JPH068899B2 - Neutron flux measurement device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a neutron flux measuring device for monitoring the thermal output of a nuclear reactor by means of neutron flux, and more particularly to a neutron flux measuring device that is capable of compensating for sensitivity deterioration of a detector. .

[Background of the Invention]

In a nuclear power generation system, a neutron flux measuring device that monitors the thermal output of a nuclear reactor with a neutron flux is an important device related to a safety protection system that causes a plant trip based on the measurement and calculation results of the neutron flux. A large number of neutron flux detectors are used in the reactor to monitor the output of the reactor. Since the characteristics of these detectors vary from one another and change over time, a method of inserting a detector for calibration into the core and compensating for these variations and changes over time has been used. There is.

However, when trying to correct all neutron flux detectors, it takes a lot of time to calculate sensitivity calibration constants for each neutron flux detector and readjust the sensitivity gain of the neutron flux measurement circuit based on the calculation result of the calibration constants. I needed it. Therefore, it is desired to shorten the time for these calibration operations, and many methods have been proposed. Note that, as a device related to a device for shortening the core running time of a calibration detector and performing a complicated calculation of a sensitivity calibration constant by a computer, for example, Japanese Patent Laid-Open Nos. 56-79996 and 56-86398 are disclosed. No.

However, in the above method, since the human was adjusting the sensitivity gain of the neutron flux measurement circuit one by one based on the calculation result list of the sensitivity calibration constants output by the process computer, it took time and work efficiency was increased. It is extremely bad.

[Object of the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to transmit a sensitivity calibration constant obtained by a calibration constant computing device by an optical transmission line, and after confirmation by an operator, calculation of a neutron flux measurement circuit. It is to provide a neutron flux measuring device for use in.

[Outline of Invention]

The above-mentioned object is a plurality of neutron flux detectors provided in the reactor pressure vessel, a calibration detector movable in the reactor vessel, and the neutron flux detector from the detection value of the calibration detector. Computation means for computing calibration value data for each, and a neutron flux measuring device for measuring the neutron flux by the calibration value data for each neutron flux detector of the computing means and the detection value of each neutron flux detector In the neutron flux measurement device, while using an optical transmission line as a signal line for connecting the calculation means and the neutron flux measurement device and transmitting the calibration value data, the calibration value data transmitted through the optical transmission line When there is a storage confirmation operation, the calibration value data is output to the neutron flux measuring device and calibrated by a buffer means, a display means for displaying the calibration value data stored in the buffer means, and the display means. school By providing the instruction input means of the checking operation of the value data is achieved.

In the present invention, by using an optical transmission line as a signal line, electrical insulation is achieved, the influence of noise is reduced, and sensitivity is reduced. Further, since the buffer means, the display means and the instruction input means are provided and the calibration is performed after the operator determines whether the calibration value data is normal or abnormal, the calibration is prevented from being erroneously performed.

Example of Invention

The basic configuration of the neutron flux measuring apparatus of the present invention will be described below with reference to FIG. This neutron flux measuring device includes m neutron flux detectors 11 (CH.1 to CH.m) for monitoring the heat output in the reactor pressure vessel 1 by neutron flux, and signals from the neutron flux detector 11. To perform various calculations and output an alarm or trip signal when there is an abnormality n
A neutron flux measuring device 8 (CH.1 to CH.n), a trip control circuit 9 for generating a trip signal of the control rod group 2 by taking a 2/4 logic of the trip signal, and a neutron flux detector 11 Calibration detectors that travel in the core to calibrate variations and changes with time 3, calibration detector drive unit 4 that drives them, and signals from calibration detectors 3 to calculate calibration constants The calibration detector signal conversion circuit 5 for converting a signal so that the device 6 can calculate, and the sensitivity calibration constants calculated by the calibration constant calculation device 6 are n neutron flux measuring devices 8 (CH.1 to CH.n). ) Is comprised of optical transmission lines 7a and 7b having a double loop. In addition, the channel CH. 1 does not mean one neutron flux detector, but refers to a plurality of neutron flux detectors. For example, CH. 1 is a set of 51 or 21 neutron flux detectors. Other CH. 2 to CH. The same applies to n.

