JPH08320307A - Degradation-detection sensor and its measuring method - Google Patents

Abstract

PURPOSE: To obtain a degradation detection sensor which can monitor a degradation degree under the same condition as a data-base, by which the accuracy and the reliability of the evaluation of a remaining life are enhanced and by which the replacement time and the repair time of an apparatus material can be decided on the safer side. CONSTITUTION: A weld 11 whose degradation in a nuclear plant is estimated to be remarkable is provided with a surveillance sample 12 whose degradation has been accelerated more than that of the weld 11, and a magnetic signal is monitored by a monitor at the outside of the nuclear plant. The magnetic signal is compared with a data-base which has been found in advance, a degradation degree is found, and whether the weld is to be replaced or repaired is decided by whether the degradation degree exceeds a replacement reference value or not. In addition, the surveillance sample 12 is measured under the same sample condition and the same measuring condition as in the construction of the data-base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power plant, and more particularly to a deterioration detecting device suitable for evaluating the remaining life of nuclear plant equipment materials and prolonging its life.

[0002]

2. Description of the Related Art Conventionally, in a deterioration diagnosis technique for a nuclear power plant, as described in JP-A-1-147360 and JP-A-63-212844, a magnetic or electrical signal of a plant actual equipment is detected. The degree of deterioration of the actual plant equipment was estimated by direct measurement and comparison with a previously obtained database of the relationship between the magnetic or electrical signal of the simulated material and the material strength. Further, as shown in Japanese Patent Application No. 63-228735, a micro sample is directly collected from the actual equipment of the plant, and the deterioration degree of the actual equipment is detected by measuring the strength and structure of the sampling material. It was

[0003]

[Patent Document 1] Japanese Patent Application Laid-Open No. 1-147360
Further, in Japanese Patent Laid-Open No. 63-212844, there is a margin for directly evaluating the deterioration of plant equipment materials, and there is a possibility that the replacement time of equipment materials may not be appropriate. Further, since the measurement conditions of the database obtained in advance and the measurement conditions of the actual machine member are different, there is a problem that the accuracy and reliability of deterioration diagnosis decrease. Furthermore, since the deterioration is measured only during the periodic inspection, it is not possible to detect an abnormality between regular inspections.

In Japanese Patent Application No. 63-228735, the actual material of the plant is directly sampled, so that the sampling has a considerable effect on the actual equipment. There is also a problem in that the surface of the actual machine member after sampling must be repaired.

[0005]

In order to solve the above problems of the conventional method, the present invention employs the following technical means. In other words, in order to provide a margin for deterioration diagnosis of actual machine parts, the actual machine parts are not directly measured, but the deterioration degree of the actual machine parts is determined from the database of magnetic properties and electrical characteristics and material strength that were obtained in advance for the actual machine parts. It is estimated that a surveillance material having a deterioration degree higher than the above-described deterioration degree is manufactured and installed in the vicinity of the actual machine member. Further, a sensor for measuring magnetic or electrical characteristics under the same conditions as when measuring the database is mounted near the surveillance material. Here, the measurement conditions such as the size and shape of the surveillance material, the surface state, and the positional relationship between the surveillance material and the sensor are all the same as the measurement conditions when the database was constructed. A magnetic or electrical signal from a so-called accelerated deterioration sensor, which is a combination of the above surveillance materials and sensors, is taken out from the nuclear power plant and monitored outside the plant. The magnetic or electrical signal from the surveillance material that is deteriorated compared to the actual equipment is the threshold value (design standard value or replacement standard value) in the relationship between the magnetic property or electrical property and the material strength that have been obtained in advance. If it becomes larger than the above, it is judged to be abnormal and repair or replacement of the actual machine member is performed.

[0006]

[Function] Since the surveillance material is deteriorated compared to the actual equipment material, even if the magnetic or electrical signal of the surveillance material reaches the threshold value of the database, it is possible to repair or replace the actual equipment on the safety side. . In addition, since the measurement conditions such as the form and dimensions of the surveillance material, the processing conditions, and the positional relationship between the surveillance material and the sensor are all the same as the measurement conditions when the database was constructed, the measurement error between them is reduced, The accuracy and reliability of deterioration diagnosis are improved. Since the degree of deterioration can be continuously evaluated even during plant operation, it is possible to detect abnormalities that occur during regular inspections. Further, since the surveillance material is measured, it is possible to estimate the repair or replacement time of the actual machine member nondestructively.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a deterioration detecting sensor of the present invention. In a nuclear power plant, for example, in a weld 11 that is expected to deteriorate, a surveillance sample 12 made of the same material as the weld 11 that is further deteriorated than the weld 11 that is expected
Will be installed at the time of regular inspection. SQU for surveillance sample 12
A magnetic detection sensor 13 such as an ID is installed, or an electric detection sensor 13 is provided. Surveillance sample 1
The sensor 2 and the detection sensor 13 are housed in a lead case 14 to protect the sensor from neutron irradiation 15 and reactor water 16 and reduce external noise 17. Further, the whole is mounted in the sensor housing 18. The sensor housing 18 is made of a mesh material and allows the reactor water 16 to freely enter and leave. Further, the surveillance sample 12 needs to have the same sample size and morphology as the conditions for which the database of the relationship between the magnetic or electrical signal and the material strength, which has been obtained in advance, is obtained, and the same surface treatment must be performed. Degradation events of the surveillance sample and the magnetic detection sensor include irradiation embrittlement, age embrittlement, and stress corrosion cracking. The positions where these so-called acceleration surveillance sensors 19 are attached are the positions of the equipment members where the deterioration determined by a statistical method such as extreme value statistics is estimated to occur most severely. Acceleration surveillance sensor 19
Is transmitted to the outside of the nuclear power plant 21 through the optical fiber 22 as shown in FIG.
Always monitor magnetic or electrical signals on the 3.

