JP2011180013A - System and method for operating feed water system in nuclear power plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a feed water operation system which attains a stable and continuous plant operation, even when there is a trip of a low-pressure condensate pump 2 during a thermal output improved operation. <P>SOLUTION: When a normal operation function 22 of stand-by machines of condensate pumps is actuated, three pumps of low-pressure condensate pumps 2 to 4 and high-pressure condensate pumps 8 to 10 go into operation. The suction pressure of feed water pumps 12 and 13 for driving turbines in a normal operation rises in comparison with the time when the normal operation function 22 of the stand-by machines of the condensate pumps is not actuated ( state with two pumps working). Even in case of a trip of the low-pressure condensate pump 2, moreover, the degree of the degradation in the suction pressure of the feed water pumps 12 and 13 for driving the turbines is lower than that when the normal operation function 22 of the stand-by machines of the condensate pumps does not actuate. The suction pressure of the feed water pump 13 for driving the turbines is never lower than the trip set point, and there is no risk that the pump 13 for driving the turbines is in a danger for automatic stop. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water supply operation system of a nuclear power plant, and more particularly to a water supply operation system in a heat output improvement operation of an existing nuclear power plant.

  The water supply operation system of a nuclear power plant is configured to supply condensate condensed by a condenser to a nuclear reactor via a condensate pump and a water supply pump. In general, the condensate pump is composed of a low-pressure condensate pump (a group of two regular pumps and one spare pump) and a high-pressure condensate pump (a group of two regular pumps and one spare pump). The high pressure condensate pump is installed downstream of the low pressure condensate pump. Each low-pressure condensate pump has a capacity of 50%. Each high-pressure condensate pump has a capacity of 50%. The feed water pump is composed of two turbine-driven feed water pumps and two motor-driven feed water pumps which are spare machines. Turbine-driven water pumps have a capacity of 50% per unit, and motor-driven water pumps have a capacity of 25% per unit.

  In such a water supply operation system, a trouble occurs during operation of two low-pressure condensate pumps, two high-pressure condensate pumps, and two turbine-driven feed water pumps, and one of the condensate pumps (for example, a low-pressure condensate pump). Trips and one of the other condensate pumps continues to operate, there is an imbalance in the number of units operating between the upstream and downstream pumps. As a result, the suction pressure of the water supply pump installed downstream is descend. When the suction pressure of the feed water pump decreases, the effective suction head of the pump decreases and cavitation may occur. Cavitation can cause pump failure.

  In order to prevent the occurrence of such cavitation, the water supply operation system of a nuclear power plant is provided with an interlock function (for example, Patent Document 1). The interlock function detects an imbalance of the number of operating pumps, such as the number of upstream pumps operating less than the number of downstream pumps, automatically stops the downstream pumps, and then starts each pump spare unit sequentially from the upstream side. Let For example, when one of the low-pressure condensate pumps trips and the other low-pressure condensate pump continues to operate, the number of low-pressure condensate pumps operated is one high-pressure condensate pump, turbine-driven feed water pump. Since there will be two operating units each, and there will be an imbalance in the number of units in operation, one high-pressure condensate pump and one turbine-driven feed water pump are automatically stopped, and after starting the low-pressure condensate pump spare machine, Control is performed such that the high-pressure condensate pump spare machine is activated and two motor-driven feed water pumps are activated. The interlock function means that when one of the high-pressure condensate pumps trips, the number of operating high-pressure condensate pumps is one, whereas the number of turbine-driven feed pumps that operate is two, and the number of operating units is unbalanced. Therefore, after one turbine-driven feed water pump is automatically stopped and a high-pressure condensate pump spare machine is started, control is performed such that two motor-driven feed water pumps are sequentially started.

  During such an interlock function operation, the suction pressure of one turbine-driven feed water pump that continues to operate is transiently reduced. That is, if one of the two low-pressure condensate pumps is tripped for some reason, one high-pressure condensate pump on the downstream side and one turbine-driven feed water pump when the interlock function is activated. Automatically stops. The flow through the low-pressure condensate pumps that have been transiently operated by one unit is increased by the decrease in the number of operating units until each spare unit is started up sequentially, so the head of the low-pressure condensate pump that continues to operate decreases. As a result, the suction pressure of the high-pressure condensate pump decreases. Furthermore, since the flow rate flowing through the high-pressure condensate pump that has been transiently operated by one unit increases due to a decrease in the number of operating units, the head of the high-pressure condensate pump that continues to operate decreases, and as a result, the suction pressure of the feed water pump decreases. descend.

  On the other hand, when the suction pressure falls below a predetermined trip set value, the turbine-driven feed water pump automatically stops to protect the pump. At the time of rated output operation, which will be described later, the nuclear power plant water supply operation system is designed at the plant design stage so that even if the suction pressure of the turbine-driven water supply pump drops when the interlock function is activated, it does not fall below the specified trip set value. Specifications are set. Thereby, even if one of the low-pressure condensate pumps trips and the interlock function is activated, the plant operation can be stably continued without lowering the reactor heat output.

  By the way, an attempt is made to effectively utilize an existing nuclear power plant, and an operation of improving the heat output of a nuclear reactor has been studied by remodeling the existing nuclear power plant (for example, Non-Patent Document 1). In the existing nuclear power plant, the specifications of each facility were set on the assumption of rated output (100% output) operation. In such an existing nuclear power plant, if it is attempted to improve the heat output (for example, 110% of the rated output), the water supply system needs to increase the water supply flow rate in conjunction with the increase in output.

Japanese Patent Publication No. 63-271005

Ministry of Economy, Trade and Industry Comprehensive Resource and Energy Study Group Nuclear Safety and Security Agency Nuclear Safety Safety Subcommittee Reactor Thermal Power Improvement Working Group 1st Handout 1-1

  In general, a pump has a pump characteristic that a head, which is a difference in pressure between the inlet and outlet of the pump, decreases as the feed water flow rate increases.

  When the feed water flow rate increases during the heat output improvement operation, the head of the low pressure condensate pump is lowered according to the pump characteristics, and the suction pressure of the high pressure condensate pump installed downstream of the low pressure condensate pump is lowered. In addition, the head of the high-pressure condensate pump decreases according to the pump characteristics. As a result, the suction pressure of the water supply pump installed further downstream is reduced as compared with that before the heat output is improved (during rated output operation).

  As described above, when one of the low-pressure condensate pumps trips and the interlock function is activated, the suction pressure of one turbine-driven feed water pump that continues to operate decreases transiently.

