JPH04309896A - Water pump control device for steam generation plant - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of boiling water nuclear power plants, and particularly to feedwater pump control when the output is reduced due to selective control rod insertion.

0002

[Prior Art] The conventional technology of a water pump control device for a boiling water nuclear power plant is two T/D-RFPs and an M/D-R.
A plant having two FPs will be explained using FIG. 6 as an example.

[0003] In a boiling water nuclear power plant, steam generated by heat generated in a reactor core 2 formed in a reactor pressure vessel 1 is guided to a steam turbine 3 to perform work, and is operated in conjunction with the steam turbine 3. The generator 4 generates electricity, and the grid 5
It supplies electricity to. The steam that has done work in the steam turbine 3 is condensed in a condenser 6 and becomes water. This water is supplied as cooling water from the condenser 6 through the water supply pipe 7 into the reactor pressure vessel 1. That is, the pressure of the cooling water discharged from the condenser 6 is increased by the condensate pump, and then reaches the water supply pump. The water supply pumps are T/D-RFP11, 2 units and M
The M/D-RFP consists of 12 and 2 units, each of which is equipped with a minimum flow valve 13, but during normal plant operation, the M/D-RFP 12 and 2 units are stopped and the minimum flow is reduced. All valves 13 are also closed,
After the cooling water is pressurized by the T/D-RFPs 11 and 2, it is supplied into the reactor pressure vessel 1 .

[0004] The flow rate of cooling water supplied into the reactor pressure vessel 1 by the feedwater pump, that is, the feedwater flow rate, is controlled by a feedwater flow rate control device 100. That is, the feed water flow rate during normal plant operation is determined by the reactor water level signal 102 detected by the reactor water level detector 101, the feed water flow rate signal 104 detected by the feed water flow rate detector 103,
This is achieved by inputting the main steam flow rate signal 106 detected by the main steam flow rate detector 105, outputting the feed water flow rate request signal 107 through three-element control, and changing the opening degree of the control valve and the rotation speed of the RFP turbine 19. It is being said.

[0005] In such a plant, if a generator load shedding occurs in which the power station is disconnected from the grid 5,
The power load imbalance relay 20 detects this,
The steam control valve 21 is suddenly opened. Simultaneously with the sudden closing of the steam control valve 21, the turbine bypass valve 22 is suddenly opened. Furthermore, in order to avoid an event in which the neutron flux increases due to a steam flow mismatch due to the opening/closing characteristics of both valves, causing a reactor scram, the sudden closing of the steam regulating valve 21 is detected by a steam regulating valve sudden closing detector 23, which is a hydraulic pressure sensor. Based on the detection signal, the two recirculation pumps 15 are tripped, and the selected control rod 24 is inserted into the reactor core 2 to reduce the output.

At this time, the water supply pump control device 200:
The interlock shown in FIG. 6, that is, the output signal 201 of the steam control valve sudden closing detector 23 and the operation status signal 203 of the water supply pump are input to the determination circuit 204, and the T/D-RFP
, is in operation, and inputs the two signals to the delay time determiner 202. After a predetermined time, a trip signal 205 is output to the T/D-RFP, and the T/D - At the same time as tripping one RFP 11, a signal 206 is output to lock the switch connecting the motor and power source of the M/D-RFP 12 in the "open" state and prevent the pump from starting.

[0007] As described above, in response to a drop in main steam flow rate due to a sudden drop in output due to a recirculation pump trip and insertion of a selective control rod when a load shedding occurs in the power system,
Water pumps are automatically tripped to avoid turbine trips due to rising reactor water levels.

[0008]

[Problem to be Solved by the Invention] In conventional water supply control for steam generation plants, the feed water pump automatic trip interlock was applied only to avoid turbine tripping due to a rise in reactor water level during load shedding. If a selective control rod was inserted for any other reason and the reactor output decreased, there was a possibility that the water supply flow rate could not be reduced to match the output, causing the reactor water level to rise and causing a turbine trip.

[0009] In addition, in the conventional control device, only an interlock was used to trip one T/D-RFP and prevent the automatic activation of the M/D-RFP in order to cope with a decrease in output. By inserting the rod, T/
It has been difficult to deal with a case where the output drops below the flow rate that can be narrowed down by one D-RFP.

The present invention aims to solve the above problems.

[0011]

[Means for Solving the Problems] The present invention detects the insertion of a selective control rod to automatically trip the water supply pump even when the selective control rod is inserted for purposes other than load shedding. I decided to trip the .

[0012] Furthermore, in order to avoid unnecessary water pump trips, it is determined that the water supply flow rate, the water supply flow rate request signal calculated by the water supply flow rate control device, or the water supply pump flow rate has become less than the setting 1. , trip one water pump and at the same time prevent the standby pump from starting, and set 2.
It was determined that the following conditions had occurred, and the decision was made to trip the second water pump and at the same time start up the standby unit or suddenly open the minimum flow valve of the running water pump. Here, setting 1 is a value determined based on the lower limit flow rate that can be narrowed down with two water supply pumps, and setting 2 is a value determined based on the lower limit flow rate that can be narrowed down with one water supply pump.

