JPH0367240B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a nuclear reactor fuel that is positioned in a predetermined core element and used for fuel exchange equipment by the rotation of a single-rotation plug and the rotation of a rotating arm of a hold-down device. The present invention relates to a hold-down device that allows a hold-down drive section to be easily removed from a hold-down shaft in replacement equipment.

[Technical Background of the Invention] Refueling equipment consisting of a single-rotating plug and a rotating arm-type hold-down device has already been implemented and is known. FIG. 1 shows an example of its configuration. In the figure, reference numeral 1 indicates a single-rotation type rotary plug disposed at the upper part of the reactor core, and reference numeral 2 indicates a hold-down device. The hold-down device 2 includes a hold-down drive unit 3 installed outside the furnace above the rotary plug 1, a hold-down shaft 4 inserted into the furnace through the sleeve 1a of the rotary plug 1, and a gripper guide tube 5.
, a gripper guide tube support member 6 , a hold-down arm 7 , a door valve 8 provided at the upper end of the hold-down drive unit 3 , and the like. The hold-down shaft 4 is rotated and raised and lowered as indicated by arrows A and B by the hold-down drive unit 3.

The fuel exchanger 9 also includes a casing 11 that houses a fuel exchanger main body 10 that moves up and down through a door valve 8, a sealing device 12, and a fuel exchanger main body 1.
It is comprised of a hoisting mechanism 13 for moving the fuel exchanger up and down, a rope 14, a gripper 16 connected to the tip of the main body 10 of the fuel exchanger via a pantograph arm 15, and the like. The fuel exchange device main body 10 and the gripper 16 are guided by the hold down device 2 and suspended into the furnace, and are raised and lowered by the hoisting mechanism 13 as shown by arrow C.

The fuel exchanger 9 is installed only when exchanging fuel, and at other times, the pantograph arm 15 is folded, the gripper 6 is stored in the main body 10, and the gripper 6 is pulled out of the furnace and removed. Furthermore, during fuel exchange, the gripper 16 is moved to a predetermined position within the furnace by the rotation of the rotary plug 1 and the hold-down device 2, and the fuel is exchanged.

As described above, the hold-down device 2 in the single-rotation plug rotary arm type fuel exchange equipment not only functions to prevent adjacent fuel assemblies from floating up during fuel exchange, but also guides and positions the gripper 16. It is equipped with a hold-down drive unit 3 that rotates a hold-down shaft 4 and moves it up and down within the working range within the furnace. This hold-down drive unit 3 has a built-in complicated drive mechanism and requires relatively frequent maintenance and inspection, so it is installed outside the rotary plug 1 as shown in the figure. For some reason, it has to be placed within the primary cooling system boundary. In addition, hold down device 2
The hold-down shaft 4 is installed inside the furnace without being removed from the furnace even when the fuel is replaced.

[Problems in the Background Art] However, the conventional hold-down drive unit requires considerably large-scale work to perform maintenance, inspection, or troubleshooting, which lengthens the period during which the reactor is out of operation. The problem was that the primary cooling system boundary had to be created to protect against high-level radioactivity during reactor operation, so the shielding structure had to be complicated.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems in the background art, and it is possible to remove the hold-down drive unit from the hold-down shaft while the hold-down shaft is installed in the furnace. The purpose of the present invention is to provide a new hold-down device that can be easily maintained, inspected, and repaired.

[Summary of the Invention] The hold-down device in the nuclear reactor fuel exchange equipment of the present invention includes a hold-down shaft inserted into a rotary plug so as to be rotatable and movable up and down, and a gripper inserted into the reactor through the hold-down shaft and a gripper at the lower end. In the hold-down device for nuclear reactor fuel exchange equipment, the hold-down device includes a fuel exchange device main body, and a hold-down drive unit mounted on the rotating plug, wherein the hold-down drive unit includes a rotating electric motor provided outside the sleeve. and a vertical movement driving electric motor, and a transmission mechanism that transmits the rotational force of these electric motors to the hold-down shaft to rotate and vertically move the hold-down shaft, and the hold-down shaft is inserted into the hold-down shaft. The present invention is characterized in that a ring-shaped member is fixed to the upper surface of the sleeve of the rotary plug to airtightly close the space between the sleeve and the hold-down shaft.

