JPS6237360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a monitoring device for a low-pressure core spray system of a boiling water nuclear reactor.

Low-pressure core spray system of boiling water reactor (hereinafter referred to as
LPCS (abbreviated as LPCS) operates at a pressure below the reactor pressure of around 30 atm, and is operated by LPCS pumps when there is a risk of loss of reactor water and core cooling function due to a rupture in the reactor cooling piping, etc. This is a core cooling system whose purpose is to secure the coolant inside the reactor and cool the reactor core by spraying water in the suppression pool onto the upper part of the reactor core. Therefore, this device is extremely important for ensuring the safety of the nuclear reactor, and its health is required to be accurately monitored at all times.

Therefore, in the past, measurement signals obtained from indication/measuring instruments such as valve open/close status indicators, pump operation status indicators, pressure gauges, flow meters, etc. installed in each part of the LPCS were transmitted to lamp-type indicators on the central control panel. The LPCS was monitored by giving the signal directly to the pointer-type display and displaying it, which was then monitored by the operator. However, since the above-mentioned lamp-type indicators or pointer-type indicators are generally distributed on the control panel, the operator's attention is divided when monitoring them, making it difficult to monitor quickly and accurately. Otherwise, there is a risk of misunderstanding the display status or erroneous connection. In addition, the flow rate of the LPCS is measured based on a flowmeter installed in the LPCS piping, but as described later, this flowmeter is installed in the LPCS piping between the check valve and the branch point of the test piping. Therefore, if the test valve in the test pipe is open, this flow meter may not indicate the actual LPCS core spray flow rate.

The present invention was made in consideration of the above circumstances, and
The purpose is to comprehensively process signals obtained from various valve open/close status indicators, pump operation status indicators, flowmeters, and other indicating/measuring devices placed in the LPCS system using an electronic computer.
A low-pressure core spray system monitoring device that can detect the actual core spray flow rate, quickly and accurately monitor the operating status of the LPCS, and notify operators of any abnormalities. It is about providing.

The details of the present invention will be explained below based on embodiments shown in the drawings. FIG. 1 is a schematic diagram of an LPCS to which the present invention is applied. During LPCS operation, the water stored in the suppression pool 1 has a pump suction valve 2, an LPCS pump 3, a check valve 4, an injection valve 5, a testable check valve 6, a manual isolation valve 7, etc. It is sprayed from a spargeer 9 installed at the top of the reactor core via an LPCS pipe 8. Injection valve 5
A test pipe 11 having a test valve 10 branches off from the LPCS pipe 8 on the upstream side, and is connected to the suppression pool 1. In addition, the bypass valve 1 is connected to the LPCS piping 8 downstream of the check valve 4.
A minimum flow bypass line 13 with 2 branches, which is connected to the test line 1 downstream of the test valve 10.
Connected to 1. The pump suction valve 2 and the manual isolation valve 7 are normally open, but the injection valve 5 is normally closed and is opened only during LPCS operation. Further, the test valve 10 is always closed, but is opened only when testing the LPCS pump. Further, the bypass valve 12 is also normally closed, but is opened when there is a possibility of the pump overheating due to overload, thereby preventing the pump from overheating. Among the above valves, pump suction valve 2,
The injection valve 5, the testable check valve 6, the manual isolation valve 7, the test valve 10, and the bypass valve 12 are each provided with an open/close state indicator 14a, 14b, ~14f, and the LPCS pump 3 is provided with an operating state indicator 14a, 14b, ~14f. An indicator 15 is provided. Furthermore, pressure gauges 16a and 16b are installed upstream and downstream of the check valve 4, and a pipe 11 of the piping 8 between the check valve 4 and the injection valve 5 is installed.
A flow meter 17 is installed upstream of the branch point.

FIG. 2 is a diagram showing the configuration of a monitoring system, which is the main part of the present invention, coupled to the LPCS configured as described above. As is clear from this FIG.
f, 15, 16a, 16b, 17 are signal converters 2
1a, 21b to 21f, 21g, 21h, 21
Signal cable 22 with i and 21j interposed in the middle
a, 22b, ~22f, 22g, 22h, 22
It is connected to the input end of an electronic computer 23 via i and 22j, and a cathode ray tube display (hereinafter abbreviated as CRT) 24 is connected to the output end of the electronic computer 23. Each measurement signal generated by each of the above-mentioned indicating/measuring devices is amplified and converted by a group of signal converters 21a to 21j, and then processed by an electronic computer 23.
The operating status of the LPCS is monitored and the actual core spray flow rate is sensed. electronic computer 23
The results of the processing are displayed on the screen of the CRT 24 and notified to the operator.

