JPS6311897A - Boiling water type nuclear power 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] [Object of the Invention] (Industrial Application Field) The present invention relates to a PM wooden nuclear power plant, and particularly to a boiling water nuclear power plant that automates switching operation of a feed water pump during reactor scram. Regarding.

(Prior art) In general, in a boiling water nuclear power plant, the water pump that supplies reactor water to the reactor accounts for approximately 50% of the total pump capacity.
It has two turbine-driven wJ reactor feed pumps (T/DRFP), and two electric motor-driven reactor feed pumps (M/DRFP) with a capacity of approximately 25% for backup purposes. During reactor operation, two turbine-driven reactor feed water pumps are operated to maintain the reactor water level.

In addition, a pump interlock is provided to prevent automatic activation of the Tanabata-driven reactor water bomb when the turbine-driven reactor water pump is stopped, thereby backing up the turbine-driven reactor water pump.

However, if a reactor scram occurs for some reason, the reactor water level behaves roughly as shown in FIG. 4.

That is, as shown in FIG. 4, at time t. When a reactor scram occurs at , the voids within the reactor decrease due to a sudden drop in the core calorific value, and the reactor water level X temporarily drops to the lowest water level at , for example.

However, after that, the voids increase again due to the decay heat of the core, so the reactor water level starts to rise (time 1 - 12).
If this state is left as it is, the water pump trip level x61 will eventually be reached, and the pump interlock will operate, stopping all reactor water pumps.

Therefore, in conventional boiling water nuclear power plants, before the reactor water level reaches the feed water pump trip level The reactor water level is prevented from reaching the feedwater pump trip level xl by automatically starting the capacity electric motor-driven reactor feedwater pump and reducing the feedwater flow rate to the reactor.

FIG. 3 shows the procedure for switching the operation of the reactor feed water pump by manual operation during plant operation Q, and the reactor scram occurs at time t. The reactor water level was at its lowest level. decreases to
After that, at time t3 when the reactor water level starts to rise and recovers to the required reactor water level x 1, one of the two turbine-driven reactor feed water pumps in operation is first tripped. If one of the turbine-driven reactor feedwater pumps in operation trips, two of the motor-driven reactor feedwater pumps will automatically start due to the pump interlock. Therefore, at time t3, the total reactor feed water pump capacity is 100%.

Therefore, as in the case shown in Fig. 4, the reactor water level continues to rise, and at time t4 when the next reactor water level x 2 is reached, the plant operator manually operates the second turbine-driven reactor feed water pump. to trip.

As a result, after time t4, only two motor-driven reactor feed water pumps (50% of all pump failures in total) are operated, so the flow rate of water supply to the reactor decreases and the reactor water level drops to the water pump trip. It is possible to prevent the level from rising to level X.

(Problem to be Solved by the Invention) However, due to the rapid behavior of the reactor water level shown in Figure 4, within a short time after the reactor scram occurs, the plant operating port must perform the above-mentioned switching operation of the feed water pump. must be carried out quickly and manually, placing a heavy burden on plant operators.

In addition, if there is an error or delay in these manual operations, the reactor water level will quickly reach the feed water pump trip level xIIl, which may cause a loss of water supply due to all water pumps being stopped.

In this way, the plant operator's hand v during the reactor scram
J! Switching of water supply pump operation by & is plant operation ξ
This is putting an excessive burden on K.

Therefore, an object of the present invention is to provide a boiling water nuclear power plant that reduces the burden on plant operators and improves plant safety by automatically switching the operation of the reactor feed water pump during reactor scram. shall be.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a turbine-driven nuclear reactor feed water pump that supplies reactor water to a nuclear reactor, and a smaller-capacity electric motor for backing up this turbine-driven reactor water pump. Detecting occurrence of reactor scram in a boiling water nuclear power plant having a driven nuclear reactor feed pump and a pump interlock that automatically starts the FFI 11 driven reactor water pump when the turbine driven reactor feed pump is stopped. A feedwater pump operation control 111Q path 1 was provided for automatically stopping the operation of the child reactor feedwater pump in the turbine drive IIIj) when the above-mentioned turbine drive IIIj) occurred.

(Function) During normal operation of the reactor, the turbine-driven reactor feed water pump is operated.

However, when a reactor scram occurs, the feedwater pump operation control circuit automatically stops the operation of the turbine-driven reactor feedwater pump. This causes the pump interlock to automatically start the motor-driven reactor feed water pump.

Therefore, during a reactor scram, the operation is switched from the turbine-driven reactor feed water pump to the smaller-capacity electrically driven reactor water pump, which reduces the flow rate of water supply to the reactor and prevents an abnormal rise in the reactor water level. Can be done.

Furthermore, since the operation of the reactor feed water pump is automatically switched between turbine-driven and electric motor-driven, the burden on plant operators can be reduced and the safety of the plant can be improved.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 3.

