Abstract:
Example embodiments are directed to jet pump inspection apparatuses including an encoded probe driver coupled to a guide funnel. In an example embodiment, the encoded probe driver and the guide funnel are located on the body of the apparatus in order to decrease the time required for inspection, thereby limiting exposure to personnel of radioactive contamination.

Description:
BACKGROUND 
     1. Field 
     Example embodiments generally relate to a jet pump inspection apparatus including an encoded probe driver coupled to a hybrid form guide funnel that introduces probe cable assemblies to boiling water reactor (BWR) jet pump assemblies. 
     2. Description of Related Art 
     Bores such as pipes or cylindrically shaped equipment are often submerged in a pool of water or other liquid. There is often a need to have a maintenance tool or inspection probe delivered into the submerged bore. For example, a reactor pressure vessel (RPV) of a boiling water reactor (BWR) typically has submerged bores that need to be inspected during maintenance routines. Hollow tubular jet pumps having internal bores are positioned within an annulus to provide the required reactor core water flow. The jet pump includes an upper portion, known as the inlet mixer, and a lower portion, known as the diffuser. The inlet mixer and the diffuser, due to their large size, are formed by welding a plurality of cylindrical and conical sections together. Specifically, respective ends of adjacent cylindrical sections are joined with a circumferential weld. During operation of the reactor, the circumferential weld joints may experience inter-granular stress corrosion cracking (IGSCC) and irradiation assisted stress corrosion cracking (IASCC) in weld heat affected zones. This can diminish the structural integrity of the jet pump. 
     It is important to examine the welds of the jet pump inlet mixer and diffuser periodically to determine whether any cracking has occurred. While visual examinations in the annulus or region between a shroud and a pressure vessel wall can be performed, these examinations are likely to be only partial inspections due to access limitations in the annular region of the reactor. As such, the examination of the jet pump welds are often examined by an inspection tool positioned inside of the jet pump inlet mixer and jet pump diffuser. Such inspection tools perform ultrasonic and/or eddy current examinations of jet pump welds from inside the jet pump inlet mixer and diffuser in a nuclear reactor. 
     Typically, operational personnel located on a 360° service platform above the surface of the pool manipulate poles and other mechanical suspension devices to position a funnel to the inlet mixer of each jet pump to be inspected. In some cases the tool is deployed from a refuel bridge or auxiliary bridge. For a single BWR, there are typically 20 jet pumps, but a BWR can have up to 24. Prior to installing the delivery tool into the pool, the probe head with cable is loaded into the delivery tool. Once the delivery tool is positioned at the inlet of a jet pump inlet, the funnel is secured to the inlet using a pneumatic clamp. As the inlets to the jet pumps are submerged, often up to 50 feet under the surface of the pool, the manual manipulation of these poles and the funnel is difficult and time consuming. 
     After the tool delivery system is mated with the inlet mixer, the inspection tool or probe is lowered into a calibrated reference sleeve to calibrate the ultrasonic probes prior to inspection. The scan head is then lowered into the inlet of the pump to commence with the inspection. Once the first adjacent jet pump is inspected, the scan head is positioned into the calibration sleeve and post inspection calibration is performed. The tool delivery system is then disconnected and moved to the next pump. The attachment, calibration, insertion, and inspection operations are repeated until all jet pumps have been inspected. Often the operator will utilize at least one submerged camera to aid in the movement, manipulation, attachment, and detachment of the submerged components. 
     The probe driver is located as close as possible to the inlet of the pump to reduce the position error resulting from cable stretch between the positioning device and the scan head. In other systems and methods, a probe driver assembly can be located above the pool surface. Such a probe driver assembly provides for axial movement of the inserted probe by using a take-up reel and a set of pinch wheels to raise and lower the probe head. However, such systems have often been considered difficult to maintain accurate position. 
     As such, current systems and methods for inspecting the inside of a submerged bore such as a nuclear reactor jet pump that can be submerged 50 feet below the surface of a water pool are difficult, time consuming, and costly. Often such tasks become a critical path item during a nuclear reactor reloading process. As such, any opportunity for reducing the required time can decrease the amount of off-line or down-time of the reactor and therefore provide significant cost savings to the reactor operator as well as reduced dose to operators and technicians. 
