JPH1026306A - Secondary coolant system of pressurized water reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly discharge high-temperature water after a pressure-leakage test in a starting process, in a secondary coolant system of a pressurized water reactor. SOLUTION: A secondary coolant system 10 of a pressurized water reactor having a steam generator 1 through which a reactor coolant flows as a heating medium, a main feed water line 3 connected to the steam generator and a main steam pipe 5 extending from the ceiling part of the steam generator 1 has a construction wherein a cold water mixer 20 is attached to a blow line 11 communicating with the main steam pipe 5 through an on-off valve 13, on the main steam pipe 5 side of the on-off valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized water reactor, and more particularly to a drainage system for a secondary cooling system.

[0002]

2. Description of the Related Art In a pressurized water reactor, a liquid-phase reactor coolant always flows through a steam generator, heats feed water supplied to the steam generator, converts it into steam, and converts this into steam for driving a turbine. (Main steam). The system in which the reactor coolant circulates is called a primary cooling system, and the system in which feedwater and steam circulates is also called a secondary cooling system. FIG. 6 shows a main part of the secondary cooling system. In the figure, a main water supply line 3 communicates with a steam generator 1, and a main steam pipe 5 extends from a ceiling portion thereof and communicates with a steam turbine (not shown). Thus,
Considerable internal pressure is applied to the primary cooling system and the secondary cooling system during the operation of the reactor, so a pressure resistance / leakage test should be performed in the start-up process after the shutdown to ensure safe operation of the reactor. ing. In this test, the steam generator 1
And the main steam pipe 5 is filled with water, but becomes considerably hot water (about 170 ° C.), and is discharged or blown for normal operation after the test is completed. For this, cooling water (about 90 ° C.) is introduced from the main water supply line 3 into the steam generator 1 and the on-off valve 7
The high-temperature water in the steam generator 1 and the main steam pipe 5 is extruded into the blow line 9 with the opening.

[0003]

The allowable design temperature of the blow line 9 is as low as 150 ° C. This is because if the allowable design temperature is increased, the heat resistance temperature of the constituent members must be increased, which increases the manufacturing cost. Therefore, the allowable design temperature of the less necessary portion is not increased. Although the above-mentioned cooling water of about 90 ° C. also has a function of cooling high-temperature water, it takes a considerable time for the high-temperature water to reach a design allowable temperature or lower due to natural heat conduction. For this reason, the drainage of the high-temperature water must be waited until the high-temperature water becomes equal to or lower than the design allowable temperature. Therefore, an object of the present invention is to provide a secondary cooling system of a pressurized water reactor that can quickly discharge high-temperature water from a secondary cooling system after a pressure resistance / leakage test.

[0004]

According to the present invention, there is provided a steam generator through which a reactor coolant flows as a heating medium, a main water supply system connected to the steam generator, and a steam generator. The secondary cooling system of the pressurized water reactor having a main steam pipe extending from the ceiling of the generator, further comprises a blow line connected to the main steam pipe via an on-off valve, and a main steam pipe from the on-off valve. A cold water mixer is attached to the side.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same portions are denoted by the same reference numerals throughout the drawings including the drawings related to the above-described conventional device. First, referring to FIG. 1, a main water supply line 3 is connected to a steam generator 1 constituting a secondary cooling system 10 of a pressurized water reactor. Although not shown, the main water supply line 3 is provided with a water supply pump, a water supply heater, a deaerator, and the like, and communicates with the condenser. A main steam pipe 5 extends from the ceiling of the steam generator 1 and communicates with a steam turbine (not shown) and further with a condenser, thereby constituting a water supply / steam circulation system as a whole. According to the present invention, a blow line 11 is connected to the main steam pipe 5, and an on-off valve 13 is provided on the blow line 11. The on-off valve 13 is closed during normal operation of the reactor, but a chilled water mixer 20 is provided on the main steam pipe 5 side, and a chilled water supply line 17 having an on-off valve 15 is connected to a degassed water source (not shown). I'm in contact. Another blow line 18 is connected to the lower part of the steam generator 1, and a valve 19 is provided.

