JPH0477876B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a nuclear fuel oxidation and recovery apparatus that heats sintered scrap generated in a nuclear fuel pellet manufacturing process in an air atmosphere, converts it into oxidized powder, and recovers the sintered scrap.

[Technical background of the invention and its problems]

Generally, in order to oxidize and pulverize sintered scrap generated in the nuclear fuel pellet manufacturing process and recover it, the nuclear fuel sintered body is fed to a sieve installed in an oxidation furnace, and the sintered body is placed in an air atmosphere. By applying vibration while heating the sintered body, the sintered body is turned into a powdered oxide, which is then dropped into a collection container and collected.

However, in such equipment, since the inside of the oxidation furnace is under positive pressure, there is a possibility that fine particles of nuclear fuel material may leak from the equipment, and the sieve inside the furnace may be damaged due to thermal expansion of the oxidation furnace. There are inconveniences such as the level with the vibrator being shifted, or the furnace being tilted and the sieve coming into contact with the inside of the furnace, making it impossible to vibrate the sieve smoothly.

[Purpose of the invention]

In view of these points, it is an object of the present invention to provide a nuclear fuel oxidation and recovery device that can reliably prevent the fuel material from leaking from the oxidation furnace and prevent the adverse effects on the sieve due to thermal expansion of the oxidation furnace. With the goal.

[Summary of the invention]

The present invention provides a nuclear fuel oxidation and recovery apparatus that heats sintered scrap generated in the nuclear fuel pellet manufacturing process in an air atmosphere, oxidizes it into powder, and recovers it, and maintains a negative pressure in the oxidation furnace to which the sintered scrap is supplied. In addition to supplying oxidizing gas such as air, the sieve installed in the oxidizing furnace is connected to a vibrator via a connecting rod, and the connecting rod is covered and the oxidizing furnace is operated. It is characterized in that the cladding tube fixed in the furnace is connected to the vibrator via an expansion/contraction joint.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes an oxidation furnace storage container that houses an oxidation furnace 2 inside and is constructed of a heat insulating wall 3. It is supported by a support 6. The oxidation furnace 2 has a cylindrical body part 2a, and a funnel-shaped part 2b is formed in the lower part of the body part 2a. A collection pipe 7 extending upward through the wall
The recovery pipe 7 is opened to a recovery container 9 via a water-cooled valve 8. Furthermore, air supply pipes 10a and 10b are connected to the upper side walls of the funnel part 2b and the body part 2a of the oxidation furnace 2, respectively, and the oxidation furnace 2
Inside, a sieve 11 is concentrically arranged, in which a plurality of sieve plates 11a, 11b, and 11c are arranged in upper and lower stages in a plurality of sieve plates 11a, 11b, and 11c, the number of meshes of which increases toward the bottom.

The sieve 11 is connected to a vibrator 12 supported by the pillar 5 via a connecting rod 13, and a cladding tube 14 that covers the connecting rod 13 and is fixed to the top wall of the oxidation furnace 2 A bellows 15 is interposed between the vibrator 12 and the vibrator 12 . Further, above the sieve 11, the lower ends of a sintered body supply pipe 16 and an exhaust pipe 17, which are respectively fixed to the oxidation furnace 2, are opened. They extend upward through the top wall of the oxidation furnace storage container 1 and are connected to the feeder 18 and the exhaust blower 19, and furthermore, a water cooling valve 20 and a bellows 21 are interposed in the middle of the sintered body supply pipe 16, A bellows 22 is interposed in the middle of the exhaust pipe 17. On the other hand, the feeder 18 is provided with an optical sensor 23 for detecting the amount of the sintered body (sintered scrap) being delivered, and a heater 24 is further provided in the oxidation furnace storage container 1.

