WO2022154634A1

WO2022154634A1 - Corrosion test apparatus

Info

Publication number: WO2022154634A1
Application number: PCT/KR2022/000898
Authority: WO
Inventors: 이유호; 황일순; 최재원
Original assignee: 서울대학교 산학협력단
Priority date: 2021-01-18
Filing date: 2022-01-18
Publication date: 2022-07-21

Abstract

The present invention relates to a corrosion test apparatus, the corrosion test apparatus according to the present invention comprising: a chamber accommodating a fluid; a disc on which a specimen is mounted and which is located in the fluid; and a driving unit which rotates the disc, wherein the specimen is arranged in the radial direction of the disc for a test of corrosion according to the relative flow velocity of the fluid, which continuously changes in the radial direction when the disc is rotating.

Description

corrosion test equipment

The present invention relates to a corrosion test apparatus, and more particularly, it is possible to test the corrosion of materials according to various flow rates of a fluid, and simultaneously control the flow rate of the fluid, the temperature of the fluid, and the concentration of oxygen in the fluid, and perform the corrosion test. It relates to a corrosion test apparatus that can be performed.

The most widely used nuclear reactor in the world is a pressurized light water reactor (PWR), which uses pressurized water to absorb energy from nuclear fuel rods and transmit it to a turbine to generate electricity.

On the other hand, a liquid metal cooling fast reactor refers to a reactor that uses sodium, lead, or lead-bismuth eutectic (LBE) as a coolant, unlike conventional reactors that use water as a coolant.

The fast reactor is a nuclear reactor that propagates nuclear fuel with a fast neutron, unlike a conventional nuclear reactor in which a nuclear fission reaction occurs with thermal neutrons. Unlike thermal neutrons, which fission only 0.7% of uranium-235 (ULSUP235) in nature, fast neutrons burn uranium-238 (ULSUP238), which exists in nature at a rate of 99.3%, into plutonium-239 (PLSUP239u). make it Therefore, it is known that the high-speed reactor consumes only a small amount of fuel, so that it has high thermal efficiency and economic feasibility, and high safety and nuclear proliferation resistance. In particular, since the risk of loss of coolant is low, the probability of serious accidents such as the Three Mile and Fukushima accidents is very low.

Furthermore, the lead-cooled fast reactor (LFR), which uses a lead-bismuth alloy as a coolant, has the advantage that compared to other types of fast reactors, the reactivity of the coolant is very low and the possibility of fire and explosion is significantly reduced due to its high boiling point. is being actively researched.

In addition to lead-cooled fast reactors, another type of next-generation reactor that compensates for the shortcomings of pressurized light reactors is the molten salt reactor (MSR). The molten salt reactor uses molten salt of a fluorine or chlorine compound as a coolant instead of water, and the molten salt has high chemical stability and high boiling point, so it is safe in operation and maintenance like a lead-cooled fast reactor. In addition, in this reactor, nuclear fuel can be melted and burned together with a coolant, which has the advantage of simplifying the reactor structure, making the combustion uniform, and facilitating the reprocessing of spent nuclear fuel.

However, both the lead-cooled fast reactor and the molten salt reactor are still in the early stages of development, and there are many fields that require research. In particular, liquid metals such as liquid lead and molten salt have not yet been used in the power generation industry, so research on how they affect the soundness of structural materials when flowing over them is insufficient.

One of the biggest challenges in the development of these next-generation reactors is that the materials that make up the reactors have to withstand temperatures and radiation damage that are two to three times higher than those of conventional reactors. For example, liquid lead-bismuth has a property of corroding components such as iron and nickel of the material it comes into contact with, but studies on how their flow rates affect corrosion are still lacking.

Corrosion studies by conventional liquid metals or molten salts are mainly conducted by immersing the specimen in lead in a stagnant state in a pool-type experimental device and observing the results, or using a loop equipped with a pump. In most cases, experiments were conducted by creating a flow of liquid metal using

The pool-type equipment that cannot make the flow rate is difficult to see as an actual nuclear reactor environment, and the loop-type equipment can observe the effect of the flow rate of liquid metal, but the scale is too large compared to the pull-type equipment, so the construction cost is high, and the It takes a lot of time and money to obtain experimental results, and has disadvantages in that it is difficult to control minute variables such as dissolved oxygen concentration.

Accordingly, an object of the present invention is to solve such a problem in the prior art, in which the specimen is arranged long in the radial direction of the disk rotating in the fluid, so that corrosion can be simultaneously tested under various flow rate conditions according to the radial position. To provide an experimental device.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The above object, according to the present invention, a chamber in which a fluid is accommodated; a disk for mounting the specimen and positioned within the fluid; and a driving unit for rotating the disk, wherein the specimen is disposed in a radial direction of the disk to inspect corrosion according to the relative flow rate of the fluid continuously changing in the radial direction when the disk rotates. can be achieved.

