JP2000346978A - Pressurizer gas phase disappearance automatic judgment device of pressurized water reactor plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make accurately graspable the gas phase disappearance time point in an operation of the gas phase disappear in the pressurizer of a pressurized water reactor. SOLUTION: The pressurizer gas phase disappearance automatic judgment device of a pressurized water reactor plant provided in a pressurizer 1, communicating with the primary coolant system 3 of a pressurized water reactor at the lower part, provided with a heater 9 in the lower part and a spray nozzle 11 on the ceiling, is provided with an acoustic detector 41 on a sampling line 25 connecting to the top of the pressurizer 1 and extending outward, and a frequency analyzer 43 receiving sound output of the acoustic detector 41 in the constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurizer for a pressurized water nuclear power plant, and more particularly to an apparatus for automatically determining the disappearance of a gas phase region.

[0002]

2. Description of the Related Art In a pressurized water nuclear power plant, a reactor coolant circulation loop connected to a reactor vessel, a so-called primary coolant system, comprises a steam generator, a coolant pump, and piping connecting these components. Pressurizers are used to control the pressure of the primary coolant and keep it in the liquid phase.
Pressurizers are also used to monitor the amount of water in the primary coolant system. FIG. 3 conceptually illustrates the relationship between the primary coolant system and the pressurizer. The pressurizer 1 is in the form of a vertical pressure vessel, and the lower part is connected to the piping of the primary coolant system 3. During normal operation, the pressurizer 1 is formed such that a liquid phase part 5 made of a primary coolant and a gas phase part 7 are formed inside and below the inside of the pressurizer. Explaining the basic function of the pressurizer 1, the heating part of the heater 9 is provided so as to be immersed in the liquid phase part 5, and when this is heated, the evaporation of the liquid phase part 5 is promoted, Pressure rises. The increased pressure is transmitted to the primary coolant system 3 to increase the pressure in the system. On the other hand, when the relatively low-temperature primary coolant of the primary coolant system 3 is guided and sprayed from the spray nozzle 11 provided on the ceiling to the steam of the gas phase portion 5, a part of the steam is condensed and the pressure is reduced. descend. This pressure drop is also transmitted to the primary coolant system 3 to reduce the pressure in the system. still,
The primary coolant is usually light water and a compressible fluid,
It expands as the temperature rises. A volume control tank 13 is provided to control the extraction flow rate 15 and the filling flow rate 17 for the purpose of mitigating these effects.

[0003] When the plant is shut down, it is necessary to cool the coolant in the pressurizer 1, so that the liquid level is raised and the gas phase 7 is extinguished. More specifically, as shown in FIG.
7 to increase the amount of coolant in the primary cooling system 3. Thereby, the amount of coolant in the pressurizer 1 increases, and the liquid level rises. When the gas phase 7 disappears, the interior of the primary cooling system 3 including the pressurizer 1 becomes full, and the subsequent internal pressure change is determined by the amount of coolant in the system. The form changes. Therefore, it is necessary to accurately detect the disappearance of the gas phase part 7 in order to safely perform a series of plant operation stop operations. On the other hand, when the gas phase portion 7 is eliminated, there is no gas condensed by spraying, so that even if the low-temperature coolant is sprayed, the pressure hardly changes. Focusing on this phenomenon, the gas phase portion 7 of the conventional pressurizer 1
As for the disappearance of the gas phase, the operator monitored the presence or absence of a change in the pressure in the system while appropriately performing a spraying operation. When the above-mentioned state occurred, it was determined that the gas phase had disappeared.

[0004]

However, the above-described method for determining the disappearance of the gas phase is based on the presence or absence of a pressure change due to the spray operation after the gas phase has disappeared. A time delay is likely to occur between them.
For this reason, if the filling of the coolant is continued as it is, the amount of the coolant in the primary coolant system 3 increases, and there is a fear that an excessive stress is generated. Accordingly, an object of the present invention is to provide a pressurizer gas phase disappearance automatic determination device for a pressurized water nuclear power plant that can detect the simultaneous disappearance of the gas phase part in the pressurizer gas phase part disappearance operation of the pressurized water reactor. I do.

[0005]

According to the present invention, in order to achieve the above object, according to the present invention, there is provided an automatic judging device for gas phase annihilation of a pressurized water reactor of a pressurized water nuclear power plant. In a pressurizer provided with a heater in the lower part in communication and a spray nozzle in the ceiling part, an acoustic detector is attached to a sampling pipe communicating outwardly to the uppermost part in the pressurizer and extending outward. A determinator including a frequency analysis device that receives the acoustic output of the acoustic detector is provided.