  During rated output (100% output) operation, the specifications are set so that even if the suction pressure of the turbine-driven feed water pump decreases during the interlock function operation, it does not fall below a predetermined set value. The turbine-driven feed water pump that continues to operate does not automatically stop.

  However, during the heat output improvement operation, the suction pressure of the water supply pump before the interlock function is activated is lower than that during the rated output operation, so the interlock function is activated and the turbine-driven water supply pump continues to operate. When the suction pressure of one unit further decreases, the turbine-driven feed water pump that continues to operate below a predetermined set value may automatically stop.

  When the two turbine-driven feed water pumps are stopped, there is a possibility that so-called total feed water loss will occur. The total water loss event itself is evaluated as an accident event in the safety analysis and measures are taken for the safety of the reactor, but it will affect the plant availability.

  As countermeasures for such problems, replacement of the condensate pump with a high head type and additional installation of a condensate pump are conceivable. However, contrary to the purpose of effectively using the existing nuclear power plant, from the viewpoint of the plant economy. It is not preferable.

  The objective of this invention is providing the water supply operation system of the nuclear power plant which can continue a plant operation stably, even when one condensate pump trips during the heat output improvement operation of the existing nuclear power plant.

  (1) In order to achieve the above object, the present invention includes a condenser that condenses steam, and condensate condensed in the condenser, and includes a plurality of regular machines and spare machines, Condensate pumps arranged in parallel, and installed downstream of the condensate pump, further boosting the discharge water of the condensate pump and feeding it to the reactor, including a plurality of regular machines and spare machines, A water supply pump arranged in parallel, and a control means for controlling the condensate pump and the water feed pump are provided, and the control means is configured to control the condensate pump when one of the condensate pump regular machines trips. And detecting an imbalance in the number of operating water pumps, automatically stopping one of the water pump regular machines, automatically starting the condensate pump spare machine, and then automatically starting the water pump spare machine. Water supply operation of nuclear power plant with lock function In the stem, wherein, during the heat output increase operation, having a condensate pump spare machine continuously operating function to operate the condensate pump spare machine at all times.

  In the present invention configured as described above, when the condensate pump preliminary machine continuous operation function is activated, all the condensate pumps are in an operating state, the discharge flow rate of each pump is reduced, and the head of each pump is adjusted according to the pump characteristics. To rise. As a result, the suction pressure of the water supply pump at the normal time increases compared to when the condensate pump spare machine always-on function is not activated. Furthermore, even if the condensate pump trips in this state, the suction pressure drop of the feed water pump is less than that when the condensate pump preliminary machine continuous operation function is not activated. The suction pressure of the feed water pump does not fall below the trip set value, and there is no possibility that the feed water pump automatically stops. Thereby, even when one condensate pump trips during the heat output improvement operation of the existing nuclear power plant, the plant operation can be stably continued.

  (2) In the above (1), preferably, the plurality of condensate pumps include a plurality of regular units and a spare unit, which are arranged in parallel, and downstream of the low pressure condensate pump. A high-pressure condensate pump that is installed on the side and includes a plurality of regular machines and spare machines, and the interlock function of the control means is one of the low-pressure condensate pump regular machines. When a trip occurs, one of the high-pressure condensate pumps is automatically stopped by detecting an imbalance in the number of operating low-pressure condensate pumps, the high-pressure condensate pumps, and the feed water pumps, One of the machines is automatically stopped and the low-pressure condensate pump spare machine is automatically activated, then the high-pressure condensate pump spare machine is automatically activated, the feed water pump spare machine is automatically activated, and the control means is restored. Water pump spare machine always Operation function, at the time of the heat output increase operation, thereby continuously operating at least the low-pressure condensate pump spare machine.

  Generally, the condensate pump is composed of a low-pressure condensate pump and a high-pressure condensate pump installed downstream thereof. Comparing the case where one low-pressure condensate pump trips and the case where one high-pressure condensate pump trips, the suction of the feed pump located downstream is more when the low-pressure condensate pump trips on the most upstream side. Large impact on pressure.

  By always operating at least the low-pressure condensate pump spare machine, plant operation can be stably continued even when one low-pressure condensate pump trips during the heat output improvement operation of the existing nuclear power plant.

  (3) In order to achieve the above object, the present invention includes a condenser that condenses steam, and condensate condensed in the condenser, and includes a plurality of regular machines and spare machines. Condensation pumps arranged in parallel, and a plurality of regular machines and spare machines installed downstream of the condensate pumps, further boosting the discharge water of the condensate pumps and feeding them to the reactor, An operation method of a water supply system of a nuclear power plant provided with a water supply pump arranged in parallel, and when one of the condensate pump regular machines trips during rated output operation, the interlock of the water supply system In the operation method of the nuclear power plant water supply system in which the function is activated, one of the water pump regular machines is automatically stopped, the condensate pump spare machine is automatically started, and then the water pump spare machine is automatically started. During operation to improve heat output There are, thereby driving the condensate pump spare machine at all times.

  According to the water supply operation system of the present invention, plant operation can be stably continued even when one condensate pump trips during the heat output improvement operation of the existing nuclear power plant.

It is a schematic block diagram of the water supply operation system of a nuclear power plant. It is a figure which shows the general characteristic of a pump. It is a flowchart which shows a process of an interlock function. (A) It is a figure explaining the outline | summary of the normal pressure state in a water supply operation system. (B) It is a figure explaining the outline | summary of the pressure state at the time of the low pressure condensate pump trip in a water supply operation system. (At rated output operation) (A) It is a figure which shows the flow volume behavior of the feed water pump at the time of a low-pressure condensate pump trip. (B) It is a figure which shows the behavior of the suction pressure of the turbine drive feed water pump at the time of a low-pressure condensate pump trip. (During rated output operation) (A) It is a figure explaining the outline | summary of the normal pressure state in a water supply operation system. (B) It is a figure explaining the outline | summary of the pressure state at the time of the low pressure condensate pump trip in a water supply operation system. (During heat output operation / condensate pump spare machine continuous operation function not activated) (A) It is a figure which shows the flow volume behavior of the feed water pump at the time of a low-pressure condensate pump trip. (B) It is a figure which shows the behavior of the suction pressure of the turbine drive feed water pump at the time of a low-pressure condensate pump trip. (During heat output operation / condensate pump spare machine continuous operation function not activated) (A) It is a figure explaining the outline | summary of the normal pressure state in a water supply operation system. (B) It is a figure explaining the outline | summary of the pressure state at the time of the low pressure condensate pump trip in a water supply operation system. (During heat output improvement operation / Condensate pump spare machine continuous operation function operation) (A) It is a figure which shows the flow volume behavior of the feed water pump at the time of a low-pressure condensate pump trip. (B) It is a figure which shows the behavior of the suction pressure of the turbine drive feed water pump at the time of a low-pressure condensate pump trip. (During heat output improvement operation / Condensate pump spare machine continuous operation function operation) It is a figure which shows the relationship between a feed water flow rate and the head of a turbine drive feed water pump.

