Patent Document

BACKGROUND 
       [0001]    As shown in  FIG. 1 , a nuclear power station conventionally includes a reactor pressure vessel  10  with various configurations of fuel and reactor internals for producing nuclear power. For example, vessel  10  may include a core shroud  30  surrounding a nuclear fuel core  35  that houses fuel structures, such as fuel assemblies,  40 . A top guide  45  and a fuel support  70  may support each fuel assembly  40 . An annular downcomer region  25  may be formed between core shroud  30  and vessel  10 , through which fluid coolant and moderator flows into the core lower plenum  55 . For example, in US Light Water Reactor types, the fluid may be purified water, while in natural uranium type reactors, the fluid may be purified heavy water. In gas-cooled reactors, the fluid coolant may be a gas such as helium, with moderation provided by other structures. The fluid may flow upward from core lower plenum  55  through core  35 . In a water-based reactor, a mixture of water and steam exits nuclear fuel core  35  and enters core upper plenum  60  under shroud head  65 . One or more control rod drives  1  may be positioned below vessel  10  and connect to control rod blades or other control elements that extend among fuel assemblies  40  within core  35 . 
         [0002]    Nuclear reactors are refueled periodically with new fuel to support power operations throughout an operating cycle. During shutdown for refueling, the vessel  10  is cooled, depressurized, and opened by removing upper head  95  at flange  90 . With access to the reactor internals, some of fuel bundle assemblies  40  are replaced and/or moved within core  35 , and maintenance on other internal structures and external structures like control rod drive (CRD)  1  may be performed from outside of reactor  10 . 
         [0003]    As shown in  FIG. 2 , CRD  1  may be mounted vertically within a CRD housing welded to a stub tube  8 , which may extend up into reactor pressure vessel  10 . A spud  46  at a top of index tube  26  may engage and lock into a socket at the bottom of the control element, and index tube  26  may vertically move through action of the CRD hydraulic system to vertically drive or hold the control element. CRD  1  and any control rod element connected via spud  46  form an integral unit that is manually uncoupled by before CRD  1  or control element may be removed from reactor  10 . Below vessel  10 , in an access area or drywell, CRD flange  6  may extend downward from vessel  10  and the CRD housing. CRD  1  may be secured to a face by mounting bolts  88  in flange  6 . A pressure-tight seal can be created by O-ring gaskets (not shown) between flange  6  and any mounting surface. 
         [0004]    One or more CRD hydraulic system lines  81  may pass through ports in flange  6  and work with a CRD hydraulic system for CRD operation, inserting, holding, and/or withdrawing a control element (not shown) via spud  46  at desired positions and speeds for reactor operation. For example, CRD flange  6  may include a withdraw port  82  and an insert port  83  with a check valve  20 . Lines  81  may carry water to insert port  83  and from withdraw port  82 . Withdraw port  82  may serve as an inlet port for water during control rod withdrawal, via vertical downward movement of spud  46 . A piston port  69  may connect to withdraw port  82  in CRD flange  6 . Through piston port  69 , water and hydraulic pressure may be applied through an under-the-collet-piston annulus to collet piston  29  to cause withdrawal, or downward vertical movement of spud  46 . For normal or scram insertion, via vertical upward movement of spud  46 , water may be supplied to inlet port  82 , and withdrawal port  82  may work as an outlet port for water. For rapid shutdown, such as scram insertion with rapid upward movement of spud  46 , check valve  20  may direct external hydraulic pressure or reactor pressure to an underside of drive piston  24 . 
         [0005]      FIG. 3  is a detail view of a bottom of flange  6 , showing an area for insertion of probe  12   a . As shown in  FIG. 3 , piston tube  15  extends upward through the length of CRD  1 , terminating in a watertight cap near the upper end of the tube section and, oppositely, at a threaded end secured by a fixed piston tube nut  16  at the lower end of CRD  1 . A position indicator probe  12   a  may be slid into piston tube  15  from the bottom, potentially sealed into indicator tube within the same. External to piston tube  15 , probe  12   a  can be welded to a plate  12   b  bolted to housing  12  extending from a bottom of flange  6 . Housing  12  may be secured to CRD ring flange  17 , a downward extension of flange  6 , by housing screws  13 . In turn, ring flange  17  may be secured to flange  6  by flange screws  9 . Probe  12   a  and housing  12  attached about fixed piston tube nut  16  as a unit, removable from a bottom of flange  6  together through removal of housing screws  13 . 
