JPS61124896A - Piping for nuclear power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to the outflow of internal fluid due to rupture of piping used in nuclear power plants in which high-temperature, high-pressure fluid flows, and the fluid This invention relates to piping for a nuclear power plant that prevents the whiplash phenomenon caused by the ejection reaction force.

[Technical background of the invention and its rR issues]

In order to ensure the safety of nuclear power plant piping, it is designed with hypothetical pipe rupture in mind. For this pipe rupture point, a relatively high stress area is taken into consideration.

If a pipe rupture were to occur, it is thought that the following steps would occur.

(I) Cracks occur in the piping.

<It) Cracks grow. However, in this state, the pipe has not yet broken.

(it) A crack penetrates the pipe wall and internal fluid begins to leak through the hole.

(IV) The crack grows further and becomes quite large,
Furthermore, if an excessive load is applied, the pipe will break.

In an actual nuclear power plant, from (I) above to (rV
) Measures have been taken for each of the above steps, and although there is no possibility of pipe breakage, pipe breakage is assumed in consideration of further safety.

Assuming a pipe rupture, when the internal fluid is ejected from the pipe rupture, the pipe will be whipped by the ejection reaction force. For this reason, in the past, restraints were installed at the parts where pipes were expected to break in order to prevent such whiplash. FIG. 3 is a partial side view showing an example of restraint installation in a conventional nuclear power plant. In other words, the restraint 3 is installed to prevent whiplash caused by a rupture at the expected rupture site 2 of the pipe 1. This restraint 3 prevents whiplash of the pipe 1 due to the reaction force of fluid ejection by restraining the movement of the pipe 1 due to the breakage when the pipe 1 breaks, and prevents whiplash of the pipe 1 from occurring due to whiplash of the pipe 1. This prevents damage to adjacent piping 5 and equipment not shown. The restraint 3 is only fixed to the struf- ture 4, and this struf- ture 4 is connected to the restraint 3.
It is often installed specifically for the sole purpose of fixing. In such conventional examples, restraints 3 are installed assuming a pipe breakage, but technically it is not necessarily necessary to assume a pipe breakage, and it is considered sufficient to consider a small breakage opening. . Although the internal fluid is ejected from the rupture port, the reaction force of this fluid ejection is much smaller than that in the case where the piping is assumed to be ruptured. Another conventional example constructed based on this viewpoint will be described below.

Nuclear power plant piping is coated with a heat insulating material and a dew-proofing material around the piping in order to retain heat and prevent dew. Figures 4 and 5 show one line of piping that has a part to be inspected during service (corresponding to a predicted breakage part). Insulation materials can be removed and attached to the parts that will be inspected during service. In addition, as shown in FIG.
It is installed near No. 2. In FIG. 4, the outer periphery of the pipe 6 is coated with a heat insulating material 7.8, and the outer circumferential surface of the heat insulating material 7.8 is further surrounded by an aluminum plate 9.10, which can be attached and detached at the expected breakage site 12. A heat insulating material 7 is fixed to with a buckle 11. In FIG. 5, a heat insulating material 14.15 is provided on the outer surface of a curved pipe 13, an aluminum plate 16.17 is further provided on the outer surface of the heat insulating material 14.15, and a restraint 20 is attached to a strafe 21 at a predicted breakage site 22. A fixed example is shown. Note that a heat insulating material 19 is provided roughly at the location where the restraint 20 is provided, and the outer surface of the heat insulating material 15 at the expected breakage location 22 is detachable, and the aluminum plate 17 is fixed with a buckle 18. By the way, piping for nuclear power plants is regularly inspected once a year: an ultrasonic flaw detection test is usually carried out.

This periodic inspection is important to ensure the integrity of the nuclear power plant. Currently, restraints 3.20 and strutures 4, 21 for fixing the restraints 3.20 are provided at various locations on the piping 1.6.13, and therefore periodic inspections require a lot of time. If the number of restraints 3.20 and strutures 4, 21 were reduced or eliminated, the working space would be larger;
Improves the workability of ultrasonic flaw detection tests and shortens periodic inspection work time.

One way to reduce the number of restraints 3 and 20 installed is to install piping and equipment.

This means that even if the pipe 1.6 breaks and is whiplashed, Im can be moved to the pipe 1.6.1 without colliding with the pipe 5 adjacent to the broken pipe 1, 6.13 or equipment (not shown).
This is a method to prevent the number from increasing to 3 or more. However, according to this method, there is a problem in that the piping and equipment must be installed farther apart than necessary, resulting in a more complicated arrangement.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the above-mentioned background art, and its purpose is to control the outflow of internal fluid from a pipe break and prevent the whiplash phenomenon caused by the ejection reaction force of this fluid in a nuclear power generation plant. The aim is to provide plumbing for

[Summary of the invention]

The present invention is designed to prevent piping from rupture in nuclear power plant piping, where high-temperature, high-pressure fluid flows, in order to control the outflow of internal fluid due to piping rupture, and to prevent the whiplash phenomenon caused by the ejection reaction force of the fluid. The pipe is characterized in that a rigid outward body made of gold III or ceramic, for example, is provided on the outside of the piping, which is removable during inspection during service. According to the present invention, when a pipe ruptures, there is an effect of preventing damage to other pipes and equipment from expanding beyond that pipe.

