KR102430724B1 - Dismantling method of nuclear power plant piping using the pipe freezing seal isolation method - Google Patents

Abstract

The present invention relates to a method for dismantling a nuclear power plant pipe using pipe freezing seal isolation. To completely block the leakage of radioactively contaminated water from a nuclear power plant pipe during operation and dismantling of a nuclear power plant, and to safely and conveniently transport and store a dismantled pipe, the method of the present invention comprises: a first pipe freezing seal isolation step (S1) for installing pipe freezing seal isolation modules at two places at a predetermined interval on the outer circumferential surface of a nuclear power plant pipe to be dismantled, and freezing the inside to form an ice plug area for water blocking; a pipe freezing seal isolation module separation step (S2) for removing the pipe freezing seal isolation modules from the nuclear power plant pipe; a pipe cutting step (S3) for obtaining a dismantled pipe separated from the nuclear power plant pipe by separately cutting a center part of the ice plug area of the nuclear power plant pipe; a cut part shielding step (S4) for sealing an end of each pipe cut in the pipe cutting step with a cover member; and a dismantled pipe transport and storage step (S5) for transporting and storing the dismantled pipe to a radioactive waste storage.

Description

Dismantling method of nuclear power plant piping using the pipe freezing seal isolation method

The present invention relates to a method of dismantling a nuclear power plant pipe using a pipe freezing and shutting method that enables the piping to be dismantled without leakage of contaminated water from a nuclear power plant by using a pipe freezing and shutoff method in which the water is shut off by freezing the pipe.

In general, nuclear power generation is a power generation method that generates electricity by operating a turbine generator with steam generated using energy generated through a nuclear fission chain reaction. Since a large amount of radioactive material is generated and a large amount of heat is generated when such material decays, there is a risk of a major accident in case of negligence in management or a natural disaster.

In the conventional dismantling process of nuclear power plants, the nuclear power plant dismantling method drains radioactive contaminated water in the nuclear power plant pipe and transfers it to a dedicated storage container. In addition to this, there is a problem in that the radioactive contaminated water is discarded as it is when it is not possible to completely drain the radioactively contaminated water due to a special structure such as a pump.

Moreover, in the process of dismantling a nuclear power plant, if radioactive contaminated water from nuclear power plant piping and nuclear power generation facilities is leaked, soil and water pollution will have a profound impact on the ecosystem. The storage technology is desperately needed.

As a result of intensive research on a method to completely block the leakage of cooling water in the nuclear power plant pipe and to recover it when dismantling the pipe of a nuclear power plant, the present inventor paid attention to the fact that the nuclear power plant pipe can be safely dismantled by using the pipe freeze-drying method Thus, the present invention was completed.

Here, the pipe freezing prevention method is the 'pipe rapid freezing module' of Korean Patent Publication No. 10-2014-0129630 (Patent Document 1) proposed by the present inventor or the ' of Korean Patent Registration No. 10-1469079 (Patent Document 2)' Although the 'pipe rapid freezing method' can be applied, the method for dismantling the piping nuclear power plant of the present invention is not limited to the method presented in the patent documents. Since it can be applied, a detailed description of the pipe freezing module in the following detailed description will be omitted.

1. Korean Patent Publication No. 10-2014-0129630 (published on November 7, 2014) 2. Republic of Korea Patent Registration No. 10-1469079 (Notice on November 28, 2014)

The present invention for solving the problems inherent in the above prior art completely blocks leakage of radioactive contaminated water from nuclear power plant operation and nuclear power plant dismantling process, and safely and conveniently transports and stores (storage) the dismantled pipe. An object of the present invention is to provide a method for dismantling nuclear power plant piping using the piping freeze-drying method.

In order to achieve the above object, the nuclear power plant dismantling method of the present invention comprises installing a pipe freezing order module in two places at a predetermined distance on the outer peripheral surface of a nuclear power plant pipe to be dismantled, respectively, and freezing the inside to form an ice plug area for shutting off. First pipe freezing order step; a pipe freezing order module separation step of removing the pipe freezing order module from the nuclear power plant pipe; a pipe cutting step of cutting a central portion of the ice plug area of the nuclear power plant pipe to obtain a dismantled pipe separated from the nuclear power plant pipe; a cut-off shielding step of sealing the end of each pipe cut in the pipe cutting step with a cover member; It is characterized in that it includes.

