Nuclear plant diagnosis apparatus and method

Abstract: This invention concerns a plant diagnosis apparatus which comprises a first detecting unit (10) for detecting a state of devices constituting a circulating system (1) in which a fluid circulates and a second detecting unit (20, 22, 31) for detecting a quality of the above-mentioned circulating fluid or a quality of the atmosphere surrounding the above-mentioned circulating system (1), and a unit for diagnosing the circulating system (1) by output of the first and second detecting units, and therefore can diagnose anomaly of facilities such as a nuclear power plant with high reliability and rapidity.

Description: BACKGROUND OF THE INVENTION This invention relates to a plant diagnosis apparatus and method according to claims 1 and 11, respectively. Heretofore, technologies for anomaly diagnosis of equipment including a circulating system have been disclosed in JP-A-64-46694 and JP-A-59-60293. JP-A-64-46694 concerns a method in which a parameter under observation is measured, and from its output level, anomaly is diagnosed. In a region where a radioactive level is high such as a nuclear reactor primary system, this method depends very much upon the soundness of the measuring instrument. In the prior art is known a method in which large threshold values are set for outputs of process quantities in steady state, and when a process parameter exceeds its large threshold value, threshold values of other process parameters are lowered and diagnosis is conducted. JP-A-59-60293 relates to a circulating system and describes a method for diagnosing an anomaly from correlation between two parameters under observation (conductivity and pH) concerned with water quality. According to the above-mentioned prior art, when an anomaly occurs, a decision as to whether the anomaly is a true anomaly or an anomaly orginating in the detector caused by noise or the like cannot be made. Especially, when the detector can detect an anomaly only by a transient signal, it is impossible to confirm whether the anomaly is a true anomaly. Therefore, the problem with the prior art is that anomaly cannot be diagnosed with high reliability. The method described in JP-A-59-60293 can detect ions when they are produced by an anomaly of the equipment, but cannot detect particulate substances such as clad. SUMMARY OF THE INVENTION The object of the present invention is to provide a plant diagnosis apparatus and method featuring high reliability for use in a plant including a circulating system capable of detecting anomaly when particulate substances such as clad are produced. This object is achieved with the subject matter independent apparatus and method claims 1 and 11. The diagnostic principle of first and second embodiments are described below. When an anomaly occurs in some of the devices constituting the circulating system, a change occurs in the fluid itself flowing in the circulating system or a change occurs in the atmospheric environment around the circulating system. Therefore, when an anomaly occurs in the devices, the quality of the fluid or the atmosphere around the circulating system is detected, so that a reliable decision can be made whether an anomaly has actually occurred or not. The above-mentioned diagnostic principle will be described with reference to an example in which abnormal vibration occurs in the circulating system. A possible cause of the abnormal vibration is an anomaly in rotary devices such as pumps or the loosening of the fixed members such as pipes or the like. When abnormal vibrations occur in some devices, particulate substances such as clad initially adhering to the internal walls of the devices or to the structural members near the devices comes off and falls down caused by the vibration, or the device material is scrubbed off by friction, for example. As a result, in the former case, the number of particles of the particulate substances increases in the circulating water in the device. In the latter case, the scrubbed-off metal become ions, flowing in the fluid, so that the conductivity or the hydrogen-ion concentration (pH) changes. The basic patterns of change are shown in Figs. 2 and 3. Fig. 2 shows a case in which the vibration indicating the state of the devices, constituting the circulating system, changed with a conspicuous change in level and the number of particles of the particulate substances in the circulating fluid, which indicates the quality of the circulating fluid, changed substantially at the same time with a notable change in level. Fig. 3 presents a case in which the vibration occurred a sudden pulse-like, transient phenomenon, and subsequently, particles are detected in the circulating fluid. Whether those changes occur simultaneously or one after another has nothing to do with whether the changes are level-wise or pulse-like. Therefore, for example, it can happen that a level-wise change occurs in the amplitude and particulate substances are detected later. When particulate substances are detected, if the sampling section for analysis of particulate substances is close to the vibration detector, this detection occurs almost simultaneously. If these two sections are separate from each other, the particulate substances are detected with some delay which depends on the flow velocity. In any case, if monitoring is made only for vibration, a decision cannot be made whether or not the signal is generated by a fault of the vibration detector. By detection of something which indicates the quality of the circulating fluid, the presence or absence of an anomaly can be determined unfailingly; because this change in the fluid quality occurs in conjunction with the above-mentioned anomaly. Especially in the case of a temporary change as shown in Fig. 3, it is difficult to decide whether this