Patent Number: 056231091
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to a monitoring and diagnosing method and system which monitor and diagnose the condition and operation of plants such as nuclear power plants and thermoelectric power plants. There are various kinds of plants for producing energy and reaction products, e.g., nuclear power plants using boiling water reactors and pressurized water reactors, thermoelectric power plants in which petroleum, coal, natural gas, etc. are burnt, and chemical plants for producing and refining petrochemicals such as ethylene (hereinafter these different types of plants referred to simply together as plants). In these plants, objects to be controlled are subject to a wide temperature range from low to high temperatures, and phase of the objects is changed from liquid to gas phase and, in some cases, even to solid phase at different locations within each plant. For each condition of start-up, steady operation and shut-down of a plant, the temperature and phase of the controlled object are variously changed at different locations within the plant. Generally, the operation of a plant is controlled by a computer. In order to achieve optimum operation efficiency of the plant or smooth start-up and shut-down thereof, various variables in the plant such as pressure and temperature are measured every moment, and the plant is operated under control of the computer so that the various variables are optimized. FIG. 16 is a schematic structural view of main apparatus and equipment of a nuclear power plant using a boiling water reactor. In FIG. 16, reactor internals such as a fuel assembly and a jet pump 22 are disposed in a pressure vessel 17. The pressure vessel 17 is housed in a reactor containment vessel 16 along with other main apparatus and equipment for controlling and cooling the reactor, such as a control rod drive unit and a recirculation pump motor 29. During normal operation, control rods are withdrawn from a core 23 so that nuclear fission of uranium as the fuel reaches critical mass to produce heat. The jet pump 22 is driven by the recirculation pump motor 29 disposed in a recirculation loop 26, whereby cooling water is circulated to remove the heat generated by the nuclear fission from the core. Then, high-pressure steam at 280.degree. C. and 6.9 MPa is produced and supplied to a turbine through a main steam line 24 for driving the turbine to thereby generate electricity. The steam is condensed by a condenser into water that is returned to the reactor through a feed-water line 25. During the operation, nitrogen gas is filled into the reactor containment vessel 16 for the purpose of noncombustibility. If any abnormality should occur in the reactor system, the reactor is shut down and the reactor system is isolated within the reactor containment vessel 16 by operating main steam isolation valves installed inside and outside of the reactor containment vessel 16. Also, any overpressure in the reactor is relieved through a safety release valve 18, and safety equipment such as an emergency core cooling system is operated. Denoted by reference numeral 21 is a shroud disposed to surround the core 23. Further, 20 is a steamy water separator, 37 is a dry well, and 19 is a steam drier. The steam water separator 20 serves to remove condensed water, and the dry well 37 serves to release a steam/water mixture in the event of loss-of-a-coolant accident. 28 is a coolant purifying pump which supplies a coolant to the feed-water line 25 through a filter/demineralizer 27. 15 is a reactor containment vessel spray for scattering cooling water, and 30 is a similar spray. 31 is a turbine pump for cooling in the event of isolation. In case of the reactor becoming isolated from the turbine system, the pump 31 serves to cool the reactor. Further, 32 is a residual heat removal unit and 36 is a residual heat removal pump, the heat exchanger 32 and the pump 36 serving to remove the decay heat after shut-down of the reactor. 33 is a high-pressure core spray pump, 34 is a low-pressure core spray pump, and 35 is a pressure suppression chamber. In the above-described nuclear power plant, the operation of the nuclear power plant is periodically shut down and the main equipment and apparatus are dismantled and disassembled to check for the presence or absence of an abnormality and any degree of deterioration for the purpose of ensuring reliability of the nuclear power plant. Also, the presence or absence of an abnormality is checked in a nondestructive manner and, if any abnormality is found, the relevant apparatus and/or parts are repaired or replaced with new ones, thereby ensuring reliability in the operation of the nuclear power plant. In the nuclear power plant during the operation, the operating condition represented by parameters primarily related to the reactor, such as power, temperature, pressure and flow rate of circulating water, are monitored at all times. Based on the monitored results, it is confirmed that the operating condition of the nuclear power plant is normal. For each of the pumps and other main components, such parameters as rotational speed, delivery pressure, temperature and flow rate are monitored to confirm the operating condition thereof. In addition, not only the vibrations and temperature of each apparatus, but also leaked steam, water, radioactive rays, etc. around the apparatus are monitored to confirm that the environment surrounding the apparatus is normal. Thus, the presence or absence of an abnormality in the operation of the nuclear power plant is always confirmed. For periodic inspection of the equipment and apparatus, the advanced checking operation is promptly performed by expert workers having advanced skills in conformity with legal check items. FIGS. 17A-17D is a table showing a summary of methods for diagnosing the main apparatus and equipment, and FIG. 18 is a table of main sensors for diagnosis of the main apparatus and equipment (reference: "Equipment Diagnosing System of Nuclear Power Plants", Uchida and three others, Sensor Technology, October 1992, pp. 84-89). As the prior art relating to monitoring and diagnosis of plants and apparatus, there are known, for example, patent laid-open publications concerned with apparatus (JP, A, 58-134312 and JP, A, 3-220498) and with plants (JP, A, 58-215593, JP, A, 63-313208 and JP, A, 63-241876). In these publications, a prediction model for the operation of an apparatus or plant to be monitored is utilized to detect an abnormality from the difference between the model and actually observed results. SUMMARY OF THE INVENTION Meanwhile, it has been recently desired to improve reliability of plants such as nuclear power plants and to increase an availability factor of plants by simplification of the periodic inspection. There is a fear in the future that as plants such as nuclear power plants are aged year by year, the occurrence of troubles due to deterioration of apparatus and materials over time will lower the reliability of the plant. Also, it is expected that the number of expert workers necessary for the periodic inspection of the plant will be insufficient. It will therefore be necessary to efficiently predict a possibility of the occurrence of an abnormality in apparatus and materials with high reliability during