On the monitor 23, as shown in FIG. 3 in the case of irradiation embrittlement with magnetic output or electric output previously obtained, as shown in FIG. As shown in FIG. 4, the irradiation rate 31 and the aging degree 41 of the acceleration surveillance sensor are estimated from the relationship with the aging parameters (determined from the aging time and temperature of the material, and the material composition). In the case of the neutron irradiation rate shown in FIG. 3, the extrapolation curve 33 of the acceleration surveillance sensor having a margin greater than that of the data curve.
Set. Moreover, even in the case of the aging parameter of FIG.
An extrapolation curve 43 of the acceleration surveillance sensor having a tolerance from the database curve 42 is determined, and the aging degree 41 of the acceleration surveillance sensor is obtained. Here, since the acceleration surveillance sensor 19 is set under almost the same conditions as the measurement conditions for which the database is obtained, the reliability of the estimated value is enhanced. Further, as shown in FIG. 5, the fracture toughness value 51, etc. Estimate material strength. When the estimated value becomes smaller than the design reference value or the replacement reference value 51, the welded portion 11 is replaced or the welded portion 11 is repaired. Further, instead of constantly monitoring the magnetic or electrical signal from the acceleration surveillance sensor 19 outside the nuclear power plant, it is also possible to take out the deterioration degree appropriately at the time of regular inspection.

In this embodiment, since the deterioration site of the nuclear plant equipment material is not directly monitored and the magnetic or electrical signal of the simulated sample in which the deterioration is accelerated is measured, the deterioration degree can be evaluated on the safe side. . Further, since the degree of deterioration of the acceleration surveillance sensor can be adjusted according to the deterioration event or the deteriorated portion, it is possible to freely select the margin of the remaining life evaluation of the equipment material, replacement, and repair time.

[0011]

According to the present invention, it is possible to evaluate the remaining life of the deteriorated part from the deterioration degree of the surveillance which is accelerated more than the deterioration degree of the deteriorated part without directly monitoring the deteriorated part of the nuclear power plant. The replacement time and repair time of the deteriorated part can be determined on the safer side. Moreover, since the monitoring is performed under the same conditions as the database, the accuracy of the remaining life evaluation is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a deterioration detection sensor of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a deterioration detection sensor and an external monitor.

FIG. 3 is a characteristic diagram showing a relationship between a magnetic signal of a database and an acceleration surveillance sensor and a neutron irradiation rate.

FIG. 4 is a characteristic diagram showing a relationship between a magnetic signal of a database, an acceleration surveillance sensor, and an aging parameter.

FIG. 5 is a characteristic diagram showing the relationship between the deterioration parameter and the fracture toughness value of the database and the acceleration surveillance sensor, and the relationship between the design standard and the replacement standard.

[Explanation of symbols]

11 ... Welded portion, 12 ... Surveillance sample, 13 ... Detection sensor, 14 ... Lead case, 15 ... Neutron irradiation, 16 ... Reactor water, 17 ... External noise, 18 ... Sensor housing, 19
… Acceleration surveillance sensor.

Claims (7)

[Claims] 1. A surveillance material, which is deteriorated to a degree lower than the expected deterioration of actual equipment, is mounted in the vicinity of an actual machine member of a nuclear power plant, and the deterioration degree of the surveillance material is detected by a magnetic signal or an electrical signal. Deterioration detection method characterized by estimating deterioration degree and replacement time of actual equipment by monitoring outside the plant with a database and comparing it with a database of strength characteristics and magnetic signals or electrical signals obtained in advance. . 2. A surveillance material which has deteriorated to a degree closer to the expected degree of deterioration of actual equipment in the vicinity of an actual nuclear power plant material, and a deterioration degree of the surveillance material which is monitored outside the plant and has strength characteristics which are obtained in advance. A sensor for detecting a magnetic signal or an electrical signal for estimating the deterioration degree and the replacement magnetism of the plant actual material by comparing with a database of the magnetic signal or the electrical signal, and the magnetic or electrical excitation. A deterioration detection sensor comprising a device. 3. The deterioration detecting method according to claim 1, wherein the sensor for monitoring the magnetic signal is a superconducting quantum interference device. 4. The deterioration detecting method according to claim 1, wherein the deterioration degree of the surveillance material is checked at every periodic inspection, and the deterioration degree of the plant actual material and the replacement time are estimated. 5. The deterioration detecting method according to claim 1, wherein the deterioration degree of the surveillance material is examined at every periodic inspection, and the deterioration degree of the plant actual material and the replacement time are estimated. 6. The deterioration detection sensor according to claim 2, wherein the deterioration degree of the surveillance material is checked at every periodic inspection, and the deterioration degree of the actual plant material and the replacement time are estimated. 7. A deterioration detecting sensor and method according to claim 1, 2, 3, 4, 5 or 6, wherein the deterioration event is irradiation embrittlement, aging embrittlement, and corrosion fatigue.