As a preferred embodiment, after the step of separating the pipe freeze order module, the ice plug area is expanded by reinstalling the pipe freeze order module on the outer peripheral surface of the nuclear power plant pipe at both ends of the ice plug area in the nuclear power plant and freezing the inside, respectively. It may further include a pipe freezing order step.

Here, the cover member includes an inner cover provided to cover the end of the pipe and the outer circumferential surface of the pipe and having an external screw portion formed on the outer circumferential surface, and an outer cover having an inner screw portion fastened to the external screw portion formed on the inner circumferential surface and covering the entire outer surface of the inner cover. And, by forming an airtight space between the outer surface of the inner cover and the inner surface of the outer cover, the cover member may have a heat insulating function by the air layer of the airtight space.

In addition, radiation shielding may be possible by interposing a first weight concrete layer having a specific gravity of 2.5 to 4.0 between the inner surface of the inner cover and the end of the pipe.

In addition, a second weight concrete layer having a specific gravity of 2.5 to 4.0 may be introduced into the airtight space to allow the cover member to shield the radiation, wherein the second weight concrete layer comprises 80 to 90% by weight of the mortar composition and 10 expanded vermiculite particles It can be molded into a blend of ~ 20% by weight and have both radiation shielding and heat insulating properties.

In addition, at least one or a plurality of flat surfaces may be provided on the outer peripheral surface of the outer cover.

According to the nuclear power plant dismantling method of the present invention, it is possible to fundamentally block leakage of radioactive contaminated water that may occur during the dismantling process of a nuclear power plant, and thus it is possible to effectively prevent soil and water pollution caused by the leakage of contaminated water.

In addition, considering that it is difficult to completely drain the radioactively contaminated water due to the special structure of the pump connected to the nuclear power plant, the present invention can completely prevent the leakage of radioactively contaminated water by excluding the draining process of the radioactively contaminated water. have.

In addition, as it is possible to dismantle, seal, transport and store the existing nuclear power plant piping as it is, that is, without draining contaminated water, the use of additional mechanical materials such as drain pipes or fluid storage containers can be excluded, and the dismantling time can be dramatically shortened. It is very economical to be able to

In addition, since the cover member sealed at the end of the dismantled pipe has thermal insulation and radiation shielding properties, it can effectively shield radiation even when stored for a long time, so safety can be doubled.

Therefore, the present invention has the advantage of not only advancing the domestic nuclear power plant dismantling technology in the initial stage of nuclear power plant dismantling, but also increasing the reliability of the nuclear power plant dismantling project.

1 is a block diagram showing the process of a nuclear power plant pipe dismantling method according to the present invention.
2 is a view showing the primary pipe freezing order process of the nuclear power plant pipe dismantling method according to the present invention.
3 is a view showing the secondary pipe freezing order process of the nuclear power plant pipe dismantling method according to the present invention.
Figure 4 shows a pipe cutting process of the nuclear power plant pipe dismantling method according to the present invention.
Figure 5 shows the cut-off sealing process of the nuclear power plant pipe dismantling method according to the present invention.
6 is an enlarged cross-sectional view of part 'A' of FIG. 5 .
7 is a cross-sectional view taken along line 'B-B' of FIG. 6 .
8 is an enlarged cross-sectional view of part 'A' of FIG. 5 according to another embodiment of the present invention.

Since the present invention can have various modifications and can have various embodiments, preferred embodiments of the present invention are exemplified below, and the present invention will be described in detail based thereon. However, this is not intended to limit the present invention to only the illustrated embodiments, and the spirit and technical scope of the present invention includes conventional modifications or equivalents of the illustrated forms to substitutes for industrial wastewater and the like.

In addition, throughout the specification, that a part is 'connected' to another part includes a case in which it is 'directly connected' or 'indirectly connected' with an element, and 'including' a certain element is specifically opposed. Unless otherwise stated, it means that other components may be added, rather than excluding other components.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Terms defined in a commonly used dictionary should be interpreted as being consistent with the meaning of the context of the related art, and cannot be interpreted as having an ideal or excessively formal meaning unless explicitly defined in the present invention.

