 to be decontaminated and a negative electrode capable of being electrically connected to the cathode 110. Specifically, in the present embodiment, the power supply device 200 includes an electrolysis power source 210 and a power supply line 220. The electrolysis power source 210 has a positive electrode and a negative electrode. The electrolytic power source 210 can be capable of passing through the power line 220 such that the positive electrode can be electrically connected to the workpiece 20 to be decontaminated and the negative electrode can be electrically connected to the cathode 110. It is understood that in other embodiments, the power supply device 200 may be other devices, and any power supply device having a positive electrode and a negative electrode may be used as the power supply device 200 in this embodiment.
The power supply device 200 can regulate and control parameters such as input voltage, input current, output current, and output voltage. Specifically, the output current of the power supply device 200 is 200A to 400A, the output voltage is 5V to 100V, the input current is 40A, and the input voltage is 380V. The power supply device 200 using the output current and the output voltage as the above values functions as: the electrolysis equipment is provided with direct current and a given voltage.
The decontamination system 10 also includes a vacuum apparatus 300, the vacuum apparatus 300 being capable of communicating with the wicking assembly 120, and the vacuum apparatus 300 being capable of drawing a vacuum on the wicking assembly 120 to enable the wicking member 122 to contact both the cathode 110 and the workpiece 20 to be decontaminated. Specifically, the vacuum apparatus 300 is capable of evacuating the housing 124 of the wicking assembly 120.
In the present embodiment, the vacuum apparatus 300 includes a vacuum pump 310 and a vacuum duct 320. Vacuum pump 310 can be in communication with housing 124 of wicking assembly 120 via vacuum conduit 320. The vacuum apparatus 300, on the one hand, can secure the wicking assembly 120 to the surface of the workpiece 20 to be decontaminated, avoiding the labor intensity associated with manual securing. On the other hand, the vacuum apparatus 300 can also hermetically connect the liquid absorbing member 122 with the workpiece 20 to be decontaminated, and the liquid absorbing member 122 with the cathode 110, so as to avoid liquid leakage.
The decontamination system 10 also includes a liquid supply device 400, wherein the liquid supply device 400 can contain electrolyte, and the liquid supply device 400 can be in communication with the liquid suction assembly 120, such that the electrolyte in the liquid supply device 400 can flow into the liquid suction assembly 120, and the electrolyte can flow back to the liquid supply device 400 from the liquid suction assembly 120. The electrolyte can continuously flow in the liquid suction assembly 120 by using the liquid supply device 400, so that the breakdown effect caused by overhigh local metal ion concentration is avoided. Specifically, the liquid supply apparatus 400 can be in communication with the housing 124 of the wicking assembly 120.
Specifically, the liquid supply device 400 includes a liquid supply tank 410, a liquid supply pump 420, and a liquid return pump 430. Feed tank 410 can hold electrolyte, and feed pump 420 can flow the electrolyte in feed tank 410 into pipetting assembly 120. Return pump 430 is capable of flowing electrolyte from wicking assembly 120 into feed reservoir 410. Fluid supply pump 420 is also capable of regulating the flow of electrolyte into pipetting assembly 120.
Further, the liquid supply apparatus 400 further includes a first conduit 440 and a second conduit 450. Fluid supply tank 410 can communicate with housing 124 of wicking assembly 120 through first conduit 440 and second conduit 450. The liquid supply pump 420 is provided on the first pipe 440, and the liquid return pump 430 is provided on the second pipe 450. The electrolyte in the supply tank 410 can flow into the housing 124 of the pipetting assembly 120 through the first pipe 440 and the supply pump 420, and the electrolyte in the housing 124 can flow into the supply tank 410 through the second pipe 450 and the return pump 430.
Further, the liquid supply device 400 further comprises a heating unit for heating the electrolyte to 30-90 ℃. The heating unit is connected to the liquid supply tank 410. The heating unit is arranged to heat the electrolyte, so that the electrolysis speed of the electrolyte is improved, and the decontamination effect is improved.
In this embodiment, the liquid supply apparatus 400 further includes a fluid return collection tank 460. the fluid return collection tank 460 can be in communication with the housing 124 of the wicking assembly 120 to collect the contaminated fluid within the wicking assembly 120. the contaminated fluid is an electrolyte waste fluid that does not meet the electrolysis requirements6bq/g, pH greater than 4. Return collection tank 460 can also be coupled to feed tank 410 to collect the contaminated liquid within feed tank 410.
