JPH0110637Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fuel exchange passage structure in a fast breeder reactor.

As one of the fuel exchange devices of the fast breeder reactor, a fuel transfer chamber is provided close to the reactor vessel and the ex-core fuel storage tank, and a slope extending to the reactor vessel and the ex-core fuel storage tank is connected to the fuel transfer chamber. A chute-type device has been proposed in which a fuel bucket containing spent fuel or new fuel is opened and relayed in a fuel transfer chamber, and fuel is transferred in and out of the reactor vessel via an inclined path.

The general configuration of the slope installed in this device is that a rectangular chute for guiding the fuel bucket is installed in a diagonal hole that penetrates the reactor vessel or the extra-core fuel storage tank. During reactor operation, the opening of this slope to the fuel transfer chamber is closed.

By the way, during reactor operation, the temperature at the bottom of the slope near the core of the slope installed inside the reactor vessel reaches approximately 500℃, and this temperature increases when the reactor is shut down and fuel is replaced. The temperature drops to 200℃ or below.

Furthermore, in the out-of-core fuel storage tank, a certain degree of temperature change is unavoidable depending on the amount of spent fuel in the tank.

Due to this temperature change, the rectangular cylindrical chute that makes up the slope expands and contracts due to heat, and consideration must be given to absorbing this.

Conventionally, for this purpose, a joint 20 has been used in which the chute is divided at the lower part of the chute 15 and a gap 19 is formed so that the chute can be expanded and contracted in the axial direction, as shown in FIG.

However, this method can only absorb displacement in the axial direction, and the stress generated by displacement in the direction perpendicular to the axis necessitates increasing the slope strength.

Further, in the case where a relative displacement occurs between the reactor vessel and the slope due to an earthquake, there is a risk that excessive force will be applied to the reactor vessel with the above-mentioned conventional joint configuration.

This idea was developed in view of the above points, and it is possible to skillfully absorb not only the axial displacement of the chute that constitutes the slope of the fuel exchange device, but also the displacement in the direction perpendicular to the axis, and to ensure the safety of the reactor vessel. The present invention aims to provide a slope configuration with improved performance.

Hereinafter, embodiments of this invention will be described with reference to the drawings.

Figure 1 schematically shows the overall configuration of a nuclear reactor to which this invention is applied, in which 1 is a reactor vessel, 2 is a reactor core, 3 is an extra-core fuel storage tank provided adjacent to the reactor vessel 1, and 4 is a nuclear reactor. 1 shows a fuel transfer chamber that connects the reactor vessel 1 and the fuel storage tank 3 and has an airtight and shielding function.

Reference numerals 5 and 6 denote slopes which are opened at the upper ends of the fuel transfer chamber 4 and are provided oppositely between the core 2 and the external fuel storage tank 3, and 7 is an opening of either of the two slopes 5 and 6. The movable truck 8 is a fuel bucket, which is connected to a cable 11 extending from a winding drum 10 mounted on a support frame 9 to move in and out of the movable track 7. The fuel is transported by going up and down inside the tank.

In the figure, reference numeral 12 indicates an in-core fuel exchange device installed on the reactor vessel 1, and 13 indicates an ex-core fuel exchange device installed on the extra-core fuel storage tank 3.

Now, in this invention, the slopes 5 and 6 are formed by a diagonal hole 14 provided through the reactor vessel 1 and the external fuel storage tank 3, and a rectangular cylindrical chute 15 disposed within the diagonal hole 14. This shoot 1
The chute 15 is divided into parts at the lower part of the chute 5, and a plurality of short tube bodies 16 are arranged in series, and these short tube bodies 16 and the lower end of the chute and the short tube body 16 are connected to opposite two-sided edges. A flexible part 18 formed by connecting the pin 7 in a freely bendable manner is inserted, and the flexible part 18
Subsequently, a joint 20 with a slight gap 19 is formed.

Incidentally, a gap 21 is formed from above between each of the short tube bodies 16 in the flexible part 18 to allow free bending, but this allows the wheels of the fuel bucket 8 to easily overcome this gap. Set to range.

In the above configuration, according to this invention, thermal displacement of the chute 15, which is a slope component, caused by temperature changes due to reactor operation and shutdown can be caused not only in the axial direction but also in the direction perpendicular to the axis. This is absorbed by the flexible portion 18.

Therefore, unnecessary force is not applied to the chute-related parts, which is advantageous from the viewpoint of slope strength design, and even if excessive force is applied to the reactor in the event of an earthquake, this will not be applied to the outside via the slope. It is also effective in terms of earthquake countermeasures, as it can prevent the damage from spreading to others as much as possible.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a fuel exchange device to which the slope of this invention is applied, Fig. 2 is a side view of the main parts, Fig. 3 is a plan view, and Fig. 4 is a cross section taken along line a-a in Fig. 3. FIG. 5 is a partial side view of a conventional example. 1...Reactor vessel, 2...Reactor core, 3...External fuel storage tank, 4...Fuel transfer chamber, 5, 6...Slope,
7...Movable truck, 8...Fuel bucket, 9...
... Support frame, 10 ... Winding drum, 11 ... Cable, 12, 13 ... Fuel exchange device, 14 ... Diagonal hole, 15 ... Chute, 16 ... Short tube body, 17 ...
... Pin, 18 ... Flexible part, 19 ... Gap, 20
...Joint, 21...Gap.

Claims (1)

[Scope of utility model registration request] A fuel exchange system in which a fuel transfer chamber is provided close to the reactor vessel and the external fuel storage tank, a fuel bucket is relayed in the fuel transfer chamber, and fuel is transferred in and out of the reactor vessel via a slope using a chute method. In the device, a diagonal hole is provided through the reactor vessel or the storage tank to provide a diagonal path connecting the inside of the reactor vessel and the fuel transfer chamber, and a diagonal path connecting the external fuel storage tank and the fuel transfer chamber, and the diagonal hole. It consists of a rectangular tubular chute that guides the fuel bucket placed inside the chute, and a plurality of short tube bodies are arranged in series at the lower end of the chute, and the short tube bodies and the lower end of the chute and the short tube bodies are arranged opposite to each other. A fuel exchange passage structure in a fast breeder reactor, characterized in that a flexible part is inserted which is formed by bendably pin-coupled at the edges of two sides.