1 is a block diagram showing a process of a nuclear power plant pipe dismantling method according to the present invention, FIG. 2 is a primary pipe freezing order process among the nuclear power plant pipe dismantling method according to the present invention, and FIG. 3 is a nuclear power plant pipe dismantling method according to the present invention The secondary pipe freezing order process, FIG. 4 shows the pipe cutting process in the nuclear power plant pipe dismantling method according to the present invention, FIG. 5 shows the cutting partial sealing process in the nuclear power plant pipe dismantling method according to the present invention, and FIG. 5 is an enlarged cross-sectional view of portion 'A', and FIG. 7 is a cross-sectional view taken along line 'B-B' of FIG. 6 .

As shown in Figure 1, the nuclear power plant pipe dismantling method using the pipe freezing order method according to the present invention includes a primary pipe freezing order step (S1), a pipe freezing order module separation step (S2), a pipe cutting step (S3), A step of additionally creating secondary ice plug regions on both sides of the primary ice plug region after the pipe freezing order module separation step (S2), including the step of shielding the cut portion (S4) and the dismantling pipe transport and storage step (S5). may further include.

1 and 2, in the first pipe freezing order step (S1), a pipe freeze order module 20 is installed in two places at a predetermined interval on the outer circumferential surface of the dismantling target nuclear power plant pipe 10, respectively. This is a process of forming the ice plug region 12 for water blocking by freezing the fluid 11 inside the pipe 10 .

The pipe freezing order module 20 installs a jacket or a cooling coil surrounding the outer circumferential surface of the pipe as suggested in Patent Document 1 or Patent Document 2, and circulates a refrigerant such as liquid nitrogen into the jacket or cooling coil in the nuclear power plant pipe (10). ) by rapidly freezing the internal fluid 11 to form the water-blocking ice plug 12, the pipe freezing order module 20 can rapidly freeze the water inside the device or other pipes presented in Patent Documents 1 or 2 It can be applied as long as it has been prepared for it.

In the pipe freezing order module separation step (S2), ice plug 12 regions are formed in two places of the nuclear power plant pipe 10 to complete the fluid 11, and then the pipe freeze order module 20 from the nuclear power plant pipe 10 ) is the process of removing (removing).

In the present invention, when considering cutting the portion of the nuclear power plant pipe 10 in which the ice plug 12 area is formed in order to dismantle the nuclear power plant pipe 10, if the ice plug 12 area is narrow, there is a possibility that contaminated water may leak during the pipe cutting process. For this reason, it is necessary to expand the area of the ice plug 12 in a wide range as much as possible.

To this end, according to another embodiment of the present invention, as shown in FIG. 3 , after the pipe freezing order module separation step ( S2 ), the outer peripheral surface of the nuclear power plant pipe 10 at both ends of the ice plug 12 area of the nuclear power plant pipe 10 . The method may further include a secondary pipe freezing order step of expanding the ice plug 12 area by reinstalling the pipe freezing order module 20 in each to freeze the fluid 11 therein.

Here, by making the pipe freezing order module 10 large, the area of the ice plug 12 can be expanded with only one pipe freezing order process. Therefore, it is preferable to separate the primary pipe freezing order process and the secondary pipe freezing order process.

4, in the pipe cutting step (S3), the dismantling pipe 10' separated from the nuclear power plant pipe 10 by cutting the center of the ice plug 12 area of the nuclear power plant pipe 10, respectively. It is a process to obtain

When the nuclear power plant pipe 10 is cut, the fluid 11 of the nuclear power plant pipe 10 as well as the fluid 11 of the dismantling pipe 10' does not flow out by the ice plug 12 to the outside of the nuclear power plant pipe 10 It is possible to completely prevent leakage of the fluid 11 during disassembly.

After obtaining the dismantling pipe 10' from the nuclear power plant pipe 10, the ice plug 12 area is re-installed on the other side (not shown) of the nuclear power plant pipe 10 by installing the pipe freezing order module 20 again. After forming, if the process of cutting the area of the ice plug 12 is repeated, the entire nuclear power plant pipe 10 in the nuclear power plant can be divided and dismantled.

In this case, since it is possible to simultaneously discard the nuclear power plant piping 10 and the fluid 11 therein, there is no need to separately drain the fluid 11 in the nuclear power plant piping 10 and collect it into the fluid 11 storage tank. It is possible to significantly shorten the dismantling time of the pipe 10 and also to reduce the storage space required for waste storage by that much.

