KR20230133941A - Apparatus and method for locating a calandria tube - Google Patents

Abstract

A method of inserting a calandria tube into a nuclear reactor includes engaging an insertion tool with the inner surface of the calandria tube, inserting a portion of the calandria tube through the insertion tool through the first calandria tube sheet bore, Inserting the guiding tool into the inner surface of the calandria tube, and guiding a portion of the calandria tube through the insertion tool and the guiding tool through the second calandria tube seat bore.

Description

Apparatus and method for locating a calandria tube {APPARATUS AND METHOD FOR LOCATING A CALANDRIA TUBE}

This application relates to U.S. Provisional Patent Application No. 62/524,330, filed on June 23, 2017, and Romanian Patent Application a 2018 00139, filed on February 28, 2018, entitled “APPARATUS AND METHOD FOR LOCATING A CALANDRIA TUBE” Claim all interests, including priority rights.

Accordingly, these applications are incorporated by reference in their entirety.

The following application relates to inserting calandria tubes into a nuclear reactor, and in particular to an apparatus and method for inserting a calandria tube into a nuclear reactor using an insertion tool and a guiding tool.

Nuclear reactors have a limited operational life. For example, the second generation CANDU ^TM type reactors (“CANada Deuterium Uranium”) are designed to operate for approximately 25 to 30 years. After this time, the existing fuel channel can be removed and a new fuel channel installed. As an alternative to taking a reactor out of service, performing this "retubing" process can significantly extend the life of the reactor. The reactor tube replacement process involves the removal of a number of reactor components and also includes various other activities such as reactor shutdown, preparation of vaults, and installation of material handling equipment and various platforms and equipment supports. The removal process may also include removal of the closure plug, placement of the hardware assembly, disconnection of the feeder assembly, cutting of the bellows, removal of end fittings, release and removal of the calandria tube insert, and cutting and removal of the pressure tube and calandria tube. may include.

Once the removal process is complete, a testing and installation process is usually performed. For example, tube sheets located at each end of the reactor may include a plurality of bores. Each of the plurality of bores supports a fuel channel assembly spanning between the tube sheets. Once the fuel channel assembly is removed, each tube seat bore is inspected to ensure that the tube seat bore is in compliance with specifications and that the tube seat bore is ready for insertion of a new fuel channel assembly.

After the tube sheet is confirmed to be in proper condition, the calandria tube, pressure tube, end fittings and other components can be reinstalled into the bore. For each fuel channel assembly, part of this process involves rolling the end of the calandria tube up to the tube seat of the calandria (e.g., using a deformable calandria insert), inserting the end fitting body into the bore, and sealing the pressure tube. Rolling the end into the end appendage body and inserting the end appendage liner into the end appendage.

In some embodiments, the present invention provides a method of inserting a calandria tube into a nuclear reactor. The method includes engaging the inner surface of the calandria tube with an insertion tool, inserting a portion of the calandria tube using the insertion tool through the first calandria tube seat bore, and guiding the guiding tool into the inner diameter of the calandria tube. inserting, and guiding a portion of the calandria tube through the second calandria tube seat bore via the insertion tool and the guiding tool.

The invention also provides an apparatus for positioning a calandria tube relative to a first calandria tube sheet bore and a second calandria tube sheet bore of a nuclear reactor. The device includes a work table mounted on a tube replacement platform positioned adjacent to the reactor, an insertion tool mounted on the work table and capable of engaging the inner diameter of the calandria tube through the first calandria tube seat bore, and a second calandria tube seat bore. It includes a guiding tool capable of engaging the inner diameter of the calandria tube through the calandria tube seat bore.

The present invention provides a method comprising removing a first calandria tube from a calandria tube bore via an insertion/removal tool and inserting a second calandria tube into the calandria tube bore via an insertion/removal tool. do.

Other aspects of the invention will become apparent upon consideration of the detailed description and accompanying drawings.

Various aspects of the invention will become apparent upon consideration of the detailed description and accompanying drawings.
1 is a perspective view of the reactor core of a nuclear reactor.
2 is a partially cutaway view of the fuel channel assembly.
Figure 3 is a schematic diagram of an insertion tool and a plurality of support members for a calandria tube.
Figure 4 is a schematic diagram of the insertion tool and calandria tube of Figure 3;
Figure 5 is a schematic diagram of the insertion tool of Figure 4 and the calandria tube and guide tool.
Figure 6 is a schematic diagram of an insertion tool and calandria tube and an alternative guidance tool.
Figure 7 is a schematic diagram of an insertion tool and calandria tube and other alternative guiding tools.
Figure 8A is a schematic diagram of an insertion tool and calandria tube and another alternative guidance tool.
Figure 8b is a front view of the guidance tool shown in Figure 8a.

