Patent Publication Number: US-2020286637-A1

Title: Systems and methods for underwater tool positioning

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to co-pending U.S. Provisional Application 62/813,241, filed Mar. 4, 2019 and incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
       FIG. 1  is selective view of a related art nuclear core shroud  10 , useable in a nuclear reactor like a BWR. Core shroud  10  may be positioned in annulus region  20 , which is an annular space formed between shroud  10  and an inner wall of a reactor pressure vessel (not shown) that receives fluid coolant flow and directs it downward for entry at a bottom of core  30 . Shroud  10  may be a cylindrical structure surrounding core  30  that partitions the reactor into these downward and upward coolant flows on opposite radial sides of shroud  10 . One or more jet pump assemblies  40  may line annulus  20  and direct coolant flow in this manner. 
     After being directed downward past core shroud  10 , coolant may then flow up through core  30  inside shroud  10 . Core  30  is typically populated by several fuel assemblies (not shown) generating heat through nuclear fission during operation, and the coolant exiting core  30  may be quite energetic and potentially boiling. This energetic fluid flows up through and out of core  30  and shroud  10 , potentially into steam separating and drying structures and ultimately to a turbine that drives a generator to convert the energetic flow into electricity. The top portion  15  of shroud  10  may terminate below such drying structures, and various core equipment may rest on or join to shroud  10  about top portion  15 , which may be called a steam dam. One or more gussets  16  may be aligned about top portion  15  of shroud  10  to support or join a shroud head (not shown), chimney, or drying structures. 
     During a reactor outage, such as a refueling outage or other maintenance period, the reactor vessel may be opened and inspected, and internal structures of vessel may be removed. During an outage, loading equipment such as a bridge and trolley above the reactor, and 40-50 feet above core  30  and shroud  10 , may move and load new fuel assemblies in core  30 . Visual inspections of shroud  10 , core  30 , and/or any other component can be accomplished with video or camera equipment operated from the bridge or other loading equipment above the reactor during this time. For example, the positioning and inspection devices of co-owned US Pat Pub 2017/0140844 to Kelemen, published May 18, 2017, incorporated herein by reference in its entirety, may be used in connection with inspections from steam dam  15 . 
     SUMMARY 
     Example methods and embodiment assemblies can position an instrument or tool about a nuclear reactor while completely submerged and without any support or alignment structure, such as a crane, track, motor, bridge, etc. vertically above the assembly where refueling equipment may be working. Example embodiments may include an annular clamp for support from a top of the reactor, an extendible shaft, a motor or other drive to extend or retract the shaft, and/or an articulator secured to an end of the shaft to hold the implement and move the same about any degree of freedom. For example, the extendible shaft may be a telescoping mast joined to a drive motor. Several different articulators are useable in example assemblies, including those with separate gearings for rotation about perpendicular axes and self-leveling wrists to orient tools in confirmed positions. Example embodiments can be locally or remotely powered and controlled through powered and communicative connections. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       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 example embodiments herein. 
         FIG. 1  is an illustration of a related art nuclear power vessel core shroud. 
         FIG. 2  is an illustration of an example embodiment clamp system. 
         FIG. 3A  is an illustration of an example embodiment positioning system from a top perspective.  FIG. 3B  is an illustration of the example embodiment positioning system from a bottom perspective. 
         FIG. 4A  is an illustration of an example embodiment drive from a front.  FIG. 4B  is an illustration of the example embodiment drive from a back.  FIG. 4C  is an illustration of the example embodiment drive from a side. 
         FIG. 5A  is an illustration of an example embodiment mast.  FIG. 5B  is an illustration of a cross-section of the example embodiment mast. 
         FIG. 6A  is an illustration of an example embodiment articulator in a first configuration.  FIG. 6B  is an illustration of the example embodiment articulator in a second configuration. 
         FIG. 7A  is an illustration of another example embodiment articulator showing a bottom portion.  FIG. 7B  is an illustration of the example embodiment articulator. 
         FIG. 8  is an illustration of another example embodiment articulator. 
