JP4334124B2 - Reactor digital power range monitoring system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reactor power region monitoring system, and more particularly to a reactor digital power region monitoring system that monitors reactor power fluctuations and generates an alarm when an abnormality occurs.
[0002]
[Prior art]
Light water reactors include boiling water reactors (BWR, ABWR) and pressurized water reactors (PWR). These reactors monitor reactor power fluctuations and output warnings when abnormal An area monitoring system is provided.
[0003]
In a conventional reactor power region monitoring system, a plurality of local power region monitor detector assemblies (hereinafter referred to as LPRM detector assemblies) are provided in the reactor core. The LPRM detector assembly includes four local power region monitor detectors (hereinafter referred to as LPRM detectors) and a mobile in-core instrumentation system detector (hereinafter referred to as TIP detectors) housed in LPRM strings. . In the LPRM detector assembly, four LPRM detectors are arranged independently in the vertical direction of the core, and a channel is configured for each LPRM detector.
[0004]
In the conventional reactor power region monitoring system, the neutron flux in the reactor core is measured by each LPRM detector, and the reactor average power and local power are measured and monitored. Is generated, the control rod is prevented from being pulled out, and a control rod full insertion signal (scram signal) is generated. The reactor power region monitoring system is required to have high reliability and quick response in order to output an output signal that drives the safety system of the reactor.
[0005]
As described above, the reactor power region monitoring system is required to have high reliability and soundness, and when an abnormality occurs in the reactor, a shortening of the recovery time and a function of preventing erroneous operation by a human operation system are required. The power range monitor system is connected to a number of LPRM detectors in the reactor.
[0006]
The LPRM detector is a fission detector capable of detecting a neutron flux, and is mounted in the reactor about 80 to 200. The LPRM detector needs to be periodically calibrated because the detection sensitivity deteriorates with the passage of time of use. There is a TIP detector as a calibration detector for the LPRM detector, and this TIP detector is inserted into the TIP guide tube of LPRM strings by the operation of a mobile in-core instrumentation system (hereinafter referred to as TIP system) during calibration. It can be moved up and down in the core. Based on the signal information from the TIP detector, gain correction (calibration) is performed for each LPRM detector.
[0007]
However, a TIP system having a TIP detector for calibrating LPRM detectors requires a large and large drive mechanism to move the TIP detectors up and down in the core for each gain correction of each LPRM detector. . In addition, the TIP system needs to be installed in the reactor building. However, since the operation for gain correction becomes complicated in addition to the increase in size, it takes a long time for gain correction, which is a problem. In order to easily and easily perform the gain correction operation of each LPRM detector, it is desired to realize a system such as a simple man-machine interface.
[0008]
FIG. 15 is a principle diagram showing the arrangement relationship between the current reactor power region monitoring system and the TIP system.
[0009]
A plurality of, for example, 43 LPRM detector assemblies 3 are arranged in the core 2 of the nuclear reactor 1. Each LPRM detector assembly 3 accommodates four LPRM detectors 5 and a TIP guide tube 6 which are independent in an LPRM string 4. Each LPRM detector 5 is connected to an output area monitor system 8 via a signal cable 7.
[0010]
The output area monitor system 8 includes an average output area monitor (hereinafter referred to as APRM) 9 and a data transmission unit (hereinafter referred to as DCF) 10. The APRM 9 averages the output signals from the grouped LPRM detectors 5, and the output information from the APRM 9 is transmitted to the process control computer 11 via the DCF 10. The process control computer 11 is provided in an external computer building different from the reactor building 12, and based on the output information from the APRM 9, a data log function for recording various data in the nuclear power plant, and reactor operation monitoring・ Has a function to perform performance calculations.
[0011]
In addition, the TIP detector 13 accommodated in the TIP guide tube 6 is accommodated in such a manner that the TIP guide tube 6 in the reactor core is selected by the driving of the large TIP system 14 and is movable in the vertical direction of the core.
[0012]
The TIP system 14 includes a mechanical drive device such as a detector drive device 15 that moves the TIP detector 12, a traction device 16 that selects the TIP guide tube 6, a valve mechanism 17, and a shut-off container 18. While the TIP system 14 has a complicated structure and increases in size, dynamic operations such as a movement operation and selective engagement operation of the TIP detector 12 become complicated. In addition, since the TIP detector 12 is taken in and out of the reactor core and activated, the dynamic operation of the TIP detector 12 needs to be performed carefully and safely in consideration of radiation exposure prevention. Cost.
[0013]
On the other hand, the detector signal value from the TIP detector 12 obtained by the TIP system 14 is sent to the process control computer 11 via the TIP neutron flux signal processing device 19. The process control computer 11 is also sent the LPRM detector signal value obtained by the output region monitor system 8, and the process control computer 11 performs correction calculation for sensitivity deterioration of the LPRM detector 5. The sensitivity deterioration is corrected by adjusting the gain value for each detector signal (neutron flux signal) from each LPRM detector 5.
[0014]
By the way, recently, the progress of digitization technology is remarkable, and the output area monitor system 7 is also designed to incorporate the digitization technology. An example of the digital output area monitor system 8 is shown in FIG.
[0015]
The digital output area monitor system 8 shown in FIG. 16 is a system composed of a plurality of units, for example, six APRM units 9A to 9F, two DCF units 10A and 10B, and two controls. It consists of rod pull-out monitoring units 20A and 20B.
[0016]
The core 2 of the nuclear reactor 1 is loaded with, for example, a 102-channel LPRM detector 5, and a neutron flux (LPRM) signal from each LPRM detector 5 is sent to the corresponding APRM units 9A to 9F. In the APRM units 9A to 9F, they are converted into digital signals which are A / D converters (not shown), averaged, sent to the process control computer 11 via the DCF units 10A and 10B, and subjected to arithmetic processing to generate reactor output and the like. Desired.
