JPH04248500A - Fixation treatment device of radioactive gas - Google Patents

Abstract

PURPOSE:To obtain a safe, economic and highly reliable fixation treatment device of radioactive gas by making handling works of the treatment device itself that becomes a radiation source after fixation treatment of the radioactive gas, to be of much safer and easier one, at the same time, by enabling effective heat removal of ion injection electrodes during fixation treatment operation and of decay heat during storage period, respectively. CONSTITUTION:A treatment device itself 60 is arranged in an upwardly opening shielded vessel 70 that is shielding radiation, as well as penetrating grooves 90 through which pipings.wirings 61 from the treatment device itself pass through are formed at an end surface of the opening of the shielded vessel, slantly to straightly progressing direction of radiation which is generated from the treatment device itself, and finally a shielding lid 80 is put on an end part of the opening of the shielded vessel in order to cover whole circumference of the treatment device itself 60 with shielding bodies 70 and 80.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a radioactive gas immobilization processing device that ionizes radioactive gas generated in a nuclear fuel reprocessing plant, etc., and injects the gas ions into a metal structure for immobilization. The present invention relates to a radioactive gas immobilization processing apparatus that facilitates handling of the processing apparatus body after the immobilization processing operation is completed.

0002

[Prior Art] In nuclear facilities such as nuclear fuel reprocessing plants, if a harmful amount of radioactivity is released into the environment, the effects may be wide-ranging and long-lasting, compared to other general industries. There is a strict obligation to ensure safety. For example, in a nuclear fuel reprocessing plant that recovers uranium and plutonium from spent nuclear fuel, radioactive gases containing fission products are generated during the spent nuclear fuel shearing and melting processes. Of these, the radioactive gas that is most likely to cause problems is krypton-85 (hereinafter abbreviated as Kr-85), which has a half-life of approximately 10
．． Seven years is a very long time, so efforts are being made to develop technology that will allow it to be stored safely for a long period of time.

[0003] The radioactive gas storage methods that have been developed to date include the high-pressure cylinder storage method in which the radioactive gas is stored in a pressure container such as a high-pressure cylinder, and the Kr-8 storage method.
Generally known methods include a zeolite adsorption method in which 5 is adsorbed on zeolite, an ion implantation method in which a radioactive gas is ionized and injected into the metal structure, and the like.

[0004] However, in the high-pressure cylinder storage method, since it is mandatory to periodically conduct a pressure test of the storage container storing the radioactive gas, it is necessary to transfer the stored gas to a different container each time. Requires complicated work. Furthermore, since the zeolite adsorption method requires processing of Kr-85 at high temperature and high pressure, there are many problems before it can be put to practical use. On the other hand, ion implantation method
Since treatment can be performed at room temperature and low pressure, it can be said to be advantageous in terms of economy and stability compared to the above-mentioned high-pressure cylinder storage method and zeolite adsorption method.

FIG. 6 is a sectional view showing a conventional general radioactive gas immobilization processing apparatus that immobilizes radioactive gas by the above-mentioned ion implantation method.

In the figure, reference numeral 1 denotes a solidification container with a closed structure for immobilizing radioactive gas, and this immobilization container 1 has the following features:
A cylindrical ion implantation electrode 2, an anode bottom 4 connected to the lower part of the ion implantation electrode 2 through a ring-shaped insulator 3a, and an anode bottom 4 connected to the upper part of the ion implantation electrode 2 through an insulator 3b. The anode flange 5 is composed of an anode flange 5 for connection, and an anode cover 6 which is tightened and fixed to the upper surface of the anode flange 5 with bolts and nuts (not shown).

The anode cover 6 has an intake pipe 7 and an exhaust pipe 8.
is connected, and radioactive gas is introduced into the immobilization container 1 through the intake pipe 7 using a vacuum pump (not shown) connected to the exhaust pipe 8. A cylindrical sputter electrode 9 is provided in the immobilization container 1, and a voltage of 1 KV or more is applied to the sputter electrode 9 from a sputter power source 10.
Further, from the ion implantation power supply 11 to the ion implantation electrode 2,
The radioactive gas introduced into the immobilization container 1 is immobilized by applying a voltage of KV or less to each of them.

A water-cooled tube 12 is connected to the upper part of the sputtering electrode 9 through an insulator 13 having a hermetic seal provided in the central opening of the anode cover 6.

In the radioactive gas immobilization processing apparatus configured as described above, immobilization occurs when the gas pressure in the immobilization container 1 and the voltage applied to the ion implantation electrode 2 and the sputtering electrode 9 satisfy appropriate conditions. It is known that a glow discharge occurs within the container 1 and that the radioactive gas within the immobilization container 1 is ionized by this glow discharge.