The cut-off shielding step (S4) is a process of sealing the ends of each cut pipe (nuclear power plant pipe and dismantling pipe) with the cover member 30 after the process of the pipe cutting step (S3), and the ice plug 12 is Since it melts and becomes the fluid 11 after this elapses, it is preferable to seal each end of the cover member 30 immediately after the pipe is cut.

At this time, in order to delay the melting time of the ice plug 12 to prevent leakage of contaminated water, a step of cutting the pipe ( S3 ) and a step of sealing the cut with the cover member 30 ( S4 ) are performed. During the process, the pipe freezing module 20 installed on both sides of the ice plug 12 may be continuously operated without removing the pipe freezing module 20 until the cover member 30 is completely sealed.

Meanwhile, according to the present invention, in order to delay the melting time of the ice plug 12 after the sealing of the cover member 30 is completed, heat insulating properties may be provided to the cover member 30 .

In order for the cover member 30 to have heat insulation, as shown in FIGS. 6 and 7 , the cover member 30 simultaneously covers the end of each pipe 10 and 10 ′ and the outer peripheral surface of each pipe 10 and 10 ′. An inner cover 310 provided to do so and having an external threaded part 311 formed on its outer peripheral surface, and an internal threaded part 321 fastened to the externally threaded part 311 are formed on the inner peripheral surface, and the entire outer surface of the inner cover 310 is formed. It may be configured to include an outer cover 320 to cover, and at this time, if the airtight space 322 is formed between the outer surface of the inner cover 310 and the inner surface of the outer cover 320, the airtight space ( The air layer is formed by the 322 , so that the cover member 30 may have thermal insulation properties.

As illustrated in FIG. 6 , the external screw part 311 is manufactured to protrude more than the outer circumferential surface of the inner cover 310 or the inner screw part 321 is more protruded from the inner circumferential surface of the outer cover 320 , and then the external screw part When the 311 and the internal screw part 321 are fastened, an airtight space 322 is formed between the inner surface of the outer cover 320 .

The inner cover 310 may be made of a metal material and fixed to each pipe 10,10' by a welding part 312, but means for fixing the inner cover 310 to each pipe 10,10'. In addition to the illustrated welding 312 method, the inner cover 310 is covered after applying an adhesive to the ends of the pipes 10 and 10 ′ or the inner cover 310 , or other fixing means may be applied.

The method of installing the cover member 30 at the ends of each pipe (10, 10') is to first fix the inner cover 310 to the end of each pipe (10, 10') and then attach the outer cover 320 to the inner cover 310 ), or in which the inner cover 310 and the outer cover 320 are already assembled with the cover member 30 assembly at the ends of each pipe (10, 10').

As another embodiment, in order to increase the airtightness of the contact portion between the end of each pipe 10 and 10 ′ and the inner cover 310 , and at the same time to shield the radiation emitted from the fluid 11 or the ice plug 12 , the inner cover A first weight concrete layer 31 may be interposed between the inner surface of the 310 and the ends of each pipe 10 and 10 ′.

Unlike general concrete, heavy concrete is concrete with a specific gravity greater than 2.3, and the specific gravity is increased by using iron ore, barite, iron slabs, etc. as aggregates. When the specific gravity of this heavy concrete is 2.5 to 4.0, more preferably, when the specific gravity is 3.5 to 4.0, since it has a radiation shielding function, it is in the form of a disk between the inner surface of the inner cover 310 and the ends of each pipe 10 and 10'. When the first heavy concrete layer 31 made of

8 is an enlarged cross-sectional view of part 'A' of FIG. 5 according to another embodiment of the present invention.

Referring to FIG. 8 , in order to further increase the radiation shielding properties of the cover member 30 , a second weight concrete layer 32 having a specific gravity of 2.5 to 4.0 may be formed inside the airtight space 322 . At this time, the second weight concrete layer 32 formed in the airtight space 322 is a structure manufactured in advance in the shape of the airtight space 322 before assembling the inner cover 310 and the outer cover 320 of the cover member 30 . It can be provided in a way that is installed first.

As in the above-described embodiment, the first heavy concrete layer 31 is installed between the inner surface of the inner cover 310 and the ends of the respective pipes 10 and 10 ′, and at the same time, the second heavy concrete layer is installed inside the airtight space 322 . When the 32 is formed, it is possible to further increase the radiation shielding property, so that even if the dismantling pipe 10 ′ is stored for a long time in the radioactive contaminant storage, radioactive contamination can be effectively prevented.

