KR20030082210A - Ballscrew type Control Element Drive Mechanism with Quick Insertion System and Manual Drive - Google Patents

Abstract

PURPOSE: A ball screw-type apparatus for driving a control rod having an emergency inserting device and a manual driving device is provided to improve the emergency inserting ability by using the emergency inserting device and a canceling spring. CONSTITUTION: An ultrasonic sensor(22) is installed on a lower end of a step motor(17) to detect a rotation thereof. A ball screw assembly(6) installed within a low pressure vessel(34) is connected to the step motor(17) and comprised of a screw(7), a spline(10), a ball nut(8), a ball bearing(9), a guidance shaft(12), and a guiding bearing(11). A manual driving device is connected to a bevel gear rotatory shaft(45) connected to a bevel gear(35) and inserts forcibly a control rod by a worker in case of emergency. An emergency inserting device(A) is installed on the low pressure vessel(34) and the ball screw assembly(6) and drops vertically and emergently the ball screw assembly(6) without rotating of the ball nut(8) where a scram signal turns on. A buffering device is comprised of an upper buffering device(32) for wrapping the guidance shaft(12) and a lower buffering device(33) installed on a lower portion of the spline. A plurality of position pointers(25) is installed on an outside of an upper pressure vessel(24) by a position pointer holder(27) to output an analog stage voltage signal by a permanent magnet(26) installed on an upper end of the guidance shaft(12). An exhauster(47) is installed on each upper portion of the upper pressure vessel(24) and the step motor(17) to eliminate air.

Description

Ballscrew type control element drive mechanism with quick insertion system and manual drive

The present invention relates to a control rod driving device using an emergency insertion device and a manual driving device. More specifically, the reactor is heated using nuclear fission reaction heat at the start of the reactor, and in the integrated reactor which does not use boric acid to control the reactivity during operation. The emergency rod insertion device and release spring are used as the control rod driving device for responsiveness control, and the emergency insertion ability is excellent, and the manual driving device is equipped with the control rod drive that can be manually inserted externally when an abnormal condition occurs inside the control rod driving device. Relates to a device.

Currently, six PWRs of the Westinghouse, two PWRs of Pramatom, and four PWRs of ABB-CE of the United States are operating as power generation reactors in Korea, and four CANDU reactors of Canada are also in operation. The research reactor is currently in operation at Hanaro, which was built at General Atomic's TRIGA reactor and the Korea Atomic Energy Research Institute. The control rod driving devices used in these reactors have different structures and driving principles for each reactor type, and since they are all introduced from abroad, there are no domestic developments. Pneumatic piston and motor driven lead screw method and rack and pinion in research reactors of TRIGA Mark-II which started in March 1962 and TRIGA Mark-III which started in April 1972 Control rod drive system was used. Pressurized water-type reactors, which have been introduced since 1974, are equipped with magnetic jack-type control rod drives, and CANDU reactors are wire drum-driven. Therefore, the ball screw type control rod drive device as in the present invention has never been used.

In foreign countries, the control rod drive began to be used in December 1942, when the first reactor was operated in the United States by Enrico Fermi. Early control rod drive devices are mainly applied to pneumatic driving method, and there is a problem in reliability of piston part. Since the early 1950s, it has been developed as a wire drum method using gears. come. The boilers in which the ball screw type driving device is used include Shippingport PWR, Hallam, Enrico- Fermi, Peach Bottom and NRU, but the ball screw type which improves the emergency insertion performance by using the emergency insertion device or the manual driving device as in the present invention. Control rod drive device is not found yet.

The present invention is devised to solve the conventional problems as described above, the object of which is to adjust the movement distance of the screw per step of the step motor within 0.5mm as well as emergency by adopting the ball screw type By adopting the insertion device and the release spring, it is possible to insert the control rod quickly in case of emergency.In addition, when the manual rod is adopted, it is difficult to insert the control rod only by the step motor due to the abnormal state inside the control rod driving device. The present invention provides a ball screw type control rod driving device capable of inserting a control rod.

