KR102412794B1 - Measurement apparatus for determining cell size of nuclear fuel assembly spacer grid and Method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring the cell size of a spacer grid of a nuclear fuel assembly. It is a device and a measurement method that can accurately measure the cell size of a spacer grid with a simple structure while using the elasticity of the elastic part, including the configuration of the driving part.

Description

An apparatus for measuring the cell size of a nuclear fuel assembly spacer grid using elasticity and a measuring method using the same

The present invention relates to an apparatus for measuring the cell size of a spacer grid of a nuclear fuel assembly and a method for measuring the cell size using the same, and more particularly, to an apparatus for directly inserting a measuring apparatus into a cell of a spacer grid and measuring the cell size of the spacer grid using an elastic body and measurement methods.

In a nuclear fuel assembly, a spacer grid is a structure that supports fuel rods. As nuclear fuel combustion proceeds, fuel rods are disposed in a high-speed flow field of a nuclear reactor, and vibration and wear occur, and phenomena such as growth and warpage occur due to neutron irradiation. Whether the spacer grid stably supports the fuel rod under these conditions is a key factor influencing the soundness of nuclear fuel.

The cell size of the spacer grid affects the support performance of the fuel rod, and the cell size is defined as the distance between the spring located at the center height of the spacer grid cell and the dimples located at the upper and lower sides opposite to the spring. ) Since the fuel rod support performance gradually changes due to neutron irradiation during combustion of nuclear fuel, the cell size of the spacer grid is measured to determine this. By measuring the cell size of the spacer grid after combustion of nuclear fuel, characteristics such as soundness of fuel rods can be evaluated, and these characteristics are necessary for improving combustion performance.

The cell size of the spacer grid can be measured in the storage tank by using a separate instrument after removing the fuel rods from the nuclear fuel assembly. . However, it is not easy to transport radiated parts to the outside (ex. hot cell test facility), and it takes a lot of time, so it is difficult to reflect the measurement results in the design.

If it is not a hot cell test facility, it is not easy to measure the cell size of a space grid stored in a storage tank full of water, and there is no experience in measuring the cell size in a storage tank of a power plant in Korea. Therefore, it is necessary to improve the technology capable of accurately measuring the cell size of the space grid in a simple manner.

No. 10-1244865 (Registered on March 12, 2013)

The present invention relates to an apparatus for measuring the space lattice cell size of a nuclear fuel assembly and a measuring method using the same, which has improved the above-described problem, and to provide a technology capable of simply and precisely measuring the space lattice cell size of a nuclear fuel assembly stored in a storage tank. The purpose.

The present invention is an apparatus for measuring the cell size of a spacer grid, wherein a first contact portion that is inserted into a cell of the spacer grid and can contact a dimple of the spacer grid or a spring of the spacer grid is formed at a predetermined distance from the first contact portion, A second contact portion capable of contacting the dimple of the spacer grid or the spring of the spacer grid formed on the opposite side of the contact surface of the first contact portion is connected to the upper portion of the first contact portion and the second contact portion, the first contact portion and A driving unit for adjusting the interval of the second contact portion, an elastic portion having one end connected to the first contact portion and the other end connected to the second contact portion, and a guide formed to uniformly horizontally move the first contact portion or the second contact portion a displacement measuring unit for measuring a change in the distance between the first contact portion and the second contact portion, and a force applied to the first contact portion or the second contact portion to adjust the distance between the first contact portion and the second contact portion It includes a force measuring unit for measuring the size and a calculating unit for calculating the cell size of the spacer grid by using the value measured by the displacement measuring unit.

Preferably, the displacement measuring unit uses an LVDT (Linear Variable Differential Transformer) sensor.

Preferably, the guide part includes a guide pin provided in the first contact part or the second contact part, and a guide hole formed in the first contact part or the second contact part, and into which the guide pin is inserted.

Also, preferably, the elastic part is formed of a spring, and the guide pin is located inside the spring.

In addition, preferably, when the elastic part is compressed, a compression stopper protruding from the first contact part or the second contact part is further provided so that the distance between the first contact part and the second contact part does not become narrower than a predetermined distance. include

Also, preferably, the compression stopper is provided at a position of the guide hole, and the guide hole is formed to extend to the compression stopper.

In addition, preferably, when the elastic part is tensioned, it further includes a tension stopper that limits the distance between the first contact part and the second contact part not to be wider than a predetermined distance.

As a measuring method using the spacer grid cell size measuring device of the present invention, the first step of inserting the cell size measuring device into the cell, and the first contact part and the second contact part until the first contact part and the second contact part contact the spring and the dimple of the space grid. In the second step of stretching and when the first contact portion and the second contact portion contact the spring and dimple of the spacer grid, the third step of measuring the amount of change in the distance in the displacement measuring unit and the calculation unit from the width of the cell size measuring device and a fourth step of measuring the cell size of the space grid by calculating the amount of change.

