JPS5924400B2 - Hold-down device in nuclear reactor fuel exchange equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hold-down device in a nuclear reactor refueling facility that positions a predetermined core element and performs a refueling operation by rotating a single-rotation plug and rotating a rotary arm in the hold-down device. In particular, the hold-down drive unit, which requires frequent maintenance and inspection because it is composed of a complicated mechanism, can be removed from the hold-down shaft, and the gripper equipped on the hold-down drive unit can be grasped with a handling gripper to hold it down. It is an object of the present invention to provide a novel hold-down device in which the hold-down shaft and the hold-down drive part are automatically disconnected by lifting the drive part, and which is advantageous for the operation of a nuclear reactor.

A single-rotation plug, rotary arm type refueling equipment as shown in FIG. 1 has already been put into practice and is well known.

That is, in the figure, 1 is a rotating plug placed at the top of the core,
2 is a hold-down device, which 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 rotary plug 1, and a gripper guide. tube 5, support member 6,
It is composed of a hold down arm 7, a door valve 8 provided at the upper end, etc.

The hold-down shaft 4 is operated by the drive unit 3 to move arrows A and B.
(Rotation, lifting and lowering operations are performed.)

On the other hand, the fuel exchanger 9 has a main body 1 consisting of a door valve 10, a gripper storage cylinder 11, a support frame 12, a hoist mechanism 13, a hoist cable 14, a gripper drive unit, and an outer cylinder.
5. It is composed of a gripper 17 installed at the tip of the main body 15 via a pantograph arm 16, and both the main body 15 and the gripper 17 are guided by the hold-down device 2 and suspended into the furnace, and the hoist mechanism 13, it is raised and lowered as shown by arrow C.

Note that the fuel exchanger is installed only when exchanging fuel, and at other times, the pantograph arm 16 is folded and the gripper 17 is installed.
is stored in the main body 15 and removed by pulling it out of the furnace.

On the other hand, it is well known that during fuel exchange, the gripper 17 is moved to a predetermined position in the furnace by rotating the rotary plug 1 and the hold-down device 20 times to perform the fuel exchange operation.

The hold-down device 2 in such single-rotation plug, rotary arm type fuel exchange equipment has the function of preventing adjacent fuel assemblies from floating up during fuel exchange, and also guides and positions the gripper 17 as described above. It is equipped with a hold-down drive unit 3 that rotates the hold-down shaft 4 so as to move the hold-down shaft 4 and moves it up and down within the working range inside the furnace.

The hold-down drive unit 3 with such functions is configured with a built-in complicated drive mechanism, and requires relatively frequent maintenance and inspection.
However, due to its configuration, it must be placed within the primary cooling system boundary.

Furthermore, the hold-down shaft 4 of the hold-down device 20 is installed as being inserted into the furnace without being removed from the furnace even when the fuel is not replaced.

For this reason, in the conventional hold-down device, the hold-down drive section 3 is constructed as a structure that is integrally coupled with the hold-down shaft 4.

However, maintenance, inspection, or troubleshooting of the hold-down drive section 3 requires considerably large-scale work, so if the conventional structure is used, there is a problem that the period during which the reactor operation is stopped will be extended.

In addition, since the drive unit 3 itself also needs to form a primary cooling system boundary against high-level radioactivity during nuclear reactor operation, its housing structure must also become complicated.

In view of this point, the present invention is capable of making the hold-down drive section removable from the hold-down shaft while the hold-down shaft is installed in the reactor, thereby facilitating maintenance and inspection even during reactor operation. During reactor operation, the hold-down drive unit can be easily configured as the primary cooling system boundary, and can be replaced with a reliable container, and the gripper attached to the hold-down drive unit can be grasped with a handling gripper. It is an object of the present invention to provide a novel hold-down device in which the hold-down shaft and the hold-down drive section are automatically uncoupled by lifting the hold-down drive section.

Next, the configuration of the present invention will be explained in detail based on illustrated embodiments.

First of all, FIG. 2 schematically shows the structure of the embodiment of the present invention, in which the hold-down shaft 4 is suspended within a preheating sleeve 18 equipped on the rotating plug 1, and further inside the shaft 4 is a reactor operating shaft. Shiyahei Plug 1 for preventing radioactivity during time
9 has been inserted.

