JP2000304887A - Internal pump casing welded part inspection device for nuclear reactor pressure vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a use amount of water and to stably move an inspection head. SOLUTION: A turn ring 24 having a circumferential direction split structure is provided in the periphery of an upper end part of an internal pump casing 7 such that the turn ring 24 is liquid-tightly disposed in a gap G of a pump nozzle 6 part. A base ring 23 is fixed to the periphery of the upper end part of the internal pump casing 7 such that the base ring 23 holds the turn ring 24. A turn drive device 25 for turning the turn ring 24 is attached to the base ring 23. An inspection head 27 vertically movable by an elevation drive device 26 is installed to the turn ring 24. A welded part 8 is inspected with water filled above the liquid-tight part of the turn ring 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for an internal pump casing weld of a reactor pressure vessel, in which an internal pump is installed by penetrating a lower head portion of the reactor pressure vessel.

[0002]

2. Description of the Related Art As one type of nuclear reactor, an improved boiling water reactor (ABWR) is known, which is a conventional reactor for a boiling water reactor (BWR). ) Is a so-called wet motor type internal pump, which is installed inside the container by penetrating the lower head plate, so that the thick external piping can be eliminated. It is possible to improve reliability, improve economic efficiency, and reduce exposure.

In the above-mentioned improved boiling water reactor, the structure of the part where the internal pump is installed in the reactor pressure vessel is, as shown in FIG. Forming an opening 3 penetrating in the vertical direction,
A pump nozzle stub 4 as a safe end having an outer tube 4a having the same inner diameter as the opening 3 and an inner tube 4b having an outer diameter smaller than the opening 3 is provided at the upper end edge of the opening 3. A skirt 5 is provided at the lower end edge of the opening 3 so that the outer tube portion 4a of the pump nozzle stub 4 extends upward outside the container to form a pump nozzle 6 having a double tube structure. The upper end of an internal pump casing (motor casing) 7 is integrally joined to the lower end of the inner pipe portion 4b of the pump nozzle 6 by welding (welded portion 8),
The drive motor unit 9 side of the internal pump 12 having the drive motor unit 9, the shaft unit 10, and the fan unit 11 is housed in the internal pump casing 7 so that the shaft unit 10 passes through the pump nozzle 6. , The fan section 11
Is supported on the shroud 13 side in the reactor pressure vessel 1.

[0004] In the structure of the part where the internal pump 12 is installed, the inner pipe portion 4 b of the pump nozzle stub 4 is provided.
The inspection of the welded portion 8 between the lower end of the inner pump casing 7 and the upper end of the internal pump casing 7 is an indispensable item, and therefore, ultrasonic inspection is performed.

Conventionally, when performing the ultrasonic inspection for the welded portion 8, as shown in FIG.
Utilizing the notch 5a (see also FIG. 5) provided in the skirt portion 5, a turning rail 15 and a turning rail support 16 of a circumferentially divided structure having an inspection head (UT head) 14 are provided.
Is mounted on the outer periphery of the upper end portion of the internal pump casing 7, and the gap G of the double nozzle structure of the pump nozzle 6 portion, that is, the outer peripheral surface from the inner pipe portion 4b to the upper end portion of the internal pump casing 7 A gap G between the opening 3 and the inner peripheral surface is interposed in a watertight state, and a drive mechanism 17 for turning the turning rail 15 and an elevating base 18 for raising and lowering the turning rail support 16 are sealed with water. The inspection device main body drive unit 20 covered by the cover 19 is attached to the notch 5 a of the skirt portion 5, and water is sealed in the gap G from inside the main body drive unit 20. The flaw detection inspection of the welded portion 8 is performed by moving the welded portion 8 in the vertical direction and the vertical direction. Reference numeral 21 denotes an ultrasonic flaw detector, and reference numeral 22 denotes a control device for operating the ultrasonic flaw detector 21 and the main body driving unit 20.

[0006]

However, in the case of the ultrasonic flaw detection inspection by the above-mentioned conventional inspection apparatus, the pump nozzle 6
Not only the gap G of the section but also the entire body drive section 20, the water must be sealed entirely, so that a large capacity (about 20
(Liter) of water is required, so that there are many places to be sealed, and the whole apparatus becomes complicated and large, and it takes time to mount and remove the apparatus.
Is attached to the skirt 5 on the side of the reactor pressure vessel 1.
, The center misalignment occurs between the inspection head 14 and the internal pump casing 7, and as a result, the probe of the inspection head 14 may be tilted during the elevating operation or the turning operation, and the Scanning was sometimes hindered.

