Compressed gas injection device

Abstract

To provide a device capable of removing safely, an obstacle when taking out, fuel which has been used, from a fuel storage rack.SOLUTION: There is provided a compressed air injection device X for removing an object which is an obstacle when taking out, fuel which has been used from a fuel storage rack comprising a plurality of rack cells, the device comprises: a device main body 1; a fixing mechanism 2; a control part 3. The device main body 1 comprises: a movement mechanism 11; and an injection mechanism 12. The movement mechanism 11 can move the injection mechanism 12 in a three-dimensional state, and the injection mechanism 12 includes a nozzle main body 12a1. The nozzle main body 12a1 has; a coanda nozzle part cd whose diameter is gradually increased as going to a forefront part on a tip end part thereof; and a suction hole it for sucking fluid in the surrounding. The fixing mechanism 2 can fix the device main body 1 to the fuel storage rack, the control part 3 can remotely operate, the fixing mechanism 2, and the movement mechanism 11, and the injection mechanism 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a device for removing obstacles during spent fuel removal work.

Background Art

[0002] Due to the impact of the Great East Japan Earthquake that occurred in March 2011, a hydrogen explosion occurred at Unit 3 of the Fukushima Daiichi Nuclear Power Plant. Debris from the reactor building damaged by the explosion scattered as rubble on the fuel storage racks in the spent fuel pool.

[0003] The rubble entered the gaps between the channel boxes covering the fuel assemblies, the channel fasteners fastening the channel boxes and the fuel assemblies, and the gaps between the channel boxes and the rack cells, hindering the work of removing the spent fuel.

[0004] However, there has never been a suitable device for safely removing the rubble that entered the gaps between the channel boxes and the channel fasteners, and the gaps between the channel boxes and the rack cells on the fuel storage racks located at a special location, about 7 m deep in the spent fuel pool.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above situation, and an object to be solved is to provide a device capable of safely removing obstacles when removing spent fuel from a fuel storage rack.

Means for Solving the Problems

[0007] To solve the above problems, the present invention provides a compressed gas injection device for removing objects that obstruct the removal of spent fuel from a fuel storage rack composed of multiple rack cells, The device comprises a main body, a fixing mechanism, and a control unit, and the main body of the device has a moving mechanism and a spraying mechanism. The aforementioned moving mechanism is configured to allow the injection mechanism to move in three dimensions. The injection mechanism includes a nozzle body, The nozzle body is provided with a Coanda nozzle section at its tip that gradually widens in diameter as it approaches the tip, and a suction hole for drawing in surrounding fluid. The fixing mechanism is configured to fix the main body of the device to the fuel storage rack, The control unit is configured to remotely control the fixing mechanism, the moving mechanism, and the injection mechanism.

[0008] According to the present invention, the device can be fixed on a fuel storage rack, the injection mechanism can be moved remotely, and obstacles can be removed by the force of the jet sprayed from the nozzle body. Furthermore, the Coanda nozzle and intake holes allow for the incorporation of surrounding water into the jet, which increases the jet's power and effective range compared to a gas-only jet.

[0009] In a preferred embodiment of the present invention, the moving mechanism includes an X-axis moving device, a Y-axis moving device, and a Z-axis moving device for linearly moving the injection mechanism along each axis.

[0010] This configuration allows for efficient removal of obstacles on a fuel storage rack, which consists of multiple rack cells arranged in a grid pattern.

[0011] In a preferred embodiment of the present invention, the X-axis moving device, the Y-axis moving device, and the Z-axis moving device each include an instrumentation unit capable of measuring the amount of movement on each axis of the injection mechanism.

[0012] This configuration allows the spatial position of the injection mechanism to be represented in spatial coordinates and understood numerically, thereby improving the accuracy and efficiency of the work.

[0013] In a preferred embodiment of the present invention, the instrumentation unit is configured to be able to inject compressed gas into it.

[0014] This configuration allows the internal pressure of the instrumentation unit to be kept higher than the external water pressure by injecting compressed gas, thereby preventing water from entering the instrumentation unit and, consequently, preventing water damage to the instrumentation equipment.