For example, the gas pressure inside the immobilization container 1 is set to 10
When a voltage of 1 KV or less is continuously applied to the ion implantation electrode 2 and a voltage of 1 KV or more to the sputtering electrode 9 while maintaining the setting at -1 to 10-3 Torr, the radioactive gas in the immobilization container 1 glows. The gas is ionized by the discharge, becomes gas ions 14, is accelerated toward the sputter electrode 9, and collides with the surface of the sputter electrode 9, as shown in FIG. At this time, the sputtered metal 1 is transferred from the sputtered electrode 9.
5 fly out and collide with the surface of the opposing ion implantation electrode 2 to form a metal accumulation layer 16. Further, some of the gas ions 14 are accelerated toward the ion implantation electrode 2 and injected into the metal accumulation layer 16 formed on the surface of the ion implantation electrode 2, as shown in FIG.

[0011] Therefore, by performing such operations until the radioactive gas in the immobilization container 1 is exhausted, Kr-
A radioactive gas such as Kr-85 can be injected and fixed into the metal cumulative layer 16 of the sputtered metal 15 formed on the surface of the ion implantation electrode 2, making it possible to safely store Kr-85 for a long period of time.

[0012] Furthermore, when the radioactive gas is immobilized in the immobilization container 1, the ion implantation electrode 2 generates heat, so it is necessary to effectively remove this heat and maintain constant temperature conditions at all times. For this reason, as shown in FIG. 6, a water cooling tank 17 is provided outside the ion implantation electrode 2 to efficiently cool the ion implantation electrode 2.

By the way, the immobilization container 1 after completing the radioactive gas immobilization treatment operation is separated from the immobilization process line, transported to a storage facility, and stored until the radioactivity level is sufficiently attenuated. . Therefore, handling work of the immobilization container 1 from the end of the radioactive gas immobilization treatment operation to storage and storage (such as separation from the process line, transportation work, container storage work, etc.) is carried out on the immobilization container 1.
Because it itself has a high level of radioactivity, it was thought that it could be carried out using remote work equipment such as manipulators.

[0014]

[Problems to be Solved by the Invention] However, when handling the immobilization container 1 using a remote control device such as a manipulator as in the past, a huge amount of equipment is required and it is difficult to realize this method.

Furthermore, when storing the immobilization container 1 after the immobilization treatment, the cooling water in the water cooling tank 17 must be drained before storage in order to prevent corrosion of the immobilization container 1. On the other hand, in order to stably confine radioactive gas within the metal accumulation layer 16 for a long period of time, it is necessary to maintain a state in which the decay heat of the radioactive gas released from the metal accumulation layer 16 during storage can be removed. There is.

However, if the immobilization container 1 is stored with the cooling water removed from the water cooling tank 17 provided outside the ion implantation electrode 2, the ion implantation electrode on which the metal cumulative layer 16 is formed will A gap is formed between the water cooling tank 2 and the atmosphere, and the inside of the water cooling tank 17 becomes a heat insulating layer. For this reason, the decay heat of the radioactive gas released from the metal accumulation layer 16 during storage cannot be efficiently removed, and the radioactive gas flows into the immobilization container 1 due to the temperature rise of the metal accumulation layer 16 due to the decay heat. There is a possibility of release, which is not desirable from a safety standpoint. In addition, in order to remove the decay heat, it is necessary to separately attach a forced cooling device such as a Freon gas cooling device to the immobilization container 1, which is also economically undesirable.

The present invention has been developed in view of the above points, and makes it possible to safely and easily handle the main body of the processing apparatus that is a radiation source after immobilization of radioactive gas, and to improve the immobilization process. Sometimes ion implantation electrodes,
It is an object of the present invention to provide a radioactive gas fixation processing device that can efficiently remove decay heat during storage and is therefore safe, economical, and highly reliable.

[0018]

[Means for Solving the Problems] In order to achieve the above object, the present invention introduces a radioactive gas into an immobilization container having a closed structure, and introduces a radioactive gas into an ion implantation electrode and a sputtering electrode provided in the immobilization container. A high voltage is applied to generate a glow discharge, the radioactive gas is ionized by the glow discharge, and the gas ions are injected and fixed into a metal cumulative layer of sputtered metal formed on the surface of the ion implantation electrode. In a radioactive gas immobilization processing device, the processing device main body is disposed in a radiation-shielding shielding container that opens upward, and a through hole is provided for passing piping and wiring from the processing device main body through the open end surface of the shielding container. A groove is formed to be inclined with respect to the straight direction of radiation generated from the processing device main body, and a shielding lid is placed over the open end of the shielding container to cover the entire periphery of the processing device main body with a shielding body. be.

