JP2002214392A - Glass solidified body storing facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of primary radiation while securing flow of cooling air in a cell room. SOLUTION: In a glass solidified body storing facility in which glass solidified bodies 1 are stored in the cell room 3 and the cooling air 12 is made to flow, two radiation shielding plates 19 having a desired number of through holes 20 with shifted phases are arranged with a desired interval in the flowing direction of the cooling air 12 in an inlet 13 and an outlet 14 of the cooling air in the cell room 3. The radiation shielding plates 19 have a sandwich structure of two front and back iron plates for attenuating γ rays and a polyethylene plate for attenuating neutron rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vitrified storage facility for storing and managing a vitrified radioactive waste.

[0002]

2. Description of the Related Art Radioactive waste discharged from a nuclear power plant is a vitrified material obtained by vitrifying so as to be contained in a crystal of glass. They must be strictly stored and managed in storage areas for long periods of time.

[0003] FIG. 8 shows an example of a storage facility for a vitrified body that has been conventionally proposed for storing a vitrified body obtained by vitrifying the above-mentioned radioactive waste for a long period of time. . That is, a cell room (storage pit) 3 surrounded by a thick concrete shielding wall as a storage area for the vitrified body 1 is constructed immediately below the transfer chamber 2 for handling the vitrified body 1 using a crane. A large number of cylindrical storage tubes 4 for storing the vitrified body 1 inside the cell chamber 3 are supported by being suspended at required intervals from a ceiling slab 5 with an open upper end. When a large number of vitrified bodies 1 are stored in a stacked state from above in the inside of each storage tube 4, the storage tube plug 6 is placed in the upper end portion of each storage tube 4.
The vitrified body 1 is sealed in the storage tube 4 by closing the upper end opening with the storage tube lid 7, and an outer cylinder 8 is arranged around the storage tube 4. To form a cylindrical flow path 9 between the storage pipe 4 and the cylindrical flow path 9.
Upper and lower plenum sections 10 and 11 are respectively defined above and below the lower plenum section 11.
One end of the upper plenum section 10 has an inlet 13 for cooling air 12, and one end of the upper plenum section 10 has an outlet 14 for cooling air 12.
Are provided as vents, and the cooling air inlet 13 communicates with the intake passage 15, and the cooling air outlet 14 communicates with the exhaust tower 16.
The cooling air 12 taken into the lower plenum section 11 through 3 is sent into the cylindrical flow path 9 and is moved into the upper plenum section 10.
The vitrified body 1 in the storage tube 4 is cooled by natural air cooling by being discharged through the outlet 14 and the exhaust tower 16.

[0004]

However, in such a vitrified storage facility, mainly in order to cool the heat generated from the vitrified body 1, the cell space 3 is ventilated to secure the flow of the cooling air 12. A cooling air inlet 13 and an outlet 14 are provided as ports.
In order to prevent radiation from leaking, the upper end of the intake passage 15 communicating with the cooling air inlet 13 and the upper end of the exhaust tower 16 communicating with the cooling air outlet 14 are set at a high position. Shielding measures such as increasing the wall thickness on the outside of the cell chamber 3 facing 14 are taken.

Accordingly, the present invention is to reduce the wall thickness of the facility by efficiently attenuating the main radiation while securing the flow of the cooling air in the cell chamber. It is intended to lower the upper end position of the exhaust tower.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vitrified cell storage facility in which a vitrified body is stored in a concrete cell chamber and cooling air flows. A plurality of radiation shielding plates are arranged side by side so as to overlap at a required interval in a flow direction of the cooling air in a ventilation opening serving as a cooling air inlet / outlet. The ventilation passage for circulation is provided so that the phase is shifted between adjacent radiation shielding plates.

Since the cooling air can pass through the ventilation passage of the radiation shielding plate, the circulation of the cooling air in the cell chamber is ensured. The radiation is shielded by the upstream radiation shielding plate, and the radiation passing through the ventilation passage is shielded by the downstream radiation shielding plate.

Further, the radiation shielding plate has a sandwich structure of two front and rear iron plates and a polyethylene plate disposed between the two iron plates, so that the γ-rays can be irradiated by the neutron beam by the front iron plate. Can be attenuated by the polyethylene plate, and the secondary radiation generated by the interaction between the neutrons and the polyethylene plate can be shielded by the iron plate on the rear side.