<First Embodiment>
~Constitution~
The water supply operation system of this invention is demonstrated in detail using drawing.

  FIG. 1 is a schematic configuration diagram of a water supply operation system of a nuclear power plant. In the nuclear power plant, the turbine 31 is rotated by the steam generated from the nuclear reactor 19 and electric power is generated by the generator 32 directly connected to the turbine. The water supply operation system supplies water to the nuclear reactor 19. From the upstream side, the condenser 1, the low pressure condensate pumps 2 to 4, the air extractor condenser 5, the ground steam condenser 6, the condenser A water filtration / desalination device 7, a high pressure condensate pump 8 to 10, a low pressure feed water heater 11, a feed water pump 12 to 15, a high pressure feed water heater 18, a nuclear reactor 19, and a control device 20 are provided. ing.

  An outline of the pressure state in the water supply operation system will be described (see FIG. 4A described later). The condenser 1 cools and condenses the water vapor after taking out work by the turbine 31, and returns it to a low-pressure saturated liquid (condensate). The low pressure condensate pumps 2 to 3 increase the pressure of the condensate condensed in the condenser 1. Pressure loss occurs when passing through the air extractor condenser 5, the ground steam condenser 6, and the condensate filtration / desalination device 7. The high pressure condensate pumps 8 and 9 increase the pressure of the condensate via the air extractor condenser 5, the ground steam condenser 6, and the condensate filtration / desalination device 7. The low-pressure feed water heater 11 heats the condensate, but pressure loss occurs when the water is passed. The feed pumps 12 and 13 further boost the condensate. The high-pressure feed water heater 18 heats the condensate, but pressure loss occurs when water is passed. The heated condensate is sent to the nuclear reactor 19. Thereby, a predetermined reactor pressure is obtained.

  Here, the condensate pressure on the suction side of the pump is defined as the suction pressure, the condensate pressure on the discharge side of the pump is defined as the discharge pressure, and the difference between the discharge pressure and the suction pressure is defined as the pump head. In other words, the discharge pressure is a pressure that is equivalent to the pump head with respect to the suction pressure.

  The low pressure condensate pumps 2 to 4 are installed in parallel. During rated output (100% output) operation, the low-pressure condensate pumps 2 and 3 are always operated, and the low-pressure condensate pump 4 is a spare machine. During the heat output improvement (for example, 110%) operation, the low pressure condensate pumps 2 to 4 are always operated.

  The high-pressure condensate pumps 8 to 10 are installed in parallel. During the rated output operation, the high-pressure condensate pumps 8 and 9 are always operated, and the high-pressure condensate pump 10 is a spare machine. During the heat output improvement operation, the high-pressure condensate pumps 8 to 10 are always operated.

  The feed water pump is composed of turbine-driven feed water pumps 12 and 13 and electric motor-driven feed water pumps 14 and 15. The turbine-driven feed water pumps 12 and 13 and the motor-driven feed water pumps 14 and 15 are installed in parallel. In both the rated output operation and the heat output improvement operation, the turbine-driven feed water pumps 12 and 13 are always operated, and the motor-driven feed water pumps 14 and 15 are used as spare machines. When the electric motor driven feed water pumps 14 and 15 are used, the flow rate is controlled by the feed water control valves 16 and 17 installed on the discharge side.

  FIG. 2 is a diagram showing general pump characteristics such as the low pressure condensate pumps 2 to 4, the high pressure condensate pumps 8 to 10, and the feed water pumps 12 to 15. As the pump flow rate increases, the pump head tends to decrease.

  The control device 20 controls the low pressure condensate pumps 2 to 4, the high pressure condensate pumps 8 to 10, and the feed water pumps 12 to 15. The control device 20 has an interlock function 21. FIG. 3 is a flowchart showing the processing of the interlock function 21. When the low-pressure condensate pump 2 is tripped and the other low-pressure condensate pump 3 is continuously operated, the interlock function 21 is operated when the low-pressure condensate pump 3 and the high-pressure condensate pumps 8 and 9 and the feed water pumps 12 and 13 are operated. (S1), the high-pressure condensate pump 8 and the turbine-driven feed water pump 12 are automatically stopped (S2-3), and the low-pressure condensate pump spare machine 4 is started. After that (S4), the high pressure condensate pump preliminary machine 10 is sequentially activated (S5), and the motor driven feed water pumps 14 and 15 are activated (S6).

  When the high pressure condensate pump 8 trips and the other high pressure condensate pump 9 continues to operate, the interlock function 21 determines that there is an imbalance in the number of operating units between upstream and downstream, and the turbine drive After the feed water pump 12 is automatically stopped and the high-pressure condensate pump preliminary machine 10 is activated, control is performed such that the motor-driven feed water pumps 14 and 15 are activated. Further, the interlock function 21 performs control such that the motor-driven feed water pumps 14 and 15 are activated when the turbine-driven feed water pump 12 trips and the other turbine-driven feed water pump 13 continues to operate. However, when the low-pressure condensate pump 2 on the most upstream side trips, the influence on the suction pressure of the feed water pump on the downstream side is great, so in this embodiment, the low-pressure condensate pump 2 mainly trips. Describe the case.

  The control device 20 has a condensate pump preliminary machine continuous operation function 22 as a characteristic configuration. The condensate pump spare machine continuous operation function 22 controls the low-pressure condensate pump 4 and the high-pressure condensate pump 10 that were spare machines during the rated output operation so that they are always operated during the heat output improvement operation.

~ Operation ~
(Operation 1) The operation of the water supply operation system during rated output (100% output) operation will be described.

  First, the operation at the normal time (before the low pressure condensate pump trip) will be described. FIG. 4A is a diagram illustrating an outline of a normal pressure state in the water supply operation system.

