JPH0740076B2 - Pump drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pump drive device suitable for use in circulating a reactor coolant, and more particularly to a pump drive device capable of adjusting the rotation speed of the pump when the pump is stopped.

The reactor coolant main circulation pump circulates an appropriate amount of coolant through the core to maintain the core at an appropriate temperature. When the main circulation pump trips, the coolant flow rate gradually decreases due to the rotational inertia of the pump, and the reactor is scrammed. Fig. 1 shows the relationship between the coolant flow rate in the core and the output of the nuclear reactor at this time.

As shown in Fig. 1, the core coolant flow rate starts to decrease earlier than the reactor scram time, so a mismatch occurs between the core coolant flow rate and the reactor output, and the temperature of the fuel cladding tube is temporarily increased. May rise. Therefore, a flywheel is provided so that the rate of decrease in the core coolant flow rate and the reactor output match, so that the rotational speed of the pump decreases slowly. This will be described with reference to FIG.

In FIG. 2, a pump body 10 of the main circulation pump (P) is provided with a coolant inlet 12 and a coolant outlet 14. A drive motor (M) 18 is attached to the pump rotor 16, and a flywheel (F, W) 20 is attached to increase the rotational inertia of the pump rotor 16. The pump rotor 16 to which the drive motor 18 and the flywheel 20 are attached is axially supported by the thrust bearing 24 fixed to the floor portion 22, and the entire load of the pump rotor 16 is applied to the thrust bearing 24.

In the pump drive device configured as described above, when the pump trips, the reactor scrams, and due to the large rotational inertia of the flywheel 20, the rotational speed of the pump decreases slowly. Therefore, the coast down of the coolant flow rate of the core becomes slow, and the core can be sufficiently cooled. However, assuming a serious accident in which the core coolant flow rate suddenly decreases, such as the coolant flowing out to the outside, even in this case, the rotational inertia that can secure the coolant flow rate that ensures the integrity of the core is sufficient. To add, a very large flywheel must be installed. Therefore, there are drawbacks that an excessive load is applied to the thrust bearing 24 and the size of the device becomes large.

On the other hand, in a fast breeder reactor or the like that uses liquid metal as a coolant, if the rotational inertia of the flywheel 20 is too large, the output decreased due to the scrum except in the case of an accident in which the coolant flow rate of the core rapidly decreased. After that, the coolant flow rate in the core does not decrease so much. for that reason,
When a low-temperature coolant flows into the hot-leg equipment, piping, etc., thermal shock is given to these equipment, piping, etc. Therefore, except for a serious accident in which the coolant flow rate in the core rapidly decreases, it is preferable to delay the decrease in the coolant flow rate by giving the pump rotor 16 more rotational inertia than necessary when the pump trips. Absent.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and properly control the rotational speed of the pump when the pump trips.

The present invention relates to a first electric motor and a flywheel connected to a pump shaft, a generator that supplies current to the first electric motor, a second electric motor that drives the electric generator, and a second electric motor. In a pump drive device including an exciter that is directly connected to supply an exciting current to the generator, at least one of a trip signal that trips the pump and a pipe major damage signal that detects major damage to a pipe connected to the pump To cut off the power supply to the second electric motor, a means to input a pump trip signal to cut off the exciting current of the generator, and a means to input a large pipe damage signal to cut off the exciting current by the pump trip signal. And a means for erasing the release command of.

A preferred embodiment of a pump driving device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is an explanatory diagram of an embodiment of the pump drive device according to the present invention.

A drive motor 18 for driving the main circulation pump P in FIG.
Receives electric current from the generator (G) 26. The generator 26 receives a working fluid from a generator motor (M) 30 via a variable speed fluid coupling (FC) 28 and is rotationally activated. The generator 26 is the generator motor 30.
A field current is received by a field winding 36 from a field exciter (EX) 32 directly connected to the field winding and a disconnector 34.

The generator motor 30 is electrically connected to the in-house power source bus 40 via a power source and a breaker 38. The power switch and breaker 38 can be opened by a control circuit 42 such as an or circuit as shown by a broken line in the figure. This control circuit 42 has a pump trip signal 44 and a pipe major damage signal 46.
And are entered. The pump trip signal 44 also opens the field breaker and the disconnector 34, and the large piping damage signal 46 erases the command of the pump trip signal 44 to open the field breaker and the disconnector 34 (W, O). It is becoming like this.

The operation of the embodiment configured as described above is as shown in the drawing.

The generator motor 30 rotates by receiving current from the in-house power source bus 40, sends working fluid to the generator 26, and excites the exciter machine.
A field current is applied to the generator 26 via 32. The flow rate of the working fluid that starts the generator 26 is adjusted by the variable speed fluid coupling 28, and the amount of current generated by the generator 26 is adjusted to drive the drive motor.
The rotational speed of the main circulation pump P is controlled via 18.

Then, when the pump trip signal 44 is transmitted, the reactor is scram
The power supply 44 and the circuit breaker 38 are opened via the control circuit 42, and the field breaker and the circuit breaker 34 are opened. Therefore, the generator 26 stops supplying the drive current to the drive motor 18, and the rotation speed of the main circulation pump P gradually decreases due to the rotation inertia of the flywheel 20 as described in the prior art. .
For this reason, during normal pump trip, an excessive coolant flow rate is not supplied to the core, so that low-temperature coolant does not flow into the reactor hot-leg equipment, piping, etc. Can be prevented.

