KR100701623B1 - Fuel bundle extracting device, defuelling device, and method using the same under power-off condition of Nuclear power plant - Google Patents

Abstract

In the nuclear fuel discharge device and method of the present invention, the fuel is discharged while the fuel is stopped in the nuclear power plant, the fuel is inserted into the pressure pipe loaded with the fuel, and the fuel is discharged while being pushed down by the flow of the cooling water as a fluid flowing upstream and downstream of the pressure pipe. Providing a fuel discharge device and method characterized in that it has the effect of significantly reducing the fuel discharge time when the nuclear power plant shuts down.

Description

Fuel bundle extracting device, defueling device, and method using the same under power-off condition of Nuclear power plant

1 is an overall perspective view of a nuclear fuel release device (DFD) which is a first embodiment of the present invention;

2 is a longitudinal cross-sectional view of the DFD device of FIG. 1;

3 is an enlarged cross-sectional view of a connection portion of the DFD device of FIG. 2;

4 is an enlarged cross-sectional view of an orifice ring of the DFD device of FIG. 2;

5 is an overall perspective view of a nuclear fuel release device (DFD) which is a second embodiment of the present invention;

6 is a longitudinal sectional view of the DFD device of FIG. 5;

7 is an enlarged cross-sectional view of an orifice ring of the DFD device of FIG. 5;

8 schematically illustrates a conventional fuel exchange method;

9A is an overall perspective view of a conventional fuel exchanger;

FIG. 9B is an internal cross sectional view for showing a magazine device provided in the inside of the FIG. 9A device; FIG.

10 is a process diagram sequentially showing a nuclear fuel exchange process of the prior art;

11 is a longitudinal sectional view of a grapple of the prior art; And

12 is a cross-sectional view showing a conventional fair tool.

1. Field of invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defuelling device (hereinafter referred to as 'DFD') in a heavy water reactor fuel channel and a method thereof. More specifically, the present invention relates to a nuclear fuel release device installed inside a nuclear fuel channel to efficiently discharge nuclear fuel when a power plant is shut down and a method using the same.

Korea's nuclear power plants are divided into heavy water and light water. Among them, natural uranium is used for heavy water reactors, and heavy water (D ₂ 0) is used as a moderator for primary cooling system and is used as a medium for heat exchange. Heavy water reactors are characterized by the ability to exchange fuel during operation, and have associated fuel exchange facilities and several related systems for exchanging fuel during operation.

Fuel replacement during operation is carried out in the same direction as the fluid flow of the primary system coolant in the pressure tube, with fresh fuel loaded upstream and spent fuel discharged downstream. The fresh fuel loaded upstream is loaded into the pressure tube by the ram device of the fuel exchanger and flows downstream by the flow resisting force in the coolant flow direction, and the used fuel is pushed by the loaded fresh fuel to enter the downstream fuel exchanger. The flow pressure of the fluid during operation is usually about 20 kg / s. In this pressure range, it is possible to push the fuel with fresh fuel without any equipment. However, since the flow rate in the pressure tube disposed at the outermost side of the reactor during operation is smaller than the central portion, a part of the pressure tube is additionally provided with a pair tool to replace fuel in the outermost pressure tube. have. Fairtool is a replacement aid that only applies to a small number of pressure tubes during operation of the plant.

In addition, pressure pipes used in nuclear power plants should be checked for abnormality through regular inspections, and after stopping operation, removing fuel from the pressure pipe, pressure pipe volume inspection (FCVI), pressure pipe material analysis (PTSS), and garter spring position calibration work ( Inspections for soundness assessment, such as slats, etc., should be carried out to prevent abnormalities in the pressure pipe during operation.

When stopping for this periodic inspection or during a period of regular maintenance, the grapple system is used to drain the fuel in the pressure tube because the flow rate in the pressure tube is not as high as in normal operation. I'm making it. However, the fuel exchanger is used to connect a plurality of devices are used for a long time, various problems appear in the interconnection, there is a problem that can occur excessively fuel discharge time. When using the grapple system, the fuel discharge time from one pressure tube is 3 hours in Korea, which is about 1140 hours when there are 380 pressure tubes in the reactor.

