JPS61241695A - Measuring device for neutron flux - 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 [Field of Application of the Invention] The present invention relates to a neutron flux measuring device for monitoring the thermal output of a nuclear reactor using neutron flux, and particularly to a neutron flux measuring device that can compensate for a decrease in sensitivity of a detector. .

[Background of the invention]

In a nuclear power generation system, a neutron flux measurement device that monitors the thermal output of a nuclear reactor using neutron flux is an important device related to a safety protection system that uses the measurement and calculation results of neutron flux to trip the plant. Numerous neutron flux detectors placed inside the reactor are used to monitor the output. Because the characteristics of these detectors vary among themselves and change over time, a method is used to correct these variations and changes over time by inserting a calibration detector into the reactor core. There is.

However, if we try to correct all neutron flux detectors, it will take a lot of time to calculate the sensitivity calibration constant for each neutron flux detector and readjust the sensitivity gain of the neutron flux measurement circuit based on the results of the calibration constant calculation. It was necessary. Therefore, it is desired to shorten the time required for these calibration operations, and many methods have been proposed. In addition, related devices for shortening the transit time in the reactor core of a detector for calibration and performing complicated calculations of sensitivity calibration constants using a computer include, for example, JP-A-56-79996 and JP-A-56-86398. The number is mentioned.

However, the above method requires humans to adjust the sensitivity gain of the neutron flux measurement circuit one by one based on the calculation result list of sensitivity calibration constants output by the process computer, which is time-consuming and extremely inefficient. It has become bad.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the conventional connection described above, to transmit the sensitivity calibration constants obtained by the calibration constant calculation device through an optical transmission line, and, after confirmation by an operator, to calculate the sensitivity calibration constants of the neutron flux measurement circuit. An object of the present invention is to provide a neutron flux measuring device for use in the present invention.

[Summary of the invention]

The present invention calculates a calibration value for each neutron flux detector based on the detection value of a calibration detector, and sends the calibration value through a line to perform calibration for each compatible detector. It is.

[Embodiments of the invention]

Hereinafter, the basic configuration of the neutron flux measuring device of the present invention will be explained with reference to FIG. This neutron flux measuring device includes m neutron flux detectors 11 (CH) for monitoring the thermal output inside the reactor pressure vessel 1 using neutron flux.

n neutron east measurement devices [8 (C
H, 1 to CH, n), the trip control circuit 9 which generates the trip signal for the control rod group 2, and the neutron flux detector 11 by taking 2/40th of the trip signal and the variation over time. , a calibration detector that travels inside the reactor core for calibration3. A calibration detector driving device 42 for running the calibration detector 3; a calibration detector signal conversion circuit 5 that converts the signal from the calibration detector 3 so that the calibration constant calculation device 6 can calculate the signal; and a calibration constant calculation device The sensitivity calibration constant calculated by 6 is applied to n neutron flux measuring devices 8 (CH
, 1 to CH, n).

7b. Note that the channel CH,1 does not mean one neutron flux detector, but refers to a plurality of neutron flux detectors. For example, CH,1 refers to a collection of 51 or 21 neutron flux detectors. Other CH, 2~C
The same applies to H and n.

FIG. 2 is a detailed example of the route from the reactor pressure vessel 1 to the calibration constant calculation device 6. Reactor pressure vessel 1
has a fuel assembly part IA, and in this fuel assembly part IA, a local power range monitor (LPRM) constituting the neutron flux detector 11 and a traveling neutron flux verification detector 3 (T
IP). The neutron flux detector s11 is provided at a fixed position within the reactor, and the calibration detector 3 is movable within the reactor and is utilized for calibrating the measured value by the neutron flux detector 11.

The calibration tube IB is a travel guide tube for the calibration detector 3. The indexer 4B is a means for selecting into which of the plurality of calibration tubes IB the calibration detector 3 is inserted. The drive unit 4C has a roll 4E, and a calibration detector 3 is attached to this roll 4E.
Wind up or unwind cable 4F. This controls the movement of the calibration detector l13 and selects the calibration tube IB.The roll 4E is the detector drive control circuit 4.
It is controlled by the drive command 4a of A. Also, the tip of the cable 4F of the calibration detector 3 is connected to the detector drive control circuit 4.
A and the output of detector 3 is taken in.

The neutron flux detectors 11 are arranged horizontally and vertically within the reactor, and measure a large number of local outputs. For example, 43 detector assemblies with built-in detectors 11 are used at four locations below the BWRM child power plant of approximately 1.1 million KW, making the total number of detectors 172. Because all of these neutron flux detectors have variations among each other and change over time, their outputs must be calibrated and used separately. Calibration is performed by a calibration detector 3 that moves within a calibration tube provided in each assembly of neutron flux detectors 11.

FIG. 3 is a diagram showing the arrangement of the fuel assembly IA and each detector. Inside the neutron flux detector housing 11A, there is a calibration tube I.
B and a plurality of neutron flux detectors 11 are housed therein.

Now, during calibration, the calibration constants differ for each neutron flux detector 11, and it takes a very long time to calibrate the outputs of all the neutron flux detectors.

An embodiment of the present invention in which this calibration is automatically performed is shown in FIG. FIG. 5 shows the processing flow.

FIG. 6 further shows a part of the flow.

