KR0158085B1 - Precision grip head assembly for nuclear fuel rod withdrawal process - Google Patents

Abstract

The present invention draws the fuel rods from the spent fuel assembly having high radioactivity within a limited shielded space and arranges them densely and packs them in a storage or disposal container to save space for storing or disposing of spent fuel. In order to reduce the shielding space and work efficiency by implementing the lower stationary dismantling device of the spent fuel assembly and the precision fuel closing device for fuel rod extraction in one device (head assembly), The present invention relates to an apparatus capable of increasing the stability of the work.

Description

Integrated head assembly for assembly disassembly and precision gripping of randomly arranged fuel rods for remote dry withdrawal of spent fuel rods

1 is a remote dry draw system configuration of the spent fuel rods of the present invention.

2 is a plan view of the head assembly of the present invention.

3 is a side view of the head assembly of the present invention.

4 is a detailed view of the nuclear fuel rod gripping device of the present invention.

* Explanation of symbols for main parts of the drawings

1 nuclear fuel assembly fixing table 3 nuclear fuel assembly fixing apparatus

4,8,9: LM Guide 10,11,12: Servo Motor

13: holding device 14: impact trench

The present invention relates to a head assembly incorporating a spent fuel assembly disassembly function and an irregularly arranged fuel rod precision gripping function required for a remote dry withdrawal process of a spent fuel rod of the present invention, and more specifically, within a limited working space of a radiation shielding facility. In a rod consolidation system, the fuel rods can be remotely withdrawn from the highly radioactive spent fuel assembly and packed tightly in storage or disposal containers to reduce the space required for storing or disposing of spent fuel. Designed as a unit (head assembly) for dismantling the lower fixture of the spent fuel assembly and for discharging the fuel rod as a single unit (head assembly), the spent fuel rod to reduce radiation shielding space and increase working efficiency Remote dry withdrawal process Dismantling the assembly functions and precise gripping of a random disposition fuel bongdan function relates to integrated head assembly.

In general, spent fuel that has been combusted and fired in a reactor has not been able to maintain the regular fuel rod arrangement at the time the assembly was first loaded into the reactor core due to thermohydrodynamic conditions at high temperature and high pressure. In other words, the nuclear fuel rod has a large deviation from the reference position in the axial direction and its maximum value is about 22 mm). If you pull out the fuel rods without holding them correctly, you will get a problem.

In addition, in order to withdraw the fuel rods from the spent fuel assembly, it is necessary to remove the fastening nut supporting the bottom end piece of the assembly. There was a problem that could damage the fuel rods.

The present invention has been made in order to solve the above problems, in order to safely withdraw the spent fuel rods from the fuel assembly, dismantle the bottom fixed plate of the assembly using an impact trench and precisely grasp the fuel rod ends to the weak parts of the nuclear fuel rods. Provides a device for withdrawing fuel rods with as little damage as possible, and saves shielding work space by designing the decommissioning of the dense process performed in the radiation shielding space and fuel rod withdrawal as a single device Therefore, the purpose is to reduce the enormous costs for the construction and operation of the facility.

In order to achieve the above object, in the present invention, the coil spring is mounted on the driver system of the gripping device unit so as to accommodate the change in the axial position of each fuel rod in the fuel assembly which may occur during the combustion of the nuclear fuel at the nuclear reactor core. A gripping device unit designed to allow the instrument to withdraw the fuel rod by gripping the fuel rod irrespective of the irregular arrangement of the fuel rod, and an impact wrench device unit for performing the function of disassembling the bottom fixing plate of the spent fuel assembly. The link device, which allows the gripping device and the impact trench device to perform their respective functions as required, is mounted in one head assembly, so that the assembly dismantling and fuel rod withdrawal work can be completed in one device. Spent fuel dense ball by assembly device design It is possible to reduce the radiation shielding space, which requires expensive construction costs by integrating the dismantling bottom plate and the fuel rod withdrawal device, which are essential for the assembly, into one unit, and to efficiently and safely perform the remote concentration of spent fuel rods. Characterized in that.

Hereinafter, the configuration and operation effects in detail in connection with the accompanying drawings of the present invention will be described.

1 is a schematic diagram of a remote dry take-out system of the spent fuel rod of the present invention, wherein the assembly fixing table 1, which is an apparatus used for the remote take-out of spent fuel rods during the dry dense process of the spent fuel assembly, is formed. The fuel rod withdrawal table 100 and the head assembly 200 are coupled to one side of the fixed table 1, and the nuclear fuel assembly holding device 3 is fixed to both upper ends of the fixed table 1 and the fixed device ( 3) The nuclear fuel assembly 2 is fixed with a plurality of fixing screws (not shown), and X, Y, and Z axis servo motors 12, 10, and 11 are fixedly installed at upper ends of the drawing table 100, respectively. And Y, Z-axis LM guides (8, 9), and also to form a Y-axis ball screw (7) to be fixed to the head assembly (200).

