JPS6340581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crud separation apparatus equipped with a granulator that separates crud in a fluid, such as nuclear reactor coolant, using a magnetic field.

A crud separator is installed in the middle of a reactor coolant pipe and is used to separate and remove crud (fine iron oxide particles such as Fe ₂ O ₃ and Fe ₃ O ₄ ).

In general nuclear reactors, fluids such as light water, sodium, carbon dioxide, helium gas, and reactor coolants are used depending on the type of reactor to extract the heat generated in the reactor core.

By the way, many constituent materials such as high-quality steel are used in nuclear reactor pressure vessels, piping, etc., and due to the effects of erosion caused by radioactive thermal energy during reactor operation, the above-mentioned crud is produced as radioactive corrosion products. It is said that a phenomenon occurs in which the particles are generated, mixed into the reactor coolant, and circulated through the pipes. These cruds are extremely small in quantity and depend on the operating history of the reactor and differences in the constituent materials, but the particle size is approximately 1 to 10 micrometers (μm) and gradually grows. It has been observed that there is a trend. Since these cruds are fine particles, they are thought to have no effect on normal nuclear reactor operation.

However, since the crud is contained in the reactor coolant in a suspended state, the crud settles and accumulates in areas where the flow velocity is slow or during shutdown. These are radioactive products containing CO ⁶⁰ and have a high radiation dose, significantly increasing the air dose. Therefore, it may cause radiation exposure, and adhesion to precision equipment of the nuclear reactor system may impede the operational functions and stability of the nuclear reactor.

The present invention has been made in consideration of the above background,
Focusing on the fact that the crud is a magnetic material, the crud in the reactor coolant is first magnetized and granulated using a DC magnetic field using a high-gradient constant magnetic field, and immediately after that, the crud is granulated using an alternating magnetic field. The objective is to efficiently separate and remove crud by applying a magnetic field to improve the integrity of nuclear power generation facilities.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

In FIG. 1, the reference numeral 1 indicates a granulator, and the granulator 1 includes a magnetization chamber 2 to which reactor coolant (for example, light water) is supplied, and a magnetization chamber 2 containing, for example, about 3000 Gauss. Magnetizing magnetic poles 3A and 3B for applying a high gradient constant magnetic field (DC magnetic field for magnetizing the cladding by applying a sudden strong magnetic field)
and an outlet port 4 through which the cladding, which has become larger in particle size due to mutual magnetization due to magnetization in the magnetization chamber 2, flows out to the next process together with the reactor coolant.

On the other hand, what is indicated by the reference numeral 11 in FIGS. 1 and 2 is a ring-shaped container, and this ring-shaped container 11 is formed between an outer wall 11a and an inner wall 11b of a true cylindrical shape whose axes are vertically aligned. A ring-shaped reaction chamber 12 to which reactor coolant is supplied from the granulator 1 is provided, and is fixed on a support frame 13. The reaction chamber 12 is shielded by a partition wall 14 disposed vertically, and a fluid inlet 15 and a fluid outlet 16 are disposed on both sides of the partition wall 14 in the circumferential direction. The fluid inlet 15 is communicated with the outlet 4 of the granulator 1, and
They are arranged in close proximity so that the communication distance is as short as possible. In addition, the partition wall 14
A cladding reservoir 17 is provided at the bottom of the reaction chamber 12 at a position close to the reaction chamber 12 .

Further, on both sides of the reaction chamber 12 in the radial direction, there are a plurality of magnets (permanent magnets etc.) 18A, 18B, 19 for separating the crud in the reactor coolant.
A and 19B are arranged along the circumferential direction. These magnets 18A, 18B, 19A, and 19B are integrally attached to the outer support frame 20 and the inner support frame 21, respectively, as shown in FIGS. The poles are different (N pole and S pole, or S pole and N pole), and adjacent poles in the circumferential direction are arranged in a relationship such that they are different poles. In the example shown in FIG. 1, the magnet forming one pole is constructed by integrating a plurality of vertically divided blocks.

The support frames 20 and 21 are mounted on the outer guide rail 22 and the inner guide rail 23.
A plurality of magnets 1 are mounted via a plurality of wheels 24.
8A, 18B, 19A, and 19B are configured to rotate while sandwiching the reaction chamber 12. Further, both support frames 20 and 21 are connected by a synchronization mechanism 25 so that the arrangement relationship of the respective magnets shown in FIG. 2 does not change.

This synchronization mechanism 25 includes an external gear 26 that is integrally provided on the outer periphery of the outer support frame 20, a pinion 27 that meshes with the external gear 26, and a pinion 27 that meshes with the external gear 26.
Connecting gears 28 and 29 meshing with 7 and connecting gear 2
9, and the inner support frame 2.
1, and an internal tooth gear 31 that is integrally provided on the inner circumference of the support frame 1 and meshes with a pinion 30, to prevent positional misalignment in the horizontal rotation direction between both rotatable support frames 20 and 21. The structure is not limited to the illustrated structure example.

