JPS6220520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-core relay device that relays fuel between a fuel exchange machine and a fuel inlet/output machine in a nuclear reactor during fuel exchange in a liquid metal cooled fast breeder reactor.

In general, fuel exchange in the above mentioned nuclear reactor involves a fuel loading/unloading machine that carries new fuel into the reactor from outside the reactor and removes spent fuel, and a fuel exchange machine that loads and withdraws fuel from the core inside the reactor. The fuel is transferred between the fuel exchange machine and the fuel inlet/output machine within the reactor via an in-furnace relay device.

Here, the conventional configuration of such an in-furnace relay device will be explained with reference to FIG. In the figure, 1 is the upper part of the reactor plug filled with liquid metal sodium Na as the primary coolant, and 2 is the reactor inserted into the operating position in the reactor through the through hole of the part 1. The internal relay device 3 is a transfer pot that accommodates the fuel being relayed within the reactor. The in-core relay device 2 includes a large-diameter storage cylinder 20, a guide cylinder 21 housed and supported within the storage cylinder 20, and a rotating rack drive shaft disposed along the guide cylinder 21 and on the side thereof. 22, a rotating rack 23 attached to the tip of the drive shaft 22, and a drive device 26 consisting of a transmission gear mechanism 24 and a drive motor 25, which are interlocked and connected to the upper end of the drive shaft 22 outside the furnace.
The guide cylinder 21 forms a fuel inlet/outlet passage that spans the inside and outside of the reactor, and is equipped with a handling head 27 at its upper end for gripping with a dedicated handling machine when pulling the entire in-furnace relay device out of the reactor. . Further, the drive shaft 22 and the drive device 26 are pivotally supported via a bearing 28 installed in the housing outer cylinder. Rotating rack 2
3 is set so that its across dimension is slightly smaller than the diameter of the storage outer cylinder 20, and the drive shaft 2
It has a rack hole for supporting the fuel transfer pot 3 at a position just below the guide tube 21 when rotated about the fuel transfer pot 2. Note that 4 is the casing of the drive device installed on the shield plug 1,
A door valve (not shown) is installed above this.

The in-furnace relay device 2 is pulled into the furnace through the through hole of the damp plug 1 with the rotary rack 23 positioned directly below the outer housing cylinder 20, and then fuel is inserted above the guide cylinder 21 through a door valve. The ingress/egress machine is connected. In this state, the drive device 26 rotates the rotary rack 23 as shown by arrow A between the fuel transfer position I with the fuel inlet/output machine and the fuel transfer position with the in-core fuel exchanger, thereby transferring new fuel or Spent fuel is relayed within the reactor between the fuel exchange machine and the fuel inlet/output machine. Once the fuel has been replaced using the above method, the entire system is lifted out of the reactor using a dedicated handling machine, and instead, the through hole of the shield plug 1 is sealed with another plug, and the reactor is put into operation.

By the way, in the conventional in-furnace relay device having the above configuration, if a stuck accident occurs in the drive system of the rotary rack during operation and the rotating operation of the rotary rack 23 becomes impossible, the rotary rack at that time is Depending on the operating position of the rotary rack 23, there is a possibility that the rotating rack 23 may remain protruding laterally from the housing cylinder 20 and may not be able to be pulled out of the furnace through the through hole of the shrink plug 1. In particular, among the bearings 28 that pivotally support the drive shaft 22, the bearings located on the inside of the furnace are immersed in high-temperature sodium under harsh conditions, so they are susceptible to stagnant accidents, and even in transmission gear mechanisms. Static accidents often occur. Once such an accident occurs, the rotating rack becomes an obstacle and the in-core relay device cannot be easily taken out of the reactor, resulting in a serious hindrance to the reactor operating schedule.

The present invention solves the above-mentioned problems, and even in the event of an emergency in which a stuck accident occurs in the drive system of the rotary rack, the rotary rack can be moved from a route other than the drive device to a position directly below the storage cylinder, and the entire equipment can be moved to the furnace. The purpose is to provide a more reliable in-furnace relay device that can be taken out.

According to the present invention, the rotary rack drive shaft in the in-furnace relay device is connected directly to the drive device, and the hollow drive shaft is rotatably passed through the shaft up and down, and the joint is separable by external operation. It is constructed as a double shaft consisting of an emergency shaft that is connected to a hollow drive shaft through a shaft and an emergency shaft that can be operated independently from outside the furnace with the joint separated, and a rotary rack is attached to the tip of the emergency shaft. This is achieved by configuring the system so that when an accident occurs, the emergency shaft can be operated independently from outside the reactor with the joint disconnected, and the rotary rack can be moved to the take-out position directly below the storage cylinder.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention will be explained in detail based on the illustrated Example.