In the unlikely event of major damage to the main cooling system piping that would cause the coolant to flow out of the reactor vessel, the coolant that flowed out of the reactor vessel should be placed in a safety container provided outside the reactor vessel. It flows in and the reactor scrams. Then, the pump trip signal 44 and the pipe major damage signal 46 are input to the pump drive device. For this reason, the power supply / breaker 38 is opened, and the supply of current to the generator motor 30 is stopped. However, the field trip by the pump trip signal 44 and the opening command of the circuit breaker 34 are
Cleared by pipe breakage signal 46, exciter 32 and generator 26
The field winding 36 is maintained in an electrically connected state.
Therefore, the generator 26 does not stop power generation immediately, but continues power generation for a certain period of time. That is, the generator motor 30 continues to rotate due to its own rotational inertia even after the current supply is stopped.
The working fluid is continuously supplied to the field winding 36 and the field current is supplied to the field winding 36 via the exciter 32. For this reason, the rate of decrease in the number of revolutions of the main circulation pump P is delayed, and a sufficient coolant is supplied to the core unlike in the case of a normal pump trip. It should be noted that by turning on the power source and opening the disconnector 38, the driving force of the generator motor 30 is suppressed to some extent, and due to the large discharge pressure of the main circulation pump P, the coolant that has flowed out of the reactor vessel is the upper end of the safety vessel. To prevent it from overflowing.

FIG. 4 is an explanatory view of another embodiment of the pump drive device according to the present invention.

In the embodiment shown in FIG. 4, a field regulator 48 is provided in place of the field breaker / breaker 34 shown in FIG. That is, during a normal pump trip, the pump trip signal 44 is used to turn on the power supply, open the breaker 38, and activate the field regulator 48. When the field controller 48 receives the pump trip signal 44, the amount of the coolant discharged from the main circulation pump P satisfies the limits of the core fuel cladding tube temperature and the thermal shock of the hot-leg equipment and piping. In this way, the field current applied to the field winding 36 is controlled. That is, the pump trip signal 44
Is input to the field controller 48, the temperature of the core, the temperatures of the equipment and piping of the hot leg, and the temperature of the coolant are input to a control device (not shown). The control device (not shown) uses the above-mentioned temperature signals at each time to control an excessive flow rate of the coolant that causes a temperature rise in the core fuel cladding tube and an excessive flow rate that causes a thermal shock to the hot-leg equipment and piping. calculate. Then, the control device controls the circulation pump P.
Is compared with the calculated underflow rate and overflow rate, and a current is supplied to the field controller 48 so that the delivery rate of the main circulation pump P is within the underflow rate and overflow rate ranges. The amount of power generated by the generator 26 is controlled via the field current that is adjusted and applied to the field winding 36.

If a major breakage occurs in the main cooling system piping, a major piping breakage signal 46 is input to the field controller 48. Field controller 48
When the pipe major damage signal 46 is input to, the control device (not shown) adjusts the amount of current supplied to the field controller 48 so that the discharge amount of the main circulation pump P is maximized, and the field winding 36 is supplied to the field winding 36. The applied field current is maximized to prevent a sharp decrease in the core coolant flow rate.

In the above embodiment, the case where the field current applied to the field winding 36 is controlled has been described, but the variable speed fluid coupling 28 is controlled and the amount of power generation is controlled by the working fluid of the generator 26. Good.

According to the present invention, when the pump trips, the excitation current of the power supply of the second electric motor and the generator is cut off, so that the pump can be stopped while controlling the rotation speed to an appropriate value by the flywheel.

In the unlikely event that the pump pipe is severely damaged, the power of the second electric motor is cut off and the opening command of the exciting current cut-off means is erased, so that the generator has the rotational inertia of the generator itself and the second electric motor. By returning the exciting current, it is possible to continue power generation and delay the decrease in the pump rotation speed.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship among reactor output, core coolant flow rate and fuel cladding temperature during pump trip, FIG. 2 is a rotary inertia adjusting device in a conventional pump drive device, and FIG. 3 is a diagram relating to the present invention. FIG. 4 is an explanatory view of an embodiment of the pump drive device, and FIG. 4 is an explanatory view of another embodiment of the pump drive device according to the present invention. 10 …… Pump body, 18 …… Drive motor, 26 …… Generator,
30 …… motor for generator, 32 …… exciter, 36 …… excitation winding, 38 …… power supply and disconnector, 44 …… pump trip signal,
46 …… Signal for major pipe damage, P …… Main circulation pump.

Claims (1)

[Claims] 1. A first electric motor and a flywheel connected to a pump shaft, a generator for supplying a current to the first electric motor, a second electric motor for driving the electric generator, and a second electric motor. In a pump drive device directly connected to the exciter for supplying an exciting current to the generator, at least one of a trip signal that trips the pump and a pipe major damage signal that detects major damage to a pipe connected to the pump Means for inputting one of the signals to cut off the power supply to the second electric motor; means for inputting the pump trip signal to cut off the exciting current of the generator; and inputting the pipe major damage signal to input the pump trip signal. And a means for erasing the opening command for the exciting current cutoff means by the pump driving apparatus.