JPS62132199A - Connecting structure of exhaust pipe for main-steam relief safety valve of nuclear reactor container - 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] [Field of Application of the Invention] The present invention relates to a main steam safety relief valve exhaust pipe for a boiling water reactor containment vessel, and in particular to a connection of a main steam safety safety valve exhaust pipe suitable for drastically reducing thermal reaction force. Regarding structure.

[Background of the invention]

Conventional known examples will be explained below.

Figure 4 shows an overall view of the boiling water reactor containment vessel. The reactor containment vessel main steam relief safety valve exhaust pipe piping 1 is used to release the main steam pipe 3 when the pressure inside the reactor pressure vessel 2 rises transiently.
It is installed for the purpose of guiding a part of the main steam to the sparger 6 in the pressure suppression chamber pool underwater 5 through the main steam relief safety valve 4 installed in the pressure suppression chamber. Further, the main steam relief safety valve exhaust pipe 1 is led from inside the reactor containment vessel dry well 11 containing the reactor pressure vessel 2 through the bellows 9, through the diaphragm floor 10, and into the pressure suppression chamber 12. The bellows 9 of the diaphragm floor 10 penetrating portion absorbs the forced displacement of the exhaust pipe due to loads such as high temperature and high pressure of the main steam flowing inside the exhaust pipe, and furthermore, the bellows 9 of the diaphragm floor 10 penetrates
and the pressure suppression chamber 12.

In addition, as shown in FIG. 3, the exhaust pipe 1 is provided with a number of pipe supports 14 in order to ensure the strength of the exhaust pipe 1 against pipe reaction forces due to mechanical loads such as earthquake loads within the pressure suppression chamber 12. Supported. Furthermore, the exhaust pipe piping 1 is designed to release the thermal expansion of the exhaust pipe piping 1 due to the high temperature main steam flowing inside the exhaust pipe piping 1, and to relieve the thermal stress of the exhaust pipe piping 1.
has many curved parts.

Further, the exhaust condition g1 is connected to the top opening of the sparger 6 by welding, and the sparger 6 is fixed to the reactor containment vessel bottom mat 13 via a lower sparger support 7 and an anchor bolt 8.

In addition, the piping route design for the main steam relief safety valve exhaust pipe 1 is performed in the following manner.

(i) Piping support 14 layout design for reinforcement against piping reaction force due to earthquake load and mechanical load.

(ii) A piping route design in which the exhaust pipe piping 1 is detoured by using a bent pipe in order to release the axial thermal expansion of the piping due to high temperature.

(iii) The exhaust pipe piping 1 is restrained by the piping support 14 in the above (i), and the thermal stress caused by the main steam in the piping becomes severe, so the design balances the above (i) and (ii).

This structure has the following problems.

(a) A balanced design is required between the piping support arrangement design for seismic loads and mechanical loads, and the piping route design for mitigating the thermal stress of the piping due to support restraint, which increases the number of design steps.

(b) In order to reduce the thermal stress due to the restriction of the piping support, bent pipes are provided in the piping and the piping route is made with a large detour, which increases the number of man-hours and costs.

(c) In (b) above, since the piping route is largely detoured to avoid interference with other internal structures of the container, the space inside the container is reduced and cannot be used effectively.

In order to solve the problems of the prior art as described above, drastic structural measures are required.

[Purpose of the invention]

An object of the present invention is to provide a main steam safety safety valve exhaust pipe structure for a boiling water reactor containment vessel, which has a structure in which pipes are overlapped to drastically reduce stress due to thermal load.

[Summary of the invention]

The present invention solves the problem of an increase in the number of piping supports in the conventional main steam relief safety valve by detouring the piping to alleviate the thermal stress.
The joint with the top opening of the pipe uses a simple overlapping structure of pipes.

According to the present invention, the piping axis direction of the sparger 6 joint part of the exhaust pipe piping 1 is not restricted, so thermal stress can be drastically reduced, and the detour of the piping and the accompanying piping support 14 can be reduced.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, in this embodiment, the exhaust pipe 1 is fitted inside the top opening of the sparger 6 with a slight gap, and the exhaust pipe 1 and the sparger 6 are arranged in the axial direction of the pipe. Each independent displacement is possible.

In FIG. 2, the exhaust pipe piping 1 in the pressure suppression chamber 12 below the diaphragm floor 10 does not take a detour.
It passes through the straight, shortest piping route and is connected to the sparger 6.

For this reason, 1 the exhaust pipe piping 1 and the sparger 6 in the present invention
Since the axial direction of the exhaust pipe 1 is not constrained at the joint, no thermal stress is generated due to thermal expansion of the exhaust pipe.

In addition, a small gap is provided at the joint between the exhaust pipe 1 and the top opening of the sparger 6, and the pipes are overlapped. Since the amount of leakage from this gap is very small compared to the amount of steam blown out from the mouth, there are no particular problems in terms of structure and maintenance.

(Effects of the Invention) Since the present invention is configured and operates as described above, the following effects can be achieved.

(i) By making the exhaust pipe piping and the top of the sparger overlap and fit together, the shortest piping route is possible without the need for a detour piping route to reduce thermal stress in the piping, and a significant amount of material can be saved. It is possible to reduce costs as a result of this reduction.

(n) From (i) above, there is no detour route for the low thermal stress region of the piping, and accordingly, the number of piping supports can be reduced.

(iii) From the above (i), the space inside the container can be secured by the piping bypass route, and the workability of the installation work inside the container can be improved.

[Brief explanation of drawings]

Fig. 1 is a detailed view of the boiling water reactor containment vessel main steam relief safety valve exhaust pipe using the present invention, Fig. 2 is a longitudinal sectional view of the boiling water reactor containment vessel using the present invention, and Fig. 3 4 is a perspective view of the main steam relief valve exhaust pipe of a conventional boiling water reactor containment vessel, and FIG. 4 is a vertical sectional view of the conventional boiling water reactor containment vessel. 1...Exhaust pipe piping, 2...Reactor pressure vessel, 3...
・Main steam pipe, 4... Main steam relief safety valve, 5... Pressure suppression chamber pool water, 6... Sparger, 7... Sparger support, 8... Anchor bolt, 9... Bellows, 10... Diamond wall 11 floor, 11... Reactor containment vessel dry well, 12... Reactor containment vessel pressure suppression chamber, 13... Reactor containment vessel bottom mat, 14
...Piping support.
,--11, Agent Patent Attorney
Katsuo Ogawa □ 1 Mo1 figure Leopard 2 figure Yu 3 figure

Claims (1)

[Claims] 1. In the main steam relief safety valve exhaust pipe, which consists of the reactor containment vessel main steam safety valve exhaust pipe piping and the main steam relief safety valve spargeer installed underwater, the connection between the exhaust pipe piping and the safety valve spargeer is made by overlapping the pipes. A connection structure for a reactor containment vessel main steam relief safety valve exhaust pipe, characterized by having a mating structure.