         [0006]    Probe  12   a  transmits electrical signals to provide remote indications of control rod position and CRD operating temperature. Probe  12   a  can include a switch support with reed switches and a thermocouple for transmitting electrical signals to provide remote indications of control rod position and CRD operating temperature. The reed switches are normally open but may be closed individually during CRD operation by a ring magnet in the bottom of drive piston  24  ( FIG. 2 ). The reed switches are connected by electrical wires to a connection port  14  that may extend outside of housing  12  and provide wired connectivity to remote operators. Housing  12  may protect any electrical wires extending into connection port  14 . 
         [0007]    In order to uncouple a control element from CRD  1 , a lock plug in spud  46  ( FIG. 2 ) may be raised from below by operators working below reactor vessel  10 . Conventionally, position indicator probe  12   a  is removed from CRD  1  prior to drive removal to allow access to piston tube  15  by an uncoupling tool. Operators typically manually attach an uncoupling tool is to a bottom of CRD  1  and apply force, such as with a jack, to raise piston tube  15 . When the control element is in its “full-out” position directly atop stub tube  8 , drive piston  24  may be separated from a piston head by a small distance. Operators typically observe this positioning directly under vessel  10 , and when the positioning is reached, give an indication for removal by other operators. Raising piston tube  15  by this distance lifts the lock plug out of spud  46 , allowing spud and piston together to be withdrawn and disengage from a control element. 
       SUMMARY 
       [0008]    Example embodiments include systems that attach to control rod drives and selectively bias the same through a joining structure and a driving jack. The joining structures may fit about an outside of the control rod drive and secure a portion of the jack with the stationary control rod drive exterior. A displacement platform of the jack may then be fitted against a moveable control rod drive structure, like a piston tube that can be displaced in a control element decoupling action. For example, a joining structure may include clamping surfaces that fit about a flange of a control rod drive to secure the jack against the piston tube. The jack can then drive the piston tube with several pounds of force relative to the control rod drive against which the jack expands or contacts. This driving can be achieved via a local force that requires no human interaction. Further, attaching and removing the driving jack to a control rod drive may require no tools, little force, and very little time. This permits control rod drive decoupling actions and procedures to be undertaken with minimal expense and effort, including minimal radiation exposure in areas typically having higher doses directly under a reactor. A probe or other instrumentation, as well as local power connections or supplies and receivers/transmitters allow remote operators to control and monitor the action of example embodiments, progress of any decoupling procedure, and/or malfunctions in control rod drive structures. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0009]    Example embodiments will become more apparent by describing, in detail, the attached drawings, wherein like elements are represented by like reference numerals, which are given by way of illustration only and thus do not limit the terms which they depict. 
           [0010]      FIG. 1  is an illustration of a related art nuclear power vessel and internals. 
           [0011]      FIG. 2  is an illustration of a related art control rod drive. 
           [0012]      FIG. 3  is a detail illustration of a related art control rod drive. 
           [0013]      FIG. 4  is an illustration of an example embodiment remote decoupling system. 
           [0014]      FIG. 5  is an illustration of an example embodiment attachment subsystem. 
           [0015]      FIG. 6  is an illustration of an example embodiment piston tube probe. 
           [0016]      FIG. 7  is an illustration of an example embodiment drive subsystem. 
           [0017]      FIGS. 8A and 8B  are detailed illustrations of an example embodiment slide lock for a probe to a drive subsystem. 
           [0018]      FIGS. 9A and 9B  are detailed illustrations of an example embodiment slide lock for an attachment subsystem to a drive subsystem. 