the operation of the plant. It is also required to sense an abnormality of apparatus and so on in the very early stage. Accordingly, there is a demand for accurate and automatic monitoring and diagnosis of plant equipment which can suppress a reduction in reliability of plants due to deterioration of apparatus and materials over time, can suppress a reduction in the availability factor due to the periodic inspection, and can exactly grasp time-dependent characteristics of plants. To improve reliability in monitoring and diagnosing highly complicated facilities such as nuclear plants, for example, a function of exactly analyzing and diagnosing an abnormality, taking into account the personality of each plant including its production record, check/repair record and operation record, is indispensable. In addition, not only a function of processing the data to promptly and surely analyze many kinds of and a large number of monitored data and detect an abnormality, but also a function of surely transmitting the result of diagnosis and the measures to be dealt with to operators are also necessary. Then, an overall monitoring and diagnosing system in which the analyzing and diagnosing functions and the transmitting function are coupled to each other is desired. In the above-described prior art, however, a monitoring and diagnosing method which can exactly analyze and diagnose an abnormality, taking into account the personality of a plant including its production record, check/repair record and operation record, has not yet been realized. Accordingly, an object of the present invention is to realize a plant monitoring and diagnosing method and system which can exactly analyze and diagnose an abnormality with high reliability, taking into account the production record, the check/repair record, the operation record, etc. of a plant, and can simplify the periodic inspection to increase an availability factor of the plant. To achieve the above object, the present invention is arranged as follows. In a plant monitoring and diagnosing method, detecting and accumulating plant operating conditions, apparatus operating conditions and environment conditions, inputting and accumulating plant inspection data, and monitoring and diagnosing plant conditions based on plant record information including the accumulated detection data and inspection data. In the above plant monitoring and diagnosing method, preferably, the plant record information is stored in the form of a plant chart in which the detection data and the inspection data are compressed and accumulated such as a personal clinical chart, and the plant conditions are diagnosed based on the data in the plant chart. In the above plant monitoring and diagnosing method, preferably, current plant conditions are predicted in accordance with the data in the plant chart and a plant condition predicting model, and an abnormality in the plant conditions are monitored and diagnosed based on a comparison between the predicted current plant conditions and the current detection data. Also, in the above plant monitoring and diagnosing method, preferably, when an abnormality is detected as a result of diagnosing the plant conditions, an abnormal location and an abnormal item are identified and events which will ensue from the abnormality are predicted. In the above plant monitoring and diagnosing method, preferably, the identified abnormal location and item and the event incidental to the abnormality are indicated by display means. Also, in the above plant monitoring and diagnosing method, preferably, a countermeasure for dealing with the detected abnormality is selected, and the identified abnormal location and item, the event incidental to the abnormality, and the countermeasure are indicated by display means. Further, in the above plant monitoring and diagnosing method, preferably, a residual life for each plant component, apparatus and member is evaluated based on the data in the plant chart and material degradation data calculated from the chart data. In a plant monitoring and diagnosing system, the system comprises first input means for receiving detection data of plant operating conditions, apparatus operating conditions and environment conditions, second input means for receiving plant inspection data, first input data processing means for preparing data for use in plant monitoring and diagnosis based on the detection data from the first input means, second input data processing means for preparing data for use in plant monitoring and diagnosis based on the inspection data from the second input means, a plant chart for storing the data prepared by the first and second input data processing means, and monitoring and diagnosing means for monitoring and diagnosing the plant conditions based on the data stored in the plant chart. In the above plant monitoring and diagnosing system, preferably, the monitoring and diagnosing means includes abnormality diagnosing means for diagnosing a plant abnormality based on the data from the plant chart and the data from the first input data processing means. Also, in the above plant monitoring and diagnosing system, preferably, the abnormality diagnosing means diagnoses an abnormality in the plant operating conditions and the plant apparatus operating conditions. Further, in the above plant monitoring and diagnosing system, preferably, the abnormality diagnosing means identifies an abnormal plant location and an abnormal item and predicts ensuring events. Preferably, the above plant monitoring and diagnosing system further comprises display means for displaying the abnormal location, the abnormal item and the ensuring events identified and predicted by the abnormality diagnosing means. Also, in the above plant monitoring and diagnosing system, preferably, the abnormality diagnosing means selects a countermeasure for dealing with the location and details of the abnormality, and the display means displays the selected countermeasure. In the plant monitoring and diagnosing method, plant operating conditions, apparatus operating conditions and environment conditions are detected and accumulated, and detection data are inputted and accumulated. The accumulated detection data and inspection data are stored as plant record information. The plant conditions are monitored and diagnosed based on the plant record information. Therefore, when the record information shows detection of abnormal signs or the like in the past, for example, the monitoring and diagnosis are performed in consideration of the past data even if the current condition is sound. When an abnormality is detected, the location and details of the abnormality are identified and ensuing events are predicted. In the plant monitoring and diagnosing system, plant operating conditions, apparatus operating conditions and environment conditions are input through first input means. Also, inspection data are input through second input means. Data for use in plant monitoring and diagnosis are prepared by first and second data processing means based on the detection data from the first and second input means. The data prepared by the first and second data processing means are stored in a plant chart. Then, the plant conditions are diagnosed by monitoring and diagnosing means based on the data stored in the plant chart.