The present invention has the knowledge that the development of a new type of DFD reduces the fuel discharge time in the pressure tube to quickly and efficiently replace the fuel during shutdown, and significantly increase the operating time of the power plant. .

2. Detailed description of the prior art

First, we look at the overall structure involved in the exchange and release of nuclear fuel employed by the CANDU-6 type system in Canada.

In FIG. 8, a charge machine 310 as a nuclear fuel exchanger disposed on the right side of a reactor 300 in which a plurality of pressure tubes are arranged therein usually includes a magazine, and the reactor after loading fuel in the new fuel loading region. It is fitted on the upstream side of the pressure pipe of the, the discharge device 310 '(accept machine) disposed on the left side of the reactor 300 has the same configuration as the loading device 310, is fitted on the downstream side of the pressure pipe is discharged downstream After receiving the on-fuel, it is transported to the fuel discharge zone.

9A and 9B show a nuclear fuel exchanger used as the loading and discharging device, FIG. 9A shows an overall perspective view of the fuel exchanger, and FIG. 9B shows an internal configuration of a magazine device provided in this fuel exchanger. have.

The nuclear fuel exchanger 310 includes a magazine section 311, a ram assembly 312, a snout assembly 313, a separator 314, a clamp 315, and a ram drive mechanism 316. . The magazine section 311 has twelve nuclear fuel stations, each having a space to store at least two-thirds of the fuel contained in one channel, and is designed to be rotated in a fixed cell. The ram section including the ram assembly 312 pushes the fuel string out of the latch, receives the fuel string in the carrier tube and positions it for proper removal. The snout assembly 313 is a mechanism for attaching a nuclear fuel tube device to an end fitting of a pressure tube.

The magazine device 317 shown in FIG. 9B is installed inside the magazine section 311. The ram head 312 'is disposed inside the centrally located tube, and for example, twelve magazine tubes 318 forming a nuclear fuel station around the tube are arranged, for example, as shown in the rear view. The fuel is attached to the tube B, the tube D, the tube F, the tube L, and the tube N. Tube (A) is a snout plug, tube (C) is a channel plug, tube (E) is a guide sleeve, tube (H) is a shield plug, tube (J) is an adapter, and tube (K) is an extra channel plug Tube M contains a respective unshown mechanism for adjusting the extra shield plug. During the fuel exchange operation, these tubes are rotated in turn to be located in the tube region to perform their respective functions and transfer the operation to the next tube. The number of magazine tubes and fuel-loading tubes, and the function that each tube rotates, are adapted according to the surrounding operating equipment and power generation capacity. In addition, the nuclear fuel exchanger described above is utilized as the discharge device 310 'in the same configuration, in which case it is rotated to receive the fuel discharged from the pressure tube on the empty space of the fuel tube.

The fuel exchange operation by the nuclear fuel exchanger described above will be described with reference to the principle diagram showing the flowchart of the fuel exchange operation in FIG.

In the pressure tube 310 ″ arranged in the center of the figure, twelve fuel bundles to be exchanged are located, and a charge device 310 and an exhaust device 310 ′ are located on the left and right sides of the pressure pipe. In the magazine device of the device 310 and the discharge device 310 ', five fuel tubes are used, and each fuel tube of the loading device 310 has two fuel bundles. As it rotates, a total of eight fuel bundles are loaded and replaced, and four existing fuel bundles remain in the pressure tube, and the arrow in the figure shows the direction in which the coolant moves.