[0017]
On the other hand, since each LPRM detector 5 has a deterioration in neutron detection sensitivity, a correction calculation for sensitivity deterioration is performed. The sensitivity correction of each LPRM detector 5 is performed by adjusting the gain value. This gain adjustment (correction) is based on the gain correction information from the process control computer 11, and the human operating system performs each LPRM detector 5 for each channel, or via the DCF units 10A and 10B. The gain of each LPRM detector 5 is corrected by downloading to the APRM units 9A and 9B constituting the safety system.
[0018]
[Problems to be solved by the invention]
The TIP system 14 used for correcting the sensitivity deterioration of the LPRM detector 5 is a large and large-scale system. In order to obtain the LPRM calibration signal information in the conventional TIP system 14, a complicated operation is required, which takes time and labor. It was. For this reason, the gain correction (calibration) of each LPRM detector 5 performed in the output region monitor system is performed for each periodic inspection, and sensitivity degradation diagnosis and degradation prediction diagnosis of each LPRM detector are performed in a normal operation state. I couldn't.
[0019]
Further, the gain correction (calibration) of each LPRM detector is performed based on the correction calculation performed by the process control computer 11, and each time the gain correction is performed, the gain correction information from the process control computer 11 is used as an APRM constituting the safety system. The units are downloaded to the units 9A to 9F, and the gain value is corrected by a human operation system.
[0020]
However, unlike the APRM 9, the process control computer 11 does not constitute a constantly operating safety system, and is a device having a low reliability and safety level unlike the safety system. Moreover, since the plant control computer 11 is installed in a computer building outside the reactor building and performs gain correction of each LPRM detector 5 based on feedback information (gain correction information) from the process control computer 11, a gain correction system is provided. Therefore, it is difficult to perform gain correction with high reliability and stably and accurately.
[0021]
Furthermore, the digital output area monitor system that monitors the output of the reactor 1 and issues an alarm when an abnormality occurs has a display / operation unit for each APRM unit 9A to 9F. Operations such as status display and setting value setting are performed. Since the display / operation unit is distributed for each APRM unit, the number of parts is large, and the operation of each display / operation unit must be performed in a distributed manner. Was bad and was a problem.
[0022]
The present invention has been made in consideration of the above-described circumstances. The maintenance diagnosis processing system of the LPRM detector is simplified and simplified, the reliability and safety of the maintenance diagnosis apparatus of the LPRM detector is improved, and the diagnosis function is provided. It is an object of the present invention to provide an improved digital power range monitoring system for a nuclear reactor.
[0023]
Another object of the present invention is to perform LPRM gain correction in a safety loop with a high reliability and safety level, improve the maintenance diagnosis function of the LPRM detector, and improve safety and reliability. It is an object of the present invention to provide an improved digital power range monitoring system for nuclear reactors.
[0024]
Still another object of the present invention is to stably and accurately change and adjust the internal set value of the LPRM detector, improve operability, simplify maintenance work such as regular inspection, and reduce work time. An object of the present invention is to provide a digital power range monitoring system for a nuclear reactor that can be greatly shortened.
[0027]
[Means for Solving the Problems]
In order to solve the above-described problems, a digital power range monitoring system for a nuclear reactor according to the present invention includes a plurality of LPRM detectors installed in the core of a nuclear reactor as described in claim 1, and each LPRM. By measuring the neutron flux measured by the detector, the reactor average output and local output are measured and monitored, and in the output region monitor system that issues an alarm in the event of an abnormality, the γ thermometer is housed together with the LPRM detector A plurality of in-core nuclear instrumentation assemblies are installed in the reactor core, and a γ thermo system that captures sensor information from the γ thermometer is connected to an average output area monitor (APRM). This APRM is connected to the gamma thermo system. Comparison / difference processing system that compares the sensor information of the sensor and the signal information from the LPRM detector to determine the difference between the two signal values, and monitors the difference between the two signal values It is obtained by a detector degradation diagnostic processing system for determining the sensitivity degradation of the LPRM detector Te.
[0028]
In order to solve the above-described problem, the digital output region monitoring system for a nuclear reactor according to the present invention is characterized in that, as described in claim 2, the APRM is configured to process LPRM signal information for processing signal information from the LPRM. A processing system, and a feedback circuit that feeds back the gain correction information from the detector deterioration diagnosis processing system to the LPRM signal information processing system, and the LPRM signal information processing system includes an LPRM detector of the detector deterioration diagnosis processing system. The gain correction information associated with the sensitivity deterioration is input and the LPRM detector is set to perform gain correction. Further, as described in claim 3, the γ thermometer is provided in the in-core nuclear instrumentation assembly. A plurality of γ-ray heat detectors are installed in the core axis direction corresponding to each LPRM detector, while γ-ray emission near the LPRM detector to be judged is set. APRM has a γ thermosensor information processing system that captures sensor information from the detector, and the γ thermosensor information processing system predicts the local core output at the LPRM detector position to be determined from the sensor information, and performs this prediction. The local core output is used as a comparison reference value for sensitivity degradation of the LPRM detector to be determined.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a digital output region monitoring system for a nuclear reactor according to the present invention will be described with reference to the accompanying drawings.
[0033]
FIG. 1 shows an embodiment of a digital power range monitoring system for a nuclear reactor according to the present invention. This digital power range monitoring system is designed to measure and monitor the average power and local power of the reactor, and to generate an alarm in the event of an abnormality, and is applied to boiling water reactors, pressurized water reactors, etc. be able to. FIG. 1 shows an example in which the digital output region monitor system 21 is applied to a boiling water reactor 22.
[0034]
The nuclear reactor 22 is stored in a nuclear reactor containment vessel 24 stored in a nuclear reactor building 23. The core portion 25 of the nuclear reactor 22 is provided with a plurality of in-core nuclear instrumentation assemblies 26. FIG. 1 shows an example in which only one body is displayed.
[0035]
As shown in FIGS. 1 and 2, the in-core nuclear instrumentation assembly 26 includes a local output region monitor system (LPRM) 28 as a neutron detector assembly and a γ exothermic detector assembly in a nuclear instrumentation tube 27. The thermometer 29 is combined and fixedly arranged integrally, and is arranged in the core portion 25 of the nuclear reactor 22 at an appropriate interval in the vertical direction.
