JPH0587983A - Decontamination method and device for radioactive material deposition surface - Google Patents

Abstract

PURPOSE:To promote grinding and removing of radioactive material an adsorb a part of the radioactive material in zeolite particles to maintain stable state by blowing mixture fluid of zeolite particles and compressed air for grinding the radioactive material and contacting the radioactive material to zeolite particles and by recovering it. CONSTITUTION:With the action of a transportation means, a radioactive material deposition body X is transported and put on a rotation disk 52 of a roptation means 5. With the action of a blast fluid supply means 1, the mixed fluid of zeolite particles 2 with compressed air is blown out of a blowout nozzle 3 to the surface of the deposition body X. The radioactive material deposited on the surface and a part of the surface are ground and removed and the radioactive material is adsorbed on the particles 2 in a stable state. The ground and removed layer is dropped on a recovery means 4. At this moment, by operating the rotation means 5 and the transportation means 6 simultaneously and conducting simultaneously the rotation operation of the deposition body X on the rotation disk 52 and elevation operation of the nozzle 3, the position ground and removed by the particles 2 spreads the whole surface of the deposited body X and thus decontamination of radioactives are made widely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for decontaminating a surface on which radioactive substances are attached, and more particularly to decontaminating the surface of an attached substance on radioactive materials generated in facilities related to nuclear power generation.

[0002]

2. Description of the Related Art In nuclear power generation facilities, when handling articles and the like in a radiation environment, it is necessary to reduce the adhesion of radioactive substances.

When transferring an article to which a radioactive substance is attached, a decontamination work for the contaminated surface (a work for removing the radioactive substance) is required in order to prevent diffusion.

For example, as a method for decontaminating radioactive substances adhering to the surface of a vitrified container (canister) obtained by vitrifying a high-level waste liquid, a method of spraying pressurized water onto the surface of the container and washing with water Is being considered. By carrying out this decontamination treatment, it is intended to prevent the diffusion of radioactive substances during the transfer to the storage location.

[0005]

However, in the method of washing the surface polluted with radioactive substances with water, since the radioactive substances are contained in the miscellaneous wastewater generated by washing, the miscellaneous wastewater is filtered or concentrated. Therefore, it is necessary to ensure that radioactive substances are separated from each other and to secure various equipment to carry out these treatments.For large amounts of water separated from radioactive substances, control whether radioactive substances are mixed or not. Need to do enough.

In view of such circumstances, the present invention omits the use of washing water, and adsorbs radioactive substances at the time of decontamination to prevent diffusion and also reuses materials used during decontamination work. It is an object.

[0007]

[Means for Solving the Problems] In order to achieve such an object, four means are proposed. The first means is to spray a mixed fluid of zeolite particles and pressurized air onto the surface to which the radioactive substance is attached to grind the radioactive substance, attach the ground radioactive substance to the zeolite particle, and collect the zeolite particle. This is a method for decontaminating the surface to which radioactive substances are attached. The second means is a method for decontaminating a radioactive material-adhered surface, in which zeolite particles in a state where the radioactive material is adhered by the treatment by the first means are diverted to an adsorbent for the radioactive material. A third means is a blast fluid supply means for transferring a mixed fluid of zeolite particles and pressurized air, and a mixed fluid of zeolite particles and pressurized air which is connected to the blast fluid supply means and which is provided on the surface of the radioactive substance adhering body. The decontamination device for a radioactive substance adhered body is provided with a jet nozzle for jetting the jetted particles toward the target and a collecting means for collecting the jetted zeolite particles. The fourth means comprises a rotating means for mounting and rotating the radioactive substance deposit, and a moving means for operating the radioactive substance deposit or the ejection nozzle along the rotation center line in conjunction with the rotating means. Is added to the third means to decontaminate the radioactive substance deposit.

[0008]

In the first means and the third means, the surface on which the radioactive substance is attached is ground by spraying the zeolite particles, and the separation of the radioactive substance from the surface is promoted. In addition, a part of the radioactive substance is adsorbed to and adsorbed on the zeolite particles to be in a stabilized state and is collected together with other zeolite particles. In the second means, the recovered zeolite particles are diverted as an adsorbent for radioactive substances, and even if some radioactive substances are adhered and adsorbed in this case, the performance at the time of adsorption of radioactive substances and after adsorption There is little influence on the processing of. In the fourth means, the zeolite particles are jetted to the entire surface of the radioactive substance deposit by rotating the radioactive substance deposit and moving the jet nozzle, and the radioactive substance is ground and recovered.

[0009]

1 and 2 show one embodiment of an apparatus for decontaminating a surface having a radioactive substance attached thereto. In these FIGS. 1 and 2, reference numeral X is a radioactive substance adhering body (canister), Y is a particle collection container, 1 is a blast fluid supply means, 2 is zeolite particles (silica gel particles), 3
Is a jetting nozzle, 4 is a collecting means (hopper), 5 is a rotating means, 6 is a moving means, and 7 is a transferring means.