           [0019]      FIGS. 10A and 10B  are illustrations of example embodiment motors useable in drive subsystems. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    This is a patent document, and general broad rules of construction should be applied when reading and understanding it. Everything described and shown in this document is an example of subject matter falling within the scope of the appended claims. Any specific structural and functional details disclosed herein are merely for purposes of describing how to make and use example embodiments or methods. Several different embodiments not specifically disclosed herein fall within the claim scope; as such, the claims may be embodied in many alternate forms and should not be construed as limited to only example embodiments set forth herein. 
         [0021]    It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0022]    It will be understood that when an element is referred to as being “connected,” “coupled,” “mated,” “attached,” or “fixed” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.). Similarly, a term such as “communicatively connected” includes all variations of information exchange routes between two devices, including intermediary devices, networks, etc., connected wirelessly or not. 
         [0023]    As used herein, the singular forms “a”, “an” and “the” are intended to include both the singular and plural forms, unless the language explicitly indicates otherwise with words like “only,” “single,” and/or “one.” It will be further understood that the terms “comprises”, “comprising,”, “includes” and/or “including”, when used herein, specify the presence of stated features, steps, operations, elements, ideas, and/or components, but do not themselves preclude the presence or addition of one or more other features, steps, operations, elements, components, ideas, and/or groups thereof. 
         [0024]    It should also be noted that the structures and operations discussed below may occur out of the order described and/or noted in the figures. For example, two operations and/or figures shown in succession may in fact be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Similarly, individual operations within example methods described below may be executed repetitively, individually or sequentially, so as to provide looping or other series of operations aside from the single operations described below. It should be presumed that any embodiment having features and functionality described below, in any workable combination, falls within the scope of example embodiments. 
         [0025]    Applicants have recognized problems in uncoupling tools and procedures. For example, uncoupling tools typically require manual action for long periods of time directly under reactor vessels. Operators must manually jack up each piston tube and measure/hold them in uncoupling positions while control elements are replaced. Further, uncoupling tools typically include a magnet-actuatable switch that reacts to a ring magnet in a drive piston, giving indication (e.g., a single LED illumination) when a piston tube is raised to a sufficient uncoupling distance. Operators typically have to directly observe this indication and manually react with raising/lowering the tube with a jack and other specialized tools to maintain the same. To overcome these newly-recognized problems as well as others, the inventors have developed easily-installed systems and methods for reliable, remote control rod drive (CRD) actuation and monitoring that may reduce operator burden and radiation exposure. 
         [0026]    The present invention is systems, methods, and subsystems using remotely-operable drives to move reactor components through expansion or retraction of the drives. In contrast to the present invention, the few example embodiments and example methods discussed below illustrate just a subset of the variety of different configurations that can be used as and/or in connection with the present invention. 
         [0027]      FIG. 4  is an illustration of an example embodiment remote decoupling system  100  in use with a CRD  1 , such as an existing drive in a nuclear power reactor  10  shown and described in  FIGS. 1-3 . As shown in  FIG. 4 , example embodiment system  100  may include several subsystems operable together to connect to a lower flange  6  of a CRD  1 , typically under reactor  10 . For example, system  100  may include an example embodiment attachment subsystem  300 , an example embodiment drive subsystem  400 , and/or an example embodiment probe  212 . While example embodiment subsystems  300  and  400  and probe  212  are useable to attach to and decouple CRD  1 , it is understood that other subsystems are useable in example embodiments. 
         [0028]    Attachment subsystem  300  removably secures to CRD  1  via lower flange  6 , permitting force to be remotely and selectively directed to CRD tube  15 .  FIG. 5  is a detail illustration of an example attachment subsystem  300  as it may be installed about a CRD  1 . As shown in  FIG. 5 , attachment subsystem  300  includes at least one clamp arm  310  and a flange sleeve  320 . Clamp arm  310  may extend in an axial direction a length sufficient to span a distance from drive subsystem  400  ( FIG. 4 ) to above a lower flange  6  of CRD  1 , in order to securely join the two. As seen in  FIG. 5 , clamp arm  310  may include a U-shaped end, hook, or other clamping structure that can join around flange  6  and/or bias against a back surface of flange  6 . 