[Embodiments of the invention]

A first embodiment of the piping according to the present invention will be described below with reference to FIG. In FIG. 1, a heat insulating material 25 is provided outside the piping 23 to be inspected during the service period in the vicinity of a predicted fracture site 29, and a semi-cylindrical shape is further placed outside the heat insulating material 25 and the heat insulating materials 24 adjacent on both sides. This is an example of piping for a nuclear power plant in which a two-divided outer cylinder body 26 is fixed with a stopper 27. However, in this example, the expected fracture location 2
For example, a crack occurs in 9, and this grows into an open crack,
Even if high-temperature, high-pressure internal fluid is ejected from this opening, it collides with the outer cylindrical body 26, reducing the ejection speed of the fluid and reducing the so-called ejection reaction force. The external body 26 is made of a rigid metal or ceramic and has a shape that can withstand the outflow of fluid at high temperature and high pressure (up to 70 atmospheres and 288° C. in a boiling water reactor). Furthermore, the whiplash phenomenon caused by the reaction force of fluid ejection can also be prevented by suppressing the outflow of fluid.

In this manner, by providing the outer cylinder 26 at the expected breakage site 29, the restraint 20 and struture 21 shown in FIG. 5 as a conventional example can be omitted.

FIG. 2 shows a second embodiment of the present invention, in which an outer cylindrical body 33 that can be divided into two is installed on the outside of the piping 30 to be inspected during the service period in the vicinity of a predicted fracture site 38, and the outer cylindrical body 33 is body 3
This is an example of piping for a nuclear power plant in which a heat insulating material 32 is installed on the outside of the piping. That is, in FIG. 2, the pipe 30
The outer surface of the insulation material 3 is covered with an aluminum plate 35.
1 is provided. Possible breakage site 38 of the piping 30
is provided with an outer cylindrical body 33 and fixed with a buckle 34,
Further, a thin heat insulating material 32 is provided on the outer surface of the outer cylinder body 33. Further, an aluminum plate 36 is fixed to the outer surface of the heat insulating material 32 by a stopper 37. in this case,
Since the clearance between the outer cylindrical body 33 and the pipe 30 is reduced, the pipe thickness can be made thinner and the weight can be reduced compared to the first embodiment shown in FIG. 1 for pipes having the same outer diameter. In addition, by reducing the clearance, it is possible to further suppress the outflow of high temperature and high pressure fluid due to crack openings in the piping, which is also effective in preventing the whipping phenomenon of the piping. In this way, by reducing the clearance between the outer cylinder 33 and the pipe 30, the thickness of the outer cylinder 33 can be reduced. Furthermore, a heat insulating material 32 is placed on the outside of the outer cylinder body 33.
By providing this, it is possible to provide piping having a shape with fewer protrusions. [Effects of the Invention] As explained above, the present invention provides an outer cylinder that can be divided into two at the expected rupture part of piping for a nuclear power plant, thereby controlling the outflow of internal fluid due to crack openings and preventing piping from rupturing. It is possible to prevent the whiplash phenomenon caused by the reaction force of the internal fluid flowing out in some places. In other words, in conventional piping, a restraint was provided to prevent the whiplash phenomenon of the piping, but in the present invention, by providing an outer cylinder around the piping to be inspected during the in-service period, it is possible to prevent the internal fluid from flowing out. It is possible to control this, prevent the whiplash phenomenon caused by the reaction force of the ejected fluid, and eliminate the need to install restraints, strutures, etc. This expands the work space, improves the workability of periodic inspections, and shortens the work time.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing respective embodiments of piping for a nuclear power plant according to the present invention, FIG. 3 is a side view showing an example of conventional piping restrained, and FIG. 1 and 5 are 1iIIIi side views showing conventional piping. 1.5.6, 13.20.30... Piping, 2°12.
22, 29. 38...Possible pipe breakage location, 3°20.
...Restraint, 4,21...Strafture,
7.8.14, 15, 19, 24. ,．． 25.31",
32...Heat insulation material, 26.33...Outer cylinder body, 9,10
．． 16,17.28.35.36... Aluminum plate, 27.37-... Clasp, 11.18.34... Buckle. Representative Patent Attorney Kensuke Chika (and 1 other person) Tsune I
Shout $ 2 Diagram j: j Tea 3 Sunflower 4 Hard

Claims (1)

[Scope of Claims] 1. Piping for a nuclear power plant through which high-temperature, high-pressure fluid flows, characterized in that a rigid outer cylinder is removably provided at a portion of the piping where fracture is expected. Piping. 2. The piping for a nuclear power plant according to claim 1, wherein the rigid outer cylinder is made of metal or tough ceramic.