Here, the disk may be formed with a specimen holder that is elongated in the radial direction so that the specimen is inserted.

Here, a plurality of the specimen holder parts may be formed in a circumferential direction.

Here, the length in the circumferential direction of the specimen holder may be different from each other.

Here, the specimen may have a dog bone shape or a tube shape.

Here, the specimen holder may be coated with an insulating material.

Here, further comprising an autoclave accommodating the chamber, the temperature of the fluid may be controlled.

Here, it may further include an oxygen concentration control unit for controlling the concentration of oxygen in the chamber.

Here, the oxygen concentration control unit may include a gas supply line for supplying the oxygen concentration control gas into the chamber.

Here, the oxygen concentration control unit may control the concentration of oxygen by using a potential difference between the fluid and the thin film using an EOP (Electrochemical Oxygen Pumping) technology.

Here, the fluid may be any one of a liquid metal or a molten salt.

Here, the liquid metal may be any one of sodium, lead, lead-bismuth alloy, and lead-lithium alloy.

Here, the molten salt includes at least one of sodium, potassium, magnesium, lithium, beryllium, chlorine, and fluorine, and may contain a fissile material.

According to the corrosion test apparatus of the present invention as described above, there is an advantage that the corrosion test can be simultaneously performed under various flow rate conditions according to the radius by arranging and rotating the specimen in the radial direction of the disk.

In addition, it has the advantage of not being limited by the type of fluid because it can effectively generate various flow rates and perform corrosion tests even for fluids that are difficult to generate flow by using a pump because of their very high density or viscosity.

In addition, there is an advantage that the mechanical strength test can be performed after the corrosion test without going through a separate processing assumption for the specimen by manufacturing the specimen in the form of a dog bone.

1 is a cross-sectional view showing the configuration of a corrosion test apparatus according to an embodiment of the present invention.

Fig. 2 is a plan view of the disk of Fig. 1;

3 is a plan view showing a specimen according to the present invention.

4 is a view showing a state in which the specimen is fixed to the disk.

*Description of symbols*

110: chamber

115: autoclave

1151: heating means

120: disk

122: specimen holder part

124: screw hole

125: screw

130: driving unit

132: drive shaft

134: motor

140: gas supply line

142: control valve

150: temperature sensor

160: oxygen sensor

180: control unit

200: Psalm

P: fluid

The specific details of the embodiments are included in the detailed description and drawings.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, the present invention will be described with reference to the drawings for explaining the corrosion test apparatus according to the embodiments of the present invention.

1 is a cross-sectional view showing the configuration of a corrosion test apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the disk of FIG. 1, FIG. 3 is a plan view showing a specimen according to the present invention, FIG. 4 is It is a view showing a state in which the specimen is fixed to the disk.

A corrosion test apparatus according to an embodiment of the present invention may include a chamber 110 , a disk 120 , and a driving unit 130 .

The chamber 110 accommodates the fluid P. The present invention is an apparatus for accommodating the fluid (P) in the chamber (110) and testing the corrosion of the specimen (200) according to the flow rate of the fluid (P). It is known that the flow velocity of the fluid P, the temperature of the fluid P, and the concentration of oxygen in the fluid P are the causes of the greatest influence on the corrosion of the material in contact with the fluid P. As will be described later, in the present invention Corrosion test apparatus according to the flow rate of the fluid (P), as well as the temperature of the fluid (P), the oxygen concentration in the fluid (P) can be simultaneously controlled and the corrosion test can be performed.

In particular, the fluid P that can be used in the corrosion test in this embodiment may be a liquid metal used as a coolant in a liquid metal cooling fast reactor. For example, any one of sodium, lead, lead-bismuth alloy, and lead-lithium alloy may be used as the liquid metal. Therefore, it is possible to understand the effect of the flow rate of liquid metal on the corrosion of a nuclear reactor through a corrosion test.

In addition, the fluid P that can be used in the corrosion test in the present invention may be a molten salt used as a coolant of a molten salt reactor (MSR). In this case, the molten salt may include at least one of potassium, magnesium, lithium, beryllium, chlorine, and fluorine, and may contain a fissile material such as uranium or plutonium.

However, the fluid (P) used in the corrosion test apparatus according to the present invention is not limited to the liquid metal or molten salt, and it is corroded using any fluid (P) that is difficult to generate a direct flow due to its high density or high viscosity. experiments can be performed. Furthermore, the corrosion test apparatus according to the present invention has high versatility and can be used in corrosion tests using general fluids (P) such as water and organic compounds.