When the liquid supply device 400 of the decontamination system 10 includes a return liquid collection tank 460, the vacuum pump 310 is also in communication with the return liquid collection tank 460 via the vacuum conduit 320 to collect the contaminated liquid in the wicking assembly 120. By means of the suction of the vacuum device 300, the polluted liquid in the liquid suction assembly 120 can be completely sucked into the liquid return collecting tank 460, and the subsequent electrolytic decontamination is prevented from being affected.
In use of the liquid supply apparatus 400, the electrolyte in the liquid supply tank 410 flows into the housing 124 of the liquid absorbing assembly 120 through the first pipe 440 and the liquid supply pump 420, and the electrolyte in the housing 124 flows into the liquid supply tank 410 through the second pipe 450 and the liquid return pump 430. When the electrolyte can not meet the electrolysis requirement, obtaining the polluted liquid, and collecting the polluted liquid in the liquid returning collecting tank 460.
In some embodiments, the decontamination system 10 further includes a reaction cell 500, the reaction cell 500 being capable of holding an electrolyte, and a cell wall of the reaction cell 500 being capable of electrically connecting to the negative electrode, the reaction cell 500 being capable of receiving the workpiece 20 to be decontaminated and the cathode 110. When the cell wall of the reaction cell 500 is electrically connected to the negative electrode, the cathode 110 is disconnected from the negative electrode. When the cathode 110 is electrically connected to the negative electrode, the cell wall of the reaction cell 500 is electrically connected to the negative electrode. The reaction tank 500 can be used as a place for decontaminating the small workpiece 20 to be decontaminated, and is used for decontaminating the small workpiece 20 to be decontaminated.
When the reaction cell 500 is used for decontamination of a small-sized workpiece 20 to be decontaminated, the positive electrode of the electrolytic power supply 210 is electrically connected to the workpiece 20 to be decontaminated, the negative electrode is electrically connected to the cathode 110 housed in the reaction cell 500, or the negative electrode is electrically connected to the cell wall of the reaction cell 500. At this time, the liquid absorbing member 122 is not in contact with the cathode 110 and the workpiece 20 to be decontaminated. The cell wall of the reaction cell 500 is generally made of stainless steel material, and can be directly used as a cathode to be electrically connected with the negative electrode of the electrolysis power supply 210, and at this time, the cell wall of the reaction cell 500 is electrolyzed, which affects the service life of the reaction cell 500. Therefore, in some embodiments, the cathode 110 may be further contained in the reaction cell 500, so that the cathode 110 can be electrically connected to the negative electrode to perform the electrolytic reaction.
The reaction cell 500 can also communicate with the liquid supply device 400 to supply the liquid supply device 400 with the electrolyte. Specifically, the reaction tank 500 can communicate with the liquid supply tank 410 of the liquid supply device 400. When the reaction tank 500 is communicated with the liquid supply device 400, the reaction tank 500 can be used as a preparation tank and a storage tank for the electrolyte, and is used for preparing and discharging the electrolyte so as to convey the electrolyte to the liquid supply device 400. The reaction tank 500 is used as a backup multipurpose component, so that the utilization rate of the reaction tank 500 is improved, the application range of the decontamination system 10 is expanded, and the use convenience is improved.
In some embodiments, the decontamination system 10 further includes a waste liquid device 600, the waste liquid device 600 being capable of communicating with the liquid supply device 400 to receive the contaminated liquid generated by the liquid supply device 400. Specifically, the waste liquid device 600 can be in communication with the liquid return collection tank 460 of the liquid supply device 400. Further, the waste liquid device 600 can also communicate with the reaction tank 500 to receive the polluted liquid generated in the reaction tank 500. When the reaction tank 500 is used as a decontamination site for the small-sized work 20 to be decontaminated, the generated contaminated liquid can flow into the waste liquid device 600. The waste liquid device 600 is used for storing the polluted liquid, so that the subsequent polluted liquid is conveniently discharged. It will be appreciated that in other embodiments, the waste device 600 may be omitted and the contaminated liquid stored in the return liquid collection tank 460.
