JP3813719B2 - Self-acting furnace stop device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-acting reactor stop device attached to a control rod driving device used for output control of a fast breeder reactor, for example.
[0002]
[Prior art]
The power control of the fast breeder reactor can be carried out by inserting the control rod at a certain depth in the core or withdrawing it from the core. This insertion and withdrawal is connected to the control rod via the control rod desorption mechanism. It is performed by a control rod drive device that operates a drive shaft. In order to maintain the connection between the control rod and the drive shaft, an armature made of a magnetic material provided at the upper end of the control rod is attracted to an electromagnet provided at the lower end of the drive shaft.
[0003]
At the time of the reactor scram, the electromagnet is de-energized to extinguish the magnetic force, the armature is separated from the electromagnet, and the control rod is pulled out. Normally, a Curie-point type electromagnet that is demagnetized at a predetermined temperature is used as an electromagnet of this type of device in order to function as a self-acting furnace stop device. That is, in the unlikely event that the core outlet temperature suddenly rises, the electromagnet becomes its own temperature, the magnetic force disappears at a predetermined temperature, and scram is automatically performed.
[0004]
An example of a conventional control rod driving device is shown in FIG. This control rod drive device has a drive shaft 3 that penetrates the upper biological shield 2 attached to the rotary plug 1, and an electromagnet 4 is provided at the lower end of the drive shaft 3. Further, an armature 6 is provided at the upper end of the control rod 5, and when the electromagnet 4 is excited, the drive shaft 3 and the control rod 5 are connected to each other by the magnetic force. The drive shaft 3 and the control rod 5 are accommodated in the upper guide tube 7 and the lower guide tube 8, respectively.
[0005]
Further, the control rod driving device includes a maintenance latch mechanism 13 including a drive mechanism including a ball screw 10 and a ball nut 11 that transmits the power of the drive motor 9 to the drive shaft 3 and a latch motor 12 on the upper biological shield 2. I have. Further, a position detector 14 for detecting the position of the control rod 5 and a load detector 15 for detecting a load when the drive shaft 3 is driven are provided. Each element provided on the upper biological shield 2 is accommodated in a housing 16.
[0006]
Using such means, for example, when the ball screw 10 is rotated by starting the motor 9, the drive shaft 3 is driven upward or downward via the ball nut 11, and as a result, the control rod 5 is driven to the drive shaft. It follows the movement of 3 and moves in the same direction. At the time of maintenance, the latch mechanism 13 is released by driving the latch motor 12 and can be disconnected from the drive shaft 3. In the figure, reference numeral 17 denotes a cover gas seal that seals the inner region of the pressure vessel from the external space.
[0007]
[Problems to be solved by the invention]
The above-mentioned self-actuated furnace stop device has been proved that the holding force of the electromagnet 4 is sufficiently high for a certain period from the start of operation and that the stop operation is proper, and there is no problem. However, in general, although the electromagnet 4 has a long service life, it is expected that the electromagnet 4 will deteriorate after a certain period of time. Therefore, the holding force is measured during the service period, and the stopping operation is performed. It is desirable to test the electromagnet 4 with simulation conditions.
[0008]
In order to measure the holding force of the electromagnet 4, the instrument must be attached to the related equipment, but the conventional furnace stop device lacks such considerations, and the measurement can hardly be performed. On the other hand, in the stop operation test, it is necessary to heat the electromagnet 4 and gradually increase it to the Curie point temperature, and when it reaches that temperature, it is necessary to confirm that the armature 6 actually departs by demagnetization. Is not equipped with any heating means or the like, and a stop operation test cannot be performed.
[0009]
Therefore, the object of the present invention is to make it possible to measure the holding force between the electromagnet and the armature while maintaining the same conditions as the actual machine in the fast breeder reactor, and to perform the stop operation test at a desired temperature. An object of the present invention is to provide an operation type furnace stop device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is provided inside a top guide tube concentrically with a guide tube, and has a drive shaft having an electromagnet for attracting an armature of a control rod at the lower end, A collar having an annular disk that is slidable along the outer surface and has an outer peripheral edge facing the inner surface of the upper guide tube, and a rod that is connected to the lower end of the collar and extends through the electromagnet to the armature A push rod, an elastic body provided on the push rod and biasing the push rod toward the lower end of the collar, a planar heating element provided along the inner surface of the upper guide tube and heating the electromagnet and the armature, and the heating It is provided with an engagement portion provided on the inner surface of the upper guide tube deeper than the element and provided so as to be able to engage with a collar disk following the movement of the drive shaft.
[0011]
In the furnace stop device configured as described above, the electromagnet can be separated from the armature by independently operating the drive shaft at the stationary position of the collar and the push rod. The moment when the electromagnet leaves the armature is measured by a load detector provided in the control rod driving device. As a result, the holding force can be measured while maintaining the same conditions as the actual machine in the furnace, and the obtained data can be highly reliable.
