JP2015102527A - Nuclear reactor pressure vessel maintenance device and nuclear reactor pressure vessel maintenance method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle maintenance device capable of inspecting and repairing corners of a water supply nozzle the curvature shape of which changes three-dimensionally while avoiding a water supply sparger constituted by a T-pipe arranged in a front and an annular header pipe, even if the corners of the water supply nozzle are difficult to access.SOLUTION: A nozzle maintenance device includes: a maintenance tool 28 inspecting and repairing corners of a water supply nozzle a pipe of which is present along a reactor wall of a reactor pressure vessel; an offset arm 25 supporting the maintenance tool 28 on a tip end thereof, and setting the maintenance tool 28 to each corner of the watery supply nozzle while avoiding the pipe present along the reactor wall of the reactor pressure vessel; and a driving unit 26 arranged in a reactor inner side of the pipe present along the reactor wall of the reactor pressure vessel, and driving the offset arm 25 to operate.

Description

  The present invention relates to a reactor pressure vessel nozzle maintenance apparatus and maintenance method thereof, and more particularly to an atom suitable for efficiently inspecting and repairing the surface of a corner portion of a reactor pressure vessel nozzle during a service period of a nuclear power plant. The present invention relates to a furnace pressure vessel nozzle maintenance device and a maintenance method thereof.

  In general, a water supply nozzle of a reactor pressure vessel (hereinafter referred to as RPV) has a water supply sparger composed of a T-shaped tube welded to a thermal sleeve and an annular header pipe connected to the T-shaped tube. In addition, since the core spray pipe is arranged close to the lower part, accessibility to the relevant part when checking and repairing the corner part of the water supply nozzle is obstructed.

  Moreover, the wall surface of the RPV and the annular header are installed with a predetermined size, the gap is very narrow as several tens of millimeters, and a thermal sleeve exists in the axial direction of the RPV nozzle from the T-shaped tube. The space is narrow and there is very little space for inspection and repair work.

  As an apparatus for inspecting a member located in such a narrow space of RPV, for example, there are apparatuses described in Patent Documents 1 and 2.

  Patent Document 1 describes a nondestructive inspection device used for inspection of a thermal sleeve weld in an RPV nozzle. The structure has a tape probe fixed to the core spray pipe and moving the scanner section in the axial direction, and a guide rail that moves the tape probe in the circumferential direction, and is formed by the inside of the RPV nozzle and the outside of the thermal sleeve. The scanner portion is moved in the axial direction by a tape probe similar to a tape measure for accessing a circumferential narrow space, and the thermal sleeve welded portion is accessed. And the scanner part which reached | attained the thermal sleeve welding part test | inspects the welding part located in the circumferential shape by carrying out the turning operation | movement to the circumferential direction along a guide rail.

  On the other hand, what is described in Patent Document 2 is a double tube structure flaw detection device for flaw detection of a welded portion located in a gap between an outer tube and an inner tube among double tube structures. . The structure includes a flaw detection head that accesses the gap between the RIP casing and the RPV in which the RIP nozzle is installed, and a rotating ring that rotates the arm in the circumferential direction. The welded portion between the RIP casing and the RIP nozzle is circular. It is for flaw detection.

Japanese Patent No. 4910715 Japanese Patent No. 2760712

  As described above, the corner portion of the RPV nozzle has an annular header pipe connected to the T-shaped tube on the front surface thereof, and a core spray pipe is disposed below it, so that the accessibility is extremely poor. . In addition, since the corner portion of the RPV nozzle is a through-hole orthogonal to the cylindrical RPV wall surface and the intersection is chamfered with a small curvature, the cross-sectional shape of the corner portion of the RPV nozzle is a circumference. It has a three-dimensional shape that is not uniform and changes according to the angle.

  However, in Patent Document 1 described above, since the welded portion of the thermal sleeve is targeted, the narrowness of the gap between the corner portion of the RPV nozzle and the annular header pipe is not considered, so the scanner portion is accessed to the narrow portion. Can not do it. Moreover, since the core spray piping is targeted, it is not assumed that there is another piping below. Therefore, when the water supply nozzle is targeted, the semicircular lower guide rail interferes with the core spray piping, and the apparatus cannot be set. Furthermore, since the shape of the welded portion of the thermal sleeve is a two-dimensional curve located on the cylindrical surface, it can be handled by turning the tape probe on the circumference. Since the cross-sectional shape changes three-dimensionally, the conventional technique cannot follow the shape.

  On the other hand, in patent document 2 mentioned above, since the obstacle equivalent to the water supply sparger located in front of the RPV nozzle is not taken into consideration, the apparatus cannot access the flaw detection position. Moreover, since the shape of the welded portion between the RIP casing, which is the flaw detection site, and the RIP nozzle is a two-dimensional curve located on the cylindrical surface, the cross-sectional shape of the corner changes as in Patent Document 1. It cannot be applied to the corner of the water supply nozzle.

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is constituted by a T-shaped pipe disposed on the front surface and an annular header pipe even in a corner portion of a water supply nozzle having poor accessibility. An object of the present invention is to provide a reactor pressure vessel nozzle maintenance device and a maintenance method thereof capable of avoiding a feed water sparger and inspecting and repairing a corner portion of a feed water nozzle whose curvature shape changes three-dimensionally.

  In order to achieve the above object, a maintenance device for a reactor pressure vessel nozzle according to the present invention includes a maintenance tool for inspecting and repairing a corner portion of a water supply nozzle where piping is present along a reactor wall of the reactor pressure vessel, and the maintenance tool. An offset arm that supports the tool at the tip and avoids piping existing along the reactor wall of the reactor pressure vessel and sets the maintenance tool at the corner of the water supply nozzle; and the reactor pressure vessel And a drive unit that operates the offset arm and is disposed inside the furnace of a pipe existing along the furnace wall.