  The steam generated from the nuclear reactor 19 rotates the turbine 31, and the steam after work is cooled and condensed by the condenser 1 to become condensed water. The condensate condensed in the condenser 1 is increased in pressure by low-pressure condensate pumps 2 and 3 which are regular machines, and passes through heat exchangers such as an air extractor condenser 5 and a ground steam condenser 6, The water passes through the water filtration / desalination device 7 and is fed to the high-pressure condensate pumps 8 and 9 which are regular machines. The condensate whose pressure has been increased by the high-pressure condensate pumps 8 and 9 is heated by the low-pressure feed water heater 11, further boosted by the turbine-driven feed water pumps 12 and 13 which are regular machines, and then heated by the high-pressure feed water heater 18. Then, water is sent to the nuclear reactor 19. The low-pressure condensate pump 4, the high-pressure condensate pump 10, and the motor-driven feed water pumps 14 and 15, which are spare machines, are in a standby state.

  Next, the operation of the water supply operation system when the interlock function 21 is activated will be described. FIG. 4B is a diagram illustrating an outline of a pressure state when a low-pressure condensate pump trips (when the interlock function 21 is activated) in the water supply operation system.

  In order to protect the downstream pump from the cause of failure due to the upstream pump trip, the interlock function 21 is activated during the pump trip. In addition, since the case where the low pressure condensate pump 2 on the most upstream side is tripped has a large influence on the suction pressure of the water supply pump on the downstream side, in this embodiment, the case where the low pressure condensate pump 2 is tripped mainly. Is described. The low pressure condensate pump 2 trips and the other low pressure condensate pump 3 continues to operate. In sequence, the high-pressure condensate pump 8 and the turbine-driven feed water pump 12 automatically stop. The high-pressure condensate pump 9 and the turbine-driven feed water pump 13 continue to operate. After the low-pressure condensate pump preliminary machine 4 is started, the high-pressure condensate pump preliminary machine 10 is sequentially started, and the motor-driven feed water pumps 14 and 15 are further started.

  During such an interlock function operation, the suction pressure of the turbine-driven feed water pump 13 that continues to operate is transiently reduced. In order to confirm this, the inventor conducted a dynamic characteristic analysis. The analysis results are shown in FIG.

  FIG. 5A is a diagram showing the flow behavior of the feed water pumps 12 to 15 when the low pressure condensate pump 2 trips. The thick line in the figure indicates the total flow rate of the feed water pumps 12 to 15 (the feed water flow rate to the nuclear reactor 19), the broken line indicates the discharge flow rate of the turbine-driven feed water pump 12 that automatically stops, and the middle line indicates the turbine-driven feed water pump that continues operation. 13 shows the discharge flow rate, and the thin line shows the discharge flow rate of each of the motor-driven feed water pumps 14 and 15.

  When the turbine drive feed pump 12 automatically stops, the discharge flow rate of the turbine drive feed pump 12 decreases rapidly. The motor-driven water supply pumps 14 and 15 are started with a time delay, and the discharge flow rate of the motor-driven water supply pumps 14 and 15 increases rapidly, and when it reaches a predetermined amount, the balance is maintained. The turbine-driven feed water pump 13 continues to operate alone until the turbine-driven feed water pump 12 automatically stops and the motor-driven feed water pumps 14 and 15 are activated, and the discharge flow rate of the turbine-driven feed water pump 13 increases. When the motor-driven feed water pumps 14 and 15 are activated, the discharge flow rate of the turbine-driven feed water pump 13 once decreases, but after a while, the equilibrium is maintained.

  Normally, the feed water flow rate is constant. While the turbine-driven feed water pump 13 continues to operate with one unit, the feed water flow rate is reduced compared to the normal time. When the motor-driven feed water pumps 14 and 15 are started, the feed water flow rate increases. The water level of the nuclear reactor 19 is controlled so as to be kept constant. Therefore, in order to recover the water level that has decreased due to the decrease in the feed water flow rate, the feed water flow rate after the motor-driven feed pumps 14 and 15 are started increases compared to the normal time.

  FIG. 5B is a diagram showing the behavior of the suction pressure of the turbine-driven feed water pump 13 when the low-pressure condensate pump 2 trips. When the low-pressure condensate pump 2 trips and the low-pressure condensate pump 3 continues to operate, the discharge flow rate of the low-pressure condensate pump 3 that is transiently in operation is increased. The head of the water pump 3 is lowered. As a result, the suction pressure of the high pressure condensate pump 9 decreases. In addition, when the high pressure condensate pump 8 is automatically stopped and the high pressure condensate pump 9 continues to operate, the discharge flow rate of the high pressure condensate pump 9 that is transiently in operation is increased. The head of the high-pressure condensate pump 9 is lowered. As a result of the suction pressure of the high-pressure condensate pump 9 being lowered and the lift of the high-pressure condensate pump 9 being further lowered, the suction pressure of the turbine-driven feed water pump 13 that is continuing to operate is transiently lowered (see FIG. 4B). .

  By the way, the turbine drive feed pump 13 is set to automatically stop for pump protection when the suction pressure falls below a predetermined trip set value. The trip set value is shown in the figure.

  In the figure, the state A shows a state where the suction pressure of the turbine-driven feed water pump 13 is transiently lowered due to the trip of the low-pressure condensate pump 2. In the state A, the turbine-driven feed water pump 13 does not automatically stop because its suction pressure is not lower than the trip set value. In other words, the specifications are set at the plant design stage so that even if the suction pressure of the turbine-driven feed water pump 13 is reduced during operation of the interlock function during rated output operation, the trip set value is not reduced. Thereby, even when the low pressure condensate pump 12 trips and the interlock function 21 is activated, the plant operation can be stably continued without lowering the reactor heat output.

  After that, when the low-pressure condensate pump preliminary machine 4 is started, two units of the low-pressure condensate pump 3 are operated, and the discharge flow rate per pump decreases, so that the head of the low-pressure condensate pump 2 increases according to the pump characteristics. To do. As a result, the suction pressure of the high-pressure condensate pump 9 increases. Furthermore, when the high-pressure condensate pump spare machine 10 is started, two high-pressure condensate pumps 9 are in operation, and the discharge flow rate per pump decreases, so the head of the high-pressure condensate pump 9 increases according to the pump characteristics. To do. As a result of the suction pressure of the high-pressure condensate pump 9 increasing and the lift of the high-pressure condensate pump 9 increasing, the suction pressure of the turbine-driven feed water pump 13 that continues to operate increases transiently.