         FIG. 9A  is an illustration of an example embodiment wrist in a first configuration.  FIG. 9B  is an illustration of the example embodiment wrist in a second configuration. 
     
    
    
     DETAILED DESCRIPTION 
     Because this is a patent document, general broad rules of construction should be applied when reading it. Everything described and shown in this document is an example of subject matter falling within the scope of the claims, appended below. Any specific structural and functional details disclosed herein are merely for purposes of describing how to make and use examples. Several different embodiments and methods not specifically disclosed herein may 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 examples set forth herein. 
     Modifiers “first,” “second,” “another,” etc. may be used herein to describe various items, but they do not confine modified items to any order. These terms are used only to distinguish one element from another; where there are “second” or higher ordinals, there merely must be that many number of elements, without necessarily any difference or other relationship. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element unless an order or difference is separately stated. In listing items, the conjunction “and/or” includes all combinations of one or more of the associated listed items. The use of “etc.” is defined as “et cetera” and indicates the inclusion of all other elements belonging to the same group of the preceding items, in any “and/or” combination(s). 
     When an element is related, such as by being “connected,” “coupled,” “mated,” “attached,” “fixed,” etc., to another element, it can be directly connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly connected,” “directly coupled,” etc. 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 and routing between two devices, including intermediary devices, networks, etc., connected wirelessly or not. 
     As used herein, “axial” and “vertical” directions are the same up or down directions oriented along the major axis of a nuclear reactor, often in a direction oriented with gravity. “Transverse” directions are perpendicular to the “axial” and are side-to-side directions at a particular axial height, while “radial” or “circumferential” directions are also perpendicular to the “axial” in an angular direction, such as about a perimeter of a cylindrical nuclear reactor pressure vessel. 
     As used herein, singular forms like “a,” “an,” and the are intended to include both the singular and plural forms, unless the language explicitly indicates otherwise. Indefinite articles like “a” and “an” introduce or refer to any modified term, both previously-introduced and not, while definite articles like “the” refer to the same previously-introduced term. Possessive terms like “comprises,” “includes,” “has,” or “with” when used herein, specify the presence of stated features, characteristics, steps, operations, elements, and/or components, but do not themselves preclude the presence or addition of one or more other features, characteristics, steps, operations, elements, components, and/or groups thereof. Rather, exclusive modifiers like “only” or “singular” may preclude presence or addition of other subject matter in modified terms. 
     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 single operations described below. It should be presumed that any embodiment or method having features and functionality described below, in any workable combination, falls within the scope of example embodiments. 
     The inventors have recognized that inspections and maintenance operations in a nuclear reactor core consume valuable above-core, and often above-water, space to support and align systems that connect to the actual tools below. This space above the reactor may be shared with a refueling bridge or trolley as well as cranes for core fuel moves and other maintenance during an outage. As such, the inventors have newly recognized a need for tooling that can be operated and supported outside this above-reactor space that is needed for other refueling and maintenance activities, while still allowing alignment and positioning verification, movement across a reactor inner and outer diameter, and support and powering not from this above reactor space. The inventors have developed example embodiments and methods described below to address these and other problems recognized by the Inventors with unique solutions enabled by example embodiments. 
     The present invention is systems and methods for no-overhead reactor maintenance and inspection. 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. 
       FIG. 2  is an illustration of an example embodiment system  100  configured to inspect or operate on structures about a nuclear reactor vessel. As shown in  FIG. 2 , example embodiment system  100  is useable with a positioning device such as steam dam clamp  50  from the incorporated &#39;844 publication as well as U.S. patent application Ser. No. 16/166,881, by Jason D. Mann, filed Oct. 22, 2018 for POSITIONING AND INSPECTION APPARATUSES FOR USE IN NUCLEAR REACTORS, incorporated herein by reference in its entirety. For example, system  100  may be grasped in arm  51  of clamp  50  moving along a nuclear reactor steam dam or other submerged structure. No other support or alignment device may extend upward from system  100 , such that system  100  may be operated entirely from clamp  50  or another submerged vantage without any overhead counterweight or alignment track that may crowd above-core refueling space and operations. 