Before describing embodiments of the present invention in detail, it will be understood that the present invention, in its application, is not limited to the structural details and arrangement of components shown in the following description or shown in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways.

1 is a perspective view of the reactor core of a CANDU ^TM type reactor 6, e.g. a 900 MW CANDU ^TM reactor. Alternatively, reactor 6 may be a 100-300MW CANDU ^™ reactor, a 600MW CANDU ^™ reactor, a 1000MW CANDU ^™ reactor, or another pressurized heavy water reactor (PHWR). The reactor core is typically contained inside a vault that is sealed with an air lock for radiation control and shielding. Although aspects of the invention are described for convenience with particular reference to a CANDU ^TM type reactor 6, the invention is not limited to CANDU ^TM type reactors and may be used outside of this specific field. Referring back to Figure 1, a generally cylindrical vessel (known as calandria 10 of CANDU ^™ type reactor 6) contains a heavy-water moderator. Calandria 10 has an annular shell 14 and tubular sheets 18 at first end 22 and second end 24. The tubular sheet 18 includes a plurality of holes (herein referred to as bores) each receiving a fuel channel assembly 28. As shown in FIG. 1 , a plurality of fuel channel assemblies 28 pass through the tubular sheet 18 of calandria 10 from first end 22 to second end 24 .

In some embodiments, such as the depicted embodiment, the reactor core has two walls at each end 22, 24 of the reactor core, namely tubular sheets 18 at each end 22, 24 of the reactor core. An inner wall 64 (often referred to as an “end shield”) is provided, which is positioned outwardly from the tube sheets 18 at each end 22, 24 of the reactor core. A grid tube 65 spans the distance between the tube sheet 18 and the end shield 64 in each pair of bores (i.e., in the tube sheet 18 and the end shield 64, respectively).

FIG. 2 is a partial cutaway view of one fuel channel assembly 28 of the reactor core shown in FIG. 1 . As shown in FIG. 2 , each fuel channel assembly 28 includes a calandria tube (“CT”) 32 that surrounds the other components of the fuel channel assembly 28 . Each CT 32 spans the distance between tube sheets 18 . Additionally, both ends of each CT 32 are received within and sealed against each bore 19 in the tube sheet 18. In some embodiments, a CT rolled joint insert 34 is used to secure the CT 32 to the tubular seat 18 within the bore. A pressure tube (“PT”) 36 forms the inner wall of the fuel channel assembly 28. PT 36 provides conduit for the reactor coolant and fuel bundle or assembly 40. PT 36 typically holds two or more fuel assemblies 40, for example, and also acts as a conduit for reactor coolant passing through each fuel assembly 40. An annular space 44 is formed between each PT 36 and its corresponding CT 32. This annular space 44 is typically filled with a circulating gas such as dry carbon dioxide, helium, nitrogen, air or mixtures thereof. One or more annular spacers or garter springs (48) are disposed between CT (32) and PT (36). The annular spacer 48 maintains a gap between the PT 36 and the corresponding CT 32 while allowing the annular gas to pass through and around the annular spacer 48.

As also shown in Figure 2, each end of each fuel channel assembly 28 is provided with an end accessory assembly 50, which is located outside the corresponding tube sheet 18. Each end appendage assembly 50 includes an end appendage body 57 and an end appendage liner 59. At the distal end of each end accessory assembly 50 is a closing plug 52. Each end accessory assembly 50 also includes a feeder assembly 54. This feeder assembly 54 supplies reactor coolant into or removes reactor coolant from PT 36 through feeder tube 59 (FIG. 1). In particular, for a single fuel channel assembly 28, the feeder assembly 54 at one end of the fuel channel assembly 28 acts as an inlet feeder, and the feeder assembly 54 at the opposite end of the fuel channel assembly 28 ) acts as an outlet feeder. As shown in Figure 2, feeder assembly 54 may be attached to end accessory assembly 50 using a connection assembly 56 that includes a plurality of screws, washers, seals and/or other types of connectors. there is. A grid tube (65) (as described above) encloses the connection between the end accessory assembly (50) and the PT (36) containing the fuel assembly (40). Shielding ball bearings 66 and coolant surround the exterior of the grid tube 65, thereby providing additional radiation shielding.

