JPS61100700A - High-level radioactive waste storage tank facility - 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] [Field of Application of the Invention] The present invention relates to a storage tank for high-level radioactive waste generated at a reprocessing plant that reprocesses spent fuel of a nuclear power plant, and particularly relates to a storage tank for high-level radioactive waste produced at a reprocessing plant that reprocesses spent fuel of a nuclear power plant. This invention relates to a storage tank that combines the necessary cooling and shielding of high-level radioactive waste.

[Background of the invention]

Figure 3 shows the structure of a conventional high-level radioactive waste storage tank, with (a) being a cross-sectional view and (b) being (c).
It is a sectional view taken along the line A-A of FIG.

Tank 1 is a tank that holds high-level radioactive waste.
A cooling tip 2 is provided inside to prevent the waste from boiling and evaporating due to heat generation from the waste. The lid 3 of the tank 1 is welded to a radial reinforcement 4. A concrete shielding wall 5 is installed on the outside of the tank 1, and between this shielding wall 5 and the outer wall of the tank 1, the tank 1
A reinforcing ring 6 is installed to reinforce the structure. A drain sump 7 is provided at the bottom of the shielding wall 5 to drain leaked waste and detect leakage when there is leakage from the tank.

The cooling pipe 2 has two independent systems, so that even if one system breaks down, it can be covered by the other system.

This cooling J? Eve 2 is arranged in a coil shape within tank 1. In FIG. 3(a), cooling water is injected into the coiled cooling pizo 2 from above and discharged from below.

The outside of the concrete shielding wall 5 is a large wall 8, and the chamber 8 has an even thicker concrete shielding wall 9.

Various types of radiation are emitted from high-level radioactive waste, but γ
Since almost everything other than rays and neutrons is absorbed by tank 1, most of what comes out of tank 1 are gamma rays and neutrons. In order to shield these, a concrete shielding wall 5 having a thickness of about 1 m is provided. Furthermore, the concrete shielding wall 9 of the chamber 8 is also designed to have a thickness of 1 m or more, ensuring complete shielding.

In addition, although high-level radioactive waste is in a concentrated liquid form, it contains a small amount of solid content.In order to mix this uniformly and prevent solidification and local overheating, air is removed. The air is pumped into the container and mixed with the liquid by bubbling, and this air is removed from the tank with a no-igu, passed through a filter to attenuate the radioactivity, and then released to the outside.
Although there is a device installed, it is not directly related to the present invention and will therefore be omitted here.

As described above, it can be said that the conventional example shown in FIG. 3 takes all possible measures from the viewpoint of reducing radiation exposure, but it has the following drawbacks.

■ Because the cooling pipe system is adopted, if the cooling pipe 2 leaks, cooling water will flow from the cooling A've 2 into the tank 1, the liquid level in the tank 1 will rise, and the waste liquid supply pipe, measurement pipe, etc. There is a possibility that high-level radioactive waste may leak into various pipes from tank 1. Alternatively, there is a possibility that high-level radioactive waste may flow into the cooling A-vehicle 2 from the leakage part and spread contamination.

- Since the upper lid 3 of the tank 1 is made of only a steel plate, it is necessary to make the ceiling wall of the room 8 thicker in order to completely shield the upper part of the tank 1 including the upper floors. The reason why the lid 3 of the tank 1 is made of only a steel plate is that if a concrete shielding wall is placed on the lid 3, it will be difficult to cover the lid 3 during maintenance.
This is because the weight of the door is too heavy, making it impossible to open and close it.

[Purpose of the invention]

The purpose of the present invention is to make the tank shielding structure and cooling system more rational, high-performance, and highly safe.
It is an object of the present invention to provide a high-level radioactive waste storage tank that prevents leakage of radioactive waste and has a large shielding effect at the lid part.

[Summary of the invention]

The present invention aims at simplifying the cooling and shielding structure in a high-level radioactive waste tank by using cooling water and also as an insulation material.

The present invention is characterized by a high-level radioactive waste tank facility comprising a tank for storing high-level radioactive waste, a cooling system for cooling the waste, and a shielding wall for shielding radiation from the waste. The tank and the lid have a double or triple or more layered structure, and water from the cooling system is circulated within the double or triple or more layered structure of the tank. Furthermore, the interior of the double or triple layer structure of the tank and lid is divided into radial or lattice-shaped chambers by reinforcing plates, passages are provided to selectively connect each chamber, and an independent cooling system is connected to the Preferably, cooling water is injected into each chamber separately, and the cooling water flows through each chamber without mixing and is discharged separately.

By allowing water to flow also into the lid in this way, it is possible to improve the shielding performance. Also, when opening and closing the lid, you can drain the water and perform all maintenance.

In addition, a material such as beryllium that converts gamma rays into neutrons is installed in the form of a plate on the inside or outside of the inner wall of a tank with a double or triple-layered structure, such as the tank and lid, to prevent gamma rays from high-level radioactive waste. By converting neutrons into neutrons and then shielding them with water, the required thickness of water shielding can be reduced.

The cooling system has an independent configuration in case of failure, but by connecting them with valves and piping,
It is also possible to deal with failures of pumps, etc.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

Embodiment 1 The tank facility according to the embodiment of the present invention shown in FIG. 1 is installed in the same room 8 as the conventional example shown in FIG. 3, and the part where the tank is removed from the bed is omitted.

FIG. 1(a) is a diagram showing an elevational section of an embodiment of the present invention.
A metal plate 10 is installed on the outer side of the inner wall of the tank for storing high-level radioactive waste, and the outer side thereof is a shielding tank 11 into which water from the cooling system flows.