phenomenon is noise detected by the detector which operates normally or anomaly has actually occurred. By use of this invention, true anomaly can be detected reliably. When abnormal vibration occurs in the devices, if the result is sent through the gaseous portion of the circulating liquid or a gas produced by processing the liquid is discharged to the outside, an abnormal change of the devices manifests as a change in the atmospheric environment around the circulating system. Like by detecting the quality.of the liquid, by monitoring the atmospheric environment of the circulating system, the presence or absence of anomaly can be detected surely. In the description of anomaly, vibration was used as means for detecting anomaly of the devices, but other available means for this detection are, for example, the temperature, sound, or the like of the devices, or the flow rate of the fluid. A method for surely determining an anomaly of concern by detecting the two states of the circulating system as the third embodiment for achieving the object of the present invention will now be described. Let us consider, for example, a case in which a heat exchanger or a heater is included in the devices constituting the circulation equipment. When an anomaly occurs in the heat exchanger or the heater, the temperature of the fluid changes. As the temperature of the liquid changes, the quality of water such as ion concentration, which is temperature-dependent, changes, so that by monitoring the water quality, the change of temperature can be confirmed with high accuracy. As has been described with reference to the first embodiment for achieving the object, depending on the kind of anomaly, the clad may sometimes be mixed in the liquid, which cannot be measured in terms of conductivity or ion concentration. In such a case, it is effective to analyze a particulate substance such as clad. For analysis of particulate substances, one method is to monitor the number of particles, concentration, particle size, or the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an equipment arrangement diagram of a basic embodiment of the present invention; Figs. 2A and 2B are correlation diagrams between the vibration of the devices and the particle number in the circulating system; Fig. 3 is a correlation diagram when there is a delay from the vibration of the devices to the particle number of the circulating system; Fig. 4 is a device arrangement diagram of an embodiment of anomaly diagnosis combining a radiation measuring method and vibration detection; Fig. 5 is a device arrangement diagram of an embodiment of anomaly diagnosis by a particle number counting method; Fig. 6 is a device arrangement diagram of an embodiment of anomaly diagnosis by a particle number density measuring method; Fig. 7 is a device arrangement diagram of an embodiment of anomaly diagnosis by a particle concentration measuring method; Fig. 8 is a device arrangement diagram of an embodiment of anomaly diagnosis by a particle component analysis method; Fig. 9 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle counting method and vibration detection; Fig. 10 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle number density measuring method and vibration detection; Fig. 11 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle concentration measuring method and vibration detection; Fig. 12 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle component analysis method and vibration detection; Fig. 13 is a device arrangement diagram of an embodiment of anomaly diagnosis combining a conductivity measuring method and a flow rate measuring method; Fig. 14 is a device arrangement diagran of an embodiment of anomaly diagnosis combining the radiation measuring method and the flow rate measuring method; Fig. 15 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle number counting method and the flow rate measuring method; Fig. 16 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the particle number counting method and the flow rate measuring method; Fig. 17 is a detailed device arrangement diagram of the anomaly determiner; and Fig. 18 is a device arrangement diagram of an embodiment of anomaly diagnosis combining the anomaly diagnosis apparatus and equipment operation control. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to Fig. 1 and Figs. 4 to 18. An embodiment of the present invention is shown in Fig. 1. Let us consider a nuclear power plant as an example of a circulating system 1 to which this invention is applied. In a circulation line of the circulating system 1, pure water is boiled in the core 61 of the nuclear reactor 60, the vapor is sent through themain vapor line 65 to drive a turbine 67, and then liquefied by a condenser 68. The condensate is passed through a condensate demineralizer 69 and converted into pure water, and after pre-heated by a feed water heater 66, the pure water returns to the nuclear reactor 60 through a feed water line 64. While the pure water is fed back to the nuclear reactor 60 by a recirculation system 62, the water purified by a reactor water purifier 63 is led to the feed water line 64. A vibration detector 10 mounted on the circulating system 1 detects vibration of the devices. To be more specific, in this embodiment, the vibration detector 10 detects the vibration of the recirculation system 62. The detected vibration is analyzed by a vibration analyzer 11 in terms of vibration level, frequency pattern, etc. Output of the vibration analyzer 11 is stored in a vibration reference value memory 12, and also input into an anomaly determiner. Due to the abnormal vibration of the devices, the particulate substances such as clad initially adhering to the internal walls of the devices or to the structural material near the devices come off and fall, and as a result, the