KR101620630B1 - Loading monitoring system for spent nuclear fuel and method thereof - Google Patents

Abstract

An optical fiber that is exposed to radiation and converts the radiation into light and transmits the light; An optical sensor for converting the light transmitted through the optical fiber into an electric signal to generate an electric signal; And a server for calculating storage information of the spent nuclear fuel by calculating the electric signal by using a radiation intensity graph, wherein the server is a server for storing spent fuel in a basket unit, A reference graph storing unit storing a reference graph which varies according to the number of the reference graph; A comparator for converting the electrical signal generated by the optical sensor into a radiation intensity graph and comparing the electrical signal with the reference graph; And an arithmetic unit operable to calculate a comparison value in the comparison unit to determine storage information of the spent nuclear fuel.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel loading diagnostic system,

The present invention relates to a system and a method for diagnosing a spent nuclear fuel loading, and more particularly, to a system and a method for diagnosing a spent nuclear fuel loading using an optical fiber to check the progress of loading and completion of loading of spent nuclear fuel.

As interest in energy has increased recently, interest in nuclear power generation is increasing. However, due to the danger of spent fuel inevitably produced in nuclear power generation process, post management has been a problem. Spent fuel is a lethal substance in the human body. Even if it is exposed only a little, it threatens the life of the human body and greatly pollutes the environment. Therefore, thorough management supervision is required.

Fig. 1 is a view showing a reservoir for storing spent fuel. The storage 10 may store 40 storage cylinders 40 in which the spent nuclear fuel 20 is stored. Each storage cylinder 40 can accommodate 10 spent fuel baskets 30. Such a reservoir 10 has a method in which the basket 30 containing spent fuel 20 is stored in the storage cylinder 40 so as to seal the inlet of the storage cylinder 40 and prohibit the discharge. Therefore, after storing the basket 30 in the storage cylinder 40 once, there is a problem that the basket 30 is simply left or is temporarily checked for the leakage of the radioactive material. This is a problem that occurs because the reservoir 10 can not perform other functions other than shielding the spent nuclear fuel 20.

An embodiment of the present invention is to propose a post-use fuel loading diagnostic system and method for confirming whether a sealed container containing spent fuel or spent nuclear fuel is loaded and after the completion of loading.

An optical fiber which is exposed to radiation and converts the radiation into light and transmits the light; An optical sensor for converting the light transmitted through the optical fiber into an electric signal to generate an electric signal; And a server for calculating storage information of the spent nuclear fuel by calculating the electric signal by using a radiation intensity graph, wherein the server is a server for storing spent fuel in a basket unit, A reference graph storing unit storing a reference graph which varies according to the number of the reference graph; A comparison unit for converting the electrical signal generated by the optical sensor into a radiation intensity graph and comparing the electrical signal with the reference graph, and a computing unit for computing the stored information of the spent nuclear fuel by calculating a comparison value in the comparison unit. It provides a fuel loading diagnostic system.

According to an embodiment of the present invention, the optical fiber may be arranged such that the spent fuel is linearly extended so as to be inserted into a storage container accommodated in a basket.

According to an embodiment of the present invention, the radiation may be a gamma ray.

According to an embodiment of the present invention, the reference graph has a stepped waveform having an ascending or descending waveform, the stepped waveform having the same number of rectangular waveforms as the number of baskets of the spent nuclear fuel, Is divided into a horizontal portion and a wave portion, and the wave portion may have an exponential waveform that rises or falls.

According to an embodiment of the present invention, the optical sensor includes a photodetector, and the photodetector may be a charge-coupled device (CCD), a photodiode, or a photomultiplier tube (PMT) .

According to an embodiment of the present invention, the storage information includes at least one of a carry-in information of the spent fuel, a carry-out information of the spent fuel, a loading process information of the spent fuel, a basket loading completion information of the spent fuel, And information on the number of baskets of the spent nuclear fuel.