FIGS. 1(A) and 1(B) show all units in one embodiment of the present invention,
For example, this example shows a water pump operation control circuit that outputs both A and B trip signals to automatically stop (trip) two turbine-driven nuclear reactor feed water pumps A and B. In this example, the conventional example described above is shown. A turbine-driven reactor feed water pump (abbreviated as T/DRFP) similar to the above, and a small-capacity electric motor-driven reactor feed water pump (abbreviated as M /DRF+)) and a pump interlock that automatically starts the motor-driven reactor feed water pump when the turbine-driven reactor feed water pump is stopped.

However, similar to the conventional example, this embodiment has two turbine-driven reactor feed water pumps, each having, for example, 50% of the total pump capacity, and an electric motor-driven reactor water pump having a capacity of 25% of the total pump capacity. % of the equipment. In addition, each turbine-driven nuclear reactor feed water pump and each electric motor-driven reactor feed water pump correspond to each other on a one-to-one basis, and when each turbine-driven reactor feed water pump trips, the operation of a pump interlock (not shown) is activated. Each electric reactor feedwater pump is automatically started.

The A and B logic circuits 10 and 20 that output both the A and B trip signals are configured as shown in FIGS.
, 82.83.84 and S5 signals as inputs.

That is, the first AND gate 11 receives the S1 signal and the first
The logic outputs of the OR gate 12 and the second OR gate 13 are input, and the first OR gate 12 has an input of 82.
84.35 to the second OR gate 13.
give a signal.

The S1 signal is a reactor scram signal 31. which is output when a reactor scram occurs, as shown in FIG. 2(A). And reactor water level ≦xo. The signal Sli is output from the second AND gate 14 to which the signal Sli is applied.

Reactor water level ≦X of xo0 signal. 0 is X shown in FIG. It is set slightly higher than the water level, and X o□ < X 1
<X It is set so that formula 2 holds true. here,
×1 and ×2 indicate ×1 and ×2 in FIG. 3.

Also, the reactor water level≦xo. Since the signal is given to the second AND gate 14 through the self-holding circuit 15 having an OR gate, once the reactor water level reaches X as shown in FIG. . If the reactor water level falls below this level, even after the reactor water level recovers, this reactor water level≦xo. The output of the signal is retained.

The above S2 signal is connected to the M/DRFP as shown in Fig. 2(B).
This is a waiting signal for one or more units, and this is a signal for two M/DRFPs.
This is a signal that is output when at least one of the devices is in a state where it can be automatically started by a start signal.

When one or two motor-driven nuclear reactor feed water pumps are in operation, a signal S3 indicating that one or more M/DRFPs are in operation is output. These signals 82 and 83G are given to the first OR gate 12 of the A logic circuit 10 shown in FIG. The signal is applied to the first AND gate 11.

The S4 signal is the two T/DRFP operating signal 34. as shown in FIG. 2(C). Since this is a logic signal output from the third AND gate 16 to which the reactor water level ≧×1 signal 34 is given, the two turbine-driven reactor feed water pumps A
As shown in FIG. 3, the reactor water level is recovered by the operation of B and B, and an output is made when the reactor water level reaches x1 or more.

The S5 signal is T/D RF as shown in Figure 2(D).
Since the P-A operating signal S5 and the reactor water level ≧×2 signal 85 are output from the fourth AND gate 17, the two turbine-driven reactor feed water pumps A and B are It is output when one of them is in operation and the reactor water level reaches the reactor water level X2 or higher shown in FIG. 3.

The logic circuit 10 configured in this manner applies an A trip signal to one of the turbine-driven reactor feed water pumps to automatically trip the operation.

On the other hand, the B logic circuit 20 is configured as shown in FIG. 1(B), and outputs an 8-trip signal when the logic signals 81, 83 and the S6 signal are simultaneously applied to the fifth AND gate 21. This B trip signal is applied to the other turbine driven reactor feed pump 8 to automatically trip its operation.

The above S6 signal is transmitted to the T/DRFP as shown in Fig. 2 (E).
-43 operating signal S6 and reactor water level≧x2 signal 86. is a logic signal that is output when both are simultaneously applied to the sixth AND gate 22, and when the reactor water level reaches the reactor water level x2 or higher shown in Fig. 3 due to the operation of the turbine-driven reactor feed water pump, the other B. is output to.

Next, the operation of this embodiment will be described.

While operating, for example, two turbine-driven reactor feed pumps (T/DRFP), A and B, a reactor scram occurs for some reason, and the reactor water level temporarily drops to X as shown in Figure 3. . When the reactor scram signal falls below 81. and reactor water level≦Xoo signal q are both applied to the second AND gate 14, so the S1 signal is output.

Reactor water level≦xoo In MS1b, the water level is once Xo. (3rd
(See figure) If the reactor water level drops below
. .