In addition, the impact prevention system drive electric motor 19 and the plurality of impact prevention guides 20 are installed in the takeout table 100, and the horizontal movement system drive motor 16 and the plurality of nuclear fuel rods are disposed on the side surface of the takeout table 100. The horizontal feeder 17 is connected to the horizontal feed system drive shaft 18, and the X-axis LM guide 4 is installed outside the rear end of the take-out table 100, but the X-axis ball screw is formed at one side of the LM guide 4 (5) is installed to form a fixed number of frames (6) and the temporary storage rack 21 is fixed to one side of the withdrawal table (100).

Reference numeral 22 in the accompanying drawings is a tightening nut removing container.

2 is a plan view of the head assembly of the present invention, FIG. 3 is a side view of the head assembly of the present invention, and FIG. 4 is a detailed view of the fuel rod gripping device of the present invention. In the head assembly 200 integrally formed in the head assembly 200, the impact trench portion 14 and the gripper portion 13 are mounted on the head assembly 200, and a link system 32 is installed at the bottom of the impact trench portion 14. The coil spring 34 is installed on both sides of the impact trench part 14, and the gear box 33 and the AC motor 30a are connected to one side of the impact trench part 14.

The link system 32 installs an AC motor 30b on one side, and fixes the ball screw 37 and the LM guide rail 36 to the AC motor 30b. On one side, the LM guide block 35 is fixed, but the LM guide block 35 is connected to the impact trench portion 14.

The coil spring 29 is installed on both sides of the gripping device 13, and the ball screw 26 having the spring 28 mounted inside the gripping device 13 is installed. 27) the AC motor 30, which operates the slider 27, is fixedly installed at one side of the gripping device unit 13.

In addition, a gripping mechanism 23 having a spring 25 inserted therein is formed on one side of the gripping device part 13, and the gripping mechanism 23 is connected to a ball screw 26 and a gripping mechanism outside the gripping mechanism 23. It is the structure which fixed the support 24.

Reference numeral 38 in the accompanying drawings is a nuclear fuel rod, 39 is an Inconel support grid.

The operation of the present invention will be described with reference to the above configuration.

In order to reduce the storage and disposal space of spent fuel in a light water reactor, the fuel rod withdrawal device of the spent fuel rod dense system which draws out and rearranges the spent fuel rods 38 and repacks them in a storage container or a disposal container. As shown in FIG. 1, the spent fuel rod extracting device is a head assembly 200 which is a core part of the fixed table 1 for fixing the spent fuel assembly 2 and the nuclear fuel assembly 2 fixed thereto. The apparatus of the present invention is a head assembly 200 located above the withdrawal table 100 to extract the fuel rod 38 from the nuclear fuel rod 38. Convenience and safety of work by simultaneously performing disassembly and withdrawal functions using one head assembly 200 that was performed in separate devices, and Maximizes the utilization of the up space and first dismantles the lower fixture of the assembly fixed to the fixed table 1 by using the impact trench 14 of the head assembly 200, and the irregular fuel rod 38 in the assembly. The fuel rod gripping device 13 is capable of carrying out the fuel rod withdrawal by detecting the position sufficiently and holding the fuel rod gripping device 13 capable of precisely holding the end of the rod.

In addition, in the device of the present invention, the link system 32 linking the functions of the impact trench 14 for carrying out the lower fixing plate (not shown) and the gripping device 13 for the nuclear fuel rod 38 withdrawal operation are performed. The bottom portion of the impact trench 14 is installed so that the impact trench 14 and the gripper 13 mounted on the head assembly 200 do not interfere with each other.

The head assembly 200 is a three-axis (x, y and z) of the impact trench portion 14 and the gripping device 13 according to the position of the tightening nut (not shown) and the nuclear fuel rod 38 of the lower end fixing body The servo motors (10, 11, 12) having excellent control characteristics were used as a power source for position control because they need to be moved to the shaft).

When the nuclear fuel assembly dismantling operation is not performed, the gripper unit 13 remains in a forward state, but when the nuclear fuel assembly 2 dismantling operation is started, the impact trench unit 14 is connected to the gripper unit 13 by the connecting device. You will be more advanced. At this time, the impact trench 14 extends forward from the gripper 13 so that the impact nut 14 may be long enough not to be interfered with by the gripper while dismantling the fixing nut of the lower fixed plate of the spent fuel assembly. The mechanical equipment for the forward movement of the impact trench part 14 used an LM guide and a ball screw. An AC motor was used for power transmission. The positions of the impact trench 14 are controlled by the AC servomotors 10, 11, and 12 provided on the part and the left side, respectively.