According to an embodiment of the present invention, there is provided a method of detecting radiation, comprising the steps of: detecting radiation using an optical fiber, Converting the transmitted light into an electrical signal and transmitting the electrical signal; Calculating the transmitted electrical signal with a radiation intensity graph; Generating and preparing a reference graph; Comparing the radiation intensity graph and the reference graph; And determining the state of the spent fuel stored in units of baskets using the comparison result, wherein the reference graph has a stepped waveform having a rising or falling step, Wherein each of the rectangular waveforms is divided into a horizontal portion and a waveform portion and the waveform portion has an exponential function waveform that is raised or lowered to determine the state of the spent fuel Comparing the radiation intensity graph with a reference graph to determine the number of rectangular waveforms; Comparing the radiation intensity graph with a reference graph to determine whether the stepped waveform is rising or falling and determining a current state of the basket; And comparing the radiation intensity graph with a reference graph to ascertain whether the exponential waveform of the waveform portion is rising or falling and determining loading progress information of the basket at the present time.

The present invention provides a post-use fuel loading diagnostic system and method including an optical fiber. As a result, it is possible to confirm the loading process of the sealed container containing the spent fuel or the spent fuel, whether or not the loading is completed, the loading state, and whether the spent fuel is taken out.

Fig. 1 is a view showing a reservoir for storing spent fuel.
2 is a schematic diagram of a spent fuel loading diagnostic system according to an embodiment of the present invention.
FIG. 3 is a schematic view showing a state where a spent nuclear fuel loading diagnostic system according to an embodiment of the present invention is installed in a storage room.
FIG. 4 is a view showing the optical fiber shown in FIG.
FIG. 5 is a view illustrating a collimator disposed in a shielding structure in which the optical fiber shown in FIG. 4 is inserted.
FIG. 6 is a view showing a state where a plurality of collimators shown in FIG. 5 receive radiation.
7 is a diagram illustrating a reference graph according to an embodiment of the present invention.
8 is a radiation graph showing a situation in which a basket containing spent fuel has been loaded into the storage cylinder.
FIG. 9 is a radiation graph showing a situation in which a basket containing spent fuel has been taken out of the storage cylinder.

Hereinafter, examples of the present invention will be described in more detail with reference to specific drawings. However, the scope of the present invention is not limited to the embodiments and drawings described below. Various equivalents and modifications may be made from the embodiments described in the following description and the drawings.

The terminologies used herein are terms used to describe embodiments of the present invention, which may vary depending on the user, the intention of the operator, or the practice of the field to which the present invention belongs. Therefore, the definition of these terms should be based on the contents throughout this specification.

For reference, in order to facilitate understanding, each component and its shape or the like are briefly drawn or exaggerated in the above drawings. The same reference numerals denote the same elements in the drawings.

Configuration of spent fuel loading diagnostic system

2 is a schematic diagram of a spent fuel loading diagnostic system according to an embodiment of the present invention. FIG. 3 is a schematic view showing a state where a spent nuclear fuel loading diagnostic system according to an embodiment of the present invention is installed in a storage room.

Referring to FIGS. 2 and 3, the spent fuel loading diagnostic system according to an embodiment of the present invention includes an optical fiber 100, an optical sensor 200, and a server 300.

The optical fiber 100 is exposed to radiation and converts the radiation into light. The optical fiber 100 may be made of a glass fiber having a strong temperature change and a high radiation durability. Meanwhile, the optical fiber 100 may be formed by bundling a plurality of glass fibers to improve the sensitivity to radiation. The optical fiber may be linearly extended so that the spent fuel 20 can be inserted into the storage 10 accommodated in the basket 30. On the other hand, the detected radiation may be a gamma ray.

The optical sensor 200 converts the light transmitted through the optical fiber 100 into an electrical signal to generate an electrical signal. The optical sensor 200 may include a photodetector (not shown), and the photodetector may be a charge-coupled device (CCD), a photodiode, or a photomultiplier tube (PMT) .

The server 300 determines the stored information of the spent nuclear fuel by calculating the electric signal as a radiation intensity graph. The server 300 includes a reference graph storage unit 301, a comparison unit 302, and an operation unit 303.

The reference graph storage unit 301 stores a reference graph that varies depending on the number of the baskets 30 of the spent nuclear fuel 20 in the spent fuel 20 stored in a basket unit.

The basket (30) is an example of a sealed container containing spent fuel (20). Any container that can seal the spent fuel 20 in addition to the basket 30 can be used in the present invention.

The comparator 302 converts the electrical signal generated by the optical sensor 200 into a radiation intensity graph and compares the electrical signal with the reference graph.