In step 1A of FIG. 10, each of the rams 320 and 320 'retracts the plug plugs 321 and 321' to the entrance of the magazine device. 322 and 322 'are shielding plugs disposed upstream and downstream of the pressure tube, respectively. In step 2A, the plug plugs 321 and 321 'are pivoted into the magazine device by the rotation of a magazine tube (e.g., tube C in Figure 9b), and the ram 320 is shielded plug 322. ) Is retracted to the magazine device, the ram 320 'is connected to the shield plug 322' in position. In step 3A, the first tube containing fuel is brought to the loading position pushed by the ram 320 by the rotation of the magazine tube, and correspondingly the shielding plug is inserted into the magazine device by the rotation of the tube receiving it. Is turning. In step 4A, the ram 320 loads two fuel bundles inside the fuel tube. If the process (3A, 4A) is repeated four times according to the continuous rotation of the magazine tube, all fuel bundles (8) of the fuel tube are arranged in order at the inlet side of the pressure tube as shown in the drawing to push the spent fuel downstream. To start. In this final position, the most downstream fuel bundle reaches the inlet side of the magazine device of the discharge device 310 '. It should be noted that the shield plug 322 'is retracted in advance by the ram 320' to facilitate the discharge of the spent fuel in step 4A.

The subsequent process is mainly the action of the discharge device (310 '). That is, in the processes 5A and 6A, the empty fuel tubes of the magazine device of the discharge device 310 'receive two fuel bundles pushed out downstream, and then rotate, and the next empty fuel tubes for waiting are discharged. Come. During this process, the side stop 324 'intervenes and holds the fuel bundle so that subsequent fuel bundles do not interfere with the magazine device. This process 5A, 6A is repeated four times so that the spent fuel bundles are all contained within the magazine apparatus. Steps 7A and 8A are steps for returning the shielding plug and the plug plug released in the previous step to their original positions.

The above-described fuel exchange method uses a mechanical system, and a peripheral member such as a magazine device is significant in that it can be applied to the DFD of the present invention described later.

 Next, the nuclear fuel replacement method using the grapple system currently used in the domestic Wolsong No. 1 when the power plant is shut down is basically based on the structure similar to the prior art, and the grapple is upstream through the ram device of the fuel exchanger. It is a method of receiving nuclear fuel pushed out from the downstream by inserting it into the pressure tube from the side. After connecting the pressure pipe and the fuel exchange device and removing the snout plug, the channel plug, and the shield plug, seven grapples are inserted into the pressure pipe one by one using the ram device to receive nuclear fuel downstream. 11 shows such a grapple system 340, the left end of which is connected to a fuel adapter, and the extension 341 is a portion of which is gradually extended in length by an upstream exchanger to push out fuel. However, such a system has a fundamental limitation in that the grapple is a mechanical system in which the grapple needs to be held in direct contact with the fuel and has to extend its length by connecting several extensions. have.

In addition, the nuclear fuel replacement method using a fair tool is a method used to select a pressure tube that requires fuel replacement during the operation of a nuclear power plant, and to replace the consumed fuel. In the outer area, since the flow rate is relatively small, it is difficult to exchange fuel by its own force, so the fuel is pushed down to the downstream side by inserting a pair mechanism into the pressure tube to give flow resistance. 12 shows a cross-sectional view of a typical fair tool. Since the internal configuration of the fair tool is known, a detailed description thereof will be omitted. In the case of replacing eight fuel bundles as shown in FIG. 10, the fair tool moves to the loading position by rotating the magazine device after all eight fuel bundles have been loaded upstream of the pressure tube. As it is advanced downstream, the fuel bundle is pushed by the fluid flow resistance. Once the fuel bundle has been discharged downstream, the magazine unit is rotated again to recover the fair tool.

However, the fair tool system described above is applied only to a small number of pressure tubes disposed at the outside of the power plant during operation, and has a simple cylindrical structure, which deteriorates as an effective flow resistor in a low flow range, and thus delays fuel discharge time. There is.

In addition, a fundamental limitation of the above-described prior arts is that they do not have a fuel discharging device capable of efficiently releasing the entire nuclear fuel in the heavy water reactor pressure tube in the stopped state of the power plant. The fair tool system is applied only to the pressure tube near the outermost part of the power plant in operation, so it cannot be applied in the low flow range according to the stop. The grapple system used in the stop state is structurally connected by extending several extensions. Inefficiency is inherent. In addition, the CANDU-6 system has a problem that the equipment is complicated and expensive and the existing facilities have to be changed when applied domestically.

Therefore, the present invention provides a novel discharge device that can effectively perform fuel discharge in the low flow rate range during stop operation based on the pair device currently used in the power plant for the purpose of nuclear fuel exchange during operation. It aims to do it.