number of particulate substances increases in the circulating water in the devices. The circulating liquid is led from the circulating system through a sampling line 9 to a particulate substance counter 22. In the particulate substance counter 22, the circulating liquid is led to a cell 71. An analyzing light 74 is emitted to the cell 71 by a light source 70. Therefore, when a particulate substance passes through the cell 71, the analyzing light 74 is scattered by the particulate substance, so that a scattered light is produced. The scattered light is detected by a detector 72, and a detection signal is sent to a signal processing unit 73. Detection signals are counted by the signal processing unit 73, and by this counting, the number of particulate substances that have passed the cell 71 can be counted. The output of the signal processing unit 73, or the counting result is used as output of the particulate substance counter 22. The particulate substance counter 22 sends the count of particulate substances in the liquid to the particle number reference value memory 23 to be stored therein and also to the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing input measured values with reference values, and determines anomaly when two variations exceed threshold levels. If one variation is very large, the other variation may be multiplied by a coefficient of weight to thereby lower the threshold level relative to the thus increased variation, under which condition a decision is made whether an anomaly has occurred. The output of the anomaly determiner 2 is supplied to a determination result display 3. In this embodiment, the sampling line 9 was provided in the recirculation system 62. However, the circulating system 1 may be regarded as comprising the core 61, the main vapor line 65, the turbine 67, condenser 68, condensate demineralizer 69, the feed water heater 66, and the feed water line 64, and the sampling line 9 may be provided between the condenser 68 and the condensate demineralizer 69, for example. In this case, there is a considerable distance between the recirculation system 62 to be constantly checked for vibration and the condenser 68 to which the sampling line 9 is connected, so that there is bound to be a delay from when the vibration detector 10 detects vibration until the particulate substance counter 22 detects a change in the number of particles. This is because this length of time is required for the circulating water to move through the core 61, the main vapor line 65 and the turbine 67. Therefore, in this case, the delay is taken into account and the time base is shifted by the amount corresponding to the delay, and decision is made whether an anomaly has occurred. The circulating system 1 may be regarded as comprising the core 61, the reactor water purifier 63 and the feed water line 64 and the sampling line 9 may be laid to be connected with the reactor water purifier 63. In this embodiment, a particle counter utilizing a light scattering phenomenon is adopted as the particulate substance counter 22, but it is also possible to use filters with different pore sizes to collect particulate substances in separate groups of different particle sizes and measure their radioactivity. Or, a breakdown-system particle counter may be adopted. According to this embodiment, a measuring method is adopted on particulate substances that fall off as the vibration level of the devices increases, so that measurement can be done in-line to quickly diagnose anomaly of the equipment with rapidity and high reliability. Another embodiment is shown in Fig. 4. In this embodiment, the circulating system 1 is regarded as comprising the core 61, the main vapor line 65, the turbine 67, the condenser 68, the condensate demineralizer 69, the feed water heater 66, and the feed water line 64, and the vibration detector 10 is attached to the feed water line 64, and detected vibrations are analyzed by the vibration analyzer 11 in terms of vibration level, frequency pattern, etc. The output of the vibration analyzer 11 is stored in the vibration reference value memory 12, and also input to the anomaly determiner 2. When abnormal vibration occurs in the devices of a nuclear power plant, a crack has opened the devices, so that chromate ions or the like dissolve out from the crack, changing the quality of the circulating water to the acid side. On the other hand, the circulating water normally contains nitrogen molecules (N₂) in solution, but when the water quality is acidified, the solubility of N₂ decreases, and the supersaturated portion of N₂ goes to the gaseous phase. The circulating water of the nuclear reactor contains some of radioactive ¹⁶N, so that N₂ which goes to the gaseous phase contains ¹⁶N. Radiation can be detected on the¹⁶N in the gaseous phase. So, the dosage included in the medium of the circulating system is detected with a radiation detector 20. The radioactivity level detected by the radiation detector 20 is stored in the radioactivity reference value memory 21, and also input into the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing input measured values with reference values, and determines an anomaly when two variations exceed threshold levels. At this time, if one variation is very large, the other variation may be multiplied by a coefficient of weight to thereby lower the threshold level relative to the increased variation, under which condition a decision is made whether an anomaly has occurred. The output of the anomaly determiner 2 is supplied to the determination result display 3. In order to detect a phenomenon that the quality of the circulating water changes in consequence of abnormal vibration of the devices, the conductivity or the hydrogen ion concentration (pH) may be measured. According to this embodiment, an increase