JP2018169184A - Decontamination device of radioactive concrete - Google Patents

Abstract

To decontaminate a radioactive concrete which can be installed in a short time at a simple facility without residing in a contaminated site, thereby reducing a risk of exposure.SOLUTION: A decontamination device 1 mixes a radioactive material sorbent, and includes: an electrode mat 3 laid on the surface of a radioactive concrete D; and electrode anchor 4 penetrating the electrode mat 3 while being insulated by an insulating bush 8 and injected into the radioactive concrete D; an electrolyte supply pipe 6 moves along a rifle of the electrode anchor 4 and having a discharge hole corresponding to a placing position of the electrode anchor 4 for causing an electrolyte solution 7 to be supplied through the radioactive concrete D ;an electrolyte tank 5 for storing the electrolyte liquid 7 supplied through this electrolyte supply pipe 6; and a power source 2 for applying a DC current between the electrode mat 3 and the electrode anchor 4. If the electrolyte solution 7 is caused to be saturated on the surface layer of the radioactive concrete D and the DC voltage is applied between the electrode mat 3 and the electrode anchor 4, an ionized radioactive material d can be induced, adsorbed, integrated, recovered, and processed by an electro-kinetic phenomenon.SELECTED DRAWING: Figure 1

Description

  The present invention absorbs and collects pollutants in concrete contaminated by radioactive materials attached to radioactive materials in radioactive power handling facilities such as nuclear power plants, nuclear fuel manufacturing facilities, and radioactive waste storage facilities. The present invention relates to an apparatus for decontaminating concrete.

When radioactive materials in the nuclear power generation, medical field, and academic field are contaminated by the radioactive material adhering to or adhering to the concrete that constitutes these related facilities and surrounding access facilities, there is a risk of radiation exposure. Prevent necessary work at the facility. In addition, work such as dismantling associated with the closure of these facilities requires a long period of time to complete because it must wait until the radioactivity is sufficiently attenuated. Contamination due to the adhesion of radioactive material on the concrete is limited to the surface, but the contamination due to activation extends from the surface of the concrete to the interior of about several tens of centimeters. Such decontamination work of radioactive concrete is the most important issue especially for accident countermeasures at nuclear power plants. If decontamination of radioactive concrete is carried out before demolition work and the reduction of radioactivity is promoted, the waiting time until the demolition work can be shortened.
Conventionally, there is a method for recycling activated concrete described in Patent Document 1. In this method, for example, the activated concrete block generated as solid waste due to renovation or dismantling of nuclear facilities such as nuclear power plants is crushed and immersed in heated nitric acid treatment liquid. While the metal component is recovered, the pulverized product obtained by solid-liquid separation is dried.
In addition, the method for decontamination of radioactively contaminated concrete described in Patent Document 2 uses a reinforcing bar in the concrete as a back electrode, a surface electrode on the surface of the concrete, and an electrolyte solution held on the surface of the surface electrode. Adhere the sheet. By applying negative pressure by sucking air between the surface of the concrete and the electrolyte solution holding sheet and flowing the electrolyte solution through the gap, and by passing a current between the back side electrode and the surface side electrode, A radioactive substance is moved to an electrode of concrete C by electrophoresis by an electric field, and concentrated in the concrete or taken out of the concrete. The electrolyte solution is sucked together with air to make the gap a negative pressure, returned to the electrolyte solution tank, and circulated by repeating the supply and recovery of this electrolyte solution.