This plug 19 is connected to the inner surface of the hold-down shaft 4 by a ball latte 20, and the ball latte 20 is connected to a gripping part 21 of the stiff plug 19 and lifted using a handling gripper (not shown). The ball latte 20 is configured to automatically come off.

Further, 22 and 23 are seals that maintain airtightness between the shield plug 19 and the hold-down shaft 4, and between the shaft 4 and the preheating sleeve 18, and are formed by, for example, doubling O-rings.

A pressurization/purge piping 24 is connected between the double seals 22 and 230 to supply sealing gas under pressure from the outside, so that airtightness can be maintained and checked.

On the other hand, the hold-down drive unit 3, which is connected to the upper end of the hold-down shaft 4 passing through the rotary plug 1, is installed via a support tube 25, and is composed of an airtight casing 26 with a flexible function and a detailed A drive mechanism 27, the structure of which will be described later (FIG. 5), and the drive mechanism 27 and the hold-down shaft 4.
It is equipped with a latch mechanism that serves as a Porlatte 28 that can be engaged and detached from the upper end portion 4a, and a grip body 29 that is installed at the upper end of the drive section 3 and to which a handling gripper (not shown) is coupled. It is configured.

Moreover, the ball clutch 28 and the gripping body 29 are linked together, so that when the gripping body 29 is grasped with a gripper and the drive unit 3 is lifted up, the ball clutch 28 is automatically released and can be removed from the hold-down shaft 4. It is configured to be operable.

Furthermore, the hold-down shaft 4 is raised and lowered via the ball latch 28 by a vertical drive mechanism built into the drive unit 3.
It is further rotated by a rotation drive mechanism.

To perform a fuel exchange from the state shown in the figure, place the plug handling machine on top of the door valve 8, pull out the damp plug 19, close the door valve 8 once, and install the fuel exchange machine 9 shown in Fig. 1. .

From this state, open the door valve 8, insert the main body 15 into the furnace, open the pantograph arm 16, and then open the gripper 17.
By setting the fuel in the guide tube 5, preparations for fuel exchange work are completed.

When refueling operations are completed and reactor operation is resumed,
Alternatively, when maintaining or inspecting the hold-down drive unit 3, the drive unit 3 is removed from the hold-down shaft 4 by releasing the ball latte 28 by lifting the gripper.

At this time, the hold-down shaft 4 remains inserted into the furnace, and its primary cooling system boundary is formed by the seals 22 and 23.

Furthermore, a third
A disturbance container 30, which constitutes the primary cooling system boundary as shown in the figure, is installed during the operation of the nuclear reactor.

This container 30 has an upper end 4a of the hold-down shaft 4.
A clamp 31 is provided to hold the hold-down shaft 4, and to bear the moment applied to the hold-down shaft 4 during an earthquake or the like.

In addition, FIGS. 4a and 4b show the hold-down drive unit 3 as described above.
This figure shows the procedure for inspecting and replacing the seal 23 attached to the hold-down shaft 4, which is still mounted on the furnace side, with the seal 23 removed.

In particular, since the seal 23 is attached to the hold-down shaft 4 to keep the inside of the furnace airtight, it is not possible to remove the seal 23 and inspect or replace it.

This can be accomplished by using a specially designed seal inspection tool as shown.

In other words, section 4 (a) in the left half of the figure shows that prior to the fuel exchange work,
Remove the container 30 shown in FIG. 3 and check the seal inspection device 40.
Shown with the attached.

This seal inspection device 40 has a lower part 4 equipped with an expansion seal 42 and a hold-down shaft holding mechanism 43 serving as a screw mechanism.
1 and an upper part 44 provided with an inflatable seal 45.

The inflatable seals 42 and 45 are hollow ring-shaped seals that are normally stored in a contracted state in a groove, and when the inside is pressurized, they extend inward to maintain airtightness with the mating surface.

The expansion seals 42 and 45 are connected to independent pressurization lines, and the seal inspection device 40 is connected to a pressurization-purge piping for replacing the inside with seal gas.