[0019]

[Operation] According to the present invention configured as described above, the entire periphery of the processing equipment body is surrounded by the shielding body (the shielding container and the shielding lid), and by removing the shielding lid, only the processing equipment main body can be removed from the shielding container. It can be taken out and stored in a rack or the like in a storage facility. Moreover, the piping and wiring from the processing equipment main body extend to the outside through a through groove formed on the open end surface of the shielding container at an angle with respect to the straight direction of radiation generated from the processing equipment main body. In addition to preventing leakage of radioactivity from the through groove, the shielding container and the processing device main body can be easily separated when the processing device main body is taken out from the shielding container. As a result, the main body of the processing equipment can be handled remotely using the shielding container and shielding lid, so the main body of the processing equipment, which is a high radiation source, can be handled safely and the radiation exposure dose of workers can be reduced. can be significantly reduced.

[0020]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same parts as those shown in FIG. 6 are given the same reference numerals, and the explanation of the parts will be omitted.

FIG. 1 is a longitudinal sectional front view of the entire radioactive gas fixation processing apparatus showing one embodiment of the present invention, FIG. 2 is a plan view of the through groove viewed from above with the shielding cover removed, and FIG. 4 shows a main part of a front view of the through groove viewed from the front, and FIG. 4 shows a plan view of FIG. 1, respectively.

In FIG. 1, a radioactive gas immobilization processing device 50 according to the present invention includes a processing device main body 60 configured to immobilize radioactive gas, and a processing device main body 60 configured to immobilize radioactive gas, and a processing device main body 60 for shielding radioactivity from the processing device main body 60. Mainly composed of a shielding container 70 that is open upward and houses the container body 60 therein, and a shielding lid 80 that closes and shields the upper opening end of the shielding container 70 that houses the processing device body 60 therein. has been done.

Further, the shielding container 70 is constructed such that its height is sufficiently higher than the height of the processing apparatus main body 60, and the opening end surface thereof has a height that is sufficiently higher than that of the processing apparatus main body 60.
A plurality of through grooves 90 are provided radially for drawing out a plurality of pipes/wirings 61 extending from the shielding container 70 to the outside of the shielding container 70.

As a result, the through groove 90 provided in the opening end surface of the shielding container 70 is inclined with respect to the straight direction of radiation generated from the processing device main body 60, and the radioactivity from the through groove 90 is prevented. In addition to preventing leakage, when taking out the processing device main body 60 from the shielding container 70,
0 and the processing device main body 60 can be easily separated.

The processing apparatus main body 60 is constructed almost in the same way as the conventional radioactive gas immobilization processing apparatus shown in FIG. , water-cooled pipe 12, and piping/wiring 61 such as cables for sputtering power source 10 and ion implantation power source 11 are configured to stand upward. Further, a lifting tool 62 for lifting the processing apparatus main body 60 is provided, and a guide plate 63 is attached that serves as a guide for smoothly loading the processing apparatus main body 60 into the shielding container 70. .

The shielding container 70 is made of lead whose outer surface is surrounded by stainless steel to protect it from radiation from the processing apparatus main body 60. A guide rod 71 guided by the guide plate 63 is attached to the inside of the shielding container 70 in order to smoothly move the processing device main body 60 in and out, and a hanging ear for transportation is attached to the outside of the shielding container 70. 72 is installed and at the lower end the foundation bolt 73
is fixed to the foundation via.

A radially extending through groove 90 as described above is cut in the upper opening end surface of the shielding container 70, and the piping/wiring 61 from the processing apparatus main body 60 extends to the outside through this through groove 90. It is connected to external piping and wiring via a pipe joint 64, etc., but as shown in FIGS. 91 is packed.

1 and 4 on the upper surface of the shielding lid 80.
As shown in the figure, hanging ears 81 for installation are attached. Further, the shielding lid 80 is fixed to the upper open end of the shielding container 70 with bolts 82. Here, in order to align the shielding lid 80 and the shielding container 70, the shielding lid 80 is provided with a guide hole 83 through which the guide rod 71 from the shielding container 70 passes.

In order to prevent leakage of radiation from the processing device main body 60, that is, streaming, the above embodiment shows an example in which radial through grooves 90 are provided, but as shown in FIG. Alternatively, a penetrating groove 90a bent at right angles in a hook shape may be provided on the upper opening end surface of the shielding container 70.

Next, remote handling of the processing apparatus main body 60, which has become a high radiation source, will be explained.

Even if the processing device main body 60 becomes a high radiation source, the entire outer periphery of the processing device main body 60 is surrounded by a shielding body consisting of a shielding container 70 and a shielding lid 80, so that radiation will not leak to the outside. Very few. Moreover, the processing device main body 6
The piping/wiring 61 from 0 is the upper end opening surface of the shielding container 70,
That is, it deviates from the center of the processing device main body 60 and penetrates to the outside through a through groove 90, and furthermore, lead hair 91 is packed between the through groove 90 and the piping/wiring 61, so that this Radiation leakage through the through groove 90 is also extremely small.