  When the low-pressure condensate pump spare machine 4, the high-pressure condensate pump spare machine 10, and the motor-driven feed water pumps 14 and 15 are activated, the water level of the reactor 19 that has dropped due to the reduction of the feed water flow rate is recovered. To increase. When the discharge flow rate of the low-pressure condensate pumps 3 and 4 increases, the head of the low-pressure condensate pumps 3 and 4 decreases according to the pump characteristics, and the suction pressure of the high-pressure condensate pumps 9 and 10 decreases. When the discharge flow rate of the high-pressure condensate pumps 9 and 10 increases, the head of the high-pressure condensate pumps 9 and 10 decreases according to the pump characteristics. The suction pressure of the high-pressure condensate pumps 9 and 10 is lowered, and the lift of the high-pressure condensate pumps 9 and 10 is lowered. As a result, the suction pressure of the turbine-driven feed water pump 13 is gradually lowered and lowered compared to the normal time. To maintain equilibrium.

  In the figure, state B shows a state in which equilibrium is maintained in a state where the suction pressure of the turbine-driven feed water pump 13 is lower than that in the normal state. In the state B, the turbine-driven feed water pump 13 does not automatically stop because its suction pressure is not lower than the trip set value. Conversely, at the time of rated output operation, there are various factors at the plant design stage so that even if the suction pressure of the turbine-driven feed water pump 13 drops when the reactor 19 water level recovers after the interlock function is activated, it does not fall below the trip set value. The origin is set. Thereby, even when the water level of the reactor 19 is recovered after the interlock function 21 is activated, the plant operation can be stably continued without lowering the reactor heat output.

  (Operation 2) The operation of the water supply operation system during the heat output improvement operation when the condensate pump preliminary machine continuous operation function 22 which is a characteristic configuration of the present embodiment does not operate will be described.

  FIG. 6A is a diagram illustrating an outline of a normal pressure state in the water supply operation system. When the condensate pump preliminary machine continuous operation function 22 does not operate, that is, when the low-pressure condensate pump 4 and the high-pressure condensate pump 10 are in a standby state as spare units, the normal operation of the water supply operation system is the rated output operation. It is the same as the operation of the normal water supply operation system. However, during the heat output improvement operation, the feed water flow rate increases in comparison with the rated output operation in conjunction with the output increase (see FIG. 7A). Accordingly, the discharge flow rate of each pump 2, 3, 8, 9 increases, and the head of each pump 2, 3, 8, 9 decreases according to the pump characteristics. As a result, even during normal times, the suction pressure of the turbine-driven feed water pumps 12 and 13 is lower than before the heat output is improved (during rated output operation) (see FIG. 7B).

  FIG. 6B is a diagram illustrating an outline of the pressure state when the low-pressure condensate pump trips (when the interlock function 21 is activated) in the water supply operation system. When the low-pressure condensate pump trips, the suction pressure of the turbine-driven feed water pump 13 that continues to operate is lower than that in the normal state, similar to the content described in FIG. 4B.

  The inventor performed dynamic characteristic analysis on the assumption that the low pressure condensate pump 2 on the most upstream side tripped and the interlock function 21 was activated during the heat output improvement (for example, 110% output) operation. The analysis results are shown in FIG.

  FIG. 7A is a diagram showing the flow behavior of the feed water pumps 12 to 15 when the low pressure condensate pump 2 trips. The contents shown are the same as in FIG. 5A. For comparison, the normal water supply flow rate during rated output operation is added. A flow rate behavior similar to the flow rate behavior at the rated output operation (FIG. 5A) is shown, but the flow rate fluctuation becomes large as a whole.

  FIG. 7B is a diagram showing the behavior of the suction pressure of the turbine-driven feed water pump 13 when the low-pressure condensate pump 2 trips. The contents shown are the same as in FIG. 5B. For comparison, the suction pressure of the turbine-driven feed water pump 13 at the normal time during the rated output operation is added. It shows a pressure behavior similar to the pressure behavior during rated power operation (FIG. 5A). Details of the behavior are the same as those described in FIG. However, the suction pressure as a whole is lower than the pressure behavior during rated output operation.

  In the state A, the suction pressure of the turbine-driven feed water pump 13 is lower than the trip set value. Therefore, there is a possibility that the turbine-driven feed water pump 13 is automatically stopped.

  Further, even if the turbine-driven water supply pump 13 does not automatically stop in the state A, the turbine-driven water supply pump 13 in the state B may be automatically stopped because its suction pressure falls below the trip set value.

  When the two turbine-driven feed water pumps 12 and 13 are stopped, the water supply to the nuclear reactor is stopped, and there is a possibility that the entire water supply is lost.

  The above operation is based on the dynamic characteristic analysis result assuming various conditions, and does not actually cause the problem of the state A or the state B in FIG. 7B.

  (Operation 3) The operation of the water supply operation system during the heat output improvement operation when the condensate pump preliminary machine continuous operation function 22 which is a characteristic configuration of the present embodiment operates will be described.

  FIG. 8A is a diagram illustrating an outline of a normal pressure state in the water supply operation system. When the condensate pump preliminary machine continuous operation function 22 is activated, the low-pressure condensate pump 4 and the high-pressure condensate pump 10 which are the spare machines are in a normal operation state as regular machines. As a result, the three low-pressure condensate pumps 2 to 4, the three high-pressure condensate pumps 8 to 10, and the two turbine-driven feed water pumps 12 and 13 are always in operation. The motor driven feed water pumps 14 and 15 remain in a standby state.

  During the heat output improvement operation, the feed water flow rate increases in comparison with the rated output operation in conjunction with the output increase (see FIG. 9A). On the other hand, each of the two low-pressure condensate pumps 2 to 4 and the high-pressure condensate pumps 8 to 10 are operated in three units, compared to the two-unit operation state (the condensate pump preliminary machine continuous operation function 22 is not activated). The discharge flow rate of 4, 8 to 10 decreases, and the head of each pump increases according to the pump characteristics. As a result, even during normal times, the suction pressure of the turbine-driven feed water pumps 12 and 13 increases compared to the two-unit operation state (see FIG. 9B).

  When the low-pressure condensate pump 2 trips and the low-pressure condensate pumps 3 and 4 continue to operate, two units are in operation. The number of operating high-pressure condensate pumps is 3 with respect to the number of operating low-pressure condensate pumps, and the number of operating units is unbalanced. Therefore, the interlock function 21 automatically stops the high-pressure condensate pump 8. On the other hand, the number of operating turbine-driven feed pumps is two, and there is no imbalance with the number of operating upstream pumps, so the turbine-driven feed pumps 12, 13 do not stop automatically.