FIG. 2 is a detailed example of the path from the reactor pressure vessel 1 to the calibration constant calculation device 6. Reactor pressure vessel 1
Has a fuel assembly section 1A, and within this fuel assembly section 1A, a local output range monitor (LPRM) constituting a neutron flux detector 11 and a traveling type neutron flux detection detector 3 (TI
P). The neutron flux detector 11 is provided at a fixed position in the furnace, and the calibration detector 3 is allowed to travel in the furnace and is used for calibrating the measurement value by the neutron flux detector 11.

The calibration tube 1B is a travel guide tube for the calibration detector 3. The indexer 4B is a selection unit to which of the plurality of calibration tubes 1B the calibration detector 3 is inserted. The drive unit 4C is
The roll 4E is held, and the cable 4F of the calibration detector 3 is wound or unwound on the roll 4E. Thereby, the movement of the calibration detector 3 is controlled and the calibration tube 1B is selected. The roll 4E is controlled by the drive command 4a from the detector drive control circuit 4A. The tip of the cable 4F of the calibration detector 3 is guided to the detector drive control circuit 4A to capture the output of the detector 3.

The neutron flux detector 11 is arranged in a horizontal direction and a vertical direction in the reactor and measures a large number of local outputs. For example, in a BWR nuclear power plant of about 1.1 million KW, 43 detector assemblies having the detectors 11 built-in at four vertical positions are used, and the total number of detectors becomes 172. Due to variations in these neutron flux detectors and changes over time, their outputs must be calibrated separately before use. The calibration is performed by the calibration detector 3 that moves in the calibration tube provided in the assembly of the neutron flux detectors 11.

FIG. 3 is a diagram showing the arrangement of the fuel assembly 1A and the detectors. In the neutron flux detector housing 11A, the calibration tube 1
B and a plurality of neutron flux detectors 11 are housed.

Now, in the calibration, the calibration constants are different 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 signal a from the calibration detector signal conversion circuit 5 is taken in and a calibration constant calculation device 6
Calculates the sensitivity calibration constant A of the detector to be calibrated from the signal a and other data calculated by the core heat output and the like. The calibration constant calculation device 6 newly adds the data B for identifying the detector to be calibrated and the sensitivity calibration constant A corresponding thereto to the sensitivity calibration constant C again.
And output to the optical transmission line 7a. The above process is designated as X in the flow of FIG.

The optical interface circuit 8a of the transmission control circuit 83 of each neutron measuring device 8 once captures the data C and writes it in the memory 8C of the transmission control circuit 83. The processor 8b detects the data to be calibrated by the detector identification data B Container
It is determined whether or not it is connected to the neutron flux measuring device 8 of this channel. When connected, the signal C is sent via the transmission control circuit dedicated bus 8j to the buffer circuit 80 which has the interfaces separately on both the buses 8j and 8k of the transmission control circuit 83 and the measurement dedicated circuit 84. If not connected, the data C is directly output to the optical transmission line 7a again. Similarly, the next channel judges whether the detector to be calibrated is connected to its own channel, and if it is connected, acquires its data C, and if it is not connected, sends it to the next channel. Repeat this operation until the detector to be calibrated is found. The above process is designated as Y in FIG.

On the other hand, the data B written in the buffer circuit 80 is controlled by the processor 8h of the measurement dedicated circuit 84, passes through the measurement dedicated circuit dedicated bus 8k, and is displayed by the display control circuit 8g by the detector identification number and the sensitivity. The calibration constant is displayed on the display 82. The above process is designated as Z in FIG. The operator confirms the detector identification number and the sensitivity calibration constant, judges normality or abnormality from past history of sensitivity calibration constants, etc., and if there is no abnormality, the confirmation operation switch 81 gives a calibration permission signal. For the first time, the processor 8h writes the data B of the buffer circuit 80 to the measurement dedicated circuit memory 8i via the measurement dedicated circuit dedicated bus 8k by the calibration permission signal fetched by the digital input circuit 8e.

The processor 8h calibrates the sensitivity of the corresponding detector based on the detector identification number and the sensitivity calibration constant written in the dedicated measurement circuit memory 8i.

Next, a transmission method in the case where one channel of the neutron measuring device 8 fails will be described with reference to FIG.