Even if it recovers by rising above that level, its output will be maintained.

When the reactor water level reaches x1 or more, the third AND gate 16
When the AND condition is satisfied, the S4 signal is output, thereby satisfying the OR condition of the second OR gate 13.

At this point, two motor-driven reactor feed water pumps (M/D
If at least one of the RFPs is in a standby state, that is, in a state where it can be automatically started by a start signal, the S2 signal is output, so the OR condition of the first OR gate 12 is satisfied.

As a result, the logic signal from the first and second OR gates 12-13 and the 81 signal are applied together to the first AND gate 11, and the A I-rip signal is output.

The A-trip signal is applied to one of the turbine-driven reactor feedwater pumps, tripping its operation.

When one of the turbine-driven reactor feed water pumps A trips, the two smaller-capacity motor-driven reactor feed water pumps A and B are automatically started by a pump interlock.

Furthermore, when the reactor water level rises and reaches x2 or higher, the AND condition of the sixth AND gate 22 is satisfied and the S6 signal becomes m
Moreover, since the motor-driven reactor feed water pump △, 8 has already started automatically and is in operation, the
) satisfies the AND condition of the fifth AND gate 21, and the B trip signal is applied to the other B of the turbine-driven full reactor feed water pumps, tripping its operation.

In this way, during a reactor scram, the operation of the two turbine-driven reactor feed water pumps A and B is automatically stopped at an appropriate timing, while the two smaller-capacity electric e II-driven reactor feed pumps A , B are both automatically activated by a conventional pump interlock.

Therefore, according to this embodiment, since the feed water flow Gl to the reactor is reduced when a reactor scram occurs, the rise in the reactor water level is suppressed as shown in FIG. 3, and the feed water pump trip level X is lowered. The water level was suppressed and all water pumps were not forced to stop.

As explained above, in this embodiment, a case has been described in which a plurality of units, for example, two turbine-driven water supply pumps, are used to perform 100% capacity operation during normal reactor operation. It is not limited to this,
For example, it can be applied to a case where 100% water supply operation is performed during normal quick drying of the reactor using one turbine-driven reactor feed water pump and two electric motor-driven reactor feed water pumps; in this case, Either the A or B trip signals can trip the turbine-driven reactor feedwater pump that is in operation. That is, △
If B is in operation, the A trip signal is output by the SL, 83°S5 signal, and if B is in operation, 82.83.8
B trip is output by the 6 signal.

〔Effect of the invention〕

As explained above, the present invention automatically stops the operation of the turbine-driven reactor feed water pump using the feed water pump operation control circuit as soon as a reactor scram occurs, and uses the conventional pump interlock to automatically stop the operation of the turbine-driven reactor feed water pump. The motor-driven pump can be automatically started.

Therefore, according to the present invention, during a reactor scram, the feedwater pump operation control circuit can automatically switch the operation between the turbine-driven reactor feedwater pump and the motor-driven reactor feedwater pump, thereby reducing the burden of zero plant operation. It is possible to reduce this and prevent intervention due to an erroneous operation during blunt operation 0, thereby improving the safety of the plant.

[Brief explanation of the drawing]

FIGS. 1(A) and 1(B) are logic circuit diagrams respectively showing the feed water pump operation control circuit in an embodiment of the boiling water nuclear power plant according to the present invention, and FIGS. 2(A>(B)(C)(
D) (E) is a diagram showing the signal input to the feedwater pump operation υIn circuit shown in FIG. 1 and the logic circuit that forms the signal, respectively. FIG. 3 is a diagram showing the nuclear reactor in the embodiment shown in FIG. 1. FIG. 4 is a graph showing the behavior of the reactor water level during a scram together with a conventional example. FIG. 4 is a graph showing the behavior of the reactor water level when water supply control is not performed during the reactor scram. 10... logic circuit, 11... first AND)
gate, 12...first OR gate, 13...second
OR gate, 20...80 chic circuit. Applicant's agent Hisashi Hatano (, 4)
Tea 1 Figure 1-■----'----- Certain 3 Kunikozue Tea 4 Figure

Claims (1)

[Claims] A turbine-driven nuclear reactor feed water pump that supplies reactor water to the reactor, an electric motor-driven reactor water pump that is used as a backup for the turbine-driven reactor water pump and has a smaller capacity, and the turbine-driven reactor water pump. In a boiling water nuclear power plant, the boiling water nuclear power plant has a pump interlock that automatically starts the electric motor-driven reactor feed water pump when the turbine-driven reactor feed water pump is stopped, and the pump interlock includes a pump interlock that automatically starts the turbine-driven reactor feed water pump when the occurrence of a reactor scram is detected. A boiling water nuclear power plant characterized by being equipped with a water supply pump operation control circuit that automatically stops the operation of the boiling water type nuclear power plant.