[0012]
In this furnace stop device, the electromagnet and the armature can be heated to a desired temperature, that is, the Curie point temperature, by the planar heating element provided on the inner surface of the upper guide tube. At this Curie point temperature, the electromagnet is demagnetized, the disappearance of the magnetic force separates the electromagnet from the armature, and the control rod is pulled out. As a result, the stop operation test can be accurately performed in the fast breeder reactor, and the replacement timing of the electromagnet and the armature can be accurately determined.
[0013]
The invention according to claim 2 is characterized in that a coil-like heating element is provided in the rod of the push rod.
[0014]
In the furnace shutdown device configured as described above, the electromagnet and the armature can be heated from inside and outside by the coiled heating element in the rod in addition to the planar heating element, and the temperature distribution is kept uniform in each part of the electromagnet and the armature. It becomes possible to do.
[0015]
Furthermore, the invention according to claim 3 is characterized in that a heat insulating space is formed between the inner surface of the guide tube and the planar heating element.
[0016]
In the furnace stop device configured as described above, heat can be effectively prevented from being lost outside through the wall of the upper guide tube during heating of the electromagnet and the armature by the heat insulating space.
[0017]
The invention according to claim 4 is characterized in that the disk of the collar and the engaging portion are formed in a shape that can be brought into close contact with each other.
[0018]
In the furnace stop device having the above-described configuration, the collar disk is in contact with the engaging portion of the upper guide tube, and the high temperature gas is prevented from rising and flowing out of the upper guide tube 22 in the upper guide tube. be able to.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 3, a drive shaft 18 extending downward through the upper biological shield 2 has an electromagnet 19 at the lower end thereof. The lower end of the electromagnet 19 is in contact with the armature 6 provided at the upper end of the control rod 5, and the drive shaft 18 and the control rod 5 are connected to each other by excitation of the electromagnet 19. Further, the drive shaft 18 includes a collar 20 that is provided at a distance from the electromagnet 19. The inner surface of the collar 20 is loosely fitted to the outer surface of the drive shaft 18 and is configured to be slidable with respect to each other. The lower end of the collar 20 is provided with a later-described connecting piece that protrudes in the radial direction from the inner surface, and the collar 20 and the push rod 21 are connected to each other through the connecting piece.
[0020]
FIG. 1 shows details of the collar 20 and the push rod 21. The collar 20 has an annular disk 23 at the center in the axial direction. The outer peripheral edge of the disk 23 faces the inner surface of the upper guide tube 22 that surrounds the drive shaft 18, and the shape thereof is formed in accordance with the shape of the convex portion of the upper guide tube 22 described later.
[0021]
Further, the collar 20 is provided with three connecting pieces 24 projecting in the center direction from the inner surface at the lower end thereof. Further, the push rod 21 includes a head portion 25 in contact with the connecting piece 24 at the upper end and a rod 26 extending downward from the head portion 25. The rod 26 is inserted into the center hole 27 of the electromagnet 19, and the tip of the rod 26 is fitted with a pin hole 28 formed in the upper surface of the armature 6 so as to function as a positioning center pin.
[0022]
Further, the push rod 21 surrounds the rod 26 and is pressed against the connecting piece 24 by a spring 29 attached between the head portion 25 and the upper surface of the electromagnet 19. The push rod 21 includes a coil-shaped heater 30 made of nichrome wire in the rod 26. The coil heater 30 is connected to a power source via a lead wire (not shown).
[0023]
On the other hand, as shown in FIG. 2, the upper guide tube 22 is provided with a sleeve 32 by forming an annular heat insulating space 31 between the upper guide tube 22 and the inner surface thereof. The sleeve 32 extends long along the tube axis direction, and is provided with a planar heater 33 on the inner surface thereof. The planar heater 33 is connected to a power source via a lead wire (not shown).
[0024]
Further, a long hole 34 is formed through the wall surface in the drive shaft 18 to pass the three connecting pieces 24 of the collar 20. The long holes 34 are formed along the axial direction of the drive shaft 18 in order to allow the collar 20 to move.
[0025]
Further, the inner surface of the upper guide tube 22 is in contact with the disk 23 of the collar 20 at a deeper position than the planar heater 33, and a convex portion 35 for separating the electromagnet 19 from the armature 6 at the time of holding force measurement (see FIG. 1). Is provided. The convex portions 35 are formed in a shape that can be brought into close contact with each other following the outer peripheral edge shape of the disk 23.
[0026]
The present embodiment is configured as described above, and when measuring the holding force, when the ball screw 10 is rotated by starting the drive motor 9, the drive shaft 18 is raised, and the collar 20 and the push rod 21 are moved upward accordingly. . At this time, the electromagnet 19 is in an excited state, and the control rod 5 on which the armature 6 is attracted to the electromagnet 19 is also raised at the same time. When the drive shaft 18 continues to rise, the disk 23 of the collar 20 hits the convex portion 35 of the upper guide tube 22, and at this time, the movement of the collar 20 and the push rod 21 is restricted.