In FIG. 4, a calibration constant calculation device 6 receives a calibration constant calculation signal a from a calibration detector signal conversion circuit 5, and performs calibration based on data calculated from the signal a and other necessary heat output of the furnace. Sensitivity calibration constant A of the detector
seek. Calibration constant calculation device! Reference numeral 6 outputs the data obtained by adding data B for identifying the detector to be calibrated and the corresponding sensitivity calibration constant A to the sensitivity calibration constant C, and outputs it to the optical transmission line 7a. The above processing is repeated in the flowchart of FIG.

The optical interface circuit 8a of the transmission control circuit 83 of each neutron measurement device 8 once takes in the data C and writes it into the memory 8C of the transmission control circuit 83. Using the detector identification data B, the processor 8b detects the detector to be calibrated. but,
It is determined whether this channel is connected to the neutral electric flux measuring device 8. If connected, the signal C is sent via the transmission control circuit dedicated bus 8j to the buffer circuit 80 which has separate interfaces for both the buses 8j and 8k of the transmission control circuit 83 and the measurement dedicated circuit 84. If it is not connected, the data C is output as is to the optical transmission line 7a again. Similarly, for the next channel, determine whether the detector to be calibrated is connected to your channel, and if it is not connected, take in that data C, and if it is not connected, send it to the next channel. Repeat this operation in sequence until you find the detector you want to calibrate. The above processing is designated as Y in FIG.

On the other hand, the data B written in the buffer circuit 80 is sent to the display control circuit 8g via the measurement-only circuit bus 8k under the management of the processor 8h of the measurement-only circuit 84, including the detector identification number and sensitivity. Calibration constants are displayed on display 82. The above processing is designated as Z in FIG. The operator checks the detector identification number and the sensitivity calibration constant, determines whether it is normal or abnormal based on past history of the sensitivity calibration constant, etc., and if there is no abnormality, gives a calibration permission signal using the confirmation operation switch 81. In response to the calibration permission signal taken in by the digital input circuit 8e, the processor 8h first writes data B of the buffer circuit 80 into the measurement-only circuit memory 81 via the measurement-only circuit bus 8k.

Based on the detector identification number and the sensitivity calibration constant written in the measurement-dedicated circuit memory 81, the processor 8h: □Performs sensitivity calibration of the corresponding detector.

Next, a transmission method when one channel of the neutron measuring device 8 fails will be explained with reference to FIG.

For example, if channel k of the neutron measurement device 8 fails, the neutron flux calibration calculation device 6 sends signals in two directions. One signal passes through the optical transmission line 7a and is transmitted to CH,1.
→CH, 24CH, transmitted to -1, channel -
-1→ to CH, via the optical transmission line 7b.
CH, 2 → CH, 1 → Neutron East calibration calculation device l! Reply to 6.

In addition, another signal is sent via the optical transmission line 7a to the C
H, n-4CH, n-1-+CH, transmitted to +1,
+1 to the channel and via the optical transmission line 7b,
CH, +1 → CH, +2 → CH, n-1 → CH, n
→It is sent back to the neutron east calibration calculation device 6.

FIG. 8 shows the basic configuration of another embodiment of the present invention. In this embodiment, the optical transmission line 7 connecting the neutron flux calculation device 6 and the neutron flux calibration device 8 is connected from the neutron flux calculation device 6 in a star shape. One neutron flux calibration device 8 is connected to one of the optical transmission lines 7 emitted from the neutron flux, and if the neutron flux calculation device breaks down, if only that channel is disconnected in terms of signal, there will be no effect on other channels. There is an advantage that there is no

According to this embodiment, the neutron flux measurement device that compensates for the decrease in sensitivity of the detector is electrically isolated from the calibration constant calculation device and the optical transmission line, and the transmission control circuit and the neutron flux measurement circuit are The calibration constant calculation device has a buffer circuit for exchanging data, and requires confirmation by an operator to use the sensitivity calibration for calculations in the neutral electric flux measurement circuit.

Calculation errors or failures in the optical transmission line or transmission control circuit do not affect the calculations of the neutron flux measurement circuit, so the neutron flux measurement circuit will not perform calculations with incorrect data, so there is no possibility of erroneous calibration. Moreover, since the sensitivity calibration constant of the calibration constant calculation device can be used directly for calculation of the neutron flux measurement circuit, it is possible to prevent erroneous calibration and reduce the calibration time.

〔Effect of the invention〕

According to the present invention, automatic calibration has become possible for each channel.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a detailed diagram of a part thereof,
Fig. 3 is a diagram showing an example of the interior of the reactor pressure vessel, Fig. 4 is a diagram of another embodiment of the present invention, Figs. 5 and 6 are processing diagrams thereof, and Figs. 7 and 8 are diagrams of the present invention. It is another Example 1 figure. 1... Reactor pressure vessel, 3... Calibration detector, 4...
... Calibration pressure detector drive device, 5... Calibration detector signal conversion circuit, 6... Calibration constant calculation device, 83... Transmission control circuit, 84... Measurement dedicated circuit.

Claims (1)

[Claims] 1. A plurality of neutron flux detectors provided within the reactor pressure vessel, a calibration detector movable within the reactor pressure vessel, and a detection value from the calibration detector. A first means for calculating a calibration value corresponding to a detector, and distributing the calculated calibration value to each detector, calibrating the detection value of each neutron flux detector, and calculating a nuclear reactor based on the calibrated detection value. A neutron flux measuring device comprising: second means for determining neutron flux within a pressure vessel. 2. The neutron flux measuring device according to claim 1, wherein the distribution by the second means is performed as data via a transmission line.