The present invention is to provide a discharge device that can perform the function even in the expanded diameter range and the deflection of the pressure tube corresponding to the end of the operation through the enhancement to add a new function to the existing pair device The purpose.

In order to achieve the above object, the nuclear fuel discharging device of the present invention is inserted into a pressure tube loaded with fuel, and flows while pushing the fuel downwards under the force of the flow of cooling water as a fluid flowing from the upstream to the downstream of the pressure tube. When the fuel release device of the present invention is provided with an orifice ring strengthened, it forms a pressure drop region of the fluid flowing between the pressure tubes. Furthermore, when the orifice ring has a groove on its outer circumference, the thrust received by the fuel discharge device is further increased. You can expect

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Further, the fuel emitting device of the present invention forms a connection portion consisting of a first connection portion and a second connection portion in an intermediate portion, and provides a structure that allows each of these connection portions to be moved relatively within a small range, and thus the end of operating life. In spite of the internal bending caused by the deflection of the pressure tube, the pressure tube can flexibly proceed inside the pressure tube.

Furthermore, the present invention provides a method for rapidly exchanging fuel by efficiently releasing fuel when a nuclear power plant is stopped using the nuclear fuel discharge device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the fuel discharge device (DFD) of the present invention is inserted into the pressure tube by the ram mechanism of the above-described magazine device when the fuel of all nuclear fuel channels (pressure tubes) is to be replaced in the stopped state of the nuclear power plant, and the flow resistance of the coolant is inserted. It is based on the principle of pushing down the nuclear fuel using.

That is, the present invention, the DFD itself is a kind of flow resistance due to the installation in the pressure tube of the DFD, so that the narrow channel through which the coolant flows between the outer periphery of the DFD and the pressure tube through the movement path of the DFD, DFD Pushes the fuel while moving toward the downstream side of the pressure pipe, so that even if the flow rate of the coolant flowing through the pressure pipe is slow, such as when the power plant is stopped, all fuel bundles located in the pressure pipe can be moved smoothly. He has the knowledge of the invention.

In terms of the design requirements of the DFD, in terms of general requirements, it must be able to be linked to existing fuel handling and storage systems, to be corrosion resistant to coolants such as heavy water and water, and to be able to discharge fuel using minimum flow rates at stationary power plants. do. In terms of functional requirements, one end must be able to link with the ram handling it, and the fuel must be fully discharged from the upstream side to the downstream side, and after completion of use, the DFD must be able to be discharged to the discharge port smoothly. .

Within the scope of meeting these design requirements, the present invention discloses two types of DFDs (DFD-A type, DFD-B type).

Composition of the DFD-A Type

Fig. 1 is an overall perspective view showing the DFD-A of the present invention, and Fig. 2 is a sectional view taken along the longitudinal center line of the apparatus. 1 and 2, the configuration of the DFD-A apparatus 1 of the present invention will be described.

 The device 1 of the present invention is bordered left and right on the basis of the flexible connection 20. The fuel adapter 10 located at the left end of the drawing of the device 1 is arranged towards the downstream side of the pressure tube as a part in direct contact with the fuel bundle. Holes were machined in the cross section and a plurality of line grooves were installed at the circumference for smooth fluid flow to prevent vibration caused by the fluid flow. The cylinder tube 12A extends long such that the left end thereof is connected to the fuel adapter 10 and the right end thereof is coupled to the connection part 20. Several circular slots perforated in tube 12A are for increasing flow resistance. In addition, two orifice rings 30 and 30 are positioned at appropriate intervals between the intermediate portion of the tube 12A and the connection portion 20, and the outer circumferential surface of the cylinder tube 12A is disposed between the orifice rings 30 and 30. Surrounding cylindrical spacer tubes 14A and 14A are provided. The spacer tube is configured to hold the proper position of the orifice ring 30. In addition, spacer tubes 14B and 14B and orifice rings 30 and 30 are alternately located from the right side of the connection portion 20. In the space formed by the spacer tubes 14B and 14B, the cylinder tube 12B is located inscribed with these tubes. The casing 18 located at the right end of the drawing of the device 1 is a part which serves to support the spring and the stem which will be described later, and is associated with the ram of the fuel exchanger. The tubes and sleeve 16 are guided and supported by the casing 18. The stem s installed in the space formed by the sleeve 16 and the casing 18 is a portion directly connected to the ram of the fuel exchanger, and is chrome plated on the outer surface thereof. The spring s' is to allow the RAM to engage smoothly when combined with the DFD.

