JP6684689B2 - Control rod drive mechanism position indicator - Google Patents

Description

  Embodiments of the present invention relate to a position indicating device for a control rod drive mechanism used in a boiling water reactor.

  FIG. 5 shows a vertical sectional view of a conventional boiling water reactor (hereinafter referred to as BWR). A reactor pressure vessel (hereinafter referred to as RPV) 1 contains cooling water 2 which also serves as a moderator, while a central core 3 is arranged in the lower central portion, and the core 3 is surrounded by a core shroud 4. A large number of fuel assemblies (not shown) are loaded in the core 3, and control rods 5 are housed so as to be freely inserted and removed between the four fuel assemblies.

  In this BWR, the cooling water 2 flows upward in the core 3, while the heat generated by the nuclear fission chain reaction from the core 3 is transferred to the cooling water 2, and the cooling water 2 is heated. The heated cooling water 2 becomes a gas-liquid two-phase flow of water and steam, flows above the core 3, and is guided from the core 3 to the steam separator 6.

  After the gas-liquid two-phase cooling water 2 is separated into water and steam by the steam separator 6, the steam is sent from the main steam pipe to the steam turbine system through the steam dryer (not shown) to pass through the steam turbine. Drive it. The steam that has worked in the steam turbine system is condensed in the condenser to become condensed water, and then returns to the RPV 1 as supply water through the reactor condensate system and the supply water system.

  On the other hand, the water separated by the steam separator 6 flows down the downcomer unit 7 and is guided to the lower part of the core in a state of being mixed with the feedwater sent through the reactor condensate system and the feedwater system, and again the core 3 Be led to.

  A control rod drive mechanism (hereinafter referred to as CRD) 8 is used to move the control rod 5 into and out of the core 3 of the RPV 1 for starting and stopping the reactor and adjusting the reactor output. The CRD 8 is a structure (assembly) housed in a control rod drive mechanism housing (hereinafter referred to as CRD housing) 9 that extends through the bottom portion 1a of the RPV 1, and is fixed to the lower flange 9a of the CRD housing 9 by bolting. It

  FIG. 6 shows an electric drive type CRD 8 in which an electric motor 10 is attached to the lower part. A rotating shaft 11 from the electric motor 10 is connected to a drive shaft 13 of the CRD 8 via a gear coupling mechanism 12. The drive shaft 13 is rotatably connected to a ball screw shaft 14, and a ball nut 15 is screwed onto the ball screw shaft 14.

  A pair of rollers 16 is installed on the ball nut 15 so as to sandwich an axial mounting plate 18 formed on the inner peripheral surface of the guide tube 17. A drive piston 19a is installed above the ball nut 15, and the drive piston 19a is connected to the control rod 5 via a coupling 20 installed at the upper end of the hollow piston 19. The ball screw shaft 14 is rotated by the drive of the electric motor 10 via the rotary shaft 11 and the drive shaft 13, and the ball nut 15 is vertically moved by the rotation of the ball screw shaft 14. At that time, the rotation of the ball nut 15 is restricted by the mounting plate 18 and the ball nut 15 moves up and down, and the vertical movement of the ball nut 15 causes the control rod 5 to move up and down via the hollow piston 19.

  By the vertical movement of the control rod 5, the amount of insertion and withdrawal into and from the reactor core 3 is adjusted to control the reactor output. Reference numeral 21 is an electromagnetic brake, reference numeral 22 is a synchro position detector, reference numeral 23 is a motor bracket, and reference numeral 30 is a spool piece.

  When an emergency occurs in the BWR and the reactor is to be scrammed (emergency stop), the scram insertion pipe 25 connected to the lower flange 9a of the CRD housing 9 is connected to the drive piston 19a via the scrum water inlet (water injection port) 26. High-pressure drive water is supplied to the lower surface side. The hollow piston 19 installed on the ball nut 15 is pushed upward by the supply of the high-pressure driving water, and the control rod 5 is inserted into the core 3 at high speed to achieve the function.