Further, the decontamination system 10 may further include a control device (not shown). The control device may be electrically connected to the reaction device 100, the power supply device 200, the vacuum device 300, and the liquid supply device 400, respectively. The control device can collectively control the reaction device 100, the power supply device 200, the vacuum device 300, and the liquid supply device 400 of the decontamination system 10. Specifically, the centralized control includes process parameter control, monitoring of instruments, and process control. Further, the process parameter control includes control and real-time display of current density (current), electrolyte flow, and the like. The monitoring of the meter includes: monitoring and controlling vacuum degree, voltage, liquid level, etc. The control of the process comprises: can control the opening and closing of the devices such as valves, pumps and the like.
Through setting up controlling means, can carry out centralized control to technological parameter, instrument state etc. in the decontamination reaction, through operating controlling means, can realize the adjustment to the parameter for each parameter in the decontamination reaction is clear, and can monitor the parameter conveniently, has avoided directly contacting reaction unit 100, liquid supply device 400 etc..
Further, the decontamination system 10 may also include a cart (not shown). The cart can carry the reaction apparatus 100, the power supply apparatus 200, the vacuum apparatus 300, the liquid supply apparatus 400, the reaction tank 500, the waste liquid apparatus 600, the control apparatus, and the like. Specifically, the lower part of the cart is provided with casters. The upper part of the cart is provided with a handle for pushing the cart. The cart can conveniently move the decontamination system 10 to decontaminate the workpieces 20 to be decontaminated in situ at different locations.
The electrolytic decontamination technology is characterized in that a workpiece to be decontaminated is connected to the anode of an electrolytic power supply and the cathode of the electrolytic power supply by utilizing the principle of electrochemical oxidation, and a current loop is formed under the action of electrolyte. Under the action of an electric field, metal elements on the surface of the workpiece to be decontaminated are oxidized into cations and dissolved in the electrolyte, and meanwhile, radioactive pollutants attached to the surface of the workpiece to be decontaminated are also dissolved in the electrolyte, so that the purpose of decontamination is achieved.
The decontamination system 10 described above has at least the following advantages:
(1) the decontamination system 10 can not only decontaminate large-sized workpieces 20 to be decontaminated on site by using the liquid suction assembly 120 and the cathode 110, but also decontaminate small-sized workpieces 20 to be decontaminated by using the reaction tank 500, so that decontamination of different types of workpieces 20 to be decontaminated is realized, and the utilization rate of the decontamination system 10 is improved.
(2) The decontamination system 10 has high decontamination rate and controllable decontamination depth, and can realize the decontamination depth of more than 10 microns in 3 minutes for the workpiece 20 to be decontaminated, thereby achieving the purpose of deep decontamination, cleaning and control.
(3) The decontamination system 10 can decontaminate the workpiece 20 to be decontaminated by electrolysis, and realize recycling of the workpiece 20 to be decontaminated or cleaning and control of the workpiece 20 to be decontaminated.
(4) The decontamination system 10 is configured to contact the liquid absorbing member 122 with both the cathode 110 and the workpiece 20 to be decontaminated, so that the cathode and the workpiece 20 to be decontaminated can be contacted with the electrolyte with less electrolyte, thereby performing an electrolytic reaction. And the combination of the liquid supply device 400 enables the electrolyte to be recycled, thereby reducing the discharge of secondary waste liquid.
Referring to fig. 3, one embodiment of a decontamination method includes the steps of:
step S210: and enabling the liquid absorbing piece to contact the cathode and the workpiece to be decontaminated, wherein the liquid absorbing piece absorbs the electrolyte.
Wherein, the material of imbibition piece is selected from one of polyurethane foaming glue, wood cellulose and polyacrylate.
The cathode is selected from one of a cerium tungsten electrode, a silver tungsten electrode and a titanium iridium-plated electrode.
The electrolyte comprises a detergent, a conductivity promoter, a stabilizer, a pH buffer and water. Wherein the detergent is nitric acid or phosphoric acid. The conductive accelerant is sodium nitrate or sodium phosphate. The stabilizer is one selected from citric acid and acetic acid. The pH buffer is sodium citrate or hydroxylamine hydrochloride.
The step of contacting the liquid absorbent member with the cathode and the work piece to be decontaminated comprises:
providing a housing capable of accommodating the liquid absorbing member and also capable of at least partially accommodating the cathode, the portion of the cathode accommodated in the housing being capable of contacting the liquid absorbing member;
and connecting the shell with the liquid absorbing piece, and vacuumizing the shell by using a vacuum device so that the liquid absorbing piece is contacted with the cathode and the workpiece to be decontaminated.