In the overall assembled state of Fig. 1, the maximum length of the apparatus 1 of the present invention is preferably not more than 1 meter, and the outer circumferential surface diameters at the left and right ends are preferably about 1 centimeter. Moreover, it is preferable that the material of each part of the apparatus 1 of this invention is manufactured from the stainless material of STS304.

Next, the connection part 20 of the apparatus 1 of this invention is demonstrated in detail with reference to FIG.

The connection part 20 of the present invention is composed of a first connection part 20A and a second connection part 20B.

The first connection portion 20A is composed of a cylindrical base 21A having an insertion groove 22A formed at the center thereof, and a coupling portion 23A extending to engage the cylinder tube 12A above and below the base 21A. have. In addition, the boundary surface 211A of the portion where the base 21A faces the second connection portion 20B has a shape in which the top and bottom surfaces are symmetric with respect to the center line l of the insertion groove 22A. On the right side of the figure) is composed of two stages inclined smoothly toward the rear end. The inclined surface may be formed in a columnar shape having a large radius of curvature. In a preferred embodiment of the present invention, when the diameter (D) of the boundary surface 211A is 88 mm, the distance (d) between the leading point and the trailing end point is preferably about 4.8 mm, but these values are various in the pressure tube. The enemy can change according to variables and operating conditions.

The second connection portion 20B of the present invention comprises a cylindrical base 21B and a coupling portion 23B extending to engage the cylinder tube 12B above and below the base 21B. An insertion groove 22B having the same diameter as the insertion groove 22A is formed in the center portion of the base at a short distance, and an insertion groove 222B having a smaller diameter is formed behind it. The insertion groove 22B may be made smaller in diameter than the insertion groove 22A. In addition, the boundary surface 211B of the portion where the base 21B is in contact with the boundary surface 211A of the first connection portion 20A is formed with a smooth inclined surface complementary to the shape of the boundary surface 211A.

As can be seen from the above description and FIG. 2, the connection part 20 has the bolts B inserted grooves 22A and 22B while the interface 211A and 211B of the primary and secondary connection parts maintain intimate abutment contact. Assembled by fastening through, 222B). The connection parts 20A and 20B are not separated by the fastening of the bolts, but since the boundary surfaces 211A and 211B form sliding sliding contacts, the connection parts 20A and 20B face the connection parts. It is possible to move and flow in the longitudinal direction (axial direction of the DFD) and radial direction (the outer circumferential direction of the DFD) within a small range with respect to (20B, 20A). Therefore, the connection part 20 of the present invention provides the action that the left and right extensions are relatively movable and movable relative to the connection part located in the central portion of the longitudinal direction of the DFD device 1. The advantage of the DFD apparatus 1 of the present invention is that the left and right sides of the DFD apparatus 1 are aligned with respect to the connection portion so that the pressure tube and the center line correspond to the expansion or deflection of the pressure tube according to the change over time, so that the flow path of the coolant is always constant. To provide. This can be likened to the fact that the position of the member is automatically aligned with the flow of the flow, for example with respect to the appropriate articulation point of motion when the coolant is full and subjected to buoyancy in the water. In this respect, the DFD device of the present invention is defined as having a flexible connection. As a result, the existing pair tool was manufactured as an integral type variable position type, and was unable to follow a constant and continuous flow of flow by elastically responding to a pressure tube that is easily changed locally under the action of high pressure.

Moreover, the flexible connection of the present invention provides the function of allowing the DFD to flow smoothly from upstream to downstream through the deflection pressure tube.

In the present invention, the insertion holes 22A and 22B into which the bolt B is inserted are formed to span two members, and the length of the insertion hole 22B formed in the second connection portion 20B is relatively short. This is advantageous in that the connection portions 20A and 20B have an unbalanced distribution of the tightening force of the bolt fastening portions to ensure the relative movement of each connection portion more smoothly.