The present invention for achieving the above object is the rotational motion of the rotary step motor is transmitted to the ball nut through the bevel gear and the rotational motion of the ball nut is converted into a linear motion of the screw to drive the control rod connected to the screw up and down Fine adjustment within 0.5mm is possible, and in order to emergency control the core in case of emergency, the moving anchor attached to the fixed anchor by the force of the electromagnet releases the excitation of the electromagnet to freely drop the core to the distance to emergency control. It is configured to lower the control rod attached to it.

1 is a functional explanatory diagram of a control rod drive device

2 is a cross-sectional view of the control rod drive device of the present invention

Figure 3 is a detailed view of the step motor and manual drive device of the present invention

Figure 4 is a detailed view of the ball screw assembly and the emergency insertion apparatus of the present invention

Figure 5 is a detailed view of the upper pressure vessel of the present invention

Figure 6 is a detailed view of the release spring and connecting rod assembly of the present invention

7 is a plan view of the control rod drive device of the present invention

8 is an embodiment of a control rod drive device in the present invention

<Description of Symbols for Main Parts of Drawings>

(A): Emergency insertion device (B): Manual drive device

(N): Ball nut assembly (1): Control rod drive device

(2): extension rod (3): reactor

(4): control rod (5): core

(6): ball screw assembly (7): screw

(8): Ball nut (9): Ball bearing

(10): spline (11): guide bearing

(12): guide shaft (13): hinge joint

(14): Bearing guide (15): Bayonet connecting device

(16): Foreign material blocking bearing (17): Step motor

18: external stator teeth 19: external stator

20: internal stator 21: rotor

22: ultrasonic sensor 23: ultrasonic sensor object

(24): Upper pressure vessel (25): Position indicator

(26): permanent magnet (27): position indicator holder

(28): fixed anchor (29): moving anchor

(30): Winding Block

(31): Upper and lower limit switch for emergency insertion device

(32): upper shock absorber (33): lower shock absorber

(34): Lower pressure vessel (35): Bevel gear

(36) (36a) (36b) (36c): release spring

(37) (37a) (37b): release spring guide

(38): connecting rod assembly (39): fastening rod

40: fastening spring 41: stop jaw

(42): Manual drive container (43): Upper nut

(44): Manual drive shaft (45): Bevel gear rotating shaft

(46): thrust bearing (47): exhaust system

(48): pressurizer cover (49): copper gasket

(50): cooler (51): support structure

(52): Stud bolt

Referring to the configuration of the present invention in conjunction with the accompanying drawings as follows.

1 shows a functional explanatory diagram of a control rod driving apparatus, in which a control rod driving apparatus 1 is usually installed on an upper portion of the reactor 3 and extends with a control rod 4 for controlling the core 5 of the reactor 3. A device connected through the rod (2), which controls the nuclear reactivity of the core (5) by adjusting the insertion amount of the control rod (4) during the normal operation of the reactor (3), and also causes an accident in the reactor system When the urgent output stop is required, the control rod 4 is inserted into the core 5 quickly and accurately to stop the nuclear reactivity.

Figure 2 is a cross-sectional view of the control rod drive device of the present invention, Figure 3 is a detailed view of the step motor and manual drive device of the present invention, Figure 4 is a detailed view of the ball screw assembly and the emergency insertion device of the present invention, Figure 5 Is a plan view of the control rod drive device of the present invention, the control rod drive device of the present invention is largely a rotary step motor 17, ball screw assembly (6), manual drive device (B), emergency insertion device (A) , Release spring 36, shock absorber, position indicator 25, exhaust device 47.

The rotary step motor 17 is a four-phase variable reluctance stepping motor, which does not require self-sealing and is a sealed motor. The step motor 17 has an external stator tooth 18 made of a part of the container inside the sealed container and the container, an external stator 19 composed of independent four-phase windings, an internal stator 20 installed at the center of the container, and the external stator. It consists of the rotor 21 provided between 19 and the internal stator 20. As shown in FIG. The external stator 19 is a form in which the external stator teeth 18 are wound, and the stator and the rotor teeth are composed of 12 pieces. In addition, since the external stator 19 is all installed outside the external stator teeth 18, the first order does not directly reach, and the space with the external stator is covered with a thin stainless steel container and sealed again.