  FIG. 8B is a diagram illustrating an outline of a pressure state when a low-pressure condensate pump trips in the water supply operation system.

  The inventor assumes that the low pressure condensate pump 2 on the most upstream side has tripped in the state in which the condensate pump preliminary machine continuous operation function 22 is activated during the heat output improvement (for example, 110% output) operation, and the dynamic characteristics. Analysis was performed. The analysis results are shown in FIG.

  FIG. 9A is a diagram showing the flow behavior of the feed water pumps 12 to 15 when the low pressure condensate pump 2 trips. The contents shown are the same as in FIG. 5A. For comparison, the normal water supply flow rate during rated output operation is added.

  The upstream low-pressure condensate pump 2 trip and the high-pressure condensate pump 8 are automatically stopped, so that the feed water flow rate is temporarily reduced slightly, and the discharge flow rates of the turbine-driven feed water pumps 12 and 13 on the downstream side are also temporarily slightly reduced. To decrease. If the operation state of the two low-pressure condensate pumps 2 and 3 and the high-pressure condensate pumps 9 and 10 is stabilized, the discharge flow rates of the turbine-driven feed water pumps 12 and 13 also return to normal times. During the series of operations, the feed water flow rate is not significantly reduced, and the water level of the reactor 19 is not significantly lowered. As described above, the flow behavior when the condensate pump preliminary machine continuous operation function 22 is activated is more stable than the flow behavior when the condensate pump preliminary machine continuous operation function 22 is not activated (see FIG. 7A).

  FIG. 9B is a diagram showing the behavior of the suction pressure of the turbine-driven feed water pump 13 when the low-pressure condensate pump 2 trips. The contents shown are the same as in FIG. 5B. For comparison, the suction pressure of the turbine-driven feed water pump 13 at the normal time when the condensate pump preliminary machine continuous operation function 22 is not operated (two-unit operation state) is additionally shown. The turbine-driven feed water pump 12 also continues to operate and exhibits the same pressure behavior as the suction pressure behavior of the turbine-driven feed water pump 13, but is not shown.

  When the low-pressure condensate pump 2 trips and the low-pressure condensate pumps 3 and 4 continue to operate, the discharge flow rate of each of the low-pressure condensate pumps 3 and 4 in the two-unit operation state increases. The lift of the low-pressure condensate pumps 3 and 4 is lowered. As a result, the suction pressure of the high-pressure condensate pumps 8 to 10 on the downstream side decreases. Further, when the high pressure condensate pump 8 is automatically stopped and the high pressure condensate pumps 9 and 10 continue to operate, the discharge flow rates of the high pressure condensate pumps 9 and 10 that are in the two-unit operation state increase. According to the pump characteristics, the heads of the high-pressure condensate pumps 9 and 10 are lowered. As a result, the suction pressure of the turbine-driven feed water pumps 12 and 13 decreases. However, comparing the case where two condensate pumps are one (operation 2) and the case where two condensate pumps are two (operation 3), the discharge flow increases in the case of operation 3. Is less. Accordingly, the degree of pressure drop is small compared to when the condensate pump preliminary machine continuous operation function 22 is not activated (see FIG. 8B).

  In addition, since the suction pressure of the turbine-driven feed water pumps 12 and 13 is higher than that in the operation state of two units at normal times (see FIG. 8A), the turbine-driven feed water is automatically stopped by tripping the low-pressure condensate pump 2 and the high-pressure condensate pump 8 automatically. Even if the suction pressure of the pumps 12 and 13 is slightly reduced, the trip set value is not lowered, and there is no possibility that the turbine-driven feed water pumps 12 and 13 are automatically stopped. That is, the problem like the state A of FIG. 7B does not arise.

  Since the flow behavior after two low-pressure condensate pumps and two high-pressure condensate pumps are stable, the pressure behavior is also stable, and the turbine-driven feed water pumps 12 and 13 have their suction pressure set to trip. There is no possibility that the turbine-driven feed water pumps 12 and 13 are automatically stopped. That is, the problem like the state B of FIG. 7B does not arise.

  (Operation 4) In operations 2-3, the operation of the water supply operation system when the low pressure condensate pump 2 trips during the heat output improvement operation has been described. However, the water supply operation when the high pressure condensate pump 8 trips during the heat output improvement operation The operation of the system will be described.

  If the condensate pump preliminary machine continuous operation function 22 is not activated, the two high-pressure condensate pumps 8 and 9 are in an operating state. When the high-pressure condensate pump 8 trips in this state, one high-pressure condensate pump 9 continues to operate, and the interlock function 21 is activated. The turbine-driven feed water pump 12 automatically stops, and after the high-pressure condensate pump preliminary machine 10 is activated, the motor-driven feed water pumps 14 and 15 are sequentially activated.

  When such an interlock function is activated, the discharge flow rate of the high-pressure condensate pump 9 that is transiently in operation is increased, so that the head of the high-pressure condensate pump 9 is lowered according to the pump characteristics. As a result, the suction pressure of the turbine-driven feed water pump 13 that continues to operate decreases transiently.

  The cause of the decrease in the suction pressure of the turbine-driven feed water pump 13 is only a decrease in the lift of the high-pressure condensate pump 9, and the degree of the pressure decrease is small as compared with the low-pressure condensate pump 2 trip. Therefore, the suction pressure of the turbine-driven feed water pump 13 does not fall below the trip set value due to the high-pressure condensate pump 8 trip, and the possibility that the turbine-driven feed water pump 13 automatically stops is low. However, it is preferable to improve the stability of plant operation.

  When the condensate pump preliminary machine continuous operation function 22 is activated, three high-pressure condensate pumps 8 to 10 are in an operating state. When the high pressure condensate pump 8 trips in this state and the two high pressure condensate pumps 9 and 10 continue to operate, the interlock function 21 does not operate.

  Since the discharge flow rates of the high-pressure condensate pumps 9 and 10 in the two-unit operation state are increased, the heads of the high-pressure condensate pumps 9 and 10 are lowered according to the pump characteristics. As a result, the suction pressure of the turbine drive feed pumps 12 and 13 on the downstream side decreases. However, the degree of pressure drop is small compared to when the condensate pump preliminary machine continuous operation function 22 is not activated.

  Furthermore, since the suction pressure of the turbine-driven feed water pump 13 is higher than usual in the normal operation state (when the condensate pump preliminary machine continuous operation function 22 is not activated) (see FIG. 8A), the high-pressure condensate pump 8 trips. Therefore, even if the suction pressure of the turbine-driven feed water pump 13 slightly decreases, there is almost no effect.