[0015] In a preferred embodiment of the present invention, the nozzle body is inclined in the direction of its spray.

[0016] This configuration allows the jet stream to be directed at obstacles that are difficult to reach from directly above. For example, if an obstacle is caught in the gap of a channel fastener located on the top of the channel box covering the fuel assembly, the jet can be directed directly at the obstacle from the side, even if the area directly above the obstacle is covered by the channel fastener.

[0017] In a preferred embodiment of the present invention, the injection mechanism includes a plurality of nozzle bodies whose injection directions are oriented in different directions.

[0018] With this configuration, even if an obstacle is caught in the gap between the two leaf springs on the two sides of the channel fastener, which is positioned to sandwich the corner of the top of the channel box, the jet stream can be simultaneously injected from multiple nozzles to remove it all at once, allowing the work to proceed quickly.

[0019] In a preferred embodiment of the present invention, the injection mechanism includes a camera unit capable of photographing the injection direction of the nozzle body.

[0020] This configuration allows users to safely remove obstacles while visually confirming the condition of the obstacles and channel boxes.

[0021] In a preferred embodiment of the present invention, the control unit is configured to be able to perform a jog operation on the moving mechanism.

[0022] With such a configuration, fine adjustment of the injection direction can be easily performed, so that the accuracy and safety of the work are improved.

[0023] In a preferred embodiment of the present invention, the control unit is configured to be able to automatically control the moving mechanism so that the injection mechanism comes to the center of gravity position of the apparatus main body.

[0024] With such a configuration, the center of gravity adjustment when installing this apparatus with a crane can be easily performed, so that the safety and efficiency of the crane work are improved.

[0025] In a preferred embodiment of the present invention, the fixing mechanism has a plurality of main fixing devices, and the plurality of main fixing devices are substantially columnar bodies that can be inserted into the rack cell.

[0026] With such a configuration, by inserting the main fixing device into the rack cell, the apparatus according to the present invention can be easily installed in the fuel storage rack.

[0027] In a preferred embodiment of the present invention, the plurality of main fixing devices each include an auxiliary fixing device for fixing the main fixing device in the rack cell.

[0028] With such a configuration, the main fixing device inserted into the rack cell is more firmly fixed, so that the apparatus according to the present invention can sufficiently withstand the reaction force during high-pressure jet injection.

Advantages of the Invention

[0029] According to the present invention, it is possible to provide an apparatus that can safely remove obstacles when taking out used fuel from a fuel storage rack.

Brief Description of the Drawings

[0030] [Figure 1] These are schematic perspective views and side views of a compressed gas injection device according to an embodiment of the present invention. [Figure 2] These are schematic perspective views, side views, and plan views of an injection mechanism according to an embodiment of the present invention. [Figure 3] This is an example of a jet injection operation according to an embodiment of the present invention. [Figure 4] This is a schematic diagram of a nozzle body according to an embodiment of the present invention. [Figure 5] This is a schematic diagram of a fixing mechanism according to an embodiment of the present invention. [Figure 6] This is an example of an operation screen displayed on a control unit according to an embodiment of the present invention. [Figure 7] This is a schematic perspective view of a compressed gas injection device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0031] The compressed gas injection apparatus according to an embodiment of the present invention will be described below with reference to Figures 1 to 7. Note that the embodiments shown below are examples of the present invention and the present invention is not limited to these embodiments. Also, the symbol X refers to the compressed gas injection apparatus according to an embodiment of the present invention.

[0032] In Figures 1 to 7, pipes for supplying compressed gas, hydraulic fluid, etc., to each part, as well as wiring for transmitting video and other signals, power supply, etc., are not depicted. However, the proper connections of these pipes and wiring will be easily understood by those skilled in the art.

[0033] As shown in Figure 1(A), the compressed gas injection device X comprises a device body 1, a fixing mechanism 2, and a control unit 3.