         [0029]    Flange sleeve  320  may be shaped to sit around or over a lower axial end of CRD flange  6 , near where bolts  88  and/or screws  9 / 13  connect terminal pieces to CRD  1 . Any terminal housing structures and/or fixed piston tube nut  16  ( FIG. 3 ) may be removed from CRD  1  prior to installation of attachment subsystem  300 , such as during an outage or at plant fabrication or decommissioning, to expose piston tube  15 . Flange sleeve  320  may include a receptacle  325  for storing fixed piston tube nut  16  during installation and use of example embodiments, to prevent misplacement and allow easy accounting for and reassembly with fixed piston tube nut  16 . Flange sleeve  320  may also sit below flange  6 , about shoot-out steel, probe  212 , or another structure that connects to flange  6  to achieve the same securing as a direct sleeve-flange connection. 
         [0030]    With CRD lower flange  6  and piston tube  15  free and accessible, flange sleeve  320  may be seated against lower flange  6  in a vertical or axial direction securely except potentially to permit rotation about a vertical axis for proper aligning. Flange sleeve  320  may include a number of sleeve wings  321  for each clamp arm  310 . Clamp arm  310  may be joined to flange sleeve  320  at a hinge  311  on sleeve wing  321  or other connection point that permits movement for removable installation and securing. For example, hinge  311  on sleeve wing  321  may permit clamp arm  311  to rotate about a single axis relative to flange sleeve  320 . If sleeve wing  321  is relatively narrow, flange sleeve  320  and clamp arm  310  joined thereto may be rotated together about a length axis of CRD  1  between bolts  88  for desired positioning while avoiding the same. 
         [0031]    As shown in  FIG. 5 , clamp arm  310  may initially be collapsed inward at a free lower end/outward at a clamping end during installation such that clamp arm  310  and flange sleeve  320  seat completely onto and over lower flange  6  of CRD  1  and rotated into position about the same without blocking by clamp arm  310 . Then clamp arm  310  may be expanded so as to rotate and seat a U-shaped or clamping end against a back of flange  6 , as shown by the terminal inward arrow in  FIG. 5 . 
         [0032]    Clamp arm  310  may include a selective lock that secures attachment subsystem  300  to CRD  1  following installation. For example, as shown in  FIG. 5 , a rotatable locking edge  312  may be positioned on a telescoping or extendable end of clamp arm  310 . Locking edge  312  may include a variable diameter that is shaped at some portions to seat into a locking notch  322  in a corresponding guide ear  321 . In this way, after one or more clamp arms  310  are extended over and rotated to seat against flange  6  to secure subsystem  300 , locking edges  312  may be extended vertically to locking notches  322  and rotated (in a vertical axis perpendicular to that of hinge  311 ) into locking notches  322 . For example, locking edges  312  may have a varying diameter that allows edges  312  to be moved with arm  310  vertically (long, straight double arrow in  FIG. 5 ) to locking notches  322  without being blocked by guide ear  321  when arm  310  is rotated outward and secured to flange  6 . The varying diameter may then be rotated (rotational double arrow in  FIG. 5 ) at notch  322  to engage notch  322  and prevent any further movement of arm  310  except rotation in the vertical axis to “unlock” the edge  312  from notch  322 . The resulting installation is shown in  FIG. 3 , with arms  310  substantially vertical and parallel with CRD  1 . 
         [0033]    The movements and interrelation of parts of example embodiment attachment subsystem  300  may allow easy and quick installation of attachment subsystem  300  to flange  6  of CRD  1  without any vertical slippage. Subsystem  300  of  FIG. 3  may also be easily removed through rotation, then extension, then rotation of clamp arms. This easy and reliable installation and removal may permit minimal personnel effort and work-time about CRD  1  to install and use example embodiments. As such, example embodiments may reduce radiation exposure and increase productivity in control rod operations and maintenance. 
