JPH0562318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to exhaust equipment for decommissioning a nuclear reactor.

There is no previous experience in nuclear reactor decommissioning work, and therefore, in order to carry out this decommissioning work safely, it is necessary to configure work equipment from a new perspective. In particular, when thermally cutting activated biological shielding concrete, it is necessary to minimize the radiation exposure of workers due to the generation of radioactive dust and to effectively remove the heat generated during thermal cutting. . It is also necessary to minimize the pollution of the surrounding environment during this decommissioning work.

The present invention aims to provide exhaust equipment for nuclear reactor decommissioning work that satisfies these requirements at the same time.

That is, as shown in the drawing, the present invention is a facility for effectively achieving the above object, in which the decommissioning work area of a nuclear reactor is isolated from the surrounding atmosphere by an airtight material to form a closed space 1. Exhaust equipment used when decommissioning equipment that is driven by remote control is installed in a closed space 1 to perform decommissioning work that involves thermal cutting, and is an exhaust passage that leads from inside the closed space 1 to the outside. 2, a dust collector 3 and a blower 4 are interposed in this exhaust passage 2, and the exhaust passage 2 is branched from the exhaust passage 2 located downstream of the dust collector 3 and the blower 4 and communicates with the closed space 1. A return air passage 5 is formed, an air cooler 6 is interposed in this return air passage 5, and an air purifying device 7 is provided in the exhaust passage 2a downstream of the branch position, and the exhaust/return air volume ratio is controlled. On the other hand, an air supply passage 9 for supplying fresh air to the closed space 1 is provided, and the air supply passage 9 is equipped with an air supply purification device 10 and a control valve for adjusting the amount of air supply. Provided is an exhaust system for decommissioning a nuclear reactor, characterized in that the pressure in the closed space 1 is maintained at a lower pressure than the surrounding environment by adjusting the control valve 8 and the control valve 11. It is something to do.

Each device of the equipment of the present invention and their positional relationship will be explained in detail below.

In FIG. 1, reference numeral 1 denotes a closed space that encloses the decommissioning work area, and contains the bio-shielding concrete 20 of the reactor and this bio-shielding concrete 20.
This closed space 1 is formed by an airtight material 21 that completely covers the upper opening of the housing. The gas-tight material 21 is made of a gas-impermeable material and forms a primary enclosure. Decommissioning work will be carried out within this closed space 1, and this work will be carried out using unmanned machines driven by remote control. Reference numeral 22 indicates an unmanned cutting machine that performs the cutting process. The cutting machine 22 is supported by a main shaft 23 inserted into the closed space 1 so as to be able to slide up and down, and can be controlled by remote control to perform vertical, circular, and oscillating movements.
It is designed to allow telescopic movements and other movements necessary for cutting at various positions. This cutting process is
In addition to mechanical cutting, the equipment of the present invention can also apply thermal cutting, such as by thermal spraying with high-temperature gas. In addition to the cutting machine, other machines necessary for demolition are also operated by remote control.

The exhaust passage 2 is an air passage that exhausts air containing radioactive dust within the closed space 1 to the outside. The exhaust passage 2 basically refers to a path leading from the suction ports provided at various locations in the closed space 1 to the exhaust pipe 24.
There is a branch point 25 in the middle, and from this branch point 25 it is divided into a return air path 5 returning to the closed space 1 and an exhaust path 2a leading to the exhaust pipe 24. From closed space 1 to branching point 2
The exhaust passages 2 up to 5 include air supply passages 13, 28, 29 that take out exhaust air from the suction ports 12, 26, 27, etc. provided at various locations in the closed space 1, and these air passages 13, 28. .

A dust collector 3 and a blower 4 are interposed in the main exhaust passage 2b. The dust collector 3 is a bag filter type dust collector, and the filter clogged with dust is backwashed and cleaned with high-pressure air, and the attached dust is collected by falling downward via a rotary valve. The waste is stored in the waste storage drum 30. The drum 30 is placed on a weighing device, and when the weight reaches a predetermined value, it is converted into an empty container while remaining sealed.

In the illustrated example, a branch point 25 is provided on the discharge side of the blower 4, and the closed space 1 is connected to the branch point 25.
A return air passage 5 is formed which communicates with the air outlet 31 of the air outlet. An orifice 32 and an air cooler 6 are installed in this return air passage 5. The air cooler 6 consists of a cooling coil through which refrigerant or cold water flows, and a part of the air from which dust has been removed by the dust collector 3 is cooled here and then returned to the closed space 1. The orifice 32 serves as a resistance to guide only a portion of the total exhaust gas to the return air path 5, and a depressurizing effect to effectively cool the air in the air cooler 6.

