JPS6120898A - Device for solidifying and treating radioactive gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radioactive gas immobilization processing apparatus that ionizes a free to-be-processed gas in a nuclear fission product gas and injects it into a metal substrate.

[Technical background of the invention and its problems] Nuclear facilities, such as nuclear fuel reprocessing plants, have the potential to cause wide-ranging and long-term effects if harmful amounts of radioactivity are released into the environment. It is mandatory to ensure safety much more strictly than in general industry in Brazil.

Reprocessing plants recover uranium and plutonium from spent fuel, but at the same time they must properly dispose of accompanying radioactive waste, including fission products. Among radioactive waste, gaseous waste is krypton-85 (hereinafter referred to as Kr-85).
85), but because it has a long half-life of 10.7 years, if nuclear power generation is expected to increase in the future, there is a risk that it will lead to global pollution in the future. .

Therefore, along with the recovery technology, an important issue is the recovered Kr-8
, 5, how to safely store or dispose of them. Conventionally, methods have been considered to permanently preserve radioactive waste gas by sealing it in pressure-resistant pressure containers such as cylinders.

However, the method of sealing in a pressure vessel has problems in terms of long-term safe storage. For example, pressure vessels are required by law to undergo periodic pressure tests, which have the disadvantage of requiring complicated and dangerous work such as transferring stored gas each time.

On the other hand, for the treatment of gaseous waste Kr-85, in addition to the method of storing it in a pressure vessel such as a cylinder, methods of adsorption to zeolite, ionization injection fixing method, etc. have been proposed.

However, the bomb storage method and the zeolite adsorption method have many problems that need to be improved before they can be put to practical use.

- The ion implantation method not only allows disposal operations to be carried out at room temperature and low pressure, but is also considered to be superior to other methods in terms of long-term safety.

FIG. 4 is a sectional view showing an outline of a conventional implantation apparatus for ionizing and implanting radioactive gas, and FIGS. 5 and 6 are cross-sectional views of the apparatus shown in FIG. 4.

Hereinafter, a conventional radioactive gas immobilization processing apparatus will be explained with reference to FIGS. 4 to 6.

A cooling pipe 3 is provided in the ionization chamber 2 provided in the cylindrical container 1.
A cylindrical electrode 5 to which a lead wire 4 is attached is arranged at its center. The cooling pipe 3 and the lead
The wire 4 is insulated and sealed from the top cover 7 with an insulator 6 such as a barmetal seal. In addition, the container 1
The upper lid 7 has a vibrator 9 for introducing Kr-85 gas.
is connected via a valve 8, and a vibrator 11 for exhausting the inside of the container 1 is connected via a valve 10. Further, a cooling pipe is wound around the outer peripheral surface of the container 1. Note that reference numeral 14 is a cumulative layer consisting of an ion-implanted Kr-85 ion layer and a coating layer sputtered by the electrode; in FIGS. Each figure shows sputtered ions flying out.

Next, a method for fixing and disposing Kr-85 gas in the above apparatus will be explained.

That is, in FIG. 4, the inside of the container 1 is equipped with an exhaust device (not shown) connected to an exhaust pipe 11, such as an ion pump,
After evacuating to a desired vacuum level, e.g., 5X 10-' T, orr fl., using an axial flow molecular pump, an oil diffusion pump, etc., the valve 10 is closed to maintain a constant pressure inside the container 1, and then the valve 8 is closed. 1 (r-85 gas is written from a cylinder (not shown) opened and connected to the vibrator 9, and the pressure inside the container 1 is constant, e.g. 0.17 orr, and the r-85
Once the gas is filled, valve 8 is closed.

Further, a cooling medium such as water is caused to flow through the cooling pipe and 12 to cool the nickel electrode 5 and the container 1, for example. Kr is connected between the container 1 and the lead wire 4 connected to the nickel electrode 5.
A high voltage of, for example, 2 to 5 kV capable of impacting with sufficient energy to inject and implant -85 is applied to the nickel electrode 5 by a direct current high voltage power supply (not shown) whose polarity can be alternately exchanged. 2 to 5 k plus nickel electrode 5
When a high voltage of V is applied, it is ionized) (r
-85 ions 15 are injected and planted into the inner surface of the container 1 as shown in FIG. 5, and when a negative high voltage of 2 to 5 kV is applied to the nickel electrode 5, Then, the Kr-85 ions 15 impact the surface of the nickel electrode 5 and sputter the material of the electrode 5, and the sputtered ions physically coat the Kr-85 ions 15 planted on the inner surface of the container 1. Ru.

