JP3288924B2 - In-core inspection equipment for nuclear reactors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an in-reactor inspection apparatus used in a reactor pressure vessel.
The present invention is suitable for an apparatus for inspecting a weld line related to a shroud, which is one of the reactor internals in a reactor pressure vessel, from an outer surface side of the shroud.

[0002]

2. Description of the Related Art A conventional in-core inspection apparatus for inspecting a welding line of a shroud from the outer surface of the shroud in a reactor pressure vessel has been filed in Japanese Patent Application No. Hei 6-252221.

[0003] There, a circumferential moving mechanism is provided on a flange portion of the shroud, and a mast which is movable in the axial direction and has a plurality of bending mechanisms is attached to the moving mechanism. With an ultrasonic probe, the ultrasonic probe is scanned along the outer surface of the shroud,
The content of confirming the soundness of the welding line of the shroud is disclosed.

[0004]

The inspection apparatus is placed between the inner wall surface of the reactor pressure vessel and the outer wall surface of the shroud for inspection work. On the other hand, there are many jet pump equipment between the inner wall surface of the reactor pressure vessel and the outer wall surface of the shroud, so that the space between the equipment and the outer wall surface of the shroud is narrower.

In the above prior art, since the mast is bent by a power source such as a motor, it is necessary to incorporate a bending mechanism inside the mast, and since the mast needs a margin for incorporating the mechanism, the thickness of the mast increases. And increase the weight.
If the weight increases, the mast must be naturally thickened to increase the strength.

In addition, since a space for bending is required inside the pressure vessel, it may be difficult to apply the method to a plant in which the space between the shroud and the jet pump is narrow.

Further, in the prior art, the mast length after bending is shorter than that at the time of installation because the mast is bent after the device is installed in the state of a straight rod and installed.

Therefore, it is difficult to reach the inspection means to the upper surface of the baffle plate. An object of the present invention is to provide an in-furnace inspection apparatus that enables an in-furnace inspection in a narrow place.

[0009]

A first means for achieving the above object is to insert an inspection means supported by a support means into a reactor pressure vessel and press the inspection means against an object to be inspected by a pressing means. In the in-core inspection device for a nuclear reactor, the support means has a flexible structure that can be bent over substantially the entire length, and includes a holding frame in which the inspection means is attached to the flexible structure. As a pressing means, a supporting means is supported at a lower end portion of the supporting means, and a jetting means of the fluid is used as a pressing force of the testing means with a jetting reaction force of the fluid. A bending mechanism for bending a part of the means toward the object to be inspected , and further ejecting a fluid to the flexible structure.
Means by means of the flexible structure by means of the fluid ejection
Equip it with the direction of approaching the inspection object by the ejection reaction force
In some it is furnace inspection system of a nuclear reactor which was characterized by the testing means is lowered hanging said support means to said reactor pressure vessel, appended supported by said support means, bending mechanism in the middle of the support means Bending toward the inspection object, and further ejecting the fluid from the ejection means of the fluid, the holding frame is moved toward the inspection object together with the inspection means by the ejection reaction force, and the inspection means is moved toward the inspection object. Pressing the inspection object to inspect the inspection object by the inspection means, and further,
The support means comprising the flexible structure is provided with a hand for ejecting the fluid.
Adhering to the inspection object by the reaction force of the fluid jet by the step
Make sure that the support means is not in the
The step is separated from the inspection object by the horizontal component force due to the weight of the support means.
The effect of preventing the occurrence is obtained.

[0010]

[0011] The second means is also the first means , wherein the flexible structure comprises a chain in which the axis of the chain element is oriented in the circumferential direction of the reactor pressure vessel in parallel at intervals in the circumferential direction. An in-reactor inspection device for a nuclear reactor characterized by having a deployed configuration, in which the axis of the chain element of the chain is oriented in the circumferential direction of the reactor pressure vessel, so the rigidity increases in the circumferential direction. In addition, when scanning the inspection means in the circumferential direction, an effect is obtained that the scanning in the circumferential direction can be accurately performed irrespective of the flexible structure of the supporting means.