According to the present invention, it is possible to measure the cell size in the storage tank without transferring the space grid to the hot cell test facility, saving a lot of time and effort compared to the prior art.

In addition, since the measurement time is reduced, feedback for design reflection is immediately possible, which has the effect of shortening the research time.

In addition, the simple configuration makes it easy to manufacture the device, while the risk of failure is low, and the use of a linear displacement transducer improves the accuracy of the measurement value.

1 shows a cross-section of a spacer lattice cell.
Figure 2 shows an apparatus for measuring the cell size of a space grid according to an embodiment of the present invention.
3 illustrates a process of measuring the cell size by inserting the cell size measuring device into the spacer cell.
Figure 4 is a graph showing the change in force according to the change in the spacing of the contact member in the cell size measurement process of Figure 3;
5 illustrates a cell size measurement process when the width of the cell size measuring device is larger than the cell size of the space grid.
6 is a graph showing the change in force according to the change in the spacing of the contact member in the process of measuring the cell size of FIG.

Specific structural or functional descriptions presented in the embodiments of the present invention are only exemplified for the purpose of describing embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention may be implemented in various forms. In addition, it should not be construed as being limited to the embodiments described herein, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Meanwhile, in the present invention, terms such as first and/or second may be used to describe various components, but the components are not limited to the terms. The above terms are used only for the purpose of distinguishing one component from other components, for example, within the scope not departing from the scope of the rights according to the concept of the present invention, the first component may be named as the second component, Similarly, the second component may also be referred to as a first component.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

Hereinafter, the present invention will be described with reference to the accompanying drawings. In the description of the present invention, when it is determined that the description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the description thereof is omitted.

2 and 3, the cell size measuring apparatus 100 according to an embodiment of the present invention and the state of measuring the cell size using the same are shown. The cell size measuring device 100 includes a first contact portion 110 and a second contact portion 120 (hereinafter referred to as a “contact member”) capable of contacting the space grid dimple 12 or the spring 11 . . In addition, it includes a driving unit 190 for adjusting the distance between the contact members and an elastic unit 130 positioned between the contact members. And, it includes a guide part for guiding the movement of the contact member, a displacement measuring part 160 for measuring a change in the distance between the contact members, and a force measuring part 170 for measuring the force acting on the contact member. In addition, it may include a calculator 180 that calculates the cell size of the space grid by using the measured value of the displacement measuring unit 150 or the force measuring unit 170 .

The first contact portion 110 may contact the dimple 12 of the spacer grid or the spring 11 of the spacer grid. The second contact portion 120 is formed parallel to the first contact portion 110 at a predetermined distance, and the dimple 12 of the spacer grid or the spring ( 11) is in contact.

The driving unit 190 is connected to the upper portions of the first contact unit 110 and the second contact unit 120 , and is a means for adjusting the distance between the first contact unit 110 and the second contact unit 120 . The driving unit 190 may horizontally move the first contact unit 110 or the second contact unit 120 as a mechanical component that can be operated remotely. A known technology that satisfies the above-described function by a person skilled in the art may be applied to the driving unit 190 .

The elastic part 130 is an elastic object having one end connected to the first contact part 110 and the other end connected to the second contact part 120 , and is positioned between the contact members. Accordingly, an elastic force acts when the distance between the first contact part 110 and the second contact part 120 is adjusted, and the elastic part 130 may include a spring or other elastic member.

The guide part is a means for guiding the first contact part 110 or the second contact part 120 to uniformly horizontally move when the distance between the first contact part 110 and the second contact part 120 is adjusted in the driving part 190 . The guide part may include a guide pin 141 provided horizontally to the first contact part 110 or the second contact part 120 and a guide hole 142 formed to insert the guide pin 141 . Preferably, the guide pin 141 is positioned in the spring of the elastic part 130 so that the cell size measuring device 100 has a simple structure.

The guide pin 141 moves inside the guide hole 142 to guide the horizontal movement of the first contact part 110 or the second contact part 120 . However, the guide method is not limited to the above-described configuration, and other known guide methods applicable to those skilled in the art may be used.

The displacement measuring unit 160 is a means for measuring a change in the interval between the first contacting part 110 and the second contacting part 120 . A scale may be displayed or a sensor may be used to quantitatively check the interval change. The sensor preferably uses a linear variable differential transformer (LVDT). The displacement measuring unit 160 is connected to the driving unit 190 or the contact member, and may be appropriately applied by a person skilled in the art according to a measuring method or a sensor type.

The force measuring unit 170 measures the force applied to the first contact unit 110 or the second contact unit 120 by the driving unit 190 to adjust the distance between the first contact unit 110 and the second contact unit 120 . is a means It is possible to measure the force applied to the contact member by the driving unit 190 in real time by providing a sensor (load cell, strain gauge, etc.) necessary for measuring the force. By the force measuring unit 170, it is possible to observe the change in the force according to the change in the contact member spacing or the change in the force according to the passage of time.