In FIG. 2, the basic structure of the in-core relay device is the same as that in FIG. 1. However, according to the present invention, the rotary rack drive shaft 22 has a hollow drive shaft 221 which is directly connected to the transmission gear mechanism 24 at the upper end and is pivotally supported by a bearing 28, and which passes through the hollow drive shaft 221 vertically. The hollow drive shaft 221 is inserted into the hollow drive shaft 221 via a key 29 that is rotatably inserted into the shaft and attached to the tip of the shaft.
It is configured as a double structure shaft with an emergency shaft 222 coupled to the emergency shaft 222. Further, the emergency shaft 222 is supported by a thrust bearing at its upper end, and a rotating rack 23 is attached to its tip after passing through the lower end of the hollow drive shaft 221. With this configuration, the power of the drive motor 25 is transmitted to the driven emergency shaft via the gear mechanism 24, the hollow drive shaft 221, and the key 29, and the rotary rack 23 is moved between it and the relay position I. Here, the key 29 attached to the emergency shaft 222 is a joint that is relatively loosely fitted into an axial key groove formed on the inner surface of the open end of the hollow drive shaft 221 and connects the shafts to each other in the rotational direction. The emergency shaft 222 is moved to the arrow B in FIG.
When the key 29 is moved slightly downward as shown in the figure, the key 29 comes out of the key groove of the hollow drive shaft 221, and the shafts are disconnected from each other. In that disconnected state, the emergency shaft 2
22 coupled to its upper end, for example, the operating handle 5.
It can be independently rotated together with the rotation rack 23 as shown by arrow C by turning the . In addition, as a joint that can disconnect the hollow drive shaft 221 and the emergency shaft 222 by external operation, various joint mechanisms such as a spline shaft or other clutch mechanism may be used instead of the key 29 shown in the illustrated example. can.

Next, we will discuss how to deal with an emergency when a stuck accident occurs in the drive system while the in-core relay system is operating. For example, if a stuck accident occurs in the bearing 28 of the drive shaft 22 immersed in sodium Na in the furnace or in the transmission gear mechanism 24, and it becomes impossible to rotate the hollow drive shaft 221, first The emergency shaft 222 penetrating the hollow drive shaft 221 on the outside of the furnace and projecting upward is lowered by external operation to the position shown in FIG. 3 where the key 29 is unlocked. Subsequently, the emergency shaft 222 is rotated independently by applying an operating force to its upper end, and the rotating rack 23 is returned to a position directly below the storage cylinder 20. By this operation, the in-furnace relay device 2 can be immediately pulled out of the furnace through the through hole of the shield plug 1, and the stuck portion can be repaired by being pulled out of the furnace.

As described above, according to the configuration of the present invention, even if a stay accident occurs on the hollow drive shaft side that is directly connected to the drive system among the double-structure rotating rack drive shafts, this stay will not affect the drive shaft at all. It is possible to rotate the rotary rack to any desired position by separating the emergency shaft from the hollow drive shaft and rotating it independently. As a result, even in the unlikely event that a static accident occurs, the in-reactor relay device can be immediately taken out of the reactor after the rotary rack is returned to its removal position, and the abnormality can be repaired, minimizing the impact on the reactor operating schedule. It has an excellent effect on improving reliability, such as by being able to suppress

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of the in-furnace relay device according to the conventional method and the embodiment of the present invention, respectively, and FIG.
FIG. 6 is an explanatory diagram of the operation of the drive shaft when a stake accident occurs in the figure. 1...Shiyahei plug, 2...Furnace relay device,
20... Storage outer cylinder, 21... Guide cylinder, 22... Rotating rack drive shaft, 221... Hollow drive shaft, 222
... Emergency shaft, 23 ... Rotating rack, 26 ... Drive device, 29 ... Key as a joint, 3 ... Fuel transfer pot.

Claims (1)

[Scope of Claims] 1. A guide tube for a fuel inlet/outlet passage extending between the inside and outside of the reactor;
A rotary rack drive shaft disposed along and to the side of the guide cylinder and a rotary rack attached to the tip of the drive shaft are pulled into the reactor together with the storage outer cylinder through the through hole of the shield plug in the upper part of the reactor; In an in-core relay system for reactor fuel, which relays fuel within the reactor by operating a rotating rack inside the reactor via a rotating rack drive shaft by a drive device outside the reactor, a hollow space in which the rotating rack drive shaft is directly connected to the drive device is used. The hollow drive shaft is connected to the hollow drive shaft through a joint that rotatably passes through the hollow drive shaft vertically and can be separated by external operation, and can be independently operated from outside the furnace with the joint separated. 1. An in-core relay device for reactor fuel, characterized in that it is configured as a double shaft consisting of an emergency shaft, and a rotating rack is attached to the tip of the emergency shaft. 2. In the in-furnace relay device according to claim 1, the joint that connects the hollow drive shaft and the emergency shaft connects the hollow drive shaft by moving the emergency shaft in the axial direction by external operation. An in-core relay device for nuclear reactor fuel, characterized in that the key is a key that connects and disconnects connections in the rotational direction between the two.