[0034] The main body of the device 1 includes a moving mechanism 11 and an injection mechanism 12. The moving mechanism 11 includes an X-axis moving device 11a, a Y-axis moving device 11b, and a Z-axis moving device 11c. Details of the injection mechanism 12 will be described later.

[0035] The X-axis moving device 11a includes a hydraulic motor om, an instrumentation unit is, a ball screw bs, and a slide rail sr.

[0036] In other words, the X-axis moving device 11a converts the rotational motion of the hydraulic motor om into linear motion using a ball screw bs, thereby enabling the Y-axis moving device 11b, the Z-axis moving device 11c, and the injection mechanism 12 to move linearly in the X-axis direction. The slide rail sr assists in this linear movement.

[0037] Furthermore, since the instrumentation unit is can measure the X-axis movement amount from the rotation amount of the hydraulic motor om, it is possible to measure the X coordinate of the injection mechanism 12 based on these values.

[0038] Furthermore, the instrumentation unit is includes a connection port cn, through which compressed gas can be injected into the instrumentation unit is. This allows the internal pressure of the instrumentation unit is to be maintained at a level higher than the external pressure, and in particular underwater, it is possible to prevent water from entering the instrumentation unit is.

[0039] Furthermore, the Y-axis moving device 11b and the Z-axis moving device 11c are implemented with the same configuration as the X-axis moving device 11a.

[0040] The Y-axis moving device 11b can linearly move the Z-axis moving device 11c and the injection mechanism 12 in the Y-axis direction, and the instrumentation unit is can measure the Y-coordinate of the injection mechanism 12.

[0041] The Z-axis movement device 11c can linearly move the injection mechanism 12 in the Z-axis direction, and the instrumentation unit is can measure the Z coordinate of the injection mechanism 12.

[0042] Therefore, the X-axis moving device 11a, the Y-axis moving device 11b, and the Z-axis moving device 11c work together to move the injection mechanism 12 in three dimensions, and the spatial coordinates of the injection mechanism 12 can be measured from the amount of movement on each axis measured by the instrumentation unit is of each device.

[0043] The fixing mechanism 2 comprises a first main fixing device 21 that is roughly columnar in shape and a second main fixing device 22, which are attached to the main body of the device 1 via a base ba.

[0044] The control unit 3 has a main breaker for controlling the power supply to the main unit 1 and the fixing mechanism 2, and a touch panel (not shown) for controlling other operations, and is installed in a location separate from the main unit 1 and the fixing mechanism 2.

[0045] Figure 1(B) is a side view (partially omitted) of the device X, viewed from direction AA'. The first main fixing device 21 includes a plurality of columnar bodies 21a and an auxiliary fixing device 21b, and similarly the second main fixing device 22 includes a plurality of columnar bodies 22a and an auxiliary fixing device 22b.

[0046] As shown in Figure 2(A), the injection mechanism 12 includes a plurality of nozzle bodies 12a1, 12a2 and a plurality of camera units 12b1, 12b2, respectively.

[0047] The camera unit 12b1 includes a camera body cm capable of photographing the spray direction of the nozzle body 12a1, and a camera fixing part br. A video signal transmission line cb is connected to the camera body cm. A general-purpose underwater camera and its accessories can be suitably used for the camera body cm and the transmission line cb. Furthermore, the camera unit 12b2 is capable of photographing the spray direction of the nozzle body 12a2 and is configured similarly to the camera unit 12b1.

[0048] Figure 2(B) is a side view of the injection mechanism 12 as seen from the nozzle body 12a1 side. As shown here, the injection direction of the nozzle body 12a1 is tilted to a predetermined angle. The same applies to the nozzle body 12a2.

[0049] Figure 2(C) is a plan view of the injection mechanism 12 with the camera sections 12b1 and 12b2 omitted. As shown here, the injection directions of the nozzle bodies 12a1 and 12a2 are directed in substantially orthogonal and different directions.