Further, a drive mechanism 32 is connected to the synchronization mechanism 25, so that each of the magnets rotates synchronously. That is, the drive mechanism 32 is
It consists of a motor 33 and a drive gear 34 that transmits the rotational force of the motor 33 to the pinion 27,
For example, the structure is such that a strong magnetic field is applied to the crud in the reactor coolant at a rate of about 3 to 10 times per second.

The operation of the clad separation device constructed as described above will be explained below.

When reactor coolant containing crud is fed into the granulator 1, the crud is magnetized by a high gradient constant magnetic field and converges near the magnetic field, and the magnetization causes the crud particles to become magnetically attached to each other. The crud condenses in a "whisker" shape, causing local differences in the density of crud in the reactor coolant. When the "whisker" shaped crud is sent out from the magnetization chamber 2 by turning the granulator power ON and OFF, it becomes unaffected by the magnetic field, but due to the residual magnetism given to each grain of the crud, it becomes mutually magnetic. The particles are transported from the delivery port 4 to the fluid inlet 15 of the reaction chamber 12 in a "beard"-like granulated state.

According to the example, the size of the clad mass granulated in this way is that the size of one clad particle is 1 to 4 μm, and when passed through a high gradient constant magnetic field of 3000 Gauss, the clad mass is Most of 15μm
Granulation resulting in the above clad lumps was observed. On the other hand, it is expected that the granulated crust mass will be gradually disintegrated (decomposed) due to the flow rate of the coolant, etc., and that the density of the densely packed crust will gradually average out.

Therefore, the communication distance between the granulator 1 and the fluid inlet 15 is shortened as much as possible, and the granulated crust mass or densely packed crust is fed into the reaction chamber 12. At this time, according to the inventor's experiments, when a 15 μm clad mass is conveyed over a distance of 200 mm by a flow of reactor cooling water at a speed of 233 mm/sec, 40% of it is disintegrated; It was observed that the cruts formed in groups and were densely packed together.

Next, to explain the case where the reactor coolant containing the crud mass is sent into the reaction chamber 12 from the fluid inlet 15, the crud mass or the crud mass is suspended in the reactor coolant in a disaggregated state. Since an alternating traveling magnetic field acts on a group of cruds, the cruds are magnetized again and collected near the partition wall 14 along the direction of rotation of the magnet, and then transferred to the crud storage section 17 by the traveling magnetic field and collected. That will happen.

The magnetic field created by the magnet for generating a traveling alternating magnetic field is 2000~
Since the magnetic field is as high as 3000 gauss, it undergoes a granulation effect and combines with the traveling magnetic field, causing clusters of crud or crud clustered together in the vicinity to form “beards” one after another as if holding hands in adjacent directions. The magnetic field extends in a shape and is further aligned in the direction of the traveling magnetic field between the different poles. This alignment of the cladding is more efficient than when the cladding is uniformly distributed, and the cladding comes close to the outer wall 11a or the inner wall 11b, as shown by C in FIG. moreover,
Since each magnet is rotated by the drive mechanism 32, the aligned cladding tends to move with the traveling magnetic field against the fluid resistance (viscosity) of the reactor coolant. In this case, the rotation speed of the magnet is fast enough to apply an alternating magnetic field of about 3 to 10 Hz to one point of the reaction chamber 12, so there is a delay in the movement of the cladding, which causes it to come into contact with the partition wall 14 in the rotation direction. is driven little by little. Hereinafter, the crud collected in the crud storage section 17 is taken out and processed as appropriate.

Note that each magnet may be an electromagnet (direct current or alternating current) instead of a permanent magnet.

As is clear from these descriptions, according to the present invention, the following effects can be achieved.

If crud is mixed in the reactor coolant, it can be separated and removed in the middle of the circulation path.
The health of nuclear power generation facilities can be improved.

By granulating the crud in advance using a high-gradient constant magnetic field, the magnetic retention increases against external magnetic fields, making it easier to behave in the presence of a traveling magnetic field, etc., and even fine particles of crud can be efficiently separated and removed. It is possible to improve the removal rate.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line - in FIG. 1. 1... Granulator, 2... Magnetization chamber, 4... Delivery port,
11...Ring-shaped container, 11a...Outer wall, 11
b...Inner wall, 12...Reaction chamber, 15...Fluid inlet, 16...Fluid outlet, 17...Clad reservoir, 18A, 18B, 19A, 19B...Magnet,
20...Outer support frame, 21...Inner support frame, 25
...Synchronization mechanism, 32...Drive mechanism.

Claims (1)

[Claims] 1. A fluid clad separation device, which includes a granulator that introduces a fluid into a high-gradient constant magnetic field, promotes the granulation action of the clad, and sends it out, and a fluid inlet that is connected in close proximity to the granulator. 1. A crud separation device equipped with a granulator, characterized in that a reaction chamber is connected to the fluid containing granulated crud in an alternating traveling magnetic field to separate the crud.