JPS582632B2 - Refueling equipment for nuclear reactors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fast reactor that uses liquid metal sodium as the primary coolant. Regarding the improvement of exchange equipment, especially the shaft seal device that forms the primary cooling system boundary for fuel exchange machines, the aim was to reduce sodium accumulation, maintain stable sealing function for a long period of time, and improve reliability. There is a particular thing.

A fuel exchanger, especially a fuel exchanger that combines a single rotation plug and a pantograph mechanism, has a complex lower structure. Effective seals are cumbersome.

For this purpose, a fuel exchanger is generally constructed in such a manner that the main body of the fuel exchanger is housed in an airtight container and installed on a rotating plug as shown in FIG.

That is, in FIG. 1, 1 is a rotary plug, 2 is a hold-town device installed protruding into the furnace, and 3 is a fuel exchanger.

The hold-down device 2 includes a hold-down shaft 4 inserted into the furnace through the rotary plug 1, and a support arm 5 attached to the shaft 4.
It consists of a gripper guide cylinder 6 supported via a gripper guide cylinder 6, a hold-down drive part 7 provided at the upper end of the shaft 4, and a shielding valve for a rotary plug entrance/exit hole, which serves as, for example, a door valve 8 provided above the hold-down drive part 7.

On the other hand, the fuel exchanger 3 is guided by the board-down shaft 4, passes through the rotary plug 1 and the door valve 8, and is inserted into the furnace.The fuel exchanger 3 is supported at the tip of the outer cylinder 9 via a panda graph rock structure 10. a fuel exchanger main body comprising a gripper 11, a driving section 12 which houses the opening/closing mechanism of the claws in the grip 11 and the opening/closing mechanism of the pantograph mechanism 10 and is installed at the top of the outer cylinder 9; a hoist mechanism 13; and a winding drum 14. , wire robe or chain for hanging15
Each of these parts has a door valve 1 at the bottom.
It is stored in a long airtight container 1γ equipped with 6.

In such a conventional configuration, the airtight container 17 has a sufficient shielding function against the radioactivity of the cover gas that enters from inside the furnace during fuel exchange, and also has a sufficient shielding function when the main body of the fuel exchanger is pulled out of the furnace. It is also necessary to have a sufficient shielding function against the radioactivity of the sodium adhering to the outer cylinder 9 and the gripper 11, which had been immersed below the sodium liquid level in the furnace.

As a result, the weight of the airtight container 17 becomes extremely large, which places a significant burden on the design of the furnace body, especially the rotary plug, which takes earthquake-resistant design into consideration.

From this point of view, it has been proposed to omit the long airtight container 17 in FIG. 1 and instead surround the outer cylinder of the fuel exchanger and include a shaft sealing device.

This shaft sealing device is provided integrally with another door valve coupled to the upper part of the door valve 8 in FIG. It is located exposed to the outside.

Such a shaft sealing device is constructed with a sealing mechanism that has the function of preventing leakage of the in-furnace bar gas and the function of wiping off sodium adhering to the outer cylinder portion inserted below the liquid level in the furnace when it is pulled out of the furnace. There is.

Therefore, when the fuel exchanger is installed on the rotary plug and fuel is exchanged, the boundary of the primary cooling system is formed by the shaft sealing device, making it possible to omit the most airtight container.

On the other hand, with the above configuration, rather than removing the fuel exchanger from the furnace side during operation of the furnace or during maintenance and inspection of the fuel exchanger, the handling cask is attached to the top of the door valve and the fuel exchanger body is pulled up into the handling cask during fuel exchange. The entire outer cylinder of the rockfish body will pass through the shaft sealing device.

For this reason, although the seal structure is equipped with a sodium wiping section, a large amount of sodium adhering to the outer cylinder, which has been inserted below the sodium liquid level in the furnace, can be removed from the seal mechanism of the shaft sealing device. It will be wiped off and deposited.