Therefore, the shielding container 70 of the processing apparatus main body 60
Removal is performed as follows.

First, when the processing device main body 60 is housed in the shielding body (the shielding container 70 and the shielding lid 80), the amount of radiation leaking to the outside of the shielding body is extremely low, so the operator should not approach the shielding body. can do. Therefore, the shielding container 70
The piping/wiring 61 coming out to the outside is separated from the external piping/wiring by removing the pipe joint 64, and further, the bolts 82 fixing the shielding lid 80 are removed.

Next, the shielding lid 80 is lifted via the hanging ears 81 by remote control using an overhead crane, and the processing apparatus main body 60 is further lifted via the lifting tool 62, thereby shielding the processing apparatus main body 60. It can be separated from the container 70.

Here, piping/wiring 6 is connected to the processing device main body 60.
1 is connected, this piping/wiring 61 is inserted into the through groove 90 provided on the open end surface of the shielding container 70, so by lifting the piping/wiring 61 upward, this piping/wiring 61 can be removed. The wiring 61 can be easily separated from the shielding container 70. Then, the processing apparatus main body 60 removed from the shielding container 70 is transported to the storage by an overhead crane.

In other words, the processing device main body 6 has become a high radiation source.
0 in the shielding container 70 and covering the opening with the shielding lid 80, and furthermore, the piping/wiring 61 from the processing apparatus main body 60 is inserted into the through groove 90 provided on the upper opening end surface of the shielding container 70. This prevents radiation from going straight from the processing equipment main body 60, and by passing the piping/wiring 61 from the processing equipment main body 60 through the through groove 90, the piping/wiring 61 can be freely attached to and detached from the shielding container 70. Can be installed on. As a result, the processing device main body 6
0 is a high radiation source, the worker can easily approach the shielding container 70 and easily take out the piping/wiring 61 from the processing equipment main body 60 from the shielding container 70. 60 can be easily separated from the shielding container 70 and the processing apparatus main body 60 can be stored alone.

[0037]

[Effects of the Invention] As explained above, according to the present invention,
The immobilization container after immobilization of radioactive gas can be easily handled, and the ion implantation electrode can be removed during immobilization treatment, and the decay heat can be efficiently removed during storage, making it safe, economical, and reliable. It can be made into a highly radioactive gas fixation processing device. Moreover, by using the shielding container, the shielding lid, and the through groove, the processing equipment main body, which has become a high radiation source, can be safely and easily separated from the shielding container, so the processing equipment main body can be stored independently, and the processing equipment Maintenance and inspection of the main body can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is an overall longitudinal sectional front view of a radioactive gas fixation processing apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of the through groove viewed from above with the shielding lid removed.

FIG. 3 is a main part of a front view of the through groove viewed from the front.

FIG. 4 is a plan view of FIG. 1.

FIG. 5 is a plan view of a shielding container showing another example of a through groove.

FIG. 6 is a longitudinal sectional front view of a conventional radioactive gas fixation processing apparatus.

FIG. 7 is a cross-sectional view illustrating the operation of the radioactive gas fixation processing device.

FIG. 8 is a cross-sectional view illustrating the operation of the radioactive gas fixation processing device.

[Explanation of symbols]

1 Immobilization container 2 Ion implantation electrode 4 Anode bottom 9 Sputter electrode 14 Gas ions 15 Sputtered metal 16 Metal cumulative layer 50 Radioactive gas fixation processing equipment 60 Processing equipment main body 61 Piping/wiring 70 Shielding container (shielding body) 80 Shielding lid (shielding body) 90, 90a Penetration groove 91 Lead hair

Claims (1)

[Claims] 1. A radioactive gas is introduced into an immobilization container having a sealed structure, and a high voltage is applied to an ion implantation electrode and a sputtering electrode provided in the immobilization container to generate a glow discharge. In a radioactive gas immobilization processing apparatus, the gas ions are ionized by glow discharge and injected and fixed into a metal cumulative layer of sputtered metal formed on the surface of the ion implantation electrode. The opening is placed in a shielding container that shields radiation, and a through groove is provided in the open end surface of the shielding container through which piping and wiring from the processing device main body passes, in a direction in which the radiation generated from the processing device main body travels straight. 1. A radioactive gas fixation treatment device, characterized in that the treatment device body is formed to be tilted, and a shielding lid is placed over the open end of the shielding container to cover the entire periphery of the processing device body with a shielding body.