JPH026400Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention relates to the piping system of a nuclear power plant, and in particular, in order to maintain the cleanliness inside the system piping of a power plant, separate pipes such as rust preventive injection piping are used. The present invention relates to a piping connection structure in which system piping can be connected detachably.

[Technical background of the invention and its problems]

In general, in nuclear power plants, there is a strong demand for the reactor to operate efficiently and at a high availability rate. Performing inspections quickly and accurately is an essential condition for maintaining the integrity of nuclear reactors.

On the other hand, in this type of nuclear power plant, a large number of system pipes are installed within the reactor building, and heat transfer and cooling within the reactor are performed through fluid flowing within each system pipe.

By the way, when system piping installed in a nuclear power plant is used for a long period of time, rust occurs due to the oxidation effect of the air contained in the fluid inside the pipe, and iron content (hereinafter referred to as "crud") in the rust that occurs occurs. is mixed into the fluid inside the pipe and comes to flow together with the fluid inside the pipe. When the crud contained in the pipe fluid passes through the reactor core, it receives heat from the core and becomes radioactive. If this activated crud adheres to the inner wall surface of the system piping, the entire system piping becomes radioactive and has a serious negative impact on the health management of employees. A device is provided for separating and removing the crud from the fluid within the device and pipes. However, both devices are concerned with processing when crud occurs, and are not necessarily designed to prevent crud from occurring.

It is important to reduce the occurrence of crud from the time of construction of a nuclear power plant, and for this purpose it is necessary to take measures to suppress the occurrence of crud at the stage of manufacturing various equipment and connecting piping. In the actual construction work of a nuclear power plant, most of the work involves connecting the system piping, and since this piping connection work greatly contributes to the occurrence of crud, the inner surfaces of the piping are cleaned when the system piping connections are completed. work is done.

This cleaning work is reasonably effective in removing foreign matter such as crud in the system piping, but the occurrence of crud is mainly caused by moisture in the fluid in the pipes and oxidation by residual water, and the amount of crud is small. It depends on the maintenance and management of the cleanliness inside the system piping after the cleaning work is completed. For this reason, in the system piping after cleaning,
In some cases, inert gas such as _N2 or additives with high rust prevention effects are injected to prevent rust from forming.

However, in order to inject a catalyst such as an inert gas or a rust preventive agent, remove the valve flanges 4a and 5a of the valves 4 and 5 attached to the system piping 1 and vent/drain piping 2 and 3, as shown in Figure 1. This is also achieved by providing the system piping 1 with an injection tube seat 6, injection piping 7, and valves 8a and 8b.
In the former case, it is necessary to disassemble the pipes after laying the system piping 1, which is completely unsuitable after restarting the furnace operation, and in the latter case, the number of points subject to fluid leakage increases, and although it is a suitable injection method, do not have.

In addition, the system piping 1 includes vent/drain piping 2,
3 is always branched and connected to the drainage system funnel 9, but the conventional vent/drain pipes 2 and 3 are only connected to the drainage system funnel 9 as shown in FIG. The pipe 2 and the drain pipe 3 could not be used as pipes for injecting a catalyst such as a rust preventive agent.

[Purpose of invention]

This idea actively utilizes piping branched from the nuclear power plant's system piping to create a nuclear power plant with a simple structure that allows for the injection of rust preventives and other catalysts without disassembling the system piping. The purpose is to provide a piping system.

[Summary of the idea]

In order to achieve the above-mentioned object, this invention is a piping system of a nuclear power plant in which piping branched from the system piping is connected to a funnel, and an internal thread that opens into the funnel is formed at the funnel connection part of the piping, The structure is such that piping from another system can be detachably connected to this internal thread.

[Example of idea]

An embodiment of this invention will be described with reference to the accompanying drawings.

FIG. 3 shows a part of the piping system of this invention installed in a nuclear power plant, and the reference numeral 10 in the figure is the system piping of the single piping system of the nuclear power plant. A valve 1 is located in the middle of this system piping 10.
A vent pipe 12 and a drain pipe 13 are branched from both sides of the valve 11 so as to be openable and closable. The vent pipe 12 is connected to a drainage system funnel 16 via valves 14 and 15 provided in the middle. On the other hand, the drain pipe 13 is also connected to a drainage system funnel 19 via valves 17 and 18, and both pipes 12 and 13 are connected to the drainage system funnels 16 and 19 through a joint 2, as shown in FIG.
Tightly attached via 0.

