JPS59112282A - Control rod drive mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a nuclear reactor control system suitable for safely and reliably shutting down a reactor in the event of an accident in a liquid totally refractory cooled fast breeder reactor. It relates to a rod drive device.

[Technical Background of the Invention] The well-known nuclear reactor is a device that causes a nuclear fission reaction by neutrons to occur under controllable conditions, thereby extracting energy to be released. .

Nuclear reactors include fast neutron reactors, which use nuclear fission to produce neutrons with an energy of approximately 0.1 (Me V) or higher, and nuclear fission reactors, which produce neutrons with an energy of approximately 0.1 (Me V) or less and have a thermal neutron energy or higher. J on medium-speed neutron reactors and thermal neutrons
Among the above reactors, the fast neutron I reactor, which maintains a chain reaction in the nuclear fission of fast neutrons, produces nuclear fission caused by neutrons and produces 14 fission substances. Nuclear fuel containing nuclear fuel, coolant which is a fluid to extract the heat generated as a result of nuclear fission, and prevention of leakage of neutrons from the reactor core in order to utilize neutrons economically -C
It consists of a reflector, a chain reaction control system, and shielding to reduce radiation from the core to an acceptable level.

Among the above-mentioned components, the control device has a particularly important role in operating the reactor, and it not only adjusts the output due to the chain reaction, but also quickly responds when an abnormality occurs in the reactor. has the ability to stop chain reactions. The control device consists of a control rod containing a neutron absorbing substance such as boron or tantalum, a control rod drive mechanism that connects with this control rod and moves it into and out of the reactor core, and a control rod drive mechanism that combines the control rods and the control rod drive mechanism. It consists of a drive section for performing the lifting and lowering operations, and a control panel for transmitting electrical signals to this drive section.

FIG. 1 shows an example of the control rod drive device described above. The drive housing 1 is connected to an upper guide tube 3 fixed on a rotary plug 2 for closing the upper end opening of the reactor vessel. A motor 4 is provided at the top of the drive unit housing 1 , and the motor 4 is electrically coupled to a control panel 6 via a cable 5 . A screw 7 is concentrically connected to the rotating shaft of the motor 4, and a pole nut 8 is screwed onto the screw 7. The pole nut 8 is connected to a pair of load cells 10 via a plate 9, and the load cell 10 is connected to a hollow disc-shaped plate 11. An electromagnet 12 and a cylinder 13 are coupled to the lower surface of the plate 11. The lower part of the cylinder 13 is connected to a pair of [1-docels 14], and the lower part of the load cell 14 is connected to an outer extension tube 15. The outer extension pipe 15 penetrates the rotary plug 2 and is installed in the reactor core 16.
The lower guide tube 17 is extended upward, and its tip forms a plurality of leaf spring-shaped tachi fingers 20 to form a latch mechanism together with one finger rod at the lower end of the inner extension tube 18. .

On the other hand, a magnetically removable armature 21 is provided below the electromagnet 12 electrically connected to the control panel 6, and is attached to the inside of the outer extension pipe 15 with an appropriate gap. The inner extension tube 22 and the outer extension tube 15 are fixed to the top of the inner extension tube 22.The inner extension tube 22 forms a double tube shape with the outer extension tube 15, passes through the corresponding position of the rotary plug 2, and the tip thereof is connected to the latch finger 20. finger rod 1 that engages with
It is 8. A bioshield 23 is fixed to the top of the upper guide tube 3 at a position corresponding to the rotary plug 2 between the upper guide tube 3 and the outer extension tube 15, and the lower end of the bioshield 23 and the outer extension The tube 15 is airtightly connected to an appropriate position with a long rose 24 to isolate the atmosphere inside the furnace from the outside of the furnace. Furthermore, bellows 25 are provided at appropriate locations on the inner extension tube 22 and the outer extension tube 15, respectively, with both ends hermetically joined. Outer extension tube 15
An acceleration spring 27 is coupled to the stepped portion 26 of the accelerating spring 27, which extends downwardly on the outside of the outer extension tube 15 in the form of a coil spring, and has its lower end in contact with the head of the acceleration tube 28. The acceleration tube 28 is installed outside the outer extension tube 15, and its lower end is in contact with the handling head 30 of the control rod 29, and the lower surface of its upper end is supported by a damping spring 31. The lower end of the damping spring 31 is supported by a stopper 32 fixed near the lower end of the upper guide tube 3. The control rod 29 has a structure in which a plurality of absorption bottles containing neutron absorbing material are stacked one on top of the other and housed in a protection tube. An appropriate gap is provided between the rod 29 and the lower guide tube 17.

