Patent Application
20230402198
The present disclosure relates to a process and tools to perform reactor pressure vessel nozzle expansion mitigating primary coolant leakage.
This section provides background information related to the present disclosure which is not necessarily prior art.
The inlet nozzles of a reactor pressure vessel pass steam and hot water out of the reactor pressure vessel and experience high thermal variations during reactor operation. Due to the rapid changes in temperature and stress corrosion cracking at the welds that secure the nozzles the welds can experience cracks and, in some cases, leaks around the nozzle penetrations in a boiling water rector. Accordingly, it is desirable to provide an improved method and apparatus for sealing the nozzle penetrations.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The present disclosure is directed to a tool and method for roll expansion of a nozzle in a reactor pressure vessel to mitigate a leak around the nozzle. Roll expansion of the nozzle is an effective and economic solution for sealing a leak in a nozzle of a reactor pressure vessel of a boiling water reactor and can be performed remotely from above the pressure reactor vessel and by using the tool under water.
According to an embodiment of the present disclosure, a nozzle expansion tool includes a frame with a drive system on the frame. A rotary mandrel is drivingly connected to the drive system and is engageable with an expansion roller device. A plurality of vacuum cups are mounted to the frame, and each include a vacuum fitting configured to be connected to a vacuum source.
According to an embodiment of the present disclosure, a depth adjustment mechanism is connected to the expansion roller device and is configured to adjust a distance that the expansion roller device extends from the frame.
According to yet another embodiment of the present disclosure, a method of repairing a crack in a nozzle in a reactor pressure vessel of a boiling water reactor includes suspending a nozzle expansion tool into the reactor pressure vessel. An expansion roller device of the nozzle expansion tool is aligned with an opening of the nozzle. A vacuum cup is supported by an extension system and is engaged with a wall of the reactor pressure vessel. The extension system is retracted to pull the expansion roller device into the nozzle, and a drive motor of the nozzle expansion tool is operated to rotate a rotary mandrel in engagement with the expansion roller device and expanding the nozzle.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore 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. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers 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.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
With reference to
With reference to
With reference to
The front frame member 38 supports a plurality of vacuum cups 46 that each include a vacuum fitting 48. In the embodiment shown, four vacuum cups 46 are provided, although more or fewer vacuum cups 46 can be provided. A plurality of bumper stops 49 are provided adjacent to a respective one of the vacuum cups 46 to limit an amount of depression of the vacuum cups 46.
An additional vacuum cup 50 is provided on the end of a tool locator mechanism 52. The vacuum cup 50 is supported by a pair of guide rods 54 that are slidably received by a guide block 56. The tool locator mechanism 52 includes a drive cylinder 58 and a drive piston 60 that can be activated to extend and retract the vacuum cup 50 and guide rods 54 away from and toward the front frame member 38, as shown in
The tool locator mechanism 52 can be extended in a forward direction to engage the vacuum cup 50 to the side wall of the reactor pressure vessel PRV. Vacuum pressure is applied to the fitting of vacuum cup 50 and the drive piston 60 is then drawn inward to pull the tool 10 toward the wall of the reactor pressure vessel PRV until the vacuum cups 46 engage the wall and to pull the expansion roller device 18 into the opening of the nozzle N. The vacuum cups 46, are supplied with a vacuum pressure via the fittings in order to secure and stabilize the tool 10 relative to the wall when the expansion roller device 18 is operated for expanding the nozzle N.
The frame 12 further includes a drive system support structure 64 that supports the hydraulic motor 14, the planetary gearbox 16, the output coupling 22 and the rotary mandrel 24 relative to the top frame member 36, the side frame member 40 and the front frame member 38. The drive system support structure 64 is moved in a fore and aft direction by the linear actuator 26 (in the form of an air cylinder drive), as shown in
With reference to
With reference to
The depth adjustment mechanism 86, as best shown in
In
In operation, a hoist connected to the suspension cable 44 and the reaction pole 70 are utilized to lower and guide the nozzle expansion tool 10 into a reactor pressure vessel RPV and the vacuum cup 50 is operated to guide and pull the expansion head 30 into an opening of a nozzle N in a sidewall of the reactor pressure vessel RPV. Once the expansion head 30 is fully inserted into the nozzle N, the vacuum cups 46 can be provided with a suction via the vacuum fittings 48 in order to secure and stabilize nozzle expansion tool 10 to the side wall of the reactor pressure vessel RPV. A pair of bubble levels 106, 108 can be mounted to the frame 12 in order to visibly assist in leveling and directing the nozzle expansion tool 10 into place. In addition, the tool locator mechanism 52 can be utilized by expanding the tool locator 52 to an extended position as illustrated in
Once the expansion head 30 is inserted into the nozzle N at a desired depth via adjustment of the depth adjustment mechanism 86, the nozzle expansion tool 10 can be activated by moving the support structure 64 forward and causing the rotary mandrel 24 to contact the expansion rollers 32. Then, the motor 14 is operated by supplying pneumatic or hydraulic fluid to the rotary motor 14 to cause rotation of the expansion head 30 in order to cause a radial force against the rollers 32 while they are rotated within the nozzle N. Rotary motion of the expansion head 30 causes an expansion of the wall of the nozzle N at the desired location in order to repair or mitigate a leak therein.
The nozzle expansion tool 10 is able to be remotely deployed within a reactor pressure vessel RPV and can be utilized to work underwater. The expansion rolling process is intended to be performed until a predetermined torque value is obtained that pursuant to testing, is designed to repair a leak caused by a crack in the nozzle attachment weld. The predetermined torque value can be determined based upon a torque calibration fixture that is used before and after using the tool to ensure that a consistent roll forming torque is applied. The vacuum cups 46, 50 are utilized for stabilizing the nozzle expansion tool 10 during the expansion process.
With reference to
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