       FIGS. 3A and 3B  show example embodiment system  100  in isolation, with top drive  110  at a vertical top of mast  150  and articulator assembly  160  at vertical bottom of mast  160 . Example embodiment system  100  is sized to fit both in an annulus as shown in  FIG. 1  between a core shroud and reactor vessel as well as on an inner side of a shroud. While oriented with a longest dimension in the vertical in  FIGS. 3A and 3B , it is understood that example embodiment system  100  may be angled or used in any other orientation. While communications, control, and or electrical power lines may extend vertically down to system  100 , other support or alignment structures are optional, because example embodiment system  100  is useable fully submerged and with self-powering and support from a clamp or other structure. 
       FIGS. 4A-C  are front, rear, and profile schematics of top drive  110  useable in example embodiment system  100 . As shown in  FIG. 4A , tape or cable  114  may extend downward to vertically extend or retract mast  150  shown in  FIG. 4B . Top drive  110  includes motor  111  connected to cable  114 , potentially through spool  112 , to extend and retract cable  114  by rotating spool  112 . Communications and/or power cable  115  may extend up to a power source or controller interface; however, top drive  110  may have local power and be operable wirelessly through wireless control signals, such as radio, Wi-Fi, etc. Camera  113  may similarly be operated and powered through power cable  115  and/or powered and operated wirelessly. As shown in  FIG. 4C , camera  113  may be oriented directly with cable  114  and mast  150  ( FIG. 4B ) to verify exact extension status and transverse or radial alignment of system  100 . Although top drive  110  is shown at a highest vertical position of mast  150  in  FIG. 4B  and elsewhere, it is understood that top drive may be positioned anywhere else, including at a bottom or separately, to provide power to extend and retract mast  150 . 
       FIGS. 5A and 5B  are perspective and cross-sectional schematics of mast  150  useable in example embodiment system  100 . As shown in  FIG. 5A , mast  150  may be a telescopic tube with several sections  151  that are extendible and retractable. Mast  150  may have a generally rectangular or prismatic outer profile, potentially with several insets or notches, to securely seat into a positioning or support structure at a same axial level as a reactor, such as clamp  50  ( FIG. 2 ). Several telescoping sections  151  may be nested within one another to extend and retract several multiples of a length of mast  150 . For example, telescoping sections  151  may descend under force of gravity as cable  114  ( FIG. 4B ), attached to an inner-most mast, extends; reversal of cable  114  may then retract mast  150 , section  151  by section  151 . In this way, mast  150  may be positioned at any desired axial height underwater and/or adjacent to a reactor. As seen in the cross-section of  FIG. 5B , one or more stops  152  may be at a bottom of each sections  151  to prevent overtravel of a next inner section  151 . Connection adapter  152  may be joined to an inner-most section  151  as well as an articulator or tooling. 
     Although mast  150  is shown as the vertical-extending portion of example embodiment system in  FIGS. 2, 3A, and 3B , it is understood that other extendible and retractable bodies may be used instead, such as a rope or tether, or extendible ribbons that become rigid when joined in multiple dimensions when unspooling in the direction of extension, etc. Several different potential articulators are useable with example embodiment systems, as described below. Although articulators are described as providing pan and tilt about vertical and transverse axes, it is understood that mast  150  itself may be rotatable about a vertical or other axis, providing desired positioning. 
       FIGS. 6A and 6B  are perspective views of an example embodiment articulator  160 A in different configurations useable in example embodiment system  100 . As shown in  FIGS. 3A, 3B, 6A, and 6B , articulator  160 A may include a connection post  169  that joins to mast  150  ( FIG. 5A ), such as via connection adapter  152  ( FIG. 5A ). Articulator  160 A may rotate about both a vertical axis and a transverse axis. For example, a rotatable outer frame  162  may join to a body with non-rotatable connection post  169  via planetary gear system  163 . A motor in planetary gear system  163  and matching teethed track and gear may rotate outer frame  162  to any desired degree about a vertical axis, allowing 360-degree panning of tools and instruments attached to the same. And, for example, dial gear system  164  may rotate a tooling or center post  165  to any degree about a transverse axis. One or more motors in gear systems  164  and  163  may provide power to position central post  165  at any desired orientation, and control or power may be received through control connection  161  or a local power source with wireless connection may be used for power and control. 