[0050] Figure 3(A) is a top view of the obstacle removal process, where the channel box fb covering the spent fuel is fastened to the fuel assembly by a channel fastener cf located at one corner of its upper end. The channel fastener cf is a device that connects the channel box fb and the fuel assembly with its screw threads, and also has a pair of leaf springs on two sides that are used to maintain the distance between fuel assemblies within the reactor.

[0051] Figure 3(B) is a side view of the work in progress. The rack guide section Lg at the top of the fuel rack is narrower than the inner diameter of the rack cell. During normal fuel extraction, the leaf spring of the channel fastener cf contacts and is pushed against the rack guide section Lg, causing it to flex inward as the fuel is extracted. However, as shown in Figure 3(B), if an obstacle ob gets inside the leaf spring of the channel fastener cf, even if the rack guide Lg contacts the leaf spring of the fastener during fuel retrieval, the leaf spring cannot be pushed down due to the obstacle ob and cannot pass through the rack guide Lg.

[0052] In other words, if an obstacle ob gets into the gap between the channel fastener cf and the channel box fb, these will interfere with the rack guide Lg, making it impossible to remove the channel box fb (spent fuel).

[0053] In other words, this device X removes the obstruction ob that has entered the inside of the leaf spring of the channel fastener cf using a jet of compressed gas, thereby resolving the interference between the channel fastener cf and the rack guide Lg, and allowing the channel box fb (spent fuel) to be removed.

[0054] Furthermore, for structural reasons, there is a risk of nozzle damage if the compressed gas pressure exceeds 2 MPa. Therefore, it is preferable to use this device X when the compressed gas pressure is 2 MPa or less, and the set upper pressure limit for this device X is actually 2 MPa.

[0055] As shown in Figure 2(B), the nozzle bodies 12a1 and 12a2 are given a predetermined inclination in the direction of injection, so even if the area directly above the obstacle ob is covered by the channel fastener cf, the jet can be directed at the obstacle ob from the side.

[0056] As shown in Figure 2(C), the injection directions of the nozzle bodies 12a1 and 12a2 are directed in substantially orthogonal and different directions. Therefore, even if an obstacle ob is caught between both of the pair of channel fasteners cf, the jet can be directed at each obstacle ob at once to remove it.

[0057] In other words, the configuration of the injection mechanism 12 is suitable for the situation shown in Figure 3(B).

[0058] Figure 4 is an enlarged view of the tip of the nozzle body 12a1, with the dotted line indicating the internal structure. The tip of the nozzle body 12a1 is provided with a Coanda nozzle section cd that gradually expands in diameter as it approaches the tip, and a suction hole it for drawing in surrounding fluid.

[0059] The Coanda nozzle section cd forms a roughly frustoconical space at the tip of the nozzle body 12a1.

[0060] The suction holes (it) are provided at the very tip of the nozzle in eight locations, connecting the Coanda nozzle section (cd) with the space outside the nozzle.

[0061] In the Coanda nozzle section cd, a pressure difference is created between the inside and outside as a high-speed gas jet gj passes through the inside of the nozzle body 12a1. This pressure difference draws in external fluid through the suction hole it. In other words, in a spent fuel pool, water is drawn in.

[0062] As a result, the gas jet gj flows down as a gas-liquid mixed jet gw (shaded area) that incorporates water from around the nozzle at eight points in the circumferential direction of the nozzle, thus improving the power and range of the jet compared to a gas-only jet.

[0063] Furthermore, the tip of the nozzle body 12a2 is configured in the same way as the nozzle body 12a1.

[0064] As shown in Figures 5 and 1(A), the first main fixing device 21 is configured such that a plurality of columnar bodies 21a surround the auxiliary fixing device 21b, and the overall shape is roughly columnar, with the outer dimensions being slightly smaller than the inner diameter of the rack cell. Therefore, as shown in Figure 5, the base ba and thus the main body of the device 1 (not shown) can be roughly fixed onto the fuel storage rack fL simply by inserting the first main fixing device 21 into the rack cell fc.

[0065] The auxiliary fixing device 21b includes a hydraulic cylinder os, a conversion mechanism co, and a bracing part tm.