JP 2012-229984 A Japanese Patent Laid-Open No. 2016-3904

In the conventional method described above, it is necessary to construct a large-scale facility for the decontamination process, and the radioactive concrete must be transported into the treatment facility as waste from which the structure has been demolished. Since decontamination cannot be performed, there is still a risk of exposure to workers when collecting and transporting radioactive concrete, and it is necessary to wait for a long time for the natural decay of radioactive materials contained in the radioactive concrete, which delays the disposal work.
In particular, as seen in a serious explosion accident at a nuclear power plant, when radioactive contamination causes high-concentration contamination around the facility, the route from the worker's station to the work site for handling the response after the accident. Since the exposure risk is high, the road surface and wall surface of the moving path cannot be adequately dealt with in order to ensure a safe flow line for accident handling.
Further, in the concrete decontamination method described in Patent Document 2, the radioactive substance is moved by electrophoresis between the electrodes, but the adsorption performance to the electrodes is low, and there is a possibility that the concentration in the vicinity of the electrodes may be stopped. Recovery is not easy. Since the reinforcing bar in the concrete is used for the back side electrode, when there is no reinforcing bar in the decontamination target region, it is necessary to drive the electrode considerably deeply in a manner of embedding in the concrete like a reinforcing bar. While the gap between the concrete surface and the electrolyte solution holding sheet is made negative by suction of air, the electrolyte solution is allowed to flow there, but the electrolyte solution is difficult to penetrate from the concrete surface to the deep part, and it is removed even to the deep activated concrete. There is a possibility that it cannot be dyed. In addition, air is sucked together with the electrolyte solution in order to make the gap negative, and the electrolyte solution is collected in the electrolyte solution tank, so that the circulation means including the treatment of contaminants in the electrolyte solution is complicated.
Therefore, the present invention does not require large-scale equipment, and an operator can efficiently collect radioactive materials while maintaining the structure of the radioactive concrete without being resident at the decontamination site by a simple installation work in a short time. A decontamination apparatus and decontamination method for radioactive concrete with a low exposure risk are provided.

In order to solve the above-described problems, in the present invention, a radioactive concrete decontamination apparatus 1 that adsorbs and recovers a radioactive substance d from a surface layer portion of the concrete C that is contaminated or activated by the radioactive substance d is configured. This decontamination apparatus 1 unfolds the electrode mat 3 mixed with the radioactive material adsorbent, covers the surface of the concrete C, and penetrates the electrode anchor 4 through the electrode mat 3 through the insulating bush 8 while insulating it. Type in C. The electrolytic solution 7 is supplied from the tank 5 through the electrolytic solution supply pipe 6, and the electrolytic solution 7 is injected into the concrete C through the electrode anchor 4 from the injection port corresponding to the placement position of the electrode anchor 4, and decontaminated. Infiltrate the concrete C in the target area. An electric field is formed between the electrode mat 3 and the electrode anchor 4 by the DC power source 2, and the ionized radioactive substance d in the concrete C infiltrated with the electrolytic solution 7 is adsorbed to the electrode mat 3 by an electrokinetic phenomenon and collected. .
An electrolytic solution penetration assisting device is provided that sucks the air inside the vacuum pot 10 that partially seals the surface of the concrete C by the vacuum blower 11 and promotes the penetration of the electrolytic solution 7 from the inside of the concrete C to the surface.
The decontamination apparatus 14 embeds the adsorption anchor 15 in the concrete C in the decontamination target area with a radioactive substance adsorbent interposed therebetween, and embeds the injection anchor 16 in the concrete C adjacent to the adsorption anchor 15. The electrolytic solution 7 is supplied from the tank 5 through the electrolytic solution supply pipe 6, and the electrolytic solution 7 is injected into the concrete C through the injection anchor 16 from the injection port corresponding to the placement position of the injection anchor 16, thereby decontamination. Infiltrate the concrete C in the target area. An electric field is formed between the adsorption anchor 15 and the injection anchor 16 by the DC power source 2, and the ionized radioactive substance d in the concrete C infiltrated with the electrolytic solution 7 is adsorbed around the adsorption anchor 15 by an electrokinetic phenomenon, and recovered and disposed. To do.
The electrode anchor 4 or the adsorption anchor 15 includes a rifle through which the electrolytic solution 7 is transmitted.
The electrode anchor 4 or the adsorption anchor 15 is made of a tubular material, and is connected to the injection port of the electrolyte solution supply pipe 6 so that the hollow interior communicates, and has a discharge port that opens to the outside and discharges the electrolyte solution 7.

  In the present invention, it can be installed without taking much time in decontamination with simple equipment, and can effectively adsorb pollutants around the electrode, without moving the radioactive concrete to be decontaminated, and unattended in the field. Since decontamination work can be carried out, it is not necessary to stay at the decontamination site for a long time from installation preparation to decontamination work, and it is easy to unmanned installation work by remote control with a robot, etc. It can be reduced as much as possible, and the radiation level can be reduced by simple decontamination of radioactive concrete, and even after a serious accident such as an explosion at a nuclear power plant or nuclear fuel manufacturing facility, it is possible to respond to the site. The line can be secured effectively.

