JPH0153757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hot cell type fuel loading/unloading facility for delivering and transferring fuel between a nuclear reactor vessel and a hot cell.

Figure 1 shows the fuel inlet/outlet equipment that transfers spent fuel extracted from the reactor core to the ex-core fuel storage tank, or conversely, transfers new fuel carried into the ex-core fuel storage tank to the reactor vessel. A hot cell system as shown is known. That is, a hot cell 4 for fuel transfer is installed between the reactor vessel 1 and the external fuel storage tank 2, spanning the inside and outside of the reactor containment vessel 3. This hot cell 4 is isolated from the outside and its interior is maintained in an inert gas atmosphere, and a fuel transfer carriage 6 that runs on rails 5 is further provided within the hot cell. Also, between the hot cell 4 and the furnace vessel 1, and between the hot cell 4 and the furnace vessel 1,
and the out-of-core fuel storage tank 2 are connected by inclined chutes 7 and 8, respectively. Shoot 7 of these
To explain in more detail, Figures 2 and 3
As shown in the figure, the chute 7 passes through the upper shield plug 9 of the reactor vessel 1 and is piped between the in-furnace fuel support rack and the hot cell 4, and the guide rail 11 of the fuel bucket 10 is laid in the chute 7. It has been done.
Furthermore, at the upper open end of the chute 7 that opens into the hot cell, there is a port cover 12 that closes the chute 7 during furnace operation and forms a boundary for cover gas in the furnace.
is provided. In the figure, 13 is a hoist with a power manipulator installed in the hot cell;
4 is a manipulator for repairing equipment inside the cell which is operated from outside the hot cell; 15 is a pit; 16 is a thin body that surrounds the exposed part of the chute 7;
7 is sodium as a primary cooling member housed in the furnace vessel, and 18 is a furnace cover gas. With the above configuration, the spent fuel is once stored in the fuel bucket 10 and lifted to the carriage 6 through the chute 7, and from there, it is transferred together with the carriage 6 to the opposite end of the hot cell 4, and then sent to the outside fuel storage via the chute 8. It is suspended into tank 2. Moreover, the new fuel is carried into the reactor in the reverse order to the above.

On the other hand, in the above fuel inlet/output equipment, when the fuel exchange is completed, a plug 19 shown by a broken line is suspended from the open end on the hot cell side into the chute 7 and inserted and loaded, and the port cover 12 is closed.

Here, the conventional plug 19 was made to have the following functions. In other words, the above function is a radiation shielding function that suppresses radiation such as neutrons that leaks from the reactor vessel side into the hot cell through the chute 7 during reactor operation in order to prevent activation of various equipment in the hot cell. , a heat shielding function that suppresses radiant heat from the sodium liquid level in the furnace and heat transfer due to convection of the cover gas, and prevents sodium vapor from entering the upper part of the chute and being deposited as the convection of the cover gas increases. This is a protective function that prevents damage. By the way, as mentioned above, the fuel bucket guide rail 11 is originally installed inside the chute 7, and this rail gets in the way, making it impossible to completely block the chute 7 with the plug 19, which prevents radiation streaming. It is inevitable that some leakage gaps will remain. For this reason, conventionally, in consideration of streaming, the flexible thickness of the plug 19 is set in advance to be much thicker than the required dimension necessary for blocking radiation transmission. For this reason, the plug 19 is large in size and extremely heavy. As a result, the plug 19 is
When inserting the plug into the inclined chute, it is not possible to insert the plug into the inclined chute by simply suspending the plug using the hoist 13 and using remote control.
A swing mechanism for tilting the plug 19 is required separately from the hoist 13, and handling the plug 19 requires large-scale dedicated handling equipment and troublesome work.

This invention has been made in consideration of the above points, and its purpose is to solve the difficulties in conventional equipment, improve the radiation shielding function for the hot cell, and provide a heat shielding function for the shute plug and a shut-off function from the reactor vessel side. To provide an improved fuel inlet/outlet equipment that has a packing function to prevent the cover gas from rising and entering the furnace inward, and which simplifies the equipment and work required for handling the chute plug compared to the conventional one. be.

The present invention will be described in detail below based on illustrated embodiments.