The external stator tooth 18, which also acts as a pressure vessel, is unipole by welding a nonmagnetic welding material between each winding to facilitate the formation of a magnetic field, that is, by welding a nonmagnetic ring between several annular magnetic rings. To form a magnetic field. The rotor and stator teeth have a multi-stage structure consisting of four phases, each of which has two equivalent stages, and all phases have the same pitch, but each phase of the rotor 21 has a 7.5 ° phase angle with the adjacent phase. Therefore, the rotation angle of the rotor 21 per pulse of the step motor 17 is 7.5 degrees. The rotor 21 is cylindrical and welded alternately with a nonmagnetic material and a magnetic material. The step motor 17 is a two-excitation method driven by alternately exciting two adjacent windings among four windings in the vertical direction.

In the lower part of the step motor 17, an ultrasonic sensor 22 capable of detecting one step rotation of the step motor 17 is installed, and the object 23 of the ultrasonic sensor 22 is composed of 24 teeth. It is configured to detect the rotation of each step of the step motor 17.

The rotational force of the step motor 17 is transmitted to the ball screw assembly 6 through the bevel gear 35 installed at the bottom of the step motor 17.

The step motor 17 may also use a permanent magnet type step motor that inserts a permanent magnet inside the internal stator 20, in which case it is possible to greatly increase the thrust of the step motor.

The ball screw assembly 6 is connected to the step motor 17 and is installed in the lower pressure vessel 34 installed at the upper end of the cooler 50, and the screw 7 is connected by the connecting rod and the connecting rod assembly 38. ), A spline 10 which receives the rotational force from the bevel gear 35 connected to the step motor 17 and frees the vertical movement of the screw 7, and is connected to the upper end of the spline 10 and the screw 7. ) Is installed in the ball nut 8 for raising and lowering the ball nut, the ball bearing 9 installed at the upper end of the ball nut 8, and the upper pressure vessel 24 installed at the upper end of the lower pressure container 34. It consists of a guide shaft 12 connected to the upper end of the screw 7 by a hinge joint 13, and a guide bearing 11 connected to the guide shaft 12.

In order to prevent foreign matter from entering the inside of the ball nut 8, the foreign matter blocking bearing 16 is installed above and below the ball nut 8, and one side of the foreign matter blocking bearing 16. The face was installed to snap into the groove of the screw (7).

The guide shaft 12 is installed to prevent the bending load due to the installation error of the upper pressure vessel 24 installed on the upper end of the screw 7 to the screw 7 directly. 12) is connected to the guide bearing 11 for preventing the rotation of the screw (7) and reducing the frictional resistance during shanghai, grooves are formed on both sides of the upper pressure vessel (24) It moves up and down along the bearing guide 14.

The connecting rod assembly 38 is installed at the lower end of the cooler 50, and the bayonet connecting device (15, 15 ') on the upper and lower portions to facilitate the connection and release of the screw (7) and the extension rod (2) ) Is installed, the fastening bar 39 is installed inside the connecting rod assembly 38, and a fastening spring 40 for aligning the fastening bar 39 in place is installed at the bottom thereof.

As such, when the reactor vessel center cover is removed or the reactor vessel center cover is installed in the boiler by the bayonet connection structure, only the control rod driving device can be removed or installed.

In addition, outside the connecting rod assembly 38, when the control rod is excessively raised beyond the prescribed stroke due to the abnormality of the step motor control system, a stop jaw 41 is formed to block the damage and prevent the damage of the control rod driving device. .