It is a schematic block diagram of the decontamination apparatus concerning 1st Example of this invention. It is a schematic block diagram of the electrolyte solution penetration auxiliary device concerning the 2nd example of the present invention. It is a schematic block diagram of the decontamination apparatus concerning 3rd Example of this invention.

Embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, the decontamination apparatus 1 according to the first embodiment of the present invention removes the radioactive concrete D in which the concrete C constituting the floor and walls of the facility is contaminated by the radioactive material adhering or radiation activation. It is dyed. The decontamination apparatus 1 is a DC power source 2, an electrode mat 3 that is a first electrode member connected to the negative electrode side of the power source 2, and a second electrode member connected to the positive electrode side of the power source 2. An electrode anchor 4, an electrolyte solution tank 5 that stores an electrolyte solution 7 that permeates into the radioactive concrete D, and an electrolyte solution supply pipe 6 that is connected to the electrolyte solution tank 5 are provided. The power source 2 has a voltage of about several VDC necessary for ionization of radioactive materials by electrolysis, a voltage of about several V to 50 V necessary for the expression of effective electrophoretic phenomenon and electroosmotic flow, and a current of several A or less. Since it is sufficient to generate a small amount, a small capacity is sufficient.

  The electrode mat 3 is laid down in close contact with the surface of the radioactive concrete D to be decontaminated. The electrode mat 3 has a sheet shape, and is obtained by mixing or adhering a radioactive substance adsorbent to a general electrode material such as metal or carbon. As the radioactive material adsorbent, zeolite, flame charcoal, ion exchange resin, layered clay mineral, activated carbon or the like having the ability to adsorb radioactive material is applied. Prussian blue is particularly effective against radioactive cesium.

  The electrode anchor 4 penetrates the electrode mat 3 while being insulated by the insulating bush 8, and a plurality of electrode anchors 4 are driven into the radioactive concrete D at approximately equal intervals of about several tens of cm to 1 m. The electrode anchor 4 is a concrete anchor made of a conductive metal material. The insertion depth of the electrode anchor 4 is changed in accordance with the depth distribution of the radioactive substance concentration of the sampling core by performing core boring or the like on the concrete D to be decontaminated in advance. For example, when the contamination is concentrated on the surface of the concrete D, the driving depth is about several centimeters. However, when the contamination reaches several tens of centimeters from the surface due to activation, the driving depth is increased by using the long electrode anchor 4. Take. In addition, when the concrete D to be decontaminated is reinforced concrete, the electric corrosion of the reinforcing bars and the neutralization of the concrete may occur due to energization, and the facility before demolition may be weakened. Consider strength degradation in determining insertion depth.

  The electrolytic solution 7 in the electrolytic solution tank 5 is supplied to the position of the electrode anchor 4 of the radioactive concrete D through the electrolytic solution supply pipe 6. The electrolyte supply pipe 6 is provided with a number of drip feed water discharge holes corresponding to the placement positions of the electrode anchors 4. The electrolyte 7 instilled from the electrolyte supply pipe 6 penetrates and diffuses the surface and the inside of the radioactive concrete D through the rifle of the electrode anchor 4, and the radioactive contaminant D in the radioactive concrete D is eluted and ionized by applying a voltage. To do. In addition, since the degree of expression of the electrokinetic phenomenon of the electrolytic solution depends on the amount of current, the application of the electrolytic solution is preferable to water in order to increase the conductivity of the radioactive concrete D to be decontaminated. When the pollutant is radioactive cesium, salts that can be easily replaced with radioactive cesium, such as potassium salt and ammonium salt, may also be used to promote elution.

