JP2022157806A - Method for improving plant environment - Google Patents

Abstract

To provide a method for improving a plant environment capable of safely advancing the work.SOLUTION: Disclosed is a method for improving a plant environment which improves a plant environment contaminated by radiation. The method for improving a plant environment which includes the steps of: performing decontamination from a high place to a low place inside a building; confirming the improvement degree of the environment after the completion of decontamination; and removing the plant equipment from the low place to the high place inside the building after confirming the improvement degree of the environment.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a method for improving a plant environment.

When an adverse event occurs at a nuclear power plant, it is necessary to consider contamination of each part by radiation when decommissioning the plant. As a technique related to this type of work, for example, the technique described in Patent Document 1 below is known. Patent Literature 1 describes a technique related to the removal work of the structure of the containment vessel. In this technique, the structure of the reactor containment vessel is first shredded, and the shredded pieces are placed in a storage container and stored in a pool. The container is then sealed within the shielded container. This is said to reduce the radiation exposure of workers.

Japanese Patent Application Laid-Open No. 2001-21689

However, in the plant where the adverse event occurred, a large number of contaminated equipment and facilities are arranged in addition to the reactor containment vessel. Techniques and methods for safely removing these devices and facilities have not been studied in the past.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a method for improving a plant environment that allows work to proceed safely.

In order to solve the above problems, a method for improving a plant environment according to the present disclosure is a method for improving a plant environment contaminated by radiation, comprising the steps of decontaminating from a high place to a low place inside a building; After confirming the degree of environmental improvement after the decontamination is completed, and after confirming the degree of environmental improvement, removing plant equipment from low to high places inside the building.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a method for improving a plant environment that allows work to proceed safely.

4 is a flow chart showing steps of a plant environment improvement method according to an embodiment of the present disclosure; It is a schematic diagram which shows an example of a structure inside a building. 1 is a plan view showing the configuration of a decontamination tool according to an embodiment of the present disclosure; FIG. FIG. 4 is a cross-sectional view showing a state in which the decontamination tool according to the embodiment of the present disclosure follows the surface of the pipe; FIG. 4 is a cross-sectional view showing a state in which a decontamination tool according to an embodiment of the present disclosure follows the surface of a cable; 1 is a plan view showing the configuration of a cutting tool according to an embodiment of the present disclosure; FIG. FIG. 10 is a plan view of a modified cutting tool according to an embodiment of the present disclosure; FIG. 4 is an explanatory diagram showing how the pipe is cut by the cutting tool according to the embodiment of the present disclosure;

(Plant environment improvement method and building configuration)
Hereinafter, a method for improving a plant environment according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 8. FIG. This improvement method is particularly suitable for removal work (decommissioning work) of a nuclear power plant in which an adverse event has occurred.

As shown in FIG. 1, this improvement method includes step S1 of decontaminating the interior of the building, step S2 of confirming the degree of environmental improvement, and step S3 of removing plant equipment.

Here, as shown in FIG. 2, in this embodiment, the wall surface 1 inside the building is divided into three sections according to height, and the work is performed. The interior of the building has a height of, for example, about 8 m per floor. Areas between 0 and 2m from the floor are defined as “low places”. The area between 2m and 4m is called the "middle place". Furthermore, the area between 4m and 8m is defined as "high place". Piping as plant equipment and cables (referred to as interfering objects 2) are laid in each area.

In step S1 for performing the above decontamination, decontamination is performed sequentially from a high place to a low place. In this case, it is permissible to decontaminate mid- and low-level areas after finishing all high-level work. You can work from high to low again.

(Configuration of decontamination tool)
When performing decontamination in step S1, a decontamination tool 80 as shown in FIGS. 3 to 5 is preferably used. This decontamination tool 80 has a pad 10 , a vapor supply section 11 , a suction section 12 , a suction tube 13 and a decontamination tool body section 14 . The pad 10 is made of elastically deformable foamed resin such as sponge or urethane. By pressing the pad 10 against the interfering object 2, the rear surface 10a of the pad 10 can follow the unevenness of the front surface 2a of the interfering object 2 (see FIG. 4 or FIG. 5).

A steam supply unit 11 is provided on the side opposite to the back surface 10a of the pad 10 . The steam supply unit 11 supplies high-temperature, high-pressure steam introduced from the outside to the pad 10 . The steam that has passed through the holes inside the pad 10 is sprayed toward the interfering object 2 from the rear surface 10a. The sprayed vapor captures dust containing radioactive substances adhering to the interfering object 2 .

