JP2000162369A - Neutron irradiation material inspection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly inspect a structure without gathering a sample by locally heating a material being subjected to neutron irradiation, and by directly analyzing a small amount of gas being discharged from a heating part for judging the content of He in the material. SOLUTION: A device body 8 is equipped with a water elimination mechanism, an argon gas inflow port, and a discharge port for discharging the mixture of the argon gas and a gas He being generated from a melting part. Heating is made by a high-frequency heating coil, and control is carried out by a current-controlling device 11. A current value is selected to become a temperature of 1,370-1,450 deg.C or more within the melting point range of stainless steel. Then, the relationship between heating time and the volume of the melting part are obtained. The discharge amount of He is divided by melting volume, and the concentration of He is obtained. The device body 8 is positioned in a material 1 to be measured so that the high-frequency heating coil is set to a measurement enforcement place, water in the device 8 is drained, and Ar gas 10 is allowed to flow. A part to be measured is heated by a specific current for specific time and is melted, and He being discharged from the melting part is allowed to flow to a gas analyzer 12 with the Ar gas for performing quantitative analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material inspection system for evaluating material properties of a material that has been irradiated with neutrons.

[0002]

2. Description of the Related Art Helium (He) is generated from boron (B), nickel (Ni), etc. by a transmutation reaction in materials of structures and equipment used in a neutron irradiation environment such as a nuclear power plant. I do. It is known that He causes micro-cracks in a heat-affected zone due to thermal processing such as welding to the structure or the device.

[0003] This is disclosed, for example, in the academic literature, "Welding Journal", pp. 33-39, published in 1988 (Weld. J., 1998, pp. 33-39).

It is known that the susceptibility of the micro-cracks depends on the He content of the material and the degree of heating during thermal processing. Therefore, knowing the He content in the material is useful for predicting, for example, the occurrence of micro-cracks due to thermal processing such as welding, and setting welding conditions that do not generate micro-cracks.

[0005] Conventionally, the measurement of the He content of the furnace internal structure has
A method of destructively cutting out a part of the furnace internal structure, sampling it as a sample, and measuring the He content by a mass spectrometer provided in a dedicated hot lab for separately analyzing radioactive materials. Had been. A method for diagnosing the weldability of the irradiated material using this technique has been proposed in Japanese Patent Application Laid-Open No. 7-244190. In this method, it is necessary to destructively take out a part of the structure of the nuclear reactor, and there is a problem that a special jig and a tool for sampling are required in addition to the evaluation of the structural integrity.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a neutron irradiation material inspection system which has conventionally required a sample to be obtained. A material inspection system is provided.

[0007]

According to the neutron irradiation material inspection system of the present invention, a neutron-irradiated material is locally heated, and a trace gas released from the heating section is directly analyzed to analyze the material. Is determined. Alternatively, a method is provided in which the He amount is determined from the presence or absence of cracking after the material is locally heated and cooled.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing an example of the configuration of a neutron irradiation material inspection apparatus using the He content determination method according to the present invention. Also,
FIG. 2 shows an enlarged view of the apparatus main body.

The material to be measured 1 is a structure in the reactor pressure vessel 2 and can be measured with the reactor water 3 in the pressure vessel 2. The power supply 9, the current control device 11, the Ar gas supply device 10, and the gas analysis device 12 are installed on the operation floor 6. FIG. 1 shows an example in which the material to be measured 1 is a shroud made of stainless steel.

The apparatus main body 8 has an opening 14 in contact with the material 1 to be measured, and the apparatus main body 8 is in close contact with the material 1 to be measured by the rubber packing 15, so that the airtightness in the container is maintained. ing. The apparatus main body 8 is large enough to pass through the upper lattice plate 4. A high frequency heating coil 19 that generates heat by electricity is installed in the container, and the current control device 11 can perform heating with a predetermined current and a predetermined time.

The apparatus main body 8 has a water removing mechanism 16, an inlet 17 for Ar gas 22 as a purge gas, and an outlet 18 for discharging a mixture 24 of Ar gas and gas (He) 23 generated from the melting portion. Have. The device body is
The drive unit connection section 20 is detachable by a drive mechanism and an electromagnet mechanism described below.