[0036]
The LPRM 28 has, for example, four LPRM detectors 30 that are fixed neutron detectors at an equal interval in the axial direction, and the γ thermometer 29 has N, for example, 7 to 9 γ Line detectors 31 are provided discretely in the axial direction. Each LPRM detector 30 and the γ-ray heat detector 31 are accommodated in a nuclear instrumentation tube 27 constituting an LPRM string.
[0037]
The neutron flux signal (LPRM signal) detected by each LPRM detector 30 is input to the digital output region monitor system 21 through the signal cable 33. An output region monitor system 21 receives and digitizes an LPRM signal, which is an analog signal, and calculates an average power region monitor (APRM) 34 for calculating an average power of the reactor core, and an APRM signal connected to the APRM 34 is a process control computer. The data transmission unit (DCF) 36 to be transmitted to 35 and all the LPRM detection signals in the reactor 21 are received from the APRM 34, and the LPRM detection signals around the control rods are monitored when the control rods (not shown) are pulled out. A control rod pull-out monitoring device (hereinafter referred to as RBM) 37 and a display / operation panel 38 for performing operations such as display of monitoring data / alarm status and setting of set values.
[0038]
On the other hand, the γ-ray heat generation detection signal (sensor signal) detected by each γ heat generation detector 31 of the γ thermometer 29 is input to the process control computer 35 via the sensor cable 40 as a signal processed by the γ thermo system 41. On the other hand, it is input to the APRM 34 of the output area monitor system 21. The γ thermo system 41 includes a measurement control unit 42 and a heater heating heat source 43.
[0039]
The γ thermo system 41 is a system that can detect the neutron distribution in the reactor core by measuring the γ ray calorific value due to radiation absorption by the γ thermometer 29 that is a fixed sensor, and a calibration signal source that does not require a driving mechanism. Used as Since the γ thermo system 41 detects the amount of γ ray heat generated by each γ ray heat detector 31, it is difficult to cope with fast core power fluctuations, but a fixed sensor resident in the reactor core. Therefore, unlike the TIP system shown in FIG. 15, the core power distribution can be obtained at all times. Further, unlike the LPRM detector 30, the γ thermometer 29 has a characteristic that hardly deteriorates measurement sensitivity.
[0040]
Further, the digital output area monitor system 21 is actually divided into two systems of A system 21A and B system 21B as shown in FIG. 3, and is a system composed of a plurality of units.
[0041]
The digital type output area monitor system 21 is usually eight, in the illustrated example, six APRM units 34A to 34F, two DCF units 36A and 36B, two control rod pull-out monitoring units 37A and 37B, 2 The display / operation panel 38A, 38B.
[0042]
An 80 to 200 channel (ch) LPRM detector 30 is mounted on the core 25 of the nuclear reactor 22. FIG. 3 shows an example provided with a 102 ch LPRM detector 30. Each LPRM detector 30 is connected to one APRM unit 34A to 34F, for example, for 17 channels, and is subjected to signal processing, and the LPRM signal processed by each APRM unit 34A to 34F is averaged. . The APRM signal is output to the process control computer 35 via the DCF units 36A and 36B.
[0043]
The output area monitor system 21 also displays RBM units 37A and 37B that monitor LPRM detection signal values around the control rods during monitoring rod pull-out operations and monitoring data / alarm status outside the APRM units 34A to 34F. And display / operation panels 38A and 38B for setting the set values. The display / operation panels 38A and 38B are provided for each of the A-system and B-system output area monitoring systems 21A and 21B, and are operated in a centralized manner by the integrated display / operation panels 38A and 38B. The visibility and operability of the output area monitor system 21 can be improved.
[0044]
FIG. 4 is a block diagram showing the signal processing of the APRM 34 provided in the digital output area monitor system 21.
[0045]
The APRM 34 captures sensor information from the γ thermo system 41 for each unit 34A to 34F by a transmission means such as an electrically insulated MI cable, and processes the γ thermo sensor information processing system 45 from the LPRM detector 30. The LPRM signal information processing system 46 that captures and processes the signal information, compares both of these pieces of information, compares and determines the difference amount, and the difference processing system 47, and performs deterioration diagnosis of the LPRM detector from the processed difference amount. And a detector deterioration diagnosis processing system 48.
[0046]
The γ thermo sensor information processing system 45 is adapted to incorporate sensor information from the γ thermo system 41 periodically or as required by the APRM 34 side. Γ thermo reception processing circuit 50 is received. The reception processing circuit 50 receives the signal in a rated output state where the output state of the reactor 21 is stable. The determination of whether or not the reactor 21 is stable is made by confirming that the core average power measured by the APRM 34 is within a predetermined fluctuation range within a certain time.
[0047]
The γ thermo reception processing circuit 50 includes an A / D converter 51 that converts an analog signal into a digital signal and a signal amplifier 52 that amplifies the converted signal. The γ thermosensor signal processed and digitized by the reception processing circuit 50 is input to the interpolation processing circuit 54 via the storage area storage circuit 53.
[0048]
The interpolation processing circuit 54 pays attention to the fact that the LPRM detector 30 and the γ-ray heat detector 31 have different height positions in the core axis direction, and as shown in FIG. 2, the LPRM detector 30A to be determined (calibrated). In consideration of the position in the axial direction of the reactor core, the Newton method or the like is known based on sensor information (γ ray heat generation amount) from a plurality of γ ray heat detectors 31 that are physically arranged around the LPRM detector 30. The output value calculated by the calculation method is used as an output value to be determined (corrected). The correction reference output value corresponding to the LPRM detector 30A to be determined is obtained from the relationship between the reactor power and the core radial direction (X axis) position shown in FIG. 2 and the relationship between the core axis direction (Z axis) position and the reactor output. be able to.
[0049]
In the LPRM signal information processing system 46, the LPRM signal from the LPRM detector 30 is received by the LPRM reception processing circuit 56. The LPRM reception processing circuit 56 includes an A / D converter 57 that converts the received LPRM signal from an analog signal to a digital signal, and a signal amplifier 58 that amplifies the converted LPRM signal.