Therefore, the present invention enables the amount of water to be used to be reduced, and suppresses misalignment between an inspection head and an internal pump casing.
An object of the present invention is to provide an inspection apparatus for an internal pump casing weld of a reactor pressure vessel capable of stably scanning a probe.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a lower end plate of a pump nozzle provided as a double tube structure on a lower head plate of a reactor pressure vessel and an upper end of an internal pump casing. In an internal pump casing weld inspection system for a reactor pressure vessel for ultrasonic inspection of welds with a base ring having a circumferentially divided structure capable of being fixed to an outer peripheral position of an upper end portion of the internal pump casing A swivel ring having a circumferentially divided structure in which the pump nozzle is arranged in a watertight manner in a gap formed by a double pipe structure, and a lower end of the swivel ring is rotatably held by the base ring; A turning drive device attached to an outer portion of the base ring to turn the turning ring, and a lifting / lowering drive assembled to the turning ring And a test head to be able to lift at a position above the pivot ring by the device, a configuration in which to be able to feed water to the revolving ring upward in the gap through the revolving ring.

[0009] Since the area for filling with water is only the upper part of the swirl ring, the filling capacity of water can be reduced. In addition, since the entire apparatus is installed with reference to the internal pump casing, misalignment with respect to the internal pump casing hardly occurs when the inspection head moves, and the movement is stabilized.

Further, as a means for arranging the swirl ring in the gap in a watertight manner, an O-ring is attached to the upper end of the inner and outer peripheral surfaces of the swirl ring, so that the water filling capacity can be further reduced. Become like

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show an embodiment of the present invention, in which a lower end of an inner pipe portion 4b of a pump nozzle 6 provided as a double pipe structure on a lower head plate 2 of a reactor pressure vessel 1 is connected to an internal part. In an internal pump casing weld inspection system for a reactor pressure vessel for ultrasonic inspection of a weld 8 with the upper end of the pump casing 7, the upper end of the internal pump casing 7 can be fixed at an outer peripheral position. A gap G formed by a double tube structure of the base ring 23 having a circumferentially divided structure and the pump nozzle 6 part.
To be placed watertight within the base ring 2
3, a turning ring 24 having a circumferentially divided structure in which a lower end portion is rotatably held, a turning driving device 25 attached to an outer portion of the base ring 23 to turn the turning ring 24, An inspection head 27 which can be moved up and down at a position above the swivel ring 24 by an elevating drive device 26 assembled to the swivel ring 24;
It is configured so that water can be injected into the inside and filled.

More specifically, as shown in FIGS. 2 and 3, the base ring 23 is, for example, a circumferentially divided structure including four divided segments 23a, and is provided with a connecting tool such as a snap lock provided at the divided portion. A rubber 30 is attached to the inner peripheral surface of the base 29 so as to make close contact with the outer peripheral surface of the upper end portion of the internal pump casing 7.
Has a ring-shaped guide groove 32 for fitting the ring-shaped protrusion 31 on the lower end surface thereof to guide the turning of the turning ring 24, and has an inverted L-shape on the outer peripheral portion of the base portion 29. The raised holding frame 33 is integrally raised inward so that a rack gear 34 provided on the outer periphery of the lower end of the revolving ring 24 can be stored and held inside the holding frame 33. Further, the rack gear 3 is attached to the holding frame portion 33 of one divided segment 23a.
The window 35 for exposing the portion 4 is partially opened.

As shown in FIGS. 2 and 3, the turning drive device 25 has a gear casing 36 which is attached to the window 35 of the holding frame 33 of the base ring 23. A drive gear 38 driven by a motor 37 attached to the outside of the lower part and a reduction gear 39 meshing with the drive gear 38 are housed therein. Of the rack gear 34.

As shown in FIGS. 2 and 3, the revolving ring 24 has, for example, a circumferentially divided structure composed of four divided segments 24a in the same manner as the base ring 23, as described above. Guide groove 3
2 and a rack gear 34 for receiving a turning force from a reduction gear 39 of the turning drive device 25 is provided on the outer periphery of the lower end. Is provided with a tap hole 40 in the tangential direction in the division surface portion of one adjacent divided segment 24a, and
a number wall portion 41 is formed by digging an inner thickness portion from the outside in a tangential direction at an end position of a, and a through hole 42 provided in the number wall portion 41.
Each of the divided segments 23a can be connected and separated by a loosening operation of the bot 43 screwed into the tap hole 40 through a through hole. Further, a divided structure is formed at the upper end of each of the inner peripheral surface and the outer peripheral surface. The rings 44 and 45 are attached by bonding so that the O-rings 44 and 45 are brought into close contact with the inner and outer peripheral surfaces of the gap G.