Referring back to Figure 2, positioning hardware assembly 60 and bellows 62 are also connected to each end accessory assembly 50. The bellows 62 allows the fuel channel assembly 28 to move axially, which may be important if the length of the fuel channel assembly 28 changes over time, which is common in many nuclear reactors. It is an ability that can be done. The positioning hardware assembly 60 can be used to position the end of the fuel channel assembly 28 in a locked or unlocked state that secures its axial position. Positioning hardware assembly 60 is also connected to end shield 64. Each of the illustrated positioning hardware assemblies 60 includes a rod having an end received in a bore of a respective end shield 64. In some embodiments, the rod end and bores in end shield 64 are threaded. Likewise, although a CANDU ^™ type reactor is shown in Figures 1 and 2, it should be understood that the present invention can be applied to other types of reactors, including reactors having similar components to those shown in Figures 1 and 2.

Figure 3 shows an insertion tool 110 for inserting calandria tube 32 into the calandria tube bore of tube sheet 18 (Figures 1, 4). Specifically, this insertion tool 110 is inserted into the bore of the first tube sheet 18 (on the first side of the reactor 6) and the second tube sheet 18 (on the reactor 6 opposite the first side). Insert the calandria tube (32) through the bore of ) on the second side of ). As shown, the insertion tool 110 includes a telescoping ram (118) including a first support 112, a second support 114, a telescoping arm 116, and a mounting portion 118. ram), and the mounting portion is for mounting the insertion tool 110 on the work table 100 on a tube replacement platform located adjacent to the reactor 6.

The first support part 112 and the second support part 114 are spaced apart from each other. The first support portion 112 and the second support portion 114 are mounted on the flexible arm 116 at a distance from each other, and as shown in FIG. 4, are coupled to the inner surface of the calandria tube 32 simultaneously. Consists of. The supports 112, 114 are schematically shown as being cylindrical, but may also be spoked or otherwise designed to engage with and support the calandria tube 32. A cantilevered support system is provided by using two separate supports 112, 114 such that when one end 22 of the calandria tube 32 is mounted on the tool 110, the calandria tube 32 )'s rotational moment is reduced.

The flexible arm 116 is configured to extend and retract along the longitudinal axis 120. The longitudinal axis 120 is aligned or parallel with the longitudinal axis of the calandria tube 32, such that extension of the telescoping arm 116 extends the calandria tube 32 along its axis and also extends the telescoping arm 116 along its axis. Retraction of the arm 116 retracts the calandria tube 32 along its axis. The flexible arm 116 is fixed to the mounting portion 118. Mounting portion 118 is movable along work table 100 so that insertion tool 110 can be aligned with various points along the reactor face. Specifically, the insertion tool 110 can be moved to align the telescoping arm with the bore in the first tubular seat 18.

3 and 4, the work table 100 further supports a plurality of support members 124. As shown, the support members 124 are spaced apart from each other along the length of the calandria tube 32. Four support members 124 are shown, but more or fewer support members (e.g., 1 to 3 support members, 5 + support members) are used to support the calandria tube 32 radially ( i.e. providing a force in the radial direction of the calandria tube 32) can also further reduce the moment of the cantilever tube 32 and the resulting deflection of the distal end 24 of the tube 32. Support member 124 may apply force to the outer surface of calandria tube 32. As shown in FIG. 4 , the support members 124 may apply force spaced apart from each other in the longitudinal direction of the calandria tube 32 . Support member 124 may be, for example, a hydraulically controlled plunger, a pneumatically controlled plunger, or an electrically controlled solenoid.

As shown in FIGS. 5 to 8B, guiding tools 130A to 13D are further provided to control the movement of the calandria tube 32. As shown in Figure 5, guiding tool 130A extends into one end of calandria tube 32. Specifically, the guiding tool 130 extends into the second end 24 of the calandria tube 32 opposite the first end 22 through which the insertion tool 110 extends. The guiding tool 130A, shown in Figure 5, is a cylindrical rod 132 that contacts the inner surface of the calandria tube 32 and includes a tapered end to improve the accuracy of insertion.