As shown in FIG. 1, the blast fluid supply means 1 supplies a storage container 11 and a hopper 12 for storing the zeolite particles 2, a feeder 13 for feeding the zeolite particles 2 from the hopper 12, and pressurized air. A pressurized air supply system 14, a mixing pipe 15 connected to the feeder 13 and the pressurized air supply system 14 to mix the zeolite particles 2 and pressurized air into a mixed fluid, the mixing pipe 15 and the ejection nozzle. 3 and a blast fluid supply pipe 16 that connects the same.

As shown in FIG. 1, the collecting means 4 is a hopper or the like arranged below the ejection nozzle 3, the rotating means 5 and the moving means 6, and the granular material downflow nozzle 41 and the shutter 4 are provided.
2 and the like are added and dropped into the particle collecting container Y.

The rotating means 5 is, as shown in FIG. 1, a support base 51 arranged near the jet nozzle 3 and the moving means 6.
And a rotary disk 52 on which the radioactive substance deposit X is horizontally rotatably mounted on the support base 51, a rotary drive source (rotary motor) 53 for rotating the rotary disk 52, and the like. To be done.

As shown in FIG. 2, the moving means 6 includes a bracket 61 integral with the support base 51, and the bracket 61.
A screw rod 62 that is horizontally rotatable and arranged in an upright state
And a lifting table 63 that moves up and down by being screwed onto the screw rod 62.
And a guide 64 for guiding the vertical movement of the lift table 63,
A raising / lowering drive source (elevating / lowering motor) 65 arranged on the bracket 61, and a rotating force of the raising / lowering drive source 65
Transmission mechanism 66 such as a gear for transmitting to the
And an ascending / descending bracket 67 for supporting the jet nozzle 3 and the like.

As shown in FIG. 1, the transfer means 7 is an overhead traveling crane or the like, and is provided with a lifting tool 71 and the like which is detachably connected to the radioactive substance deposit X.

In the decontamination apparatus having the above-mentioned structure, the transfer means 7 is operated to transfer the radioactive substance deposit X onto the turntable 52 of the rotating means 5 to place it thereon, and to supply the blast fluid. When the means 1 is operated to jet the zeolite particles 2 as a mixed fluid with pressurized air from the jet nozzle 3 onto the surface of the radioactive substance deposit X, the radioactive substance adhering to the surface and a part of the surface are ground. After that, the scraping and peeling scraps are dropped into the collecting means 4.

In this case, when the rotating means 5 and the moving means 6 are simultaneously operated to perform the rotating operation of the radioactive substance deposit X on the turntable 52 and the elevating operation of the ejection nozzle 3, the zeolite The position where the particles 2 are ground and peeled off spreads over the entire surface of the radioactive substance deposit X, and the radioactive substance is removed (decontaminated) over a wide range. Also,
It is considered that the radioactive material in the fine particle state is attached to the surface of the zeolite particle 2, and a part of the radioactive material is stabilized by adsorption due to the zeolite particle 2 being the adsorbent.

Zeolite particles 2 dropped in the recovery means 4
The radioactive substance and the radioactive substance are collected in the granular material collecting container Y via the granular material flow-down nozzle 41 by opening the shutter 42.

The zeolite particles 2 recovered in the particle recovery container Y are in a state in which a small amount of radioactive substance is adhered or adsorbed on the surface thereof, and this is used as it is as an adsorbent for radioactive substance. Can be diverted.

At the time of diversion, even if some radioactive substance is attached and adsorbed, the amount of radioactive substance adhering to the surface of the radioactive substance adherent X itself is small,
There is little influence on the performance at the time of subsequent adsorption of radioactive substances.

Further, in order to adsorb the radioactive substance to the zeolite particles 2 before and after conversion, the treatment after the adsorption, the isolation, the storage, and the regeneration treatment if necessary, are performed by the same treatment, It does not cause problems in handling.

On the other hand, FIG. 3 shows another embodiment of the apparatus for decontaminating the surface to which radioactive substances are attached. In FIG. 3, the rotating means 5 is provided with a transmission mechanism 54 such as a gear for transmitting the rotational force of the rotation drive source 53 and a drive shaft 55 on the support base 51, and the drive shaft 55 rotates at the upper end. The board 52 is attached to rotate the radioactive substance deposit X, and the moving means 6 is a lifter 68 that moves the support base 51 up and down. In addition, decontamination work
The ejection nozzle 3 is disposed inside the isolation wall 73 so that the isolation wall 73 is arranged in the cell chamber surrounded by the shielding wall 72 and the radioactive substance deposit X above the recovery means 4 is shielded. The radioactive substance deposit X is moved up and down while being rotated so that the height of the radioactive substance deposit X is changed and the mixed fluid of the zeolite particles 2 is jetted to the entire surface to I am trying to remove it.

In these examples, the compressed air ejected together with the zeolite particles 2 is set to be discharged. In this case, however, in order to remove the radioactive substance mixed in the removed air, It is also possible to use zeolite particles as a filter and appropriately recover the zeolite particles in the particle collecting container Y.