[0012] Similarly, the third means is the reactor inspection apparatus according to the second means , wherein the parallel chains are connected by a holding plate to maintain a constant parallel interval. Each of the parallel chains is connected by a holding plate to reduce the degree of freedom of relative movement, so that the rigidity of the support means in the circumferential direction is higher, and the support means is used when scanning the inspection means in the circumferential direction. However, there is an effect that the scanning in the circumferential direction can be performed more accurately irrespective of the flexible structure.

A fourth means is the reactor according to the third means , wherein a cable to the inspection means and a hose to the fluid ejection means are provided along the chain, surrounded by the holding plate. In addition to the action of the fourth means, the cable and the hose are surrounded by the holding plate and can move integrally with the chain, and do not vary. The effect of easy handling is obtained.

A fifth means is the inspection apparatus main body detachably mounted on the upper part of the shroud in the reactor pressure vessel in any one of the first means to the fourth means. A reactor for moving the inspection device body in the circumferential direction along the shroud; and an elevating device for moving the support device up and down from the inspection device body. The inspection device main body is attached to the upper part of the shroud, and the inspection device main body is moved along the shroud by the circumferential direction moving means, so that the support means is moved in the circumferential direction. Is moved up and down, and the scanning and positioning of the inspection means can be easily performed.

The sixth means is the same as the fifth means , except that the supporting means is provided with a tension applying means for applying tension via a movable chain sprocket, and the movement stroke of the chain sprocket is determined by the scanning stroke of the inspection means. An in-reactor inspection device for a nuclear reactor, characterized in that the chain has been reduced by a factor of two or more. Can be moved by the lifting / lowering means to scan the inspection means while making a stroke, so that there is obtained an effect that the scanning amount is hardly disturbed.

Similarly, the seventh means is any one of the first means to the sixth means, and further comprises means for changing the ejection energy of the fluid from the ejection means in at least two levels. An in-core inspection apparatus for a nuclear reactor, characterized in that, in addition to the operation of any one of the first means to the seventh means, the injection means is pressed against the inspection object by increasing the ejection energy. Get enough power,
By reducing the ejection energy, an effect is obtained in that the pressing force of the inspection means against the inspection object is reduced, and the inspection means easily moves along the inspection object together with the support means.

Eighth means is the same as any one of the first means to the seventh means, wherein the holding frame is provided with a link which is rotatable in the direction of the object to be inspected and which can be moved back and forth. An in-reactor inspection apparatus for a nuclear reactor characterized by being equipped with a fluid jetting means and an inspection means, in addition to the operation of any one of the first means to the eighth means, Due to the reaction force of the ejection of the fluid from the ejection means, the link rotates and comes and goes in the direction of the object to be inspected, so that the inspection means is pressed against the object to be inspected and is subjected to the inspection.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

A shroud 1 also having a ring-shaped flat cross section is provided in a reactor pressure vessel having a ring-shaped flat section by being submerged in cooling water (reactor water) in the reactor pressure vessel.

FIG. 1 shows a state in which the furnace inspection apparatus of the present invention is installed on the upper flange 9 of the shroud and the lower body 4 is inspected.

The shroud 1 having a ring-shaped flat cross section has a cylindrical shape as a whole.
The lower trunk 4 is divided into three parts.

The diameters of the upper cylinder 2, the intermediate cylinder 3,
It becomes smaller in the order of the lower torso 4. FIG. 1 shows a state in which some of them have been cut out.

A flange 5 is provided at each boundary, and a circumferential welding line 6 exists above and below it.

Further, a circumferential welding line 6 is provided substantially at the center of the intermediate body 3.
And a circumferential weld 6 with the shroud support 7 also exists below the lower body 4.

The present invention is directed to inspection of these girth weld lines.

The in-furnace inspection apparatus according to the present invention comprises an inspection apparatus main body 8 mounted on a shroud upper flange 9 so as to be freely and detachably mounted thereon, and a support means which is vertically extended from the inspection apparatus main body 8 and is removably supported. 14, a holding frame 18 attached to and supported by the lower end of the supporting means 14, an inspection means 17 attached to the holding frame 18, and the like.