At least the second end 24 of the calandria tube 32 is a bell-shaped end and has a larger diameter than the diameter of the remainder of the tube 32. Guide tool 130B, shown in Figure 6, is a cylindrical rod, but unlike guide tool 130A, guide tool 130B has a larger end for engaging the bell-shaped end 24 of calandria tube 32. It's over. The larger end of guidance tool 130B may be tapered (as shown) to improve accuracy of insertion. The guiding tool 130B, when engaged with the bell-shaped end 24, is axially aligned with the second end 24 of the calandria tube 32.

As shown in Figure 7, the guiding tool 130C is provided with fingers 134 extending radially from the cylindrical body 132 to engage the inner surface of the calandria tube 32. As shown, the fingers 134 are offset from each other by 90 degrees, but this can be increased or decreased based on the density of the fingers 134. The fingers may be made of an elastic material to assist in off-center insertion of the guiding tool 130C into the calandria tube 32 and yet provide structural support to guide the calandria tube 32. ) can be maintained relative to the cylindrical body 132.

8A and 8B, guide tool 130D is provided with a cam 136 secured to the distal end of cylindrical body 132. Cam 136 has an oval profile 138 (FIG. 8B) and is mounted eccentrically relative to cylindrical body 132. Therefore, when the cam 136 is inserted into the end 24 of the calandria tube 32, the position of the end 24 of the calandria tube 32 changes due to rotation of the cylindrical body 132.

To replace the calandria tube (32), the old calandria tube (32) is removed and the bores of the first and second tube sheets (18) are prepared for the new calandria tube (32). The insertion tool 110 is moved along the support platform to align the telescoping arm 116 with the prepared bore in the first tubular seat 18. Once the insertion tool 110 is aligned, it is provided with a new calandria tube 32. The supports 112, 114 of the insertion tool 110 are inserted into the first end 22 of the calandria tube 32 and engage the inner surface of the tube 32, supporting the tube in a cantilevered manner. The telescoping arm 116 is extended to insert the second end 24 of the calandria tube 32 into the bore of the first tube sheet 18. To further support the tube 32, a support member 124 extends to radially support the tube 32 from below. The support member is provided with a distance sensor (for example, to support the bell-shaped end 24 in one actuation displacement and to support the center of the tube 32 in another actuation displacement) to determine the exact actuation distance. (not shown) can be used. With the alignment and support mentioned above in place, the second end 24 of the calandria tube 32 is inserted through the bore of the first tube sheet 18.

As the calandria tube 32 moves through the bore of the first tube sheet 18, the second end 24 begins to sag, moving out of alignment with the bore of the second tube sheet 18. Once the second end 24 of the calandria tube 32 is at a predetermined distance from the second tube sheet 18, the guiding tools 130A to 130D are inserted through the bore of the second tube sheet 18 to guide the calandria tube 32. It is combined with the second end (24) of the dry pipe (32). More specifically, the guiding tool 130 extends into the second end 24 of the calandria tube 32 and engages the inner surface of the calandria tube 32. The guiding tools 130A-130D prevent further sagging of the calandria tube 32 between the two tube sheets 18 and also align the tube 32 with the destination bore of the second tube sheet 18. In cases where the bore of the first tube sheet 18 is not perfectly aligned with the bore of the second tube sheet 18, the guiding tools 130A-130D may also guide the calandria tube 32 to the second tube sheet 18. ) serves to align it with the bore.

With the guiding tools 130A-130D engaged with the inner surface of the tube 132, the insertion tool 110 continues to push the second end 24 toward the bore of the second tube sheet 18. Some guidance tools (e.g., guidance tool 130C) may provide additional pulling force to assist the pushing force of insertion tool 110. As the second end 24 approaches the bore of the second tube seat 18, adjustment to the position of the second end 24 of the tube 32 occurs based on the output of a sensor (e.g., a position sensor, etc.). This can be done in response by the guidance tools 130A to 130D. For example, guiding tool 130D can be rotated to rotate cam 136 relative to tube 32, thereby modifying the position of calandria tube 32 relative to the bore of tube sheet 18.

Once second end 24 has safely passed the second bore, additional sensors (not shown) verify that tube 32 is fully inserted and properly positioned. Once calandria tube 32 is properly positioned, guide tool 130 and insertion tool 110 are separated and removed from the inner surface of tube 32. The insertion tool 110 is moved to a new location along the work table 100 to insert the calandria tube 32 into another bore.

