JPH04294242A - Nondestructive inspection of diverter plate - Google Patents

Abstract

PURPOSE:To inspect a joint of a diverter plate nondestructively at a low cost during manufacturing or service of the diverter plate placed in a fusion reactor. CONSTITUTION:A baking system 3 or the like is utilized to heat a diverter plate 1 from a side of a cooling member, a rate of temperature rising on a surface inside a reactor of a protection tile 3 which rises in temperature due to the heat transmitted from the cooling member through a brazed joint surface to the protection tile 3 is measured by a radiation thermometer 2 or the like, and change in a joining state of the brazed joint is sensed based on the measurement results or the protection tile failing is specified.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for non-destructive inspection of a diverter plate installed in a nuclear fusion reactor during manufacture or during use.

0002

BACKGROUND OF THE INVENTION The structure of a divertor plate is to form a protective tile made of carbon material such as a carbon composite material and directly braze it to a cooling pipe 32 as shown in FIG. A structure in which brazing is performed via the copper block 33 is considered to be promising.

[0003] Although the diverter plate is constantly subjected to a high heat flux of 10 MW/m2 or more and its temperature rises, it is required that the surface temperature of the protective tile be suppressed to about 1000°C or less. Therefore, it is necessary to maintain a good bonding state of the brazed portion between the carbon material protective tile and the copper cooling pipe, or between the carbon material protective tile and the copper block, so as to sufficiently reduce the thermal resistance of the bonded portion. Conventionally, the method of inspecting this bonding state during manufacturing and/or during service is
Destructive inspection methods ■ Inspection methods using ultrasonic flaw detection and other methods have been studied.

0004

[Problems to be Solved by the Invention] However, each of the above conventional methods has the following drawbacks.

First, in the destructive testing method, (1) It is actually impossible to completely destroy the diverter plate itself after it has been completed as a product to inspect the joint state. ■
When a bonded part changes due to thermal cycling during service and a defect occurs, it is difficult to discover it or specify its location.

Furthermore, in the ultrasonic flaw detection method, (1) Carbon materials have large attenuation of ultrasonic waves, resulting in very poor detection sensitivity. ■ Carbon materials (carbon composites) are non-homogeneous and porous materials, which causes diffuse reflection of ultrasonic waves, making detection difficult. ■To perform inspections during service, the procedure is extremely complicated, as a detector must be brought into the reactor, which is a radiation field, by remote control and measured by touching the surface of the divertor plate.

[0007] The present invention solves these problems, and by using a simple configuration and low equipment cost, the state of the joint between the protective tile of the diverter plate and the cooling pipe or cooling block can be changed during manufacturing or during service. The purpose is to provide a destructive and accurate inspection method.

[0008]

The above object is achieved by a method for non-destructive testing of a diverter plate as set forth in the claims. That is, a diverter plate installed in a nuclear fusion reactor that has a structure in which a protective tile made of carbon-based material and a copper cooling pipe is penetrated and bonded to the protective tile, or a protective tile made of carbon-based material and a cooling block made of copper. In the diverter plate having a structure in which the protective tiles are joined together, the protective tiles are heated from the side of the cooling pipe or the cooling block, the rate of temperature rise of each heated protected tile is measured using a radiation thermometer, etc., and the joining process is performed based on the measurement results. This is a non-destructive testing method for divertor plates that inspects the joint state of parts.

The effects of the present invention will be explained below based on examples.

0010

[Embodiment] The diverter plate is used when a copper cooling pipe (hereinafter referred to as a copper pipe) 32 is inserted into the protective tile 31 shown in FIG. 4 and joined by brazing, or when the protective tile 3
1 and a copper block (hereinafter referred to as the copper block) 33, a protective tile 31 made of carbon-based material having a surface area of about 30 mm square and a thickness of about 10 mm is installed inside the furnace. By brazing the back side of the protective tile 31 with the copper pipe 32 or copper block 33 and letting cooling water pass through the copper pipe 32 or the copper block 33, the surface temperature of the protective tile 31 can be raised to 1000°C. It is kept below.

[0011] The protective tile 31 and the copper tube 32 or the copper block 33 are usually bonded by vacuum brazing, but in rare cases, complete bonding may not be achieved. Furthermore, during the operation of a nuclear fusion reactor, there is a possibility that the joint between the protective tile made of carbon material and the cooling part 31 made of copper may peel off due to the difference in thermal expansion between them due to repeated thermal cycles.

