JPH01237491A - Piping for feed liquid - Google Patents

Abstract

PURPOSE:To plan the reduction of thermal stress in the neighborhood of a connecting part by radially arranging a plurality of thermal sleeves with relative intervals on the inner face of a safe end connected to a single tube part on the low temperature side. CONSTITUTION:A plurality of thermal sleeves 5A, 5B are concentrically arranged on the inner face of a safe end 3 connected to a single water feed tube part 4 and a nozzle 2. Further, a side end part at the side of low temperature of a first cylindrical hollow part 6A between the end 3 and a sleeve 5A and the second cylindrical hollow part 6B, which is moved to the side of low temperature, between the sleeves 5A, 5B are inclined to form. The temperature distribution in the end 3 and the sleeves 5A, 5B is made to function so as to gradually increase in the radially inner direction and the inner direction of a vessel. Therefore, the unevenness of the temperature distribution can be lessened and the production of thermal stress can be reduced.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to liquid supply piping, and in particular, it is used to transfer a low temperature liquid into a high temperature container, etc., such as a water supply piping in a boiling water reactor. This relates to a technology that aims to reduce stress near the connection point between the pipe that feeds the pipe and the nozzle.

"Conventional technology" Conventionally, for example, in a water supply piping system in a boiling water reactor,
In addition to sending low-temperature water supply into a high-temperature atmosphere,
In order to reduce the occurrence of thermal stress due to temperature differences, a double tube structure as shown in FIG. 4 is used. That is, a single pipe section 4 for water supply is connected to the outside of the nozzle 2 and the safe end 3 of the reactor pressure vessel 1, and a thermal sleeve 5 is disposed on the inner surface of the safe end 3, so that the nozzle 2 and the safe end 3 are connected to each other. By forming a cylindrical hollow part 6 between the reactor pressure vessel 3 and the thermal sleeve 5, the feed water is guided into the inside of the reactor pressure vessel 1 while being prevented from directly contacting the high temperature part. For this reason, nozzle 2, which is a pressure-resistant pipe,
and Seifend 3 have a structure that does not apply stress due to sudden temperature changes.

"Problem to be Solved by the Invention" However, with the liquid supply piping having the structure described above, the temperature change in the cylindrical hollow part 6 outside the thermal sleeve 5 is
Although it is gradual, the inner surface of the thermal sleeve 5 is
Because it comes into direct contact with the supplied liquid (supplied water) and reaches that temperature, if the supplied liquid amount or temperature changes suddenly due to changes in operating conditions, etc. In order to prevent thermal stress from occurring and the expansion and contraction of SeiFend 3, which has sufficient pressure resistance, from affecting the thin thermal sleeve 5, the installation of the thermal sleeve 5 is done to reduce the stress generated in the parts, etc. There are problems such as an abnormally large size.

The present invention effectively solves the problems of the prior art, and aims at alleviating temperature changes and reducing thermal stress in the vicinity of the connecting point between the safe end and the thermal sleeve. It is something.

"Means for solving the problem" The liquid supply piping consists of a plurality of thermal sleeves arranged at relative intervals in the radial direction on the inner surface of the Sayfend, which is connected to the single pipe section on the low temperature side. It is assumed that
For the liquid supply, the position of the cylindrical hollow part between the plurality of thermal sleeves is shifted to the lower temperature side than the middle cylindrical hollow part between the outermost thermal sleeve and the safety end. It is assumed that this was an addition to the plumbing.

"Effect J: When a low-temperature supply liquid is inserted into a single pipe, the temperature of the innermost thermal sleeve that is in direct contact with the supply liquid drops rapidly, but there are multiple cylindrical hollow parts on the outside. By doing so, Seifend et al. 1 is delayed and the temperature change becomes gentle, reducing the occurrence of thermal stress.

In the plurality of cylindrical hollow parts, as the position of each end on the low temperature side becomes radially inward, the temperature gradient between the Seifend and the thermal sleeve in the vicinity is shifted toward the low temperature side. tends to be similar in the radial direction and in the longitudinal direction of the tube, reducing the unevenness of the temperature distribution.

"Embodiment" Hereinafter, an embodiment in which the liquid supply piping according to the present invention is applied to the water supply system piping of a boiling water reactor will be described based on FIG. 1.

In this embodiment as well, a single pipe section 4 for water supply is connected to the nozzle 2 described above via a safe end 3, but a plurality of (first and second
) thermal sleeves 5A and 5B are integrally arranged concentrically.