In step S210, the distance between the cathode and the workpiece to be decontaminated is 1 cm-5 cm. The effect of setting the pitch to the above values is: according to the optimum pole spacing determined by experiments, the electrolytic resistance is reduced as much as possible, and meanwhile, the short circuit caused by mutual contact is avoided.
Step S220: and electrifying the cathode and the workpiece to be decontaminated, wherein the cathode is electrically connected with the cathode, and the workpiece to be decontaminated is electrically connected with the anode.
Specifically, in the step of electrifying the cathode and the workpiece to be decontaminated, the current density is 2A/cm2～20A/cm2. Setting the current density to the above values has the effect of: the current density can obtain the best electrolytic decontamination effect.
In the step of electrifying the cathode and the workpiece to be decontaminated, the temperature of the electrolyte is 30-90 ℃. The temperature of the electrolyte is set to be 30-90 ℃, so that the electrolysis rate of the electrolyte can be improved, and the decontamination effect is improved.
In the process of electrifying the cathode and the workpiece to be decontaminated, the method also comprises the following steps: with flow of electrolyteThe amount is 0.01L/h.cm2～0.05L/h.cm2And continuously introducing the electrolyte into the liquid absorbing piece. The effect of setting the electrolyte flow rate to the above value is: maintaining a stable electrolyte flow in the wicking member.
In step S220, parameters such as current density, electrolyte temperature, and electrolyte flow during the energization process are controlled by the control device.
The decontamination method has at least the following advantages:
(1) the decontamination method can carry out on-site rapid decontamination on the workpiece to be decontaminated by utilizing the contact of the liquid absorption piece with the cathode and the workpiece to be decontaminated.
(2) The decontamination method can control the decontamination depth of the workpiece to be decontaminated by adjusting the process parameters of decontamination reaction and the components of the electrolyte.
(3) The decontamination method can reduce the generation of secondary waste liquid.
The following are specific examples:
example 1
The decontamination system of this example was used to decontaminate the inner walls of a stainless steel sump. An LB124 type surface pollution measuring instrument is adopted to measure the initial pollution level, and the pollution is mainly beta pollution. The decontamination process is as follows:
(1) placing the absorbent member within the housing to obtain the absorbent assembly. And (3) contacting the liquid absorbing part with the cathode and the area (1) of the inner wall of the stainless steel storage tank, and vacuumizing the liquid absorbing component by a vacuum device to ensure that the liquid absorbing part is in close contact with the cathode and the inner wall of the stainless steel storage tank. Wherein the liquid absorbing piece is made of polyurethane foaming glue. The cathode adopts a disc-shaped cerium-tungsten electrode and has an area of 50cm2And the distance between the cathode and the inner wall of the stainless steel storage tank is 1 cm.
(2) The positive electrode of an electrolytic power supply is electrically connected with the area 1 of the inner wall of the stainless steel storage tank, the negative electrode of the electrolytic power supply is electrically connected with the cathode, electrolyte in a liquid supply tank flows into the shell of the liquid suction assembly by a liquid supply pump of the liquid supply device, the electrolyte in the shell flows back to the liquid supply tank by a liquid return pump, the electrolytic power supply is started, and the cathode and the area 1 are electrified. Wherein, the electrolyte adopts a nitric acid system. Calculated by mass percentage, in the electrolyte55% of nitric acid (the concentration of the nitric acid is 65%), 10% of conductive promoter sodium nitrate, 5% of stabilizing agent citric acid, 4% of pH buffering agent and 26% of distilled water. In the step of the electrification treatment, the current density is 5A/cm2The temperature of the electrolyte is 30 ℃, and the flow rate of the electrolyte is 0.01L/h.cm2。
(3) Repeating the steps (1) and (2), and electrically connecting the positive electrode of the electrolytic power supply with the region 2, the region 3 and the region 4 of the inner wall of the stainless steel storage tank respectively to perform the electrifying treatment. Where the initial contamination levels of zone 1, zone 2, zone 3, and zone 4 are close. The soil removal times for the different zones are shown in table 1 below.
Results of the contamination levels before and after the decontamination of the area 1, the area 2, the area 3, and the area 4 are shown in table 1 below, in which the contamination level before the decontamination and the contamination level after the decontamination were measured by an LB124 type surface contamination measuring instrument, and the corrosion depth was measured by a weight loss method with a decontamination factor DF being the contamination level before the decontamination/the contamination level after the decontamination. Specifically, the mass of the workpiece to be decontaminated is weighed by a one-ten-thousandth balance before and after corrosion, and the corrosion depth is calculated by dividing the mass loss before and after corrosion by the corrosion area.