The manual driving device (B) is forcibly inserting the control rod by the operator when driving to the step motor 17 alone is not possible due to an unexpected failure in the control rod driving device, and is connected to the lower end of the step motor 17. The manual drive device container 42 installed on one side of the lower pressure container 34 and the inside of the manual drive device container 42 are supported by the thrust bearing 46 and connected to the bevel gear 35 when reversing. It consists of a manual drive shaft 44 connected to the bevel gear rotation shaft 45 and an upper nut 43 installed at the end of the manual drive device container 42, the manual drive shaft 44 is a bevel gear rotation shaft in normal operation If it is separated from (45) but needs manual driving, loosen the upper nut (43) installed in the manual driving device, the manual driving shaft (44) is pulled outward by the internal pressure and coupled to the bevel gear rotating shaft (45). To enable it to be rotated by the force.

The emergency insertion device (A) is to vertically lower the ball screw assembly (6) by a predetermined distance without the rotation of the ball nut (8) when the scram signal is received, the fixed anchor fixed inside the lower pressure vessel (34) (28), the lower pressure vessel to be located at the upper end of the ball nut (8) connected to the ball bearing (9), and the outer side of the fixed anchor (28) and the moving anchor (29) Winding block 30 installed in (34), and the upper and lower limit switch 33 for the emergency insertion device installed in a predetermined position outside the lower pressure vessel 34 to detect whether the control rod is completely pulled out / inserted. .

In addition, a portion of the lower pressure vessel 34 in which the fixed anchor 28 and the moving anchor 29 are installed was formed by welding a portion of the magnetic ring to form a smooth magnetic field.

The vertical falling distance of the ball screw assembly 6 is determined as the distance that can initially control the core through the core analysis.

The winding block 30 is composed of two sets in preparation for the failure of one winding block 30.

When the starting force of the step motor 17 is transmitted to the ball nut assembly N composed of the spline 10-the ball nut 8-the ball bearing 9 through the bevel gear 35 at the initial startup, the ball nut assembly N ) And ascend by the designed distance, the moving anchor 29 installed on the upper end of the ball nut assembly N is attached to the fixed anchor 28 by the force of the electromagnet, and then the rotation of the step motor 17 The motion is changed to the vertical motion of the screw 7. This is because the ball nut assembly N is rotated along the groove of the screw 7 by the screw 7 whose rotation is constrained by the guide bearing 11, and then the fixed nut 28 and the moving anchor 29 rise. At the same time, the movement of the ball nut 8 is constrained so that the screw 7 moves up and down by the rotational movement of the ball nut 8. However, at the time of scrambling, the ball screw assembly 6 suspended only by the force of the electromagnet composed of the fixed anchor 28 and the moving anchor 29 by cutting off the power of the electromagnet is designed without the rotation of the ball nut 8 by the weight of the movable part. It will descend vertically by the distance to control the core.

The release springs (36) (36a) (36b) (36c) are to be inserted into the core at the time of scrambling control rod rapidly, but the weight of the moving part alone can not lower the screw (7) at high speed, so that it is reinforced To insert the control rod quickly, it is installed at the bottom of the cooler 50 installed in the lower portion of the lower pressure vessel 34, consists of two different springs that twist upwards, to minimize the twisting of the release spring during compression In order to separate the four springs in the vertical direction.

In addition, release spring guides 37, 37a and 37b which can be freely moved between each spring in the up and down direction to freely move the spring end when the release springs 36, 36a, 36b and 36c are compressed. ) Is installed.

The release spring may be installed inside the upper pressure vessel 24, but at this time, the overall length of the control rod driving device is increased, thereby making it vulnerable to dynamic load.

When the power supply of the emergency insertion device (A) electromagnet at the time of scrambling, all moving parts including the screw (7) are rapidly lowered by a certain distance by the force of the self-weight and the release spring, the impact generated at this time In order to prevent damage to the control rod drive device by the upper shock absorber 32 and the lower shock absorber 33 was configured.