The inspection apparatus main body 8 includes a drive motor 33 for driving on the upper shroud flange 9 and a drive wheel 10.
Are provided, and at least one or more guide wheels 11 are provided on the outer surface side and the inner surface side of the shroud 1 in order to prevent the drive wheels 10 from falling off.

At least one of the guide wheels 11 is provided with an encoder 12 for measuring the amount of movement in the circumferential direction.

The drive wheels are provided on the upper shroud flange 9.
It is desirable to provide a taper according to the diameter.

The support means 14 is mounted so as to be able to move up and down by using the inspection apparatus main body 8 as a guide.

As the supporting means 14, two chains 16 are arranged in parallel at an interval and connected to each other so as to prevent misalignment.

Since the support means 14 is constituted by the chain 16, the support means 14 accesses a narrow portion such as a gap between a shroud 1 and a jet pump riser brace (not shown) for supporting a jet pump installed in the reactor. It can be made thin enough to do so.

A bending mechanism 13 is provided below the inspection apparatus main body 8.
Is provided, and the support means 14 can be made to follow the wall surface of the intermediate cylinder 3 of the shroud.

Further, since the supporting means 14 is constituted by the chain 16, it can be bent at an arbitrary position.
The lowering portion of the inspection apparatus main body 8 is supported by the supporting means 14 by the lifting drive gear 21 inside the inspection apparatus main body 8 while the lower portion is bent.
Can be moved up and down.

With such a structure, the inspection means 17 can be easily approached to the upper surface of the baffle plate 34.

At the lower end of the support means 14, an inspection means 17 and a holding frame 18 for holding the inspection means 17 are provided.

In this embodiment, an ultrasonic probe 19 and a television camera 20 are mounted as the inspection means 17.

FIG. 3 is a side view of the basic structure inside the inspection apparatus main body 8.

The elevation drive gear 21 is positioned as low as possible in order to secure the positioning accuracy of the inspection means 17.

The chain 1 inside the inspection apparatus main body 8
In order to prevent misalignment due to the loosening of 6, the drive gear 22 is also arranged near the upper outlet.

Further, an air cylinder 2 is provided between the gears.
3 is provided as a tension applying means, and a constant tension is always applied to the chain 16 between the drive gears, thereby preventing the chain 16 from loosening and coming off.

The chain sprocket 40 on which the chain 16 is hung is rotatably mounted on an air cylinder 23 acting to push up the chain sprocket 40. The movement stroke of the chain sprocket 40 by the air cylinder 23 is one of the scanning stroke of the inspection means. / 2 or more, and the chain sprocket 40 can stroke up to the position indicated by the dotted line in FIG. 3, and even if the upper drive gear is fixed, the chain sprocket 4
The amount twice as large as 0 can be fed downward without slack by the drive gear.

FIG. 4 shows a cross section of the support means 14.

The two chains 16 are a continuation of the chain elements shown in FIG. 4, and the connecting points are freely bendable, so that they have the flexibility of being able to bend anywhere in the entire length of the chain 16, The bending direction is a rotation direction about the center line A in FIG. 4 and does not bend in the longitudinal direction of the center line A (the direction of the axis of the chain element).

The two chains 16 are connected to each other by a holding plate 35 at regular intervals in the length direction.

The holding plate 35 is a set of two front and back plates.

There is a gap 24 between the holding plates 35, and an ultrasonic signal cable 25, a video signal cable 26 from a camera, a water hose 27, and the like are incorporated in the gap 24.

FIG. 5 shows the supporting means 14 and the holding frame 1.
8 illustrates the structure of FIG.

The supporting means 14 and the holding frame 18 include
At least one or more pressing means 28 is provided;
By jetting the water stream 29 from here, a pressing force against the wall of the lower trunk 4 of the shroud is obtained.