Furthermore, in order to avoid an excessive drop in the pump trip reactor water level when the reactor water level is decreasing, the feed water pump It was designed to trip.

[0014]

[Operation] By determining that the selective control rod has been inserted and tripping the feed water pump, the rise in reactor water level can be suppressed even in the event that the selective control rod is inserted for reasons other than load shedding and the output is reduced. becomes possible.

Further, unnecessary pump trips can be avoided by outputting a feed water pump trip signal based on the feed water flow rate, the feed water flow rate request signal, or the pump flow rate and using the reactor water level as a determination condition. Furthermore, by setting the high reactor water level as a permission condition, it is possible to avoid pump trips when the reactor water level is decreasing.

[0016] Depending on the degree of decrease in the feed water flow rate, etc., the reactor can be stabilized by tripping the second feed water pump or rapidly opening the minimum flow valve of the running water pump to reduce the feed water flow rate. It becomes possible to suppress the rise in water level.

[0017]

[Embodiments] [Embodiment 1] A water supply pump control device according to the present invention is shown in FIGS. 1 and 2.

[0018] At a boiling water nuclear power plant, T/D-RFP
2 units 11a, 11b and 2 M/D-RFP units 12a,
12b, during normal reactor operation, T/
Water is supplied into the reactor pressure vessel 1 by two D-RFP units 11a and 11b.

The feedwater pump control device according to the present invention includes a selective control rod insertion request signal 108 outputted from the selective control rod insertion circuit 29, a feedwater flow rate signal 104, and a reactor water level signal 10.
2, T/D-RFP11a, 11b and M/D-RF
Operating status of P12a, 12b (running or stopped)
The signal is captured and the water pump is tripped using the logic shown in FIG. That is, the determination circuit 204 is a T/D-RFP.
It is determined that two units are in operation, the selected control rod insertion operation signal 108 is input, and the comparator 208 determines that the water supply flow rate signal 104 is smaller than the setting 1 in the setting device 207, and this state is set in the timer 209. T/D-RF continues for a period of time, and when the comparator 211 determines that the reactor water level signal 102 is higher than the set value 3 in the setting device 210.
At the same time as outputting the P1 unit selection trip signal 205, the M
/M/D-RFP activation prevention signal 2 for 2 D-RFPs
06 and shifts to one T/D-RFP operation.

Furthermore, the water supply flow rate signal 104 is sent to the setting device 213.
When the comparator 212 determines that the reactor water level is lower than the set value 2, this state continues for the time set in the timer 214, and the comparator 211 determines that the reactor water level is higher than the set value 3, the At the same time as outputting a trip signal 215 to the D-RFP, a two-M/D-RFP activation signal 216 is outputted to the M/D-RFP, and the M/D-RFP
Shift to operation of two RFPs.

Furthermore, during operation with only one T/D-RFP 11, the selected control rod insertion operation signal 108 is input, and the comparator 122 determines that the water supply flow rate signal 104 is smaller than the setting 2 in the setting device 121. This state continues for the time set in the timer 123, and when the comparator determines that the reactor water level is higher than the set value 3, the operating T/D-
At the same time as outputting a trip signal 215 to the RFP, a two-M/D-RFP start signal 216 is output to the M/D-RFP, and the operation shifts to two M/D-RFPs.

The same logic applies to a plant with three M/D-RFP water pumps. Further, instead of the water supply flow rate signal used for the determination, it is also possible to use a water supply flow rate request signal calculated by the water supply flow rate control device or a water supply pump flow rate signal.

[0023] In addition, in this embodiment, the determination of low water supply flow rate,
Although the reactor water level is determined in the feed water pump control device, it is also possible to perform this determination in the feed water flow rate control device and import the results into the feed water pump control device.

Furthermore, in this embodiment, the feed water pump is tripped when all of the following conditions are satisfied: the selected control rod insertion operation signal, the feed water flow rate is low, and the reactor water level is high. It is also possible to construct logic using conditions.

Furthermore, in this embodiment, the water supply flow rate is determined in two stages, but when the flow rate falls below the set value 1, the M/D-
It is also possible to simplify the system by shifting to operation of two RFPs.

[Embodiment 2] A water supply pump control device according to the present invention is shown in FIGS. 3 and 4.

In the first embodiment, when the water supply flow rate signal 104 falls below the set value 2 (set by the setting device 213), the second T/D-RFP is tripped and the operation shifts to two M/D-RFPs. However, it was possible to restrict the water supply to the reactor by rapidly opening the minimum flow valve (signal 217) of the operating T/D-RFP11b without tripping the second T/D-RFP. be.

The present invention is applicable to a plant where the water supply system is composed of three M/D-RFPs.
When the water supply flow rate falls below the set value 2 in the P1 unit operating state, this can be handled by suddenly opening the minimum flow valve of the M/D-RFP that is in operation.

Furthermore, as in the first embodiment, the water supply flow rate request signal calculated by the water supply flow rate control device or the water supply pump flow rate signal can be used instead of the water supply flow rate as the signal used for determination.