The operation of the conventional control rod drive device having the structure as described above will be described below. During normal operation, the handling head 30 of the control rod 29 is connected to the shoulder of the latch fin car 20 as shown in FIG. 1, and the control rod 29 is connected to the outer extension pipe 15. The inner surface of the latch finger 20 is restrained by the finger rod 19. At this time, the armature 21 is attracted to the electromagnet 12 by magnetic force and comes into contact with the electromagnet 12. Further, the acceleration spring 27 is in a compressed state with its upper end being restrained by the stepped portion 26 of the outer extension tube 15 and its lower end being restrained by the head of the acceleration spear 28 which is restrained by the handling spatula 30 of the control rod 29. .

To adjust the core output in this state, i+'l 131
1' The motor 4 is rotated by manually operating the JK 6 or by sending a signal for forward or reverse rotation to the motor 4 using the automatic operation circuit in the panel, and the rotational movement is performed by the Scrico-7 and the pole nut 8. This is done by the bed or insertion of the control rod 29 which is translated into an up and down movement.

Now, if an abnormal condition occurs in the plant for some reason, such as a drop in cold H1 material flow, a rise in coolant temperature, or a failure in the reactor core, J will detect the failure at a center (not shown). The signal is transmitted to the control panel 6 by the signal FA33. The control panel 6 automatically generates a scram command signal according to the operation of the operator or the operator using a logic circuit configured in advance, and stops energizing the electromagnet 12. When the electromagnet 12 is deenergized, the armature (・2
1 is cut off and falls by the gap between it and the plate-shaped portion at the lower end of the tube 13. As a result, all the inner extension tubes 22 fall, and the finger rond 19 falls, releasing the latch finger 20 from its restraint. 1. Therefore, the latch finger 20 is compressed inward by the restoring force of the leaf spring and disengages the control rod 29 from the handling head 30.

The control rod 29 rapidly falls through the lower guide tube 17 under the force of the acceleration spring 27 which is transmitted to the acceleration tube 28 due to gravity.

The scram operation of the control rods is achieved through the above steps.
The long bellows 2'l 83 and the bellows 25 enable axial movement of the outer extension tube 15 and the inner extension tube 22,
It is also used for the purpose of isolating the surrounding air inside the furnace vessel. In addition, the loadrel 10 and the load cell 14 are control drive i8
It is used for the purpose of confirming the integrity of the I device.

Generally, a control rod drive device consisting of an electromechanical drive mechanism, typified by the conventional control rod drive device described above, and a control panel equipped with sensors and electrical logic circuits is I'll have sufficient reliability and reliable operation.
It can be said that it is something that can be used by the samurai and is sufficiently effective in maintaining the safety of the nuclear reactor.

[Problems with failed technology] However, when a very high level of safety is required due to the miniaturization of nuclear reactors and the increase in output, completely different equipment is required in addition to the conventionally used equipment. It is believed to be advantageous to introduce a reactor shutdown device operated by means. The reason for this is that the probability of a hypothetical situation in which a failure occurs in the reactor protection system and makes it impossible to effectively shut down the reactor can be increased by increasing the safety margin by making conventional equipment hyperactive. h is more effective when a different type of reactor shutdown device is used in combination than using the method. To this end, it is necessary to eliminate common cause failures with conventional equipment as much as possible.
: A nuclear reactor shutdown device is desired (of course, nuclear reactors must be equipped with all possible measures to prevent them from causing a public disaster under any circumstances).

``Object of the Invention'' The present invention was made in view of the above circumstances, and its purpose is to ensure that even if the control rods are latched normally due to thermal bending or the like, the reactor core It is equipped with a self-insertion function that automatically inserts into the reactor core when the thermal output suddenly increases, and further improves the safety of the reactor by being able to detect the position of the control rod when it falls. Our goal is to provide rod drive equipment.

[Summary of the Invention In other words, the control rod drive device of the present invention includes a IIJ III rod drive device J3 that has a latch mechanism for vertically moving or separating the control rods during reactor power adjustment and emergency shutdown. , a latch finger link type is used for attaching and detaching the control rod, and a detachment mechanism consisting of magnets 1 to 1 and an armature is provided on the soil part of the latch finger in order to scatter the control rod by means of this link type unclawing ringer, and the link type The present invention is characterized in that an operating rod is provided on the lower surface of the armature for opening and opening the type latch fingers.

Furthermore, the present invention allows the control rods to be latched normally without being affected by thermal curvature or eccentricity, and it is also possible to confirm whether the control rods have been completely scrammed, contributing to improved safety. J゛ru.

[Embodiments of the Invention] The details of the present invention will be explained below with reference to the drawings for each embodiment.

FIG. 2 is a cross-sectional view of the vicinity of the reactor core when the control rod drive unit K according to the present invention is installed in a fast breeder nuclear reactor.