  In order to know the insertion amount of the control rod 5 at the time of scram operation, the magnet 32 is attached to the drive piston 19a, and the proximity sensor 37 shown in FIG. (Hereinafter referred to as PIP) 35 is provided, and the movement speed of the magnet 32 and the movement speed of the control rod 5 are detected by detecting the movement of the magnet 32 according to the movement of the hollow piston 19 based on the opening / closing state of the reed switch 39 in the proximity sensor 37. It is configured to detect.

  Further, the CRD 8 is provided with a separation detection probe (hereinafter referred to as SIP) 36 that detects the separated state when the control rod 5 is sticked (fixed) in the core 3 and the hollow piston 19 is separated from the ball nut 15. In the SIP 36, since the weight of the control rod 5 is unloaded from the driving part when the hollow piston 19 is separated, the separation magnet 33 is lifted by the force of the spring 34, and the movement of the separation magnet 33 at this time is shown in FIG. It is detected by the open / closed state of the reed switch 39 in 38.

JP, 7-1559577, A JP-A-3-225202

  PIPs and SIPs, which are conventional control rod drive mechanism position indicating devices, use a proximity sensor in which a reed switch for position detection is mounted on a frame of a fixed shape and then molded (fixed) with resin. In this case, the operating range of the proximity sensor is determined only by the operating characteristics of the attached reed switch and cannot be adjusted. In addition, the yield of reed switches satisfying the operation characteristics required for the proximity sensor is poor in some cases due to the operation characteristics of the reed switch alone.

  For example, in SIP, the distance from the ON point to the center of the sensor and the distance from the center of the sensor to the OFF point are specified, but the relationship between the ON point distance and the OFF point distance of the reed switch is almost fixed, and the above-mentioned requirements are satisfied. This is because there are few reed switches to operate. Therefore, those which do not satisfy the operation range required for the inspection after the completion of the proximity sensor have been discarded.

  In PIP, the reed switch operation width may be shorter or longer than the required operation width regulation.

  In the present invention, the operation position and the operation width of the reed switch can be adjusted even after the completion by combining a plurality of reed switches, and the yield of the structure having the structure in which the operation range of the proximity sensor can be adjusted by these adjustments An object is to obtain a control rod drive mechanism position pointing device having a high proximity sensor.

The present invention is a control rod for detecting the position or state of a control rod drive mechanism for controlling the output of a nuclear reactor from the ON point and the OFF point of a reed switch that is opened and closed by magnetic force of a magnet arranged in the control rod drive mechanism. a drive mechanism pointing device, wherein the reed switch is individually reed switch for detecting the reed switch and the OFF point for detecting the ON point of the operating position and adjustably installed independently position, the operating position The reed switch for detecting the ON point and the reed switch for detecting the OFF point are arranged so as to be shifted in parallel and have different operation regions .

  In the embodiment of the present invention, the operation position and the operation width of the reed switch can be easily adjusted by combining a plurality of reed switches.

FIG. 3 is an explanatory diagram showing a configuration of a proximity sensor for a separation detection probe (SIP) showing Example 1 of the present invention. FIG. 6 is an explanatory diagram showing the configuration of a proximity sensor for a scrum position detection probe (PIP) showing a second embodiment of the present invention. FIG. 7 is an explanatory diagram showing the configuration of a proximity sensor for a scrum position detection probe (PIP) showing a third embodiment of the present invention. FIG. 7 is an explanatory diagram showing the configuration of a proximity sensor for a scrum position detection probe (PIP) showing a third embodiment of the present invention. FIG. 6 is a vertical cross-sectional view showing a conventional example of a boiling water reactor. FIG. 6 is a vertical sectional view of the control rod drive mechanism shown in FIG. 5. The installation state of a scrum position detection probe is shown, (a) is a partial cutaway side view, (b) is an AA sectional view of (a). The installation state of a separation detection probe is shown, (a) is a partial cutaway side view, (b) is a BB sectional view of (a).

  An embodiment of a control rod drive mechanism position pointing device according to the present invention will be described below with reference to the drawings.

(Example 1)
Hereinafter, Embodiment 1 will be described with reference to FIG. In the first embodiment, the same parts as those in FIGS. 5 to 8 are designated by the same reference numerals, and the description of the configuration will be omitted.