The pressing means 28 comprises a nozzle for ejecting a fluid, a hose connected to the nozzle, and a high-pressure fluid supply means for supplying high-pressure fluid pressurized by a pump through the hose to the nozzle. When it is desired to change the ejection energy, the degree of pressure increase by the pump is changed, or the amount of fluid supplied to the nozzle is changed by restricting the amount of fluid supplied to the nozzle by a regulating valve provided in a fluid flow path near the pump outlet.

The shape of the lower trunk 4 of the shroud differs depending on the plant.

These are generally classified into a cylindrical shape having a flange as shown in FIG. 6A and an inverted conical shape as shown in FIG. 6B.

Since the support means in the present invention can be bent at any position, it can be applied to any shroud lower body.

Next, a series of operations of the present apparatus will be described.

First, the apparatus is suspended in the furnace by a hoist (not shown) of the refueling cart. At this time, the shape of the apparatus is set to the shortest state as shown in FIG. 2 for easy handling.

Next, the device is placed on the upper shroud flange 9 at a position where the lower part of the support means 14 does not hit a jet pump (not shown).

At this time, the guide wheel (not shown) on the inner surface of the shroud of the guide wheels 11 is largely separated from the inner surface of the upper flange 9 of the shroud in order to facilitate installation of the apparatus.

Monitoring when the apparatus is placed on the upper flange 9 of the shroud is performed by an underwater TV camera (not shown) prepared separately from the apparatus.

When the apparatus rides on the shroud 1, an inner guide wheel (not shown) provided on the inspection apparatus main body 8 at a position facing the guide wheel 11 with the shroud 1 interposed therebetween.
Is brought into close contact with the inner surface of the upper shroud flange 9 by an air cylinder (not shown). As a result, the device is pressed from the outer surface and the inner surface of the upper shroud flange, and the device does not fall out of the shroud 1.

Next, as shown in FIG.
As a result, the bending mechanism 13 is bent from a straight state, and the inspection means 17 is made to follow the intermediate cylinder 3 of the shroud.

Further, the driving wheel 10 and the driving gear 2
In step 1, the inspection unit 17 is moved to a target inspection start position.

The position detection in the circumferential direction is performed based on a signal from an encoder 12 connected to a guide wheel 11 provided separately from the drive system in consideration of the slip of the drive wheel 10.

The vertical position is detected by the drive gear 2 for raising and lowering.
This is performed by a signal from an encoder (not shown) directly connected to 1.

When the target position is reached, the inspection means 17 is scanned to inspect the shroud 1. The driving source and the position detecting method at the time of scanning are the same as those at the time of moving.

In the present invention, since the support means 14 has a chain structure, play is likely to occur in the vertical direction. Therefore, the scanning pattern is preferably not the rectangular scanning shown in FIG. 9A but the comb scanning shown in FIG. 9B.

At the time of inspection, the upper drive gear 22 is mechanically or electrically locked to minimize the slack of the support means 14 inside the inspection apparatus main body 8, and the air cylinder 23 is fixed to a certain tension. multiply.

In this state, the support means 14 is moved up and down by the lower drive gear 21.

The stroke of the air cylinder 23 is set to be larger than one half of the vertical movement stroke required for inspection, and the inspection operation can be sufficiently performed even when the upper drive gear 22 is locked. is there.

At the time of inspection, a water flow 29 is jetted out, and the ultrasonic probe 19 is pressed against the wall surface of the shroud 1.

The ejection flow rate can be set in at least two or more stages. For example, during the inspection by the ultrasonic probe 19, the flow rate is increased to improve the contact with the shroud 1, and the ultrasonic probe 19 is moved. At this time, the frictional resistance with the shroud 1 is reduced by reducing the flow rate.

The water source of the water stream 29 is reactor water, which is pumped up by a temporary pump (not shown) installed on the operation floor, pressurized, and then pushed through a water hose 27 incorporated in the support means 14. To the means 28.

After the end of the flaw detection, the device is removed in the reverse order of the installation.

FIG. 7 shows a state where the circumferential welding line 6 below the flange 5 between the intermediate body 3 and the lower body 4 is inspected.

In this case, since the inspection cannot be performed with the structure of the holding frame 18 shown in FIG. 1, the dedicated holding frame 30 is replaced with the lower end of the chain 16.