FIG. 3 is a block diagram showing a program for carrying out processing in the electronic computer. This third
As shown in the figure, during the operation of the LPCS, the open/close state signals 31a to 31f from the valve open/close state indicators 14a to 14f are checked by a decision block 32, and each valve is in a normal state during the LPCS operation. It is verified whether it exists or not. If there is a valve that is not in a normal state, the message will be
Displayed on the CRT 24 to notify the operator of valve status abnormalities. Further, the operating state instruction signal 33 from the LPCS pump operating state indicator 15 is examined in a decision block 34 to verify whether the pump 3 is in operation. If the pump 3 is not in operation, it is determined that the pump 3 is at fault, and a message thereof is displayed on the CRT 24. Additionally, the pump discharge pressure signal 35 from pressure gauge 16b is examined at decision block 36 to verify that the pump discharge pressure is within a specified normal range. The flow signal 37 from the flow meter 17 is taken as representative of the actual spray flow rate only when the pump discharge pressure is within the normal operating range, the pump 3 is also running, and the test valve 10 is present. Otherwise, water cannot be sprayed into the core, so the spray flow rate is set to zero. In addition, even though each valve is in the normal state during LPCS operation and the LPCS pump 3 is in operation, if the pump discharge pressure is not within the specified normal range, the LPCS piping may be ruptured, blocked, or It is determined that an abnormality such as a leak has occurred, and a message notifying the piping abnormality is displayed on the CRT 24. For example, the display on the CRT24 is "Injection valve open"
This is done through messages such as ``High pump discharge pressure'' and ``LPCS piping error.''

In this way, with this system, abnormalities such as incomplete operation of the LPCS due to an open valve that should be closed, or incorrect indication of core spray flow rate due to an open test valve, are immediately notified to the operator. This allows operators to easily check the operation of the LPCS.

Furthermore, monitoring of the open/close status and functions of various manual valves that are not equipped with open/close status indicators can be easily performed by manually inputting them at the end of periodic inspections, etc. Become. In this way, the monitoring function of the operating status of the LPCS will be further strengthened, and the safety of the reactor in the event of an emergency can be improved.

As explained above, the present invention uses an electronic computer to
Open/close status of each valve of LPCS, pump operation status,
By comprehensively monitoring pump discharge pressure, flow meter signals, etc., LPCS operating status can be monitored and LPCS
We measured the core spray flow rate and reported the results.
It is designed to be displayed on a CRT screen. Therefore, according to the present invention, the operator
Not only can you easily and accurately monitor the operating status of the LPCS by simply observing the screen, but if an abnormality occurs, you can immediately know about the abnormal condition, and furthermore, you can prevent errors in the core spray flow rate. It is possible to provide an LPCS monitoring device that can eliminate instructions, etc. and improve the safety of nuclear reactors.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention. Figure 1 is a LPCS system diagram, Figure 2 is a schematic diagram showing the configuration of the monitoring system, and Figure 3 is a program inside the computer. FIG. 1...Suppression pool, 2...LPCS pump, 3...Pump suction valve, 4...Check valve, 5...
...Injection valve, 6...Testable check valve, 7...Manual isolation valve, 8...LPCS piping, 9...Spargeer, 1
0...Test valve, 11...Test piping, 12...
Bypass valve, 13... Minimum flow bypass piping, 1
4... Valve open/close status indicator, 15... Pump operation status indicator, 16a, 16b... Pressure gauge, 7...
...flow meter, 21 ... signal cable, 22 ... signal converter, 23 ... electronic computer, 24 ... cathode ray tube display (CRT).

Claims (1)

[Claims] 1. Various indicators and measuring instruments, such as open/close status indicators for various valves, pump operation status indicators, pressure gauges, flow meters, etc., provided in various parts of the low-pressure core spray system of a boiling water reactor. , an electronic computer that processes the measurement signals generated by these instruction/measuring instruments according to a predetermined program, and a cathode ray tube display that displays the results processed by this computer, By comprehensively processing various signals obtained from the indicating and measuring instruments, the computer determines abnormality in at least each part of the low-pressure core spray system and detects the spray flow rate of the above system, and uses the results as monitoring information to detect cathode rays. A low-pressure core spray system monitoring device, characterized in that it is configured to apply to a tube indicator. 2 The spray flow rate must be detected when the pump is in operation and when the pump discharge pressure is within the specified range.
The low-pressure core spray according to claim 1 is carried out by knowing the amount of water flowing through the spray system piping when the following three conditions are met: the test valve is closed. System monitoring device.