JPS58180875A - Deformation-preventing method for valve - Google Patents

Abstract

PURPOSE:To prevent leakage from occurring at a valve seat of a water-steam two-phase boundary valve, by removing a plastically deformed part of the valve seat by heating the valve seat before fitting the valve into a plant. CONSTITUTION:A shut-off valve 10 provided in a residual heat recovering (RHR) system comprises a stem 14 inserted in a body 15 and a valve body 17 provided at a lower end part of the stem 14. In normal operation of a boiling water reactor, the valve body 17 makes contact with the valve seat 16, thereby preventing water B and steam A from making contact with each other. In a manufacturing step of the valve 10, a valve seat part of the valve 10 is heated to apply a heat load under the same condition as that in the operation of the plant. Then, the part is subjected to sliding machining, thereby removing the plastically deformed part. Accordingly, the thermal strain generated at a part subjected to a heat load in the succeeding use of the valve is made very little.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to countermeasures against valve seat leakage of a water-steam boundary valve in μ, R, B, and steam vertical and narrow modes.

The steam forging of the reactor cooling system (hereinafter referred to as RCIC) during reactor isolation of a boiling water reactor will be explained with reference to FIG. During reactor isolation, steam generated in the reactor pressure vessel 1 is guided from the turbine inlet pipe 3 connected to the main steam pipe 2 to the CIC turbine 4 and then to the RCI
The turbine-driven pump 5 connected to the C turbine 4 is driven, and the pressure is ejected into the press 7 pool 13 through the turbine discharge pipe 7. Also, the water in the condensate storage tank 14 is supplied to B, CIC by the turbine-driven pump 5.
It is injected into the reactor core within the reactor pressure vessel 1 through the inlet and inlet pipes 6.

On the other hand, in order to condense the steam in the residual heat removal system (hereinafter referred to as RHR), the reactor generated steam is guided through the turbine inlet piping 3 to the RHR heat exchanger 11 through the Ia valve 10 and condensed into the RCICI! f. Return to the inlet pipe 6 and inject into the reactor core.

AOFi is an air operated valve, HO is a hydraulically operated sea bream valve, MO is an electric sea bream operated valve, and PCV is a pressure A14 regulating valve.

The reactor pressure vessel 1 is placed in the dry well 15fi.

Reactor N operation A has turbine population valve 8 and shutoff valve 10.
is closed i1 this fit, RHR hot father chivalry device population distribution wealth 9
And the inside of the RHR piping 16 is sealed with water to prevent water hammer when starting the RHR. Therefore, 10 ri of passing valves connect 1 tllll of upper water (approximately 280 tons) and downstream normal temperature water (approximately 500 tons). Therefore, i
The A valve 10 is a water-shiki two-phase boundary cell.

The shrub-shaped shutoff valve 10 has a diameter of approximately 280 mm as shown in FIG. 2 VC.
In order to separate steam A at about 50C and water B at about 50C, the opening and exit of the valve has a large stroke. As a result, the valve seat portion becomes I-shaped due to thermal distortion, and valve seat leakage may occur.

When a leak occurs, the following gaps will occur.

l) Temperature and pressure inside the HR pipe increases.

In this case, an alarm will be issued due to the temperature straight line and pressure resistance installed in the R and HR snow pipes 16, so each time the RH pipe 1
6 yen high temperature water ttw must be discharged into the pressure pool 13.

21 RH general - 111f16 is a friend of steam,
When the Hf'L pump is started, water hammer due to the vapor phase may occur.

An object of the present invention is to provide a liquid-gas two-phase boundary valve that can prevent valve seat leakage of the water-steam two-phase bulk boundary valve.

The present invention simulates the heat cycle of a plant in a liquid-gas two-phase boundary valve, applies a heat cycle load at the time of valve operation, and then applies an initial strain -+c from a machine 710. In order to eliminate this problem, Kawasaki has reduced the diamond shape of the valve seat due to thermal distortion to prevent valve seat leakage.

A simple embodiment of the present invention will be explained with reference to FIG.

R) The 11 series quick-release valve 1G has a stem 14 inside the body 15.
is inserted, and a valve body 17 is provided at the lower end of the stem 14. The stem 14 is connected to seven cutout units 13 for driving. #! During normal operation of a water-cooled nuclear reactor,
The valve body 16 retracts from contact with the valve seat 16 to prevent water B and steam AcD from coming into contact with each other.

In addition, measures to prevent the steam 1'a of the quick-cut valve 10 are heated at the stage of pulp production by heating the valve seat S of the quick-cut valve 1G to apply the same heat load as during plant operation. KJ: Permanently deforms the valve seat of the shutoff valve 100 on the surface where the shutoff valve 10 is attached to the CIC. Next, perform a sliding process on this part, and! @The deformed part t-removes. As a result, the thermal distortion of the portion subjected to the heat load will be extremely small when the valve is used next time. By using the valve in this state, steam leakage from the valve seat can be prevented.

According to the present invention, the following effects can be obtained.

1) RCIC1411 high @ steam and RHRill water (
Steam leakage can be prevented by applying a heat load to the valve seat part of the shutoff valve that cuts off the part (at room temperature) during the manufacturing stage, and then subjecting it to a sliding process.

2) Since steam leakage can be prevented by item 1), RCI
The high-temperature, high-pressure steam on the C side does not leak to the R)IRIiil, eliminating the need for warnings and draining of water due to low pressure.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the reactor 14Ilii cooling system, and Fig. 2 is a detailed IP structure diagram of the appropriate wT square used in the system of Fig. 1. 1... Pushi reactor pressure gain, 3... Turbine inlet side piping, 4... RCIC turbine, 5... CIC pump, 6... RCIC inlet pipe, 7... Turbine lower ft Side lightning, 1o...Shutoff valve, 11...Le HR, heat exchanger, 14...Stem, 15...Body, 16...Valve J! i! ik,, 1 agent, Fjm person A, I14 Ming＾゛゛worry. 5.・)′

Claims (1)

[Claims] 1. A method for preventing deformation of the valve, which includes a body having a valve seat inside, a stem that extends into the body, and a valve body that is attached to the stem and faces the valve seat. A method for preventing deformation of a cell, characterized in that, before installing the cell in a plant, the valve seat is heated to plastically deform it, and the plastically deformed portion is removed.