JPH0636058B2 - Self-actuated electromagnet for control rod retention mechanism - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a self-actuating electromagnet for automatically inserting control rods into a core for emergency shutdown of a reactor when an abnormality occurs,
More specifically, the present invention relates to a self-actuating electromagnet for a control rod holding mechanism, which is provided with a mechanism in which an iron core having a two-divided structure surely comes into contact with each other at both adsorbing portions to prevent erroneous operation of holding and disconnecting a control rod. It is a thing.

[Prior Art] Generally, a fast reactor or the like is provided with a mechanism for inserting a control rod into the core in the event of an abnormality in order to enhance the reliability of reactor shutdown. In order to increase the reliability of this mechanism, a configuration has been proposed in which a self-actuating electromagnet is incorporated so that the reactor can be safely shut down without depending on external operations or signals.

As a control rod holding mechanism of this type, there is a structure as shown in FIG. 3A, for example. A control rod 10 having a neutron absorber is positioned and held in a guide tube 12 in the core. The control rod holding mechanism includes a drive shaft 14 and a self-actuating electromagnet 16 located at the lower end of the drive shaft 14, and holds the control rod 10 by the magnetic attraction force of the electromagnet 16.

The conventional self-actuating electromagnet 16 includes the first and second iron cores 1.
Iron core with a two-part structure combining 8 and 20, and coil 2
2 and the temperature-sensitive magnetic material 24 is incorporated in a part of the magnetic circuit. Reference numeral 26 indicates a non-magnetic connecting member.

The self-actuating electromagnet 16 is placed in the high temperature coolant near the core. Therefore, if any abnormality occurs in the furnace, the ambient temperature rises, and the temperature-sensitive magnetic material 24 loses its magnetism in response to the abnormal temperature, so that the magnetic attraction force between the iron cores 18 and 20 is reduced. , The control rod 10 is separated as shown in FIG. 3B and falls by its own weight to stop the reactor.

[Problems to be Solved by the Invention] As described above, in the self-actuating electromagnet, the iron core constituting the magnetic circuit has a two-divided structure so that adsorption and separation can be performed. In the prior art, since each of the divided iron cores is integrally processed, it is extremely difficult in terms of precision of mechanical processing to bring the two adsorbing portions (represented by reference numerals 1 and II) into contact with each other without causing a gap. is there. In reality, it is inevitable that a gap of about 0.1 mm will occur in either of the suction portions. Since the magnetic attraction force between the split iron cores 18 and 20 is strongly influenced by the gap size, the variation of the magnetic attraction force between electromagnets becomes large.

In this type of electromagnet 16, the magnetic attraction force becomes sufficiently smaller than the own weight of the control rod when the temperature is abnormal, and conversely, it is necessary to make it sufficiently larger than the own weight of the control rod during steady operation. Therefore, it is necessary to design the magnetic attraction force to a value within a certain narrow range in consideration of the balance between the two. However, the above variation makes this design difficult and causes a malfunction.

At present, the magnetic attraction is only adjusted by the value of the current flowing through the coil, but it is desirable to magnetically relax the temperature-sensitive magnetic material in order to improve the operating performance. For this purpose, it is necessary to pass a sufficiently large current. The adjustment of the magnetic attraction force by controlling the current value brings about a result of sacrificing the responsiveness.

Further, if there is a gap in the attracting portion between the iron cores, magnetic impurities may intrude and deposit there, causing a problem of adversely affecting the magnetic properties of the electromagnet.

The object of the present invention is to solve the above-mentioned drawbacks of the conventional technology and to make it possible to reproducibly exhibit the magnetic attraction capability originally possessed by the electromagnet, thus reducing the risk of malfunction during steady operation and abnormal temperature. The control that can reliably perform the control rod disconnection operation at the time, and also prevents the magnetic impurities from entering and depositing in the adsorption part between the iron cores, thereby significantly improving the reliability of the furnace shutdown. To provide a self-actuating electromagnet for a rod holding mechanism.

[Means for Solving the Problems] In the present invention which can achieve the above-mentioned object, the two are mutually adsorbed.
It is equipped with first and second iron cores that have magnetic attraction parts and that form a magnetic circuit by combining both magnetic attraction parts, and a coil, and incorporates a temperature-sensitive magnetic material in a part of the magnetic circuit to keep the ambient temperature. In an electromagnet that holds and separates the control rods accordingly, a mechanism in which, for either one of the adsorption portions, a part of one iron core including the adsorption surface is movable in the control rod axial direction with respect to the other portion. Is a self-actuating electromagnet for a control rod holding mechanism, in which the iron cores are in contact with each other at the same time in both adsorption portions.

Here, as a preferable configuration, a part of the iron core is screwed to the other part, and by relatively rotating, the iron cores can be finely adjusted so that the iron cores are always in contact with each other at both adsorption portions. There is something I did.

[Operation] In the configuration in which each of the divided iron cores is integrally machined, it is extremely difficult to bring the iron cores into contact with each other at both of the two suction portions in terms of precision of mechanical processing. However, in the present invention, a part of one iron core including one attraction surface is movable in the control rod axial direction with respect to the other part, so that the iron cores simultaneously contact with each other in both attraction parts. Can be adjusted to This makes it possible to maximize the magnetic attraction capability of the electromagnet with good reproducibility. Therefore, it is not necessary to control the adjustment of the magnetic attraction force by the coil current value, and the risk of malfunction of holding and disconnecting the control rod is reduced.