Further, by making the radiation shielding plate disassemblable, it is possible to easily replace the polyethylene plate.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the present invention. In a vitrified storage facility having the same structure as that shown in FIG. 8, a cooling air inlet 13 serving as a vent of a cell chamber 3 is provided. In the outlet 14, two sandwiched structures of two front and rear iron plates 17 for attenuating γ-rays and a polyethylene plate 18 for attenuating a neutron beam disposed between the two iron plates 17 are provided. The radiation shielding plates 19 are arranged side by side so as to overlap with each other at a required interval in the flow direction of the cooling air 12, and a ventilation flow for flowing the cooling air 12 in a thickness direction at a required portion of each radiation shielding plate 19. The through holes 20 as paths are provided so that the phases are shifted between two adjacent radiation shielding plates 19.

As shown in detail in FIGS. 2 to 4, the radiation shielding plate 19 is made of two pieces of carbon steel, stainless steel, or the like, which are thickly edged so that only the peripheral portion 17a protrudes toward one side. The iron plate 17 is arranged so that the thickened peripheral portions 17a face each other, and a size corresponding to the size of the space formed by the two iron plates 17 overlapped between the two iron plates 17. And a sandwich structure in which a polyethylene plate 18 is sandwiched between the two iron plates 17.
7a, a plurality of pin holes 2 formed in the peripheral portion 17a.
1 is configured so as to be disassembled by inserting a fixing pin 22 therethrough. Furthermore, each radiation shielding plate 19 has
A through-hole 20 penetrating through the three plates of the iron plate 17, the polyethylene plate 18, and the iron plate 17 so that the phases are shifted from each other.
Are provided in the thickness direction as ventilation passages for the cooling air 12.

As shown in detail in FIGS. 4 and 5, the fixing pin 22 has a flange 22a at a base end, and a pin hole 21 of a peripheral portion 17a of two superposed iron plates 17 from a pin hole 21 to a tip portion 22b. A protruding length;
b is configured to be bendable by a hinge 23, and two iron plates 1
7, the two iron plates 17 are fixed by bending the distal end portion 22b sideways at right angles.

In the vitrified storage facility having such a configuration, a radiation shielding plate 19 having air permeability is arranged in the cooling air inlet 13 and the cooling air outlet 14 of the cell chamber 3 in the direction of flow of the cooling air 12. Accordingly, it is possible to prevent the radiation from leaking out of the cell chamber 3 while ensuring the fluidity of the cooling air 12.

More specifically, for example, as shown in FIGS. 1 and 2, when the cooling air outlet 14 of the cell chamber 3 is viewed, two radiation shielding plates 19 arranged in the flow direction of the cooling air 12 are formed. Since a required number of through holes 20 are provided in the thickness direction, the cooling air 12 can pass through these through holes 20. Therefore, the flowability of the cooling air 12 in the cell chamber 3 can be ensured, and heat is cooled.

Each of the through holes 20 is provided with two radiation shielding plates 19 arranged in parallel in the flow direction of the cooling air 12.
Are out of phase with each other, so that the radiation
Even through the through-hole 20 of the radiation shielding plate 19 located on the upstream side in the flow direction 2, the radiation shielding plate 19 located on the downstream side will shield the radiation. In this case, the radiation generated from the radioactive waste is mainly γ-rays and neutron rays, and the γ-rays are effectively attenuated by hitting the iron plate 17 on the front side of the sandwiched radiation shielding plate 19. On the other hand, a neutron beam can be attenuated by the polyethylene plate 18. At this time, when the neutron beam is extinguished by the interaction with the polyethylene, secondary radiation (usually secondary γ-ray) is emitted, and this secondary radiation is emitted by the iron plate 17 on the rear side. Be shielded. In the above case, the high-energy neutron beam is quickly reduced to medium energy by the iron plate 17,
By having the structure in which the polyethylene plate 18 is sandwiched between the two iron plates 17, neutron shielding performance per unit thickness can be improved as compared with the case where the shielding material is used alone. Therefore, as shown in FIG.
The thickness of the outer wall of the cell chamber 3 facing the fuel cell 4 can be reduced, and the upper end positions of the intake passage 15 and the exhaust tower 16 can be set low.