The force applied to the contact member by the driving unit 190 will increase or decrease at a certain inclination according to the spacing between the contact members due to the elastic force of the elastic unit 130 . However, when the contact member comes into contact with the spring 11 or the dimple 12, the elastic force of the spring 11 or the dimple 12 also acts to change the inclination of the force according to the spacing between the contact members.

Accordingly, it can be confirmed that the contact member is in contact with the spring 11 or the dimple 12 at the time the inclination of the force changes. The force measuring unit 170 is connected to the driving unit 190 or the contact member, and may be appropriately provided according to the measuring method or the type of the sensor.

The calculating unit 180 is configured to calculate the cell size of the spacer grid by using the value measured by the displacement measuring unit 160 or the force measuring unit 170 . The cell size of the spacer grid is calculated by subtracting or adding the displacement measured by the displacement measuring unit 160 to the initial width of the cell size measuring device 100 when the contact member contacts the spring 11 and the dimple 12 . can do.

Referring to FIG. 2 , the tension stopper 152 is configured to limit the distance between the first contact part 110 and the second contact part 120 so as not to exceed a predetermined distance.

One end of the tension stopper 152 may be fixed to any one of the contact members, and the other end may pass through the other contact member. The other end of the tension stopper 152 is formed to be larger than the through hole so as not to fall out from the penetrating contact member. Therefore, although it is possible to narrow the spacing of the contact members, widening beyond a certain range is limited. This is because the other end of the tension stopper 152 cannot escape through the through hole. The contact member may have a groove 153 in a portion where the other end of the tension stopper 152 is located.

The extension guide 151 is configured to prevent the guide pin 141 from being separated from the guide hole 142 when the distance between the contact members increases. The extension guide 151 is positioned where the guide hole 142 is formed, and extends the guide section so that the guide pin 141 does not separate.

)이 지지격자의 셀크기보다 작은 경우에 셀크기를 측정하는 모습과 접촉부재의 간격 변화에 따른 힘의 변화를 도시한다.3 and 4, the initial width of the cell size measuring device 100 (

) is smaller than the cell size of the spacer grid, the cell size is measured and the change in force according to the change in the spacing of the contact member is shown.

In FIG. 3 , the initial position of the second contact unit 120 is represented by a dotted line based on the state in which the first contact unit 110 is in contact with the dimple 12 , and in this case, the initial width of the cell size measuring device 100 is l is ₁ . In addition, the moment the second contact part 120 touches the spring 11 by widening the gap between the first contact part 110 and the second contact part 120 is expressed by a solid line.

The displacement moved from the initial state until the second contact part 120 comes into contact with the spring 11 is X ₁ . Thereafter, the second contact part 120 may move finely while receiving the resistance of the spring 11 or the dimple 12 to finally cause displacement by X ₂ .

FIG. 4 shows the magnitude of the force measured by the force measuring unit 170 according to the change in the spacing of the contact members in FIG. 3 . As the distance between the contact members increases, the elastic force of the elastic part 130 increases, and the force applied to the contact member by the driving part 190 increases linearly. And, after the contact member contacts the spring 11 and the dimple 12, the resistance of the spring 11 and the dimple 12 is added, so that the inclination of the force according to the displacement becomes larger. That is, the inclination of the force increases after the interval between the contact members is increased by X ₁ in FIG. 3 . At this time, the point at which the inclination of the force changes is the point at which the contact member contacts the spring 11 and the dimple 12 . Therefore, the cell size of the spacer lattice can be calculated using the displacement (X ₁ ) at the time point, and the formula is as follows.

[Equation 1]

W = l ₁ + X ₁

W: cell size of spacer grid

l ₁ : Initial width of cell size measuring device

X ₁ : Displacement increased until the gap of the contact member contacts the spring

)이 지지격자의 셀크기보다 큰 경우에 셀크기를 측정하는 모습과 접촉부재의 간격 변화에 따른 힘의 변화를 도시한다.5 and 6, the initial width of the cell size measuring device 100 (

) is larger than the cell size of the spacer grid, the cell size is measured and the change in force according to the change in the spacing of the contact member is shown.

In FIG. 5 , the initial position of the second contact portion 120 based on the state in which the first contact portion 110 is in contact with the dimple 12 is represented by the outermost (right) dotted line. In addition, when the interval of the contact member is compressed by X ₃ to insert the measuring device 100 into the cell, the position is shown by the inner (left) dotted line. The size of X ₃ is sufficient as long as the measuring device 100 can be inserted into the cell.

