JPS63214696A - Fuel gripper for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor fuel gripping tool that is incorporated into a fuel exchanger installed in a nuclear power plant.

(Prior Art) At nuclear power plants, fuel rods are replaced using fuel exchange machines during periodic inspections of nuclear reactors. This refueling work involves taking spent fuel rods out of the reactor, moving them to the fuel pool, and loading new fuel rods into the reactor. I am trying to rearrange the location within.

By the way, as shown in FIG. 3, the fuel exchanger 1 is connected to a spent fuel pool 2. Reactor well pool 3. A reactor pressure vessel 7 is provided so as to be able to run freely on the fuel exchange floor 5 while straddling the upper part of the dryer separator pool 4, is located below the reactor well pool 3, and is housed in the reactor containment vessel 6. The fuel rods 9 arranged in the reactor core 8 are gripped by a fuel gripper 1°, taken out of the reactor, and put into the spent fuel storage rack 11 of the spent fuel pool 2.

The fuel rods 9 are finally carried into the spent fuel transfer cask 18 using the fuel gripper 1° and transferred.

Next, regarding the fuel appliance 10 and the fuel exchanger 1, the fourth
This will be explained with reference to the figures.

The fuel appliance 10 includes a plurality of masts 17a having different diameters.

17b, . . . , 17e telescopically, that is, a main mast portion 12 formed by telescopically housing the mast 17a, and a grapple head 13 provided at the tip of the mast 17a. It is configured to be removably clamped. The mast 17a at the lowest stage is supported via a wire 14 by a mast drive device 16 provided in the fuel exchanger 1 so as to be able to move up and down.

Note that 15.16b is a pulley.

Further, the space between adjacent stages of the main body mast portion 12, for example between the mast 17a and the mast 17b, is not particularly airtight.

(Problems to be Solved by the Invention) By the way, in the conventional fuel appliance 10, when raising and lowering the grapple head 13, a specific mast of the main body mast portion 12, for example, the mast 17c,
In order to prevent the fuel appliance 10 from hitting hard, the lifting speed of the fuel appliance 10 is reduced near the mast joint. That is,
Near the mast joints, the fuel appliance 10 is decelerated from its maximum speed to about 20% to prevent large impact forces from acting on the masts at each stage when going up and down.

However, during refueling work, approximately 25% of the hundreds of fuel rods arranged in the reactor core are replaced and the remaining fuel rods are relocated, so the operation of the fuel equipment is affected. It takes up a large portion of your time.

Therefore, in order to shorten the time required for refueling work, it is necessary to increase the lifting speed of the fuel equipment, but since the speed of this fuel equipment is limited for the reasons mentioned above, the time required for refueling work is There are limits to how much time can be reduced.

Additionally, the main body mast portion 12 is supported by wires 14, but since fuel containing radioactive materials is handled, it has recently been considered that reducing the number of wires to two would improve safety. ing. However, this method is useless if the mast drive 16 fails.

Furthermore, there are problems with the movement of spent fuel to the transfer cask 18 as described below.

That is, as shown in FIG. 3, the main mast part 12 of the fuel equipment 10 needs to reach from the fuel exchange floor 5 to the reactor core 8, and also needs to be at the fuel exchange floor level so that it can be moved freely when stored. You need to roll it up more.

For example, when lowering, the fourth stage mast 17d1 the third stage mast 17C1 the second stage mast 17b1 the first stage mast 17a
The masts extend in this order from large to small diameter masts. Conversely, when hoisting, the first stage mast 17a1 the second stage mast 17b1 the third stage mast 17C1 the fourth stage mast 17d
The mast is then stored from a small diameter to a large diameter mast.

Spent fuel rack 1 using such fuel equipment 1G
FIG. 5 shows a state in which the fuel rods 9 have been loaded onto the spent fuel rack 1. The upper portions of the fuel rods 9 are exposed above the spent fuel rack 11, and the fuel rods 9 can be loaded without any problem.

However, when loading the spent fuel transfer cask 18, the fuel rods 9 must be loaded so deep that the upper part is hidden. The section 12 is not fully extended and the first stage mast 17a with the grapple head 13 is still housed within the second stage mast 17b.