The above system is provided with a control system and a plurality of sensors that provide feedback regarding the position of the calandria tube 32. Therefore, the process can be automated, allowing tubes 32 to be installed without direct user contact, thereby limiting human exposure around the reactor. Additionally, when the process is repeated for all calandria tubes 32 (tens to hundreds of tubes 32 per reactor 6), the control system uses information collected from previous tube installations to ensure that each completed insertion Later on, for example, necessary corrections to the insertion angle of the tube 32 can be anticipated and thus improve efficiency. Alternatively, the process described above may be completed through human interaction to operate insertion tool 110 and guidance tools 130A-130D.

It should be noted that the embodiments described above and shown in the accompanying drawings are given by way of example only and are not intended to limit the concepts and principles of the present invention. Accordingly, those skilled in the art will appreciate that various changes can be made in the elements and their configuration and arrangement without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims (16)

A method of removing a calandria tube from a nuclear reactor, comprising:
Inserting a removal tool into the calandria tube through a first calandria tube seat bore, the removal tool comprising a plurality of spaced apart supports located along the length of the inner surface of the calandria tube;
Combining the plurality of spaced-apart supports with the inner surface of the calandria tube at a plurality of points spaced apart along the length of the inner surface of the calandria tube;
moving the calandria tube from the second calandria tube seat bore with the removal tool; and
guiding the calandria tube through the first calandria tube seat bore as the removal tool draws the calandria tube.
How to remove the calandria tube from the reactor. According to paragraph 1,
inserting a guiding tool into the calandria tube through the second calandria tube sheet bore to engage the inner surface of the calandria tube with a guiding tool; and
When the removal tool pulls the calandria tube, using the guiding tool to guide the calandria tube through the first calandria tube seat bore. According to paragraph 1,
The calandria tube is inserted longitudinally through a first calandria sheet bore and a second calandria sheet bore, and further comprising supporting the outer surface of the calandria tube in a radial direction perpendicular to the longitudinal direction, method. According to paragraph 2,
The step of guiding the calandria tube through the first calandria tube sheet bore,
axially displacing the calandria tube using the removal tool, and
Aligning a tailing end of the calandria tube with the second calandria tube sheet bore. According to paragraph 4,
Wherein aligning the distal end of the calandria tube with the second calandria tube sheet bore further comprises displacing the guiding tool. According to paragraph 4,
Wherein aligning the distal end of the calandria tube with the second calandria tube sheet bore further comprises rotating the guiding tool relative to a removal direction. According to paragraph 2,
The step of guiding a portion of the calandria tube through the second calandria tube sheet bore,
pulling the calandria tube using the removal tool; and
A method comprising pushing the calandria tube using the guiding tool. According to paragraph 1,
The method further comprising mounting the removal tool to a platform adjacent the reactor. According to paragraph 2,
The method of claim 1 , wherein the guiding tool is engaged with the inner surface of the calandria tube after a portion of the calandria tube is removed through the first calandria tube seat bore. A device for removing calandria tubes from a first calandria tube sheet bore and a second calandria tube sheet bore of a nuclear reactor, comprising:
a removal tool capable of engaging the inner surface of the calandria tube through the first calandria tube seat bore;
an insertion tool comprising an arm coupled to a plurality of axially spaced supports for positioning along the length of the inner surface of the calandria tube, and
An arm extending axially into the calandria tube and configured to move the calandria tube toward the second calandria tube seat bore when a plurality of axially spaced supports are positioned along the length of the inner surface of the calandria tube. Device, including. 11. The device of claim 10, comprising a guiding tool that can be coupled to an inner surface of the calandria tube through the second calandria tube seat bore. According to clause 10,
The device of claim 1, wherein the removal tool includes a telescoping ram. According to clause 10,
The plurality of axially spaced supports of the insertion tool include a first support portion and a second support portion axially spaced from the first support portion, wherein the first support portion and the second support portion are of the calandria tube. A device capable of engaging the inner surface of the calandria tube between opposing bell-shaped ends. According to clause 10,
The device further comprising a plurality of support members capable of engaging an outer surface of the calandria tube. According to clause 14,
The apparatus of claim 1, wherein the plurality of support members are hydraulically controlled plungers, pneumatically controlled plungers, or electrically controlled solenoids. According to clause 11,
The removal tool may engage a first end of the calandria tube and the guiding tool may engage a second end of the calandria tube, the second end being opposite the first end. Device.