As shown in detail in FIGS. 3 and 4, the inspection head 27 is provided with openings 47a and 47b at left and right positions on an inner peripheral surface of a casing 46 having a hollow segment shape. A plurality (two in the present embodiment) of probes 49a and 49b are assembled so as to be urged inward by springs 48 from the respective members 47b.

The lifting drive 2 for the inspection head 27
6 is one of the turning units 24 as shown in FIGS.
A ball screw 50 whose lower end is rotatably penetrated from above into the two divided segments 24a so as to be screwed into the inspection head 27, and a ball screw 50 of the divided segment 24a which stands at a position sandwiching the ball screw 50 in the circumferential direction. The support rod 51 provided, a stopper frame 52 rotatably supporting the upper end of the ball screw 50 and fixedly supporting the upper end of the support rod 51, and the stopper frame 52 installed in the divided segment 24a via the coupling 53. A motor 54 connected to the lower end of the ball screw 50, an O-ring 55 attached to a portion where the lower end of the ball screw 50 passes through the divided segment 24a, an O-ring presser 56 attached to these penetrating portions, a bearing 57, bearing presser 5
8 and the like.

Further, as shown in FIGS. 2 and 4, a water supply hose 59 for filling the gap G above the swirl ring 24 sealed by the O-rings 44 and 45 with water is provided on the outer peripheral surface of the swirl ring 24. After being guided through the upper end face portion into the casing 46 of the inspection head 27, it is provided so as to be opened at the inner peripheral surface portion of the casing 46.

In FIG. 1, the same parts as those in FIG. 6 are denoted by the same reference numerals. Although not shown, the present invention also includes an ultrasonic flaw detector 21 and a controller 22 as shown in FIG.

When ultrasonic inspection is to be performed on the welded portion 8 between the lower end of the inner pipe portion 4b of the pump nozzle 6 and the upper end of the internal pump casing 7, the skirt portion 5 of the pump nozzle 6 is required.
First, the split segments 24a of the swivel ring 24 in the split state are arranged at the outer peripheral position of the upper end portion of the internal pump casing 7 by utilizing the notch 5a, and the swivel ring 24 is sequentially connected. Attach 24. In this case, as shown in FIG. 2, the connection between the divided segments 24a
This is performed by screwing a bolt 43 into a tap hole 40 provided on the end face of the other divided segment 24a through a through hole 42 provided in the number wall portion 41 of a. For the segment 24a to which the inspection head 27 is attached, the inspection head 2
7 is inserted into an upper position in the gap G of the pump nozzle 6 and the divided segments 24a
As shown in FIG. 3, the arrangement is such that the O-ring 45 at the upper end of the outer peripheral surface is located above the upper edge level of the notch 5a.

Next, the divided segments 23a of the base ring 23 in the divided state are arranged so as to surround the position of the rack gear 34 at the lower end of the revolving ring 24.
The base ring 23 is mounted by sequentially connecting. In this case, the connection of the divided segments 23a is performed by the connecting member 28 of the divided portion, but the connection of the divided segment 23a to which the turning drive device 25 is assembled is finally performed at the cutout 5a. When the base ring 23 is mounted in this manner, the rubber 30 on the inner peripheral surface of the base portion 29 is pressed against the outer peripheral surface of the upper end portion of the internal pump casing 7 so that the base ring 23
Can be fixed, and at the same time, the reduction gear 39 of the turning drive device 25 can be meshed with the rack gear 34.

Thereafter, when water is supplied through the water supply hose 59, the O-rings 44 and 45 at the upper end portions of the inner and outer peripheral surfaces of the swirl ring 24 are in close contact with the inner and outer peripheral surfaces forming the gap G. Only the upper region sealed by 44 and 45 will be filled with water.

In the above state, the height of the inspection head 27 is adjusted to align the probes 49a and 49b with the welding portion 8, and then the inspection head 27 is swiveled together with the swivel ring 24 to perform ultrasonic inspection. To do.

The height of the inspection head 27 is adjusted by driving the motor 54 of the elevation drive unit 26 to rotate the ball screw 50. However, since the support rod 51 is set up in parallel with the ball screw 50. , Inspection head 27
Can be raised and lowered stably.

On the other hand, the turning of the inspection head 27 is performed by transmitting the driving force of the motor 37 of the turning drive unit 25 from the driving gear 38 to the rack gear 34 via the reduction gear 39 to turn the turning ring 24. The rotation of the ring 24 is given as a movement of the guide groove 32 of the base ring 23 fixed to the outer periphery of the upper end portion of the internal pump casing 7 by the movement of the projection 31 on the lower end face, so that the inspection head 27 and the internal pump casing 7 Therefore, it is possible to stably scan the probes 49a and 49b.