The calculating unit 303 calculates the comparison result of the comparison unit 302 to determine the storage information of the spent nuclear fuel.

Actual installation example of spent fuel accumulation diagnostic system

3 to 6, an example in which the spent fuel loading diagnostic system according to an embodiment of the present invention is installed in the storage 10 using the above components will be described. The above installation example is only an embodiment of the present invention, and the spent fuel loading diagnostic system of the present invention can be used in a spent fuel pool of various structures.

FIG. 4 is a view showing the optical fiber shown in FIG. FIG. 5 is a view illustrating a collimator disposed in a shielding structure in which the optical fiber shown in FIG. 4 is inserted. FIG. 6 is a view showing a state where a plurality of collimators shown in FIG. 5 receive radiation.

As shown in FIG. 4, first, one shielding structure 50 is disposed. At least one storage cylinder 40 on which the basket 30 containing the spent nuclear fuel 20 is placed is juxtaposed to the outer periphery of the shielding structure 50. For example, four storage cylinders 40 are arranged at the front, back, right, and left sides of the one shielding structure 50. The storage cylinder (40) may include a plurality of baskets (30) storing spent nuclear fuel.

An optical fiber (100) of a linear shape extending in the longitudinal direction is disposed inside the shielding structure (50). The optical fiber 100 detects the radiation emitted from the basket 30 stored from the upper surface to the lower surface of the storage cylinder 40. Therefore, the shielding structure 50 and the optical fiber 100 are extended from the upper surface of the storage cylinder 40 along the bottom surface. The optical fiber 100 may be wrapped with an optical fiber shield 60 to prevent unwanted noise components from entering and to prevent damage.

The shielding structure 50, the optical fiber 100 and the four storage cylinders 40 constitute one module, and a plurality of the modules are installed in the storage 10.

As shown in FIG. 5, a plurality of collimators 70 may be installed in the shielding structure 50 at regular intervals along the bottom surface from the upper surface of the shielding structure 50. The plurality of collimators 70 may be a path for the optical fiber 100 to collect radiation. The predetermined interval is equal to the height of the basket (30). Accordingly, a plurality of collimators 70 are formed in layers by the number of baskets 30 stored in the storage cylinder 40. For example, if ten basket 30 are stored in the storage cylinder 40, the plurality of collimators 70 may be formed in ten layers.

In other words, the plurality of collimators 70 may be arranged in the front, back, left, and right sides of the shielding structure 50 in a plurality of layers corresponding to the height of the basket 30, And coincides with the height of the basket (30). 6, when the basket 30 is completely filled in the storage cylinder 40, the plurality of collimators 70 are moved to the basket 30 in order to receive the radiation from each basket 30, Are arranged corresponding to the positions where they are stored.

The spent nuclear fuel loading diagnostic system according to an embodiment of the present invention can be applied to the reservoir 10 having the above structure and a radiation intensity graph plotting a certain shape according to a radiation exposure position of the optical fiber 100 is obtained, The radiation intensity graph may be compared with a reference graph to determine the stored information of spent fuel.

In the following, the loading diagnostic method according to the spent fuel loading diagnostic system will be described in detail.

How to diagnose the spent fuel loading

A plurality of baskets (30) containing spent fuel are stored one by one from the inner upper surface of the storage cylinder (40) along the inner bottom surface. The radiation value measured through the optical fiber 100 is a value measured at the basket 30 located on the top surface of the storage cylinder 40 that is less than the radiation value measured at the basket 30 located at the bottom of the storage cylinder 40 It is bigger. The reason for the above phenomenon is that the optical fiber 100 experiences light loss depending on the distance to the optical sensor 200 where the actual electrical signal is detected. That is, the attenuation of the radiation value occurs depending on the distance from where the radiation is measured to where the electrical signal is detected. Therefore, when the radiation of the basket 30 moving in any one of the storage cylinders 40 is measured by the optical fiber 101, a graphical radiation value is obtained in which the energy is attenuated exponentially.

The method for diagnosing the spent fuel loading using the exponential decaying radiation intensity graph is as follows.