[0066] Because the direction of the force is converted by the conversion mechanism co, as shown in Figure 5(A), when the hydraulic cylinder os is lowered, a force acts to retract the bracing part tm. Furthermore, as shown in Figure 5(B), when the hydraulic cylinder os rises, a force acts to cause the bracing portion tm to protrude, and when the bracing portion tm comes into contact with the rack guide portion Lg, a fixing force can be obtained. Furthermore, the user can control the up and down movement of the hydraulic cylinder os from the control unit 3, and can switch between the fixed and unfixed states of the auxiliary fixing device 21b from the control unit 3.

[0067] Furthermore, the second main fixing device 22 is configured in the same way as the first main fixing device 21, and the fixing mechanism 2 has multiple main fixing devices 21 and 22, which allows the device X to be fixed more securely.

[0068] Figure 6 shows an example of the operation screen displayed on the touch panel of the control unit 3. As shown in Figure 6(A), the control unit 3 can perform increment operations on the injection mechanism 12 at high or low speed while checking the current coordinates of the injection mechanism 12.

[0069] Therefore, the user can select any axis and speed, and while pressing either "forward rotation" or "reverse rotation," they can increment the movement mechanism 11 so that the injection mechanism 12 moves slightly on the selected axis, thus easily making fine adjustments to the injection position.

[0070] Furthermore, as shown in Figure 6(B), the control unit 3 is configured to automatically control the movement mechanism 11 so that the injection mechanism 12 is positioned at the center of gravity of the device body 1, based on a preset center of gravity coordinate.

[0071] Therefore, the user can move the spray mechanism 12 to the center of gravity of the device body 1 simply by pressing the "Start Movement" button, thereby improving safety and work efficiency when lifting the device with a crane.

[0072] As shown in Figure 7, the device X is installed in the fuel storage rack fL by crane lifting. Therefore, the device X further comprises a roughly box-shaped frame section fr, and the frame section fr has a lifting hook sh and a hook receiving base hr. This makes rigging work easier when lifting objects with a crane, thus improving work efficiency.

[0073] According to this embodiment, since the tip portions of the nozzle bodies 12a1 and 12a2 are provided with a Coanda nozzle portion cd and a suction hole it, respectively, the compressed gas jet can be ejected as a gas-liquid mixed jet with improved power and range.

[0074] Furthermore, since the moving mechanism 11 includes an X-axis moving device 11a, a Y-axis moving device 11b, and a Z-axis moving device 11c, the injection mechanism 12 can be moved linearly on a fuel storage rack fL composed of multiple rack cells arranged in a grid, enabling efficient removal of obstacles.

[0075] Furthermore, since the X-axis moving device 11a, the Y-axis moving device 11b, and the Z-axis moving device 11c each include an instrumentation unit is capable of measuring the amount of movement on each axis of the injection mechanism 12, the spatial position of the injection mechanism can be numerically determined, improving the accuracy and efficiency of the work.

[0076] Furthermore, since the instrumentation unit is configured to allow the injection of compressed gas, the internal pressure of the instrumentation unit is can be kept higher than the external water pressure by injecting compressed gas, thereby preventing water from entering the instrumentation unit is and, consequently, preventing water damage to the instrumentation equipment.

[0077] Furthermore, because the nozzle bodies 12a1 and 12a2 are angled in the direction of their jets, the jets can be directed onto obstacles that are difficult to reach from directly above.

[0078] Furthermore, since the injection mechanism 12 includes multiple nozzle bodies 12a1 and 12a2 whose injection directions are oriented in opposite directions, even if an obstacle is caught between both sides of a pair of channel fasteners, the jet can be injected simultaneously to remove it all at once.

[0079] Furthermore, since the injection mechanism 12 includes camera units 12b1 and 12b2 capable of photographing the injection direction of the nozzle bodies 12a1 and 12a2, obstacle removal work can be safely performed while visually confirming the condition of obstacles and channel boxes.

[0080] Furthermore, since the control unit 3 is configured to allow the movement mechanism 11 to be moved in increments, the spray direction can be easily fine-tuned, thereby improving the accuracy and safety of the work.