[0050]
The LPRM signal processed by the LPRM reception processing circuit 56 is converted into a value corresponding to the reactor output and the thermosensor signal by the conversion processing circuit 59 and sent to the circuit 60 of the comparison determination and difference processing system 47.
[0051]
The comparison determination and difference processing circuit 60 compares the processed γ thermosensor signal with the LPRM processing signal, obtains a difference between both signals, and monitors the difference amount (difference information). The difference information processed by the difference processing circuit 60 is input to the diagnosis processing circuit 61 of the LPRM detector deterioration diagnosis processing system 48, where the state of sensitivity deterioration of the LPRM detector 30 including the presence / absence of the difference information is analyzed. I have a diagnosis.
[0052]
Further, the difference information between the γ thermosensor signal and the LPRM signal compared by the comparison determination and difference processing circuit 60 is stored in the storage memory 62 and accumulated. The past difference information stored in the storage memory 62 is sent to the diagnosis processing circuit 61, where the difference value is monitored by the diagnosis processing circuit 61, and when there is a fluctuation more than a predetermined difference value, An alarm is output from the alarm generation circuit 63.
[0053]
Further, the difference information obtained by the comparison determination and difference processing circuit 60 and the past difference information stored in the storage memory 62 are sent to the display means 64 via the diagnosis processing circuit 61, and are requested by the operator as shown in FIG. It can be displayed as shown in (A) and (B).
[0054]
By the way, since the sensitivity degradation rate of the LPRM detector 30 is faster than the γ-ray heat detector 31 which is a sensor of the γ thermo system 41, the sensor information (curve a) from the γ thermo system 41 as the usage time elapses. And the difference information ΔS between the signal information from the LPRM detector 30 (curve b) tends to increase as shown in FIG. Therefore, a sensitivity deterioration curve c indicated by a solid line in FIG. 5B is obtained from the difference amount ΔS shown in FIG. 5A, and the sensitivity deterioration indicated by a broken line is obtained from the deterioration curve of the sensitivity deterioration curve c and the current time PT. An expected curve d is calculated. A time exceeding the allowable deterioration range e corresponding to the alarm set value is predicted in advance from the sensitivity deterioration prediction curve d, and the operator is notified. These processes are performed by the LPRM detector deterioration diagnosis processing system 48. The deterioration diagnosis processing system 48 includes at least a diagnosis processing circuit 61 and a storage memory 62.
[0055]
By performing deterioration diagnosis of the LPRM detector 30 in the units 34A to 34F of the APRM 34 used for calculating the average value, it is possible to perform LPRM detector deterioration diagnosis in a safety loop with high reliability and safety level. In addition, when the soundness of the LPRM detector 30 is confirmed and an abnormality is detected, an operation for excluding from the average calculation can be performed immediately, and highly reliable calculation information can be output, so that maintainability can be improved.
[0056]
The gain information of the LPRM detector 30 processed by the diagnostic processing circuit 61 is connected to the reception processing circuit 56 of the LPRM signal information processing system 46 via the feedback circuit 65, and the diagnostic processing circuit 61 is connected to the LPRM reception processing circuit 56. The change information (corresponding to the gain change information) determined from the difference information processed in the above is fed back, and the gain adjustment (correction) of the LPRM detector 30 is performed.
[0057]
By providing the feedback circuit 65, the gain correction (calibration) processing of the LPRM detector 30 can be performed in the loop of the units 34A to 34F of the APRM 34. The feedback of gain correction information from the process control computer 35 becomes unnecessary, and the gain adjustment (gain calibration) of the LPRM detector 30 is performed in the loop of the APRM 34 constituting the safety system having a high reliability and safety level. Simplified, highly functional and reliable.
[0058]
As shown in FIGS. 1 and 4, by directly connecting the γ thermo system 41 to the APRM 34, gain correction (calibration) calculation of the LPRM detector 30 that has been performed by an external process control computer 35 that does not conventionally constitute a safety system. The feedback circuit 65 can be provided in the APRM 34 to perform all the operations in the safety loop.
[0059]
The gain correction (calibration) calculation of the LPRM detector 30 is performed individually for each channel of the LPRM detector 30 when a sensitivity degradation alarm is generated by an alarm generation signal from the alarm generation circuit 63 or periodically. The The gain correction of the LPRM detector 30 is performed by correcting the sensitivity deterioration by a feedback operation of gain information from the diagnosis processing circuit 61 on the basis of the value of the γ ray heat generation amount from the γ thermometer 29. The gain information from the diagnosis processing circuit 61 is change information determined from the comparison determination and the output difference information of the difference processing circuit 60. The feedback information 65 is obtained by using this change information as a gain alarm, and is sent to the LPRM reception processing circuit 56. The gain is adjusted by feedback.
[0060]
When the gain correction operation (change operation) of the LPRM detector 30 occurs, the gain change (calibration) content is notified to the external process control computer 35 and the display of the display / operation panel 38.
[0061]
In the digital output area monitor system 21, as shown in FIGS. 4 and 5, the fluctuation of the difference information is monitored by the diagnostic processing circuit 61 and the display means 64, and the alarm set value E in which the difference amount ΔS is set in advance. When the value is reached, an alarm signal is output from the alarm generation circuit 63 as a set value abnormality.
[0062]
Further, as shown in FIG. 5B, a sensitivity deterioration prediction curve d is created from the sensitivity deterioration curve c displaying the difference ΔS and the current time PT, and the prediction curve d and the alarm set value e are used. The alarm generation time FT is predicted and the display means 64 is operated so that the operator can be notified.
[0063]
In the digital output area monitor system 21, the difference information of all the LPRM detectors 30 can be arbitrarily determined periodically or as required by the units 34A to 34F of the APRM 34. In particular, when there is an area of the LPRM detector 30 having a large sensitivity deterioration, the LPRM detector 30 having a large sensitivity deterioration to be determined can be easily specialized and discriminated, and information necessary for the operation of the nuclear power plant can be efficiently obtained. Well, can be provided in a timely manner.