As shown in FIG. 4, the drainage system funnels 16 and 19 are installed on the floor 21 of the reactor building, a perforated plate 22 that acts as a filter is removably housed inside, and a drainage pipe 23 is connected to the bottom. . The top openings of the drainage system funnels 16 and 19 are removably covered with a lid 24.

Further, the connecting joint 20 is formed with an internal thread 25 as shown in FIG. This internal thread 25 opens into the drainage system funnels 16 and 19,
Desirably, the drain system funnels 16 and 19 are formed in a tapered shape so as to widen toward the inside. A separate line of piping 27 from inside the drainage funnels 16 and 19 is removably connected to this internal thread 25 via a connecting joint 28, as shown in FIG. Connection joint 28
a may have a structure as shown in FIG. 8, or may have another joint structure.

Next, the operation of this invention will be explained.

If you wish to inject a rust preventive agent or an inert gas such as nitrogen gas into the system piping 10, remove the lids 24 and perforated plates 22 of the drainage system funnels 16 and 19, and insert them into the vent piping 12 or drain piping 13. Connecting joint 28 from the inside of drainage system funnels 16 and 19
Or attach (thread) 28a and connect this connection joint 2.
8 or 28a is connected to another system of piping 27 such as a rust preventive injection piping.

After this connection is completed, pipe 2, such as rust preventive injection pipe, etc.
A catalyst such as a rust preventive agent sent through the pipe 7 is injected into the system pipe 10 through the vent pipe 12 or the drain pipe 13 to apply rust prevention to each system pipe 10.
At that time, the rust preventive agent, etc. is injected into the drainage system funnel, which is not affected by the pressure of the fluid flowing inside the system piping 10, by actively utilizing the internal threads 25 of the drain piping 12 and vent piping 13. Therefore, it is completely unnecessary to disassemble the valve flange portion of the system piping 10 which is directly subjected to the pressure action of the fluid in the pipe as in the conventional method, and leakage of the fluid in the pipe can be effectively prevented.

[Effect of idea]

As described above, in the nuclear power plant piping system according to this invention, an internal thread that opens into the funnel is formed at the funnel connection part of the pipe that is branched from the system piping and connected to the funnel. It has a structure that allows pipes from other systems to be detachably connected to the threads, so it has a simple structure that only has internal threads formed at the funnel connection part of the pipes, allowing the fluid flowing inside the system pipes to leak to the outside. Catalysts such as rust preventive agents can be reliably injected without any problems. Moreover, in order to inject anti-rust agents, etc., there is no need for the troublesome disassembly and assembly work of partially disassembling the valve flange part of the system piping, and there is no need to prepare a pipe seat or injection piping system in the system piping in advance. It has the effect that there is no waste.

[Brief explanation of the drawing]

Figure 1 shows the piping system of a conventional nuclear power plant, and Figure 2 shows the vent of the piping system. Diagram showing the connection structure of drain piping to funnel, 3rd
The figure shows an example of a piping system for a nuclear power plant according to this invention, and FIG. 4 shows a vent used in the piping system of this invention. 5 is a cross-sectional view showing the connection structure of the drain pipe to the drainage system funnel, FIG. 5 is a plan view taken along the line V-V in FIG. 4, and FIG. Figure 7 is an enlarged view showing the connection structure of the drain piping funnel. FIG. 8 is a diagram showing a state in which a pipe of another system is connected to the drain pipe, and FIG. 8 is a diagram showing a modification of the pipe connection state shown in FIG. 7. 10... System piping, 11... Valve, 12... Vent piping, 13... Drain piping, 16, 19... Drain system funnel, 20... Connection joint, 25... Internal thread, 27... Other system's Piping (corrosion inhibitor injection piping),
28, 28a... Connection joint.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a piping system for a nuclear power plant in which piping branched from the system piping is connected to a funnel, an internal thread that opens into the funnel is formed at the funnel connection part of the piping, and this internal thread A piping system for a nuclear power plant characterized by having a structure in which piping from another system can be detachably connected to the piping system for a nuclear power plant. 2. The piping system for a nuclear power plant according to claim 1 of the utility model registration claim, wherein the funnel is a drainage system funnel provided on the floor of the reactor building, and the piping of the separate system is piping for injecting a catalyst such as a rust preventive agent. 3. The piping branched from the system piping is a drain piping or vent piping, and this piping is connected to the funnel through a connecting joint, and the scope of the utility model registration claim is that the connecting joint is formed with an internal thread that opens into the funnel. Piping system of the nuclear power plant described in paragraph 1. 4. The piping system for a nuclear power plant according to claim 3, wherein the internal thread formed on the connection joint is formed in a tapered shape so as to expand toward the inside of the funnel.