In the decontamination apparatus 1 of this embodiment, an electrode mat 3 is laid on the surface of radioactive concrete D of a facility contaminated by radioactive material adhering or activation by radiation irradiation, and an insulating bush 8 is provided on the electrode mat 3. The electrode anchor 4 is penetrated while being insulated and driven into the radioactive concrete D. The discharge hole of the electrolyte supply pipe 6 is arranged so as to match the electrode anchor 4, and the electrolyte solution 7 of the electrolyte tank 5 is instilled through the rifle of the electrode anchor 4 to penetrate from the surface of the radioactive concrete D to the inside. Then turn on the power 2. A direct current voltage is applied between the electrode mat 3 and the electrode anchor 4, and the radioactive substance d contained in the surface and inside of the radioactive concrete D is eluted and electrolyzed by electrolysis. Electrophoresis in the direction of the arrow in FIG. Then, it is guided to the electrode mat 3 by the electroosmotic flow of the electrolyte solution 7 and adsorbs and accumulates on the radioactive material adsorbent. Therefore, the adsorbent obtained by collecting and concentrating the radioactive substance d along with the removal of the electrode mat 3 can be accommodated in a drum can and disposed of as radioactive waste.
When the radioactive substance d to be decontaminated is anionized and adsorbed, the polarity of the power source 2 is reversed to make the electrode mat 3 positive and the electrode anchor 4 negative.

  The electrolyte solution penetration assisting device 9 shown in FIG. 2 may be added to the previous decontamination device. In addition, in FIG. 2, the decontamination apparatus 1 is not shown clearly. In the figure, an electrolytic solution penetration assisting device 9 includes a vacuum pot 10, a vacuum blower 13 communicating with the vacuum pot 10 via a mist trap 11 through a communication pipe 11 a, and a bag filter 14 connected to the vacuum blower 13. . The vacuum pot 10 is partially covered on the radioactive concrete D, and the inside is almost sealed. The vacuum pot 10 includes wheels 10a that facilitate movement. The vacuum blower 11 communicates with the vacuum pot 10 and sucks the air inside the vacuum pot 10. The mist trap 11 removes droplets such as the electrolyte 7 from the internal air of the vacuum pot 10. The bag filter 14 removes dust from the suction air of the vacuum blower 13 and discharges it.

  In the radioactive concrete D, an insertion hole for the electrode anchor 4 of the decontamination apparatus 1 is made in advance, and the electrolytic solution 7 of the electrolytic solution tank 5 is injected into the radioactive concrete D through the electrolytic solution supply pipe 6 and closed with putty or the like. . In the electrolytic solution penetration assisting device 9, the vacuum pot 10 is almost hermetically mounted on the radioactive concrete D into which the electrolytic solution 7 is injected, and the internal air is sucked by the vacuum blower 13 to make the inside of the vacuum pot 10 have a negative pressure. Thus, the penetration diffusion of the electrolyte solution 7 from the inside of the radioactive concrete D toward the surface (arrow in FIG. 2) is promoted. After the vacuum pot 10 is appropriately moved within the decontamination target region and the electrolyte 7 is sufficiently diffused into the radioactive concrete D, the putty of the insertion hole for the electrode anchor 4 of the radioactive concrete D is removed, As in the embodiment, the decontamination apparatus 1 is installed and decontamination work is performed.

  The decontamination apparatus 14 of 3rd Example is shown in FIG. In the figure, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted. In the present embodiment, the decontamination apparatus 14 decontaminates the radioactive concrete D in which the concrete C constituting the walls and floors of the facility is contaminated by the radioactive material adhering or activation by radiation irradiation. An adsorption anchor 15 that is a first electrode member is connected to the negative electrode side of the power supply 2, and an injection anchor 16 that is a second electrode member is connected to the positive electrode side. The adsorption anchor 15 and the injection anchor 16 are concrete anchors made of a conductive metal material. Around the adsorption anchor 15, a radioactive substance adsorbent 17 is filled and held in an insertion hole instead of a sleeve of a general concrete anchor. The injection anchor 16 has a drip water supply discharge hole of the electrolyte solution supply pipe 6 for injecting the electrolyte solution 7 of the electrolyte solution tank 5, and is instilled into the radioactive concrete D through the rifle of the injection anchor 16.