         [0034]    Although example embodiment attachment subsystem  300  is shown with two clamp arms  310  that reach around flange  6  to vertically secure to the CRD  1 , it is understood that any number of clamp arms  310  and/or other attachment devices, including magnets, adhesives, cables, screw clamps, hydraulics, etc. may be used to attach various systems and subsystems in example embodiments to CRD  1 . 
         [0035]      FIG. 6  is an illustration of an example embodiment probe  212  useable in example embodiment system  200 . Example embodiment probe  212  is sized and shaped to fit within piston tube  15  ( FIG. 4 ). As shown in  FIG. 4 , example embodiment probe  212  may be inserted into piston tube  15  before or after installation of attachment subsystem  300  when nut  16  is removed and stored in receptacle  325  or piston tube  15  is otherwise accessible. Probe  212  may include threads or other securing structures that permit a removable joining with piston tube  15 , such that a position of probe  212  accurately reflects a vertical displacement of piston tube  15  in CRD  1  during decoupling. Further, any securing structure between probe  212  and piston tube  15  may be sufficiently robust to transfer thousands of pounds of forces in upward and downward vertical directions to piston tube  15  without slippage or breaking in the even probe  212  is the only direct connection to piston tube  15 . 
         [0036]    As shown in  FIG. 6 , example embodiment probe may include a stem  213  with electronics, such as Hall effect sensors, magnetostrictive sensors, or magnetic members, that can detect a position of stem  213  and probe  212  in piston tube  15 . For example, stem  213  may be lined with sensors that detect ring magnets within a piston or piston tube  15  of a conventional CRD  1  ( FIG. 2 ). Based on magnetic field strength at various vertical positions, probe  212  may determine a degree of insertion and/or extension of piston tube  15 , similar to a determination made in conventional CRD decoupling. 
         [0037]    Electronics in stem  213  may connect to a probe port  215  in a spring-biased base  214  that extends out of piston tube  15  in example embodiment probe  212 . For example, one or more pins or other known communicative interfaces in probe port  215  may transmit signals to other components for proper decoupling measurement. Spring-biased base  241  may connect to other mechanical or communications systems to ensure that example embodiment probe  212  remains seated in piston tube  15  to accurately measure vertical movement of the same decoupling. 
         [0038]    As shown in  FIG. 4 , with probe  212  and attachment subsystem  300  in place and secured to lower flange  6  of CRD  1 , example embodiment drive subsystem  400  may be installed to probe  212  and attachment subsystem  300  in order to provide remote communications and movement of piston tube  15  for decoupling. 
         [0039]      FIG. 7  is a detailed illustration of drive subsystem  400 . As shown in  FIG. 7 , drive subsystem  400  may include a base  450 , connection arm  410 , and jack platform  415 . Each connection arm  410  may match location of a terminal of installed clamp arm  310  from example embodiment attachment subsystem  300 , and jack platform  415  may match a location of example embodiment probe  212  and/or piston tube  15  in a CRD. In this way, example embodiment drive subsystem may be useable with other example embodiments. Of course, other dimensioning and configuration of example embodiments is possible to successfully interact with a control rod drive. 
         [0040]    Each connection arm  410  may receive or otherwise attach to a terminal end of clamp arm  310  in order to join example embodiment subsystems  300  and  400  and transfer force to piston tube  15 . For example, connection arm  410  may define a receptacle  412  into which a corresponding clamp arm  310  ( FIG. 5 ) fits. A locking structure, such as slide lock  411  may permit securing a lower end of clamp arm  310  in receptacle  412 . 
         [0041]    Similarly, jack platform  415  may receive or otherwise attach to a probe  212 , such as via spring-biased face  214  of probe  212  ( FIG. 6 ). For example, jack platform may define a receptacle  417  into which a corresponding probe  212  ( FIG. 6 ) fits. A locking structure, such as slide lock  416  may permit securing a lower end of probe  212  in receptacle  417 . Jack platform  415  may also directly attach to piston tube  15  or indirectly attach to piston tube  15  through probe  212 ; similar connection structures are useable between such elements. 