  FIG. 1 is an explanatory diagram showing a configuration of a proximity sensor 40 for a separation detection probe (SIP). The specifications required for the proximity sensor 40 for SIP are an ON point position when the separation magnet 33 moves from the left side in FIG. 1 and an OFF point position when the separation magnet 33 moves from the right side in FIG. A reed switch A41 and a reed switch B42 having different operation regions are arranged on the board so as to be shifted in parallel (the operation region of the reed switch A41 <the operation region of the reed switch B42) and connected in parallel.

  When the separating magnet 33 moves from the left side of FIG. 1 in the magnet moving direction C, the operation area of the reed switch A41 becomes the operation area 51, and the operation area of the reed switch B42 becomes the operation area 52, and the operation area 51 is turned ON. The point becomes the ON point 53 of the SIP proximity sensor 40.

  When the separating magnet 33 moves from the right side of FIG. 1 in the magnet moving direction D, the operation area of the reed switch A41 becomes the operation area 54, the operation area of the reed switch B42 becomes the operation area 55, and the operation area of the reed switch B42 becomes. The OFF point becomes the OFF point 56 of the SIP proximity sensor 40.

  The position of each reed switch A41 and reed switch B42 can be adjusted. In this configuration, the ON point and the OFF point are assigned to the independent reed switch A41 and reed switch B42, respectively, and adjustment is easy.

  The amount of shift between the reed switch A41 and the reed switch B42 can be set in consideration of the difference in the distance between the ON point and the OFF point from the center of the reed switch.

  Therefore, since the reed switch A41 and the reed switch B42 can be set according to the specified value of the operation width required by the SIP proximity sensor 40, the movement of the separation magnet 33 can be reliably detected, and the proximity with high yield can be achieved. A control rod drive mechanism position indicating device having a sensor can be obtained.

(Example 2)
The second embodiment will be described below with reference to FIG. In the second embodiment, the same parts as those in FIGS. 1 and 5 to 8 are designated by the same reference numerals, and the description of the configuration will be omitted.

  FIG. 2 shows the configuration of the proximity sensor 43 for the scrum position detection probe (PIP). Two reed switches A44 and reed switch B45 are arranged on the board so as to be shifted in parallel and connected in parallel.

  The proximity sensor 43 for PIP has an operation width of the combined operation area 57. When the separating magnet 33 moves from the left side of FIG. 2 in the magnet moving direction C, the ON operation range 51 and 52 of the reed switch A44 and the reed switch B45 are combined to be the ON operation range as the PIP proximity sensor 43. Become.

  The positions of the respective reed switches A44 and B45 can be adjusted, and the positions of the ON point and the OFF point can be easily adjusted. Further, the operation width can be adjusted by changing the shift amount of the reed switch A44 and the reed switch B45, and it is possible to cope with the case where the operation width wider than the operation width of the reed switch alone is required.

  Therefore, since the reed switch A44 and the reed switch B45 can be set according to the specified value of the operation width required by the PIP proximity sensor 43, the movement of the magnet 32 can be reliably detected, and the proximity sensor with high yield can be obtained. A control rod drive mechanism position pointing device having

(Example 3)
Example 3 will be described with reference to FIG. In the third embodiment, the same parts as those in FIGS. 2 and 5 to 8 are designated by the same reference numerals, and the description of the configuration will be omitted.

  FIG. 3 shows the configuration of the proximity sensor 46 for the scrum position detection probe (PIP). Two reed switches A44 and reed switch B45 are arranged in parallel with each other on the board so as to be shifted in parallel, and are connected in series. The PIP proximity sensor 46 has an operation width of the combined operation area 58. In the range where the reed switch A44 is ON and the reed switch B45 is ON, that is, when the magnet 32 moves in the magnet moving direction C from the left side of FIG. 3, the reed switch A44 moves from the ON point of the reed switch B45. Up to the OFF point is the operating range of the PIP proximity sensor.

  The positions of the respective reed switches A44 and B45 can be adjusted, and the positions of the ON point and the OFF point can be easily adjusted. Further, the operation width can be adjusted by changing the shift amount of the reed switch A44 and the reed switch B45, and it is possible to cope with the case where the operation width narrower than the operation width of the reed switch alone is required.