  Further, in order to achieve the above object, the maintenance method for a reactor pressure vessel nozzle according to the present invention is configured to inspect and repair a corner portion of a water supply nozzle where piping exists along the reactor wall of the reactor pressure vessel. A maintenance tool fixed to the tip of the offset arm is set at the corner of the water supply nozzle while avoiding piping existing along the furnace wall of the reactor pressure vessel, and along the reactor wall of the reactor pressure vessel The corner portion of the water supply nozzle is inspected and repaired by operating the offset arm with a driving unit disposed inside the furnace of the existing pipe.

  According to the present invention, even in a corner portion of a water supply nozzle having poor accessibility, a water supply sparger composed of a T-shaped pipe and an annular header pipe arranged on the front surface is avoided, and the curvature shape is changed three-dimensionally. You can check and repair the corner of the water nozzle.

It is a figure which shows schematic structure of RPV with which Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of this invention is applied. It is a fragmentary sectional view which shows the structure of the water supply nozzle and water supply sparger in RPV to which Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of the present invention is applied. It is the figure which looked at Fig.2 (a) from the arrow P direction. It is a figure explaining the cross-sectional change of the corner part of the water supply nozzle in RPV to which Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of the present invention is applied. It is a perspective view which shows the single offset arm inspection apparatus employ | adopted as the maintenance apparatus of the reactor pressure vessel nozzle of this invention. It is a perspective view which shows the double offset arm inspection apparatus employ | adopted as Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of this invention. The procedure of the maintenance method of the reactor pressure vessel nozzle by the double offset arm inspection apparatus employ | adopted as Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of this invention is shown, and it is a perspective view of the initial state of a double offset arm inspection apparatus. is there. It is a perspective view which shows the state which slid the drive part forward with the front-back axis | shaft from the state of FIG. 6, and pressed the flaw detection probe above the corner part of the water supply nozzle. FIG. 8 is a perspective view showing a state in which the corner portion on the back side of the water supply sparger is inspected with a flaw detection probe by the second-stage offset by turning the double offset arm to the right from the state of FIG. It is sectional drawing which shows the division | segmentation corresponding to the access of the double offset arm to the corner part upper side of the water supply nozzle in RPV to which Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of the present invention is applied. It is sectional drawing which shows the division | segmentation corresponding to the access of the double offset arm to the corner part lower side of the water supply nozzle in RPV to which Example 1 of the maintenance apparatus of the reactor pressure vessel nozzle of the present invention is applied. 1 shows an example of a structure of a flaw detection probe fixed to the tip of a double offset arm employed in a first embodiment of a reactor pressure vessel nozzle maintenance apparatus of the present invention, and has a shape combining an RPV inner diameter and a corner curvature. It is a fragmentary sectional view in the state where the flaw detection sensor was pressed in a shape slightly opened along. 1 shows an example of a structure of a flaw detection probe fixed to the tip of a double offset arm employed in a first embodiment of a reactor pressure vessel nozzle maintenance apparatus of the present invention, and has a shape combining an RPV inner diameter and a corner curvature. It is a fragmentary sectional view in the state where a flaw detection sensor was pressed in the shape closed a little along. Another example of the structure of a flaw detection probe fixed to the tip of a double offset arm, which is a second embodiment of the reactor pressure vessel nozzle maintenance apparatus of the present invention, is shown in a shape combining the RPV inner diameter and the corner curvature. It is a fragmentary sectional view in the state where the flaw detection sensor was pressed in a shape slightly opened along. Another example of the structure of a flaw detection probe fixed to the tip of a double offset arm, which is a second embodiment of the reactor pressure vessel nozzle maintenance apparatus of the present invention, is shown in a shape combining the RPV inner diameter and the corner curvature. It is a fragmentary sectional view in the state where a flaw detection sensor was pressed in the shape closed a little along. Another example of the structure of a flaw detection probe fixed to the tip of a double offset arm, which is a third embodiment of the reactor pressure vessel nozzle maintenance apparatus of the present invention, is shown in a shape combining the RPV inner diameter and the corner curvature. It is a fragmentary sectional view in the state where the flaw detection sensor was pressed in a shape slightly opened along. Another example of the structure of a flaw detection probe fixed to the tip of a double offset arm, which is a third embodiment of the reactor pressure vessel nozzle maintenance apparatus of the present invention, is shown in a shape combining the RPV inner diameter and the corner curvature. It is a fragmentary sectional view in the state where a flaw detection sensor was pressed in the shape closed a little along. It is Example 4 of the maintenance apparatus of the reactor pressure vessel nozzle of this invention, and is a perspective view which shows the grinding | polishing apparatus employ | adopted as a maintenance apparatus. It is a figure which shows the operation | movement structure of the grindstone 39 in the grinding | polishing apparatus 38 shown in FIG. It is a flowchart which shows the maintenance method of the reactor pressure vessel nozzle which is Example 5 of this invention.

  The reactor pressure vessel nozzle maintenance apparatus and maintenance method of the present invention will be described below based on the illustrated embodiments. In addition, in each Example, the same code | symbol is used for the same component.

  FIG. 1 shows a schematic configuration of an RPV to which Example 1 of the reactor pressure vessel nozzle maintenance apparatus of the present invention is applied.

  As shown in the figure, a shroud 2 and an upper lattice plate 3 and a core support plate 4 are arranged vertically inside the shroud 2 inside the RPV 1. In addition, a core spray purger 5 is installed on the upper part of the shroud 2 and is connected to a core spray pipe 7 coming out of the core spray nozzle 6 above the shroud 2. A water supply nozzle 8 is positioned above the core spray nozzle 6 and a water supply sparger 9 is disposed on the inner wall surface of the RPV 1.