         [0042]      FIGS. 8-9  are details of receptacles  412  and  417  showing examples of simple locking structures in action. As seen in  FIGS. 8A and 8B , slide lock  416  may be easily movable in a depth dimension in jack platform  415 . Slide lock  416  may define a variable-shaped gap where it intersects receptacle  417 , such that an edge of slide lock  416  extends into receptacle  417  when fully seated into jack platform  415 . When withdrawn in the depth direction, the variable-shaped edge of slide lock  416  may not extend into receptacle  417 . When paired with a notch in probe  212 , slide lock  416  may thus secure probe and jack platform  415  together, transferring force between the two and/or piston tube  15 , to which probe  212  and/or jack platform  415  may be secured. As shown in  FIGS. 8A-B , jack platform  415  may further include a communications interface  418  that receives information from probe  212  and/or provides power and information to probe  212 . For example, communications interface  418  may be pin receptacles that uniquely fit pins in probe port  215  on a face of example embodiment probe  212 . 
         [0043]    As seen in  FIGS. 9A and 9B , slide lock  411  may be easily movable in a depth dimension in connection arm  410 . Slide lock  411  may define a variable-shaped gap where it intersects receptacle  412 , such that an edge of slide lock  411  extends into receptacle  412  when fully seated into connection arm  410 . When withdrawn in the depth direction, the variable-shaped edge of slide lock  411  may not extend into receptacle  412 . When paired with a notch in clamp arm  310  ( FIG. 5 ), slide lock  411  may thus secure attachment subsystem  300  and connection arm  410  together, ensuring example embodiments and CRD  1  remain in relatively static positions, with the exception of any relative movement of jack platform  415 , probe  212 , and piston tube  15 . 
         [0044]    Example embodiment subsystems  300  and  400 , as shown in FIGS.  5  and  8 - 9 , may take advantage of relatively simple connection structures that reliably and statically interconnect CRD  1  and example embodiment system  100 , while permitting relative movement of jack platform  415  and piston tube  15 . These simple connection structures may require no separate tooling; for example, all connection structures in FIGS.  5  and  8 - 9  may be directly installed and manually operated through pushing, pulling, or twisting the connectors to lock them into place by hand. This relatively simple installation may permit relatively quick and unencumbered installation and securing of example embodiment system  200  with no additional tools required, speeding work time and easing work burden about CRD  1 , which may be a higher radiation area. 
         [0045]    Returning to  FIG. 7 , base  450  may include a face with interactive structures for communications and manual interaction. As shown in  FIG. 7 , a communications and/or power port  451  may allow connection to a wire, pinned interface, or other connector for information transmission from example embodiments during decoupling. For example, port  451  may be interfaced with probe  212  via communications interface  418  and probe port  215 , and data and/or operation instructions to/from probe  212  may be transacted through port  451 . Port  451  may further receive instructions or operations signals from a remote user for translation into decoupling actions to be taken, including raising or lowering jack platform  415 . Port  451  may further accept external power connections to power various parts of example embodiment system  200 . Or port  451  may be internal or missing entirely, and communications and operation may be provided through wireless communication over WiFi or other electromagnetic communication. In such an example, base  450  may include a local power source such as a battery to drive operations without external power sources. 
         [0046]    Base  450  may further include operations indicators  452  that show a status of example embodiment system  200 . For example, operations indicators  452  may include LED lights reflecting power status, initialization routines, successful data connection, errors, etc. A power button  453  may provide manual, local activation capabilities, and an initialization button  454  may provide internal testing and initialization to confirm proper connection with other systems and/or piston tube  15 . Of course, indicators  452 , and power/initialization button  452 / 454  may be absent, and such functionality may be provided remotely through wireless communications with a receiver in base  450  or via a cable connected to port  451 , for example. 