In the state shown in FIG. 4a, first, the upper expansion seal 45 is pressurized to make the gap between the hold-down shaft 4 and the seal inspection device 40 airtight, and the space between them is replaced with seal gas.

Next, the lifting gripper 46 is engaged with the upper part of the hold-down shaft 4, and the hold-down shaft 4 is pulled up as shown by the arrow to the position shown in FIG. 4 on the right half.

Here, the hold-down shaft holding mechanism 43 is operated to engage with the groove 47 provided in the hold-down shaft 4 to support the weight of the hold-down shaft 40.

In this state, the inflatable seal 42 at the lower position is pressurized to form a seal there, and then the gripper 46 is removed, and the inside of the seal inspection device 40 is returned to air, and the inflatable seal 42 is
5 and pull out the upper part 44 of the seal inspection device upward.

FIG. 4 shows this state, in which the seal 23 is exposed to the outside and can be easily inspected and replaced.

After inspecting and replacing the seal 23, reverse the above procedure to return to the state shown in FIG. 4a, and remove the seal inspection device 40.

By the above procedure, inspection and replacement of the seal 23 can be performed while maintaining the boundaries of the primary cooling system.

FIG. 5 shows a detailed structure of the hold-down drive section 3 described in FIG. 3, and the same reference numerals as in FIG. 3 indicate the same members.

In the figure, a shearing material 51 is built into the airtight casing 26 and surrounds the drive mechanism 27.

Grip rods 52 are attached to the grip body 29 at several locations on the circumference, and a groove 53 is provided near the lower end of the grip rods 52 .

When the gripping body 29 is grabbed by the handling gripper and pulled upward from the state shown in the figure, the groove 53 comes to the position of the ball latte 28, and the ball latte 28, which had been restrained by the gripping rod 52, is released. At the same time, a nut and washer 54 attached to the lower end of gripping rod 52 lifts support member 55.

Ball screw nuts 56 are attached to the support member 55 at several locations on the circumference, and the rotary frame 59 is lifted up via a nut and washer 58 attached to the lower end of a ball screw 57 screwed into the support member 55.

This rotating frame 59 supports a cross roller bearing 60 that supports loads in the radial and axial directions. The entire hold-down drive section 3 can be lifted.

At this time, since the ball latch 28 is released, the hold-down shaft 4 is disengaged from the support member 55 and remains in the same position.

FIG. 5 shows a state in which the hold-down shaft 4 is lowered to its lowest limit, and from this state the hold-down drive unit 3 can be removed as described above.

On the other hand, when driving the hold-down shaft 4 upward, by rotating the ball screw screw 57, the ball screw nut 56, the support member 55, and therefore the hold-down shaft 4 connected by the ball latte 28 are lifted upward. It will be done.

At this time, the ball screw 57 is supported by the rotating frame 59.

Further, the rotating frame 59 is connected to the shoulder 66 of the casing 26 via a cross roller bearing 65 fixed by a spacer 64.
It is supported by

The ball screw 57 is supported by a rotating frame 59 with a radial bearing 67 at its lower end and a radial-thrust bearing 68 at its upper end.

69 is a bearing holder for the bearing 60.

Furthermore, a pinion 70 is attached to the upper end of the ball screw screw 57.
is attached and meshes with the internal gear 71.

A large bevel gear 72 is fixed to this internal gear 71,
It is supported by the casing 26 via a bearing 62.

The large bevel gear 72 is connected to the small bevel gear 73 and the casing 26 via a sealed bearing assembly 74.
Connected to an external drive source.

Note that the small bevel gear 73 and the bearing assembly 74 can be pulled out as a unit for easy maintenance and inspection.

The bending moment that acts on the hold-down shaft 4 during fuel changes or earthquakes is due to the slide roller bearing 75.76
This load is carried by the casing 26 via bearings 60 and 65, respectively.

Hold-down shaft 4 engaged with roller bearing 15
Although the outer surface shape is a circular cross section as shown by the chain line S1 in the figure, the portion that engages with the roller bearing 76 is defined as an irregular polygon as also shown by the chain line S2.