A first cylindrical hollow part 6 is formed between the safe end 3 and the first thermal sleeve 5A located on the outside.
The low-temperature side end (the left end in FIG. 1) of the second cylindrical hollow part 6B formed between the thermal sleeves 5A and 5B is connected to the second cylindrical hollow part 6B. The second cylindrical hollow portion 6B is set to be slightly shifted toward the low temperature side.
The low-temperature side end is formed in a tapered shape slightly slanting radially outward.

Further, the position of the inner end of the first thermal sleeve 5A is set to be slightly inward than the inner wall surface of the reactor pressure vessel l, and the position of the inner end of the second thermal sleeve 5B is The inner end is connected to a water supply header or the like to supply dispersed water (liquid supply) into the furnace.

The material of each part is, for example, the nozzle 2 is made of low alloy steel, the safe end 3 and the single tube part 4 are made of carbon steel, and the thermal sleeve 5 is made of carbon steel.
A and 5B are set like austenitic stainless steel.

However, when the reactor is operated at a constant output, there is no change in the amount of water supplied from the single pipe section 4.
The temperature of the stagnant water in the second cylindrical hollow portions 6A and 6B is between the feed water temperature (for example, 190 to 210°C) and the furnace temperature (for example, 289°C), and the temperature in the longitudinal direction of the Seifend 3 is Due to the dispersion and attachment of both thermal sleeves 5A and 5B, the temperature distribution near the base becomes gentle.

In addition, if we consider that during the initial stage of reactor operation or when the output suddenly rises, low-temperature feed water rapidly flows into high-temperature stagnant water and replaces it, as shown by the arrow in Figure 1, When the water supply passes through the single pipe section 4, the safe end 3, and the second thermal sleeve 5B in order, the temperature of the water supply drops rapidly at the point where it is in direct contact with the water supply. The temperature change in the first thermal sleeve 5A between the portions 6A and 6B is delayed and becomes gradual. Furthermore, temperature changes also occur gradually in the welded portion W between the nozzle 2 and the safe end 3 located on the outside.

As shown in FIG. 1, both cylindrical hollow parts 6A and 6B
The installation of the first thermal sleeve 5A caused the base of the first thermal sleeve 5A to shift toward the inside of the reactor pressure vessel I, compared to the base of the second thermal sleeve 5B. Depending on the position, the tendency of the temperature distribution imparted to the safe end 3 and both thermal sleeves 5A and 5B shows an approximate tendency to gradually increase toward the outside in the radial direction and the inside of the container. Become a thing,
This reduces the occurrence of thermal stress.

On the other hand, FIGS. 2 and 3 show other embodiments of the liquid supply piping according to the present invention, and in the example shown in FIG. In the example shown in FIG. 3, the first cylindrical hollow portion 6A is located on the lower temperature side. The manufacture and installation of the Seifend 3 and the Double-Mulsleeves 5A and 5B are mainly designed with workability in mind.

``Effects of the Invention'' As explained above, in the liquid supply piping according to the present invention, a plurality of thermal sleeves are arranged inside the safe end to form a plurality of stagnation areas. When the temperature of the supplied liquid changes rapidly, the temperature change in the safe end, thermal sleeve, nozzle welding part, etc. can be made gentle to alleviate the occurrence of thermal stress. Also,
In the plurality of cylindrical hollow parts, the position of each end on the low-temperature side is shifted toward the low-temperature side as it becomes radially inward, so that the temperature gradient in the vicinity of the safe end is radially outward and downstream of the liquid supply. It shows a gradual trend of increasing gradually,
This has the effect of reducing unevenness in temperature distribution and suppressing the occurrence of thermal stress.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts showing one embodiment of the liquid supply piping according to the present invention, FIGS. 2 and 3 are cross-sectional views showing other embodiments of the liquid supply piping, and FIG. FIG. 2 is a sectional view showing a conventional example of liquid supply piping. 1... Reactor pressure vessel, 2 - Nozzle, 3... Seifend, 4... Single pipe section for water supply (single pipe section), 5A... 1st
Thermal sleeve, 5B...Second thermal sleeve, 6A...
...First cylindrical hollow part, 6B... Second cylindrical hollow part, W. - Welded part. Applicant Ishikawajima Harima Heavy Industries Co., Ltd.-8=

Claims (1)

[Claims] 1. A liquid supply pipe comprising a plurality of thermal sleeves arranged at relative intervals in the radial direction on the inner surface of a safe end connected to a single pipe portion on the low temperature side. 2. The position of the cylindrical hollow part between multiple thermal sleeves is
2. The liquid supply piping according to claim 1, wherein the liquid supply piping is disposed to be shifted toward a lower temperature side than the middle cylindrical hollow portion between the thermal sleeve at the outermost position and the safe end.