Since liquid metal may corrode the chamber 110 to reduce the device's health and reduce the reliability of the experiment, the chamber 110 is preferably formed of alumina or a metal crucible coated with an alumina material. do.

The chamber 110 may be accommodated in the autoclave 115 . The temperature of the liquid metal accommodated in the chamber 110 may be heated to a high temperature of 200° C. or more by the heating means 1151 of the autoclave 115, and the temperature may be controlled to an appropriate temperature. In addition, a temperature sensor 150 for measuring the temperature of the fluid P may be included.

Although not shown, the upper end of the chamber 110 and the autoclave 115 is formed to be separated by a separate cover so that it is sealed after accommodating the fluid P inside the chamber 110, so that external air or moisture to block the inflow.

In addition, since the concentration of oxygen dissolved in the liquid metal greatly affects corrosion of the metal material by the liquid metal, an oxygen concentration control unit for controlling the concentration of oxygen in the chamber 110 may be formed.

The oxygen concentration control unit may be a gas supply line 140 that supplies a gas for controlling the oxygen concentration into the chamber 110 . As an example of the oxygen concentration control gas, hydrogen gas may be used. Hydrogen supplied to the inside of the chamber 110 through the control valve 142 formed in the gas supply line 140 reacts with oxygen contained in the fluid P in the chamber 110 to increase the amount of oxygen dissolved in the fluid P. You can control the amount.

Alternatively, the amount of dissolved oxygen included in the fluid P may be controlled by using Electrochemical Oxygen Pumping (EOP) technology. The EOP method is a technique applied to control the concentration of oxygen dissolved in liquid LBE (lead-bismuth eutectic) or to produce high-purity oxygen. technology to control In the paper, "Control of dissolved oxygen in liquid LBE by electrochemical oxygen pumping, J.Lim", (https://www.sciencedirect.com/science/article/pii/S0925400514009575), the oxygen sensor and EOP are interlocked to dissolve in the medium. Since the description of the technology for controlling the oxygen concentration to be almost identical to the target value is disclosed, a detailed description of the EOP technology will be omitted.

At this time, when supplying hydrogen gas to the chamber 110 through the gas supply line 140, it is preferable to supply it mixed with an inert gas such as argon. This is because hydrogen can cause an explosive reaction in a high-temperature and high-pressure environment.

In addition, an oxygen sensor 160 including a Bi/Bi2O3 electrode is provided in the chamber 110 to measure the concentration of oxygen dissolved in the liquid metal.

The disk 120 may be formed as a circular disk, and the specimen 200 is mounted and rotated in the fluid P by the driving unit 130 . Therefore, in the present invention, a flow relative to the specimen 200 is formed by rotating the disk 120 within the fluid P, rather than forming a flow that is directly transmitted to the fluid P using a pump or the like. ), a corrosion test is performed according to the flow rate.

When the fluid P has high density or high viscosity, a very high energy is required to directly flow in the fluid P to obtain a meaningful level of flow velocity. However, as in the present invention, by rotating the disk 120 to which the specimen 200 is fixed to generate a relative flow, the corrosion test according to the flow rate is performed even when the density of the fluid P is high or the viscosity is high, such as liquid metal. can be done

In the present invention, the specimen 200 is elongated in the radial direction of the disk 120 . Even when the disk 120 rotates at the same angular speed, the circumferential speed increases according to the radial position, and the influence of the flow velocity on the specimen varies according to the radial position. Therefore, in the present invention, it is possible to continuously perform abrasion tests due to different relative flow rates in the radial direction by arranging the specimen 200 long in the radial direction. That is, as the single specimen 200 is continuously exposed to different flow rates according to positions, abrasion tests for various flow rates can be performed at once. The reactor material research takes about several thousand to ten thousand hours in one experiment, but the wear test apparatus according to the present invention can perform wear tests for various flow rates at once, so that the test time can be drastically reduced.

As shown in FIG. 2 , a specimen holder 122 , which is elongated in the radial direction, may be formed in the disk 120 . Accordingly, the specimen 200 long in the radial direction is inserted and fixed in the specimen holder part 122 .

A screw hole 124 into which a screw is inserted is formed in both radially outer portions of the specimen holder portion 122 . Therefore, as shown in FIG. 4 , after inserting the specimen 200 into the specimen holder portion 122 , the screw 125 is inserted into the screw hole 124 at a position close to the specimen holder portion 122 . The specimen 200 may be fixed to the disk 120 by supporting the specimen 200 by the head.

At this time, as illustrated, a plurality of specimen holder parts 122 may be disposed in a circumferential direction. Therefore, in the present invention, a corrosion test may be performed on a plurality of specimens 200 .

In addition, since the lengths in the circumferential direction of the specimen holder part 122 are different from each other, the specimens 200 of different sizes may be fixed to the disk 120 to perform a corrosion test at once.