The driving device will be described. The driving device is shown in FIGS. First, 2 which has a telescopic mechanism in the core
The support pillar 30 having the next arm 31 is inserted. The support pillar 30 is large enough to pass through the upper lattice plate 4 and is connected to the support pillar drive robot 29 and its drive mechanism 28. In the state of FIG. 3, large swings occur between the upper lattice plate 4 and the lower core support plate 5. Can be restrained from occurring. The supporting pillar driving robot 29 and its driving mechanism 28, and the chamber driving mechanism 26 and the chamber driving robot 27 are connected to the crane 25.

Further, as shown in FIG.
Has an extension and contraction mechanism in a direction perpendicular to the support pillar 30, and the end of the arm can be combined with the apparatus main body 8 by an electromagnet mechanism. The slide mechanism 29 is detachably connected to the apparatus main body 8 by an electromagnet mechanism 33.

Next, the apparatus main body 8 is set on the inner surface of the shroud, which is the material 1 to be measured, by the chamber driving mechanism 26 (FIG. 3).

The heating device is heated by the high-frequency heating coil 19, and the heating temperature and the heating time are controlled by a constant voltage, a current and a time for flowing the current. The relationship between the current and the temperature is determined in advance using an optical pyrometer. As the current value, a current value at which the temperature is equal to or higher than 1370 to 1450 ° C., which is the melting point range of stainless steel, is selected. The volume of the melted portion is calculated by heating and melting a material that has not been irradiated with neutrons by using the apparatus main body 8, cooling, and then measuring the melted portion by observing a cross section to calculate the volume of the melted portion. As the heating time (current flowing time) and the temperature (current value) increase, the volume of the molten zone increases.
Find the relationship between the two.

The gas discharged from the outlet 18 is analyzed by the gas analyzer 12. The analytical method is qualitative and quantitative analysis of concentration using a mass spectrometer. Since all the He in the melted portion is released, the analysis result of He indicates that He
Release amount can be known. By dividing the amount of released He by the volume of the molten portion, the He concentration in the material to be measured can be obtained.

The gas analyzer 12 includes a pipe 7 for a ventilation air conditioning system or the like.
The gas after analysis is supplied to the ventilation and air conditioning system 1
It is processed in 3. When a different part is measured, the part is moved to a predetermined part by a driving device, and the He concentration is measured by a similar method.

FIG. 5 shows an example of a procedure of a neutron irradiation material inspection method using the He content determination method according to the present embodiment.

Step 3 of positioning the apparatus main body 8 on the material 1 to be measured so that the high-frequency heating coil 19 comes to the place where the measurement is performed.
After 5, the water in the apparatus is removed 36, and the process proceeds to a step 37 in which the Ar gas 22 is started to flow, and after a step 38 of heating the portion to be measured with a predetermined current and time, a step 39 of melting is performed.

He released from the molten portion of the material to be measured is represented by A
A step 40 of flowing He gas to the gas analyzer 12 and quantitatively analyzing He is performed. Step 41 for obtaining the volume of the fusion zone from the current and time is performed, and the process proceeds to Step 24 for calculating the He content (appm) from the quantitative analysis result of He and the volume of the fusion zone.

By performing the above steps, the He content can be calculated.

Embodiment 2 FIG. 6 is a diagram showing an example of the configuration of a neutron irradiation material inspection apparatus using the He content determination method according to the present invention. Also,
FIG. 7 shows an enlarged view of the apparatus main body.

The material 1 to be measured is a structure in the reactor pressure vessel 2 and can be measured with the reactor vessel 3 filled with the reactor water 3. The power supply 9, the current control device 11, the Ar gas supply device 10, and the gas analysis device 12 are installed on the operation floor 6. FIG. 6 shows an example in which the material to be measured 1 is a stainless steel shroud.

The apparatus main body 8 has an opening 14 in contact with the material 1 to be measured, and the apparatus main body 8 is in close contact with the material 1 to be measured by the rubber packing 15, so that the airtightness in the container is maintained. ing. The apparatus main body 8 is large enough to pass through the upper lattice plate 4. A high frequency heating coil 19 that generates heat by electricity is installed in the container, and the current control device 11 can perform heating with a predetermined current and a predetermined time.

The apparatus main body 8 has a water removal mechanism 16, an inlet 17 for Ar gas 22 as a purge gas, and an outlet 18 for discharging a mixture 24 of Ar gas and gas (He) 23 generated from the melting portion. Have. The device body is
The drive unit connection section 20 is detachable by a drive mechanism and an electromagnet mechanism described below.