FIGS. 2 and 3 show a detailed structure of the chilled water mixer 20. FIG. The chilled water mixer 20 is composed of a casing 21 having a cylindrical outer shape and a porous central inner pipe 23. The central inner pipe 23 is formed with a number of holes 25 distributed inside the casing 21. In particular, as shown in FIG. 3, the pipe of the chilled water supply line 17 is opened in the tangential direction of the casing 21, but in this chilled water mixer 20, the pressure of the chilled water in the chilled water supply line 17 is reduced by the pressure of the hot water in the central inner pipe 23. Since the height is higher, it is not essential that the opening direction be tangential, and the opening direction may be in communication with the annular space 27 outside the central inner pipe 23.

[0007] In the above configuration, after the pressure resistance / leak test is completed in the start-up process of the pressurized water reactor, the steam generator 1 and the main steam pipe 5 are filled with high-temperature water.
In order to discharge this high-temperature water, about 90
C. Cooling water is injected into the steam generator 1. Since the main water supply line 3 is opened at the middle of the height of the steam generator 1, the high-temperature water at the top is pushed out to the main steam pipe 5, and the high-temperature water in the main steam pipe 5 is supplied to the cold water mixer 20. It is pushed out to. On the other hand, the high-temperature water in the lower part of the steam generator 1 is pushed out from the blow line 19 in which the valve 18 is opened. Simultaneously cold water mixer 2
0, low-temperature degassed water is supplied at a relatively high pressure from a cold water supply line 17 in which the on-off valve 15 is opened.
It is injected into hot water through the third hole 25. Therefore, when the high-temperature water and the low-temperature deaerated water are mixed and the temperature becomes lower than the design allowable temperature, the thermometer 12 detects this and sends a signal to the on-off valve 13. The on-off valve 13 is opened in response to the temperature signal, and the mixed water is discharged through the blow line 11.

Although the above-described cold water mixer 20 uses the porous central inner pipe 23, the cooling of the high-temperature water by the same mixing can be performed by using the cold water mixer 120 as shown in FIGS. Done. In the chilled water mixer 120, a tube of the chilled water supply line 17 is opened in a cylindrical casing 121 in a tangential direction. In this way, the low-temperature degassed water supplied from the cold water supply line 17 enters the casing 121, forms a swirling flow, and is forcibly mixed with the high-temperature water. When the mixing is completed, the on-off valve 13 opens and drainage starts, but the extrusion of hot water and the supply of deaerated water continue,
Mixing and discharge continue.

[0009]

As described above, according to the present invention, when discharging the high-temperature water after the pressure resistance / leakage test in the start-up process of the pressurized water reactor, the cold water provided at the joint between the main steam pipe and the blow line is used. High temperature water from the steam generator and main steam pipe and low temperature degassed water are forcibly mixed by the mixer, so the temperature of the discharged high temperature water drops quickly, so the discharge from the blow line is performed in a short period of time. be able to.

[Brief description of the drawings]

FIG. 1 is a partial system diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing main components of the embodiment.

FIG. 3 is a plan sectional view showing main components of the embodiment.

FIG. 4 is a perspective view showing an alternative example of the main constituent members of the embodiment.

FIG. 5 is a plan sectional view showing the alternative example of the main constituent members of the embodiment.

FIG. 6 is a partial system diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam generator 3 Main water supply line 5 Main steam pipe 10 Secondary cooling system 11 Blow line 12 Thermometer 13 On-off valve 15 On-off valve 17 Cold water supply line 20 Cold water mixer 21 Casing 23 Central internal pipe 25 Hole 27 Annular space 120 Cold water Mixer 121 Casing

Claims (1)

[Claims] 1. A pressurized water having a steam generator through which a reactor coolant flows as a heating medium, a main water supply system connected to the steam generator, and a main steam pipe extending from a ceiling of the steam generator. In a secondary cooling system of a nuclear reactor, a pressurized water type characterized in that a chilled water mixer is provided on the blow line connected to the main steam pipe via an on-off valve, and on the main steam pipe side of the on-off valve. Reactor secondary cooling system.