In this way, a high positive voltage and a high negative voltage of 2 to 5 kV are applied to the nickel electrode 5 at regular intervals, for example, for 5 seconds during coating, and for 1 second when implanting Kr-85 ions 15. As a result, a Kr-85 ion layer and a metal coating layer of nickel ions are accumulated on the inner surface of the cylindrical container 1 to form a cumulative layer.

However, with conventional radioactive gas ionization implantation and fixation equipment, the ionization fixation processing equipment is operated regardless of whether the amount of radioactive gas to be treated is large or small, and the equipment is stopped when the fixation process is completed. Become. If the ionization fixation processing equipment is online (II), it is undesirable to repeatedly start and stop the equipment from the viewpoint of equipment maintenance, power consumption, and labor saving, and if anything, it is preferable to run the equipment continuously. This is desirable.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to treat radioactive gases such as Kr-
An object of the present invention is to provide a radioactive gas immobilization processing apparatus in which the ionization processing amount, that is, the processing capacity of the ionization fixation processing apparatus can be adjusted in accordance with the processing role of 85.

[Summary of the Invention] ゛The radioactive gas immobilization processing apparatus according to the present invention has a cylindrical electrode disposed in a cylindrical container into which a radioactive gas to be treated is introduced, and a cylindrical electrode having two to five electrodes having different polarities between the cylindrical electrode and the container. A high voltage of kV is applied to ionize the radioactive gas and cause a glow discharge, and a negative high voltage of -2 to -5 kV is applied to the electrode.
kV is applied □, and the ions are bombarded to generate sputtering ions □ from the electrode surface to form a coating layer on the inner surface of the container.

After that, a negative high voltage of -2 to -5 kV is applied to the cylindrical container to inject the ions into the inner surface of the container to form an ionized layer, and the coated layer and the ionized layer are alternately accumulated. It is a device that captures images. The inside of the cylindrical container of this device forms a plurality of electrically insulated ionization chambers, and each ionization chamber is provided with a member for selectively or simultaneously injecting ionization.

[Embodiments of the Invention] Hereinafter, the radioactive gas immobilization processing apparatus of the present invention will be described in detail with reference to FIGS. 1 to 3.

That is, FIG. 1 is a sectional view showing a first embodiment of the radioactive gas immobilization processing apparatus of the present invention, and the same parts as in FIG. 4 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

Electrode 20.21.2 arranged in the center of the cylindrical container 1
2 is divided into three equal parts along the axial direction, and an insulator 23 is interposed in each divided part. And these electrodes 2
0.21.22 are electrically insulated to form a first ionization chamber 12, a second ionization chamber 33, and a third ionization chamber 34, respectively. Also, each electrode 20. ．． 21.
Three insulators 24 made of, for example, Hermedic seals are provided on the side surface of the container 1 opposite to the insulators 22.
Lead wires 25, 26, 27 are connected independently through the wires 4, and switches 28, 29, 30 are attached to these lead wires 25, 26, 27. The other ends of these switches 28, 29, 30 are connected to a high voltage supply power source 31 that applies a high voltage of, for example, 2 to 5 kV while changing the polarity at regular intervals, and the other end of the power source 31 is connected to the container 1. has been done. In this way, the first embodiment has the same structure as that in FIG. 1 (same reference numerals) except that it is divided into a first ionization chamber 32, a second ionization chamber 33, and a third ionization chamber 34. There is.

Next, a method for actually ionizing l(r-85 gas) as an example of a radioactive gas to be processed using the processing apparatus in the first embodiment will be described in detail.

Note that this is an example in which nickel is used as the material for the electrodes 20, 21, and 22. When the amount of Kr-85 gas is relatively small, 'r-8
5 gas ionization and fixation processing, switch 28
is closed (switches 29 and 30 are open), and high voltages of different polarities, for example, 2 to 5' kV, are applied at regular intervals between the container 1 and the electrodes 20 by the high voltage power supply 31. Then, by repeating the formation of a coating layer on the inner wall of the container 1 by sputtering the electrode 20 and the formation of an ionization layer in the first ionization chamber 32 by the method shown in FIGS. 5 and 6, an ionization layer is formed. 14 and Kr −
85 ion implantation fixation process is performed.

In addition, when processing a large amount of Kr-85 gas, by also closing the switch 29.30, ion implantation and immobilization can be performed simultaneously in the second ionization chamber 33 and the third ionization chamber 34 using the same method. can be processed.

In this way, some of the Kr-85 gas treated is
That is, by adjusting the processing capacity in response to fluctuations in the processing amount, continuous operation can be performed with an aim to average the processing amount.