A probe 47 for detecting a defect by a potential method is installed in the apparatus main body 8, and the probe is connected to a surface crack detection device 48 outside the container.

The driving device and the driving procedure are the same as in the first embodiment.

Further, the present apparatus uses a neutron irradiation material for calculating and evaluating from the information indicating the heating amount (temperature × time) of the apparatus for melting the surface and the crack initiation information of the surface crack detection apparatus near the melting portion. It has an inspection evaluation device 44.

FIG. 5 shows an example of a procedure of a neutron irradiation material inspection method using the He content determination method according to the present embodiment.

Step 3 of positioning the apparatus main body 8 on the material 1 to be measured so that the high-frequency heating coil 19 is located at the place where the measurement is performed.
After 5, the water in the apparatus is removed 36, and the process proceeds to a step 37 in which the Ar gas 22 is started to flow, and after a step 38 of heating the portion to be measured with a predetermined current and time, a step 39 of melting is performed.
At the time of the first heating, the material to be measured is heated for a very short time at a temperature substantially equal to the melting point of the material to be measured so as not to cause cracks.

After the melted portion has cooled 46, a step 47 of moving the apparatus main body 8 and installing the probe 45 on the melted portion 21 is performed. After the step 49 of evaluating the presence or absence of a crack by the surface crack detection device 43, if no crack has occurred,
Returning to the heating step 38, the process up to the evaluation 49 of the presence or absence of cracks is repeated again. At this time, the heating amount is increased stepwise with time as shown in FIG.

FIG. 10 shows the relationship between the He content and the amount of heating and the occurrence of cracks, which were previously experimentally obtained by using materials having various He contents. If a crack has occurred, the value of the heating amount at which the crack began to occur 53
From the He content 54 can be estimated. H of material
The amount of e is displayed on the neutron irradiation material inspection / evaluation device 44 for calculating and estimating from the information indicating the heat input amount of the device for locally melting the surface and the crack occurrence information of the surface crack detection device near the melting portion. Through the above steps, it was possible to determine the presence or absence of cracks with respect to the heat input of the irradiated material.

FIG. 11 shows a detailed configuration of the probe 47, the material to be measured 1, and the surface crack detecting device 41 for detecting a crack by the potential method in FIG. The principle of the potential method is to take out the resistance change due to the propagation of a crack as a change in voltage.
58 is attached, and a direct current is applied between the terminals 55 and 58. Further, the potential difference V between the terminals 56 and 57 is measured. This potential difference changes depending on the length of the crack, and the presence or absence of a crack and the length of the crack are determined by a master curve (FIG. 12) obtained from an experiment.

The measurement is performed in the data recording unit 60 controlled by the CPU 16. The data recording unit 60 controls the DC system power supply and the relay unit 62 to supply a DC current and measure a potential difference. The measured data is transferred to the CPU to perform data processing, and the processing result is transmitted to the neutron irradiation material inspection and evaluation device 44.

[0035]

According to the present invention, the He content of the material which has been irradiated with neutrons is determined, and / or the He content is determined based on the presence or absence of cracks after local heating and cooling.
By determining the amount, it became possible to non-destructively inspect the characteristics of the irradiated material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a neutron material inspection apparatus used in a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a main body of the neutron material inspection apparatus used in the first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a drive mechanism of the neutron material inspection device used in the first embodiment of the present invention.

FIG. 4 is a partially enlarged view of a drive mechanism of the neutron material inspection device used in the first embodiment of the present invention.

FIG. 5 is a flowchart showing a He content determination method according to the first embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a neutron material inspection apparatus used in a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a main body of a neutron material inspection apparatus used in a second embodiment of the present invention.

FIG. 8 is a flowchart showing a He content determination method according to a second embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a heating method according to the second embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a method for determining a He content from a heating amount at the time of occurrence of a crack in the second embodiment of the present invention.