In addition, since the gap between the iron cores is eliminated in the adsorption portion, invasion and deposition of magnetic impurities can be prevented, and the magnetic properties of the electromagnet do not change.

For these reasons, the reliability of reactor shutdown in an emergency will be greatly improved.

[Embodiment] FIG. 1 is an explanatory view showing an embodiment of a self-actuating electromagnet for a control rod holding mechanism according to the present invention.

The self-actuating electromagnet includes a first iron core 30, a second iron core 32, and a coil 34. The first iron core 30 has a structure in which a central cylindrical portion 30a and an outer upper cylindrical portion 30b are continuously integrated in the upper portion. The second iron core 32 connects the upper cylindrical portion 40 and the lower cup-shaped portion 42 with a non-magnetic material 44, and adheres to the outer surfaces of the cylindrical portion 40 and the cup-shaped portion 42 so as to surround them. Then, the temperature-sensitive magnetic material 46 in a cylindrical state is provided.

Now, the present invention is significantly different from the prior art in that both iron cores 3
This is the structure of the adsorption portions I and II between 0 and 32. In the present invention, a part of the one adsorbing part including one adsorbing surface of one iron core is configured to be movable in the control rod axial direction with respect to the other part. The point is that they always contact each other.

In this embodiment, such a position adjusting mechanism is provided in association with the second suction section II. That is, the screw iron core 48 is provided and screwed so as to penetrate the bottom surface of the cup-shaped portion 42. By rotating the screw iron core 48, the tip end surface and the columnar portion 30 a of the first iron core 30 are rotated. The gap with the bottom surface can be adjusted.

To assemble such a self-actuated electromagnet, the following procedure is performed. First, lower the screw iron core 48 to the second suction portion.
In step II, the iron cores are prevented from contacting each other, and the first iron core 30 and the second iron core 32 are combined. Here, the electromagnet coil 34 is energized to attract the first iron core 30 and the second iron core 32. Next, the screw iron core 48 is gradually rotated and raised so that the upper surface of the screw iron core 48 has the cylindrical portion 30 of the first iron core 30.
a Search for a position that contacts the bottom surface. This position is a position where the iron cores 30 and 32 are simultaneously in contact with each other in the attraction portions I and II, and is a position where the maximum magnetic attraction force, that is, the designed magnetic attraction force of the electromagnet is obtained. .

Although the iron cores 30 and 32 divided by this are manufactured separately, the iron cores can be easily adjusted so that the iron cores always come into contact with each other in both suction portions I and II when the both are combined. .

FIG. 2 is a diagram showing the relationship between the rotation angle of the screw iron core 48 and the magnetic attraction force, and the horizontal axis represents the gap size in terms of the rotation angle. The contact position is at a rotation angle of 0 degree. In the case of the integrally machined electromagnet, the range of the magnetic attractive force is generally within the range indicated by the diagonal lines, and the magnetic attractive force has a considerable variation even if the mechanical processing accuracy is increased. However, in the present invention, since the contact state is established, the magnetic attraction force can be set high without any flicker.

Although one embodiment of the present invention has been described in detail above, it is needless to say that the present invention is not limited to such a configuration, and that the configuration of the magnetic circuit of the electromagnet can be appropriately changed according to usage conditions and the like. .

[Effect of the Invention] As described above, the present invention is a self-actuating device that is provided with a mechanism in which a part of one iron core including one attraction surface is movable in the control rod axial direction with respect to the other attraction part as described above. Since it is a die-type electromagnet, it is possible to bring the iron cores into contact with each other at two adsorbing portions at the same time, and it is possible to obtain a higher adsorbing force than that of the integrally machined electromagnet in which a gap is formed in one adsorbing portion. In the electromagnet of the present invention in which both the attracting portions are in contact at the same time, since the value of the magnetic attraction force is almost equal to the design value and there is little variation, it becomes easy to set the magnetic attraction force with respect to the weight of the control rod, It is possible to prevent erroneous operation of holding the control rod in, and to perform a reliable disconnection operation at abnormal temperature,
With these, the reliability of the self-actuated reactor shutdown mechanism can be improved.

In particular, in the configuration in which a part of the iron core is screwed to the other part, the degree of contact between the iron cores can be easily adjusted, and the assembling workability is also improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a self-actuating electromagnet according to the present invention, FIG. 2 is a diagram showing a relationship between a rotation angle of a screw iron core and a magnetic attraction force, and FIGS. 3A and 3B. FIG. 6 is an explanatory view showing an example of a control rod holding mechanism and its operation. 16 ... Self-actuated electromagnet, 30 ... first iron core, 32
…… Second iron core, 34 …… Coil, 44 …… Non-magnetic material,
46: Temperature-sensitive magnetic material, 48: Screw iron core.

Claims (2)

[Claims] 1. A two-part suction part that sticks to each other,
It has first and second iron cores that form a magnetic circuit by combining them at both adsorption parts, and a coil, and incorporates a temperature-sensitive magnetic material in a part of the magnetic circuit to hold the control rod according to the ambient temperature. In the electromagnet that performs disconnection, for one of the adsorption parts, a mechanism is provided in which a part of one iron core including the adsorption surface is movable in the control rod axial direction with respect to the other part. A self-actuating electromagnet for a control rod holding mechanism, characterized in that the iron cores contact each other at the same time. 2. The self-actuating electromagnet according to claim 1, wherein a part of the iron core including one attraction surface is screwed to the other part.