The optical fiber 100 is used to detect radiation and convert it into light and transmit it. And then converts the transmitted light into an electrical signal for transmission. Then, the electric signal transmitted is calculated by a radiation intensity graph. After the reference graph is generated and prepared, the radiation intensity graph is compared with the reference graph. Finally, the storage information of the spent fuel 20 stored in units of the basket 30 is determined using the comparison result.

7 is a diagram illustrating a reference graph according to an embodiment of the present invention. Referring to FIG. 7, the reference graph is a graph that predicts how the spent fuel 20 will be drawn when it is carried in or out.

Wherein the reference graph has a stepped waveform having an ascending or descending waveform, the stepped waveform having the same number of rectangular waveforms as the number of baskets (30) of the spent nuclear fuel (20), and each of the rectangular waveforms Is divided into a horizontal portion and a wave portion, and the wave portion may have an exponential waveform that rises or falls. Therefore, it is possible to diagnose the stored information of the spent nuclear fuel 20 by comparing the waveform of the actually obtained radiation intensity graph with the reference graph. The reference graph shown in FIG. 7 is a graph showing a situation in which n baskets 30 are being loaded into the storage bin 10.

The storage information of the spent nuclear fuel 20 may include information on carry-over of the spent fuel 20 in the basket 30, information on the export of the spent fuel 20 in the basket 30, Information on loading of the basket 30 of the spent nuclear fuel 20, and information on the number of baskets of the spent nuclear fuel 20.

In the step of determining the storage information of the spent nuclear fuel, the number of the rectangular waveforms is first determined by comparing the radiation intensity graph with the reference graph. The number of the rectangular waveforms means the number of the baskets 30 immediately. Then, the radiation intensity graph is compared with a reference graph to ascertain whether the stepped waveform is rising or falling, and the loaded state of the basket 30 is determined. The loaded state of the basket 30 means that the current basket 30 has been loaded or unloaded. The ascending step-like waveform means that all the baskets 30 are currently in the completed state, and the descending step-like waveform means that all of the baskets 30 are now in the completed state. That is, the loaded state of the basket 30 containing the spent spent fuel 20 can be known through the stepped waveform. Thereafter, the radiation intensity graph is compared with a reference graph to determine whether the exponential waveform is rising or falling, and whether the loading of each basket 30 is proceeded or not is determined. The rise of the exponential waveform means that one basket 30 is currently being carried out and the descent of the exponential waveform means that one basket 30 is currently being carried in. A specific example will be described with reference to FIGS. 8 and 9. FIG.

Specific examples of the method of diagnosing the loading of spent nuclear fuel

8 is a radiation graph showing a situation in which a basket containing spent fuel has been loaded into the storage cylinder. FIG. 9 is a radiation graph showing a situation in which a basket containing spent fuel has been taken out of the storage cylinder.

As discussed above, since the shape of the reference graph drawn when the spent nuclear fuel is carried in or out is known, it is possible to analyze the converted radiation intensity graph detected in the optical fiber.

Referring to FIG. 8, there is shown an example of a converted radiation intensity graph generated by generating light from the optical fiber 100 as an electric signal and calculating the electric signal. The graph of FIG. 8 is composed of a total of nine rectangular waveforms from a1 to a9, and has a rising stepped waveform. Each of the rectangular waveforms is divided into a horizontal portion and a waveform portion. 8, the waveform portion of a1 has an exponential waveform of a falling waveform. Based on the above information, the stored information of the spent nuclear fuel is determined as follows. First, since the graph is composed of a total of nine rectangular waveforms, it can be seen that the number of the basket 30 loaded on the storage cylinder 40 is nine. And since the graph shows a rising stepped waveform, it indicates that the current 9 baskets are now in the completed state. In addition, since the waveform of the exponential function is lowered, it can be confirmed that the loading of each basket is in progress. The number of the baskets 30 is merely an example, and the number of the baskets 30 may be changed according to the situation of the actual storehouse 10.

