JPH0429996B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an automatic reactor power control device suitable for preventing nuclear power output fluctuations due to rapid fluctuations in neutron detection signals due to abnormalities in neutron detectors. .

[Prior art]

In light water boiling reactors, reactor output control is performed by adjusting the position of the control rods in the reactor core and by adjusting the flow rate of the recirculation system that forcibly circulates coolant to the reactor. In heavy water-moderated light water boiling reactors, this is done by adjusting the control rod position in the reactor core and boron concentration in the reactor coolant. It's summery. Such power control of a nuclear reactor is performed by grasping the power output of a nuclear reactor by utilizing characteristics unique to the reactor such as calculation of a local power factor of the nuclear reactor and calculation of a void reactivity coefficient. These calculations of local output factors, void reactivity coefficients, etc. are usually performed by detecting the number of neutrons using a plurality of neutron detectors. In particular, in light water boiling reactors or heavy water moderation reactors,
To improve measurement accuracy, multiple neutron detectors are placed inside the reactor core, and the detection signals from each neutron detector are averaged to monitor the reactor output.

The automatic reactor output control system that monitors the reactor output described above averages the detection signals of the neutron detectors in two systems independently to improve reliability and grasps the operating status of the reactor. I have to. An example of such an automatic reactor power control device is shown in FIG.

In the reactor (not shown) in FIG. 1, there are, for example, 10A ₁ , 10A ₂ , _.
and 10B ₁ , 10B ₂ , ...10 that constitute the B system
B _o is arranged. These neutron detectors 10
A ₁ , 10A ₂ , ... 10A _o , 10B ₁ , 10B ₂ , ...
...10B _o detection signal is transmitted through amplifiers 12A and 12B
After being amplified at , the signal is input to averaging circuits 14A and 14B, which are processing devices. Average circuit 14A,
14B averages the respective input detection signals and sends an output signal to a high value priority circuit (HVG) 18 via an input buffer 16. High value priority circuit 1
8 sends a control rod insertion signal to the control rod drive control circuit 20 when either one of the output signals of the averaging circuits 14A, 14B becomes larger than a predetermined value. And the control rod drive control circuit 20
The control rod drive device 24 is driven via the M station (automatic/manual switch) 22, and control rods (not shown) are inserted into the reactor core.

In the automatic reactor output control system configured as described above, for example, one of the neutron detectors in the A system may fail, and the detection signal of this failed neutron detector outputs a value smaller than the output signal that should actually be output. In this case, the high value priority circuit 18 does not operate, so that it does not lead to fluctuations in the reactor output. In such a case, when the reactor output increases more than necessary, the output value of the average circuit 14B of the B system increases, and the high value priority circuit 18 operates to automatically insert the control rods. . However, due to a failure in one of the neutron detectors in system A, the averaging circuit 14 of system A
The output signal of A becomes higher than the output state of the reactor, and even though the output of the reactor is normal, the high value priority circuit 18 is activated, automatically inserting the control rod into the reactor, and shutting down the nuclear reactor. Vary the furnace output. In addition, as described in Japanese Patent Application Laid-open No. 51-62297, in the method of detecting whether the detected output of each neutron detector exceeds the predicted value of the power distribution in the reactor,
It takes time to detect a failure in a neutron detector, and failure detection may be delayed.

[Purpose of the invention]

The present invention was made in order to eliminate the drawbacks of the prior art, and an object of the present invention is to provide an automatic reactor power control device that can prevent fluctuations in reactor power due to failure of a neutron detector. shall be.

[Summary of the invention]

The present invention includes a plurality of neutron detection means for detecting the operating state of a nuclear reactor, a detection signal from each neutron detection means is divided into a plurality of systems, and the levels of the input signals are averaged for each system. processing means, control rod insertion signal output means for outputting a control rod insertion signal when the level of one of the output signals of each processing means exceeds a set value, and processing of one of the processing means. A rate-of-change limiting means for limiting the rate of change in level fluctuation of the output signal of the means to a certain value or less compares the output signal of the other processing means with the output signal of the rate-of-change limiting means, and determines that the difference between the two is greater than or equal to the set value. manual operation signal output means for outputting a manual operation signal when This is an automatic reactor power control system equipped with

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of an automatic reactor power control system according to the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals are given to the parts corresponding to the parts explained in the prior art, and the explanation thereof will be omitted.

FIG. 2 is an explanatory diagram of an embodiment of an automatic reactor power control device that is the basis of the present invention. In Fig. 2, the average circuit 14A of the A system and the average circuit 14B of the B system
The output signals of these averaging circuits 14A, 14B
is input to a comparator 26 connected to
The signal is input to a high value priority circuit 18 via an input buffer 16 similar to the conventional one. Comparator 26 is connected to A/M station 22 and provides a signal to A/M station 22 to switch control rod drive 24 from automatic operation to manual operation.

The operation of the embodiment configured as described above is as follows.

When the comparator 26 receives the output signal of the A-system averaging circuit 14A and the output signal of the B-system averaging circuit 14B, it compares both output signals. This comparator 26
is adapted to give a signal to the A/M station 22 to switch the A/M station 22 to the manual side when the difference between the output signals of the averaging circuits 14A and 14B exceeds the error range. That is, when the difference between the output signal of the averaging circuit 14A and the output signal of the averaging circuit 14B exceeds a value that is appropriate for considering that the difference is due to a failure of one of the neutron detectors set in advance, A. /M Switch the station 22 to manual mode. For this reason, for example, a failure occurs in one of the neutron detectors of system A, and the average circuit 14A of system A
When the output signal of A/M station 22 becomes larger than the output circuit of B-system averaging circuit 14B, A/M station 22 is manually switched by the signal from comparator 26.
Therefore, the output signal of the averaging circuit 14A is input to the high value priority circuit 18 via the input buffer 16,
Even if a control rod insertion signal is given to the control rod drive control circuit 20, the signal from the control rod drive control circuit 20 is
The control rods are shut off at the M station 22, and are held as they are without being automatically inserted into the reactor core. Therefore, fluctuations in the reactor output due to failure of the neutron detector can be prevented, and the reliability of the nuclear reactor can be improved.

FIG. 3 shows that the automatic control device of the automatic reactor power control device according to the present invention includes neutron detectors 10A ₁ , 10A ₂ , 10B ₁ , 10B ₂ as neutron detection means,
Average circuits 14A and 14B as processing means, rate of change limiter 30 as rate of change limiter, comparator 26 as manual operation signal output means, input buffer 16 and high value priority circuit 18 as control rod insertion signal output means, and It comprises a control rod drive control circuit 20, an A/M station 22 as control rod drive means, and a control rod drive device. Then, the neutron detectors 10A ₁ , 10A ₂ , 10B ₁ , 10B ₂ are A
The signal is inputted to a system averaging circuit 14A and a B system averaging circuit 14B. This is because the absolute number of neutron detectors is small, and the neutron detectors that input the output signal to the averaging circuit 14A and the neutron detectors that input the detection signal to the averaging circuit 14B are separated, so that the average reactor output can be accurately adjusted. Since it is insufficient for good monitoring, the neutron detector is shared between the A system and the B system. In such a device, if one of the neutron detectors fails, the detection signal of that neutron detector is input to both the averaging circuits 14A and 14B.
The detection signals of both averaging circuits 14A and 14B similarly vary.

Therefore, in this embodiment, the rate of change limiter 3 provided in the comparator 28 outputs the output signal of the averaging circuit 14A.
0 to the comparator 26. The rate of change limiter 30 is designed so that when the input signal fluctuates, the signal output from the rate of change limiter 30 always increases or decreases with a rate of change greater than a certain value. For this reason, the neutron detector 10A ₁ ,
When a failure occurs in any one of 10A ₂ , 10B ₁ , and 10B ₂ , the signal from the averaging circuit 14B among the signals input to the comparator 26 is input to the rate of change limiter 3.
The rate of change is greater than that of the output signal of the averaging circuit 14A that is input through 0, and a difference occurs between the two. Therefore, when the difference becomes greater than a predetermined value, the comparator 26 switches the A/M station 22 to the manual mode.

In the above embodiment, the output signal of the averaging circuit 14A is inputted to the comparator 26 via the rate of change limiter 30. Press it to zero and output. A so-called delay element circuit may also be used.

〔Effect of the invention〕

As explained above, according to the present invention, the output signals of all the neutron detection means are input to each processing means,
The fluctuation of the output signal of one processing means is limited to a certain value or less, and a failure of the neutron detection means is detected from the deviation between the limited signal and the output signal of the other processing means. Therefore, it is possible to reliably and immediately detect a failure in the neutron detection means regardless of the situation, and it is possible to reliably prevent a fluctuation in the output of the nuclear reactor due to a failure in the neutron detection means.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional automatic reactor power control device, FIG. 2 is an explanatory diagram of an embodiment of the automatic reactor power control device that is the basis of the present invention, and FIG. 3 is an explanatory diagram of an embodiment of the automatic reactor power control device according to the present invention. It is an explanatory view of an example of an automatic control device. 10A ₁ , 10A ₂ , 10A _o , 10B ₁ , 10B ₂ ,
10B _o ...neutron detector, 14A, 14B...
Average circuit, 18... High value priority circuit, 20... Control rod drive control circuit, 22... A/M station,
24... Control rod drive device, 26... Comparator, 28
. . . Comparison device, 30 . . . Rate of change limiter.

Claims (1)

[Claims] 1. A plurality of neutron detection means for detecting the operating state of the reactor, and the detection signals of each neutron detection means are inputted into a plurality of systems, and the level of the input signals is averaged for each system. a plurality of processing means for processing; a control rod insertion signal output means for outputting a control rod insertion signal when the level of one of the output signals of each processing means exceeds a set value; A rate-of-change limiting means for limiting the rate of change in the level fluctuation of the output signal of one processing means to a certain value or less compares the output signal of the other processing means with the output signal of the rate-of-change limiting means, and determines the difference between the two. manual operation signal output means for outputting a manual operation signal when the value exceeds a set value;
An automatic reactor power control device comprising a control rod drive means that automatically inserts a control rod in response to a control rod insertion signal and responds to manual operation instead of automatic control rod insertion in response to a manual operation signal. 2. The automatic reactor output control device according to claim 1, wherein the change rate limiting means includes a delay element circuit that makes level fluctuations of the output signal of the processing means zero for a certain period of time.