~effect~
The effect of this embodiment will be described by comparing the time when the condensate pump preliminary machine continuous operation function 22 is not operated (operation 2) and the time when the condensate pump preliminary machine continuous operation function 22 is operated (operation 3).

  When the condensate pump preliminary machine continuous operation function 22 is not activated, the low-pressure condensate pumps 2 and 3 and the high-pressure condensate pumps 8 and 9 are in an operating state. As a result, the pump head is lowered, and as a result, the suction pressure of the turbine-driven feed water pumps 12 and 13 is reduced even during normal operation as compared to during rated operation. In this state, when the low pressure condensate pump 2 trips and the interlock function 21 is activated, the suction pressure of the turbine-driven feed water pump 13 is further reduced and falls below the trip set value, and the turbine-driven feed water pump 13 may automatically stop. (See FIGS. 6B and 7B).

  When the condensate pump preliminary machine continuous operation function 22 is activated, the low-pressure condensate pumps 2 to 4 and the high-pressure condensate pumps 8 to 10 are in the three-unit operation state, and the head of each pump is increased as compared with the two-unit operation state. As a result, even during normal times, the suction pressure of the turbine-driven feed water pumps 12 and 13 increases compared to the two-unit operating state (see FIG. 8A). Thereby, even if the low pressure condensate pump 2 is tripped, the high pressure condensate pump 8 is automatically stopped by the interlock function 21, and the suction pressure of the turbine driven feed water pump 13 is reduced, the trip set value is not lowered. There is no possibility that the turbine-driven feed water pump 13 is automatically stopped.

  Furthermore, even if the low-pressure condensate pump 2 trips and the high-pressure condensate pump 8 is automatically stopped by the interlock function 21, there is no possibility of cavitation occurring in the turbine-driven feed pumps 12 and 13 on the downstream side. When the low-pressure condensate pump 2 trips and the high-pressure condensate pump 8 automatically stops, the low-pressure condensate pumps 2, 3 and the high-pressure condensate pumps 2, 3 and The heads of the condensate pumps 9 and 10 are lowered. As a result, the suction pressure of the turbine-driven feed water pumps 12 and 13 decreases. However, comparing the case where two condensate pumps are one (operation 2) and the case where two condensate pumps are two (operation 3), the discharge flow increases in the case of operation 3. Is less. Therefore, the degree of pressure drop is small compared to when the condensate pump preliminary machine continuous operation function 22 is not activated.

  To summarize the above two points, when the condensate pump preliminary machine continuous operation function 22 is activated, the suction pressure of the turbine-driven feed water pumps 12 and 13 during normal operation is compared with that when the condensate pump preliminary machine normal operation function 22 is not activated. Turbine driven due to the fact that the suction pressure drop of the turbine-driven feed water pumps 12 and 13 is small even when the low-pressure condensate pump 2 trips, compared to when the condensate pump preliminary machine continuous operation function 22 is not activated. The suction pressure of the feed water pump 13 never falls below the trip set value, and there is no possibility that the turbine-driven feed water pump 13 automatically stops (see FIGS. 8B and 9B).

  Thereby, even when the low pressure condensate pump 2 trips during the heat output improvement operation, the plant operation can be stably continued.

  Further, when the high-pressure condensate pump 8 trips when the condensate pump spare machine continuous operation function 22 is not activated, the turbine-driven feed water pump 13 is unlikely to automatically stop. When is operated, plant operation can be continued more stably.

-Confirmation of plant stable operation continuity-
The present embodiment is characterized in that the condensate pump preliminary machine continuous operation function 22 is activated, and the low-pressure condensate pump 4 and the high-pressure condensate pump 10 that are spare machines are in a normal operation state as a regular machine. From a different perspective, there seems to be no need for spare machines, and it seems necessary to add spare machines from the viewpoint of continuing stable plant operation.

  However, when the condensate pump preliminary machine continuous operation function 22 is not operated, when the low-pressure condensate pump 4 and the high-pressure condensate pump 10 are used as spare units (operation 2), there is a risk of loss of all feed water. When the spare machine always-on function 22 is activated (operation 3), an effect that the plant operation can be continued stably is obtained.

  That is, not only the conventional stable drivability is ensured, but as a result, the stable drivability is further improved.

~ Another effect ~
Another effect of this embodiment will be described.

  During the heat output improvement operation, the feed water flow rate increases in conjunction with the output increase as compared to the rated output operation (see FIG. 9A). The turbine-driven feed water pumps 12 and 13 adjust the rotation speed and adjust the feed water flow rate. However, the capacity of the turbine-driven feed water pumps 12 and 13 has a limit, and depending on the degree of increase in the feed water flow rate, the required number of revolutions exceeds 100%, and there is a problem that cannot be dealt with by adjusting the number of revolutions alone. .

  FIG. 10 is a diagram showing the relationship between the feed water flow rate and the heads of the turbine-driven feed water pumps 12 and 13.

  The turbine-driven feed water pumps 12 and 13 adjust the number of rotations to control the feed water flow rate. The rotation speed is determined by selecting a pump characteristic that passes through the intersection of the feed water flow rate and the required head characteristic. The necessary head is a head necessary for the turbine-driven feed water pumps 12 and 13 to feed water to the reactor, and is a difference between the feed water pump discharge pressure and the feed water pump suction pressure. The necessary head characteristic has a characteristic that, when the feed water flow rate increases, the feed water pump suction pressure decreases and the feed water pump discharge pressure increases to increase. The required head characteristics when the condensate pump preliminary machine continuous operation function 22 is not operated are the first required head characteristics shown in the figure. The pump characteristics have been described with reference to FIG.

  For example, when the feed water flow rate at the time of rated output (100% output) operation is determined, the intersection point X with the first required head characteristic is determined, and the pump characteristic of 80% rotation speed passing through the intersection point X is selected. That is, the turbine drive feed pumps 12 and 13 are adjusted to 80% rotation speed.

  During the heat output improvement operation, the feed water flow rate increases compared to the rated output operation. When the feed water flow rate at the rated output operation is determined, the intersection point Y with the first required head characteristic is determined, and the 120% rotation speed pump characteristic passing through the intersection point Y is selected. However, the capacity of the turbine-driven feed water pumps 12 and 13 is up to 100% rotation speed, and water cannot exceed the limit feed water flow rate. The limit water supply flow rate is a water supply flow rate corresponding to 100% rotation speed.