The AC servomotor is positioned in the impact wrench section 14 at the position of a tightening nut supporting the lower fixing plate by a database of a computer that is input in advance according to the type of spent fuel assembly. ) When the position control is completed, the impact trench part 14 starts to operate at a low speed in order to loosen the tightening nut. During this operation, the impact wrench part is removed from the lower fixing plate and the impact trench part is prepared for loss in the shielded space. (14) Coil springs 34 are provided on both sides, and this coil spring 34 acts to push the tightening nut with a maximum deviation of 22 mm, so that the force of the coil spring 34 even after the tightening nut is completely loosened. The nut is left in the lower fixing plate to fall into the tightening nut removing container 22 prepared between the impact trench portion 14 and the lower fixing plate. All. Due to this operation, after the one tightening nut is removed, the impact trench is moved to the position of the next tightening nut by the database, and the above operation is repeated to release all the tightening nuts supporting the lower fixture, and then the fixing plate. Remove it.

As described above, when the bottom fixing plate removal work of the spent fuel assembly 2 is completed, the connecting part is operated to retreat the impact trench part 14 to its original position, and the three-axis shape is performed like the lower fixing plate dismantling work using the impact trench part 14. Each of the electric motors (30, 30a, 30b) for controlling the position of the fuel rod gripper (collet) 13 to the position of each fuel rod 38 previously input to the computer according to the type of nuclear fuel assembly approaching Let's do it. At this time, in case the position of the spent fuel rod is irregular (deviation from the axial reference position of the fuel rod), as shown in FIG. 4, the action of the coil spring 29 located on both sides of the gripping device 13 and the gripping mechanism ( The spring 25 acts on the inside of the gripping mechanism 23 so that the front part of the 23 opens in the left and right directions, and is designed to sufficiently accommodate even the largest irregular arrangement of the nuclear fuel rods 38. 23) and the holding mechanism support 24 is operated back and forth by a slider (27) connected to the ball screw 26 by the operation of the AC motor (30), and the grip when the slider 27 is advanced Since the mechanism 23 is closed and, on the contrary, the holding mechanism 23 is opened when retreating, and the distance that the holding mechanism 23 can be advanced as far as possible is up to the Inconel spacergrid 39 of the fuel assembly. Gripping mechanism ( Regardless of the position of the nuclear fuel rod that should be grasped by 23, the gripping mechanism support 24 remains stopped after the groove portion in front of the gripping mechanism 23 touches the nuclear fuel rod. At this time, the gripping device portion 13 is actually moved forward by the driving device, but the gripping mechanism 23 is in a state where the mouth is opened at the nuclear fuel end position by the contracting action of the coil springs 29 located at both sides.

After the preparation work for holding the nuclear fuel rod 38 is completed as described above, when the slider 27 is advanced by the AC motor 30, the front part of the holding mechanism 23 is closed by the holding mechanism support 24. And thus firmly hold the fuel rods. At this time, the whole of the head assembly 200 retreats backward and starts to withdraw the fuel rod 38 from the fuel assembly 2. Therefore, even if the nuclear fuel rod is pushed down or raised by the high temperature and high pressure thermohydrodynamic conditions of the reactor core, the gripping device portion of the apparatus of the present invention can accurately hold the nuclear fuel rod and can safely withdraw the fuel rod efficiently.

As described above, the present invention provides the impact trench portion 14, which is a lower plate fixing device for disassembling the lower plate of the nuclear fuel assembly 2, and the fuel rod end gripping device 13 for fuel rod extraction in one head assembly 200. It is possible to precisely and safely grip the fuel rod by installing a link system 32 at the bottom of the impact trench section 14 so that the impact trench section 14 and the gripping device section 13 function organically. It is a very useful invention to install the gripping device so as to reduce the shielding work space and increase the work efficiency as well as to improve the safety of the work.

Claims (1)

In the head assembly 200 formed integrally with the take-out table 100, an impact trench portion 14 and a gripper portion 13 are mounted on the head assembly 200 and a link system is provided at the bottom of the impact trench portion 14. (32) to install the coil spring 34 on both sides of the impact trench portion 14 and the gear box 33 and the AC-type electric motor (30a) connected to one side of the impact trench portion 14 and In addition, the link system 32 installs an AC motor 30b on one side and fixes the ball screw 37 and the LM guide rail 36 to the AC motor 30b, and further includes the LM guide rail 36. On one side of the, the elm guide block 35 is fixed, but the elm guide block 35 is connected to the impact trench portion 14, and, holding the coil spring 29 on both sides of the gripping device 13, the gripping A ball screw 26 with a spring 28 is installed inside the device portion 13 and a slider 27 is opened on the ball screw 26. The AC installation motor 30 for operating the slider 27 is fixedly installed at one side of the gripper unit 13 and the spring 25 is inserted at one side of the gripper unit 13. Forming the gripping mechanism 23, the gripping mechanism 23 is connected to the ball screw 26, the remote dry withdrawal of the spent fuel rod, characterized in that the gripping mechanism support 24 is fixed to the outside of the gripping mechanism 23 Integrated head assembly for assembly dismantling and precision gripping of irregularly arranged fuel rods for processing.