For example, when the channel k of the neutron measuring device 8 fails, the neutron flux calibration computing device 6 sends signals in two directions. One signal passes through the optical transmission line 7a, CH. 1
→ CH. 2 → CH. transmitted to k-1 and channel k-
1 via the loopback optical transmission line 7b, CH. k-1 →
CH. 2 → CH. 1 → Reply to the neutron flux calibration computing device 6.

Further, another signal is transmitted via the optical transmission line 7a to C
H. n → CH. n-1 → CH. It is transmitted to the k + 1 channel, and at the channel k + 1 via the return optical transmission line 7b, C
H. k + 1 → CH. k + 2 → CH. n-1 → CH. n →
It is returned to the neutron flux calibration arithmetic unit 6.

FIG. 8 shows the basic structure of another embodiment of the present invention. In this embodiment, one neutron is provided for each optical transmission line 7 that connects the neutron flux calculation device 6 and the neutron flux measurement (calibration) device 8 to the star-shaped optical transmission line 7 emitted from the neutron flux calculation device 6. The flux measurement (calibration) device 8 is connected, and when the neutron flux calculation device fails, there is a merit that if the channel is disconnected, the other channels are not affected at all.

According to the present embodiment, the neutron flux measuring device that compensates for the decrease in the sensitivity of the detector is electrically insulated by the calibration constant calculation device and the optical transmission line, and further, the transmission control circuit and the neutron flux measuring device. It has a buffer circuit for exchanging data, and requires a confirmation operation by the operator in order to use sensitivity calibration for calculation in the neutron flux measurement circuit. Therefore, a calibration constant calculation device, optical transmission line, transmission control circuit The calculation error or failure of
Since it does not affect the operation of the neutron flux measurement circuit,
Since the neutron flux measurement circuit does not operate with incorrect data, it is possible to prevent incorrect calibration.
Furthermore, since the sensitivity calibration constant of the calibration constant calculation device can be directly used for the calculation of the neutron flux measurement circuit, there are effects of preventing erroneous calibration and reducing the calibration time.

〔The invention's effect〕

According to the present invention, since the optical transmission line is used as the signal line, the influence of electrical noise is small and the sensitivity is not significantly reduced. In addition, since the buffer means, the display means, and the instruction input means are provided and the calibration is performed only after the operator judges whether the calibration value data is normal or abnormal, the error is caused by a failure in the computing means or the optical transmission line. The risk of calibration with the calibration value data is avoided, and safety is enhanced.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a partial detailed view thereof,
FIG. 3 is a view showing an example of the inside of a reactor pressure vessel, FIG. 4 is another embodiment of the present invention, FIGS. 5 and 6 are processing diagrams thereof, and FIGS. 7 and 8 show the present invention. It is another example figure of. DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 3 ... Calibration detector, 4 ... Calibration detector driving device, 5 ... Calibration detector signal conversion circuit, 6 ... Calibration constant calculator, 83 ... Transmission control circuit, 84 ... Measurement only circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Matsumiya 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Co., Ltd. Omika Factory (72) Inventor Kazuhiko Ishii 5-chome, Omika-cho, Hitachi City, Ibaraki Prefecture 2-1 Incorporated company Hitachi, Ltd. Omika factory (72) Inventor Kenichi Matsuda 3-2-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Engineering Co., Ltd. (56) Reference JP-A-51-41200 ( JP, A)

Claims (1)

[Claims] 1. A plurality of neutron flux detectors provided in a reactor pressure vessel, a calibration detector movable in the reactor vessel, and the neutron flux detection based on detection values of the calibration detector. Computation means for computing the calibration value data for each instrument, and a neutron flux measuring device for measuring the neutron flux by the calibration value data for each neutron flux detector of the computation means and the detection value of each neutron flux detector In a neutron flux measuring device comprising, while using an optical transmission line as a signal line for connecting the calculation means and the neutron flux measuring device and transmitting the calibration value data, the calibration value data transmitted through the optical transmission line The buffer means for outputting the calibration value data to the neutron flux measuring device for calibration when there is a storage confirmation operation, a display means for displaying the calibration value data stored in the buffer means, and a display means for displaying the calibration value data. School Neutron flux measuring apparatus characterized by comprising an instruction input means of the checking operation of the value data.