in radioactivity level of radioactive elements is detected which attends on an increase in vibration level of the devices, so that an anomaly of the equipment can be diagnosed with high reliability. Another embodiment is shown in Fig. 5. In this embodiment, for diagnosis of an anomaly of the circulating system, an arrangement is made so as to adopt a particulate substance counting method. The circulating liquid is led from the circulation equipment 1 through the sampling line 9 to the particulate substance counter 22. The particulate substance counter 22 counts particulate substances in the liquid, and the counting result is stored in the particle number reference value memory 23, and also input into the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing an input measured value with a reference value, and outputs anomaly when a variation exceeds a threshold level. Output of the anomaly determiner 2 is supplied to the determination result display 3. In this embodiment, one particulate substance counter 22 is used, but it is possible to set a plurality of sampling points by combining sampling lines 9 and particulate substance counters 22, and subdivide the circulating system 1 to assume a position in the circulating system 1 where anomaly has occurred. In this embodiment, a measuring method on particulate substances that come off and fall due to anomaly of the equipment, so that the measurement can be done in-line and anomaly of the circulating system 1 can be diagnosed quickly. Yet another embodiment is shown in Fig. 6. In this embodiment, an arrangement is made to adopt a particle number density measuring method of particulate substances for anomaly diagnosis. of the circulating system 1. The circulating liquid is led.from the circulating system through the sampling line 9 to the particle number density measuring unit measures a number density of particulate substances in the liquid, and the result is stored in the particle number density reference value memory 25 and alsoenteredinto the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing an input measured value with a reference value, and outputs anomaly when a variation exceeds a threshold level. Output of the anomaly determiner 2 is supplied to the determination result display 3. In this embodiment, a method of measuring particulate substances that come off and fall due to anomaly of the equipment, and therefore, measurement can be made in-line to diagnose an anomaly in the circulating system 1. Fig. 7 shows a still another embodiment. In this embodiment, an arrangement is made to adopt a particulate substance density measuring method for anomaly diagnosis of the circulating system 1. The liquid that circulates through the sampling line 9 from the circulating system 1 is led to the particle number density measuring unit 24 and the particle size distribution measuring unit 26. The particle number density measuring unit 24 measures a number density of particulate substances in the liquid, and at the same time, the particle size distribution measuring unit 26 measures a particle size distribution of particulate substances. The measurement results of the particle number density measuring unit 24 and the particle size distribution measuring unit 26 are input to a concentration conversion unit 27 where a concentration of the particulate substances is calculated. The calculation result is stored in a particulate substance concentration reference value memory 28 and also supplied to the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing an input measured value and a reference value, and indicates an anomaly when a variation exceeds a threshold level. The output of the anomaly determiner 2 is supplied to the determination result display 3. In this embodiment, a method is adopted to measure particulate substances that come off and fall due to an anomaly of the equipment, so that measurement is made in-line to quickly diagnose an anomaly of the circulating system 1. Still another embodiment is shown in Fig. 8. In this embodiment, an arrangement is made to adopt a particulate substance component analysis method for anomaly diagnosis of the circulating system 1. The circulating liquid is led from the circulating system 1 through the sampling line 9 to a particulate substance component analysis unit 29. The particulate substance component analysis unit 29 measures components of the particulate substance in the liquid, and the measurement results are stored in a component ratio reference value memory 30, and also input to the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing an input measured value with a reference value, and outputs anomaly when a variation exceeds a threshold level. Output of the anomaly determiner 2 is supplied to the determination result display 3. In this embodiment, a method of analyzing the components of the particulate substances that come off and fall due to anomaly of the equipment, which makes it possible to perform measurement in-line to quickly diagnose anomaly of the circulating system 1. A further embodiment is shown in Fig. 9. In this embodiment, the vibration detector 10 mounted on the circulating system 1 detects a vibration of the devices included in it. The detected vibration is analyzed by the vibration analyzer 11 in terms of vibration level, frequency pattern, etc. Output of the vibration analyzer 11 is stored in the vibration reference value memory 12, and also input to the anomaly determiner. The liquid circulating through the sampling line 9 from the circulating system 1 is led to the particulate substance counter 22. The particulate substance counter 22 counts particulate substances in the liquid, and the counting results are stored in the particle number reference value memory 23 and also input to the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing input measured values with reference values, and determines anomaly when both variations exceed threshold levels. In this determining process, if one variation is very large, the other variation may be multiplied by a coefficient of weight to lower the threshold level relative to the thus increased variation, under which condition a decision is made whether an anomaly has occurred. The output of the anomaly determiner 2 is supplied to the determination result display 3. According to this embodiment, it is possible to diagnose with high reliability and rapidity an anomaly of the equipment from an increase in the number of particles that come off and fall owing to the vibration of the devices. A still further embodiment is shown in Fig. 10. The basic arrangement of this embodiment is the same as shown in Fig. 9. However, in place of the particulate substance counting method, this. embodiment is arranged to adopt a method of measuring a number density of particulate substances shown in Fig. 6. According to this embodiment, it is possible to diagnose with high reliability and rapidity anomaly of the equipment from an increase in the number density of particles that come off and fall caused by the vibration of the devices. Another embodiment is shown in Fig. 11. The basic arrangement of this embodiment is the same as shown in Fig. 9. However, this embodiment is arranged to use a method of measuring the concentration of particulate substances as shown in Fig. 7 in place of the particulate substance counting method. According to this embodiment, it is possible to diagnose with high reliability and rapidity an anomaly of the equipment from an increase in the concentration of particles that come off and fall caused by the vibration of the devices. A still further embodiment is shown in Fig. 12. The basic arrangement of this embodiment is the same as shown in Fig. 9, but this embodiment is arranged to adopt a method of analyzing the components of the particulate substances shown in Fig. 8 in place of the particulate substance counting method. According to this embodiment, it is possible to diagnose with high reliability and rapidity anomaly of the equipment from a change in the component ratio of particles that come off and fall as the vibration of the devices increases. Yet another embodiment is shown in Fig. 13. In this embodiment, the flow rate of the circulating liquid is measured with a flow meter 13. The measurement results of the flow meter 13 are stored in a flow rate reference value memory 14 and also input into the anomaly determiner. On the other hand, a part of the structural material of the piping is ionized and dissolves out from the pipe walls or the like into the circulating liquid. The degree of elution can be detected in terms of ion concentration in the circulating liquid, namely, conductivity of the liquid. When the temperature and the quality of the liquid are fixed, the elution speed of the ions is constant. Therefore, the conductivity changes dependent upon the quantity, that is, the flow rate of the circulating water that passes per unit time, and as the flow rate decreases, the conductivity increases. The conductivity of the circulating liquid is measured with a conductivity meter 31, and the measurement results are stored in a conductivity reference value memory 32, and also input into the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing input measured values with reference values, and determines anomaly when both variations exceed threshold levels. If one variation is very large, the other variation may be multiplied by a coefficient of weight to lower the threshold level relative to the thus increased variation, under which condition a decision is made whether an anomaly has occurred. The output of the anomaly determiner 2 is supplied to the determination result display 3. According to this embodiment, it is possible to measure in-line a decrease in conductivity attending on an increase in the flow rate in the devices or an increase of conductivity attending on a decrease in the flow rate, so that the state of a valve 8 can be presumed and anomaly of the valve 8 can be diagnosed with high reliability and rapidity. An additional embodiment is shown in Fig. 14. In this embodiment, a flow rate of the circulating liquid is measured with a flow meter 13. The measurement results of the flow meter 13 are stored in the flow rate reference value memory 14 and also input into the anomaly determiner. On the other hand, when the flow rate changes, the amount of ¹⁶N that moves to the gaseous state also changes, so that the radioactivity level of the medium changes. So, the radiation dose contained in the medium of the circulating system 1 is detected with the radiation detector 20. The radioactivity level detected with the radiation detected by the radiation detector 20 is stored in the radioactivity reference value memory 21, and input into the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state by comparing input measured values with reference values, and determines an anomaly when both variations exceed threshold levels. If one variation is very large, the other variation may be multiplied by a coefficient of weight to lower the threshold level relative to the increased variation, under which condition a decision is made whether anomaly has occurred. Output of the anomaly determiner 2 is supplied to the determination result display 3. According to this embodiment, it is possible to measure in-line an increase in radioactivity level attending on an increase in the flow rate in the devices or a decrease in radioactivity level attending on a decrease in the flow rate, so that the state of the valve 8 can be presumed and anomaly of the valve 8 can be diagnosed with high reliability and rapidity. Another embodiment is shown in