JPH0658436B2 - Pneumatic transportation method for radioactive waste - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for pneumatically transporting a powder or granular material containing a radioactive substance such as radioactive waste.

2. Description of the Related Art In the suction type pneumatic transportation method adopted in the general industry, as shown in FIG. 2, the granular material supplied to the storage hopper (1) is cut out by the rotary valve (2) and the suction port is The air sucked from (3) transports the inside of the pipeline, and the cyclone (4) and the bag filter (5) separate the powder and granules from the air. Rotary valve for separated powder
The air cut out by (6) and (7) is fed into the collection hopper (8), while the air from which the particulates have been removed is released from the blower (9) into the atmosphere. The air flow rate is adjusted manually or automatically by the valve (10). When radioactive waste (such as radioactive incineration ash) is transported by such a method, trace amounts of radioactive substances are still mixed in the air that exits the bag filter (5), which may be harmful to the atmosphere. However, this can be solved by providing a HEPA filter (fine particle removal filter) (not shown) downstream of the bag filter (5).

Problems to be Solved by the Invention By the way, the air used for pneumatic transportation of radioactive materials is
Even after passing through the HEPA filter, it must be released to the atmosphere via the stack after confirming that the amount of radioactive material is below the specified value with a radiation measurement device. It is desirable that the number is as small as possible. However, according to the above-mentioned conventional method, there is a problem in that the reduction of the air amount is restricted in consideration of the transportation capacity. Also, while the blower (9) is in operation, it is possible to maintain a negative pressure inside the pipeline, but due to the low support, atmospheric pressure inside the pipeline causes the radioactive material remaining in the pipeline to leak out of the pipeline. There is.

An object of the present invention is to solve the above problems and to circulate and use air with a pipe line as a closed pipe line,
The inside of the pipeline is always kept in a negative pressure state.

Means for Solving the Problems In order to solve the above problems, a method for pneumatically transporting radioactive waste or the like according to the present invention provides a transportation pipeline for pneumatically transporting a granular material containing a radioactive substance. An exhaust pipe line for keeping a negative pressure inside is always connected, and in the transport pipe line, the granular material supplied into the storage hopper is fed to the separating means by air, and the separating means forms the powder particles. The body is separated from the air and sent into the collection hopper, and the air from which the particulates have been removed is returned to the storage hopper by the transport blower and circulates, and the exhaust blower is circulated in the exhaust pipe line. Constantly discharge a part of the air from which the powder and granules have been removed into the atmosphere through a filtering means, so that the inside of the transportation pipeline is always kept in a negative pressure state. .

Action In the above configuration of the present invention, since air is circulated and used in the transportation pipeline, there is no air released from the transportation pipeline to the atmosphere, and a portion of the clean air is slightly discharged from the exhaust pipeline. It is only released into the atmosphere. Further, since the inside of the transportation pipeline is always kept in a negative pressure state, radioactive substances in the transportation pipeline do not leak out of the pipeline.

Embodiment One embodiment of the present invention will be described below with reference to FIG.
FIG. 1 is a system diagram of an air transportation device (11) to which the air transportation method of this embodiment is applied.

The air transportation device (11) is formed by connecting the exhaust pipeline (13) to the transportation pipeline (12). In the transportation pipeline (12), the storage hopper (1
4), the separating means (15), the valve (16) and the transport blower (17) are connected so as to form a closed pipe. Storage hopper (1
The rotary valve (18) is installed in 4). The separating means (15) is composed of a cyclone (19) and a bag filter (20) connected in series. Cyclone (19) and Bagfilter (20)
And are the rotary valves (21), (2
It is connected to the collection hopper (23) via 2). A pressure controller (24) is connected to the bag filter (20) branched from the downstream side of the bag filter (20) to control the opening of the valve (16). In the exhaust pipe line (13), branch from the downstream of the transport blower (17) to obtain a filtering means.
The valve (25), the valve (26) and the exhaust blower (27) are connected to each other in series, and the pressure regulator (28) is connected. A HEPA filter or the like is suitable for the filtration means (25). The pressure regulation design (28) controls the opening of the valve (26).