FIG. 4 shows the configuration of an embodiment showing the state during furnace operation. According to the present invention, first, the open end of the chute 7 toward the hot cell side is provided with a fuel passageway surrounding the fuel passage in the chute. A radiation shielding body 20 is newly installed around the chute 7, and a radiation shielding body 21 is newly installed on the inner surface of the port cover 12, which closes during furnace operation and forms a boundary for the cover gas in the furnace. The shielding bodies 20 and 21 share the radiation shielding function, which was conventionally performed by the plug 19 shown in FIG. On the other hand, the chute plug 22 inserted and loaded into the chute 7 during furnace operation does not particularly require a radiation shielding function, and is configured as a small and lightweight plug equipped with the heat shielding function and packing function described above. . Its structure is as shown in the figure.
The plug body is provided with a guide roller 23 that fits into the plug body, and a labyrinth packing portion 24 in the form of a large number of ribs on the outer peripheral area of the plug body. The insertion and removal of the chute plug 22 is carried out by gripping the handling part formed on the top of the plug body with a gripper attached to the hoist shown in FIG. be exposed. Note that the reference numeral 25 in FIG. 4 is a cooling and heating jacket installed around the chute 7. For example, when taking out spent fuel from the furnace, the jacket 25 is
Cooling gas is passed through the chute to remove decay heat from the fuel passing through the chute, and conversely, when new fuel is brought in, heating gas is sent in to preheat the fuel. Furthermore, by the heating described above, it is also possible to prevent the sodium vapor that has entered the chute 7 from solidifying and depositing on the inner surface of the chute. Further, the reference numeral 26 indicated by a chain line in FIG. 4 is an additional shield, which is normally stored at a predetermined location within the hot cell, and is only used when maintenance personnel enter the hot cell as necessary. It is used to enhance the radiation shielding ability by installing it in a certain position. The above structure can also be applied to the chute 8 connecting the hot cell 4 and the extra-core fuel storage tank 2 in FIG. 1.

As mentioned above, the present invention separates the radiation shielding function from the plug in conventional equipment, and distributes this function to the radiation shielding body equipped around the open end of the chute on the hot cell side and on the port cover. Therefore, compared to conventional plug-in shielding methods, streaming is completely eliminated and effective radiation shielding can be obtained.
Moreover, this flexible state is obtained by closing the port cover, and its handling can be easily performed without adding any new handling mechanism. In addition, by assigning the radiation resistance function to the chute side, the shute plug inserted into the chute during operation only needs to have a slight heat resistance function and a packing function. It becomes possible to use a small plug whose size and weight are significantly reduced compared to a plug, and the equipment necessary for handling the plug can be simplified and the work thereof can be made easier. Furthermore, by forming a labyrinth packing part on the chute plug as shown in the example, leakage of the cover gas from inside the furnace to the upper part of the chute through the circumferential gap between the plug and the inside surface of the chute is effectively suppressed, and the sodium This invention can bring about a number of practical effects, such as preventing steam from entering.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire fuel inlet/output equipment of a nuclear reactor, which is the subject of this invention, Fig. 2 is a detailed enlarged view of the reactor side part in Fig. 1, and Fig. 3 is a fuel bucket of the chute in Fig. 2. FIG. 4 is an enlarged cross-sectional view showing the passing state, and FIG. 4 is a structural cross-sectional view of an embodiment of the present invention. 1... Reactor vessel, 4... Hot cell, 6...
Fuel transfer carriage, 7, 8... Slope type chute, 9... Reactor vessel shield plug, 10... Fuel bucket, 11... Guide rail, 12... Port cover, 20, 21... Radiation shield. Yahei body, 22...
...Shute plug, 24...Labyrinth packing part.

Claims (1)

[Claims] 1 The reactor vessels are lined up, and a hot cell is installed inside the reactor vessel that spans the inside and outside of the reactor containment vessel, and a fuel transfer carriage runs inside the hot cell. In a fuel inlet/output facility for a nuclear reactor, in which the fuel buckets are connected by a ramp type chute with a guide rail, and the fuel is taken in and out and transferred through the chute by operating the fuel transfer carriage, the area around the open end of the chute on the hot cell side and The port lid, which closes this open end and forms a boundary for the cover gas in the furnace during furnace operation, is equipped with a radiation shielding body. A shute plug having a labyrinth packing part is provided, and the shunt plug is provided with the function of shielding against radiation leaking from the reactor vessel side into the hot cell, and the shute plug is provided with heat shielding and radiation directed from the reactor vessel side into the chute. 1. A nuclear reactor fuel inlet/output facility characterized by having a packing function to prevent cover gas from rising and entering the reactor.