In the above, only the region above the position sealed by the O-rings 44 and 45 at the upper and lower ends of the inner and outer circumferences of the swirl ring 24 needs to be filled with water. And can be greatly reduced. For example, instead of the O-ring 44 on the inner peripheral surface of the swirl ring 24, for example, a seal ring is interposed between the lower end surface of the swivel ring 24 and the upper surface of the base 29 of the base ring 23, The inner circumference of the gap G can be sealed with the rubber 30 of the ring 23, but as described above,
It is more advantageous to attach the O-ring 44 to the upper end of the inner peripheral surface of the swirl ring 24 because the amount of water filling is smaller.

In the present invention, as described above,
Since the filling capacity of water can be greatly reduced,
Since the entire device can be significantly reduced in size and weight and the structure itself can be simplified, installation and removal operations are also facilitated.

In the above embodiment, the water supply hose 5
9 is guided to the position of the inspection head 27, but any position may be used as long as it is above the O-rings 44 and 45. The number of divisions of the base ring 23 and the swivel ring 24 is arbitrary. It goes without saying that various changes can be made without departing from the scope of the present invention.

[0029]

As described above, according to the present invention, the welded portion between the lower end of the inner pipe portion of the pump nozzle and the upper end of the internal pump casing provided as a double pipe structure on the lower head plate of the reactor pressure vessel is provided. In an internal pump casing weld inspection device for a reactor pressure vessel for ultrasonic flaw detection, a base ring having a circumferentially divided structure capable of being fixed to an outer peripheral position of an upper end portion of the internal pump casing, and the pump nozzle A swivel ring having a circumferentially divided structure, which is arranged in a watertight manner in a gap formed by the double pipe structure, and a lower end of which is rotatably held by the base ring; A swing drive device attached to the section to swing the swivel ring, and a swivel drive device mounted on the swivel ring. Inspection head that can move up and down at the position above the swing ring, and water is supplied to the gap above the swivel ring through the swivel ring. In comparison, the filling capacity of water can be significantly reduced, thereby reducing the size and weight of the entire device, and having a structure in which the entire device can be installed with reference to the internal pump casing. Therefore, even when the inspection head is moved, misalignment with respect to the internal pump casing is unlikely to occur, so that the probe can be scanned stably, and further, as means for arranging the swirl ring in the gap in a watertight manner, By using an O-ring attached to the upper end of the inner and outer peripheral surfaces of the revolving ring, the water filling capacity can be further reduced. Can be, there is exhibited an excellent effect that.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an internal pump casing weld inspection system for a reactor pressure vessel of the present invention.

FIG. 2 is an exploded perspective view showing a part of FIG. 1 in an enlarged manner.

FIG. 3 is a longitudinal sectional view of a main part.

FIG. 4 is a front view of the inspection head.

FIG. 5 is a schematic diagram showing a structure of a part of an improved boiling water reactor in which an internal pump casing is installed in a reactor pressure vessel.

FIG. 6 is a schematic diagram of a conventional inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 2 Lower end plate 4b Inner tube part 6 Pump nozzle 7 Internal pump casing 8 Welding part 23 Base ring 24 Swirl ring 25 Swirl drive device 26 Elevation drive device 27 Inspection head 44, 45 O-ring G gap

Claims (2)

[Claims] A reactor pressure vessel for ultrasonically inspecting a weld between a lower end of an inner pipe portion of a pump nozzle and an upper end of an internal pump casing provided on a lower end plate of a reactor pressure vessel as a double pipe structure. In the internal pump casing weld inspection device, a base ring having a circumferential division structure that can be fixed to an outer peripheral position of an upper end portion of the internal pump casing, and a gap formed by a double pipe structure of the pump nozzle are provided. A pivot ring having a circumferential division structure in which the lower end portion is pivotally held by the base ring, and the pivot ring is attached to an outer portion of the base ring to pivot the pivot ring. And a lifting drive unit attached to the above-mentioned swivel ring so that it can be raised and lowered at a position above the swivel ring. And an inspection head for the internal pump casing of the reactor pressure vessel, characterized in that water can be supplied into the gap above the swirl ring through the swivel ring. 2. The inspection of the internal pump casing weld of the reactor pressure vessel according to claim 1, wherein an O-ring is attached to an upper end portion of an inner and outer peripheral surface of the swirl ring as means for water-tightly disposing the swirl ring in the gap. apparatus.