On the other hand, the spent fuel transfer cask 18 is divided by a grid of minimum dimensions necessary to accommodate the fuel rods 9, and within the main mast portion 12, it is difficult for the first stage mast 1aL to pass through the grid. I can't. For this reason, conventionally, as shown in FIG. 6, the large-diameter third-stage mast 17C, fourth-stage mast 17d, and fifth-stage mast 17e are fixed by inserting mast fixing pins 19 in the retracted state for use and fuel transfer. cask 1
When loading the fuel rods 9 into the first stage mast 17a, the first stage mast 17a
It is designed so that it can be used in a fully extended state from the stage mast 17b. Inserting this mast fixing pin 19 is a troublesome task.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the masts of adjacent stages from strongly hitting each other near the mast joints when moving each mast of the main mast part, and to raise and lower the grapple head. It is an object of the present invention to provide a fuel gripping tool which greatly reduces the time required for fuel exchange and reduces the work time required for fuel exchange.

Furthermore, another object of the present invention is to prevent accidents of falling fuel containing radioactive materials that may occur due to cutting of wires supporting the main mast section or malfunction of the mast drive device. is to provide fuel appliances.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a main body mast portion which is configured to be extendable and contractible by concentrically arranging a plurality of masts having different diameters; A fuel gripping tool for a nuclear reactor, comprising a drive device for raising and lowering a mast located at the center thereof, and a grapple head provided at one end of the mast located at the center for gripping fuel in the reactor. , an airtight part is provided between the plurality of masts, a pressure adjustment device that can individually adjust the pressure of the airtight part is provided, and the plurality of masts are expanded and contracted by the pressure adjustment device to raise and lower the fuel in the reactor. It is characterized by being configured as follows.

(Function) In the fuel gripping tool configured as described above, an airtight part is provided between each stage of a plurality of masts, so by controlling this pressure with a pressure regulator, the damper is activated when the mast moves up and down. This function prevents impact between the masts, allowing the masts to be raised and lowered at high speed. Also, wire breakage,
Even in the event of a malfunction of the mast drive device, by adjusting the pressure in the airtight part, you can prevent the mast from falling freely.
It can also be driven from a free stage.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of an embodiment of the present invention. As shown in the figure, the fuel appliance of the present invention includes a main body mast portion 12 which telescopically accommodates a plurality of masts 21a, 21b, 21c, .
Grapple head 1 as a clamp member provided at the lower end of the lowermost mast 21a of this main body mast portion 12
3. Airtight portions 31a and 31b are airtight between adjacent masts.

31C2... are provided.

One end of a wire 23 is fixed to the upper end of the lowermost mast 21a, and the other end of the wire 23 is fixed to a mast drive device 25 via a pulley 24. Air hoses 28a, 28b, . . . are connected to the airtight portions between adjacent mast stages, and are fed out by hose reels 26a, 26b, . Each air hose 28a.

The other end of 28b... is connected to the switching valves 27a, 27b..., where the airtight parts 31a, 31b, 31G...
It is used to maintain, increase, and reduce the pressure of...

This switching 'j927a, 27b, . . . is controlled by the control device 29. Further, a drive system failure detection circuit 30 that detects a failure of the mast drive device 25 or a cable breakage is connected to the mast drive device 25, and this signal is sent to the control device 2.
It is connected to 9.

Next, the operation of this embodiment will be explained.

In FIGS. 1 and 2, when the fuel appliance is raised or lowered, the switching valves 27a, 27b are
, 27c... are left open to the atmosphere. Thereafter, the grapple head 13 is raised and lowered by driving the wire drum of the mast drive device 25.

Here, winding up and winding down will be explained respectively.

First, when lowering, the fourth stage mast 21d is fixed, so the first stage mast 21a, the second stage mast 21
b. The third stage mast 21G begins to descend.

As the descent progresses, the pressure in the airtight portion 31c between the fourth stage mast 21d and the third stage mast 21C increases to the air tube 28.
It becomes expensive because the exhaust from C cannot catch up.

Therefore, the second stage mast 21b starts to descend before the third stage mast 21G is completely extended from the fourth stage mast 21d. In the same way, it descends to the lowest mast 21a. At this time, the masts of each stage that were not fully extended will slowly extend due to the damper effect. Therefore, the impact that occurs when the mast is fully extended is alleviated.