The upper buffer device 32 is composed of a hydraulic damper and the inner and outer springs are installed to surround the guide shaft 12 on the fixed anchor 28, the inner and outer springs are fully compressed even when considering the free fall load of the movable part The maximum stroke of the inner and outer springs should be determined so that the screw (7) and the extension rod (2) can be connected when the control rod drive device is fastened, and the container enclosing the spring moves up and down during the initial tightening. Friction bearings are installed on the friction surface to reduce friction with the inner surface of the pressure vessel.

The lower shock absorber 33 is composed of a spring is installed on the bottom of the spline 10 drop stroke, the same as the upper shock absorber 32, the container surrounding the spring to reduce the friction when moving up and down on the friction surface Install friction bearings.

The position indicators 25 are independently provided with four position indicators 25 using a reed switch outside the upper pressure vessel 24. In addition, a permanent magnet 26 is installed on the guide shaft 12 of the ball screw assembly 6 to move up and down together with the screw 7, and is installed on the outer wall of the pressure vessel in proportion to the position of the permanent magnet 26. The position indicator 25 is configured to output a stepped analog voltage signal.

During operation, two or three reed switches in the position indicator 25 are always closed, and the position indicator 25 is connected by a voltage divider circuit connected to the reed switch and a resistor so that a voltage signal corresponding to the closing of each reed switch is received. The four position indicators 25 are output to each of the two position indicator holders 27 made of aluminum, and the position indicator holders 27 surround the outer wall of the upper pressure vessel 24. It is installed in the form.

Two of the four position indicators 25 are provided with a non-safety upper limit switch (not shown) and a lower limit switch (not shown) that can indicate the upper and lower limits of the control rod. In addition, when the power supply of the step motor 17 is cut off and the control rod is at the lowest position by the weight of the movable part, a control rod drop switch (not shown) which can detect this is installed.

The exhaust device 47 is installed on the upper pressure vessel 24 and the step motor 17, respectively, to remove the air that collects on the control rod driving device when the coolant is filled before starting the reactor.

The control rod driving device configured as described above is installed in the reactor head as shown in FIG. 6, in the case of an integrated reactor, a pressurizer is generally installed in the upper part of the reactor, and the pressurizer cover 48 serves as the reactor head.

Therefore, it is possible to install the release spring 36 and the connecting rod assembly 38 in the pressurizer.

The control rod drive device is an annular copper gasket 49 which is fixed with four stud bolts 52 and nuts on the cooler 50 and has a rectangular cross section for sealing.

Since the material used for the ball bearing 9 or the ball screw 7 is generally vulnerable to high temperature, the cooler 50 is first installed when installing the reactor head in order to prevent the high temperature coolant from flowing into the control rod driving device. It is welded to the reactor head, and a control rod driving device is installed thereon.

In addition, the support structure 51 may be provided to improve the resistance of the upper structure to the dynamic load.

Further, by adjusting the number of teeth of the step motor 17, the lead pitch of the screw 7, the reduction ratio of the reduction gear, etc., the movement distance of the control rod per step of the step motor 17 can be adjusted.

In addition, the emergency insertion device can be removed and used as a control rod drive device exclusively for core adjustment, but the control rod drive device for reactor emergency stop must be used in parallel.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

As described above, the present invention not only finely adjusts the control rod to within 0.5 mm, but also solves the emergency insertion ability, which is the biggest vulnerability of the ball screw type control rod driving device, by using the emergency insertion device and the release spring, thereby causing an accident in the reactor system. When the urgent output stop is required, the control rod can be inserted into the core quickly and accurately to stop the nuclear reactivity, thus preventing safety accidents, the control rod fine adjustment performance, and the ship's integrated type that delivers a large dynamic load. There is an effect that can be installed in the reactor.