[0027]
As shown in FIG. 4, the drive shaft 18 can operate independently at the stationary position of the collar 20 and the push rod 21, and the electromagnet 19 can be separated from the armature 6. That is, it is possible to measure the moment when the electromagnet 19 leaves the armature 6 while maintaining the excited state under the same conditions as the actual machine. The holding force is measured using the load detector 14.
[0028]
In the prior art, it was impossible to measure the holding force of the electromagnet 19 while reproducing the conditions of the actual machine in the furnace. However, in this embodiment, the holding force is maintained while maintaining the same conditions as the actual machine in the furnace. Can be measured, and the obtained data can be highly trusted. In addition, this measuring method can be measured by a very simple means comprising a combination of the convex portion 35 of the upper guide tube 22, the collar 20, and the push rod 21, and is a large-scale measuring device including installation of a load measuring instrument. Is also economically advantageous.
[0029]
Further, during the stop operation test, when the ball screw 10 is rotated by starting the drive motor 9, the drive shaft 18 is raised, and the collar 20 and the push rod 21 are simultaneously moved upward. At this time, the armature 6 is attracted to the electromagnet 19 and the control rod 5 is also raised simultaneously. When the drive shaft 18 continues to rise, the disk 23 of the collar 20 hits the convex portion 35 of the upper guide tube 22, and at this time, the movement of the collar 20 and the push rod 21 is restricted.
[0030]
In this state (see FIG. 5), the electromagnet 19 and the armature 6 are heated by energizing the planar heater 33 and the coil heater 30. Due to the heating from the inside and outside, the temperatures of the electromagnet 19 and the armature 6 rise rapidly, and both reach the Curie point temperature (about 640 ° C.). Since the electromagnet 19 is demagnetized at the Curie point temperature, the electromagnet 19 and the armature 6 are separated by the disappearance of the magnetic force, and the control rod 5 is dropped and inserted into the core. In other words, it is possible to create a situation similar to a reactor scram.
[0031]
Therefore, for example, when normal operation occurs around the Curie point temperature, it can be confirmed that no deterioration occurs in the electromagnet 19 and the armature 6, and when the operation is not performed near this temperature. It can be determined that the electromagnet 19 and the armature 6 have some kind of deterioration or similar abnormality.
[0032]
As described above, in this embodiment, the stop operation test can be accurately performed in the fast breeder reactor, and based on this result, it is possible to accurately determine the replacement timing of the electromagnet 19 and the armature 6.
[0033]
Furthermore, the electromagnet 19 and the armature 6 can be heated from inside and outside, and heating can be performed while maintaining a uniform temperature distribution in each part.
[0034]
Further, heat can be effectively prevented from being lost outside through the tube wall of the upper guide tube 22 during heating by the heat insulating space 31 outside the planar heater 33.
[0035]
Furthermore, since the disk 23 of the collar 20 is heated while being in contact with the convex portion 35 of the upper guide tube 22, it is prevented that, for example, sodium gas rises and flows out of the upper guide tube 22. be able to.
[0036]
Further, the tip of the rod 26 of the push rod 21 functions as a positioning center pin to facilitate positioning of the electromagnet 19 and the armature 6. This makes it possible to minimize electromagnet design changes and make use of previous knowledge.
[0037]
【The invention's effect】
As described above, the present invention can measure the holding force between the electromagnet and the armature while maintaining the same conditions as the actual machine in the fast breeder reactor, and on the other hand, the stop operation test under the desired Curie point temperature. Can be implemented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a self-acting furnace stop device according to the present invention.
2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a cross-sectional view showing a control rod driving apparatus according to the present invention.
FIG. 4 is an operation explanatory diagram at the time of holding power measurement of the self-acting furnace stop device.
FIG. 5 is an operation explanatory diagram during a stop operation test of the self-acting furnace stop device.
FIG. 6 is a cross-sectional view showing a conventional control rod driving device.
[Explanation of symbols]
5 Control rod 6 Armature 18 Drive shaft 19 Electromagnet 20 Collar 21 Push rod 30 Coil heater 33 Planar heater 35 Convex part

Claims (4)

A drive shaft provided concentrically with the guide tube inside the upper guide tube and having an electromagnet that attracts the armature of the control rod at the lower end, and provided slidably along the outer surface of the drive shaft. A collar having an annular disk facing the inner surface of the upper guide tube, a push rod having a rod connected to the lower end of the collar and extending through the electromagnet and extending to the armature, and the push rod. , An elastic body that urges the push rod toward the lower end of the collar, a planar heating element that is provided along the inner surface of the upper guide tube and that heats the electromagnet and the armature, and a deeper depth from the heating element. A self-acting furnace comprising an inner surface of an upper guide tube and an engagement portion provided to be able to engage with the disk of the collar following the movement of the drive shaft Stop apparatus. 2. The self-actuating furnace stop device according to claim 1, wherein a coiled heating element is provided in the push rod. 2. The self-actuating furnace stop device according to claim 1, wherein a heat insulating space is formed between the inner surface of the guide tube and the planar heating element. 2. The self-acting furnace stop device according to claim 1, wherein the disk of the collar and the engaging portion are formed in a shape capable of being in close contact with each other.

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