[Embodiments of the Invention] Hereinafter, the configuration of the present invention will be described in detail based on illustrated embodiments.

In FIG. 2, the hold-down shaft 4 is suspended in a sleeve 1a provided on the rotary plug 1,
Further, within the shaft 4, a fuel exchange device main body 10 for exchanging fuel in the core is suspended from a hoisting mechanism (not shown) and is housed so as to be vertically movable and rotatable.
The sleeve 3a of the hold-down drive unit 3 is fixedly supported on the sleeve 1a of the rotary plug 1 with bolts 3b, etc., and a door valve 8 and a lift drive device (not shown) are installed above the sleeve 3a.

The holddown drive unit 3 includes a rotation mechanism 20 that rotates the fuel exchanger main body 10 during fuel exchange, and a gripper guide that protrudes from the holddown shaft 4 to prevent other core components from floating when handling the core components. A vertical movement drive mechanism 30 for pushing up the cylinder 5 is provided.

The swing mechanism 20 includes an electric motor 21 , a speed reducer 22 , a lower bevel gear 23 , a key 24 , a bearing 25 , and a swing bearing 26 . The vertical movement drive mechanism 30 is composed of an electric motor 31, a reduction gear 32, an upper bevel gear 33, a rotating ring 34, a support ring 35, and wheels 36. keys 37 are attached.

Further, rings 41 and 42 are fixed to the step portion and the upper end portion of the hold-down shaft 4 with bolts 43 and 44, respectively. As shown in FIG. 3, an O-ring 45 is arranged between the upper surface of the step, the ring 41 and the sleeve 3a and the sleeve 1a to form a double seal, and the pressurized gas introduced through the vent hole 46 allows the furnace to It is designed to isolate the inside and outside air.
As shown in FIG. 4, the lower surface of the support ring 35 is an inclined surface 35a, and the wheels 36 roll in contact with this inclined surface, and the upper bevel gear 33 rotates the rotating ring 34. Then, the fuel exchange device main body 10 moves up and down in the direction of arrow B.

Next, the operation of the hold-down device in the reactor fuel exchange equipment of the present invention configured as described above will be explained. When exchanging fuel, etc. in a nuclear reactor, a fuel exchange device main body 15 is transferred from a hold-down drive unit 3 attached to the upper surface of the sleeve 1a of the rotary plug 1 into a hold-down device 2 installed in the reactor. is lowered and the gripper guide cylinder 5 is rotated to the position of the core component to be replaced. In this case, the sleeve 3a of the hold-down drive unit 3
Drives an electric motor 21 attached to the outside, transmits its rotational force to the lower bevel gear 23 via the reduction mechanism 24, and rotates the hold-down shaft 4 until the gripper guide cylinder 5 at its tip reaches a predetermined position. .

Next, in order to prevent the adjacent core components from floating up, the gripper guide cylinder 5 at the tip of the hold-down shaft 4 is lowered to reduce the gap between the gripper guide cylinder 5 and the top of the core components. In this case, when the electric motor 31 attached to the outside of the sleeve 3a is driven, its rotational force is transmitted to the upper bevel gear 33 via the deceleration mechanism 32, and the rotating ring 34 of the vertical drive mechanism rotates. This rotation causes a plurality of wheels 36 attached to the upper surface of the rotary ring 34 to roll, and the support ring 35, to which the entire weight of the hold-down device 2 is applied, is lowered. Note that since guide keys 37 are attached to the outer periphery of the support ring 35 at several locations, the support ring 35 does not rotate but only moves downward.

After positioning the gripper 16 in this manner, the core component is gripped by the gripper 16 and stored in the gripper guide tube 5. Next, raise the hold-down shaft 4 to its original position by reversing the steps above,
The gripped core component is also inserted into the next loading position (for example, an in-core relay device) by performing a pivoting operation. Fuel exchange is performed by repeating these operations.

