CA1205584A - Method and apparatus for inspection of a pressure tube in a pressure tube type nuclear reactor - Google Patents
Method and apparatus for inspection of a pressure tube in a pressure tube type nuclear reactorInfo
- Publication number
- CA1205584A CA1205584A CA000443964A CA443964A CA1205584A CA 1205584 A CA1205584 A CA 1205584A CA 000443964 A CA000443964 A CA 000443964A CA 443964 A CA443964 A CA 443964A CA 1205584 A CA1205584 A CA 1205584A
- Authority
- CA
- Canada
- Prior art keywords
- pressure tube
- inspection apparatus
- inspection
- sensor
- driving device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C17/00—Monitoring; Testing ; Maintaining
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02872—Pressure
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
METHOD AND APPARATUS FOR INSPECTION
OF A PRESSURE TUBE IN A PRESSURE TUBE TYPE NUCLEAR REACTOR
ABSTRACT OF THE DISCLOSURE
A new apparatus and method for inspecting the pressure tube of a pressure tube type nuclear reactor, utilizing an inspection apparatus which is a unitary structure of a sensor, its driving device and a securing mechanism. The unitary structure is miniaturized entirely for ready insertion in the pressure tube to be inspected. The inspection apparatus is inserted into the pressure tube by means of a refueling machine provided generally on the nuclear reactor for insertion and removal of the fuel assembly into and out of the pressure tube.
OF A PRESSURE TUBE IN A PRESSURE TUBE TYPE NUCLEAR REACTOR
ABSTRACT OF THE DISCLOSURE
A new apparatus and method for inspecting the pressure tube of a pressure tube type nuclear reactor, utilizing an inspection apparatus which is a unitary structure of a sensor, its driving device and a securing mechanism. The unitary structure is miniaturized entirely for ready insertion in the pressure tube to be inspected. The inspection apparatus is inserted into the pressure tube by means of a refueling machine provided generally on the nuclear reactor for insertion and removal of the fuel assembly into and out of the pressure tube.
Description
5~
The present invention relates in general to the inspection of a pressure tube in a pressure tube type nuclear reactor, and more particularly to a method and apparatus for inspecting, for example, flaws or defects of the pressure tube. In the present invention, an inspection apparatus is so shaped that it is removably and displaceably inserted into the pressure tube through remote control by means of a refueling machine for inspection.
The present invention will be illustrated by way of the accompanying drawings, in which:-Figures 1 and 2 are explanatory views of the con-ventional "external installation system" and "refueling machine combined system", respectively;
Figures 3A, 3B, 3C and 3D are explanatory views, showing the steps according to the method of the present invention; and Figure 4 is an el.evation of an inspection apparatus according to the present invention, showing the inspection apparatus inserted into a pressure tube for inspection.
A pressure tube constituting the core of a pres-sure tube type nuclear reactor is subjected to an in-service inspection (ISI) according to the rules. However, since the pressure tube to be inspected is exposed to a high radiation environment both internall.y and peripherall.y, the inspection is carried out on an automatic remote controller so as to protect the inspection personnel at the time of in-service inspection.
For structural restriction, the pressure tube type nuclear reactor cannot have a rail or the like which is necessary for bringing an inspection apparatus close to the a~
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lZ0558~
pressure tube. ~nder the restriction circumstances as des-cribed, the pressure tube inspection has been effected on either of the following two systems according to the prior art, which will be described with reference to Figures 1 and
The present invention relates in general to the inspection of a pressure tube in a pressure tube type nuclear reactor, and more particularly to a method and apparatus for inspecting, for example, flaws or defects of the pressure tube. In the present invention, an inspection apparatus is so shaped that it is removably and displaceably inserted into the pressure tube through remote control by means of a refueling machine for inspection.
The present invention will be illustrated by way of the accompanying drawings, in which:-Figures 1 and 2 are explanatory views of the con-ventional "external installation system" and "refueling machine combined system", respectively;
Figures 3A, 3B, 3C and 3D are explanatory views, showing the steps according to the method of the present invention; and Figure 4 is an el.evation of an inspection apparatus according to the present invention, showing the inspection apparatus inserted into a pressure tube for inspection.