FIG. 1 is a diagram showing a schematic system of a method for non-destructively testing the junction between the protective tile of the diverter plate and the copper cooling part according to the present invention, in which 1 is a diverter plate, 2 is a thermometer, 3 is a baking system, 4 is a heater, 5 is a circulation pump, 6 is a cooler, and 7 to 10 are stop valves.

When the fusion reactor is in service, the stop valve 7 and the stop valve 8 shown in FIG. 1 are opened, and the stop valve 9 and the stop valve 10 are closed to form a cooling system for the diverter plate 1. In other words, the low-temperature cooling water discharged from the circulation pump 5 flows into the divertor plate 1, cools the divertor plate whose temperature has increased due to the high heat flux from the plasma side, and raises its own temperature, causing the cooling water to flow into the divertor plate 1. Enter within 6. The cooling water, whose temperature has been lowered by heat exchange with another medium in the cooler 6, is again pressurized by the circulation pump 5 and sent to the diverter plate 1.

On the other hand, while a nuclear fusion reactor is in service, it is necessary to maintain a high degree of vacuum inside the reactor. Therefore, when installing the diverter plate 1, the diverter plate 1 is heated to about 200 to 300°C using high-temperature gas or hot water to purge the gas remaining on the surface. The baking system 3 is configured by closing the valve 8 and opening the stop valves 9 and 10, and the cooling water in the loop is circulated while being heated by the heater 4, thereby increasing the temperature of the diverter plate 1.
It has been considered to heat the gas and purge the above gas, etc.

When inspecting the joints of the diverter plate 1 according to the present invention, the cooling system for the diverter plate 1 is first switched to the baking system 3 described above. Next, the circulation pump 5 is driven to circulate the cooling water within the system, while the heater 4 is operated to raise the temperature of the circulating cooling water. Accordingly, heat is transferred from the cooling member side to the protective tile 31 side of the diverter plate 1, and the temperature of the furnace inner surface of the protective tile 31 increases.

At the same time, a thermometer 2 such as a radiation type is installed inside the furnace.
The diverter plate 1 is held and disposed so as to be movable and swingable by a robot or the like so that the surface temperature of all the diverter plates 1 can be measured.

[0017] When the protective tile 31 and the cooling member are sufficiently bonded, the surface temperature of the protective tile 31 increases almost uniformly, but some parts of the bonded portion are peeled off. In this case, heat transfer in that area is inhibited, and the rate of increase in the surface temperature of the protective tile 31 is reduced. However, even in that case, by continuing heating from the cooling member side for a long time, the surface temperature of all the protective tiles 31 will eventually become approximately uniform.

Therefore, in the present invention, the rate of increase in surface temperature of the protective tile 31 at the initial stage of heating, which causes a difference in rate of temperature increase depending on the condition of the bonding members described above, is detected, and the rate of increase in temperature is measured in advance before inspection. The state of the joint is determined by comparing the previously prepared joint state with the data on the rate of temperature rise, and whether the protective tile 31 is sufficiently sound or within an acceptable range where some peeling is observed but is still sufficiently safe. Is it in
Alternatively, it determines whether immediate replacement is required.

In the case of a structure in which the protective tile 31 is divided into small blocks as described above, the soundness of the diverter plate 1 can be confirmed with sufficient accuracy by identifying the defective protective tile 31 according to the method prescribed in the regulations. It is possible to do this.

When heating the diverter plate 1, high-temperature gas or electrical heating may be used in addition to the above-mentioned heating by the baking system, and the protective tile 31 whose temperature has been raised by heating from the cooling member side may be used. Of course, a contact measuring device such as a thermocouple can be used to measure the surface temperature.

Prior to filing the application, the inventors of the present application experimentally confirmed how the state of heat transfer differs depending on the joint state of the brazed joint between the protective tile of the diverter plate and the cooling member. , the results are explained below.