An air purifier 7 and a control valve 8 are installed from the branch point 25 to the exhaust passage 2a of the exhaust pipe 24. This control valve 8 is an automatic control valve. The air purification device 7 has a built-in HEPA filter 33, which collects fine particles that cannot be collected by the dust collector 3 with high efficiency. The automatic control valve 8 is for controlling the displacement/return air amount ratio, and by adjusting the automatic control valve 8, the return air amount can be controlled.

Remote manual adjustment valves 35, 36, 37 are installed in the air supply paths 13, 28, 29, which send out exhaust air from each of the suction ports 12, 26, 27, etc., respectively. , 26, and 27 can be adjusted respectively. At this time, at least one of the suction ports is a movable suction port so that air can be sucked into the vicinity of the cutting machine 22 during operation. That is, in the illustrated example, the suction port 12 consists of a hood that is supported by the main shaft 23 so as to be movable up and down. Make sure to suck in the dust generated during work at its source. The movement of this hood, along with the cutting process, is performed by remote control monitored by a television camera. The hood 12 is connected to the air supply path 13 by a flexible duct 38 via a winder 39 . A cyclone 14 is provided in this air passage 13.
is installed to primarily collect dust. The dust collected here can also be taken out of the machine while being sealed, as in the case of the dust collector 3 mentioned above.

Fresh air is supplied to the closed space 1 from an air supply path 9 in a system separate from the exhaust system configured in this manner.
A supply air purifying device 10 and a control valve 11 for adjusting the supply air amount are attached to the supply air passage 9. This control valve 11 is a remote manual adjustment valve. The air supply purification device 10 has a filter installed therein.

On the other hand, a preliminary exhaust passage 40 is provided for controlling the exhaust amount in an emergency or during non-working hours such as at night or on holidays. This is an air passage leading from the suction port 41 of the closed space 1 to the exhaust pipe 24, and includes a blower 42,
An air purifying device 43, a cyclone 44, an automatic control valve 45, etc. are installed in this air passage. This makes it possible to sufficiently remove dust and control the pressure within the closed space 1 even in an emergency.

According to the equipment of the present invention configured as described above, decommissioning work can be carried out in the closed space 1, which is always controlled to have a lower pressure than the surrounding atmosphere, and the heat and dust generated inside the space can be safely removed from the system. It becomes possible to take it out. In other words, negative pressure control can be easily performed by adjusting the differential pressure regulator DPC1, the automatic control valve 8, and the remote manual control valve 11, thereby preventing the air in the closed space 1 from leaking out of the system. In addition, by introducing fresh outside air and cooling the circulating air, the heat generated within the closed space 1 is effectively taken out of the system and cooled, thereby preventing heat from accumulating inside. Even if the dust is radioactive, it can be removed from the system without being dissipated into the outside air.

[Brief explanation of the drawing]

FIG. 1 is an equipment layout system diagram of the equipment of the present invention. 1... Shield space, 2... Exhaust passage, 3... Dust collection device, 4... Blower, 5... Return air path, 6...
Air cooler, 7...Air purification device, 8...Automatic control valve, 9...Air supply path, 10...Air supply purification device, 1
1... Control valve (remote manual adjustment valve), 12... Mobile suction port (hood), 21... Airtight material, 22...
Cutting machine, 23...main shaft.

Claims (1)

[Claims] 1. A closed space 1 is formed in which the decommissioning work area where the nuclear reactor is dismantled is isolated from the surrounding atmosphere inside the building by airtight material, and a remote-controlled drive system is formed within this closed space 1. Exhaust equipment for unmanned decommissioning work of a nuclear reactor, which incorporates dismantling equipment to
An exhaust passage 2 leading from the inside to the outside is formed, and a dust collector 3 and a blower 4 are connected to the exhaust passage 2.
A return air passage 5 is formed which branches from the exhaust passage 2 located downstream of the dust collector 3 and the blower 4 and communicates with the closed space 1, and an air cooler 6 is connected to the return air passage 5. An air purifying device 7 and a control valve 8 for controlling the exhaust volume/return air volume ratio are installed in the exhaust passage 2a on the downstream side of the branch position, and on the other hand, fresh air is supplied to the closed space 1. An air supply path 9 for supplying air is provided, and an air supply purification device 10 and a control valve 11 for adjusting the air supply amount are provided in the air supply path 9.
An exhaust system for decommissioning a nuclear reactor, which is equipped with a control valve 8 and a control valve 11 to maintain the inside of the closed space 1 at a more negative pressure than the surrounding environment. 2 The exhaust passage 2 is connected to a plurality of suction ports provided in the closed space 1, and at least one of the suction ports is a mobile suction port 12 that sucks air near the decommissioning work area. The exhaust equipment for decommissioning a nuclear reactor according to claim 1, wherein a cyclone 14 is interposed in an air supply passage 13 leading from the suction port 12 to the exhaust passage 2.