A pressure tube constituting the core of a pres-sure tube type nuclear reactor is subjected to an in-service inspection (ISI) according to the rules. However, since the pressure tube to be inspected is exposed to a high radiation environment both internall.y and peripherall.y, the inspection is carried out on an automatic remote controller so as to protect the inspection personnel at the time of in-service inspection.
For structural restriction, the pressure tube type nuclear reactor cannot have a rail or the like which is necessary for bringing an inspection apparatus close to the a~
~;' i,, ~g~
lZ0558~
pressure tube. ~nder the restriction circumstances as des-cribed, the pressure tube inspection has been effected on either of the following two systems according to the prior art, which will be described with reference to Figures 1 and
2.
The first is a system (hereinafter referred to as "external installation system" for clarification purposes) shown in Figure 1 wherein an inspection apparatus has a sensor 2 for detecting various defects of a pressure tube 1, a driving device 3 for the sensor 2, a holder or carriage 4 of the driving device and a positioning device 6, and is assembled by hand at the position near the pressure tube 1 before inspection is carried out. The sensor 2 is mounted on the top of a supporting rod 5 and inserted within the pressure tube 1 for inspection through a remote control. After the inspection is finished, the apparatus is removed out of the pressure tube and then disassembled by hand. In Figure 1 of the drawing, reference numeral 9 denotes a seal plug for sealing a reactor coolant in the pressure tube, and reference numeral 10 a fuel assembly.
The external installation system described above provides an advantage that inspection personnel is protected from exposure at the time of inspection only, but has at the same time serious problems such that an exposure at the time of assembling and disassembling of the apparatus is unavoidable, and the assembling/disassembling at each inspec-tion involves a troublesome and timeconsuming operation.
Moreover, a reactor coolant(water) in the pressure tube to be inspected must be removed at the time of inspection unless the inspection apparatus is configured entirely to have a watertight structure, which however is cost-consuming.
In order to accomplish the removal of the coolant from the pressure tube, a part of coolant in an inlet pipe and outlet pipe must be frozen with, for example, liquid nitrogen to
The first is a system (hereinafter referred to as "external installation system" for clarification purposes) shown in Figure 1 wherein an inspection apparatus has a sensor 2 for detecting various defects of a pressure tube 1, a driving device 3 for the sensor 2, a holder or carriage 4 of the driving device and a positioning device 6, and is assembled by hand at the position near the pressure tube 1 before inspection is carried out. The sensor 2 is mounted on the top of a supporting rod 5 and inserted within the pressure tube 1 for inspection through a remote control. After the inspection is finished, the apparatus is removed out of the pressure tube and then disassembled by hand. In Figure 1 of the drawing, reference numeral 9 denotes a seal plug for sealing a reactor coolant in the pressure tube, and reference numeral 10 a fuel assembly.
The external installation system described above provides an advantage that inspection personnel is protected from exposure at the time of inspection only, but has at the same time serious problems such that an exposure at the time of assembling and disassembling of the apparatus is unavoidable, and the assembling/disassembling at each inspec-tion involves a troublesome and timeconsuming operation.
Moreover, a reactor coolant(water) in the pressure tube to be inspected must be removed at the time of inspection unless the inspection apparatus is configured entirely to have a watertight structure, which however is cost-consuming.
In order to accomplish the removal of the coolant from the pressure tube, a part of coolant in an inlet pipe and outlet pipe must be frozen with, for example, liquid nitrogen to
- 3 -120SS8~
form an ice plug for working as a valve substitutionally since there is no valve provided at the inlet and the outlet of each pressure tube, but provision of ice plug is trouble-some. Furthermore, it is difficult to install a plurality of inspection apparatus for space limitation, and thus a considerably long time will be required for the inspection of multiple pressure tubes.
The second system in the prior art is a system shown in Figure 2 (hereinafter referred to as "reflueling machine combined system" for the purpose of clarification), in which a driving device 8 of a refueling machine 7 is utilized not for the purpose of refueling but for the purpose of insertion of the sensor 2 into the pressure tube for inspection.