(1) Experimental method The test piece used in this experiment was made of copper (oxygen-free copper) and carbon-based material (
CX-2002U) brazing test pieces, each vertically 2
It has dimensions of 1 mm x width 23 mm x thickness 10 mm. A copper test piece was placed at the bottom, a carbon material test piece was placed at the top, a release agent (boron nitride) was partially applied to the bonding interface, and the test pieces with different bonding rates were No. 1, No. I made 2 pieces. The bonding rate of each test piece was No. 1 to about 45%
, No. 2 was about 80%.

As shown in FIG. 2, the test was carried out by placing two test pieces 22, 2 on a steel block (heat source) 21 heated to about 60°C.
3 were placed side by side with the copper facing down, and observation was made with an infrared camera 24 from the carbon material side, which is the side opposite to the heating surface. As a result, changes in the surface temperature of the carbon material due to heat transfer occurring in a direction perpendicular to the brazed joint interface 25 from the copper side were observed. The infrared observation device used was 3.0 to 5.
It is possible to observe infrared rays of 4 μm, and 20
A device that can capture images and has a maximum temperature resolution of 0.1° C. was used.

(2) Experimental Results ■ Approximately 3 seconds after the start of the test, the surface temperature of the carbon material test piece on the infrared camera 24 side reached No. 1 test piece 22 at about 20°C,
No. 2 test piece 23 was at about 25°C. (2) Figure 3 shows the temperature change of each test piece, with the horizontal axis showing time (1 scale: 10 seconds) and the vertical axis showing temperature (0°C to 40°C). As is clear from the figure, the temperature rise rate was different for the two test pieces, and No. 1 test piece 22 is approximately 0.85℃
/second (curve 22' in the figure), No. 2 test piece 23 is about 1.4° C./sec (curve 23' in the figure), and it can be seen that the higher the bonding rate, the faster the temperature rise. The above two test pieces with different bonding rates were heated from the copper side and observed from the opposite carbon material side. As a result, the rate of temperature rise differs depending on the bonding rate, and the higher the bonding rate, the higher the temperature. was confirmed to be fast.

[0025]

[Effects of the Invention] According to the present invention, as described in the above embodiments, the following effects are achieved. ■
It is possible to easily and non-destructively inspect the joint state of protective tiles during the manufacture of diverter plates. ■ It is possible to easily and non-destructively inspect the bonding condition of the protective tiles of the diverter plate in service. ■
For inspections during service, the diverter plate can be heated using a baking system, so there is no need to install new special equipment.
Can be implemented at low cost. ■ By comparing the temperature rise rate of the same protective tile during service with the value from the previous inspection, it becomes possible to easily determine changes in the bonding state due to operation. ■ Temperature detection can be performed using a remote device such as a radiation thermometer, so it can be carried out in an extremely simple procedure. ■ It is possible to perform measurements without depending on the material, structure, etc. of the protective tile.

[0026]

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic system of a method for non-destructive testing of a diverter plate according to the present invention.

FIG. 2 is a diagram showing an outline of an experiment conducted by the inventors of the present application.

FIG. 3 is a diagram showing experimental results.

FIG. 4 is a partial perspective view of a diverter plate in which a protective tile and a copper tube are directly brazed.

FIG. 5 is a partial perspective view of a diverter plate to which protective tiles are joined via a copper block.

[Explanation of symbols]

1 Diverter plate 2 Thermometer 3 Baking system 4 Heater 5 Circulation pump 6 Cooler 7 Stop valve 8 Stop valve 9 Stop valve 10 Stop valve 21 Heat source 22 No. 1 test piece 22'No. Temperature curve of 1 test piece 23 No. 2 test pieces 23'No. Temperature curve of 2 test pieces 24 Infrared camera 25 Brazed joint interface 31 Protective tiles 32 Copper tube 33 Copper block

Claims (1)

[Claims] Claim 1: A diverter plate installed in a nuclear fusion reactor, which has a structure in which a protective tile made of a carbon-based material and a cooling pipe made of copper is penetrated and bonded to the protective tile, or a protective tile made of a carbon-based material and a copper cooling pipe. In the diverter plate, which has a structure in which a cooling block is joined to the protective tile, the protective tile is heated from the cooling pipe or cooling block side, the rate of temperature rise of each heated protective tile is measured using a radiation thermometer, etc., and the measurement results are 1. A method for non-destructive testing of a diverter plate, characterized in that the joint state of a joint is inspected based on the method.