This is to transmit the torque for rotating and positioning the hold-down shaft 4, and the inner diameter of the large bevel gear 77 that holds the roller bearing 76 is also formed into a corresponding irregular polygonal shape.

The large bevel gear 77 is a small bevel gear 78, and the bearing assembly 7
It is connected to an external drive source via 9.

To drive the hold-down shaft 4 up and down, a small bevel gear 7 is used.
If the small bevel gear 73 is driven with the rotating frame 5 fixed,
9 remains fixed, only the ball screw 57 rotates to move the support member 55 up and down, and therefore the hold-down shaft 4 is moved up and down via the ball latte 28.

On the other hand, in order to rotate the hold-down shaft 4, the small bevel gear 7
If 3 and 78 are driven in the same direction with the same amount of rotation, the ball screw 57 will not rotate and only the rotating frame 59 will rotate.
The hold-down shaft 4 is rotationally driven via a large bevel gear 77 whose inner diameter surface has an irregular polygonal shape.

Note that the above-mentioned drive mechanism is just one specific example, and the rotational up/down operation of the hold-down shaft 4 and the engagement/disengagement operation of the latch mechanism 28 can be performed by a drive mechanism other than the above-mentioned mechanism.

As is clear from the description of each of the figures above, according to the present invention, a hold-down shaft is inserted into the furnace, and a hold-down drive is provided as a means to be connected to the upper end of the hold-down shaft located outside the furnace. An interlocking type in which the hold-down shaft and the hold-down drive unit are automatically uncoupled by connecting the hold-down shaft and the hold-down drive unit by grasping the grip body with a handling gripper and lifting the hold-down drive unit. It is equipped with a latch mechanism.

Therefore, maintenance and inspection of the hold-down drive section can be performed by removing it from the hold-down shaft and performing maintenance and inspection work at another location.

This simplifies the maintenance and inspection work of the hold-down drive unit, and is advantageous in that it shortens the period during which the nuclear reactor is shut down.

In addition, in order to form a primary cooling system boundary at the hold-down drive section and door valve even during reactor operation, where the radioactivity level is high, conventional drives are guided outward through the airtight casing, such as bearing assemblies. The seal structure of the shaft becomes extremely complicated.

In contrast, in the present invention, as shown in Figure 3, the hold-down drive unit, door valve, etc. are removed during reactor operation, and a container with a simple structure and reliable performance is used as the primary cooling system boundary. Can be replaced.

As described above, the present invention can provide a holddown device that is extremely advantageous for nuclear reactor operation and maintenance and inspection of the holddown drive section.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a single-rotation plug and rotary arm type fuel exchange equipment, Fig. 2 is a schematic cross-sectional view schematically showing the main parts of a hold-down device based on an embodiment of the present invention, and Fig. 3 is Cross-sectional view of the container installed during reactor operation,
FIGS. 4a and 4b are explanatory diagrams showing the procedure for seal inspection of the hold-down shaft, and FIG. 5 is a detailed enlarged view of the hold-down drive section in FIG. 2. 1: Rotating plug, 2: Hold down device, 3: Hold down drive unit, 4: Hold down shaft, 6 Ni hold down arm, 9: Fuel exchanger, 26 Airtight casing of the two hold down drive unit, 27: Drive mechanism , 28: latte mechanism, 29: gripping body, 52: gripping rod for operating the latch mechanism that connects and connects the latte mechanism and the gripping body.

Claims (1)

[Claims] 1 In rotary arm type refueling equipment that consists of a fuel exchanger installed on a single-rotation plug of a reactor and a hold-down device that guides and positions the fuel exchanger's gripper, it is installed outside the reactor and inserted into the reactor. A hold-down drive unit that rotates and lifts the hold-down shaft is coupled to a gripping body equipped on the hold-down drive unit as a means for coupling the drive mechanism in the drive unit and the hold-down shaft. and an interlocking operation type latch mechanism that automatically releases the connection between the hold-down shaft and the hold-down drive unit by holding down the holding body with a handling gripper and lifting the drive unit. A hold-down device in a nuclear reactor refueling facility.