Fig. 15. The basic arrangement of this embodiment is the same as shown in Fig. 13. However, as the flow rate changes, the number of particles that move per unit time also changes, so that the anomaly diagnosis apparatus is arranged so that both the flow rate and the number of particles are measured. According to this embodiment, it is possible to measure in-line an increase in the number of particles attending on an increase in the flow rate of the equipment or a decrease in the number of particles attending on a decrease in the flow rate, and therefore, the state of the valve 8 can be presumed and an anomaly of the valve 8 can be diagnosed with high reliability and rapidity. Next, still another embodiment is shown in Fig. 16. In this embodiment, a temperature of the liquid circulating from the circulating system 1 is measured with a thermometer 15. The measured temperature value is stored in a temperature reference value memory 16 and input into the anomaly determiner 2. On the other hand, the breaking-away behavior of the particulate substances has temperature dependency, and they are more likely to break away at higher temperature, so that the number of particles varies with changes of temperature in the circulating system. Therefore, the number of particles in the circulating liquid which is led to the particulate substance counter 22 is counted with the particulate substance counter 22, and the counting results are stored in the particle number reference value memory 23, and also input into the anomaly determiner 2. The anomaly determiner 2 is constantly detecting any change from the measured levels in steady state, and determines anomaly when both variations exceed threshold levels. If at this time one variation is very large, the other variation may be multiplied by a coefficient of weight to lower the threshold level relative to the increased variation, under which condition a decision is made whether an anomaly has occurred. Output of the anomaly determiner is supplied to the determination result display 3. In this embodiment, a method is adopted for measuring broken-away particulate substances that increase as the temperature of the circulating liquid rises, so that measurement can be performed in-line and anomaly of the circulating system 1 can be diagnosed with rapidity. Yet another embodiment is shown in Fig. 17. This embodiment indicates a detailed arrangement of the anomaly determiner which has been referred to in the foregoing description. With regard to quantity A under observation for detecting variation, a reference value A 80 and a measured value A 81 are input into a variation analyzer A 84. On the other hand, with regard to quantity B under observation, a reference value B 82 and a measured value B 83 are input into a variation analyzer B 85. The variation analyzer A 84 evaluates only the variation of the quantity A, and compares the variation with a threshold value set initially. As a result of comparison, the variation analyzer A 84 outputs analysis result A 86 such as information about whether the variation exceeds the threshold value, the degree of variation or the like. A similar process is performed also for the quantity B. The analysis result A 86 and analysis result B 87 are input into an analysis result comprehensive evaluation unit 88. The analysis result comprehensive evaluation unit 88 evaluates the analysis result A 86 and the analysis result B 87, and outputs "anomaly" when variations of both quantities under observation exceed the threshold values. On the other hand, even when the variation exceeds the threshold value in information about, for example, the analysis result A 86, if the variation does not exceed the threshold value in the analysis result B, the analysis result comprehensive evaluation unit 88 outputs "non-anomaly", and at the same time, outputs anomaly of the measuring system itself with regard to the quantity A under observation, and suggests a need for inspection of the measuring instrument to the operator. However, it is possible to make an arrangement that when the variation exceeds twice the threshold value, for example, in the analysis result A 86, the threshold value used for comparison and decision in the analysis result B 87 is lowered, a comparison is made between the reference value B 82 and the measured value B 83, and if the variation of the quantity B is larger than the newly-set threshold value, the analysis result comprehensive evaluation unit 88 outputs "anomaly". By the arrangement of this embodiment, a plurality of quantities under observation are observed, not only diagnosis can be performed with high reliability, but even when an anomaly occurs in one of the quantities under observation, a decision can be made whether the variation is a true "anomaly" or the measuring instrument is abnormal. A still another embodiment is shown in Fig. 18. In this embodiment, the anomaly diagnosis system 50 shown in Fig. 1 and Figs. 4 to 17 is arranged to be provided additionally with an output control unit 17 and an emergency stop unit 18. When the anomaly diagnosis system 50 outputs "anomaly", output-controlled operation of the plant can be performed in compliance with the "anomaly" level or the plant operation can be stopped in an emergency stop. By the arrangement of this embodiment, there is no process where the operator has to make a decision as to anomaly, so that the time for responding to a plant anomaly can be shortened substantially and the anomaly can be prevented from spreading. According to the present invention, an anomaly of facilities such as a nuclear power plant can be diagnosed with high reliability, a fact which makes it possible to greatly improve the safety control technology of the facilities which require monitoring, such as nuclear power plants, chemical plants, and so on.