In FIG. 2, a latch mechanism 40 is provided at the lower part of the outer extension tube marked @15. The latching mechanism 40 includes a linked wrap-finger/11 that can engage the control rod handling head 30 and an inner extension tube 22 that maintains the linked latching finger 41 in an open position and closes the control rod 29 to the lB2 shield V. The magnet l-I installed at the bottom of the
! l-2 and an arm 43 provided at the top of the link type latch finger 41.
It consists of an operating rod 44 for smoothly opening and expanding the link type latch fingers/11.

Further, at the lower end of the inner extension tube 22, a center 45 for detecting the position of the control rod 29 is provided by penetrating the latch device 4f840.
A magnet 1-46 for indicating the position of the control rod 29 is arranged inside the control rod 29.Next, the principle of operation of the control rod drive device will be explained.

When you go to grab the control rod 29 during operation of the reactor, the armature 43 is lowered to the position of the support plate 17, so the armature 43 is housed in the finger case 48. It has become a shape part. In this state, the inner and outer extension tubes 2 are driven by the drive motor shown in the figure.
2.15 is lowered at the same time. When the extension tube 15 descends to a certain position, the tip of the operating rod 471I comes into contact with the top surface of the control rod handling head 30, and the armature 43 moves down the support plate 47 by -1. From l! By pressing the lower surface J of the sliding magnet 7I2, the link type latch fin force 41 which is interlocked with this armature t43 is also expanded. Thereafter, when the lower end of the latch case 48 comes into contact with a locking plate 49 provided in the control rod handling bed 30, the extension tube stops descending.

The link type latch finger 41 which has been expanded by the above operation attracts the armature 1143 by passing current through the magnet 42, thereby maintaining the expanded state.

To pull out the control rod 29, the inner and outer extension tubes 22.15 are raised simultaneously in the above-described state, so that the locking piece 41a of the link type latch finger 41 and the locking piece 30a of the control handling head 30 come into contact with each other, and the control rod 29 is pulled out. 911 tribute 29 will be handled.

If the reactor requires an emergency scram for some reason, the magnet 42 is energized and disconnected for 15 minutes to remove the adhesion to the armature 43, and the armature 1t 43 is attached to the support plate. The link type latch finger closes as it falls down to 47, so the latch tj
The l lfJ 40 and the control rod 29 are disengaged, and the two control rods inevitably fall.

The position of the control rod 29 at this time is such that it can be used at any time by the center 45 and the magnet 46.

[Effects of the invention] As explained below, by using a link-type latch finger and storing it in a latch case, the control rod can be easily bent due to heat bending, etc. If the latch mechanism is inserted eccentrically, the side of the finger may come into contact with the inner surface of the control rod handling head, creating an excessively thick friction force, or the finger may come into contact with the top of the control rod handling head for some reason and buckle. There are no major malfunctions, and since the evaporator is immersed in sodium, the conventionally used latch bellows are unnecessary, and there are no problems with sealing inside and outside the furnace. Furthermore, because the position detector is installed at the lower end of the latch case, there is a type 6 that cannot track the position of the control rod until it is fully inserted, making it uncertain whether the control rod has reached the lower end. However, this method solves this problem.

As mentioned above, the present invention has a control rod 29 attached to the lower ends of the inner and outer extension tubes 22.15, and a magnet 42 for detecting the position of the falling force. and armature 43, a latch mechanism 40 consisting of a link type latch finger 41, a latch case 48, and an operating rod 44, a position detector consisting of a center 45, and magnets i~4G. By doing so, it is possible to reduce various factors that have been problems in the past, and to further improve IG operation reliability, thereby providing a control rod drive device that can further improve the safety of C nuclear reactors.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view of a conventional control rod drive device, and FIG. 2 is a J-longitudinal sectional view showing an embodiment of a control rod drive device 6 according to the present invention. 15・・・・・・・・・Outer extension・22・・・
......Inner extension tube 29...
... Control rod 30 ... Control rod handling head 40 ... Latch mechanism 41 ...
......Link type latch finger 42...
・・・・・・・・・Magnet 1-43・・・・・・・
・・・・・・Armach 1?44・・・・・・・・・・・・
Operation rod 45...............
-46・・・・・・・・・Magnet 47...
......Support plate 48...Latch case 49...
...... Patent attorney representing the locking board Noriyuki Chika 14. i (and 1 other person) Figure 1 Figure 2

Claims (2)

[Claims] (1) Reactor output adjustment a3 J: In a control rod drive device that has a latch mechanism for vertically moving or disconnecting the control rods in the event of an emergency shutdown, the control rods are attached 1]1. ! The latch finger for latch is a link type, and a magnet 1 and an armage 1 are attached to the upper part of the latch finger in order to attach the control rod to the skin by this link type latch finger.
2. A control rod drive device characterized in that: an operating rod is provided on the lower surface of the armature for opening and opening the link type latch fingers. (2) The control rod drive device according to claim 1, further comprising a control rod position detection coil at the lower end of the latch mechanism and a permanent magnet inside the control rod.