FIG. 6 shows the magnitude of the force measured by the force measuring unit 170 according to the change in the spacing of the contact members in FIG. 5 . Starting from a state in which the gap between the contact members is reduced by X ₃ , the gap between the contact members is widened until the second contact part 120 comes into contact with the spring 11 . Since the elastic part 130 returns to its original state in a compressed state, the elastic force acting as the gap between the contact members is widened is reduced. Accordingly, the magnitude of the force measured by the force measuring unit 170 as shown in FIG. 6 is gradually reduced.

In a compressed state, the contact member is spread by X ₄ to contact the spring 11 , and moves finely while receiving resistance of the spring 11 and the dimple 12 , and finally displacement by X ₅ may occur. At this time, the displacement (X ₄ ) at the time the inclination of the force changes can be known through the force measuring unit 170 and the displacement measuring unit 160 , and the cell size of the spacer grid can be calculated using this. The expression is:

[Equation 2]

W= l ₂ - X ₃ + X ₄

W: cell size of spacer grid

l ₂ : Initial width of cell size measuring device

X ₃ : Displacement by compressing the gap of the contact member

X ₄ : Displacement increased until the gap of the contact member contacts the spring

Hereinafter, a method for measuring the cell size of the spacer grid using the cell size measuring apparatus 100 will be described.

First, the cell size measuring device 100 is inserted into the cell. The cell size measuring device 100 may be inserted into the spacer grid cells located in the storage tank using a remotely operable mechanical device. In addition, it is also possible to compress the cell size measuring device 100 according to the width of the cell size measuring device 100 and then inserting it into the cell.

Then, the gap is increased until the first contact portion 110 and the second contact portion 120 come into contact with the spring 11 and the dimple 12 of the spacer grid. At this time, the force measuring unit 170 and the displacement measuring unit 160 measure the force applied to the contact member and the change in the spacing between the contact members. ( X ₁ , X ₃ , X ₄ , etc.)

When the first contact part 110 and the second contact part 120 come into contact with the spring 11 and the dimple 12 of the spacer grid, the displacement of the gap is measured, and the cell size of the spacer grid is calculated using the measured value. (Refer to Equations 1 and 2) At this time, the cell size of the spacer grid is obtained using the measured value at the point where the slope of the force according to the displacement changes.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and it will be apparent to those skilled in the art that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention.

10: spacer cell
11: spring
12: dimple
100: cell size measuring device according to an embodiment of the present invention
110: first contact portion
120: second contact portion
130: elastic part
141: guide pin
142: guide hole
151: extension guide
152: tension stopper
153: home
160: displacement measuring unit
170: force measurement unit
180: arithmetic unit
190: driving unit

Claims (7)

a first contact part which is inserted into the cell of the spacer grid and can contact the dimples of the spacer grid or the spring of the spacer grid;
a second contact portion formed at a predetermined distance from the first contact portion and capable of contacting the dimple of the spacer grid or the spring of the spacer grid formed on the opposite side of the surface in contact with the first contact portion;
a driving unit connected to upper portions of the first contact portion and the second contact portion and adjusting a distance between the first contact portion and the second contact portion;
an elastic part having one end connected to the first contact part and the other end connected to the second contact part;
The first contact portion or the second contact portion is constant, including a guide pin provided in the first contact portion or the second contact portion, and a guide hole formed in the first contact portion or the second contact portion and into which the guide pin is inserted. a guide unit provided for horizontal movement;
a displacement measuring unit capable of measuring a change in a distance between the first contact part and the second contact part;
a force measuring unit capable of measuring a magnitude of a force applied to the first contacting portion or the second contacting portion in order to adjust a distance between the first contacting portion and the second contacting portion; and,
It includes; a calculation unit for calculating the cell size of the space grid using the value measured by the displacement measuring unit;
and an extension guide extending a guide section from a position of the guide hole so that the guide pin does not deviate from the guide hole when the elastic part is tensioned. According to claim 1,
Displacement measuring unit,
A cell size measuring device of a space grid, characterized in that it uses a LVDT (Linear Variable Differential Transformer) sensor. delete According to claim 1,
The elastic part is formed of a spring, and the cell size measuring device of the spacer grid, characterized in that the guide pin is located inside the spring. delete According to claim 1,
When the elastic part is tensioned, the cell size measuring device of the spacer grid further comprising a tension stopper that limits the distance between the first contact part and the second contact part not to be wider than a predetermined distance. In the method for measuring the cell size of a space grid using the cell size measuring device of claim 6,
A first step of inserting the cell size measuring device into the cell;
a second step of increasing the distance between the first contact portion and the second contact portion until they contact the springs and dimples of the spacer grid;
a third step of measuring a change in the distance in a displacement measuring unit when the first contact portion and the second contact portion contact the spring and the dimple of the spacer grid; and
A fourth step of measuring the cell size of the space lattice by calculating the value measured in the third step from the width of the cell size measuring device in the calculation unit;

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