[0064]
At that time, gain correction (calibration) processing of the LPRM detector 30 is performed as shown in FIG. 6 as an example. The difference amount (difference value) when the LPRM detector 30A to be calibrated (determined) (see FIG. 2) is relatively unused is used as data A, and the sensitivity degradation of the LPRM detector 30A occurs and approaches the calibration time. When the difference amount (difference value) at this time is data B, correction processing is performed by multiplying the gain value of the LPRM detector 30A to be calibrated by B / A.
[0065]
The gain correction processing of the LPRM detector 30 may be performed by taking in another parameter (external factor) X from the outside and performing additional processing, and various gain correction processing can be considered. In particular, when the γ-ray heat generation detector 31 of the γ thermometer 29 corresponding to the LPRM detector 30A to be calibrated is damaged and lost, γ-ray heat generation information from a plurality of γ-ray heat generation detectors 31 in the vicinity thereof. Complement processing is performed by the APRM 34 using (sensor information). For example, when a specific γ-ray heat generation detector 31 is missing, the sensor information of the γ-ray heat generation detector 31 above and below (up and down adjacent to the core axis direction) and γ in the horizontal direction (direction adjacent to the core radial direction). The gain calibration (correction) of the LPRM detector 30 may be performed as a gain calibration reference value with reference to the sensor information of the line heat detector 31.
[0066]
In this digital output area monitor system 21, the gain correction (calibration) of the LPRM detector 30A to be calibrated can be performed by the APRM 34 itself without the aid of the process control computer 35 or the like. And confirmation work, transmission operation in the external signal processing system such as the process control computer 35 can be omitted, the signal processing system for gain calibration of the LPRM detector 30 can be simplified and simplified, Since the APRM 34 can be configured, maintainability and reliability can be improved.
[0067]
In one embodiment of the digital output area monitor system 21, the gain calibration process of the LPRM detector 30 is performed by the units 37 A and 37 B or the DCF unit 36 A of the control rod pull-out monitoring device (RBM) 37 in the output area monitor system 21. You may enable it to implement within 36B.
[0068]
Since the RBM units 37A and 37B or the DCF units 36A and 36B are connected to all the APRM units 34A to 34F as shown in FIG. 3, the LPRM signal information from all the LPRM detectors 30 in the reactor core. By comparing and discriminating the acquired signal with the sensor signal from the γ thermo system 41, the gain correction calculation of all the LPRM detectors 30 can be performed, and gain correction (calibration) is possible. Become. In this case, the sensor information from the γ thermo system 41 is input to the units 37A and 37B or the DCF units 36A and 36B of the RBM 37.
[0069]
The DCF unit 36 or the RBM 37 is less responsive to the device than the APRM 34 and has a relatively long processing time for the computing unit, so that it is easy to perform gain correction processing. In this case, the units 34A to 34F of the APRM 34 and the units 37A and 37B of the RBM 37 or the units 36A and 36B of the DCF 36 are isolated transmission processing systems capable of bidirectional signal transmission as shown in FIG. Connected with.
[0070]
Next, the structure and measurement example of the γ thermometer 29 will be described.
[0071]
FIG. 1 shows an example in which the γ thermometer 29 includes, for example, seven γ-ray heat detectors 31 as fixed sensor units. The γ thermometer 29 is an elongated rod-like assembly having a diameter of about 8 mmφ, for example, and has a length that substantially covers the entire effective fuel length in the core axis direction. Since the γ thermometer 29 does not need to move the sensor portion that is the γ-ray heat detector 31, unlike the TIP system, the γ thermometer 29 does not require a sensor driving device, and the γ thermosystem 41 can be reduced in size and size.
[0072]
An example in which the γ thermometer 29 includes, for example, nine γ-ray heat detectors 31 is shown in FIGS. Of the γ-ray heat detectors, four are in the same axial position as the LPRM detector 30, three are in the middle of each LPRM detector 30, and the remaining two are from the upper or lower LPRM detector 30. You may make it provide in each upward or downward.
[0073]
The structure of the γ thermometer 29 is shown in FIG. In the γ thermometer 29, a metal long rod-shaped core tube 69 is accommodated in a cover tube 68 formed of, for example, stainless steel as a metal jacket, and the cover tube 68 is caulked to the core tube 69 and shrink-fitted or cooled. It is fixed with a fit. Between the cover tube 68 and the core tube 69, a sleeve-like or annular gap portion 70 constituting a heat insulating portion is formed, and a plurality of, for example, seven to seven, the annular gap portions 70 are spaced apart in the axial direction. Nine are arranged discretely. The annular gap 70 is formed by cutting out the outer surface of the core tube 69 along the circumferential direction, and a gas having low heat conduction, for example, Ar gas, is enclosed in the annular gap 70. The annular gap 70 may be formed on the cover tube 68 side which is a jacket tube.
[0074]
Further, a γ-ray heat detector 31 is provided at the position where the annular gap 70 is formed as shown in FIG. 8 and constitutes each sensor portion of the γ thermometer 29. The core tube 69 has an internal hole 71 penetrating in the axial direction at the center, and a cable sensor assembly 72 formed into an MI cable is fixed to the internal hole 71 by brazing or caulking.
[0075]
The cable sensor assembly 72 includes a built-in heater 73 as a calibration rod-shaped heating element of the γ thermometer 29 and a differential thermocouple (thermocouple) 74 as a plurality of temperature sensors at the center. The built-in heater 73 and each thermocouple 74 are hardened with an electrical insulating layer or a metal / metal alloy filler 75 and are integrally accommodated in the metal cladding tube 76, and the metal cladding tube 76 is in close contact with the outer surface and the inner surface. The built-in heater 73 is formed of, for example, a sheathed heater, and the heater wire 77 is covered with a metal cladding tube 79 via an electrical insulating layer 78 and integrated. Similarly, each thermocouple 74 is also integrally formed by covering a thermocouple wire 80 with a metal cladding tube 82 via an electric insulating layer 81.