However, as is well known, metallic sodium solidifies at room temperature and is oxidized, which causes the sealing mechanism to deteriorate and the smooth sealing surface to become rough, causing it to lose its sealing function within a short period of time. There is a fear.

For this reason, the shaft seal device described above has the advantage of being able to omit the airtight container shown in Figure 1, but on the other hand, it is difficult to maintain a stable sealing function for a long period of time due to the accumulation of a large amount of sodium, making it difficult to put it into practical use. It's difficult.

In view of these points, the present invention has the advantage of omitting the conventionally used airtight container, and also skillfully prevents a large amount of sodium from accumulating when the main body of the fuel exchanger is taken out of the furnace, thereby stabilizing the sealing function. It is an object of the present invention to provide a fuel exchange device equipped with a shaft sealing device that can be maintained at high speed.The structure of the present invention will be explained below based on illustrated embodiments.

In FIGS. 2 and 3, 18 is a casing provided on the upper part of the door valve 8 to accommodate and connect a shaft sealing device to be described later, and the outer cylinder 9 of the fuel exchange main body is enclosed within this casing 18. A shaft sealing device 19 is installed in a stored position.

Note that 20 is a support frame provided in place of the airtight container in FIG. 1, and a winding drum 14 of a hoist mechanism is supported at the top.

Further, the wire lobe 15 wound around the winding drum 14 is connected to the drive unit 12 via a detachable connector 21.

On the other hand, the detailed structure of the shaft seal device 19, as shown in FIG. It is equipped with a packing 23 made of multi-layered f'lEV type elastic rubber for sealing gas leakage and a braided body 24 of, for example, corrosion-resistant metal wire for wiping off sodium adhering to the surface of the outer cylinder 9 due to the adhesion of sodium vapor. It is composed of

The shaft seal housing 22 of the shaft seal device 19 has a flange, and the flange surface is hermetically sealed with the casing 18 via an O-ring 25, and a fixing bolt 26
This makes it possible to attach it to the casing 18.

On the other hand, the shaft seal housing 22 is connected to the drive section 12 of the fuel exchange body.
It can also be attached to and detached from the fixing bolt 27.

Among the fixing bolts 26 and 27, the fixing bolt 26 connects the shaft sealing device 19 to the casing 18 only during fuel exchange.

When replacing the fuel, remove the fixing bolt 27 and pull out the drive unit 12 provided at the top above to replace the fuel. When removing the fuel exchange rock 3 from the furnace, remove the fixing bolt 26 and tighten the fixing bolt 2γ to remove the shaft. The sealing device 19 is coupled to the drive section 12, and the shaft sealing device 19 and the drive section 12 are removed together.

In the above configuration, when exchanging fuel, the casing 18,
In other words, the outer cylinder 9 passes through the shaft sealing device 19 fixed on the furnace side.
slides up and down.

In this case, the gripper 1 is raised and lowered for fuel exchange.
The vertical stroke of 1 is slightly longer than the length of the fuel assembly, and in a normal nuclear reactor, the height h from the sodium liquid level to, for example, the door valve 8 in Fig. 2 is the vertical stroke of the gripper. It is configured to be sufficiently larger than the stroke.

Therefore, the portion of the outer cylinder immersed below the sodium liquid level does not rise to the position of the shaft sealing device 19 within the range of lifting and lowering operations during fuel exchange.

Therefore, the sealing mechanism of the shaft sealing device 19 does not directly wipe off the sodium adhering to the outer cylinder 9, but only wipes off a small amount of sodium vapor that has adhered.

On the other hand, when removing the fuel exchanger 3, first remove the main body from the second
As shown in the figure, the connector 21 is disconnected from the lowermost position, and the support frame 20 is first removed together with the hoist mechanism.

Next, the fixing bolt 26 is removed to disconnect the shaft seal device 19 and the casing 18, and the shaft seal device 19 is newly coupled to the drive section 12 of the fuel exchanger using the fixing bolt 27.