Next, the air transportation method of this embodiment for the air transportation device (11) having the above-mentioned configuration will be described.

The granular material containing the radioactive substance is supplied into the storage hopper (14). First, the exhaust blower (27) is operated, and a part of the air in the transportation pipeline (2) is released into the atmosphere. The pressure regulator (28) detects the pressure in the transport line (2) and
By controlling the opening of (26), the inside of the transportation pipeline (2) is maintained at an appropriate negative pressure. When radioactive material is contained in the air to be discharged, it is removed by the filtration means (25).

Next, the transport blower (17) is operated. At this time, the exhaust blower (27) continues to operate. Transport blowers (17)
The pressure on the downstream side (discharging side) rises, the pressure regulator (28) increases the opening of the valve (26), and the discharge amount from the exhaust blower (27) increases. After a certain time, a blower for transportation (17)
The pressure on the downstream side also becomes a negative pressure, and a negative pressure pressure equilibrium state is formed in the transportation pipeline (2). At this time, pressure regulator (24)
Controls the opening of the valve (16) to keep the air flow rate in the transportation pipeline (2) constant. After the pressure equilibrium state and the air flow rate in the transportation pipeline (2) have become constant, the rotary valve (18) cuts out the granular material in the storage hopper (14). The air circulated in the transportation pipeline (2) by the transportation blower (17) sends the powdery particles to the separating means (15). Separation means (1
In 5), the cyclone (19) separates the granular material from the air by centrifugal force and sends only the air to the bag filter (20). The bag filter (20) separates finer particles from the air due to the bag. The powder particles thus separated are cut out by the rotary valves (21) and (22) and fed into the collection hopper (23). On the other hand, the clean air from which the particles have been removed is sucked by the transport blower (17), returned to the storage hopper (14) and circulated.

When the transportation blower (17) is stopped, air flows into the transportation pipeline (2) from the blower (17) and the shaft seals of the rotary valves (18), (21) and (22), In addition, air for backwashing the bag filter (20) is added during operation. However, these increased air amounts are discharged into the atmosphere by the exhaust blower (27) that is constantly operating.

EFFECTS OF THE INVENTION The present invention is configured as described above, but since the inside of the transportation pipeline is always kept in a negative pressure state regardless of whether the transportation blower is stopped or operating, the radioactive material is There is no risk of leakage to the outside of the pipeline, and since the transport pipeline is formed as a closed pipeline, the transport air is circulated and used,
The air released to the outside of the pipeline is 1/1 of that of the conventional open pipeline.
It has an excellent effect such as a significant decrease of 100 or less.

[Brief description of drawings]

FIG. 1 is a system diagram of an air transportation device to which the method of pneumatic transportation of radioactive waste of the present invention is applied, and FIG. 2 is a system diagram showing an example of a conventional air transportation device used in general industry. . (11) …… Pneumatic transport device, (12) …… Transport pipeline, (13) …… Exhaust pipeline, (14) …… Storage hopper, (15) …… Separation means, (17)
...... Transportation blower, (23) …… Collection hopper, (25) …… Filtration means, (27) …… Exhaust blower.

Claims (1)

[Claims] 1. An exhaust pipeline for keeping a negative pressure inside the transport pipeline is connected to a transport pipeline for pneumatically transporting a granular material containing a radioactive substance, and the storage pipeline is provided in the transport pipeline. The powder and granules supplied inside are fed to the separating means by air, and the separating means separates the powder and granules from the air and feeds them into the collecting hopper, and the powder and granules are removed. The air is returned to the storage hopper by the transportation blower and circulates, and in the exhaust pipe line, the exhaust blower constantly discharges a part of the air from which the powder and granules have been removed into the atmosphere through the filtering means. By doing so, the method for pneumatic transportation of radioactive waste, characterized in that the inside of the transportation pipeline is always kept in a negative pressure state.