The suction part 12 and the suction tube 13 are provided adjacent to the pad 10 . The suction unit 12 sucks the dust wiped off by the steam spray with negative pressure. Dust sucked by the suction unit 12 is removed and accumulated by a filter and a strainer provided outside. The decontamination tool body 14 integrally supports the pad 10 and the suction unit 12 . When using this decontamination tool 80, as indicated by the arrow in FIG. Move the decontamination tool 80 as follows. As a result, the dust wiped off by the front pad 10 is sequentially sucked by the rear suction section 12 .

Moreover, decontamination work using the decontamination tool 80 described above is desirably performed from a remote location with the decontamination tool 80 attached to the tip of a remotely controllable robot arm.

(Confirmation of environmental improvement)
After step S1, step S2 is executed to check the degree of improvement of the environment. In this step S2, the radiation dose inside the building after decontamination is measured. If it is determined in step S2 that the radiation dose is equal to or less than the predetermined threshold value, the subsequent step S3 is executed. On the other hand, when the radiation dose is equal to or greater than the threshold, further decontamination is performed by executing step S1 again.

(Removal of plant equipment)
In step S3, the interfering objects 2 including pipes and cables are removed from the inside of the building. When removing the interfering object 2, work is performed sequentially from a low place to a high place, contrary to step S1. In this case as well, after completing all the work in low places, it is possible to carry out removal work in middle and high places, or after working from low places to high places only in a certain area, other areas You may work from low place to high place again with .

In step S3, the cutting tools 90, 90b shown in FIGS. 6 and 7 and the supporting device 100 shown in FIG. 8 are preferably used. The cutting tool 90 has a cutting tool main body 20 that houses an electric motor and the like, and a pair of cutting parts 21 and a gripping part 22 projecting from the cutting tool main body 20 . The cutting part 21 is, for example, a wire saw or a band saw, and is rotatable about a rotation axis in the cutting tool main body 20 in a direction intersecting the obstacle 2 (for example, a vertical direction). The gripping portion 22 can grip the interfering object 2 from above and below. The pair of cutting parts 21 are arranged so as to sandwich the holding part 22 from both sides.

By rotating the pair of cutting portions 21 while the interfering object 2 is held by the holding portions 22, a portion of the interfering object 2 is cut and removed.

Note that it is also possible to adopt a configuration in which a pair of gripping portions 23 are arranged so as to sandwich one cutting portion 21, as in a cutting tool 90b shown as a modified example. This cutting tool 90b is suitably used when cutting a relatively large-diameter pipe. Further, when cutting such a large-diameter pipe, a support device 100 as shown in FIG. 8 is used in order to resist the reaction force at the time of cutting.

The support device 100 includes a leg portion 30 fixed on the floor surface, a base 31 arranged at the upper end of the leg portion 30, and projecting upward from the base 31 and diametrically sandwiching the interfering object 2. and a support portion 32 capable of While the interfering object 2 is supported from below by the supporting device 100, the cutting operation is performed at the position indicated by the broken line in FIG. 8 using the cutting tool 90 or the cutting tool 90b. As a result, a portion of the interfering object 2 is removed. By continuously repeating such work, the interfering object 2 is removed.

It should be noted that it is desirable that the removal work using the cutting tools 90 and 90b be performed from a remote location with the cutting tools 90 and 90b attached to the tip of a robot arm that can be remotely controlled (however, the rigidity of the cutting tool and weight considerations, there is also the possibility of not going through a robot arm). On the other hand, it is also possible for workers to directly perform the removal work only in low places.

(Effect)

According to the above method, first, by performing decontamination from a high place to a low place, dust containing radioactive substances can be brushed off in advance toward the low place before proceeding with the work. As a result, the amount of dust scattered around can be minimized. Furthermore, after that, by removing the plant equipment (interfering object 2) from the low place to the high place, it is possible to improve the accessibility of the work equipment and the efficiency of the work.

In step S1 for decontamination, dust containing contaminants is wiped off by spraying steam, and then sucked.

According to the above method, the dust is wiped and sucked while being lifted from the surface of the interfering object 2 by spraying the steam. Therefore, dust containing contaminants can be wiped and sucked without being scattered around.

Furthermore, by using the decontamination tool 80 described above, it is possible to decontaminate a large area at once by spraying steam while making the pad 10 follow the surfaces of the pipes and cables. Moreover, since the pad 10 can easily follow the unevenness of the interfering object 2, it is possible to further reduce the possibility of dust scattering around.

In step S2 of confirming the degree of improvement of the environment, the radiation dose inside the building is measured, and when the radiation dose falls below a predetermined threshold, step S3 of removing the plant equipment is executed.

According to the above method, the plant equipment is removed after the radiation dose has sufficiently decreased and safety has been confirmed. As a result, work safety and efficiency can be further enhanced.