[0006]

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 technology. First, referring to FIG. 1, a primary coolant system 3 is not shown, but a steam generator connected to a reactor vessel, a coolant circulation pump, and high-temperature pipes and low-temperature pipes connecting these,
The lower part of a pressurizer 1 in the form of a vertical pressure vessel communicates with a crossover pipe or the like. During normal operation of the nuclear reactor, the pressurizer 1 is configured such that a liquid phase portion 5 made of a primary coolant is formed below the inside and a gas phase portion 7 is formed above the inside. The heating section of the heater 9 is provided so as to be immersed in the liquid phase section 5, and the spray nozzle 11 is provided on the other ceiling. The spray nozzle 11 communicates with a low-temperature pipe of the primary coolant system 3 through a spray water pipe 21, and the spray water pipe 21 is connected to the on-off valve 2.
3 is provided. When the on-off valve 23 is opened, a relatively low-temperature primary coolant is supplied to the spray nozzle 11 as spray water and sprayed into the gas phase section 7.

[0007] A sampling line 25 for sampling a vapor in the gas phase part 7 of the pressurizer 1 during operation of the reactor.
Open at the uppermost portion inside the pressurizer 1. The sampling line 25 is provided with an isolation valve 27 and is connected to a sample water treatment device (not shown), but the discharge port is connected to the volume control tank 13. Therefore, unused sample water and the like are returned to the volume control tank 13. Extraction line 29 connecting primary coolant system 3 and volume control tank 13
Is provided with an extraction amount control valve 31, and a similar filling line 3 is provided.
3 is provided with a filling amount control valve 35, a filling pump (not shown), and the like. Therefore, it will be apparent to those skilled in the art that the extraction flow rate 15 and the filling flow rate 17 are appropriately controlled. An acoustic detector 41 is provided adjacent to the sampling line 25, and its output line is connected to a frequency analyzer 43.
, And the frequency analysis device 43 further communicates with a display lamp 45 as a display means.

In the above-described configuration, the gas phase extinction operation as a part of the operation for stopping the operation of the reactor is performed by controlling the extraction amount so as to increase the flow rate difference (filling flow rate 17-extraction flow rate 15) as in the prior art. The valve 31 and the filling amount control valve 35 are controlled. By doing so, the amount of coolant in the primary coolant system 3 increases, and the increased coolant inevitably flows into the pressurizer 3 and the liquid level rises. If the isolation valve 27 is opened in advance, steam flows as the liquid level rises. During the flow of the vapor, the flow velocity is large, and the acoustic signal obtained by the acoustic detector 41 has a high frequency band dominant as shown in a region A of FIG. Then, when the gas phase portion 7 disappears and the coolant, which is a liquid, starts flowing, the flow velocity decreases, and the frequency decreases as shown in a region B. Then, the transition point from the area A to the area B is determined as the time point at which the gas phase part disappears.

[0009]

As described above, according to the present invention,
Since the acoustic signal emitted by the fluid flowing through the sampling line connected to the top of the pressurizer is detected by the acoustic detector, and the acoustic signal is analyzed in frequency to determine the type of the fluid, thereby determining the disappearance of the gas phase. It is possible to accurately determine the disappearance of the gas phase almost simultaneously. In addition, since the apparatus of the present invention can be additionally installed in a sampling line of a conventional pressurizer, it can be easily installed in an existing plant.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of an embodiment in which the present invention is applied to a pressurizer of a pressurized water nuclear power plant.

FIG. 2 is an operation explanatory view of the embodiment.

FIG. 3 is a system diagram around a pressurizer of a conventional pressurized water nuclear power plant.

FIG. 4 is an operation explanatory graph for explaining a problem of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressurizer 3 Coolant system 5 Liquid phase part 7 Gas phase part 9 Heater 11 Spray nozzle 13 Volume control tank 15 Extraction flow rate 17 Filling flow rate 21 Spray water pipe 23 Open / close valve 25 Sampling line 27 Isolation valve 29 Extraction line 31 Extraction amount control Valve 33 Filling line 35 Filling amount control valve 41 Sound detector 43 Frequency analyzer 45 Indicator light

Claims (1)

[Claims] 1. A pressurizer having a lower portion communicating with a primary coolant system of a pressurized water reactor and having a heater at an inner lower portion and a spray nozzle at a ceiling portion, wherein the lower portion communicates with the uppermost portion of the pressurizer. An acoustic detector is attached to an outwardly extending sampling pipe, and a determiner including a frequency analyzer for receiving an acoustic output of the acoustic detector is provided. Judgment device.