[0076]
The differential thermocouples 74 disposed in the inner hole 71 of the core tube 69 are respectively disposed corresponding to the annular gaps 70 and constitute the γ-ray heat detector 31. As shown in FIG. 8, each thermocouple 74 has a high temperature side contact 85 a at the center in the axial direction of the sensor portion, that is, the heat insulating portion formed by the annular gap 70, and a low temperature side contact 85 b at a lower position slightly away from the heat insulating portion. (The low temperature side contact 85b may be at an upper position slightly away from the heat insulating portion). The thermocouples 74 are inserted concentrically around the built-in heater 73 by the number of the γ-ray heat detectors 31.
[0077]
The γ thermometer 29 is an in-furnace output distribution detector (γ-ray heat detector) assembly, and the in-furnace output distribution measurement principle is shown in FIGS. 9 (A) and 9 (B).
[0078]
In a nuclear reactor 22 such as a boiling water reactor, γ rays are generated in proportion to the nuclear fission amount of nuclear fuel loaded in the reactor core 25, and the structure of the γ thermometer 29 such as a core tube is generated by the generated γ ray bundle. 69 is heated. This amount of heating is proportional to the gamma ray flux, and the gamma ray flux is proportional to the amount of fission in the vicinity.
[0079]
In the annular gap portion 70 of each γ-ray heat detector 31 that is a sensor portion of the γ thermometer 29, heat removal by the radial coolant 86 is poor due to its heat insulation, so an axis as indicated by an arrow A A heat flux detouring in the direction is generated, resulting in a temperature difference. Therefore, if the high temperature side contact 85a and the low temperature side contact 85b of the differential thermocouple 74 are arranged as shown in FIG. 8, this temperature difference can be detected by a voltage signal. Since this temperature difference is proportional to the γ-ray heating value, the γ-ray heating value proportional to the local fission amount can be obtained from the voltage signal of the differential thermocouple 74. This is the measurement principle of the γ thermometer 29.
[0080]
Next, a second embodiment of the digital output region monitoring system for a nuclear reactor according to the present invention will be described.
[0081]
FIG. 10 simply shows another example of a digital power region monitoring system for a nuclear reactor. The power region monitoring system 21 is separated into two systems, an A system and a B system, and is shown in FIG. As shown, the APRM 34 is divided into, for example, six units 34A to 34F.
[0082]
The units 34A to 34F are roughly divided into three units, and output area monitor systems 21A and 21B of the A-system and B-system APRMs are configured. The other configuration of the digital output area monitor system 21 is not different from that shown in FIGS.
[0083]
Each APRM unit 34A to 34F does not have a display / operation unit inside the unit, and has a display / operation panel 38 independent of each APRM unit 34A to 34F outside the unit. The display / operation panel 38 includes common display / operation panels 38A, 38B for each of the A-system APRM units 34A, 34C, 34E and for each of the B-system APRM units 34B, 34D, 34E.
[0084]
The digital output area monitor system 21 is stored in the A-system and B-system output area monitor panel 90. FIG. 10B shows an A-system output area monitor panel 90 having a box shape. The A-system APRM units 34A, 34C, 34E are stored in the A-system output area monitor panel 90, and the LPRM signals are averaged by the APRM units 34A, 34C, 34E. Operations such as display of monitoring data and alarm status and set values of the APRM units 34A, 34C, 34F are performed on a common display / operation panel 38A.
[0085]
The display / operation panel 38A is configured so that an operator can operate each of the A-system APRM units 34A, 34C, 34E, and is incorporated in the front panel 91 of the A-system output area monitor panel 90, and has a common man-machine interface. It is composed.
[0086]
Each APRM unit 34A, 34C, 34E constituting the A-system output area monitor panel 90 is provided with a confirmation button 92 and a power lamp 93 constituting unit confirmation means for each unit. The confirmation button 92 of each APRM unit 34A, 34C, 34E is connected to a display / operation panel 38A constituting a common man-machine interface, and the display / operation panel 38A displays a display linked to the confirmation button 92. When the link with the confirmation button 92 cannot be confirmed, the unit information of the APRM units 34A, 34C, 34E cannot be displayed on the display / operation panel 38A.
[0087]
The operation of the A-system output area monitor panel 90 is performed by the operator operating the operation unit 95 of the display / operation panel 38A. Selection of the APRM units 34A, 34C, 34E to be operated is performed in advance. For example, a confirmation button 92 that is a unit confirmation unit of the APRM unit 34E that is a determination target to be performed is pressed. By pressing the confirmation button 92 of the determination (operation) target APRM unit 34E, the power lamp 93 is turned on, and the unit information of the determination target APRM unit 334E is displayed on the display unit 96 of the display / operation panel 38A. Unit information of only the target APRM unit 34E is confirmed by a common man-machine interface.
[0088]
As described above, when the unit information of the APRM unit 34E to be determined is displayed or operated on the display / operation panel 38A, the confirmation operation of the operator is performed by the unit confirmation means 92. Therefore, the APRM units 34A, 34C, It is possible to reliably and effectively prevent the erroneous operation of 34E.
[0089]
The output area monitor system 21 divides the APRM 34 into a plurality of units, and collects and displays a common display / operation panel 38A outside the APRM units 34A, 34C, 34E, and is linked to the display / operation panel 38A. The unit confirming operation of each APRM unit by the unit confirming unit 92 is set so as to be the display / operation start condition of the display / operation panel 38A.
[0090]
FIG. 11 shows a flowchart of the confirmation / change operation of each APRM unit 34A, 34C, 34E of the A-system output area monitor panel 90. The same applies to the B system output area monitor panel.
[0091]
The operation involving the mode change of the APRM units 34A, 34C, 34E, that is, the operation for changing the setting value in the unit, etc., has a limit on the number of units that can be changed at one time. Even if is entered, it is set to be ignored.
[0092]
It is generally undesirable in design that the display function of the display / operation panel 38 </ b> A affects the internal operation on the device side with a high safety rank due to the request on the device side with a low safety rank. However, in the A system output area monitor panel 90 shown in FIG. 10 (B), the confirmation buttons 92 are respectively installed in the APRM units 34A, 34C, 34E constituting the safety system having a high safety rank and reliability. By using the confirmation button 92 attached to the APRM units 34, 34C, 34E, it is possible to secure an operation process for performing the display / change operation of the display / operation panel 38A in response to a request from the APRM unit having a high safety rank. When man-machine interfaces having a display function are integrated, the safety of the entire output area monitor system 21 can be improved.