The sintered body fed to the feeder 18 is detected by an optical sensor 23 and fed by a timer (not shown), and the feeding operation is controlled at regular intervals. Supplied on top. On the other hand, the inside of the oxidation furnace 2 is maintained at a predetermined temperature by the heater 24, and
Air is supplied by air supply pipes 10a and 10b. Therefore, the sintered body supplied to the sieve 11 passes through the uppermost sieve plate 11a in an air atmosphere.
A vertical vibration is applied by the sieve 11 which is heated above and vibrated by a vibrator 12 via a connecting rod 13. Therefore, the surface of the sintered body is oxidized, and the oxide peels off from the surface layer of the sintered body.
The particles pass through the mesh of the sieve plate 11a, are further oxidized on the next sieve plate 11b immediately below, become fine particles, pass through the sieve plate 11b, and finally the lowest sieve plate 11c.
The particles become fine particles and are collected into a collection container 9 via a collection pipe 7.

On the other hand, as mentioned above, a constant flow of air is sucked into the oxidation furnace 2 by the exhaust blower through the air supply pipes 10a and 10b, and this suction also creates a negative pressure inside the furnace. This prevents nuclear fuel material from leaking out of the reactor.

In addition, as the sintered body is dropped as described above, the air supplied into the oxidation furnace 2 is sucked upward and flows in opposite directions, so that the oxidation of the sintered body is promoted and the oxygen in the air is effectively used for oxidation, and since the sintered body is supplied at regular intervals, the temperature inside the oxidation furnace is not fluctuated by the supply of the sintered body, and the temperature is always maintained almost constant. The oxidation reaction is extremely stable, and a high-quality and uniform oxide is obtained.

Furthermore, although the oxidation furnace 2 expands during the above operation, the cladding tube 14 that supports the upper part of the oxidation furnace 2 expands.
Since an expansion/contraction joint such as a bellows 15 is interposed in the middle of the oxidation furnace 2, the expansion of the oxidizing furnace 2 is absorbed by this expansion/contraction joint, regardless of the connection between the vibrator 12 and the sieve 11, and the sieve 11 is tilted. This prevents the smooth vibration of the sieve from being disturbed due to the level difference between the sieve and the vibrator.

〔Effect of the invention〕

As explained above, in the present invention, the oxidation furnace to which sintered scrap is fed is operated under negative pressure, and the sieve provided in the oxidation furnace is connected to the vibrator. The cladding tube that covers the rod and is fixed in the oxidation furnace is connected to the vibrator through an expansion/contraction joint such as a bellows, so there is no risk of leakage of nuclear fuel material, and the thermal expansion of the oxidation furnace is absorbed and the vibration is reduced. The function of the machine is not impaired, and high-quality and uniform oxide can always be obtained.

[Brief explanation of the drawing]

The figure is a longitudinal sectional side view showing a schematic configuration of the nuclear fuel oxidation recovery device of the present invention. 2... Oxidation furnace, 7... Recovery pipe, 9... Recovery container, 10
a, 10b...air supply pipe, 11...sieve, 12...
Vibrator, 15... bellows, 16... sintered body supply pipe,
17...exhaust pipe, 18...feeder, 19...exhaust blower, 21, 22...bellows.

Claims (1)

[Scope of Claims] 1. In a nuclear fuel recovery device that heats sintered scrap generated in the nuclear fuel pellet manufacturing process in an air atmosphere, converts it into oxidized powder, and recovers the sintered scrap, the sintered scrap is supplied to an oxidation furnace. An exhaust pipe connected to an exhaust blower is connected and an air supply port is opened to operate the furnace in a negative pressure state, and a sieve installed in the oxidation furnace and to which the sintered scrap is supplied is connected. A nuclear fuel oxidation and recovery device, characterized in that the cladding tube is connected to a vibrator via an expansion/contraction joint, and a cladding tube that covers the connecting rod and is fixedly installed in the oxidation furnace is connected to the vibrator via an expansion/contraction joint. 2. The nuclear fuel oxidation and recovery apparatus according to claim 1, wherein the sintered scrap is supplied to the oxidation furnace intermittently and at a constant rate. 3. The nuclear fuel oxidation and recovery apparatus according to claim 1, wherein the sintered scrap in the oxidation furnace is made to flow in opposite directions with an oxidizing gas such as air.