FIG. 2 is a sectional view showing a second embodiment of the radioactive gas immobilization processing apparatus of the present invention. In FIG. 2, parts that are the same as those in FIG. 1 are designated by the same reference numerals, and explanations of overlapping parts will be omitted.

This embodiment differs from the embodiment shown in FIG. 1 by using a common hollow cylindrical electrode 5, dividing the cylindrical container 1 into three parts, and interposing an insulator 23 between the divided surfaces to electrically insulate the first part. An ionization chamber 32, a second ionization chamber 33, and a fiI3(7) ionization chamber 34 are formed. Further, an insulator is provided on the bottom of the container 1, and the electrode 5 is connected to the high voltage supply power source 3 through the insulator 24.
It is connected to one end of 1. Further, lead wires are connected from the other end of the 14-voltage power supply 31 to the containers 1 of the first, second, and third ionization treatments 2, 33, and 34 via switches 35, 36, and 37. The other configurations are the same as in FIG. 1.

In the apparatus having such a configuration, the switch 28 is closed, the switches 29 and 30 are left open, and the first ionization chamber 3 is opened in the same manner as explained in FIG.
In step 2, Kr-85 can be immobilized by ion implantation.

FIG. 3 shows a third embodiment of the invention. This third embodiment has substantially the same structure as the apparatus shown in FIGS. 1 and 2, except that the container and the electrodes are shown separately. According to this example, Kr −
85 ion implantation fixation processes can be realized.

In the above embodiment, an example in which nickel was used as the cylindrical electrode material was explained, but the material is not limited to this, and sputtering can be performed using nickel, lanthanum alloy, lanthanum, copper, copper alloy, gold, silver, aluminum, aluminum alloy, etc. Any metal that is easy to bond can be applied to the present invention.

In addition, as an example of the gas to be processed, the ionization treatment of Kr-85 gas has been described (although the present invention is applicable to other radioactive gases,
The present invention also applies to toxic gases, and the ionization chamber is not limited to three divisions.

Note that the cooling medium is not limited to water, and the high voltage applied between the cylindrical electrode and the container naturally varies depending on the size of the container and the electrode, and is not limited to 2 to 5 kV. Furthermore, the pressure of the gas introduced into the container is not limited to the values described above.

[Effects of the invention] As explained above, according to the radioactive gas immobilization processing device of the present invention, radioactive gas recovered at a fuel reprocessing plant,
For example, the ion implantation and immobilization processing capacity can be adjusted by adjusting the amount of Kr-85 gas, so that an online ion implantation and immobilization processing apparatus can be operated continuously.

Therefore, it is not necessary to repeatedly start and stop the device, the maintenance of the device is easy, the power consumption is low, and it is possible to save labor, which has great practical effects.

[Brief explanation of drawings]

1 to 3 are vertical sectional views showing first to third embodiments of a radioactive gas immobilization device according to the present invention, and FIG. 4 is an outline of a conventional injection device for ionizing and injecting radioactive gas. FIGS. 5 and 6 are cross-sectional views of the apparatus shown in FIG. 1. 1・・・・・・・・・・・・・・・・・・・・・Cylindrical container 3・・・・・・・・・・・・・・・・・・・・・Cooling pipe 6 .23.24... Insulator 8.10... Valve 9.11...
・・・・・・・・・Pipe 12・・・・・・・・・
.........Cooling pipe 14...
・・・・・・・・・・・・Ionic layer 20.21.2
2...Cylindrical electrode 25.26.27...Lead wire 28.29.30...Switch 31...High voltage Power supply 32.331.34...Patent attorney for ionized seedlings Sasa Suyama - Figure 1 Figure 2 Figure 3 Figure q Figure 5 Figure S

Claims (3)

[Claims] (1) A cylindrical container into which a radioactive gas to be treated is introduced, an electrode placed inside this container, a DC voltage power source that applies a high voltage of different polarity between this electrode and the container, and a DC voltage power supply inside the container. 1. A radioactive gas immobilization processing device comprising a plurality of ionization chambers electrically insulated and divided into a plurality of ionization chambers. (2) The radioactive gas immobilization process according to claim 1, wherein the electrode is a hollow cylindrical body that is divided into a plurality of parts via an insulator and is provided with a cooling pipe. Device. (3) The distance between the container and the electrode is 2 to 5 k depending on the power source.
A high voltage of V is applied, a negative voltage of 2 to 5 kV is applied to the electrode, and a negative voltage of 2 to 5 kV is applied to the container to coat the inner surface of the container with an ionized layer and sputtered ions. 2. The radioactive gas immobilization processing apparatus according to claim 1, wherein the layers are alternately accumulated.