Next, when hoisting up, the first stage mast 21a is first hoisted up. At this time, the first stage mast 21a and the second
The pressure in the airtight portion 31a between the stage masts 21b becomes negative because the intake air cannot catch up. Therefore, the storage of the second stage mast 21b starts before the first stage mast 21a is completely stored in the second stage mast 21b. In the same way, it is rolled up until it is fully retracted. At this time, each stage of the mast that could not be completely stowed will be slowly stowed due to the sufficient damping effect.

As mentioned above, even if the mast is operated at a constant speed during hoisting or lowering, large shocks can be avoided because a damper effect occurs when each stage mast is fully extended or retracted. .

Next, the case of wire breakage and mast drive failure will be described.

When a break in the wire 23 or a failure occurs in the mast drive device 25, the failure is detected by the drive system failure detection circuit 30, and the switching valves 27a, 27b, 27G,
Issues a command to pressurize... Therefore, the airtight area 3 between the masts
1a, 31b... become high pressure, each mast 21a,
21b, 21c... can be pushed up to prevent the mast from falling.

Roughly speaking, the airtight parts 31a, 3Tb, 3tc between the respective masts 21a, 21b, 21c, 21d are connected to the switching valves 27a, 2.
7b.

Since the pressure can be freely adjusted using 27c, the mast can be raised and lowered in any order.

Furthermore, when loading fuel into the spent fuel transfer cask 18, it can be dropped from the first stage mast 21a by pressurizing it with the switching valves 27b and 27c and opening the switching valve 27a.

[Effects of the Invention] As explained above, according to the present invention, when the mast is raised and lowered, the airtight portion acts as a damper, so that it is possible to suppress the occurrence of impact at the joint, so that the impact near the joint can be suppressed. The fuel gripper can be raised and lowered at high speed. Therefore, the fuel exchange time can be greatly shortened, which improves the reactor's availability and
This will lead to improving the operating economy of nuclear power plants. In addition, in the event of a cable break or malfunction of the mast drive device, high reliability can be expected as this can be detected and high pressure applied to the airtight area to prevent the mast from falling. In addition, by adjusting the pressure in the airtight part, it is possible to change the operating order of the mast during lifting and lowering, so fuel can be loaded from the bottom of the mast to the spent fuel phase cask, which must be lowered before use. There is no need for troublesome advance preparation during work.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the main body mast portion of FIG. 1, FIG. Figure 4 is a configuration diagram of a conventional fuel gripper, Figure 5 is a diagram of fuel being loaded into a used fuel storage rack using a conventional fuel gripper, and Figure 6 is a conventional fuel gripper using a mast fixing pin. FIG. 3 is a diagram showing a state in which fuel is loaded into a spent fuel phase cask. 1... Fuel exchange machine 2... Spent fuel pool 3... Reactor well pool 4... Dryer separator pool 5... Fuel exchange floor 6... Reactor containment vessel 7
Reactor pressure vessel 8 Reactor core 9 Fuel rod 10 Fuel gripper 11 Spent fuel storage rack 12 Main mast portion 13 Grapple head 14 ...Wire 17...Mast 1
8... Spent fuel transfer cask 19... Mast fixing pin 21... Mast 23.
... Wire 24 ... Pulley 25 ... Mast drive device 26 ... Hose reel 27 ... Switching valve 28 ... Air hose 29 ... Control device 30 ... Failure detection circuit 31 ... Airtight Department (8733) Agent Patent Attorney Yoshiaki Inomata (and 1 others)
Figure 1 Figure 2 Figure 3-j Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) A main body mast part that is configured to be extendable and retractable by concentrically arranging multiple masts with different diameters, a drive device that raises and lowers the mast located in the center, and a A fuel gripping tool for a nuclear reactor including a grapple head provided at one end to grip fuel in the reactor, wherein an airtight part is provided between the plurality of masts, and the pressure of this airtight part can be adjusted individually. A pressure adjustment device is installed,
A fuel gripping tool for a nuclear reactor, characterized in that the pressure regulating device is configured to extend and contract a plurality of masts to raise and lower fuel within the reactor.