[0023]

According to the first aspect of the present invention, that is, the method for decontaminating a radioactive substance-adhered surface according to the first aspect of the present invention, a mixed fluid of zeolite particles and pressurized air is sprayed onto the radioactive substance-adhered surface to release radioactive substances. The present invention has the following effects because it is intended to grind the powder and to attach the ground radioactive substance to the zeolite particles and to collect the zeolite particles. (1) The grinding action at the time of spraying promotes the grinding and peeling of the radioactive substance, and a part of the radioactive substance is not adsorbed and adsorbed on the zeolite particles and does not fly outside.
It can be in a stabilized state. (2) Due to the large energy at the time of spraying the zeolite particles, the decontamination effect of the radioactive substance can be enhanced as compared with the time of washing with water. (3) Compared with the decontamination method by washing with water, water is not used during decontamination, so decontamination work can be easily performed. The second invention, that is, the method for decontaminating a radioactive substance-adhered surface according to claim 2, diverts the zeolite particles to which the radioactive substance has been attached by the treatment step of the first invention to an adsorbent for the radioactive substance. Therefore, the following effects are obtained. (1) With the decontaminated radioactive substance attached or adsorbed to the recovered zeolite particles, the radioactive substance is reused as an adsorbent for the radioactive substance without diffusing, and in this case, some radioactive substance is attached and adsorbed. However, it does not affect the adsorption characteristics of radioactive substances. (2) Even when the adsorption of radioactive substances is divided into several times, the use of treating radioactive substances is the same, so the isolation, storage, and regeneration treatments after adsorption are performed by the same treatment. It does not cause problems in handling. (3) Compared with the decontamination method by washing with water, generation of new waste based on decontamination can be suppressed. A third invention, that is, a decontamination device for a radioactive substance-adhered surface according to a third aspect, comprises a blast fluid supply means for transferring a mixed fluid of zeolite particles and pressurized air, and a mixture of zeolite particles and pressurized air. Since it is equipped with a jet nozzle for jetting the fluid toward the surface of the radioactive substance-attached body and a collecting means for collecting the zeolite particles, the same effect as that of the first aspect of the invention is exhibited, and the zeolite particles and the radioactive The substance can be recovered. Fourth invention,
That is, the apparatus for decontaminating a radioactive substance-attached surface according to claim 4 includes a rotating unit that mounts and rotates the radioactive substance-attaching body, and a moving unit that moves the radioactive substance-attaching body or the ejection nozzle along the rotation center line. In addition to the effect according to the third aspect of the present invention, in order to improve the decontamination efficiency of a desired radioactive substance deposit by ejecting zeolite particles all over the entire surface of the radioactive substance deposit. You can

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a decontamination apparatus for radioactive substance adherents according to the present invention.

FIG. 2 is a perspective view showing details of moving means in FIG.

FIG. 3 is a front sectional view showing another embodiment of the apparatus for decontaminating radioactive substance adherents according to the present invention.

[Explanation of symbols]

 X Radioactive substance adherent (canister) Y Granule recovery container 1 Blast fluid supply means 2 Zeolite particles (silica gel granules) 3 Jet nozzle 4 Recovery means (hopper) 5 Rotating means 6 Transfer means 7 Transfer means 11 Storage container 12 Hopper 13 Feeder 14 Pressurized Air Supply System 15 Mixing Pipe 16 Blast Fluid Supply Pipe 41 Granule Downflow Nozzle 42 Shutter 51 Supporting Stand 52 Rotating Disk 53 Rotational Drive Source (Rotating Motor) 54 Transmission Mechanism 55 Drive Shaft 61 Bracket 62 Screw Rod 63 Lifting table 64 Guide 65 Lifting drive source (lifting motor) 66 Transmission mechanism 67 Lifting bracket 68 Lifter 71 Lifting tool 72 Shielding wall 73 Isolation wall

Claims (4)

[Claims] 1. A method of grinding a radioactive substance by spraying a mixed fluid of zeolite particles and pressurized air onto a surface to which the radioactive substance is attached, adhering the ground radioactive substance to the zeolite particle, and collecting the zeolite particle. A method for decontaminating a surface having a radioactive substance attached thereto. 2. A method for decontaminating a radioactive substance-adhered surface, characterized in that the zeolite particles having the radioactive substance adhered by the treatment according to claim 1 are diverted to an adsorbent for the radioactive substance. 3. A blast fluid supply means for transferring a mixed fluid of zeolite particles and pressurized air, and a mixed fluid of zeolite particles and pressurized air connected to the blast fluid supply means on the surface of the radioactive substance adhering body. An apparatus for decontaminating radioactive substance deposits, comprising: an ejection nozzle for ejecting the ejected zeolite particles; and a recovery means for recovering the ejected zeolite particles. 4. A rotating means for mounting and rotating the radioactive substance deposit, and a moving means for moving the radioactive substance deposit or the jet nozzle along a rotation center line in conjunction with the rotating means. The decontamination device for a radioactive substance deposit according to claim 3, which is characterized in that.