  In this decontamination apparatus 14, a large number of adsorption anchors 15 and injection anchors 16 are arranged alternately at substantially equal intervals of about several tens of cm to 1 m, and are placed in the radioactive concrete D, and electrolysis is performed in the insertion holes of the adsorption anchors 15. The electrolytic solution 7 in the electrolytic solution tank 5 is instilled through the liquid supply pipe 6 to penetrate the surface and inside of the radioactive concrete D, and the power supply 2 is turned on. A direct current voltage is applied between the adsorption anchor 15 and the injection anchor 16, and the radioactive substance d contained in the radioactive concrete D is eluted and ionized by electrolysis. Electrophoresis and electrolyte along the direction of the arrow in FIG. Is induced, adsorbed and accumulated on the radioactive material adsorbent 17 of the adsorption anchor 15.

The electrode anchor 4 and the injection anchor 16 are communicated by connecting the electrolyte supply pipe 6 as a tubular body having a discharge port in the middle instead of the rod-shaped body having the rifle. It is good also as a structure which inject | pours 7 into concrete from a discharge outlet.
The radioactive concrete applied in each embodiment of the present invention includes not only cement but also one produced with asphalt.

DESCRIPTION OF SYMBOLS 1 Decontamination apparatus 2 Power supply 3 Electrode mat 4 Electrode anchor 5 Electrolyte tank 6 Electrolyte supply pipe 7 Electrolyte 8 Insulation bush 9 Electrolyte penetration auxiliary device 10 Vacuum pot 10a Wheel 11 Mist trap 11a Communication pipe 13 Vacuum blower 14 Decontamination Device 15 Adsorption anchor 16 Injection anchor 17 Radioactive material adsorbent C Concrete D Radioactive concrete d Radioactive material

Claims (5)

In the decontamination equipment for radioactive concrete, which adsorbs and collects radioactive material from the surface layer of concrete contaminated or activated by radioactive material,
An electrode mat developed to cover the surface of the concrete and mixed with a radioactive substance adsorbent,
An electrode anchor that penetrates the electrode mat while being insulated with an insulating bush, and is placed in concrete;
A direct current power source for forming an electric field between the electrode mat and the electrode anchor;
An electrolyte that penetrates into the concrete in the decontamination area;
An electrolyte supply pipe having an inlet corresponding to a placement position of the electrode anchor for injecting the electrolyte into the concrete through the electrode anchor;
A tank for storing the electrolyte supplied through the electrolyte supply pipe;
An apparatus for decontaminating radioactive concrete, wherein an ionized radioactive substance in the concrete infiltrated with the electrolyte is adsorbed to the electrode mat by electrokinetic phenomenon and recovered and disposed of.   A vacuum pot that partially seals the surface of the concrete, and a vacuum blower that sucks the air inside the vacuum pot and promotes the penetration of the electrolyte from the inside of the concrete to the surface. The radioactive concrete decontamination apparatus according to claim 1. In the decontamination equipment for radioactive concrete, which adsorbs and collects radioactive material from the surface layer of concrete contaminated or activated by radioactive material,
An adsorption anchor embedded in the concrete in the decontamination target area with a radioactive substance adsorbent interposed in the surroundings;
An injection anchor embedded in concrete adjacent to the adsorption anchor;
A direct current power source for forming an electric field between the adsorption anchor and the injection anchor;
An electrolyte that penetrates into the concrete in the decontamination area;
An electrolyte supply pipe having an injection port corresponding to a placement position of the injection anchor to infiltrate the electrolyte into the concrete through the injection anchor;
A tank for storing the electrolyte supplied through the electrolyte supply pipe;
The radioactive concrete decontamination apparatus, wherein an ionized radioactive substance in the concrete infiltrated with the electrolytic solution is adsorbed on the adsorption anchor by an electrokinetic phenomenon and recovered and disposed of.   4. The radioactive concrete decontamination apparatus according to claim 1, wherein the electrode anchor or the adsorption anchor includes a rifle through which the electrolytic solution is transmitted.   The electrode anchor or the adsorption anchor is made of a tubular material, and has an outlet for connecting the inlet of the electrolyte supply pipe to communicate with the hollow interior and opening the exterior to the outside to discharge the electrolyte. The decontamination apparatus for radioactive concrete according to claim 1 or 3.

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