The connection part of this invention demonstrated above shows the preferable example, and various deformation | transformation is possible within the range which can achieve the function of "flexible connection." For example, the boundary surface 211A of the first connection portion 20A may be formed as a concave surface, the boundary surface 211B of the second connection portion may be formed as a convex surface, or the insertion groove may be formed as a straight groove having no step.

4 is an enlarged view of the orifice ring 30 of the present invention. Four protrusion ribs 34 are provided on the outer circumference of the orifice ring 30, and grooves 32 are formed between the ribs 34. The height of the grooves is preferably about 1 cm, for example. Orifice ring 30 is fitted to the body of the DFD serves to increase the fluid resistance, the groove 32 serves to reduce the sensitivity to changes in the inner diameter of the pressure tube. In general, the more grooves are machined around the ring, the greater the flow resistance. In the present invention, the installation number and the installation interval of the orifice ring 30 can be changed as appropriate.

According to the analysis result of the applicant, the number of installation of the orifice ring and the thrust (force pushing the DFD) has a proportional relationship, and it is confirmed that the thrust also increases as a groove is added to the surface of the orifice ring. As such, the presence and structure of the orifice ring closely affects the flow resistance of the DFD device.

Composition of DFD-B Type

The device 1 'of the DFD-B type of the present invention is based on the same configuration and principle as the device 1, but differs in that it can cope with a sudden flow rate change in the pressure tube. Fig. 5 is an overall perspective view showing the DFD-B of the present invention, and Fig. 6 is a sectional view taken along the longitudinal center line of the apparatus. With reference to these figures, the DFD apparatus 1 'is demonstrated centering on difference with the apparatus 1. As shown in FIG. The member of the part corresponding to the apparatus 1 has been described with the same number.

The DFD device 1 'is provided with a fuel adapter 10', a cylinder tube 12 ', a connection portion 20', a spacer tube 14 ', and an orifice ring in order from the side facing the fuel (left side of the drawing). 30 '), sleeve 16' and casing 18 '. The orifice ring 30 'is formed to a longer length than the device 1, and at least one slot is formed on the outer circumference thereof (see Fig. 7).

In addition, the device 1 'extends across the full length of the spacer tube 14' and the orifice ring 30 'at the end of the connection portion 20' and is connected to the casing 18 '. 20 ", an orifice spring 33 'housed within the tube adapter 20 " and installed at one end of the tube adapter to extend over the entire length of the orifice ring 30', and the orifice ring 30 '. And a spring holder 32 'extending from the installation area of the tube adapter to one end of the tube adapter 20 ". The tube adapter 20" supports the orifice ring and the orifice spring, and has a slot-shaped hole at the bottom thereof. 21 "is formed. Although the holes 21" are shown as one in FIG. 6, four holes are formed at uniform intervals over the entire outer periphery. The hole of the orifice ring (see FIG. 7) and the hole 21 ″ of the tube adapter 20 ″ are radially aligned, through which the key 31 ′ is inserted. The orifice spring 33 'is installed to mitigate the impact of the rapid increase in flow rate and is supported by the spring holder 32'.

In the DFD device 1 'of the present invention, the spring 31' has a sudden flow while the orifice ring 30 'and the spring holder 32' are prevented by the key 31 '. Since the flow of the orifice ring 30 'is directed, the flow rate increases rapidly, so that the DFD device 1' can be effectively prevented from swinging around the orifice ring providing the flow channel. Exert.

In the device 1 'of the present invention, the configuration and operation of the connection portion 20' are the same as those of the device 1 described above, and a stem and a spring for supporting the same are also provided in the device 1 '. have.

The DFD apparatus of the present invention described above is supplied from the upstream side of the pressure tube by the fuel exchanger utilized in the conventional grapple system or the fair tool system, and discharges the fuel downstream while pushing the fuel while flowing in the pressure tube. It is recovered to the side and received in the magazine tube of the fuel exchanger. Although this method is the most typical example, the shape of the DFD device of the present invention can be used for all types of fuel exchange devices existing or to be developed as long as it satisfies the basic premise that it is used for exchanging fuel in a power station shutdown state. It should be noted that may be applied by altering the enemy.