TABLE 1 comparison of stain levels before and after decontamination and decontamination results
Example 2
The decontamination system of this example was used to decontaminate the outer walls of a heavily contaminated stainless steel sump. An LB124 type surface pollution measuring instrument is adopted to measure the initial pollution level, and the pollution is mainly beta pollution. The decontamination process is as follows:
(1) placing the absorbent member within the housing to obtain the absorbent assembly. And (3) contacting the liquid absorbing part with the cathode and the area (1) on the outer wall of the stainless steel storage tank, and vacuumizing the liquid absorbing component by using a vacuum device to ensure that the liquid absorbing part is in close contact with the cathode and the outer wall of the stainless steel storage tank. Wherein the liquid absorbing component is made of wood cellulose. The cathode adopts a mesh titanium iridium-plated electrode, and the area of the cathode is 50cm2Between the cathode and the outer wall of the stainless steel tankThe distance is 5 cm.
(2) The positive electrode of an electrolytic power supply is electrically connected with the area 1 on the outer wall of the stainless steel storage tank, the negative electrode of the electrolytic power supply is electrically connected with the cathode, electrolyte in a liquid supply tank flows into the shell of the liquid suction assembly by a liquid supply pump of the liquid supply device, the electrolyte in the shell flows back to the liquid supply tank by a liquid return pump, the electrolytic power supply is started, and the cathode and the area 1 are electrified. Wherein, the electrolyte adopts a phosphoric acid system. According to the mass percentage, the phosphoric acid is 15 percent (the concentration of the phosphoric acid is 85 percent), the conductivity promoter sodium phosphate is 10 percent, the stabilizing agent acetic acid is 5 percent, the pH buffering agent is 8 percent, and the distilled water is 62 percent. In decontamination reaction, the current density is 20A/cm2The flow rate of the electrolyte is 0.05L/h.cm2。
(3) Repeating the steps (1) and (2), and electrically connecting the positive electrode of the electrolytic power supply with the region 2, the region 3 and the region 4 of the outer wall of the stainless steel storage tank respectively to perform the electrifying treatment. Where the initial contamination levels of zone 1, zone 2, zone 3, and zone 4 are close. The soil removal times for the different zones are shown in table 2 below.
The results of the contamination levels before and after decontamination of zone 1, zone 2, zone 3 and zone 4 are shown in table 2 below, and the test methods are the same as those in example 1:
TABLE 2 comparison of stain levels before and after decontamination and decontamination results
Example 3
The decontamination system of the embodiment is used for decontaminating a stainless steel cover plate with heavy pollution. An LB124 type surface pollution measuring instrument is adopted to measure the initial pollution level, and the pollution is mainly beta pollution. The decontamination process is as follows:
(1) placing the absorbent member within the housing to obtain the absorbent assembly. And (3) contacting the liquid absorbing piece with the cathode and the area 1 of the stainless steel cover plate of the workpiece to be decontaminated, and vacuumizing the liquid absorbing assembly through a vacuum device to ensure that the liquid absorbing piece is in close contact with the cathode and the inner surface of the workpiece to be decontaminated. Wherein, the material of the liquid absorbing component is polyacrylate. The cathode adopts a reticular silver-tungsten electrode, and the cathode surfaceThe product is 200cm2And the distance between the cathode and the stainless steel cover plate of the workpiece to be decontaminated is 3 cm.
(2) The positive electrode of an electrolytic power supply is electrically connected with the area 1 of the stainless steel cover plate of the workpiece to be decontaminated, the negative electrode of the electrolytic power supply is electrically connected with the negative electrode, electrolyte in a liquid supply tank flows into the shell of the liquid suction assembly by a liquid supply pump of the liquid supply device, the electrolyte in the shell flows back to the liquid supply tank by a liquid return pump, the electrolytic power supply is started, and the negative electrode and the area 1 are electrified. Wherein, the electrolyte adopts a nitric acid system. According to the mass percentage, the nitric acid is 55 percent (the concentration of the nitric acid is 65 percent), the conductive promoter sodium nitrate is 10 percent, the stabilizing agent citric acid is 5 percent, the pH buffering agent is 4 percent, and the distilled water is 26 percent. In decontamination reaction, the current density is 2A/cm2The flow rate of the electrolyte is 0.03L/h.cm2。
(3) And (3) repeating the step (1) and the step (2), and electrically connecting the anode of the electrolytic power supply with the area 2, the area 3 and the area 4 of the stainless steel cover plate of the workpiece to be decontaminated respectively to perform electrifying treatment. Where the initial contamination levels of zone 1, zone 2, zone 3, and zone 4 are close. The soil removal times for the different zones are shown in table 3 below.