The holding frame 30 is provided with a mechanism by a link 31 which rotates toward the lower trunk side of the shroud and moves forward and backward. The rotating end of the leading link 31 has the ultrasonic probe 19 and pressing means, The link 31 provided with the ultrasonic probe 19 rotates to the lower body side and pushes to bend the support means 14 by the reaction force caused by the water jet 29 being ejected from the pressing means with the cylinder 32 in a free state. The ultrasonic probe 19 mounted on the ultrasonic probe 19 can be brought into contact with the outer surface of the lower trunk of the shroud 1 without any problem.

When storing the ultrasonic probe 19 inside the holding frame 30, the water flow 29 is stopped, and the air cylinder 32 is driven in the contracting direction to store.

In this embodiment, the water flow 29 is used as a drive source for feeding out the ultrasonic probe 19, and the air cylinder 32 is used as a drive source for storage. However, the present invention does not prevent the replacement with a ball screw or the like.

FIG. 8 shows an example in which the support means 14 is mounted upside down.

By inverting the lower part of the inspection apparatus main body 8 including the bending mechanism 13 together with the support means 14, the inspection means 17 can be brought into contact with the inner wall (not shown) of the reactor pressure vessel to perform inspection. Becomes

[0080]

According to the first aspect of the present invention, even if there is a very narrow place in the reactor pressure vessel, for example, between the jet pump riser brace and the shroud, the inspection means can be extended to near the lower part of the shroud. Can be inserted and inspected , and the supporting means is bent by the reaction force that ejected the fluid.
Access of inspection means to narrow areas
It becomes easy.

[0081]

According to the invention of claim 2 , in addition to the effect of the invention of claim 1 , the rigidity of the support means can be increased, so that the scanning and positioning of the inspection means become easy.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the rigidity of the supporting means is further increased, and the scanning and positioning of the inspection means are further facilitated.

According to the fourth aspect of the present invention, in addition to the effect of the third aspect of the present invention, the cable and the hose are restrained by the holding plate, and the followability to the movement of the chain is improved, and the variation is prevented. Handling becomes easy.

According to the fifth aspect of the present invention, the contract from the first aspect is obtained.
In addition to the effects of the invention of any one of the preceding claims ,
The inspection apparatus body itself is installed near the inspection object itself or the inspection object, and the movement of the inspection means in the circumferential direction and the vertical direction along the shroud can be performed reliably and easily.

According to the invention of claim 6 , in addition to the effect of the invention of claim 5 , scanning and positioning of the inspection means can be performed accurately.

According to the invention of claim 7, the contract from claim 1 is
In addition to the effects of the invention of any one of the preceding claims ,
At least the pressing force of the inspection means against the inspection object is large at the time of inspection and small at the time of movement, so that both reliable inspection and ease of movement can be achieved.

According to the invention of claim 8, the contract from claim 1 is obtained.
In addition to the effects of the invention of any one of the preceding claims ,
The effect that the inspection of the T-shaped corner part can be performed is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an inspection operation state in which an in-core inspection apparatus according to an embodiment of the present invention is assembled to a shroud in a reactor pressure vessel.

FIG. 2 is a perspective view showing a state immediately after assembling the in-reactor inspection apparatus according to the embodiment of the present invention to a shroud in a reactor pressure vessel.

FIG. 3 is a conceptual diagram showing an internal mechanism of an inspection device main body of the in-furnace inspection device of FIG.

FIG. 4 is a plan view of a chain element of the chain of the support means of FIG. 1;

FIG. 5 is an enlarged perspective view of the vicinity of a lower end of the in-furnace inspection apparatus of FIG. 1;

FIG. 6 is an elevational view showing a shape of a shroud employed in the reactor pressure vessel in a left half display, and FIG.
(B) is a figure which showed the shroud which adopted the Example of 3rd, and the shroud of another shape, respectively.

FIG. 7 is an elevation view near the lower end of an in-furnace inspection apparatus according to another embodiment of the present invention.