  FIG. 2A and FIG. 2B show the structures of the water supply nozzle 8 and the water supply sparger 9. In the figure, the water supply nozzles 8 are arranged at equal intervals around the circumference of the RPV 1, penetrate the wall surface of the RPV 1, and the corner portion 10 is chamfered with a curved shape. On the other hand, the water supply sparger 9 has a T-shaped pipe 12 fixed to the tip of a thermal sleeve 11 located inside the water supply nozzle 8 and annular header pipes 13 connected to both ends of the T-shaped pipe 12. A large number of spray nozzles 14 are arranged on the upper surface of the header pipe 13.

  Both end portions of the water supply sparger 9 are fixed along the inner wall surface of the RPV 1 by brackets 1A attached to the inner wall surface of the RPV 1, but at this time, the gap g between the water supply sparger 9 and the inner wall surface of the RPV 1 is It is extremely narrow, about several tens of millimeters. The core spray nozzle 6 is positioned below the feed water sparger 9 (see FIG. 1), the core spray pipe 7 is positioned annularly along the inner wall surface of the RPV 1, and the pipe extending downward at the end is the core. It is connected to the place purger 5 (see FIG. 1).

  At this time, the gap G between the water supply sparger 9 and the core spray pipe 7 is close to about 200 mm (see FIG. 2B). For this reason, in order to approach the corner part 10 of the water supply nozzle 8, since the water supply sparger 9 is located in the front (direction of Fig.2 (a)) and the core spray piping 7 is located below, It is necessary to avoid it. Further, a thermal sleeve 11 and a T-shaped tube 12 are welded and fixed inside the water supply nozzle 8 via a taper tube 15, and a space accessible to the corner portion 10 of the water supply nozzle 8 is a T-shaped tube 12. And only a slight gap located on the outer periphery of the taper tube 15.

  Next, the cross-sectional change of the corner part 10 of the water supply nozzle 8 is demonstrated using FIG. In FIG. 3, since the water supply nozzle 8 penetrates the inner wall surface of the cylindrical RPV 1, the cross section (the cross section (a)-(a) in FIG. 3) of the corner portion 10 of the water supply nozzle 8 viewed in the horizontal plane of the RPV 1 is The shape is a combination of the inner diameter of the RPV 1 and the curvature of the corner portion 10 perpendicular to the inner diameter (see FIG. 3A). Moreover, the cross section (the (c)-(c) cross section of FIG. 3) of the corner part 10 of the water supply nozzle 8 seen in the longitudinal section of RPV1 is the longitudinal section of the cylindrical RPV1 and the curvature of the corner part 10 orthogonal thereto. It becomes a combined shape (see (c) of FIG. 3), and the cross-sectional shape is different. The cross section at the intermediate angle (cross section (b)-(b) in FIG. 3) has a cross-sectional shape formed with a curvature connecting the horizontal plane and the vertical cross section (see FIG. 3 (b)), and the water supply nozzle When inspection and repair are performed along the outer periphery of the corner portion 10, it is necessary to take measures corresponding to the curvature of the cross section that changes depending on the angle.

  A first embodiment of a reactor pressure vessel nozzle maintenance device applied to the corner portion 10 of the water supply nozzle 8 located in the narrow portion as described above will be described with reference to FIGS. 4 and 5.

  The reactor pressure vessel nozzle maintenance device of this embodiment shown in FIGS. 4 and 5 shows a single offset arm inspection device 16 and a double offset arm inspection device 24 for the purpose of flaw detection of the corner portion 10 of the water supply nozzle 8, respectively. .

  As shown in FIGS. 4 and 5, the single offset arm inspection device 16 and the double offset arm inspection device 24 are set on the surface of the corner portion 10 of the water supply nozzle 8 as a maintenance tool and inspect the corner portion 10. And 28, the single offset arm 18 and the double offset arm 25 for setting the flaw detection probes 17 and 28 at arbitrary positions of the corner portion 10 of the water supply nozzle 8, and the single offset arm 18 and the double offset arm 25 are connected to the water supply nozzle 8 The drive units 19 and 26 that perform the turning and / or back-and-forth movement in accordance with the outer periphery of the corner portion 10, the bases 20 and 30 that support the drive units 19 and 26, and the bases 20 and 30 are configured integrally. Single offset arm inspection device on T-tube 12 of sparger 9 And a fixed portion 21 and 31 for setting the double offset arm inspection device 24.

  The single offset arm 18 shown in FIG. 4 is offset in one direction (one place) with respect to the axial center (D in FIG. 4) of the drive unit 19, that is, the first-stage offset arm 18 a from the axial direction of the drive unit 19. Is offset by extending in the radial direction, and a second-stage offset arm 18b is extended in the axial direction from the tip of the first-stage offset arm 18a, and the flaw detection probe 17 is provided at the tip of the second-stage offset arm 18b. Is extended and fixed in the axial direction.

  On the other hand, in the double offset arm 25 shown in FIG. 5, the arm offset in one direction with respect to the axial center (D in FIG. 5) of the drive unit 26 is further offset in the circumferential direction of the corner portion 10 of the water supply nozzle 8. That is, the first-stage offset arm 25a extends in the radial direction from the axial direction of the drive unit 26 and is offset, and the second-stage offset arm 25b extends in the axial direction from the tip of the first-stage offset arm 25a. A third-stage offset arm 25c extends in the circumferential direction from the tip of the second-stage offset arm 25b and further offset, and a flaw detection probe 28 extends in the axial direction and is fixed to the tip of the third-stage offset arm 25c. Yes.

  And the single offset arm inspection apparatus 16 shown in FIG. 4 respond | corresponds to the site | part of the upper and lower side where the single offset arm 18 does not produce interference with the water supply sparger 9 among the corner 10 parts of the water supply nozzle 8. When the reference of the single offset arm 18 connected to the drive unit 19 is positioned on the center of the water supply nozzle 8, the water supply sparger 9 is avoided by the offset, and the flaw detection probe 17 is set at the corner portion 10 of the water supply nozzle 8. The drive unit 19 has a swivel shaft (not shown) for driving the single offset arm 18 in the swivel direction 22 along the corner portion 10 of the water supply nozzle 8, and a single offset arm for pressing the flaw detection probe 17 against the water supply nozzle 8. It has a longitudinal axis (not shown) for driving 18 in the longitudinal direction 23.

  A turning shaft for driving the single offset arm 18 in the turning direction 22 along the corner portion 10 of the water supply nozzle 8 is operated by a motor and a speed reducer (not shown) built in the drive portion 19, and the flaw detection probe 17 is moved. The front / rear shaft that drives the single offset arm 18 in the front / rear direction 23 to press the water supply nozzle 8 is operated by a slide mechanism (not shown) that moves the drive unit 19 along the base 20.

The fixing portion 21 includes two plate-like members 21a and 21b so as to sandwich the base 20 from both sides. The upper portions of the plate-like members 21a and 21b extend in the extending direction of the flaw detection probe 17, and A mold part 21c having a tip portion that follows the shape of the water supply sparger 9 is formed, and the lower portions of the respective plate-like members 21a and 21b extend in the extending direction of the flaw detection probe 17, and the tip portion thereof is a fixed portion 21. On the other hand, the double offset arm inspection device 24 shown in FIG. 5 has a double offset arm 25 with respect to the single offset arm 18 shown in FIG. The corner portion 1 of the water supply nozzle 8 is configured by adding an offset in the circumferential direction of the water supply nozzle 8 to the portion, and located on the back side of the water supply sparger 9. This corresponds to the left and right side portions of 0. The drive unit 26 has a swiveling shaft (not shown) that drives the double offset arm 25 in the swiveling direction 27 along the corner portion 10 of the water supply nozzle 8 and a double shaft for pressing the flaw detection probe 28 against the water supply nozzle 8. It has a longitudinal axis (not shown) for driving the offset arm 25 in the longitudinal direction 29.

  A turning shaft for driving the double offset arm 25 in the turning direction 27 along the corner portion 10 of the water supply nozzle 8 is operated by a motor and a speed reducer (not shown) built in the driving portion 26, and the flaw detection probe 28 is moved. The front / rear shaft that drives the double offset arm 25 in the front / rear direction 29 to press the water supply nozzle 8 is operated by a slide mechanism (not shown) that operates the drive unit 26 along the base 30.

  The fixing portion 31 includes two plate-like members 31a and 31b so as to sandwich the base 30 from both sides. The upper portions of the plate-like members 31a and 31b extend in the extending direction of the flaw detection probe 28, and A mold part 31c having a tip portion that follows the shape of the water supply sparger 9 is formed, and lower portions of the respective plate-like members 31a and 31b extend in the extending direction of the flaw detection probe 28, and the tip portion thereof is a fixed portion 31. A contact portion 31d for forcing the inclination is formed.

  The single offset arm inspection device 16 and the double offset arm inspection device 24 may share the drive units 19 and 26, the bases 20 and 30, and the fixing units 21 and 31 as a structure for exchanging arm portions.

  Next, the procedure of the maintenance method of the reactor pressure vessel nozzle by the double offset arm inspection device 24 will be described with reference to FIGS. In addition, the procedure of a present Example is a procedure in the case of corresponding to the right side of the corner part 10 of the water supply nozzle 8. FIG.

  First, as shown in FIG. 6, in the initial state, the drive unit 26 is located at the rear end of the base 30, and the double offset arm inspection device 24 is installed above the RPV 1 with the water supply sparger 9 and the tip of the double offset arm 25 not interfering with each other. Further, the mold-carrying part 31c of the plate-like members 31a and 31b is set to the water supply sparger 9 (see FIG. 6). Next, the double offset arm 25 is swung around the swivel axis to adjust the angle so as to avoid the water supply sparger 9, and then the drive unit 26 is slid forward along the front-rear shaft to detect flaws above the corner portion 10 of the water supply nozzle 8. The probe 28 is pressed (see FIG. 7). Next, the double offset arm 25 is turned to the right by the turning shaft, and the corner portion 10 on the back side of the water supply sparger 9 is inspected by the flaw detection probe 28 by the second stage offset (see FIG. 8).

  FIG. 9 and FIG. 10 show sections corresponding to access of the double offset arm 25 to the corner portion 10 of the water supply nozzle 8.

  In the figure, the upper side and the right side of the corner portion 10 of the water supply nozzle 8 correspond by avoiding the double offset arm 25 above the water supply sparger 9. The upper side of the corner portion 10 of the water supply nozzle 8 corresponds to the position of the first offset arm 25 a of the double offset arm 25, and the right side of the corner portion 10 of the water supply nozzle 8 is the second stage offset of the double offset arm 25. The correspondence at the position of the arm 25b is as described above.

  On the other hand, the lower side of the corner portion 10 of the water supply nozzle 8 is set by turning the turning shaft about the angle at which the offset direction of the first offset arm 25a of the double offset arm 25 is positioned downward, and the drive portion 26 is moved back and forth. It is slid forward by the shaft and set through a gap between the feed water sparger 9 and the core spray pipe 7. Thereafter, the swivel shaft is swung to inspect the lower side of the corner portion 10 of the water supply nozzle 8 with the flaw detection probe 28. Similarly, on the left side of the corner portion 10 of the water supply nozzle 8, a swiveling axis is set at an angle where the first offset direction of the double offset arm 25 is located downward, and the drive unit 26 is slid forward by the front and rear axes to supply water. It is set through a gap between the sparger 9 and the core spray pipe 7.

  At this time, the offset direction of the second stage of the double offset arm 25 is located on the left side of the corner portion 10 of the water supply nozzle 8. The left side can be inspected by the flaw detection probe 28.

  FIGS. 11 and 12 show an example of the structure of the flaw detection probe 28 fixed to the tip of the double offset arm 25 employed in this embodiment. As described above with reference to FIG. 3, the shape of the corner portion 10 of the water supply nozzle 8 changes three-dimensionally depending on the angle of the water supply nozzle 8. Therefore, the flaw detection probe 28 needs to have a structure for closely contacting the shape change of the corner portion 10.

  The flaw detection probe 28 employed in the present embodiment shown in FIGS. 11 and 12 is an example of a structure for pressing the flaw detection probe 28 with a mechanical spring 34. That is, the flaw detection probe 28 shown in the figure has a flaw detection sensor 32 set on the surface of the corner portion 10 of the water supply nozzle 8 for inspection, a shoe 33 for fixing the flaw detection sensor 32, and a flaw detection sensor fixed to the shoe 33. A mounting seat 35 for mounting 32 to the double offset arm 25, and a mechanical spring 34 supported by the mounting seat 35 and pressing the flaw detection sensor 32 against the corner portion 10 of the water supply nozzle 8.

  The above-described flaw detection sensor 32 is a film-like eddy current flaw detection sensor, which is fixed to a shoe 33 that is a resin having curvature and elasticity, and is pressed against the corner portion 10 of the water supply nozzle 8 via the shoe 33. The mechanical spring 34 always works in the direction in which the mechanical spring 34 is pressed against the corner portion 10 of the water supply nozzle 8. In the horizontal section of the corner portion 10 of the water supply nozzle 8, it is somewhat Inspection can be performed by pressing the flaw detection sensor 32 in an open shape (see FIG. 11). Further, in the longitudinal section of the corner portion 10 of the water supply nozzle 8, it can be inspected by pressing the flaw detection sensor 32 in a slightly closed shape along the shape combining the longitudinal section of the RPV 1 and the curvature of the corner portion 10 (see FIG. 12). ).

  According to the present embodiment, the structure having the double offset arm 25 and the flaw detection probe 32 that follows the curvature change of the corner portion 10 of the water supply nozzle 8 avoids the water supply sparger 9 and includes the back surface of the water supply sparger 9. Further, it is possible to carry out inspection (flaw detection inspection) of the entire periphery of the corner portion of the water supply nozzle 8 and to maintain the reactor pressure vessel nozzle.

  FIGS. 13 and 14 show another example of the structure of the flaw detection probe 28 fixed to the tip of the double offset arm 25 according to the second embodiment of the present invention, which is an example of a structure in which the flaw detection probe 28 is pressed by fluid pressure. .

  The flaw detection probe 28 employed in the present embodiment shown in FIGS. 13 and 14 includes a flaw detection sensor 32 that is set and inspected on the surface of the corner portion 10 of the water supply nozzle 8, and a shoe 33 that fixes the flaw detection sensor 32. A mounting seat 35 for attaching the flaw detection sensor 32 fixed to the shoe 33 to the double offset arm 25, and a tube 36 which is supported by the mounting seat 35 and presses the flaw detection sensor 32 to the corner portion 10 of the water supply nozzle 8 with fluid pressure. It is composed of

  The above-described flaw detection sensor 32 is a film-like eddy current flaw detection sensor, is fixed to a shoe 33 that is a resin having curvature and elasticity, and is pressed against the corner portion 10 of the water supply nozzle 8 via the shoe 33. The tube 36 has a direction in which both sides thereof are sandwiched and swelled by a rigid body (not shown) defined on the flaw detection sensor 32 side, and is always pressed against the corner portion 10 of the water supply nozzle 8 (FIGS. 13 and 14). In the E direction).

  The fluid pressure in the tube 36 may be either air pressure or water pressure. At this time, the horizontal cross section of the corner portion 10 of the water supply nozzle 8 can be inspected by pressing the flaw detection sensor 32 in a slightly open shape along the shape combining the inner diameter of the RPV 1 and the curvature of the corner portion 10 (see FIG. 13). ). Further, the longitudinal section of the corner portion 10 of the water supply nozzle 8 can be inspected by pressing the flaw detection sensor 32 in a slightly closed shape along the shape combining the longitudinal section of the RPV 1 and the curvature of the corner portion 10 (see FIG. 14). ).

  Even with the configuration of this embodiment, the effect is the same as that of the first embodiment.

  15 and 16 show still another example of the structure of the flaw detection probe 28 fixed to the tip of the double offset arm 25 according to the third embodiment of the present invention, which is an example of a structure in which the flaw detection probe 28 is pressed by an elastic body. is there.

  A flaw detection probe 28 employed in the present embodiment shown in FIGS. 15 and 16 includes a flaw detection sensor 32 that is set and inspected on the surface of the corner portion 10 of the water supply nozzle 8, and a shoe 33 that fixes the flaw detection sensor 32. A mounting seat 33 that attaches the flaw detection sensor 32 fixed to the shoe 33 to the double offset arm 25, and an elastic body 37 that is supported by the mounting seat 33 and presses the flaw detection sensor 32 against the corner portion 10 of the water supply nozzle 8. Has been.

  The above-described flaw detection sensor 32 is a film-like eddy current flaw detection sensor, is fixed to a shoe 33 that is a resin having curvature and elasticity, and is pressed against the corner 10 of the water supply nozzle 8 via the shoe 33. The elastic body 37 is sandwiched by rigid bodies (not shown) on both sides thereof, and the direction of the elastic reaction force is defined on the flaw detection sensor 32 side. By pressing the flaw detection sensor 32 against the corner portion 10 of the water supply nozzle 8, It has a structure that follows changes.