[0030] In addition, in this embodiment, the determination of low water supply flow rate,
Although the reactor water level is determined in the feed water pump control device, it is also possible to perform this determination in the feed water flow rate control device and import the results into the feed water pump control device.

Furthermore, in this embodiment, the feed water pump is tripped when all of the following conditions are satisfied: the selective control rod insertion operation signal, the feed water flow rate is low, and the reactor water level is high. It is also possible to construct a logic based on two conditions.

[0032]

[Effects of the Invention] According to the present invention, even if a selective control rod is inserted for reasons other than load shedding and the output suddenly decreases, the water supply pump can be tripped according to the value of the water supply flow rate. It becomes possible to reduce the water supply to the reactor pressure vessel to a flow rate commensurate with the output, and it is possible to avoid an event where the reactor water level rises and causes a turbine trip. Further, by tripping the pump according to the value of the water supply flow rate, etc., unnecessary water supply trips can be avoided.

Furthermore, according to the present invention, even if one water supply pump is tripped depending on the value of the water supply flow rate, if the water supply flow rate becomes too small, the second pump is subsequently tripped or the minimum flow valve is activated. By rapidly opening the reactor, it becomes possible to continue operating the reactor.

[Brief explanation of drawings]

FIG. 1 is a feed water pump control device for a steam generation plant according to the present invention.

FIG. 2 is an interlock diagram of a feedwater pump control device for a steam generation plant according to the present invention.

FIG. 3 is a feed water pump control device for a steam generation plant, which is another embodiment of the present invention.

FIG. 4 is an interlock diagram of a feed water pump control device for a steam generation plant, which is another embodiment of the present invention.

FIG. 5 is a diagram showing a conventional feed water pump control device for a steam generation plant.

FIG. 6 is an interlock diagram of the water pump control device of FIG. 5;

[Explanation of symbols]

100... Water supply control device, 102... Reactor water level signal, 10
4... Water supply flow rate signal, 106... Main steam flow rate signal, 107...
Water supply flow rate request signal, 108...Selection control rod insertion request signal,
205...T/D-RFP 1 unit selection trip signal, 206
...M/D-RFP activation prevention signal, 207, 210, 21
3...Setter, 208, 211, 212...Comparator, 209
, 214...timer, 215...trip signal, 216...
M/D-RFP 2 unit activation signal, 217...signal.

Claims (7)

[Claims] 1. A steam generator, a turbine for introducing steam generated by the steam generator through a main steam pipe, a generator connected to the turbine, and a steam control valve provided in the main steam pipe. A steam generator comprising: a condenser that condenses the steam discharged from the turbine; a water supply pipe that guides the water condensed in the condenser to the steam generator; and a water supply pump installed in the water supply pipe. 1. A water feed pump control device for a plant, characterized in that the feed water pump control device is provided with a control means for tripping the feed water pump when a selected control rod is inserted. 2. In the feed water pump control device for a steam generation plant according to claim 1, at least one of the feed water flow rate, the feed water pump flow rate, or the feed water flow rate request signal calculated by the feed water flow rate control device is set to a predetermined value. A water supply pump control device characterized by comprising a control means for tripping the water supply pump when the following conditions occur. 3. The control device according to claim 1 or 2, wherein a turbine-driven water pump (hereinafter referred to as T/D-RFP) 2
stand and motor-driven water pump (hereinafter referred to as M/D-RF
(referred to as P), the selection control rod is inserted, and the T/D
- When the water supply flow rate remains below setting 1, which is a value determined based on the lower limit flow rate that can be narrowed down by two REP units (minimum flow valve closed state), for a predetermined period of time, the T/
At the same time as stopping one D-RFP, M/D-RFP
The water supply flow rate remained below setting 2, which is a value determined based on the lower limit flow rate that can be narrowed down by one T/D-RFP (minimum flow valve closed state), for a predetermined period of time. Sometimes, a control means is provided to start the M/D-RFP at the same time as the remaining one T/D-RFP is stopped, or to suddenly open the minimum flow valve of the T/D-RFP in operation. Characteristic water pump control device. 4. The control device according to claim 1 or 2, wherein M/
In the case of a plant with three D-RFPs, a selection control rod is inserted to ensure that the water supply flow rate falls below setting 1, which is a value determined based on the lower limit flow rate that can be narrowed down by two M/D-RFPs (minimum flow valve closed state). When the rotating state continues for a predetermined period of time, one M/D-RFP is stopped and at the same time,
Preventing automatic activation of the spare M/D-RFP and further M/D-RFP
When the water supply flow rate remains below setting 2, which is a value determined based on the lower limit flow rate that can be narrowed down by one D-RFP (minimum flow valve closed state), for a predetermined period of time, the minimum flow valve is suddenly opened. A water supply pump control device characterized by: 5. The water supply pump control device according to claim 3, wherein a water supply flow rate request signal calculated by the water supply flow rate control device is used instead of the water supply flow rate. 6. The water supply pump control device according to claim 3, wherein the pump flow rate is used instead of the water supply flow rate. 7. The water supply pump control device according to claim 3, wherein the water supply pump is characterized in that an interlock is activated when the reactor water level is higher than a predetermined value as a permission condition. Control device.