       FIGS. 7A and 7B  are perspective views of an example embodiment articulator  160 B in different configurations useable in example embodiment system  100 , with  FIG. 7A  showing only the lower portion of example articulator  160 B. As shown in  FIGS. 7A and 7B , articulator  160 B may include a connection post  169  that joins to mast  150  ( FIG. 5A ), such as via connection adapter  152  ( FIG. 5A ). Articulator  160 B may rotate about both a vertical axis and a transverse axis in a similar manner to example articulator  160 A with motor  166  powering planetary and/or worm gear systems with control connection  161  or local and wireless control and power systems allowing control of the same. For example, worm gear system  167  may rotate a tooling or plate arm  168  to any degree about a transverse axis. 
       FIG. 8  is a profile views of another example embodiment articulator  160 C useable in example embodiment system  100 . As shown in  FIG. 8 , articulator  160 C may include a connection post  169  that joins to mast  150  ( FIG. 5A ), such as via connection adapter  152  ( FIG. 5A ). Articulator  160 B may rotate about both a vertical axis and a transverse axis. For example, motor  183  may rotate articulator  160 C on a vertical axis via a rotatable connection to connection post  160 . Top arm  182  and bottom arm  181  may similarly be powered by motor  183  to rotate wrist  185  about a transverse axis, such as by upward or downward rotation of bottom arm  181  while top arm  182  remains static. Wrist  185  may itself move about another vertical axis or skew axis when who oriented by arms  181  and  182  via a planetary and/or worm gear system with control connection  161  or local and wireless control and power systems allowing control of the same. Rotatable mount  186  may further provide rotation about a transverse axis for tooling or central post  187 . 
       FIGS. 9A and 9B  are illustrations of a leveling wrist  170  in use with example embodiment articulator  160 A in two different configurations. As shown in  FIGS. 9A and 9B , articulator  160 A may rotate a top portion of wrist  170  between horizontal and vertical positions, with a lower portion remaining vertical via two-point sliding joint  173 . In this way, the lower portion of wrist  173  may always remain vertical based on the controlled displacement of two-point joint  173  with respect to rotation of articulator  160 A. Additionally or alternatively, a float or level  172  may be paired with release  171  to permit self-leveling. For example, level  172  may always obtain a horizontal orientation when submerged, and release  171  may allow level  172  to achieve this orientation by selectively rotating with respect to the remainder of wrist  170 . 
     Any tool or other device, including cameras, ultrasonic testers, welders, hydrolazers, jets, etc. may be attached to any articulator  160 A-C and/or wrist  170  for desired powering and positioning without using space above the reactor for the same. Power and control signals may be provided through local batteries and/or motors as well as wireless connections, as well as the power and control wiring discussed above. Although power and control wiring my extend vertically above example embodiment system  100 , these are no weight-bearing or aligning and thus require minimal space above the reactor. 
     Example embodiment system  100  may be fabricated of resilient materials that are compatible with a nuclear reactor environment without substantially changing in physical properties, such as becoming substantially radioactive, melting, brittling, or retaining/adsorbing radioactive particulates. For example, several known structural materials, including austenitic stainless steels 304 or 316, XM-19, zirconium alloys, nickel alloys, Alloy 600, etc. may be chosen for any element of components of example system  100 . Joining structures and directly-touching elements may be chosen of different and compatible materials to prevent fouling. 
     Given the variety of example functions described herein, example embodiment systems may be used in several methods to provide desired functionality. It will be appreciated by one skilled in the art that example embodiments may be varied through routine experimentation and without further inventive activity. For example, distinct articulators and wrists may be useable together in some examples, through device placement in examples. Variations are not to be regarded as departure from the spirit and scope of the exemplary embodiments, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.