Specifically, the sensor 2 is mounted on the supporting rod 5 thorugh the driving device 8 of ~he refueling machine 7 which is generally provided on a nuclear reactor for loading and unloading the fuel assembly 10 into and from the pressure tube. The sensor 2 mounted on the driving device 8 is then inserted by remote control into the pressure tube for inspec-tion.
The refueling machine combined system utilizes the refueling machine as described above, and the operation for assembling and disassembling the apparatus, which is required in the first-mentioned external installation system, is not required.
Thus, the problem of exposure of the inspection personnel can be settled, and the refueling machine which is of water-12C)558~
tight structure requires no removal of water in the pressure tube. However, the refueling machine is exclusively used while the pressure tube is subjected to inspection, therefore a considerably long time also will be required for the inspection particularly when a number of pressure tubes are inspected.
The present invention removes the drawbacks pre-vailing on the prior art systems.
The present invention also provides a system which can minimize a possibility of exposure of the inspection personnel in in-service inspection of the reactor pressure tube and ensure working efficiency with a minimum time for inspection.
The present invention again provides an inspection apparatus for a pressure tube of the nuclear reactor, in which the inspection apparatus has a sensor and a driving device thereof in a unitary structure adaptable into the pressure tube.
The invention also provides an inspection method for pressure tube effective enough to minimize a possibility of exposure of the inspection personnel at the time of in-service inspection of the reactor pressure tube and also to ensure working efficiency with less time for inspection.
120558~
Briefly, the present invention provides a new apparatus and method for inspecting the pressure tube, utilizing an inspection apparatus which is a unitary structure of a sensor, its driving device and a mechanism for securing the sensor and the driving device. The unitary structure is miniaturized entirely for ready insertion in the pressure tube to be inspected. In the present invention, the inspection apparatus is inserted into the pressure tube by means of a refueling machine provided generally on a pressure tube type nuclear reactor for insertion and removal of the fuel assembly into and out of the pressure tube.
The inspeci~on apparatus according to the present inven-tion comprises a sensor means, removably and slidably located within the pressure tube, for detecting defects of the pressure tube, a driving means for rotational and vertical or longitudi-nal displacement of the sensor means within the pressure tube, securing mechanism, releasably connected to an open end of the pressure tube, for holding the sensor means and the driving means in position within the pressure tube, and a sealing device for enclosing a reactor coolant in the pressure tube.
In the inspection method according to the present inven-tion, the inspection apparatus of the structure as described above is inserted into the pressure tube to be inspected through remote control by means of the refueling machine, and held in position within the pressure tube, which is then inspected throuyh remote control. When the inspection l~OS584 is finished, the inspection apparatus is removed from the pressure tube by means of the refueling machine.
Upon analyzing the above-mentioned prior art from various angles and also examining measures available for settling defects on the prior art, the inventors have reached the conslusion that a miniature sensor of the inspecting apparatus is obtainable hitherto and is ready for inserting within the pressure tube accordingly, however, the driving device and holding member of the inspection apparatus are framed to a larger size, which is problematical in this connection.
Further examinations have obtained the following results:
(1) If the refueling machine 7 is utilized, the positioning device 6 in the "external installation system" will not be required, and thus the device 6 can be omitted from the inspection apparatus.
(2) If the inspection apparatus itself can be inserted and fixed entirely within the pressure tube 1, then a sensor driving stroke can be shortened to the same length as an inspecting range, as a sensor 2 is located near the portion to be inspected.
(3) The holding member 4 of the inspection apparatus occupies a considerable area in the external installation system, however, if the inspeciton apparatus can be inserted full within the pressure tube, the pressure tube rnay function as the holding member of the inspection apparatus, therefore the holding member can be simplified.
form an ice plug for working as a valve substitutionally since there is no valve provided at the inlet and the outlet of each pressure tube, but provision of ice plug is trouble-some. Furthermore, it is difficult to install a plurality of inspection apparatus for space limitation, and thus a considerably long time will be required for the inspection of multiple pressure tubes.