In the above, when the polyethylene plate 18 has deteriorated with time, the distal end portion 22b of the fixing pin 22, which stops the peripheral portion 17a of the two iron plates 17, is returned from the bent state to the linear state. Since the iron plate 17 on the side can be removed, the polyethylene plate 18 can be easily replaced.

FIGS. 6 and 7 show another embodiment of the present invention. In a configuration similar to that shown in FIGS. 1 to 5, two radiation shielding plates 19 are used as ventilation passages. Instead of providing the through holes 20, two radiation shielding plates 1
At the upper end side and the lower end side of 9, notches 24 penetrating in the thickness direction so as to be out of phase with each other are provided in a staggered manner in the width direction. Other configurations are the same as those shown in FIGS. 1 to 5, and the same portions are denoted by the same reference numerals.

The configuration shown in FIGS. 6 and 7 can provide the same operation and effects as those of the embodiment shown in FIGS.

In the above embodiment, two radiation shielding plates 19 are arranged at the cooling air inlet 13 and the cooling air inlet 14 of the cell chamber 3, respectively. However, three or more radiation shielding plates 19 may be provided. It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0021]

As described above, according to the vitrified material storage facility of the present invention, the above-mentioned cell in the vitrified material storage facility in which the vitrified material is stored in the concrete cell chamber and the cooling air is caused to flow therethrough. A plurality of radiation shielding plates are arranged side by side so as to overlap at a required interval in a flow direction of the cooling air, in a ventilation opening serving as a cooling air inlet / outlet of the chamber,
In addition, ventilation passages for circulating cooling air are provided at required positions of the respective radiation shielding plates so that adjacent radiation shielding plates are out of phase with each other. The cooling air can pass through the ventilation flow path of the radiation shielding plate because of the sandwiched structure of the iron plate and the polyethylene plate disposed between the two iron plates. Radiation can be ensured, and radiation can be reliably shielded by a plurality of radiation shielding plates. At this time, the main radiation γ-rays are attenuated by the iron plate in front of the radiation shielding plates Neutron beam can be attenuated by the polyethylene plate, and the secondary products released by the interaction between the neutron and the polyethylene plate Radiation can be shielded by the iron plate on the rear side, so that the outer wall thickness of the cell chamber facing the vent can be reduced, and the upper end position of the intake passage and the exhaust tower communicating with the vent can be reduced. It is possible to set a low value, and furthermore, by adopting a configuration in which the radiation shielding plate can be disassembled, excellent effects such as easy replacement of the polyethylene plate are exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a vitrified material storage facility of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a view taken in the direction of arrows BB in FIG. 2;

FIG. 4 is a perspective view of a radiation shielding plate.

FIG. 5 is an enlarged view of a portion C in FIG. 4;

6 shows another embodiment of the present invention, and is an enlarged view corresponding to a portion A in FIG. 1. FIG.

FIG. 7 is a view in the direction of arrows DD in FIG. 6;

FIG. 8 is a schematic view showing an example of a vitrified storage facility.

[Explanation of symbols]

 3 Cell Room 12 Cooling Air 13 Cooling Air Inlet (Vent) 14 Cooling Air Outlet (Vent) 17 Iron Plate 18 Polyethylene Plate 19 Radiation Shielding Plate 20 Through Hole (Vent Flow Channel) 24 Notch (Vent Flow Channel)

Claims (3)

[Claims] 1. A plurality of radiation shielding plates are provided in an air vent serving as a cooling air inlet / outlet of said cell room in a vitrified material storage facility in which a vitrified material is stored in a concrete cell room to flow cooling air. Are arranged side by side so as to overlap at a required interval in the flow direction of the cooling air, and at a required position of each radiation shielding plate, a ventilation flow path for flowing cooling air is formed between adjacent radiation shielding plates. A vitrified material storage facility having a configuration provided so as to be out of phase with each other. 2. A radiation shielding plate comprising: two front and rear iron plates;
The vitrified material storage facility according to claim 1, wherein the vitrified material storage facility has a sandwich structure with a polyethylene plate disposed between two iron plates. 3. The radiation shielding plate can be disassembled.
A vitrified storage facility as described.