         [0047]    Through relatively simple setup, example embodiment system  200  may be fabricated by installing attachment subsystem  300 , inserting probe  212  (if any), and connecting them to drive subsystem  400  through relatively simple and reliable joining mechanisms. Base  450  may then be connected to remote operations and/or operated locally. Removal, such as following decoupling, may be achieved by reversing these actions in example embodiment system  200 . As such, total assembly and disassembly may be relatively simple and consume minimal time, and personnel may vacate the area of CRD  1  during the actual uncoupling procedure, which may be achieve through remote operation of example embodiment system  200  discussed below. Although various types of physical and communicative connections and securing structures, as well as different subcomponents have been discussed and interrelated in the above example embodiments, it is understood that other joining mechanisms, communications devices and protocols, and securing structures may be used in example embodiments while still allowing remote decoupling action and monitoring of the same. 
         [0048]    In order to perform a decoupling operation on typical CRDs  1 , piston tube  15  must be raised by an inch or more using upwards of approximately 1000 pound of force. As such, jack platform  415  raises and lowers vertically relative to base  450  in order to similarly move piston tube  15  to which it may be rigidly joined in the vertical/axial direction. Jack platform  415  may exert large amounts of force through proper gearing and/or induction driving structures in base  450 , for example, over the required distance. Such raising and lowering may be performed in the absence of any local personnel action through remote operation of example embodiment system  200 . 
         [0049]      FIGS. 10A and 10B  are illustrations of an example embodiment motorized drive in base  450  to provide for raising jack platform  415  ( FIG. 4 ) under sufficient force and distances. As shown in  FIG. 10A , a motor  465  may be mounted inside base  450 . Motor  465  may be an electric motor powered by a local battery or external power source. Motor  465  may have sufficient wattage or torque, or be connected through sufficient gearing, to create over 1000 pounds of force in jack platform  415  in an upward and downward vertical direction. For example, motor  465  may connect to a worm gear  460  that converts force from motor  465  to controlled vertical movement in a geared piston in jack platform  415  without slippage or reversal/overshoot under action of motor  465 . Motor  465  may be actuated remotely, such as through wireless or electrical signal from a user positioned in a control room or offsite, allowing jacking of piston tube  15  remotely. 
         [0050]    Motor  465  may be selectively engaged, such as via an engagement assembly  466  that moves motor  465  in a depth direction to engage or disengage with worm gear  460 . For example, by driving a screw in engagement assembly  466 , a user or automatic function may disengage or engage motor  465  as desired. As shown in  FIG. 10B , disengagement of motor  465  by turning a screw in assembly  466  to disconnect gearings of motor  465  and worm gear  460  may allow a user to manually operate work gear  460  in the instance of motor failure or necessary manual intervention. Motor  465  may further include a cycle counter or other sensor that relates its position, torque, and/or velocity to location, force, and/or speed of jack platform  415 . Such data may also be communicated to remote users through communications ports or interfaces in example embodiments, such that users may remotely monitor jack platform position, potentially independent of any piston tube sensor magnetic readings, in order to monitor progress and confirm or calibrate other sensors. 
         [0051]    As seen in  FIG. 4 , through connection of various subsystems among example embodiments, a relatively large amount of force may be selectively applied to piston tube  15  in CRD  1  in an upward or downward vertical direction. This force may be controlled by operators stationed remotely, allowing movement of piston tube  15  for decoupling without direct human action or monitoring, thus reducing human radiation exposure and workload. Further, operations of example embodiments, including system status/malfunction, exact location of probe  212  and thus piston tube  15  in CRD  1 , height and movement direction of jack platform  415 , etc. may be transmitted to remote operators to better inform their actions and other decoupling activities, such as in-core control element movements and removal from any unlocked spud. 
         [0052]    Although a selectively-engaged motor  465  may be useable to provide the remotely-actuated force in example embodiments to achieve conscious uncoupling through relative movement, it is understood that any number of different force-creating devices can be used in example embodiments. For example, pneumatic cylinders or direct induction drives can be used to create desired vertical movement of platform  415  remotely. 
         [0053]    Example embodiments and methods thus being described, it will be appreciated by one skilled in the art that example embodiments may be varied and substituted through routine experimentation while still falling within the scope of the following claims. For example, a variety of control rod drive designs are compatible with example embodiments and methods simply through proper dimensioning of example embodiments—and fall within the scope of the claims. Such variations are not to be regarded as departure from the scope of these claims.

Technology Category: 4