  Any elastic body 37 may be used as long as it has an elastic reaction force such as an elastic rubber or an elastic resin. At this time, the horizontal section of the corner portion 10 of the water supply nozzle 8 can be inspected by pressing the flaw detection sensor 32 in a slightly open shape along the shape combining the inner diameter of the RPV 1 and the curvature of the corner portion 10 (see FIG. 15). ). In addition, the longitudinal section of the corner portion 10 of the water supply nozzle 8 can be inspected by pressing the flaw detection sensor 32 in a slightly closed shape along the shape combining the longitudinal section of the RPV 1 and the curvature of the corner portion 10 (see FIG. 16). ).

  Even with the configuration of this embodiment, the effect is the same as that of the first embodiment.

  If a defect is found in the corner portion 10 by inspection of the corner portion 10 of the water supply nozzle 8 by the double offset arm inspection device 24 described above, the found defective portion is removed by surface polishing.

  FIG. 17 shows an example of a polishing apparatus 38 that removes defective portions found in the corner portion 10 of the water supply nozzle 8 by surface polishing as a fourth embodiment of the present invention.

  As shown in the figure, the polishing apparatus 38 of the present embodiment has a grindstone 39 set on the surface of the corner portion 10 of the water supply nozzle 8 for polishing, and the grindstone 39 at an arbitrary position of the corner portion 10 of the water supply nozzle 8. A double offset arm 41 to be set, a drive unit 42 that turns and / or moves back and forth in accordance with the outer periphery of the corner portion 10 of the water supply nozzle 8, a base 43 that supports the drive unit 42, and a base 43 And a fixing portion 44 that fixes the polishing device 38 to the T-shaped tube 12 of the water supply sparger 9 in the RPV 1.

  In place of the double offset arm 41, a single offset arm that is offset at one place can be used similarly to the single offset arm inspection device 16 described above.

  The double offset arm 41 in this embodiment avoids the water supply sparger 9 by the first-stage offset arm 41a, and the second-stage offset arm 41b extends in the axial direction from the tip of the first-stage offset arm 41a. Further, the third-stage offset arm 41c extends in the circumferential direction from the tip of the second-stage offset arm 41b and further offset, and the grindstone 39 extends in the axial direction and is fixed to the tip of the third-stage offset arm 41c. The back side of the water supply sparger 9 can be accessed by the third-stage offset arm 41c.

  Further, the drive unit 42 has a swivel shaft that drives the double offset arm 41 in the swivel direction 45 along the corner portion 10 of the water supply nozzle 8 and a double offset arm for pressing the grindstone 39 against the corner portion 10 of the water supply nozzle 8. 41 has a front-rear shaft for driving in the front-rear direction 46. The pivot axis is operated by a motor and a speed reducer (not shown) built in the drive unit 42, and the front and rear axes are operated by a slide mechanism (not shown) that moves the drive unit 42 along the base 43. To do.

  The fixing portion 44 is composed of two plate-like members 44a and 44b so as to sandwich the base 43 from both sides, and the upper portions of the plate-like members 44a and 44b extend in the extending direction of the grindstone 39, and the tip thereof A mold taking part 44c is formed along the shape of the water supply sparger 9, and the lower part of each plate-like member 44a, 44b extends in the extending direction of the grindstone 39, and its tip part is an inclination of the fixing part 44. An abutting portion 44d for forcing is formed.

  FIG. 18 shows an operational configuration of the grindstone 39 in the polishing apparatus 38 of the present embodiment. As shown in the figure, the polishing apparatus 38 of the present embodiment has a motor for a second-stage offset arm 41b disposed between the first-stage offset arm 41a and the third-stage offset arm 41c of the double offset arm 41. 47, a first gear 48 is provided at the tip of the motor 47, and a second gear 49 is provided at the base side of the grindstone 39, and between the first gear 48 and the second gear 49 is provided. By connecting with the transmission mechanism 50, the rotational force of the motor 47 can be transmitted to the grindstone 39. The transmission mechanism 50 is built in the offset arm 41c at the third stage, and may be any method such as a combination of tune, belt or gear.

  The polishing apparatus 38 according to the configuration of this embodiment can access an arbitrary position of the corner portion 10 of the water supply nozzle 8, and grindstone 39 against defects found in the corner portion 10 of the water supply nozzle 8. By setting, the defective portion can be removed by surface polishing.

  Next, details of the method for maintaining the reactor pressure vessel nozzle in this embodiment will be described with reference to FIG. The procedure shown in FIG. 19 will be described with a maintenance method for the water supply nozzle 8 as a representative example.

  As shown in the figure, in-furnace equipment located on the upper part of the shroud 2 such as a steam dryer (not shown) and a steam separator (not shown) installed on the RPV 1 is removed (S1), and the water supply nozzle 8 is removed. To secure a working space around. Next, the polishing device 38 is suspended from the upper part of the core, and the polishing device 38 is set on the header pipes 13 located on both sides of the T-tube 12 of the water supply sparger 9, and then the inspection range of the water supply nozzle 8 is polished. (S2). The water supply nozzle 8 is made of low-alloy steel, and its surface has adhered cladding and surface oxide film. Therefore, the surface of the inspection range is polished in advance to affect the flaw detection performance in the next step inspection. Then, the attached cladding and the surface oxide film are removed.

  After the polishing by the polishing device 38 is finished, the polishing device 38 is pulled up from the water supply nozzle 8. Subsequently, the double offset arm inspection device 24 is set in the water supply sparger 9 in the same procedure as the polishing device 38, and the corner portion 10 of the water supply nozzle 8 is inspected (flaw detection inspection) (S3).

  In the inspection (flaw detection inspection), the presence or absence of cracks on the surface of the corner portion 10 of the water supply nozzle 8 is confirmed using an eddy current flaw detection sensor (S4). If a crack is detected in the inspection (flaw detection inspection), a crack sizing including a crack depth measurement is performed as necessary (S5). Here, the crack sizing (S5) uses a device in which the flaw detection probe 17 of the double offset arm inspection device 24 is replaced with a UT sensor. Based on the result of the crack sizing (S5), the crack removal range is determined, the crack is removed by the polishing device 38 (S6), and then the presence of cracks is confirmed again by inspection (flaw detection inspection) ( S4) Repeat until there is no crack. When it is confirmed that there are no cracks in the presence or absence of cracks (S4), the maintenance work is completed, and the equipment in the furnace is restored (S7).

  By adopting such a method for maintaining the reactor pressure vessel nozzle of this embodiment, the water supply sparger 9 is avoided and the entire circumference of the corner portion 10 of the water supply nozzle 8 including the back surface of the water supply sparger 9 is inspected and polished. A series of operations such as polishing before inspection using the apparatus 38, inspection (inspection inspection), crack removal and the like can be performed, and the reactor pressure vessel nozzle can be maintained.

  According to the present invention, even in a corner portion of a water supply nozzle having poor accessibility, a water supply sparger composed of a T-shaped pipe and an annular header pipe arranged on the front surface is avoided, and the curvature shape is changed three-dimensionally. Since the corner of the feed water nozzle can be inspected and repaired, the surface of the reactor pressure vessel nozzle corner can be inspected and repaired during the operation period of the nuclear power plant.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel (RPV), 1A ... Bracket, 2 ... Shroud, 3 ... Upper lattice plate, 4 ... Core support plate, 5 ... Core sparger, 6 ... Core spray nozzle, 7 ... Core spray piping, 8 ... Water supply nozzle, 9 ... Water supply sparger, 10 ... Corner portion of water supply nozzle, 11 ... Thermal sleeve, 12 ... T-tube, 13 ... Header pipe, 14 ... Spray nozzle, 15 ... Taper pipe, 16 ... Single offset arm inspection device, 17, 28 ... flaw detection probe, 18 ... single offset arm, 18a ... first offset arm of single offset arm, 18b ... second offset arm of single offset arm, 19, 26, 42 ... drive unit, 20, 30, 43 ... Base, 21, 31, 44 ... Fixed part, 21a, 21b, 31a, 31b, 44 , 44b ... plate-like member, 21c, 31c, 44c ... mold taking part, 21d, 31d, 44d ... abutting part, 22, 27 ... turning direction, 23, 29 ... front-back direction, 24 ... double offset arm inspection device, 25, 41: Double offset arm, 25a, 41a ... First offset arm of double offset arm, 25b, 41b ... Second offset arm of double offset arm, 25c, 41c ... Third offset arm of double offset arm , 27, 45 ... turning direction, 29, 46 ... longitudinal direction, 32 ... flaw detection sensor, 33 ... shoe, 34 ... mechanical spring, 35 ... mounting seat, 36 ... tube, 37 ... elastic body, 38 ... polishing device, 39 ... Whetstone, 47 ... motor, 48 ... first gear, 49 ... second gear, 50 ... transmission mechanism.

Claims (20)