[0081] Furthermore, since the control unit 3 is configured to automatically control the movement mechanism 11 so that the injection mechanism 12 is positioned at the center of gravity of the device body 1, the center of gravity can be easily adjusted when installing the device X on a crane, thereby improving the safety and efficiency of crane operations.

[0082] Furthermore, the fixing mechanism 2 has a plurality of main fixing devices 21 and 22, and the plurality of main fixing devices 21 and 22 are substantially columnar bodies that can be inserted into rack cells, so that the main fixing devices 21 and 22 can be inserted into rack cells and the device X can be easily installed on the fuel storage rack fL.

[0083] Furthermore, since each of the multiple main fixing devices 21 and 22 includes auxiliary fixing devices 21b and 22b for fixing the main fixing devices 21 and 22 within the rack cell, the device X is firmly fixed and can withstand the reaction force during high-pressure jet injection.

[0084] It should be noted that the configurations and functions shown in the above-described embodiments are merely examples and can be modified in various ways based on design requirements, etc. [Explanation of Symbols]

[0085] X Compressed gas injection device 1. Main unit of the device 11 Moving mechanism 11a X-axis moving device 11b Y-axis moving device 11c Z-axis moving device 12 Injection mechanism 12a1, 12a2 Nozzle Body 12b1, 12b2 Camera section 2 Fixing mechanism 21 First main fixing device 21a Column 21b Auxiliary fixation device 22 Second main fixing device 22a Column 22b Auxiliary fixation device 3. Control Unit is Instrumentation Department CD Coanda nozzle section it suction hole fb channel box cf channel fastener ob obstacle

Claims

1. A compressed gas injection device for removing an object trapped between a rack cell and the spent fuel, which obstructs the removal of spent fuel from a fuel storage rack composed of multiple rack cells, The device comprises a main body, a fixing mechanism, and a control unit. The main body of the device has a moving mechanism and a spraying mechanism. The aforementioned moving mechanism is configured to allow the injection mechanism to move in three dimensions. The injection mechanism includes a nozzle body, The fixing mechanism is configured to fix the main body of the device to the fuel storage rack, The control unit enables remote operation of the fixing mechanism, the moving mechanism, and the injection mechanism. Consists of, A compressed gas injection device wherein the nozzle body is inclined such that its injection direction is directed between the rack cell and the spent fuel.

2. The compressed gas injection device according to claim 1, wherein the nozzle body is provided with a Coanda nozzle portion at its tip that gradually expands in diameter as it approaches the tip, and a suction hole for drawing in surrounding fluid.

3. The compressed gas injection apparatus according to claim 1 or 2, wherein the moving mechanism includes an X-axis moving device, a Y-axis moving device, and a Z-axis moving device for moving the injection mechanism linearly along each axis.

4. The X-axis moving device, the Y-axis moving device, and the Z-axis moving device each include an instrumentation unit capable of measuring the amount of movement on each axis of the injection mechanism. The compressed gas injection device according to claim 3, wherein the instrumentation unit is configured to be able to inject compressed gas thereto.

5. The compressed gas injection device according to any one of claims 1 to 4, wherein the injection mechanism includes a plurality of nozzle bodies whose injection directions are oriented in different directions.

6. The compressed gas injection device according to any one of claims 1 to 5, wherein the control unit is configured to be able to increment the moving mechanism.

7. The compressed gas injection device according to any one of claims 1 to 6, wherein the control unit is configured to automatically control the movement mechanism so that the injection mechanism is positioned at the center of gravity of the main body of the device.

8. The aforementioned fixing mechanism has a plurality of main fixing devices, The compressed gas injection device according to any one of claims 1 to 7, wherein the plurality of main fixing devices are substantially columnar bodies that can be inserted into the rack cell.

9. The compressed gas injection apparatus according to claim 8, wherein each of the plurality of main fixing devices includes an auxiliary fixing device for fixing the main fixing device within the rack cell.

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