     SUMMARY 
     Example embodiments are directed to a jet pump inspection apparatus that introduces probe cable assemblies to boiling water reactor (BWR) jet pump assemblies from a platform without the need for a submarine assembly. Advantages include allowing a probe head to be removed for servicing without the need to remove or reposition the entire delivery apparatus, tool or submersible, reduced inspection time and/or smaller footprint to impede critical path activities such as fuel moves. 
     Example embodiment jet pump inspection apparatuses may include an encoded probe driver and guide funnel on the body of the apparatus in order to decrease the time required for inspection, thereby limiting exposure to personnel of radioactive contamination. 
    
    
     
       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 a side view of an example embodiment jet pump inspection apparatus. 
         FIG. 2  is an isometric view of the pole attachment as illustrated in  FIG. 1 . 
         FIG. 3  is an isometric view of the probe driver coupled to the pole attachment as illustrated in  FIG. 1 . 
         FIG. 4  is an isometric view of the pole attachment and probe driver coupled to the guide funnel as illustrated in  FIG. 1 . 
         FIG. 5  is an isometric view of the guide latch as illustrated in  FIG. 1 . 
         FIG. 6  is a side view of an example embodiment jet pump inspection apparatus as illustrated in  FIG. 1  coupled to an inlet of a submerged nuclear reactor jet pump. 
     
    
    
     DETAILED DESCRIPTION 
     Detailed illustrative example embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. The example embodiments may, however, be embodied in many alternate forms and should not be construed as limited to only example embodiments set forth herein. 
     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. 
     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.). 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the language explicitly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. 
       FIG. 1  is a side view of an example embodiment jet pump inspection apparatus. The jet pump inspection apparatus includes a body  101 . The body  101  has a pole attachment  12 , a probe driver  14 , a guide funnel  10 , a calibration tube  15  and a guide latch  16 . The body  101  may be tubular as illustrated in  FIG. 1 , and protects drive elements from damage during use of the apparatus. In an example embodiment, the body  101  is constructed of high strength aluminum. 
     The guide funnel  10 , the probe driver  14  and the calibration tube  15  are located along the body  101 . The pole attachment  12  is located on one end of the body  101  and the guide latch  16  is located on an opposite end of the body  101 . 
     The functions of the jet pump apparatus are remotely controlled via a manned computer based operation console  300 . The console  300  may include, for example, a central processing unit (“CPU”)  305 , memory unit  308 , input console  304 , and/or a display unit  302 . The CPU  305  may be electrically connected to the memory unit  308 , input console  304 , and display unit  302  so as to enable communication between them. The technician manually operates the air control station  310  for pneumatic functions of the apparatus. The CPU  305  is equipped with a motion control system  320  for an encoded dc servo motor, which will be explained in further detail below. The console  300  is connected to the inspection apparatus via up to 200 feet long electrical and pneumatic umbilicals  150  to allow for remote operation by the technician. 
       FIG. 2  is an isometric view of the pole attachment as illustrated in  FIG. 1 . Referring to  FIG. 2 , the pole attachment  12  is located on one end of the body  101  and allows for the jet pump inspection apparatus to connect with at least one conventional handling pole (not shown) to be handled by a technician. The pole attachment  12  is the lid of the probe driver  14 , which will be described in further detail with reference to  FIG. 3  below. In example embodiments, a predetermined or given number of handling poles at varying lengths will be utilized in order to deploy the jet pump inspection apparatus. The pole attachment includes a plate  12   a  having a plurality of bolts around the circumference of the plate  12   a  to connect the plate  12   a  to the probe driver  14  and a waterproof electrical connection in the center of the plate  12   a  configured to connect to a motor in the probe driver  14 , which will be described in further detail below. 