The second system in the prior art is a system shown in Figure 2 (hereinafter referred to as "reflueling machine combined system" for the purpose of clarification), in which a driving device 8 of a refueling machine 7 is utilized not for the purpose of refueling but for the purpose of insertion of the sensor 2 into the pressure tube for inspection.
Specifically, the sensor 2 is mounted on the supporting rod 5 thorugh the driving device 8 of ~he refueling machine 7 which is generally provided on a nuclear reactor for loading and unloading the fuel assembly 10 into and from the pressure tube. The sensor 2 mounted on the driving device 8 is then inserted by remote control into the pressure tube for inspec-tion.
The refueling machine combined system utilizes the refueling machine as described above, and the operation for assembling and disassembling the apparatus, which is required in the first-mentioned external installation system, is not required.
Thus, the problem of exposure of the inspection personnel can be settled, and the refueling machine which is of water-12C)558~
tight structure requires no removal of water in the pressure tube. However, the refueling machine is exclusively used while the pressure tube is subjected to inspection, therefore a considerably long time also will be required for the inspection particularly when a number of pressure tubes are inspected.
The present invention removes the drawbacks pre-vailing on the prior art systems.
The present invention also provides a system which can minimize a possibility of exposure of the inspection personnel in in-service inspection of the reactor pressure tube and ensure working efficiency with a minimum time for inspection.
The present invention again provides an inspection apparatus for a pressure tube of the nuclear reactor, in which the inspection apparatus has a sensor and a driving device thereof in a unitary structure adaptable into the pressure tube.
The invention also provides an inspection method for pressure tube effective enough to minimize a possibility of exposure of the inspection personnel at the time of in-service inspection of the reactor pressure tube and also to ensure working efficiency with less time for inspection.
120558~
Briefly, the present invention provides a new apparatus and method for inspecting the pressure tube, utilizing an inspection apparatus which is a unitary structure of a sensor, its driving device and a mechanism for securing the sensor and the driving device. The unitary structure is miniaturized entirely for ready insertion in the pressure tube to be inspected. In the present invention, the inspection apparatus is inserted into the pressure tube by means of a refueling machine provided generally on a pressure tube type nuclear reactor for insertion and removal of the fuel assembly into and out of the pressure tube.
The inspeci~on apparatus according to the present inven-tion comprises a sensor means, removably and slidably located within the pressure tube, for detecting defects of the pressure tube, a driving means for rotational and vertical or longitudi-nal displacement of the sensor means within the pressure tube, securing mechanism, releasably connected to an open end of the pressure tube, for holding the sensor means and the driving means in position within the pressure tube, and a sealing device for enclosing a reactor coolant in the pressure tube.
In the inspection method according to the present inven-tion, the inspection apparatus of the structure as described above is inserted into the pressure tube to be inspected through remote control by means of the refueling machine, and held in position within the pressure tube, which is then inspected throuyh remote control. When the inspection l~OS584 is finished, the inspection apparatus is removed from the pressure tube by means of the refueling machine.
Upon analyzing the above-mentioned prior art from various angles and also examining measures available for settling defects on the prior art, the inventors have reached the conslusion that a miniature sensor of the inspecting apparatus is obtainable hitherto and is ready for inserting within the pressure tube accordingly, however, the driving device and holding member of the inspection apparatus are framed to a larger size, which is problematical in this connection.
Further examinations have obtained the following results:
(1) If the refueling machine 7 is utilized, the positioning device 6 in the "external installation system" will not be required, and thus the device 6 can be omitted from the inspection apparatus.
(2) If the inspection apparatus itself can be inserted and fixed entirely within the pressure tube 1, then a sensor driving stroke can be shortened to the same length as an inspecting range, as a sensor 2 is located near the portion to be inspected.
(3) The holding member 4 of the inspection apparatus occupies a considerable area in the external installation system, however, if the inspeciton apparatus can be inserted full within the pressure tube, the pressure tube rnay function as the holding member of the inspection apparatus, therefore the holding member can be simplified.
(4) The inspection apparatus thus miniaturized and lightweight-:lZ05589~
ed entirely may entail only a motor of several ten Wattsinstead of several hundred Watts for the driving power source, and therefore the motor can be replaced by that of miniature which can be arranged within the pressure tube.