This work can be done directly by the worker.

In this state, a handling cask 28 as shown in FIG. 4 is set on the door valve 8.

The handling cask 28 is composed of a container 29 with a shielding function, a door valve 30 provided at the lower end, a hoist a structure 31 installed at the top, a grab 32 provided at the tip of a wire lobe, and the like.

Note that it is also possible to use the cask for handling other equipment without preparing a special cask.

Finally, grab the drive part 12 of the fuel exchanger main body with the grab 32, pull up the entire body into the cask capacity 29, and pull the door valve 8
330 is closed and the process ends.

In this way, the shaft sealing device 19 is housed in the handling cask 28 while being connected to the drive section 12 at the top of the main body.

Therefore, even in the process of pulling up the fuel exchanger from inside the furnace, the lower area of the outer cylinder 9, which had been immersed below the sodium liquid level in the furnace, does not pass through the sealing mechanism of the shaft sealing device 19, and a large amount of sodium chloride remains as in the case of refueling. is not directly wiped off by the sealing mechanism of the shaft sealing device 19, and a large amount of sodium can be prevented from accumulating in the shaft sealing device 19.

As described in detail above, according to the present invention, the fuel exchanger is equipped with a shaft sealing device that is fixed to the furnace side during fuel exchange and is fixed to the top of the fuel exchanger and removed as a unit when the fuel exchanger is removed. Therefore, even when the refueling rock is pulled out of the furnace to remove it, a large amount of sodium attached to the outer cylinder will not be deposited on the shaft sealing device, and early deterioration of the sealing mechanism will be prevented. This has the practical effect of maintaining a stable sealing function for a long period of time.

In addition, since the long and heavy airtight container conventionally employed can be omitted, it is extremely advantageous in terms of earthquake-resistant design, and a practical fuel exchange device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional fuel exchange device, Fig. 2 is an overall configuration diagram of an embodiment of the present invention, Fig. 3 is a detailed enlarged sectional view of the shaft seal penetration part in Fig. 2, and Fig. 4 is a fuel exchange device. FIG. 6 is a diagram showing a removed state in which the replacement rock main body is stored in the handling cask. 1: Rotating plug, 3: Fuel exchanger, 8: Inlet/outlet shielding valve, 9: Outer cylinder, 11: Gripper, 12: Drive section provided at the top, 13.14: Voist mechanism, 18: Shaft sealing device casing , 19: shaft sealing device, 22: shaft sealing housing,
23: Packing made of multiple layers of corrosion-resistant V-shaped elastic rubber, 24: Braided body of corrosion-resistant metal wire, 25: Seal member, 26, 27: Fixing bolt.

Claims (1)

[Claims] 1. An outer cylinder inserted into the hole by passing through a rotary plug in the upper part of the furnace and a shielding valve for the inlet/outlet hole of the rotary plug, a gripper attached to the lower end of the outer cylinder, and a gripper for operating the gripper. For the fuel exchanger, which is composed of a drive section provided at the top of the outer cylinder and is lifted and lowered by a hoist structure as necessary, there is a shaft seal housing surrounding the outer periphery of the upper end of the outer cylinder, and a shaft. It consists of a seal mechanism provided on the inner peripheral surface of the seal housing to form a primary cooling system boundary, and is fixed to the furnace side via an airtight coupling mechanism during fuel exchange, and is attached to the drive section of the fuel exchange machine when the fuel exchange machine is removed. A fuel exchange device for a nuclear reactor, comprising a shaft seal device that is fixed to the side and removed from the reactor side together with the fuel exchange device. 2. In the fuel exchange device according to claim 1, the mechanism for airtightly coupling the shaft seal housing of the shaft seal device to the furnace side is a casing that extends above the inlet/outlet shielding valve and surrounds the outer periphery of the shaft seal housing. and a fixing bolt that connects the facing flange surfaces of the casing and the shaft seal housing to the seal member and each flange.