     A connector  12   b  extends from the surface of the plate  12   a  to connect to the at least one handling pole. The connector  12   b  may be a hollow cylinder including a j-shaped slot interlocking with a peg of the at least one handling pole. The plate  12   a  may be in the shape of a disc except for an extension from the plate  12   a . The extension of the plate  12   a  includes a slot  12   c  and up to four bolts along the sides of the extension for attachment to the probe driver  14 . The four bolts anchor one end of a double acting pneumatic cylinder (not shown), which is remotely controlled via the air control station  310  of the console  300 , within a body  14   e  of the probe driver  14  (see  FIG. 4 ) that levers the probe driver  14  open and closed for loading and unloading a probe cable (not shown) into the probe driver  14 . The plate  12   a  of the pole attachment  12  may be up to one-half an inch thick. 
       FIG. 3  is an isometric view of the probe driver coupled to the pole attachment as illustrated in  FIG. 1 . Referring to  FIG. 3 , the probe driver  14  is located near one end of the jet pump inspection apparatus and includes a body  14   e . The probe driver  14  provides for axial movement of a probe cable by using a set of wheels  14   a  to raise and lower a probe head of the probe cable. The probe cable extends from the waterproof connection of the plate  12   a  through the set of wheels  14   a  located along the side of the body  14   e . The probe driver  14  extends along the entire length of the apparatus and exits through the bottom of the guide latch  16 . 
     A separate t-hook assembly (not shown) may be optionally utilized if the probe head of the probe cable needs attention. The T-hook assembly may be deployed to help remove the probe from the probe driver  14 . If the T-hook assembly  14   b  is utilized, the T-hook assembly  14   b  of the probe driver  14  can be rotated by the user to position a finger of the T-hook assembly  14   b . The finger of the T-hook assembly  14   b  pushes the probe cable between the wheels  14   a  of the probe driver  14 . 
     A slot  14   b  may be located above the set of wheels  14   a . The probe driver  14  can provide further control of the elevation of the probe head by integration with a precision DC servo motor (not shown), which is remotely controlled via the motion control system  320  of the console  300 . The motor may be equipped with a high resolution encoder  14   f  located within the upper most cylinder of a housing  14   c  of the probe driver  14 . The housing  14   c  is connected to an upper surface of the body  14   e  of the probe driver  14  by a set of bolts. The upper most cylinder of the housing  14   c  may be larger in diameter than a lower most cylinder of the housing  14   c . The encoder  14   f  gives the exact location of the probe head based on the number of revolutions of the motor. 
     In example embodiments, the probe driver  14  may have a set of wheels  14   a , for example, four wheels  14   a  as illustrated in  FIG. 3 . The wheels  14   a  of the probe driver  14  are made of butyl rubber, joined through a common transmission that synchronously drives all of the wheels at the same rate of speed in a user defined direction (e.g., axially up/down). 
     The pneumatic cylinder (not shown), which is remotely controlled by the air control station  310  of the console  300 , affixes from the plate  12   a  of the pole attachment  12  to a lever point on the wheels  14   a  to actuate the wheels  14   a  from an open to closed position allowing the probe cable to be loaded and unloaded into the probe driver  14 . The guide funnel  10  includes a L-shaped bracket  14   d  that is configured to connect to the side of the probe driver  14 . 
       FIG. 4  is an isometric view of the pole attachment and probe driver coupled to the guide funnel as illustrated in  FIG. 1 . Referring to  FIG. 4 , the guide funnel  10  is on the body  101  beneath the probe driver  14 . The guide funnel  10  is in line with the slot  14   d  on the same side of the apparatus. The guide funnel  10  is used to guide the probe head of the probe cable into the tubular body  101  of jet pump inspection apparatus at a predetermined or given depth. If the probe head needs to be serviced, the jet pump inspection apparatus can remain in position due to the access to the probe head from the guide funnel  10 . The T-hook assembly may facilitate removal of probe head for service and allow the inspection apparatus to remain in position. 
     The probe driver  14  and the guide funnel  10  are located on the body  101  (see  FIG. 1 ) of the jet pump inspection apparatus rather than on the pool surface as in the conventional art in order to reduce errors caused by up to 50 feet of cable being stretched to the surface of the jet pump inspection apparatus. The probe driver  14  may be mounted to an inlet of a submerged nuclear reactor jet pump  202  while underwater (described below with regards to  FIG. 6 ). After the probe head is positioned in the guide funnel  10 , the T-hook  14   b  allows the user to guide the probe cable into the probe driver  14  as explained previously with reference to  FIG. 3 . 