[0093]
The display / operation panel 38A constituting the man-machine interface is integrated and shared, and the confirmation operation on the APRM unit 34 side is performed with the shared display / operation panel 38A, and then the operation can be performed intensively. And visibility can be improved. In addition, since it is not necessary to provide the display / operation unit 38 in each APRM unit 34A, 34C, 34E, the number of parts can be reduced.
[0094]
In the example shown in FIG. 10, the display / operation panel 38A is provided in the digital output area monitor system 21. However, the display / operation panel 38A connects each unit of the APRM 34 via a network. Alternatively, it may be configured so that it can be operated remotely, and display and operation can be performed from a remote location. The display / operation panel 38A may display and operate not only the A-system APRM units 34A, 34C and 34E but also the B-system APRM units 34B, 34D and 34F in the same manner.
[0095]
FIG. 12 shows a third embodiment of the digital output region monitoring system for a nuclear reactor according to the present invention.
[0096]
This embodiment shows an example of an A-system output area monitor panel 90 constituting the digital output area monitor system 21. Since the B system output area monitor panel is not different from the A system output area monitor panel 90, its description is omitted. The other configuration of the digital output area monitor system 21 is not substantially different from that shown in FIGS.
[0097]
The A-system output area monitor panel 90 shown in FIG. 12 stores the three units 34A, 34C, and 34E of the APRM 34, and includes a display / operation panel 38A that constitutes a common man-machine interface. The display / operation panel 38A is connected to each of the A-system APRM units 34A, 34C, 34E, respectively, and each APRM unit 34A, 34C, 34E is provided with a key 98 with a key as unit lock means so as to be detachable.
[0098]
The internal setting value changing operation of each APRM unit 34A, 34C, 34E is an operation linked to the keyed key 98, and the internal setting value changing operation cannot be performed unless the keyed key 98 is turned ON.
[0099]
The keyed key 98 is interlocked with an interlocking switch 99 as shown in FIG. The non-volatile memory 100 is turned on and off by the interlock switch 99. The non-volatile memory 100 maintains the memory function even when the power is turned off by the OFF of the interlock switch 99. Hard connected.
[0100]
In the digital output area monitoring system 21, when changing the internal set value information of each APRM unit 34, a key with key 98 as a unit lock means for permitting the internal set value change for each APRM unit 34A, 34C, 34E. The internal setting value of the APRM unit cannot be changed unless it can be changed and set by operating the keyed key 98. To change the internal set value, first, the keyed key 98 is operated to select a specific unit among the A-system APRM units 34A, 34B, 34E, and then the operation unit 95 of the display / operation panel 38A is operated. It is done by doing.
[0101]
Among the APRM units 34A, 34C, 34E, it is not possible to change the setting of a plurality of units simultaneously. In a state where a plurality of APRM units can be set at the same time, an erroneous operation of the APRM unit 34 is reliably and beforehand prevented as a system configuration in which the internal setting value cannot be changed.
[0102]
In this digital output area monitor system 21, the APRM 34 is divided into a plurality of units 34A, 34C, 34E, and a common display / operation panel 38A is provided outside the APRM units 34A, 34C, 34E. Unit lock means 98 linked to the operation panel 38A is provided for each of the APRM units 34A, 34C, 34E, and the unlocking operation by the unit lock means 98 changes the APRM unit internal set value information to be determined by the display / operation panel 38A. This is set to be a start condition.
[0103]
In the digital output area monitor system 21 shown in FIGS. 12 and 13, the display / operation panel 38A connected to each A-system APRM unit 34A, 34C, 34E constitutes a common man-machine interface. Yes. Even if an APRM unit for which the key with key 98 is not turned ON by mistake is issued with the display / operation panel 38A to change the setting of the internal setting value, the internal setting value of the APRM unit other than the judgment (operation) target It is possible to reliably prevent change requests and improve safety.
[0104]
FIG. 14 is a flowchart for changing the internal setting value of the APRM unit to be changed (determination), for example, 34E, of the APRM 34 provided in the digital output area monitor system 21. Also in this case, the internal setting value change request of the APRM unit 34E to be determined constitutes a safety system, and the setting value changing work is performed by a request from the APRM unit 34E side having a high safety rank. A highly safe digital output area monitor system 21 can be provided.
[0105]
When the internal setting value of the APRM unit is changed by the digital output area monitor system 21, since it is performed by operating the key 98 with the key from the APRM unit side having a high safety and reliability level, the display / operation functions are integrated. Even if a common man-machine interface is used, the setting change operation is performed while the operator is surely confirming which unit the APRM unit 34E currently displayed corresponds to. Can be prevented. In order to prevent this erroneous operation and to ensure soundness, colors and characters (symbols) may be different for each APRM unit as a display method displayed on the display unit 96.
[0106]
【The invention's effect】
As described above, the digital output region monitoring system for a nuclear reactor according to the present invention performs processing independently in a safety APRM loop having a high reliability and safety level, and from outside a process control computer or the like. This eliminates the need for this process, simplifying the maintenance diagnosis processing system of the LPRM detector, enabling highly reliable gain correction processing in a short time, and ensuring the reliability and safety of the maintenance diagnosis function of the LPRM detector. It is possible to improve the performance and improve the functionality.
[0107]
In addition, the digital output region monitoring system for a nuclear reactor according to the present invention can change and adjust (gain correction) the internal set value of the LPRM detector stably and accurately in the loop of the safety system. It is possible to improve the performance, simplify the maintenance work at the time of regular inspection, and greatly shorten the work time.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a digital output region monitoring system for a nuclear reactor according to the present invention.
FIG. 2 shows a reactor core side of a digital output region monitoring system for a nuclear reactor according to the present invention, and is a schematic diagram of an in-core nuclear instrumentation assembly loaded in the reactor core, and an in-core nuclear meter The figure which shows the relationship between the reactor power measured with a loading assembly, a core axial direction position, and a core radial direction position.
