JPS5826398Y2 - Receiver for collecting dripping sodium used in nuclear reactor fuel handling equipment - Google Patents

Description

[Detailed explanation of the invention] This invention was developed to collect sodium that drips from the fuel being handled when the spent fuel taken out from the reactor core is handled by the fuel handling machine in a liquid metal sodium cooled fast breeder reactor. This invention relates to a tray for collecting dripping sodium attached to the door pulp of a fuel handling machine.

In the fast breeder reactor mentioned above, spent fuel taken out from the reactor core is transferred to a spent fuel storage facility by operating a fuel handling machine.

As is well known, this fuel handling machine is equipped with a door pulp at the lower end of the fuel storage cylinder in order to isolate the fuel storage section from the outside atmosphere and maintain airtightness.

On the other hand, spent fuel is removed from the reactor core or fuel storage equipment by a fuel handling machine, either alone or in a transfer pot, but in either case, the liquid used as a coolant attached to the surface of the spent fuel is lifted up. Metallic sodium drips during fuel handling and solidifies and deposits on the door pulp, which may impede the opening/closing operation of the door pulp, or cause damage due to the induced radioactivity of the dripped sodium.

As a countermeasure against this problem, it is known that a saucer is placed on top of the door pulp to collect the dripping sodium, and the saucer catches the dripping sodium to prevent it from scattering in all directions.

By the way, the sodium collected by dripping into the saucer has inducible radioactivity and is inherently extremely chemically active, so careful handling or removal is required.

However, the conventional saucer for collecting dripping sodium has a simple bowl-shaped structure, and each time the sodium that has solidified and accumulated therein must be remelted and removed or washed, the saucer must be removed from the handling machine. It must be taken outside and turned over or turned over from its original position.

Moreover, handling of the saucer must be done remotely, which not only makes handling the radioactive sodium troublesome, but also requires special equipment for removing sodium from the saucer and cleaning it during the fuel handling process. There were also troublesome problems in terms of the equipment required.

The present invention was devised as a solution to the above-mentioned problems, and does not require a special remote-controlled removal device for the dripping sodium collection tray, making it possible to easily remove the collected sodium with simple handling operations. The purpose is to provide a saucer.

In order to achieve this object, the present invention is characterized in that a siphon-type sodium outflow path is provided in the dripping sodium collecting tray so that the remelted sodium flows out of the tray and is removed by the siphon action. do.

Below, the structure and sodium removal operation of the present invention will be described in detail based on illustrated embodiments.

Figure 1 shows the door valve installed at the lower end of the fuel handling machine', where 1 is the door valve casing, 2,
Reference numeral 3 indicates a through hole opening above and below to serve as a fuel passage; 4 indicates a valve box which is disposed within the casing and is operated to open and close in the direction of arrow A; and 5 is attached to the upper part of the valve box 4 and is the object of the present invention. This is a saucer for collecting dripping sodium.

The saucer 5 is removably placed on the valve box 4,
The handling operation is performed by attaching and detaching the valve body 4 to and from the valve box 4 using a fuel handling gripper in a fuel handling machine via a handling adapter (not shown).

By the way, according to the present invention, the dripping sodium collecting tray 5 has a siphon type sodium outflow channel 6 as shown in FIG.
is provided.

This outflow passage 6 is formed to penetrate the side wall of the saucer 5, and has a hairpin shape with one end opening near the bottom area inside the saucer and the other end opening near the bottom area outside the saucer, communicating the inside and outside. It will be used as a siphon passage.

Reference numeral 7 denotes a handling head formed on the upper edge of the saucer, 8 a gripping claw of a handling adapter engaged with the handling head 7, and 9 dripping from the fuel during fuel handling and collected on the saucer 5. This shows the deposited sodium that has solidified.

As is well known, liquid metal sodium, which is in a molten state at high temperatures, is transferred from the fuel transfer pot to the saucer 5 during handling.
When dropped, the temperature immediately drops and solidifies.

Therefore, the sodium 9 collected in the saucer 5 does not flow out through the siphon type sodium outflow path 6 at that time.

Next, the operation for removing sodium collected in the saucer 5 will be described.

When the saucer 5 is filled with the dripping sodium 9 while attached to the door pulp as described above, the saucer 5 is first filled by operating the handling adapter and the gripper of the fuel handling machine described above.
is removed from the valve box 4 and pulled upward, and then the fuel handling machine is opened to open the 11-door pulp connected to the furnace vessel or fuel storage tank, and the saucer 5 is melted in the furnace vessel or fuel storage tank as shown in Fig. 3. It is immersed in a hot sodium solution 10.

By maintaining this state for a while, the sodium 9 solidified and deposited in the saucer is heated and remelted by the surrounding high-temperature liquid metal sodium 10 in a molten state.

When the dripped sodium 9 collected in the saucer 5 is remelted,
Next, as shown in FIG. 4, the gripper is operated to lift the saucer 5 above the surrounding sodium liquid level.

Therefore, the sodium in the saucer flows out through the sodium outflow path 6 in the direction of arrow B due to the siphon action and is returned into the reactor vessel or fuel storage tank.

After draining the sodium, the saucer 5 can be reused by attaching it to the door pulp valve box 4 again as shown in FIG.

Other heating means can also be used to remelt the sodium.

As is clear from the above description, according to the configuration of the present invention, the dripped sodium collected by the IT in the same posture as when in use is discharged to the outside through the siphon-type sodium outflow path without overturning or reversing the saucer itself. It can be removed.

Therefore, without the need for a special remote control device for overturning and reversing the saucer as in the past, the sodium can be discharged and removed from the saucer with a simple operation using the existing fuel handling machine gripper.

Furthermore, the dripping sodium collected in the saucer is transferred to the reactor vessel,
Alternatively, it is possible to directly return the sodium to the fuel storage tank, so it is possible to provide a dripping sodium collection tray that is easy to handle and has the advantage of not requiring treatment as radioactive waste. can.

The saucer for collecting dripping sodium according to the present invention can be used not only by being attached to the door pulp of a fuel handling machine, but also as a saucer for dripping sodium to be used in various other equipment in fuel handling equipment.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the overall structure of a door pulp equipped with a dripping sodium collection tray, FIG. 2 is a longitudinal sectional view of the dripping sodium collection tray according to an embodiment of the present invention, and FIGS. 3 and 4 are FIG. 3 is an explanatory diagram of the operation for removing sodium. 5... Receiver for collecting dripping sodium, 6...
...Siphon type sodium outflow channel, 9...Sodium collected and solidified in the saucer, B...
...Direction of flow of remelted sodium.

Claims (1)

[Scope of utility model registration request] In a dripping sodium collection tray that is installed in a reactor fuel handling machine and collects sodium dripping from the fuel being handled or from a fuel transfer pot, one end is opened near the bottom area of the tray, and the other end is a saucer. A saucer for collecting dripping sodium used in a fuel handling machine for a nuclear reactor, characterized by having a siphon-type sodium outflow path that opens near the outer bottom area and communicates between the inside and outside of the saucer by bending it.