The results of the stain levels before and after decontamination of zone 1, zone 2, zone 3 and zone 4 are shown in table 3 below, the test methods being the same as those in example 1:
TABLE 3 comparison of stain levels before and after decontamination and decontamination results
Example 4
The decontamination system of this embodiment is used to decontaminate a small stainless steel tray that is heavily contaminated. An LB124 type surface contamination measuring instrument is adopted to measure the initial contamination level, and the contamination is mainly alpha contamination. The decontamination process is as follows:
(1) electrically connecting the positive electrode of an electrolytic power supply with a small stainless steel tray of a workpiece to be decontaminated, connecting the negative electrode of the electrolytic power supply with a cathode, containing electrolyte in a reaction tank, placing the workpiece to be decontaminated and the cathode in the reaction tank, turning on the electrolytic power supply, and aligning the cathode and the small stainless steel tray of the workpiece to be decontaminatedAnd carrying out electrolytic treatment. Wherein, the electrolyte adopts a phosphoric acid system. According to the mass percentage, the phosphoric acid is 15 percent (the concentration of the phosphoric acid is 85 percent), the conductivity promoter sodium phosphate is 10 percent, the stabilizing agent acetic acid is 5 percent, the pH buffering agent is 8 percent, and the distilled water is 62 percent. In decontamination reaction, the current density is 10A/cm2The flow rate of the electrolyte is 0.01L/h.cm2. The cathode adopts a silver-tungsten electrode, and the area of the cathode is 100cm2And the distance between the cathode in the reaction tank and the stainless steel small tray is 4 cm.
(2) And after decontamination is finished, recycling the polluted liquid in the reaction tank to a waste liquid device.
The results of the contamination levels before and after the decontamination of the stainless steel small pallet of the workpiece to be decontaminated are shown in table 4 below, and the test methods are the same as those in example 1:
TABLE 4 stain levels before and after decontamination and decontamination results
Note: the area of the stainless steel small tray is small, and the measurement is only performed once by an LB124 type instrument.
Comparative example 1
The decontamination process of comparative example 1 differs from the decontamination process of example 1 in that: the material of the liquid-absorbent member in comparative example 1 was glass fiber cotton.
The results of the contamination levels before and after decontamination of zone 1, zone 2, zone 3 and zone 4 are shown in table 5 below, and the test methods are the same as those in example 1:
TABLE 5 comparison of stain levels before and after decontamination and decontamination results
As can be seen from the comparison between comparative example 1 and example 1, the polyurethane foam in example 1 is used as the material of the liquid absorbing member, and the decontamination effect is better under the same conditions than the material of the liquid absorbing member in comparative example 1.
Comparative example 2
The decontamination process of comparative example 2 differs from the decontamination process of example 1 in that: the cathode in comparative example 2 was a copper electrode.
The contamination levels before and after decontamination of the area 1, the area 2, the area 3 and the area 4 were measured, and the measurement method was the same as that in the example 1.
Tests show that the decontamination effect in comparative example 2 is not obviously reduced compared with that in example 1, but the cathode electrode plate is seriously corroded and consumed by itself in the decontamination process, and the service life of the cathode electrode plate cannot meet the use requirement. Meanwhile, the components of the electrolyte are obviously changed, so that the electrolyte is prematurely lost, and the actual utilization of electrolytic decontamination is not facilitated.