FIG. 11 is a configuration diagram of a crack detection device by the potential difference method in FIG. 7;

FIG. 12 is a characteristic diagram illustrating crack detection by a potential difference method according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Material to be measured, 2 ... Pressure vessel, 3 ... Reactor water, 4 ... Upper lattice plate, 5 ... Core support plate, 6 ... Heating coil, 7 ... Ventilation air-conditioning piping, 8 ... Device body, 9 ... Power supply, 10 Ar gas supply device 11 Current control device 12 Gas analyzer 1
3: Ventilation air conditioning system treatment equipment, 14: Device opening, 15: Rubber packing, 16: Water elimination mechanism, 17: Gas inlet, 1
8 ... gas outlet, 19 ... high frequency heating coil, 20 ... drive unit connection part, 21 ... melting part, 22 ... Ar gas, 23 ... H
e gas, 24 ... Ar / He mixed gas, 25 ... crane,
26 ... chamber driving mechanism, 27 ... chamber driving robot, 28 ... support pillar driving mechanism, 29 ... support pillar driving robot, 30 ... support pillar, 31 ... secondary arm, 32
... drive mechanism operating device, 33 ... electromagnet mechanism, 34 ... slide mechanism, 35 ... installation of the device, 36 ... removal of water in the device,
37: Ar gas flow started, 38: heating, 39: melting, 4
0: Quantitative analysis of He amount, 41: Determination of volume of molten portion, 42
... Calculation of He content 43 Surface crack detector 44
Neutron irradiation material inspection / evaluation device, 45: probe, 46: cooling, 47: installation of probe, 48: crack initiation detection, 49:
Determination of the presence or absence of cracks, 50: Relationship between the presence or absence of cracks and heating amount at various He amounts, 51: Determination of He content, 52 ...
Indication, 53 ... Heating amount, 54 ... He content, 55-58 ...
Terminal: 59: DC system power supply, 60: Data recording unit, 61: CPU, 62: Relay unit, 63: Potential difference, 64: Crack length.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G21F 9/02 G21C 17/00 J (72) Inventor Takahiko Kato 3-1-1 Sachicho, Hitachi City, Ibaraki Prefecture No. Inside Hitachi Hitachi, Ltd. Hitachi Plant (72) Inventor Tomomi Nakamura 3-1-1 Sayukicho, Hitachi City, Hitachi City, Ibaraki F-term inside Hitachi Plant Hitachi Plant Co., Ltd. 2G075 AA03 BA18 CA07 DA07 DA09 EA03 EA07 FA04 FA20 FC01 FC13 GA00

Claims (12)

[Claims] 1. A neutron irradiation method for a material which has been subjected to neutron irradiation, wherein the material is locally heated and a trace gas released from the heated portion is directly analyzed to determine the He content in the material. Irradiation material inspection system. 2. The method according to claim 1, wherein the neutron-irradiated material is locally heated, and a trace gas released from the heated portion is directly analyzed to determine the He content in the material. Irradiation material inspection method. 3. The neutron irradiation material inspection system according to claim 1, wherein in the nuclear power plant, the gas after the trace gas analysis is processed into a radioactive substance by an exhaust gas treatment device such as a ventilation air conditioning system. 4. The neutron irradiation material inspection system according to claim 1, further comprising a radioactive substance removal filter before and / or after the trace gas analyzer. 5. The neutron irradiation material inspection system according to claim 1, wherein the trace gas analysis method is a gas chromatography method. 6. The neutron irradiation material inspection system according to claim 1, wherein the trace gas analysis method is a mass spectrometry method. 7. A neutron irradiation material inspection system characterized in that a neutron irradiation material inspection system is characterized by locally heating a neutron-irradiated material and judging the amount of He from the presence or absence of cracking after cooling of the heated portion. 8. A method for inspecting a neutron-irradiated material, the method comprising locally heating the material which has been irradiated with neutrons, and judging the amount of He from the presence or absence of cracks after cooling the heated portion. 9. The neutron irradiation material inspection system according to claim 6, wherein the amount of heat is increased stepwise at predetermined time intervals, and the occurrence of cracks is confirmed at each step. 10. The neutron irradiation material inspection system according to claim 6, wherein the heating method is heating by high frequency. 11. The neutron irradiation material according to claim 6, wherein the crack detection method is a potential method for forming an electric field by applying a current to a heated portion and detecting a shape of a defect based on how the electric field is disturbed. Inspection system. 12. An apparatus for locally melting a surface of a material irradiated with neutrons, an apparatus for processing gas emitted from a locally melted section, an apparatus for detecting a surface crack near a melted section, It is characterized by comprising a device for calculating and evaluating the He amount of the material from information indicating the heat input amount of the device for locally melting the surface and from crack occurrence information of the surface crack detection device near the melting portion. Neutron irradiation material inspection system.