FIG. 3 is a system diagram showing a system configuration example of a digital output region monitoring system for a nuclear reactor according to the present invention.
4 is a diagram showing a system configuration example in which a γ thermo system is introduced into the digital output region monitoring system of the nuclear reactor shown in FIG. 3;
FIG. 5A is a graph showing a detection sensitivity deterioration state of the LPRM detector, and FIG. 5B is a graph that enables deterioration prediction from the detection sensitivity deterioration state of the LPRM detector.
FIG. 6 is a diagram showing a calculation example in which gain correction calculation is performed by APRM provided in the digital output region monitoring system for a nuclear reactor according to the present invention.
FIG. 7 is a cross-sectional view of a fixed γ thermometer provided in the digital output region monitoring system for a nuclear reactor according to the present invention.
8 is a partial schematic cross-sectional view showing an example of the structure of the fixed γ thermometer shown in FIG. 7;
FIG. 9A is a diagram showing an arrangement example of an in-core nuclear instrumentation assembly of a nuclear reactor provided in a digital output region monitoring system for a nuclear reactor according to the present invention, and FIG. An explanatory view showing a principle of measuring γ ray heat generation of a fixed type γ thermometer provided in an instrumentation assembly and a temperature distribution diagram of γ ray heat generation.
FIG. 10A shows a second embodiment of a digital output region monitoring system for a nuclear reactor according to the present invention. FIG. 10B is a simplified schematic diagram of the output region monitoring system, and FIG. The figure which shows the output area monitor board provided with the system.
FIG. 11 is a flowchart showing a flow of changing an internal setting value through a common display / operation panel (man machine interface).
FIG. 12 is a diagram showing a power region monitor panel according to a third embodiment of the digital power region monitor system for a nuclear reactor according to the present invention.
13 is a diagram showing a circuit example including an interlocking switch interlocking with unit lock means provided in the output area monitor panel shown in FIG. 12;
FIG. 14 is a flowchart showing a flow of changing an internal setting value by a common display / operation panel (man machine interface).
FIG. 15 is a system diagram showing a conventional power region monitoring system of a nuclear reactor.
FIG. 16 is a diagram showing a system configuration example of a system of a conventional digital output region monitoring system for a nuclear reactor.
[Explanation of symbols]
21 Output area monitor system
22 Reactor
23 Reactor building
24 Primary containment vessel
25 Core
26 In-core nuclear instrumentation assembly
27 Nuclear instrumentation tube (LPRM string)
28 Local output region monitor system (LPRM)
29 γ thermometer
30 LPRM detector
31 γ-ray heat detector
33 Signal cable
34 Average output area monitor (APRM)
34A-34F APRM unit
35 Process control computer
36 Data transmission unit (DCF)
36A, 36B DCF unit
37 Control rod withdrawal monitoring device (RBM)
37A, 37B RBM unit
38, 38A, 38B Display / Operation Panel
40 Sensor cable (MI cable)
41 γ thermo system
42 Measurement control unit
43 Heat source for heater heating
45 γ Thermosensor Information Processing System
46 LPRM signal information processing system
47 Comparison judgment and difference processing system
48 Detector deterioration diagnosis processing system
50 γ Thermo reception processing circuit
51 A / D converter
52 Signal amplifier
53 Storage area storage circuit
54 Interpolation processing circuit
56 LPRM reception processing circuit
57 A / D converter
58 Signal amplifier
59 Conversion circuit
60 Comparison determination and difference processing circuit
61 Diagnostic processing circuit
62 Memory
63 Alarm generation circuit
64 display means
65 Feedback circuit
68 Guide tube
69 core tube
70 Cavity
71 Internal hole
72 Cable sensor assembly
73 Built-in heater
74 Differential Thermocouple (Thermocouple)
76 Metal cladding tube
77 Heater wire
78 Electrical insulation layer
79 Metal cladding tube
80 Thermocouple wire
81 Electrical insulation layer
82 Metal cladding tube
83 Coolant
90 Output area monitor panel
91 Front panel
92 Confirmation button (unit confirmation means)
93 Power lamp
95 Operation unit
96 display
98 Key with key (unit lock means)
99 Interlocking switch
100 Nonvolatile memory
101 Calculator

Claims (3)

By installing multiple LPRM detectors in the reactor core and measuring the neutron flux measured by each LPRM detector, the reactor average power and local power are measured and monitored, and an alarm is issued when an abnormality occurs In the output area monitor system,
A plurality of in-core nuclear instrumentation assemblies containing γ thermometers together with the LPRM detector are installed in the reactor core, and a γ thermo system for capturing sensor information from the γ thermometer is used as an average output area monitor (APRM). Connected, this APRM compares the sensor information from the gamma thermo system and the signal information from the LPRM detector to obtain the difference amount between the two signal values, and monitors the difference amount between the two signal values. And a detector deterioration diagnosis processing system for discriminating sensitivity deterioration of the LPRM detector, and a digital output region monitoring system for a nuclear reactor.   The APRM includes an LPRM signal information processing system that processes signal information from the LPRM, and a feedback circuit that feeds back the gain correction information from the detector deterioration diagnosis processing system to the LPRM signal information processing system, and the LPRM signal information 2. The digital output region of a nuclear reactor according to claim 1, wherein the processing system is set to perform gain correction of the LPRM detector by inputting gain correction information accompanying sensitivity deterioration of the LPRM detector from the detector deterioration diagnosis processing system. Monitor system.   The γ thermometer has a plurality of γ-ray heat detectors installed in the reactor core instrumentation assembly corresponding to each LPRM detector in the core axis direction, while a γ-ray heat detector near the LPRM detector to be determined. APRM is provided with a γ thermosensor information processing system that captures sensor information from the sensor, and the γ thermosensor information processing system predicts the local core output at the LPRM detector position to be determined from the sensor information, and the predicted local core 2. The digital output region monitoring system for a nuclear reactor according to claim 1, wherein the output is used as a comparison reference value for sensitivity deterioration of the LPRM detector to be judged.

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