Referring to FIG. 9, there is shown an example of a converted radiation intensity graph generated by generating light from the optical fiber 100 as an electric signal and calculating the electric signal. The graph of FIG. 9 consists of a total of nine rectangular waveforms from b1 to b9, and has a descending step-like waveform. Each of the rectangular waveforms is divided into a horizontal portion and a waveform portion. 9, the waveform portion of b9 has an exponential function waveform of rising form. Based on the above information, the stored information of the spent nuclear fuel is determined as follows. First, since the graph is composed of a total of nine rectangular waveforms, it can be seen that the number of the basket 30 loaded on the storage cylinder 40 is nine. And since the graph has a descending step-like waveform, it indicates that the current 9 baskets have been completely unloaded. In addition, since the waveform of the exponential function of the waveform part is raised, it can be confirmed that the state in which each basket is being taken out is proceeding. The number of the baskets 30 is merely an example, and the number of the baskets 30 may be changed according to the situation of the actual storehouse 10.

The spent fuel loading diagnostic system and method described above are merely illustrative, and the scope of protection of the present invention may include various modifications and equivalents to those skilled in the art.

10: Reservoir 20: Spent fuel
30: basket 40: storage cylinder
50: shielding structure 60: optical fiber protective tube
70: Collimator
100: Optical fiber 200: Light sensor
300: server
301: Reference graph storage unit 302:
303:

Claims (7)

An optical fiber that is exposed to radiation and converts the radiation into light and transmits the light;
An optical sensor for converting the light transmitted through the optical fiber into an electric signal to generate an electric signal; And
And a server for calculating storage information of the spent nuclear fuel by calculating the electric signal transmitted by the radiation intensity graph,
The server comprises:
A reference graph storage unit for storing a reference graph in which the waveform varies depending on the number of baskets storing the spent nuclear fuel;
A comparator for converting the electrical signal generated by the optical sensor into a radiation intensity graph and comparing the electrical signal with the reference graph; And
And an arithmetic unit operable to calculate a comparison value in the comparison unit to determine storage information of the spent nuclear fuel,
Wherein the optical fiber is linearly extended so that the spent nuclear fuel can be inserted into a storage container accommodated in the basket,
In the reference graph,
Having a stepped waveform that rises or falls,
Wherein the stepped waveform has the same number of rectangular waveforms as the number of baskets storing the spent nuclear fuel,
Wherein each of the rectangular waveforms has a waveform portion, the waveform portion has an exponential waveform that rises or falls,
Wherein the calculation unit determines that the basket storing the spent nuclear fuel is taken out when the waveform part included in the radiation intensity graph has an exponential function waveform and if the waveform part has a descending exponential function waveform, The spent fuel loading diagnostic system judges that the storing basket is brought in. delete The method according to claim 1,
Wherein the radiation is a gamma ray. delete The method according to claim 1,
The optical sensor includes a light detecting portion,
Wherein the optical detection unit is any one of a charge-coupled device (CCD), a photodiode, and a photomultiplier tube (PMT). The method according to claim 1,
The storage information includes:
Information on the basket of the spent fuel, information on carrying out the basket of the spent fuel, information on the loading process of the spent fuel, information on the completion of the basket loading of the spent fuel, and information on the number of the basket of the spent fuel Wherein the fuel is a fuel. The optical sensor receiving light converted from the radiation from the optical fiber when the optical fiber is exposed to radiation;
Converting the light transmitted from the optical sensor into an electrical signal and transmitting the electrical signal to a server;
Computing the electrical signal transmitted by the server with a radiation intensity graph;
The server generating and preparing a reference graph;
The server comparing the radiation intensity graph and the reference graph; And
And the server determining storage information of the spent fuel to be stored in units of a basket using the comparison result,
In the reference graph,
Having a stepped waveform that rises or falls,
Wherein the stepped waveform has the same number of rectangular waveforms as the number of baskets of spent fuel,
Wherein each of said rectangular waveforms has a waveform portion, said waveform portion has an exponential waveform that rises or falls,
In the step of the server determining the storage information of the spent nuclear fuel,
The server comparing the radiation intensity graph with the reference graph to determine the number of rectangular waveforms;
Comparing the radiation intensity graph with the reference graph to determine whether the stepped waveform is rising or falling and determining a current state of the basket;
The server compares the radiation intensity graph with a reference graph to confirm whether the exponential waveform of the waveform portion is rising or falling; And
When the server has the exponential function waveform having the rising waveform portion, it is determined that the basket for storing the spent nuclear fuel has been taken out, and if the waveform portion has the descending exponential function waveform, the basket for storing the spent fuel is brought in The method comprising the steps of:

Images