In addition, in the step S3 of removing the plant equipment, the pipes and cables, which are the plant equipment (interfering object 2), are supported from below while the pipes and cables are cut from above.

According to the above method, the pipes and cables are cut from above while being supported from below. As a result, it is possible to prevent the pipes and cables from becoming unstable due to the reaction force at the time of cutting. As a result, work safety and efficiency can be further enhanced.

The embodiments of the present disclosure have been described above. Various changes and modifications can be made to the above methods and configurations without departing from the gist of the present disclosure. For example, in the above embodiment, the area of 0 to 2 m from the floor is defined as "low place", the area of 2 m to 4 m is defined as "middle place", and the area of 4 m to 8 m is defined as "high place". explained. However, these height classifications and standards are only examples, and depending on the location, it may be classified into only two types, low and high, or four or more classifications may be used depending on the height. Each numerical value indicating the height is also an example, and can be changed as appropriate in consideration of work efficiency and safety.

<Appendix>
The method for improving the plant environment described in each embodiment is grasped, for example, as follows.

(1) A method for improving a plant environment according to a first aspect is a method for improving a plant environment contaminated by radiation. A step S2 of confirming the degree of improvement of the environment after the dyeing is completed, and a step S3 of removing the plant equipment from low places to high places inside the building after confirming the degree of improvement of the environment.

According to the above method, by first decontaminating from a high place to a low place, it is possible to proceed with the work after dust is removed in advance toward the low place. Furthermore, after that, by removing the plant equipment from low to high places, it is possible to improve the ease of access to work equipment and the efficiency of work.

(2) In the method for improving the plant environment according to the second aspect, in the decontamination step S1, dust containing contaminants is wiped off by spraying steam and then sucked.

According to the above method, by spraying steam, dust containing contaminants can be wiped and sucked without being scattered around.

(3) In the method for improving the plant environment according to the third aspect, in the decontamination step S1, a pad 10 that is elastically deformable so as to follow the surfaces of the pipes and cables, and through the pad 10 A steam supply unit 11 that sprays the steam onto the surface, and a suction unit 12 that is provided adjacent to the pad 10 and sucks the wiped dust.

According to the above method, it is possible to decontaminate a large area at once by spraying steam while making the pad 10 follow the surfaces of the pipes and cables. In addition, it is possible to further reduce the possibility of dust scattering around.

(4) In the method for improving the plant environment according to the fourth aspect, in the step S2 of confirming the degree of improvement of the environment, the radiation dose inside the building is measured, and the radiation dose becomes equal to or less than a predetermined threshold. If so, step S3 of removing the plant equipment is executed.

According to the above method, the plant equipment is removed after the radiation dose has sufficiently decreased and safety has been confirmed. As a result, work safety and efficiency can be further enhanced.

(5) In the plant environment improvement method according to the fifth aspect, in the step S3 of removing the plant equipment, the pipes and cables, which are the plant equipment, are supported from below and the pipes and cables are removed from above. disconnect.

According to the above method, the pipes and cables are cut from above while being supported from below. As a result, it is possible to prevent the pipes and cables from becoming unstable due to the reaction force at the time of cutting. As a result, work safety and efficiency can be further enhanced.

1 wall surface 2 interfering object 2a surface (surface of interfering object)
10 pad 10a back surface (back surface of pad)
11 Steam supply unit 12 Suction unit 13 Suction pipe 14 Decontamination tool main unit 20 Cutting tool main unit 21 Cutting unit 22, 23 Grip unit 30 Leg 31 Base 32 Support unit 80 Decontamination tool 90, 90b Cutting tool 100 Support device

Claims (5)

A method for improving a plant environment contaminated by radiation, comprising:
a step of decontaminating from a high place to a low place inside the building;
confirming the degree of improvement of the environment after the decontamination is completed;
After confirming the degree of improvement of the environment, removing the plant equipment from low places to high places inside the building;
A method for improving the plant environment, including 2. The method for improving the plant environment according to claim 1, wherein in the decontamination step, dust containing contaminants is wiped off by spraying steam and then sucked. In the decontamination step,
a pad elastically deformable to conform to the surface of the piping and cables;
a steam supply that sprays the steam onto the surface through the pad;
a suction unit provided adjacent to the pad for sucking the wiped dust;
3. The method for improving the plant environment according to claim 2, wherein a removal tool comprising In the step of confirming the degree of improvement of the environment, the radiation dose inside the building is measured,
4. The method for improving the plant environment according to any one of claims 1 to 3, wherein the step of removing the plant equipment is executed when the radiation dose falls below a predetermined threshold. 5. The plant environment according to any one of claims 1 to 4, wherein the step of removing the plant equipment cuts the pipes and cables from above while supporting the pipes and cables as the plant equipment from below. improvement method.

Images