Inside the shielding tank 11, there are reinforcing plates 12 arranged radially as shown in FIG. A flow path 14 is provided that selectively communicates between chambers 13 partitioned by plates 12.The lid 3 also has the same tank structure.

The cooling water passes through the valve 1st, and a portion further passes through the valve 16 and enters the shield tank 11 of the lid 3 through the 7th lung 17t.
The remaining water flows downward after the valve 15 and flows from the pipe 18 into the shield tank 11 around the tank 1 body.

The cooling water that has entered the shielding tank 11 of the lid 3 passes through the flow path 14 into another chamber 13, and further exits from the pipe 19, passes through the flange 20, passes through the valve 21, and the valve 22.

On the other hand, the cooling water that has flowed into the shielding tank 11 around the main body of the tank 1 passes through the lower flow path 14 into another tank 13, rises up, and exits from the pipe 23 through the valve 22.

Here, if the valve 16 is closed and the valve 24 is opened, the water in the shielding tank 11 of the lid 3 will be discharged to the outside. It can be opened and closed in the same way.

As shown in Figure 1 (b), the cooling system is completely divided into system A and system B, so even if one system fails or breaks, sufficient cooling can be achieved with the other system. . That is, even if the piping of one system is damaged, the cooling water in the tank can be secured by closing the valves 15, 16, 21, 22 of the damaged system. In particular, the cooling water in the lower shielding tank 11 will not leak out even in the event of a sudden large break, probably because the pipes 18 and 23 are installed above.

In addition, in case of a failure of the pump on one side of the cooling system,
By opening the valve 27 of the pipe 26 connecting the system and the B system and closing the valve 15.22 on the faulty side, the inside of the tank 1 can be cooled uniformly.

Embodiment 2 FIG. 2 shows another embodiment of the present invention. (F) is an elevational cross-sectional view, and (B) is (A) an OA-A cross-sectional view. This embodiment is an example in which the outer shielding tank 11 of the tank 1 has a double tank structure. □ In this example, the outer tank and inner tank of the double tank structure are completely separated according to the cooling system. The rest is the same as that of the implementation side light, so the explanation will be omitted.

With this structure, uniform cooling is possible even if there is pipe damage on the tank 1 side from the connecting pipe 26 on one side of the cooling system. In addition, even if there is a pipe breakage on the outside of the connecting pipe 26, open the connecting valve 27, and open the valve 15.2 of the damaged pipe.
By closing 2, uniform single-system operation is possible.

〔Effect of the invention〕

■ By making the outside of the high-level radioactive waste storage tank a shielding tank through which cooling water passes, shielding from water is possible9.The concrete shielding wall outside the tank becomes an annual bond,
Furthermore, coil-shaped cooling 1 inside the storage tank? Since there is no need for an eve, maintenance and maintenance inside the storage tank becomes easier.

■ The water inside the lid can be drained when the lid is opened and closed, making construction and maintenance easier, and the shielding effect of water during normal operation reduces radiation exposure and reduces the wall thickness of the room.

■ IJ, l on the inner or outer side of the storage tank wall.
If a substance that causes a γ-n reaction, such as Jium, is placed, the shielding effect can be improved by taking advantage of the good neutron absorbability of water, so the water shielding tank can be made thinner.

[Brief explanation of drawings]

FIG. 1(f) is an elevational sectional view showing one embodiment of the present invention, and FIG. 1(b) is a sectional view taken along line A-A. FIG. 2(A) is an elevational cross-sectional view showing another embodiment of the present invention, and FIG. 2(B) is a cross-sectional view taken along the line A-A. Figure 3 (a) is an elevational cross-sectional view of the conventional example, and Figure 3 (b)
is a sectional view taken along line A-A. [Explanation of symbols] 1: Storage tank 2: Cooling pipe 3: Lid
4: Reinforcement material 5: Shielding wall 6: Reinforcement ring 7: Drain sump 8: Chamber 9: Shielding wall 10: Perillium plate 11: Shielding tank 12: Reinforcement partition plate 13: Chamber
14: Flow path 15. 16: Valve 17: Flange 18. 19: Piping 20: Flange 21. 22: Valve ゝ° 23
: Piping 24: Valve ゝ゛25: 25 : Hook 26: Piping 27: Valve Figure 1 Figure 2

Claims (1)

[Claims] 1. A tank for storing high-level radioactive waste and its lid are composed of at least double walls, and are provided with means for circulating cooling water in the space between the walls of the tank and the lid. A high-level radioactive waste storage tank facility featuring: 2. The space between the walls of the tank and the lid is divided into radial or lattice-shaped chambers by reinforcing plates, passages are provided to selectively connect each chamber, and each chamber is separately connected to an independent cooling water system. 2. The high-level radioactive waste storage tank facility according to claim 1, wherein cooling water is injected into the chamber, and the cooling water flows through each chamber without mixing and is discharged separately. 3. The high-level radioactive waste storage tank equipment according to claim 1, wherein the tank and the lid have three or more walls, and cooling water is circulated through the space between the walls from independent cooling water systems. 4. High-level radioactivity according to any one of claims 1 to 3, wherein a material such as beryllium that converts gamma rays into neutrons is installed in the form of a plate on the inside or outside of the inner walls of the tank and the lid. Waste storage tank equipment. 5. High-level radioactive waste storage tank equipment according to claim 2 or 3, in which independent cooling systems are connected to each other by valves and piping.