Here, 80 to 90 wt% of a mortar composition for molding the second weight concrete layer, and expanded vermiculite, in order to ensure that the second weight concrete layer inserted into the airtight space 322 has both radiation shielding and heat insulation properties. The second weight concrete layer 32 may be manufactured by molding a mixture containing 10 to 20% by weight of the particles.

Here, as the mortar composition for molding the second heavy concrete layer 32, a known heavy concrete mixture may be applied, and thus a detailed description thereof will be omitted.

The expanded vermiculite is expanded by calcining crushed vermiculite with a particle diameter of about 3 mm at high heat to expand it, and is used as a lightweight aggregate for heat insulation because it has porosity. can have at the same time.

When the expanded vermiculite particles are less than 10% by weight compared to the mortar composition for the second weight concrete layer 32, the increase in thermal insulation properties is insignificant. desirable.

On the other hand, at least one or a plurality of on the outer peripheral surface of the outer cover 320 in order to be able to load in multiple layers when transporting the dismantling pipe 10 ′ sealed at both ends through the cover member 30 or storing it in a radioactive material storage. A flat surface 323 may be formed.

The flat surface 323 may be installed in two places at intervals of 180° with respect to the outer circumferential surface as illustrated, although not shown, may be installed in four places at intervals of 90°.

As such, the above description has been described according to a limited embodiment showing the technical idea of the present invention, but the present invention is not limited to a specific embodiment or shape and numerical value, and by changing, mixing, etc., some of the components of the embodiments. Various modifications and variations are possible by those of ordinary skill in the art to which the invention pertains without departing from the gist of the invention, and such modifications and variations should not be individually understood from the technical spirit or prospect of the present invention. will be.

10... nuclear power plant plumbing
10'... dismantling piping
11... fluid
12... ice plug
20... Pipe Freeze Module
30... without cover
31... 1st weight concrete layer
32... 2nd weight concrete layer
310... inner cover
311... External thread part
312... weld
320... outer cover
321... internal thread part
322... confidential space
323... flat surface

Claims (7)

a first pipe freezing order step of forming an ice plug area for shutting off by installing a pipe freeze order module in two places at a predetermined interval on the outer peripheral surface of the nuclear power plant to be dismantled, and freezing the inside;
a pipe freezing order module separation step of removing the pipe freezing order module from the nuclear power plant pipe;
a pipe cutting step of cutting a central portion of the ice plug area of the nuclear power plant pipe to obtain a dismantled pipe separated from the nuclear power plant pipe;
a cut-off shielding step of sealing the end of each pipe cut in the pipe cutting step with a cover member; including,
The cover member includes an inner cover provided to cover the end of the pipe and the outer circumferential surface of the pipe and having an external threaded portion formed on the outer peripheral surface, and an outer cover having an inner threaded portion fastened to the external threaded portion formed on the inner peripheral surface and covering the entire outer surface of the inner cover. includes,
An airtight space is formed between the outer surface of the inner cover and the inner surface of the outer cover, whereby the cover member is provided to be insulated by an air layer,
A method for dismantling a nuclear power plant pipe using a pipe freezing order method, characterized in that a first weight concrete layer having a specific gravity of 2.5 to 4.0 is interposed between the inner surface of the inner cover and the end of the pipe. The method according to claim 1,
After the pipe freezing order module separation step, a secondary pipe freezing order step of expanding the ice plug area by reinstalling the pipe freeze order module on the outer peripheral surface of the nuclear power plant pipe at both ends of the ice plug area in the nuclear power plant pipe and freezing the inside, respectively. A nuclear power plant pipe dismantling method using a pipe freezing order method, characterized in that it further comprises. delete delete The method according to claim 1,
A method of dismantling a nuclear power plant pipe using a pipe freeze-order method, characterized in that a second weight concrete layer having a specific gravity of 2.5 to 4.0 is formed in the airtight space. 6. The method of claim 5,
The second weight concrete layer is a nuclear power plant dismantling method using a piping freeze-order method, characterized in that it is molded with a mixture of 80 to 90% by weight of a mortar composition and 10 to 20% by weight of expanded vermiculite particles. The method according to claim 1,
A method for dismantling nuclear power plant piping using a piping freeze-order method, characterized in that at least one or a plurality of flat surfaces are provided on the outer peripheral surface of the outer cover.

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