The above experimental results all show that the decontamination systems in examples 1-4 can decontaminate the workpiece to be decontaminated on site. And the decontamination depth and the decontamination level of the workpiece to be decontaminated can be flexibly controlled by controlling the process parameters, the electrolyte components and the like in the decontamination method.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A decontamination system, comprising:
the reaction device comprises a cathode and a liquid absorption assembly, wherein the liquid absorption assembly comprises a liquid absorption piece for absorbing electrolyte, and the liquid absorption piece can be in contact with both the cathode and a workpiece to be decontaminated so that the liquid absorption piece can provide the electrolyte for the cathode and the workpiece to be decontaminated; and
the power supply device is provided with a positive electrode and a negative electrode, the positive electrode can be electrically connected with the workpiece to be decontaminated, and the negative electrode can be electrically connected with the cathode;
the liquid absorbing part is made of a water-swellable material, the cathode is selected from one of a cerium-tungsten electrode, a silver-tungsten electrode and a titanium-plated iridium electrode, the surface of a workpiece to be decontaminated contains radioactive pollutants, the liquid absorbing part is made of one of polyurethane foam rubber, wood cellulose and polyacrylate, the thickness of the cathode is 2-10 mm, and the area of the cathode is 40cm2～200cm2The decontamination system also includes a vacuum device in communication with the wicking assembly, the vacuum device capable of drawing a vacuum on the wicking assembly to enable the wicking member to contact both the cathode and the work piece to be decontaminated.
2. The decontamination system of claim 1, wherein the wicking assembly further comprises a housing configured to receive the wicking member and the housing is configured to at least partially receive the cathode, the portion of the cathode received within the housing being contactable with the wicking member.
3. The decontamination system of claim 1, wherein the liquid absorbent member is a polyurethane foam.
4. The decontamination system of claim 1, wherein the vacuum device comprises a vacuum pump and a vacuum conduit, the vacuum pump being capable of communicating with the wicking assembly through the vacuum conduit.
5. The decontamination system of claim 1, further comprising a liquid supply device capable of holding the electrolyte, the liquid supply device capable of communicating with the wicking assembly such that the electrolyte in the liquid supply device can flow into the wicking assembly and back from the wicking assembly to the liquid supply device.
6. The decontamination system of claim 5, wherein the liquid supply device comprises a liquid supply tank capable of holding the electrolyte, a liquid supply pump capable of flowing the electrolyte from the liquid supply tank into the liquid absorption assembly, and a liquid return pump capable of flowing the electrolyte from the liquid absorption assembly into the liquid supply tank.
7. The decontamination system of claim 1, further comprising a reaction cell capable of holding an electrolyte and having a cell wall capable of electrically connecting to the negative electrode, the reaction cell capable of holding the workpiece to be decontaminated and the cathode, wherein the cell wall of the reaction cell is electrically connected to the negative electrode with the cathode disconnected from the negative electrode and the cell wall of the reaction cell is electrically connected to the negative electrode with the cathode disconnected from the negative electrode.
8. A method of decontamination, comprising the steps of:
enabling a liquid absorbing piece to contact a cathode and a workpiece to be decontaminated, wherein the liquid absorbing piece absorbs electrolyte, the liquid absorbing piece is made of a water swelling material, the cathode is selected from one of a cerium tungsten electrode, a silver tungsten electrode and a titanium iridium-plated electrode, the surface of the workpiece to be decontaminated contains radioactive pollutants, the liquid absorbing piece is made of one of polyurethane foam rubber, wood cellulose and polyacrylate, the thickness of the cathode is 2-10 mm, and the area of the cathode is 40cm2～200cm2(ii) a And
electrifying the cathode and the workpiece to be decontaminated, wherein the cathode is electrically connected with the negative electrode, and the workpiece to be decontaminated is electrically connected with the positive electrode;
wherein the step of contacting the liquid absorbing member with the cathode and the work piece to be decontaminated comprises: providing a housing capable of receiving the liquid absorbent member and also capable of at least partially receiving the cathode, the portion of the cathode received within the housing capable of contacting the liquid absorbent member; and connecting the shell with the liquid absorbing piece, and vacuumizing the shell by using a vacuum device so that the liquid absorbing piece is contacted with the cathode and the workpiece to be decontaminated.
9. The decontamination method of claim 8, wherein the step of electrically treating the cathode and the workpiece to be decontaminated has a current density of 2A/cm2～20A/cm2。
10. The decontamination method of claim 8, wherein the step of electrically treating the cathode and the workpiece to be decontaminated comprises a step of electrically treating the cathode and the workpiece to be decontaminated with the electrolyte at a temperature of 30 ℃ to 90 ℃.
11. The decontamination method of claim 8, wherein the step of contacting the liquid absorbing member with the cathode and the work piece to be decontaminated has a distance of 1cm to 5cm between the cathode and the work piece to be decontaminated.
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