JPS5916558A - Centrifugal separator for reprocessing of nuclear fuel - Google Patents

Abstract

PURPOSE:To improve resistance to earthquake and to revolve stably a driving shaft without spoiling aligning property by using a porous metal for the material of a spherical seat which supports oscillatably a bearing cylinder and impregnating oil therein. CONSTITUTION:A flange 10b in the upper part of a spherical seat 10 is connected to a flange 12b in the upper part of a bearing cylinder 12 by way of a damper 13 so that the oscillating energy of a driving shaft 9 can be absorbed against oscillation such as an earthquake. If a porous metal such as, for example, a sintered metal is used for the material of a spherical seat 20, and if oil is impregnated thereon, an oil film is always formed in the engaging and sliding contact part between the hollow spherical face 10a of the seat 10 and the projecting spherical face 12a of the cylinder 12. As a result, a shearing type damper determined by the viscosity of the oil, the thickness of the oil film, and the area of the engaging and sliding contact part is formed, and the resistance to earthquake is improved and the stable revolution of the driving shaft is maintained without spoiling the aligning property which is the initial purpose of the spherical seat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a centrifugal separator for nuclear fuel reprocessing, in which a rotating bowl and a driving section thereof are separated by a slab.

[Technical Background of the Invention] Centrifugal separators for nuclear fuel reprocessing include centrifugal clarifiers that separate and remove solid particles such as insoluble fission products from a nitric acid solution of spent nuclear fuel, and uranium clarifiers that separate and remove solid particles such as insoluble fission products from a nitric acid solution of spent nuclear fuel. There are also centrifugal extractors that perform liquid extraction to separate plutonium and fission products.

Since the centrifugal separator described above handles extremely highly radioactive materials, the rotating bowl part that comes into contact with the processing liquid and the driving part that includes the motor, bearings, etc. that drive it are radioactive materials made of concrete, lead, etc. Isolated by shielding slabs.

That is, as illustrated for the centrifugal extractor in FIG. It is isolated by a shielding slab 1.

The housing 4 of the drive unit 2 has an inner flange 5a, and is formed by a lower member 5 whose lower surface is fixed to the upper surface of the slab 1, and an upper member 7 which is fixed to the upper surface and has a motor 6 on the upper surface. ing.

The drive shaft 9 that extends from the motor 6 through the slab 1 and projects downward from the slab and suspends and supports the rotary bowl 8 is supported so as to be swingable and rotatable in the following manner. That is, an upwardly opening spherical seat 10 is attached to the upper surface of the inner flange 5a, and the bearing sleeve 12 that supports the ball bearing 11 engaged with the drive shaft 1119 is connected to the concave spherical surface 108 of the spherical seat 10.
It has a convex spherical surface 12a that engages and slides into contact with and 12a.

fxo, upper flange job of spherical seat 10 and bearing tube 1
2 and the upper 7 land 12b are connected via a Danno: -13. Further, at the lower end of the bearing tube 12, a spring 14 is attached to the lower tube 10C of the spherical seat 10 in a movable sliding manner.
Support member 1 to which a spring force is applied toward the center of the bearing cylinder
5 is engaged. In addition, 152 in the figure is the support member 15.
A spring holder at the outer end is shown, and the spring 14 is a tension spring with one end fixed to the spring holder 15.

The wetted part 3 has a rotating bowl 8 that rotates within a fixed container 16 fixed to the slab 1. Separation in the liquid contact part 3 is performed by introducing the aqueous solution into the fixed container 16 from an external solution port 17 provided in the fixed container 16, and further introducing it into the rotating rotary bowl 8, and mixing chambers formed in multiple stages within the rotating bowl 8. This is carried out by introducing the fission products into a phase separation chamber and centrifuging them into the fission products and the aqueous solution.

[Problems in the background art] In the conventional centrifugal separator described above, the bearing tube 12 is mounted on a spherical seat J.
The reason why the shaft is supported by an O to enable oscillation is to provide alignment and to take into consideration the natural frequency of the drive shaft 9 system. As described above, the constants of the damper 13 and the spring 14 are arbitrarily set to pass through the resonance point of the so-called rigid body mode. At this resonance point, when the rotation speed is lowered, the energy becomes smaller, and by appropriately selecting the constants of the damper 13 and the spring 14, the vibration amplitude can be reduced. If the rotational speed is further increased, a resonance point due to elastic deformation of the rotating shaft will be reached. Since the rotational speed at this resonance point is high, the damper 13 and spring 14 cannot sufficiently absorb the energy, resulting in a large vibration amplitude, and at the same time, the bearing load may exceed the load capacity of the large ball bearing 11. It will be done.

In view of the above points, it is usually preferable to select the rated operating speed to be higher than the resonance point of the rigid body mode and lower than the resonance point of the elastic deformation mode, and this method is adopted. In a separator, if the neck force of the drive shaft increases by 1 due to vibrations such as earthquakes, an increase in the unbalance of the rotating bowl 8, etc., the drive shaft may come into contact with a stationary part and cause a major accident. Ta.

[Objective of the Invention] It is an object of the present invention to provide a centrifugal separator for nuclear fuel reprocessing that is free from the risk of the drive shaft coming into contact with a stationary part due to an earthquake, etc., and is highly reliable even when operated. Objective ○ [Summary of the Invention] The above objective is achieved by making the spherical seat of the bearing tube that supports the drive shaft made of polygon negative metal and impregnating it with oil.

[Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIG. 2, which shows a cross section of a main part. Note that the description of the same parts as in FIG. 1 will be omitted.

In conventional centrifuges, only the damper 13 is used to absorb the neck vibration energy of the drive shaft 9 due to vibrations such as earthquakes.In the present invention, the material of the spherical seat is porous. By using a metal such as a sintered metal and impregnating it with oil, an oil film is always formed at the engaging sliding contact portion. As a result, a type of damper (vibration absorber) is constructed, which is determined by the viscosity of the oil, the thickness of the oil film, and the area of the sliding contact area.

[Effects of the invention] In this way, in addition to the damper, the engaging sliding contact part has a damper function, which improves earthquake resistance and improves the drive shaft without impairing the alignment, which was the initial purpose of the spherical seat. Can maintain stable rotation.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a centrifugal extractor, which is one of the conventional centrifugal separators for nuclear fuel reprocessing, and FIG. 2 is a longitudinal sectional view showing essential parts of an embodiment according to the present invention. 1... Radiation shielding slab, 2... Drive unit, 3...
Wetted part, 8... Rotating bowl, 9... Drive shaft, 10a
...Concave spherical surface, Job...Flange, 12...Bearing tube, 12a...Convex spherical surface, 12b...Flange, machining
... Spherical seat. Agent Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A driving part is provided on the upper side of the slab, and a liquid contact part is provided on the lower side of the slab, and a spherical seat is provided with a bowl that hangs down from the drive part through the slab and rotates within the liquid contact part at the lower end, and is fixed to the slab. 1. A centrifugal separator for nuclear fuel reprocessing, the centrifuge having a rotatable drive shaft in a bearing tube supported by the spherical seat, wherein the spherical seat is made of an oil-impregnated porous metal.