Since the above-mentioned turning mechanism and vertical movement drive mechanism are used every time fuel is replaced, gears, bearings, etc. are easily damaged, and it is necessary to be able to replace them when damaged. According to the present invention, when the hold-down shaft 4 is lowered by the vertical movement drive mechanism 30 until the ring 41 hits the sleeve 1a as shown in FIG.
A double seal is formed by the ring 45, and sealing gas is supplied under pressure to the middle part of the ring 45 through the vent hole 46, so that the inside of the furnace is isolated from the outside air. Furthermore, if the upper part of the door valve 8 on the hold-down drive unit 3 is removed, the parts inside the sleeve 3a can be taken out upwards because they have a stacked structure. Since each drive system of the mechanism can be pulled out laterally from the outside, disassembly and assembly can be easily performed. Note that during such maintenance, the fuel exchange device main body 10 is pulled out from the hold-down device, and the fuel exchange device main body 1
The opening into which 0 was inserted is closed by a plug (not shown). Furthermore, in the event of a nuclear reactor recriticality accident, the ring 41 attached to the hold-down shaft 4 comes into contact with the inward protrusion 3c of the sleeve 3 to limit its upward movement, thereby preventing it from turning into a missile.

[Effects of the Invention] As described above, in the hold-down device in the fuel exchange equipment of the present invention, transmission mechanism parts such as gears of the drive mechanism for swinging and vertical movement of the hold-down device, which are frequently used for each fuel exchange, are used. As a countermeasure against malfunctions, the structure of the drive section is stacked, so that disassembly and inspection and reassembly can be easily performed in the event of a failure of the transmission mechanism of the drive system. Moreover, during disassembly, the hold-down shaft is sealed to the sleeve by a sealing mechanism, and in the event of a nuclear reactor recriticality accident, the inward protrusion of the sleeve can prevent the hold-down shaft from turning into a missile. safety will be improved. As described above, according to the present invention, it is possible to obtain a hold-down device in a nuclear reactor fuel exchange facility that allows easy maintenance and inspection in the event of a failure of the hold-down device.

[Brief explanation of drawings]

Fig. 1 is an overall view of a conventional single-rotation plug rotary arm type refueling equipment, Fig. 2 is a vertical sectional view showing the main parts of an embodiment of the hold-down device of the present invention, and Fig. 3 is a hold-down of the present invention. FIG. 4 is a vertical cross-sectional view showing details of the installation part of the device, and FIG. 4 is a vertical cross-sectional view showing details of the drive mechanism for vertical movement of the hold-down device in the present invention. DESCRIPTION OF SYMBOLS 1...Rotary plug, 2...Hold down device, 3...Hold down drive unit, 4...Hold down shaft, 5...Gripper guide tube, 6...Gripper guide tube support member, 7...Hold down arm , 8...Door valve, 9...Fuel exchange machine, 10
... Fuel exchange device main body, 11 ... Casing, 1
2... Sealing device, 13... Hoisting mechanism, 14...
Rope, 15... Pantograph arm, 16...
...Gritzpa, 20...Swivel mechanism, 21, 31...
Electric motor, 22, 32...Reduction gear, 23...Lower bevel gear, 24, 37...Key, 25...Bearing, 26
... Swivel bearing, 30 ... Vertical movement drive mechanism, 33
...Upper bevel gear, 34...Rotating ring, 35...
Support ring, 36...Wheel, 41, 42...Ring, 45...O ring, 46...Vent hole.

Claims (1)

[Scope of Claims] 1. A hold-down shaft inserted into the rotary plug so as to be rotatable and movable up and down; a fuel exchange device main body inserted into the furnace through the hold-down shaft and equipped with a gripper at the lower end; In a hold-down device for a nuclear reactor fuel exchange facility, the hold-down drive unit includes a swing electric motor and a vertical movement drive electric motor installed outside the sleeve, and a The hold-down shaft is provided with a transmission mechanism that transmits rotational force to the hold-down shaft and rotates and moves the hold-down shaft up and down. A hold-down device for a nuclear reactor fuel exchange facility, characterized in that a ring-shaped member is fixed to airtightly close a space between the hold-down shaft and the hold-down shaft. 2. The transmission mechanism includes a lower bevel gear attached to the outer periphery of the hold-down shaft via a key and transmitting the rotational force of the turning electric motor to the hold-down shaft, and a rotating ring rotatably attached to the outer periphery of the hold-down shaft. A wheel provided at the upper end of the rotating ring, a support ring having an inclined surface that contacts the wheel and supporting the load of the hold-down shaft, and an upper cover that transmits the rotational force of the vertical drive motor to the rotating ring. A hold-down device in a nuclear reactor fuel exchange facility according to claim 1, comprising a gear.