  Therefore, since the reed switch A44 and the reed switch B45 can be set according to the specified value of the operation width required by the PIP proximity sensor 46, the movement of the magnet 32 can be reliably detected, and the proximity sensor with high yield can be obtained. A control rod drive mechanism position pointing device having

(Example 4)
Example 4 will be described with reference to FIG. In the fourth embodiment, the same parts as those in FIGS. 3 and 5 to 8 are designated by the same reference numerals, and the description of the configuration will be omitted.

  FIG. 4 shows the configuration of the proximity sensor 47 for the scrum position detection probe (PIP). Two reed switches A44 and reed switches B48 are arranged on the board in parallel and offset from each other, and are connected in series. The reed switch A44 is a reed switch (normally open type) shown in an operation region 51 which is turned on by the magnetic force of the magnet, and the reed switch B48 is a reed switch (normally closed type) shown in an operation region 59 which is turned off by the magnetic force of the magnet. When the separating magnet 33 moves from the left side of FIG. 4 in the magnet moving direction C, the combined operation area 60 of the operation area 51 of the reed switch A44 and the operation area 59 of the reed switch B48 is the operation width of the PIP proximity sensor 47. Becomes The range from the ON point 61 of the reed switch A44 to the OFF point 62 of the reed switch B48 is the operating range of the proximity sensor for PIP.

  The positions of the respective reed switches A44 and B48 can be adjusted, and the positions of the ON point and the OFF point can be easily adjusted. In addition, the operation width can be adjusted by changing the displacement amount of the reed switch A44 and the reed switch B48, and the displacement amount between the reed switches is large as in the third embodiment when the operation width is narrower than the operation width of the reed switch alone. If you can not get it, you can handle it.

  Therefore, since the reed switch A44 and the reed switch B48 can be set in accordance with the specified value of the operation width required by the PIP proximity sensor 47, the movement of the magnet 32 can be reliably detected and the proximity sensor with a high yield can be obtained. A control rod drive mechanism position pointing device having

  Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention.

  These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the spirit of the invention.

  These embodiments and their modifications are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

1 ... Reactor pressure vessel (RPV)
8 ... Control rod drive mechanism (CRD)
9 ... Control rod drive mechanism (CRD) housing 32 ... Magnet 33 ... Separation magnet 35 ... Scrum position detection probe (PIP)
36 ... Separation detection probe (SIP)
37 ... Proximity sensor 38 ... Proximity sensor 39 ... Reed switch 40 ... Separation detection probe (SIP) proximity sensor 41, 44 ... Reed switch A
42, 45, 48 ... Reed switch B
43, 46, 47 ... Proximity sensor 51, 52, 54, 55, 59 for scrum position detection probe (PIP) ... Operating area 53, 61 ... ON point 56, 62 ... OFF point 57, 58, 60 ... Combined operating area

Claims (4)

Control rod drive mechanism position indication for detecting the position or state of the control rod drive mechanism for controlling the output of the nuclear reactor from the ON point and the OFF point of the reed switch which is opened and closed by the magnetic force of the magnet arranged in the control rod drive mechanism A device,
As for the reed switch, a reed switch for detecting an ON point of an operating position and a reed switch for detecting an OFF point are individually and independently installed so that their positions can be adjusted
The control rod drive mechanism position pointing device, wherein the reed switch for detecting the ON point of the operation position and the reed switch for detecting the OFF point are arranged so as to be shifted in parallel so as to have different operation regions .   2. The control rod drive mechanism position pointing device according to claim 1, wherein the reed switch for detecting the ON point of the operating position and the reed switch for detecting the OFF point are connected in parallel.   2. The control rod drive mechanism position pointing device according to claim 1, wherein the reed switch for detecting the ON point and the reed switch for detecting the OFF point of the operating position are connected in series. The reed switch, control rod drive mechanism position indicator device of claim 1 or 3, characterized in that the series arrangement of the reed switch to OFF by the magnetic force by the reed switch magnet to ON by the magnetic force by the magnet.

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