  In response to this problem, it may be possible to replace the water pump with a high capacity. For example, the turbine-driven feed water pumps 12 and 13 are updated to pumps having a capacity corresponding to 120% rotation speed. However, it is against the idea of making effective use of existing nuclear power plants.

  In this embodiment, the condensate pump preliminary machine continuous operation function 22 is activated, and the low-pressure condensate pumps 2 to 4 and the high-pressure condensate pumps 8 to 10 are in the three-unit operation state, and each pump is compared with the two-unit operation state. As a result, the state in which the suction pressure of the turbine-driven feed water pumps 12 and 13 is increased as compared with the two-unit operation state is maintained even during normal operation (see FIG. 8A).

  By the way, the reactor pressure is the same whether in a three-unit operation state or in a two-unit operation state. An increase in the suction pressure of the turbine-driven feed water pumps 12 and 13 can be rephrased as a decrease in the required head of the turbine-driven feed water pumps 12 and 13. The required head characteristic when the condensate pump preliminary machine continuous operation function 22 operates is the second required head characteristic shown in the figure.

  When the feed water flow rate during the heat output improvement operation is determined, the intersection Z with the second required head characteristic is determined, and the pump characteristic of 100% rotation speed passing through the intersection Z is selected. That is, water can be fed within the capacity range of the turbine-driven feed water pumps 12 and 13.

  Thereby, at the time of heat output improvement operation, the above-mentioned subject accompanying increase in feed water flow rate can be solved while using existing turbine drive feed pumps 12 and 13 effectively.

Second Embodiment
In the first embodiment, the condensate pump preliminary machine continuous operation function 22 is configured to always operate the low-pressure condensate pump 4 and the high-pressure condensate pump 10 that were spare machines during the rated output operation during the heat output improvement operation. Although controlled, in this embodiment, the condensate pump preliminary machine continuous operation function 22A controls the low-pressure condensate pump 4 that was a standby machine during the rated output operation so as to always operate during the heat output improvement operation. The high-pressure condensate pump 10 is in a standby state as a spare machine even during the heat output improvement operation.

  The operation of the water supply operation system when the condensate pump preliminary machine continuous operation function 22A is activated will be described.

  When the low-pressure condensate pump 2 trips, the low-pressure condensate pumps 3 and 4 continue to operate, and two units are in operation. There is no imbalance in the number of operating units between the upstream low pressure condensate pumps 3 and 4 and the high pressure condensate pumps 8 and 9, and the interlock function 21 does not operate. It becomes the state similar to the operation | movement 3 of 1st Embodiment, the suction pressure fall of the turbine drive feed pump 13 is slight, and a plant operation can be continued stably. That is, the same effect as the first embodiment can be obtained.

  When the high-pressure condensate pump 8 trips, one high-pressure condensate pump 9 continues to operate, and the interlock function 21 is activated. As described in the non-operation of the condensate pump preliminary machine continuous operation function 22 of the operation 4 of the first embodiment, the degree of the suction pressure drop of the turbine driven feed water pump 13 is small compared to when the low pressure condensate pump 2 trips. . Although the effect of the first embodiment cannot be obtained, the suction pressure of the turbine-driven feed water pump 13 does not fall below the trip set value due to the trip of the high-pressure condensate pump 8, and there is no possibility that the turbine-driven feed water pump 13 automatically stops.

  Thereby, the plant operation can be stably continued even during the heat output improvement operation.

1 Condenser 2, 3 Low pressure condensate pump (common use machine)
4 Low pressure condensate pump (spare machine)
5 Air extractor condenser 6 Ground steam condenser 7 Condensate filtration / desalination equipment 8, 9 High-pressure condensate pump (ordinary machine)
10 High pressure condensate pump (spare machine)
DESCRIPTION OF SYMBOLS 11 Low pressure feed water heater 12, 13 Turbine drive feed pump 14, 15 Electric motor drive feed pump 16, 17 Feed water control valve 18 High pressure feed water heater 19 Reactor 20 Controller 21 Interlock function 22 Condensate pump spare machine always running function

Claims (3)

A condenser that condenses the steam,
A condensate pump that boosts the condensate condensed in the condenser, includes a plurality of regular machines and spare machines, and these are arranged in parallel;
Installed downstream of this condensate pump, further boosting the discharge water of the condensate pump and sending it to the reactor, including a plurality of regular machines and spare machines, these being arranged in parallel,
A control means for controlling the condensate pump and the feed pump;
When one of the condensate pumps is tripped, the control means detects an imbalance between the number of the condensate pumps and the feed pumps and automatically stops one of the feed pumps. In the water supply operation system of a nuclear power plant having an interlock function for automatically starting the feed water pump spare machine after automatically starting the condensate pump spare machine,
The water supply operation system for a nuclear power plant, wherein the control means has a condensate pump spare machine continuous operation function for constantly operating the condensate pump spare machine during a heat output improvement operation. The plurality of condensate pumps include a plurality of regular machines and spare machines, and these are installed in parallel with a low-pressure condensate pump, and a plurality of regular machines and spare machines. A high-pressure condensate pump in which these are arranged in parallel,
The interlock function of the control means detects an imbalance in the number of operating units of the low-pressure condensate pump, the high-pressure condensate pump and the feed water pump when one of the low-pressure condensate pump regular machines trips. One of the high pressure condensate pump regular machines is automatically stopped, one of the feed water pump regular machines is automatically stopped, and the low pressure condensate pump spare machine is automatically started, and then the high pressure condensate pump spare machine is Automatically start the water supply pump spare machine,
A water supply operation system for a nuclear power plant characterized in that the condensate pump spare machine always-operating function of the control means always operates at least the low-pressure condensate pump spare machine at the time of heat output improvement operation. A condenser for condensing steam, a condensate condensed by the condenser, and a condensate pump including a plurality of regular machines and spare machines arranged in parallel, and a downstream of the condensate pump The water supply of a nuclear power plant including a plurality of regular machines and spare machines, which are arranged in parallel, and which further boosts the discharge water of the condensate pump and sends it to the reactor, and these are arranged in parallel A system operating method,
During rated output operation, when one of the condensate pump regular machines trips, the interlock function of the water supply system is activated to automatically stop one of the feed water pump regular machines, and the condensate pump spare In the operation method of the nuclear power plant water supply system that automatically starts the water pump preliminary machine after the machine is automatically started,
A method of operating a water supply system for a nuclear power plant, wherein the condensate pump spare machine is always operated during a heat output improvement operation.

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