Claims (6)

A rotary step motor 17, An ultrasonic sensor 22 installed at a lower end of the step motor 17 to detect rotation of the step motor 17; Screw 7 is connected to the step motor 17 and is installed in the lower pressure vessel 34 installed on the upper end of the cooler 50, and is connected by a connecting rod and a connecting rod assembly 38, and the step motor 17. Spline 10 for receiving the rotational force from the bevel gear 35 connected to the) and freely moving the screw 7 in the vertical direction, and a ball nut connected to the upper end of the spline 10 to raise and lower the screw 7. (8), the ball bearing (9) installed on the upper end of the ball nut (8), and the upper pressure vessel (24) installed on the lower pressure vessel (34) is located inside the hinge of the screw (7) A guide shaft 12 connected by the joint 13 and a guide bearing 11 connected to the guide shaft 12 to move up and down along the bearing guide 14 installed inside the upper pressure vessel 24. Ball screw assembly (6), A manual driving device connected to the bevel gear rotating shaft 45 connected to the bevel gear 35 in an emergency and forcibly inserting a control rod by an operator; An emergency insertion device (A) installed in the lower pressure vessel (34) and the ball screw assembly (6) to urgently lower the ball screw assembly (6) by a predetermined distance without a rotation of the ball nut (8) when a scram signal is input (A). )Wow, The upper shock absorbing device 32 is installed to surround the guide shaft 12 and composed of a hydraulic damper and the inner and outer springs, and the shock absorber consisting of a lower shock absorber 33 formed of a spring and installed below the drop stroke of the spline 10. Device, A plurality of position indicators 25 installed by the position holder 27 on the outside of the upper pressure vessel 24 and outputting a stepped analog voltage signal by the permanent magnet 26 installed on the top of the guide shaft 12. Wow, Emergency insertion device, characterized in that the upper pressure vessel 24 and the step motor 17, respectively installed in the upper portion of the exhaust device 47 for removing the air collected in the upper control rod drive device when the coolant is filled before the start of the reactor start Ball screw type control rod drive device with a drive and manual drive. The method of claim 1, The emergency insertion device is located at the upper end of the screw (7) and the fixed anchor 28 fixed inside the lower pressure vessel (34), and the ball nut (9) located at the upper end of the ball nut (8) (8) the moving anchor 29, the fixed block 28 and the winding block 30 provided in the lower pressure vessel (34) to be located outside the moving anchor 29, the complete withdrawal / insertion of the control rod Ball screw type control rod driving device having a gib insertion device and a manual device, characterized in that consisting of upper and lower limit switches 33 installed at a predetermined position outside the lower pressure vessel (34) to detect whether or not. The method of claim 1, The release springs 36, 36a, 36b, and 36c which are installed at the lower end of the cooler 50 and composed of two different springs which are twisted up and down, are separated into four springs in the vertical direction, and the Ball screw type with emergency insertion device and manual drive device, characterized in that it comprises a release spring guides 37, 37a, 37b installed between the release springs 36, 36a, 36b, 36c. Control rod drive system. The method of claim 1, The step motor 17 is composed of an outer stator tooth 18 made of a part of a container and a sealed container and a container, and an independent stator 19 wound around the outer stator tooth 18, which is formed at an independent center of the container. Ball screw type control rod drive device having an emergency insertion device and a manual drive device, characterized in that the rotor (21) installed between the internal stator (20), the external stator (19) and the internal stator (20). The method of claim 1, The manual drive device is a manual drive device container 42 installed on one side of the lower pressure vessel 34, and is located inside the manual drive device container 42 is supported by the thrust bearing 46 and bevel gears when reversing Emergency insertion device and manual drive, characterized in that consisting of a manual drive shaft 44 connected to the bevel gear rotating shaft 45 connected to 35, and an upper nut 43 installed at the end of the manual drive device container 42 Ball screw type control rod drive device with device. The method of claim 1, The connecting rod assembly 38 has a bayonet connection device (15, 15 ') is installed in the upper and lower, the fastening rod (39) is installed inside, the fastening rod (39) at the bottom of the fastening rod (39) Fastening spring 40 is installed to align the position of the emergency insertion device and manual, characterized in that the stop jaw 41 to prevent excessive rise of the control rod is formed in a predetermined position outside the connecting rod assembly 38 Ball screw type control rod drive device with drive system.