Claims: A plant diagnosis apparatus comprising: first detecting means (10, 11, 12, 13, 14, 15, 16) for detecting a state of devices constituting a circulating system (1) in which a fluid circulates; second detecting means (20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32) for detecting a physical or chemical property of the circulating fluid caused by and indicative of impurities in said circulating fluid or a physical or chemical property of atmosphere around said circulating system (1); and means (2) for diagnosing said circulating system (1) from a correlation between outputs of said first and second detecting means. A plant diagnosis apparatus according to claim 1, wherein said second detecting means comprises means (22, 23, 24, 25, 26, 27, 28, 29, 30) for detecting particulate substances in said circulating fluid. A plant diagnosis apparatus according to claim 1, wherein said first detecting means comprises means (13, 14, 15, 16) for detecting a flow rate or a temperature of said circulating fluid so as to indirectly detecting said state of said devices. A plant diagnosis apparatus according to claim 1, wherein said first detecting means comprises means (10, 11, 12) for detecting a vibrating condition of said devices. A plant diagnosis apparatus according to claim 1, wherein said second detecting means comprises means (31, 32) for detecting a conductivity or pH values of said circulating fluid. A plant diagnosis apparatus according to claim 1, wherein said means for diagnosing comprises: a first diagnosing means (84) for diagnosing whether or not an anomaly of said devices is present according to an output of said first detecting means; and a second diagnosing means (85) for diagnosing whether or not the diagnostic result of said first diagnosing means is correct according to an output of said second detecting means. A plant diagnosis apparatus according to claim 6, wherein said second diagnosing means comprises means (88) for diagnosing whether or not the diagnostic result of said first diagnosing means is correct after a predetermined time has elapsed since an anomaly has been detected in said first detecting means. A plant diagnosis apparatus according to claim 1, wherein said circulating system is a primary cooling system of a nuclear power plant, and wherein said second detecting means comprises means (22, 23, 24, 25, 26, 27, 28, 29, 30) for detecting a physical or chemical property of cooling water flowing in said primary cooling system. A plant diagnosis apparatus according to claim 1, wherein said circulating system is a primary cooling system of a nuclear power plant, and wherein said second detecting means comprises means (20, 21) for detecting a radiation dose of the atmosphere around said primary cooling system. A plant diagnosis apparatus according to claim 1, wherein said circulating system is a primary cooling system of a nuclear power plant, and wherein said second detecting means comprises means (22, 23, 24, 25, 26, 27, 28, 29, 30) for detecting particulate substances in cooling water flowing in said primary cooling system. A method of diagnosing a circulating system in which a fluid circulates, comprising the steps of: obtaining first information concerning state of devices constituting said circulating system (1); obtaining second information concerning a physical or chemical property of the circulating fluid flowing in said circulating system or a physical or chemical property of atmosphere around said circulating system; and diagnosing said circulating system according to said first and second information. A method of diagnosing a circulating system according to claim 11, wherein said diagnosing step comprises the steps of: diagnosing whether or not an anomaly of said devices is present according to said first information; and diagnosing whether or not the result of diagnosis according to said first information is correct according to said second information which was obtained after a predetermined time since an anomaly of said devices has been detected.

Inventors: ASAKURA YAMATO, IBE HIDEFUMI, KAMIMURA HIROSHI, MATSUI TETSUYA, NAGASE MAKOTO, NISHINO YOSHITAKA, UCHIDA SHUNSUKE, YOKOSE KENJI, ASAKURA, YAMATO, IBE, HIDEFUMI, KAMIMURA, HIROSHI, MATSUI, TETSUYA, NAGASE, MAKOTO, NISHINO, YOSHITAKA, UCHIDA, SHUNSUKE, YOKOSE, KENJI
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1992
Main classification: G21C17
IPC codes: G05B23, G21C17, G01D21