     Referring back to  FIG. 1 , the other end of the body  101  is connected to a guide latch  16  via a calibration tube  15 . The calibration tube  15  is located inline with the jet pump inspection apparatus and allows for calibration of the probes before and after a conventional scan process. The calibration tube  15  also functions as a connector that allows for the body  101  and the guide latch  16  to be disconnected. As such, the body  101  and the guide latch  16  are detachably attached to one another as will be described in more detail below. 
       FIG. 5  is an isometric view of the guide latch as illustrated in  FIG. 1 . Referring to  FIG. 5 , the guide latch  16  is connected to the calibration tube  15  near the bottom of the apparatus. A guide latch  16  is a clamping or engagement mechanism including one or more engagement members  16   a  and one or more opposing engagement members  16   b . A gap  16   c  is formed between engagement members  16   a  and  16   b  and is configured to enclose one or more types or shapes of inlets. The engagement members  16   a  and  16   b  move together and clamp an object or surface located in gap  16   c . A pneumatic or air-powered latching actuator  16   d , which is near the upper surface of the guide latch  16  and remotely controlled via the air control station  310  of the console  300 , engages one or both of the engagement members  16   a  and  16   b  such that one or both move together and clamps an object or surface located in gap  16   c.    
     In practice, the engagement members  16   a  and  16   b  and latching actuator  16   d  are dimensioned and arranged to couple to an inlet of a submerged nuclear reactor jet pump  202  of a nuclear reactor  200 , which will be described in more detail below with reference to  FIG. 6 . For example, in one embodiment, the latching actuator  16   d  is an air cylinder actuator that receives air pressure from an external source. In other embodiments, the latching actuator  16   d  may be a motor or similar device for closing gap  16   c  so that engagement members  16   a  and  16   b  compressively couple to the inlet. When actuated, the latching actuator  16   d  compresses the opposing engagement member  16   b  towards engagement member  16   a  to clamp onto a lip or edge of a jet pump  202  positioned within gap  16   c  (see  FIG. 6 ). The encoder  14   f  of the probe driver  14  relays the position of the probe such that the jet pump inspection apparatus is in the proper location to attach to the jet pump inlet. 
     The entire jet pump inspection apparatus may weigh up to 49 pounds when dry and up to 27 pounds when wet and the entire length of the jet pump inspection apparatus may be in a range between about 119 inches-about 128 inches. 
     For clarity,  FIG. 6  illustrates an example embodiment jet pump inspection apparatus as illustrated in  FIG. 1  coupled to an inlet  204  of a submerged nuclear reactor jet pump  202  of a nuclear reactor  200 . A technician located on a 360° service platform above the surface of the pool of the nuclear reactor  200  will manipulate the at least one handling pole to couple the apparatus to an inlet of each jet pump to be inspected. In some cases, the tool is deployed from a refuel bridge or auxiliary bridge. Prior to deploying the apparatus into the pool, the probe head with cable is loaded into the apparatus. 
     The jet pump inspection apparatus is lowered into the pool of the nuclear reactor  200  with subsequent additions of handling pole segments, the length of each being up to ten feet, until the jet pump inspection apparatus reaches a docking elevation near the jet pump inlet  204  (e.g., about 50-60 feet from the pool surface). 
     A camera system (not shown) may be used by the technician for viewing the end of the apparatus, e.g., the guide latch  16 , while manipulating the handling poles to guide the apparatus until mated to the lip of the inlet  204 . Once the apparatus is on the lip, the technician will notify the operator of the console  200  to engage the latching function of the guide latch  16 . After the latching function is visually verified with the camera in the engaged state, the technician will notify the operator of the console  200  that calibration may commence through the inline calibration standard. Once the calibration is complete, the operator will instruct the console  200  to drive the probe cable down from the bottom of the guide latch  16  into the jet pump  202  and to the lowermost weld  206  to commence ultrasonic interrogation of all the welds contained in the jet pump  202 . The operator sets the motion controls or parameters for the console  200  to commence scanning (e.g. the elevation to scan, how fast to scan, etc.). 
     It will be understood that the present invention provides for a remotely controlled apparatus used for the inspection of a jet pump of a boiling water reactor. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.