FIG. 8 is a perspective view of an embodiment of the present invention, showing an inspection operation state in which an in-core inspection device for inspecting an inner wall surface of a reactor pressure vessel is attached to a shroud in the reactor pressure vessel.

9A and 9B are diagrams showing a scanning pattern when the inspection means according to the embodiment of the present invention is used for inspection, wherein FIG. 9A shows a rectangular pattern and FIG. 9B shows a comb pattern. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Shroud, 2 ... Upper trunk, 3 ... Middle trunk, 4 ... Lower trunk, 5 ... Flange, 6 ... Circumferential welding line, 7 ... Shroud support, 8 ... Inspection apparatus main body, 9 ... Shroud upper flange, 10 ... Drive wheel , 11: Guide wheel, 12: Encoder, 13: Bending mechanism, 14: Support means, 15, 23, 3
2 ... air cylinder, 16 ... chain, 17 ... inspection means, 18 ... holding frame, 19 ... ultrasonic probe, 20 ...
TV camera, 21: drive gear for lifting and lowering, 22: drive gear,
Reference numeral 24: air gap, 25: ultrasonic signal cable, 26: video signal cable, 27: water hose, 28: pressing means, 2
9 ... water flow, 30 ... holding frame, 31 ... link, 33 ...
Drive motor, 34: baffle plate, 35: holding plate.

──────────────────────────────────────────────────続 き Continued on the front page (72) Akira Akasu 3-2-1, Sachimachi, Hitachi City, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (56) References JP-A-4-128649 (JP, A) 4-16409 (JP, A) JP-A-1-132960 (JP, A) JP-A-8-29397 (JP, A) JP-A-60-191920 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (8)

(57) [Claims] 1. An in-core inspection apparatus for a nuclear reactor in which an inspection means supported by a support means is inserted into a reactor pressure vessel and the inspection means is pressed against an inspection object by a press means. A flexible frame that is bendable over its entire length, comprising a holding frame having the flexible structure to which the inspection means is attached, and supported by a lower end portion of the support means as the pressing means. comprises ejection means of the fluid ejection reaction force of the fluid and the pressing force of said test means further comprises a bending mechanism for bending the portion of the upper of the support means than the lower end portion to the inspected object side And a means for ejecting a fluid to the flexible structure,
Inspection of a soft structure by the jet reaction force of the fluid jetting means
An in-reactor inspection apparatus for a nuclear reactor, which is equipped so as to be directed toward an object . 2. The flexible structure according to claim 1 , wherein:
An in-reactor inspection apparatus for a nuclear reactor, comprising a configuration in which chains whose axis is oriented in a circumferential direction of a reactor pressure vessel are arranged in parallel at intervals in the circumferential direction. 3. The in-reactor inspection apparatus according to claim 2 , wherein the parallel chains are connected by a holding plate to maintain a constant parallel interval. 4. The method according to claim 3 , wherein said holding plate surrounds said holding plate.
An in-core inspection system for a nuclear reactor, comprising a cable to an inspection unit and a hose to a fluid ejection unit along a chain. 5. An inspection apparatus main body removably mounted on an upper part of a shroud in a reactor pressure vessel according to any one of claims 1 to 4, and the inspection apparatus main body is arranged along the shroud. An in-core inspection apparatus for a nuclear reactor, comprising: a circumferential moving means for moving in a circumferential direction; and an elevating means for vertically moving a supporting means from the inspection apparatus main body. 6. The apparatus according to claim 5 , wherein said support means is provided with a tension applying means for applying tension via a movable chain sprocket, and a moving stroke of said chain sprocket is １ ／ of a scanning stroke of said inspection means. An in-core inspection apparatus for a nuclear reactor, characterized by the above. 7. A reactor according to claim 1 , further comprising means for changing the energy of the fluid from the means for ejecting the fluid in at least two levels. Inspection equipment. 8. A holding frame according to any one of claims 1 to 7, wherein the holding frame includes a link which rotates in the direction of the object to be inspected and is capable of moving back and forth. An in-core inspection device for a nuclear reactor, comprising: