JPS6235636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a neutron measurement device that monitors neutron flux, and more particularly to a neutron measurement device that automatically adjusts the gain of an amplifier in an output system neutron monitor.

In a boiling water reactor, n (for example, 100 to 200) in-core neutron detectors 1 are installed in the reactor core to measure the neutron flux (thermal output) distribution in the reactor core, as shown in Figure 1. -1, 1-2, ..., 1-n are installed to detect the neutron flux at each point, and send the detection signal to each amplifier 3-1, 3-2, ... 3-n of the output system neutron monitor 2. It is supplied to and amplified. The output signals of the amplifiers 3-1, 3-2, ... 3-n are supplied to a process computer 5 (hereinafter referred to as a process computer) via an isolator 4.
Similarly, the signal is supplied to the full-core display section 6 via the isolator 4. This isolator 4 outputs
A safety system such as the system neutron monitor 2 and a non-safety system such as the program controller 5 are separated to prevent a failure on the program controller 5 side from interfering with the output system neutron monitor 2. The program controller 5 performs core performance calculations based on the neutron flux input via the isolator 4.

In addition, in the case of the power system neutron monitor 2, the recirculation flow rate of the reactor detected by the flow rate detector 7 is converted into a signal by the flow rate conversion circuit 8 as appropriate, and the signal is converted by the flow rate conversion circuit 8.
-2, .

By the way, generally the in-reactor neutron detector 1-1, 1
-2, ..., 1-n uses something like a fission-type ionization chamber coated with nuclear fission such as natural uranium or boron, so the above substances burn over time by irradiation with neutrons. self-destruction occurs, resulting in a gradual decrease in detection sensitivity. Also,
Since the in-core neutron detectors 1-1, 1-2, . . . , 1-n locally detect neutrons in the reactor core, their detection sensitivities vary. However, since the power system neutron monitor 2 monitors the entire system, individual in-core neutron detectors 1-1, 1-2,..., 1-n
In order to eliminate unevenness in detection sensitivity, it is necessary to adjust the gains of the individual amplifiers 3-1, 3-2, . . . , 3-n inside the monitor.

Conventionally, these amplifiers 3-1, 3-2,..., 3-
The gain adjustment of n is performed manually. Therefore, due to the manual operation, careful attention and perseverance are required.

In addition, when the control rods are operated, the neutron flux distribution in the reactor changes, so the APRM coefficient, or peaking coefficient (average value of the neutron flux in the reactor is multiplied by the coefficient of the neutron flux distribution, is calculated to calculate the actual neutron flux). Corresponding coefficients) need to be changed, and in this case, the same operations as those for lowering the detection sensitivity of in-core neutron detection 1-1, 1-2, . . . , 1-n are required.

By the way, in the reactor core performance calculation, the neutron detection sensitivity is corrected every day by the program controller 5, and the peaking coefficient is also corrected whenever the reactor pattern is changed.

However, on the output system neutron monitor 2 side,
As mentioned above, the amplifiers 3-1, 3-2,..., 3-
Not only does it take time to set the gain of n, but also the scrum monitoring function is stopped during this time. However, the output system neutron monitor 2, which has a scram function, originally belongs to a safety system that requires high reliability, and needs to be separated from other non-safety systems such as the program controller 5. However, the scram monitoring function of the output system neutron monitor 2 cannot be lost. It is also not allowed to output an error trip. For this reason, the amplifier 3 by the procon 5
-1, 3-2, . . . , 3-n gain automatic setting is not performed. However, in practice, the amplifier 3-1,
There is an inconvenience that the scram monitoring function must be stopped when setting the gains of amplifiers 3-2,..., 3-n.
There was an urgent need to set the gains of 1, 3-2, . . . , 3-n.

The present invention has been made in view of the above-mentioned circumstances, and allows manual and automatic adjustment of the amplifier gain of the power system neutron monitor, as well as automatic adjustment of the amplifier gain from the non-safety system program controller that calculates the reactor performance. To provide a neutron measurement device that enables the neutron measurement system to maintain the scram monitoring function and the function of the neutron flux measurement system by holding the gain adjustment value on the output system neutron monitor side in the event of a failure on the processing controller side. .

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a block diagram of the entire apparatus, and FIG. 3 is a specific example of the internal structure of the amplifier shown in FIG. 2. In Fig. 2, neutron detectors 11-1, 11-2,...,
11-n are individual amplifiers 13-1 and 13-n of the output system neutron monitor 12, which is placed at each point in the reactor core (not shown) and which detects the neutron flux at that point and belongs to the safety system.
2,..., 13-n. These amplifiers 13-1, 13-2, . . . , 13-n have a configuration example shown in FIG. 3, and a detailed explanation thereof will be given later.

On the other hand, the program controller 14 belonging to the non-safety system is separated from the output system neutron monitor 12 for nuclear safety reasons, but the output system neutron monitor 12 is electrically connected to the arithmetic control circuit 16 as a data output control means via an isolator 15. connected. The main purpose of this program controller 14 is to calculate core performance, but it also collects calibrated gain adjustment data and peaking coefficient data once a day.
It is serially transmitted to the degree calculation control circuit 16. The arithmetic control circuit 16 reads the data multiple times and determines that it is not due to noise etc. if the data is the same, and sends the gain adjustment data to the amplifiers 13-1 and 13-1.
13-2, . . . , 13-n simultaneously supply the peaking coefficients to the averaging circuit 17 cyclically as parallel data. 18, 19 and 20 are a flow rate detector, a flow rate conversion circuit 19 and a scram monitoring circuit having the same functions as 7, 8 and 10 in FIG.

By the way, the amplifiers 13-1, 13-2,
..., 13-n are digitally set with gain adjustment data from the arithmetic control circuit 16, and an example of their internal configuration is as shown in FIG. That is, this amplifier, for example 13-1, is switched to either automatic or manual switching mode, and this switching mode is determined by the arithmetic control circuit 16 based on data received from the processor 14. When automatically adjusting the gain, data for automatic gain adjustment is latched by a latch circuit 131 in response to a data read signal, and then supplied to a digital amplifier 132 for gain adjustment. When manually adjusting the gain, the amplifier itself outputs data for manual gain adjustment and the latch circuit 133
After latching, the signal is supplied to a digital amplifier 132 for gain adjustment. The neutron flux detected by a neutron detector, for example 11-1, enters the digital amplifier 132, and after adjusting the gain, sends it to the subsequent control circuit 21. This control circuit 21
has a multiplexer, serial data transmission and other necessary functions, converts neutron flux data into serial data, and connects isolators 22 and 23, respectively.
The signal is supplied to the processor 14 and the full-core display section 24 via.

Next, the operation of the neutron measuring device as described above will be explained. The neutron detector 11 is calibrated by the program controller 14, which calculates core performance using neutron flux data sent from the power system neutron monitor 12.
-1, 11-2,..., 11-n amplifier gain data and neutron detectors 11-1, 11-2,..., due to changes in the power distribution in the reactor due to control rod operations.
Neutron monitor 12 outputs peaking coefficient data (corrected neutron flux distribution) of 11-n about once a day.
The data is serially transmitted to the arithmetic control circuit 16 of the controller via the isolator 15. By transmitting data serially, the number of wires is significantly reduced, reducing plant instrumentation costs, improving data reliability, and facilitating handling in the event of a failure.

If the arithmetic control circuit 16 reads data multiple times from the processor 14 side, it determines whether the data are the same or not. If the data are the same, it confirms that the data is not due to noise or the like and confirms that the data is the same. If it does not occur multiple times, the gain adjustment setting value will be kept at the previous value and a transmission failure will be displayed. After determining the quality of the data in this way, the arithmetic control circuit 16 converts it into data for automatic gain adjustment and outputs the data to the amplifiers 13-1, 13-2,..., 13-n.
In addition, the peaking coefficient data is simultaneously supplied to the averaging circuit 17 cyclically as parallel data. By digitally setting data for automatic gain adjustment to the amplifiers 13-1, 13-2, . . . , 13-n at the same time, automatic gain adjustment can be performed even on-line. This gain automatic adjustment data is constantly cyclically used for amplifier 1.
By supplying the signal every 3-1, 13-2, . . . , 13-n, there is no need to re-set the automatic gain adjustment data by inserting or removing a printed circuit board during maintenance.

By the way, as mentioned above, the amplifiers 13-1, 13
-2,..., 13-n, when automatically adjusting the gains of the amplifier 1 shown in FIG.
3-1, 13-2, . . . , 13-n, the automatic switching mode is switched to the automatic side. Then, the automatic gain adjustment data is read using the data read signal and latched into the latch circuit 131. If the arithmetic control circuit 16 malfunctions for some reason, the self-diagnosis function of the circuit 16 sets it to manual switching mode.
The latch circuit 133 is set to the operating state via an operation selection circuit such as an inverter, thereby following the setting of the manual gain adjustment data. This setting is for example amplifiers 13-1, 13-2,..., 1
3-n should be able to do it by himself. Manual gain adjustment must be done every day using the data from the program controller 14, but if the furnace pattern etc. is not changed for about a week, the gain change will be small.
There is no need for such frequent gain adjustments. Even if you perform gain adjustment every day, this function is for backup in case of failure, so it is not necessary for online measurement.
There is no problem with this, and manual adjustment of the gain is easy.

On the other hand, when the processing controller 14 fails, the data for automatic gain adjustment is not sent, so the data is not changed, but the function of the output system neutron monitor 12 is not changed at all. In the automatic switching mode, the latch circuit 131 latches the automatic gain adjustment data and the amplifiers 13-1, 13-2, . . .
13-n, or the gain may be adjusted manually using the manual switching mode. Of course, in the event of a failure in the arithmetic control circuit 16, the amplifier 13-
Since the gains of 1, 13-2, . . . , 13 . In this way, depending on the automatic or manual switching mode, the data for automatic gain adjustment or the data for manual gain adjustment are respectively transferred to the latch circuit 13.
1,133, and the gain of the digital amplifier 132 is adjusted using that data.

Then, the digital amplifiers 132, .
The gain of the neutron fluxes supplied from 3-2, . . . , 13-n is adjusted and sent to the subsequent control circuit 21. This control circuit 21 includes a multiplexer and serial transmission means, and amplifiers 13-1, 13-2,
..., 13-n is converted into serial data and transmitted to the processor 14 via the isolator 22. The program controller 14 calculates the reactor core performance based on serially input neutron flux data, and further obtains the above-mentioned automatic gain adjustment data and peaking coefficient data. The reason why the transmission line for the neutron flux data is separate from that for the automatic gain adjustment data from the program controller 14 side is to prevent the neutron level monitoring function from being impaired.

It goes without saying that the present invention is not limited to the above embodiments. For example, the arithmetic control circuit 16 may have a hard logic configuration or may use a microcontroller. In addition, the amplifiers 13-1, 13-2, ..., 13-n may be configured as only the digital amplifier 132, and other functions may be incorporated into the arithmetic control circuit 16. In this case, the arithmetic control circuit 16 In addition to the original data output control means, it also has the other functions mentioned above.

As detailed above, according to the present invention, the amplifier gain data calibrated from the program controller that calculates the reactor core performance and the peaking coefficient data of the neutron detector associated with changes in the power distribution in the reactor due to control rod operations are collected. Since the configuration is such that the information is transmitted to the output system neutron monitor and the gain of the amplifier is automatically adjusted, it is possible to improve the inconvenience that requires special manual attention and perseverance, and at the same time, eliminate the situation where the scram monitoring function stops. The reliability can be improved by this. In addition, data for automatic gain adjustment and neutron flux data are serially transmitted in one direction, and are separated into safety and non-safety systems by isolators, so they are not affected by each other, and the processing controller side Even in the event of malfunction, it does not affect the neutron flux measurement function or the scram monitoring function, which is preferable from the standpoint of reactor safety regulations. The output system neutron monitor allows not only automatic gain adjustment but also manual adjustment, so it can be used as a backup, and online measurements can reliably transmit neutron flux data to the processing controller without any problems.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a block diagram showing an embodiment of the neutron measuring device according to the present invention, and FIG. 3 is a specific block diagram of the amplifier shown in FIG. 2. 11-1, 11-2,..., 11-n...neutron detector, 12...output system neutron monitor, 13-
1, 13-2,..., 13-n... amplifier, 14...
...Procomputer (process computer), 15...
...Isolator, 16... Arithmetic control unit, 17...
...Averaging circuit, 18...Flow rate detector, 20...Scrum monitoring circuit, 21...Control circuit, 22...Isolator, 131...Latch circuit, 132...Digital amplifier, 133...Latch circuit. 〓〓〓〓〓

Claims (1)

[Claims] 1. After amplifying the neutron flux data of a plurality of neutron detectors arranged at each point in the reactor core with respective amplifiers of the output system neutron monitor of the safety system, the output of these plurality of amplifiers is is averaged in an averaging circuit and used for scram monitoring, and is also used for calculating reactor core performance by a non-safety system computer via a first transmission line. to second
data transmission means for transmitting data for automatic gain adjustment of the amplifier and peaking coefficient data of the neutron detector via a transmission line; Based on the determination result, a switching mode signal, a data read timing signal, and automatic gain adjustment data are supplied to the plurality of amplifiers, and peaking coefficient data is supplied to the averaging circuit. a first latch circuit that receives the data read timing signal and captures and holds the automatic gain adjustment data;
a second latch circuit that holds manual gain adjustment data; an operation selection circuit that selectively operates the first and second latch circuits in response to the switching mode signal; and the first and second latch circuits. A neutron measuring device comprising: the amplifier whose gain is set according to the output data of the amplifier. 2. The neutron measuring device according to claim 1, wherein data exchange between the safety system output system neutron monitor and the non-safety system computer is serially transmitted via an isolator. 3. The neutron measuring device according to claim 1, wherein the data output control means sets the gains for the plurality of amplifiers only when the data from the computer is received the same number of times as desired. 4. The neutron measuring device according to claim 1, wherein the data output control means has a self-diagnosis function and outputs a manual switching mode signal in the event of an abnormality.