In the drawings, only the specimen holder portion 122 elongated in the radial direction of the disk 120 is illustrated, but the present invention is not limited thereto and the specimen holder portion elongated in the tangential direction may also be formed. That is, not only the specimen holder part 122 formed long in the radial direction of the disk 120 but also the specimen holder part having a different direction or a different size or shape may be formed together, so that a corrosion test can be performed at the same time.

As shown in FIG. 3 , in the present invention, the specimen 200 is preferably formed to be elongated in one direction in the form of a dogbone-shaped plate. Accordingly, the shape of the specimen holder 122 may also be formed according to the shape of the dogbone. The shape of the specimen 200 is not limited thereto, and may be formed in the form of a long tube having a hollow therein.

As the specimen 200 has a long dogbone shape in one direction, a separate processing process for the specimen 200 after performing a corrosion test for the fluid P using the corrosion test apparatus according to the present invention A mechanical strength test (for example, a tensile strength test) of the specimen 200 may be immediately performed without it.

It is preferable that the specimen 200, the specimen holder part 122, and the screw for fixing the specimen 200 are made of the same material. This is because, when formed of different materials, an electrical potential is generated in the course of a corrosion test, which can affect corrosion. When it is difficult to manufacture the same material, it is preferable to coat the specimen holder 122 with an insulating material to block the electrochemical influence on the specimen 200 . In this case, when the corrosion test is performed on the specimens 200 of different materials, the influence by the electrical potential can be blocked.

The driving unit 130 rotates the disk 120 in the chamber 110 . The driving unit 130 is coupled to the center of the disk 120 to include a driving shaft 132 extending outside the chamber 110 and a motor 134 for rotating the driving shaft 132 outside the chamber 110 . can

The controller 180 receives the temperature of the fluid P inside the chamber 110 from the temperature sensor 150 , and receives the oxygen concentration in the fluid P from the oxygen sensor 160 , and controls the rotational speed of the motor 134 . Control of the relative speed of the fluid P through the control of the relative speed of the autoclave 115, the temperature control of the fluid P through the control of the heating means 1151 of the autoclave 115, and the opening and closing of the control valve 142 formed in the gas supply line 140 As a control, the oxygen concentration in the fluid P may be controlled by controlling the amount of hydrogen gas supplied into the chamber 110 .

Therefore, the corrosion test apparatus according to the present invention performs a corrosion test while simultaneously controlling the velocity of the fluid P, the temperature of the fluid P, and the concentration of oxygen in the fluid P, which are known factors that have the greatest influence on corrosion. can do.

The scope of the present invention is not limited to the above-described embodiments, but may be implemented in various forms within the scope of the appended claims. Without departing from the gist of the present invention claimed in the claims, it is considered to be within the scope of the claims of the present invention to the extent that various modifications can be made by anyone skilled in the art to which the invention pertains.

Claims

a chamber in which the fluid is received;

a disk for mounting the specimen and positioned within the fluid; and

It includes a driving unit for rotating the disk,

The specimen is disposed in the radial direction of the disk to test corrosion according to the relative flow rate of the fluid continuously changing in the radial direction when the disk rotates.
The method of claim 1,

Corrosion test apparatus in which a specimen holder part long in a radial direction is formed in the disk to insert the specimen.
3. The method of claim 2,

Corrosion test apparatus in which a plurality of specimen holder portions are formed in a circumferential direction.
4. The method of claim 3,

The length in the circumferential direction of the specimen holder is different from each other.
The method of claim 1,

The specimen is a dog bone (dog bone) shape or a tube (tube) shape of the corrosion test apparatus.
3. The method of claim 2,

The specimen holder portion is a corrosion test device that is coated with an insulating material.
The method of claim 1,

Further comprising an autoclave accommodating the chamber,

The temperature of the fluid is controlled corrosion test apparatus.
The method of claim 1,

Corrosion test apparatus further comprising an oxygen concentration control unit for controlling the concentration of oxygen in the chamber.
9. The method of claim 8,

The oxygen concentration control unit is a corrosion test apparatus including a gas supply line for supplying the oxygen concentration control gas into the chamber.
9. The method of claim 8,

The oxygen concentration control unit is a corrosion test apparatus for controlling the concentration of oxygen using the potential difference between the fluid and the thin film using EOP (Electrochemical Oxygen Pumping) technology.
The method of claim 1,

The fluid is any one of liquid metal or molten salt corrosion test apparatus.
12. The method of claim 11,

The liquid metal is any one of sodium, lead, lead-bismuth, and lead-lithium alloy.
12. The method of claim 11,

The molten salt includes at least one of sodium, potassium, magnesium, lithium, beryllium, chlorine, and fluorine, and a corrosion test apparatus containing a fissile material.