  A maintenance tool for inspecting and repairing the corner of the feed water nozzle where piping is present along the reactor wall of the reactor pressure vessel, and supporting the maintenance tool at the tip, and along the reactor wall of the reactor pressure vessel An offset arm that avoids existing piping and sets the maintenance tool at the corner of the water supply nozzle, and is arranged inside the piping of the piping existing along the reactor wall of the reactor pressure vessel to operate the offset arm A reactor pressure vessel nozzle maintenance device comprising: In the reactor pressure vessel nozzle maintenance apparatus according to claim 1,
The maintenance device for a reactor pressure vessel nozzle, wherein the maintenance tool is an inspection device for inspecting a corner portion of the water supply nozzle. In the reactor pressure vessel nozzle maintenance apparatus according to claim 2,
The inspection device includes a flaw detection probe that is set and inspected on a surface of a corner portion of the water supply nozzle, an offset arm that sets the flaw detection probe at an arbitrary position of the corner portion of the water supply nozzle, and the offset arm is the water supply A drive unit that swivels and / or moves back and forth according to the outer periphery of the corner portion of the nozzle, a base that supports the drive unit, and the base unit that is integrated with the base, and the inspection device is installed in the water supply sparger in the reactor pressure vessel A reactor pressure vessel nozzle maintenance device comprising: a fixing portion for fixing the reactor. In the reactor pressure vessel nozzle maintenance apparatus according to claim 3,
The drive unit includes a pivot shaft that pivots the offset arm along a corner portion of the water supply nozzle, and a front and rear shaft that drives the offset arm in the front-rear direction to press the flaw detection probe against the corner portion of the water supply nozzle. With
The swivel shaft is driven by a motor and a speed reducer built in the drive unit, and the front and rear shafts are driven by a slide mechanism that operates the drive unit along the base. Reactor pressure vessel nozzle maintenance device. In the reactor pressure vessel nozzle maintenance apparatus according to claim 3 or 4,
The fixing portion is composed of two plate-like members so as to sandwich the base from both sides, and the upper portion of each plate-like member extends in the extending direction of the flaw detection probe, and the tip thereof is the shape of the water supply sparger. And a lower part of each plate-like member extends in the extending direction of the flaw detection probe, and a tip part of the tip part forcing the inclination of the fixing part is formed. A reactor pressure vessel nozzle maintenance device characterized in that: In the reactor pressure vessel nozzle maintenance apparatus according to any one of claims 1 to 5,
The flaw detection probe includes a flaw detection sensor that is set and inspected on the surface of the corner portion of the water supply nozzle, a shoe that fixes the flaw detection sensor, and a mounting seat that attaches the flaw detection sensor fixed to the shoe to the offset arm. A reactor pressure vessel nozzle maintenance device comprising: a spring supported by the mounting seat and pressing the flaw detection sensor against a corner portion of the water supply nozzle. In the reactor pressure vessel nozzle maintenance apparatus according to any one of claims 1 to 5,
The flaw detection probe includes a flaw detection sensor that is set and inspected on the surface of the corner portion of the water supply nozzle, a shoe that fixes the flaw detection sensor, and a mounting seat that attaches the flaw detection sensor fixed to the shoe to the offset arm. A reactor pressure vessel nozzle maintenance device comprising: a tube supported by the mounting seat and pressing the flaw detection sensor against a corner portion of the water supply nozzle with fluid pressure. In the reactor pressure vessel nozzle maintenance apparatus according to any one of claims 1 to 5,
The flaw detection probe includes a flaw detection sensor that is set and inspected on the surface of the corner portion of the water supply nozzle, a shoe that fixes the flaw detection sensor, and a mounting seat that attaches the flaw detection sensor fixed to the shoe to the offset arm. A reactor pressure vessel nozzle maintenance device comprising: an elastic body supported by the mounting seat and pressing the flaw detection sensor against a corner portion of the water supply nozzle. In the reactor pressure vessel nozzle maintenance device according to any one of claims 6 to 8,
The apparatus for maintaining a reactor pressure vessel nozzle, wherein the flaw detection sensor is a film-like eddy current flaw detection sensor. In the reactor pressure vessel nozzle maintenance apparatus according to claim 1,
The maintenance device for a reactor pressure vessel nozzle, wherein the maintenance tool is a polishing device for polishing a corner portion of the water supply nozzle. In the reactor pressure vessel nozzle maintenance apparatus according to claim 10,
The polishing apparatus includes a grindstone that is set and polished on a surface of a corner portion of the water supply nozzle, an offset arm that sets the grindstone at an arbitrary position of the corner portion of the water supply nozzle, and the offset arm is disposed on the water supply nozzle. A drive unit that swivels and / or moves back and forth according to the outer periphery of the corner part, a base that supports the drive part, and the base are configured integrally, and the polishing apparatus is fixed to a water supply sparger in the reactor pressure vessel. A reactor pressure vessel nozzle maintenance device comprising: In the reactor pressure vessel nozzle maintenance apparatus according to claim 11,
The drive unit includes a pivot shaft that pivots the offset arm along a corner portion of the water supply nozzle, and a front and rear shaft that drives the offset arm in the front-rear direction to press the grindstone against the corner portion of the water nozzle. Prepared,
The swivel shaft is driven by a motor and a speed reducer built in the drive unit, and the front and rear shafts are driven by a slide mechanism that operates the drive unit along the base. Reactor pressure vessel nozzle maintenance device. The maintenance device for a reactor pressure vessel nozzle according to claim 11 or 12,
The fixed part is composed of two plate-like members so as to sandwich the base from both sides, and the upper part of each plate-like member extends in the extending direction of the grindstone, and the tip part thereof has the shape of the water supply sparger. And a lower portion of each plate-like member extends in the extending direction of the grindstone, and a tip portion is formed to force the inclination of the fixed portion. A reactor pressure vessel nozzle maintenance device characterized by comprising: In the reactor pressure vessel nozzle maintenance apparatus according to claim 1,
The maintenance device for a reactor pressure vessel nozzle, wherein the maintenance tool is an ultrasonic flaw detection sensor that performs crack sizing of a corner portion of the water supply nozzle. The reactor pressure vessel nozzle maintenance apparatus according to any one of claims 1 to 14,
The offset arm is a single offset arm that is offset in one direction with respect to the axis center of the drive unit, or an arm that is offset in one direction with respect to the axis center of the drive unit is a circumference of the water supply nozzle corner. A maintenance device for a reactor pressure vessel nozzle, wherein the maintenance device is a double offset arm further offset in a direction. When inspecting and repairing the corner of the water supply nozzle where piping exists along the reactor wall of the reactor pressure vessel,
A maintenance tool fixed to the tip of the offset arm is set at the corner of the water supply nozzle avoiding the piping existing along the reactor wall of the reactor pressure vessel, and the reactor wall of the reactor pressure vessel A maintenance method for a reactor pressure vessel nozzle, characterized in that the offset arm is operated by a drive unit disposed inside a furnace of a pipe existing along the pipe to inspect and repair the corner portion of the water supply nozzle. In the maintenance method of the reactor pressure vessel nozzle according to claim 16,
A maintenance method for a reactor pressure vessel nozzle, wherein the maintenance tool is a flaw detection probe, and the flaw detection probe is set on a surface of a corner portion of the water supply nozzle for inspection. The method for maintaining a reactor pressure vessel nozzle according to claim 17,
Before the inspection of the corner portion of the water supply nozzle by the flaw detection probe, there is a procedure for polishing and removing the deposited clad and surface oxide film on the surface of the corner portion of the water supply nozzle by a polishing apparatus. Conservation method. In the maintenance method of the reactor pressure vessel nozzle according to claim 17,
When it is determined that there is a crack in the procedure for determining the presence or absence of a crack in the corner of the water supply nozzle and the procedure for determining the presence or absence of the crack based on the inspection result by the flaw detection probe, an ultrasonic flaw detection sensor is used. A method for maintaining a reactor pressure vessel nozzle, comprising: a step of performing crack sizing and determining a crack removal range of a corner portion of the water supply nozzle; and a step of polishing and removing a crack using a polishing apparatus. In the maintenance method of the reactor pressure vessel nozzle according to claim 19,
A method for maintaining a reactor pressure vessel nozzle, wherein the procedure returns to the procedure of performing crack sizing again after the procedure of removing and polishing cracks using the polishing apparatus, and the procedure is repeated until the removal of cracks is completed.

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