In addition, to stop the power generation of the nuclear power plant in order to use the nuclear fuel discharge device of the present invention described above, some of the coolant pumps which are stopped to increase the fluid flowing from the upstream to the downstream of the pressure tube, or to push the fuel downstream of the pressure tube Various methods such as the stop operation for increasing the flow rate can be used in combination.

The present invention described above has the superior effect of significantly reducing the existing fuel exchange time by providing a nuclear fuel release device installed in the nuclear fuel channel to efficiently load the nuclear fuel when the power plant stops operating. Currently, the time required to replace all 380 pressure tube fuels in Korea is about 1140 hours (average 3 hours per channel), but when using the DFD device of the present invention, the fuel can be efficiently discharged into the flow at least 50% of time and cost. It is expected to achieve savings.

In addition, the DFD apparatus of the present invention has a structure that can be flexibly changed in response to the deflection of the pressure tube according to the change over time, install an orifice ring to increase the thrust, and can maintain a stable flow attitude in preparation for a sudden increase in flow rate It has the effect of providing an excellent flow device in terms of configuration and operation, such as providing a structure that is.

Claims (9)

In the operation state of the heavy water reactor type nuclear power plant, the fuel is inserted into the loaded pressure tube and is pushed into the downstream by the flow of the coolant as a fluid flowing from the upstream to the downstream of the pressure tube. A nuclear fuel discharge device characterized in that at least one orifice ring (30) is installed around it. delete The method of claim 1, The orifice ring is provided with a rib portion (34) is provided with at least one groove (32) to increase the thrust of the fuel discharge device by the flow, characterized in that the fuel discharge device. The method according to any one of claims 1 to 3, The fuel discharging device includes a connection portion 20 at an intermediate portion, the connection portion including a first connection portion 20A and a second connection portion 20B, and the first connection portion and the second connection portion. Interfaces 211A and 211B which are inseparably fastened by a fastening member and are in contact with corresponding respective connection parts are formed to be in abutment contact with at least a portion thereof, so that the first and second connection parts are connected to respective corresponding connection parts. Nuclear fuel release device, characterized in that the relative movement within a small range. The method of claim 1, The nuclear fuel discharge device is a fuel adapter 10 in direct contact with the fuel bundle, the left end is connected to the fuel adapter and the right end is extended to the first cylinder tube (12A) extending to engage with the connection portion 20, the left end is the connection A second cylinder tube 12B connected to the portion and connected to the casing for receiving a sleeve associated with the fuel exchanger, the at least one orifice ring 30 being disposed on the first cylinder tube and the second cylinder tube. Nuclear fuel release device, characterized in that is installed. The method of claim 1, The nuclear fuel discharge device is a fuel adapter 10 'in direct contact with the fuel bundle, the left end is connected to the fuel adapter and the right end is a cylinder tube 12' elongated to engage with the connection portion 20 ', the left end is the The right end includes a spacer tube 14 'connected to the connection portion and connected to a casing for receiving a sleeve associated with the fuel exchanger, wherein at least one orifice ring 30' having a slot is installed on the spacer tube. And an orifice spring (33 ') is inserted from the surface facing the connection portion of the spacer tube to the orifice, and a key (31') is inserted through the slot of the orifice ring. The force of the flow of cooling water as a fluid flowing from the upstream to the downstream of the pressure pipe during the shutdown of the heavy water reactor type nuclear power plant using the nuclear fuel discharge device according to any one of claims 1, 3 and 5 to 6. Receiving a nuclear fuel discharge method characterized in that for discharging the fuel by allowing the fuel discharge device to flow while pushing the fuel downstream. delete When the heavy water reactor-type nuclear power plant stops operating by using the nuclear fuel discharge device according to claim 4, the nuclear fuel discharge device flows while pushing the fuel downstream by receiving the force of cooling water as a fluid flowing upstream and downstream of the pressure pipe. A method of releasing fuel, comprising releasing fuel.

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