The invention has been contrived according to the analysis and examinations mentioned above.
A preferred embodiment of the present invention will be made with reference to the accompanying drawings.
.~
lZOSS84 DETAILED DESCRIPTION OF THE INVENTION
Referring first to Figure 4 which shows the structure of an inspection apparatus 11 embodying the present invention, the apparatus 11 is configured to have a shape and size for insertion completely into the pressure tube 1. The inspection apparatus 11 has a sensor indicated generally by reference numeral 15 including, for example, an ultrasonic test instrument for investigating flaws or defects in the pressure tube wall, a TV camera for observation of the state of the pressure tube inner surface, and a bore measuring apparatus for measuring the inner diameter of the pressure tube to investigate the "creep" which is an increment in the inner diameter due to irradiation. Further, the apparatus 11 has a driving mechanism constituted of a vertical driving device 16 for moving the sensor vertically within and along the length of the pressure tube and a rotational driving device 17 for rotationally moving same within the pressure tube, a securing mechanism 18 for holding the inspection apparatus in position within the pressure tube 1, and a sealing unit 20 for sealing a reactor cooling water in the pressure tube 1.
The securing mechanism 18 is readily releasably engaged with the pressure tube 1, which may becon5tituted by a combina-tion of, for example, ball and latch. The driving mec.hanism 16, 17 is firmly held on the securing mechanism 18 to movably support the sensor 15. The vertical driving device 16 is -- g _ 12~)5584 formed of a pinion 25 and rack 26 in the illustrated embodiment, which however can be modified to a wire driving structure.
Three pieces of rotary ball type guides 19 are provided on the circumference of a moving part of the inspection apparatus 11, in which the sensor 15 is received. These guides 19 are in contact with the inner surface of the pressure tube 1 to position the moving part at the center at all times, and thus guide it for a smooth vertical movement and a rotational operation within the pressure tube 1.
Preferably, one of the three guides 19 is biased outwardly by a spring (not shown) so as to maintain the three guides 19 in contact with the inner surface of the pressure tube 1 irrespective of any slight change in the inner diameter of the pressure tube.
The inspection apparatus 11 is handled by the refueling machine so that it is inserted into and removed from the pressure tube 1 through remote control. Then, a connector 14 mounted on the end of a signal transmission cable 13 is releasably connected with the inspection apparatus 11 by means of a manipulator 22 of the refueling machine 7, and the inspection apparatus 11 is operated through remote control by a control pannel 12 connected to the signal trans-mission cable 13. The connector 14 may be releasably engaged with the inspection apparatus 11 by the use of, for example, a ball and latch mechanism.
Operational steps of the inspection apparatus 11 will be described with reference to Figures 3A to 3D.
120~5~34 (i) Withdraw the fuel assembly:
First, the fuel assembly 10 in the pressure tube to be inspected is withdrawn by means of the refueling machine 7, and the seal plug 9 for sealing the reactor coolant in the pressure tube l is mounted~
(ii) Install the apparatus in the refueling machine:
The inspection apparatus 11 is then hang down by a crane 23 and installed in the refueling machine 7 (Fig.
3A)-(iii) Couple the refueling machine to the pressure tube:
Next, the refueling machine 7 is driven to move underthe pressure tube 1 to be inspected and positioned duly (Fig. 3B), then an upper end of the refueling machine 7 is coupled to a lower end of the pressure tube 1 so that the reactor coolant will not leak out of the pressure tube, and the seal plug 9 is demounted. (A demounting procedure of the seal plug 9 is not particularly illustrated, however, its function is included in the refueling machine 7.) (iv) Insert the apparatus into the pressure tube:
urther the inspection apparatus 11 is inserted within the pressure tube 1 (Fig. 3C), and the inspection apparatus 11 is fixed in the pressure tube 1 through the securing mechanism 18 ~Fig. 4) of the inspection apparatus 11. In this case, the reactor coolant is sealed by the sealing unit 20 of the inspeciton apparatus 11.
(v) Connect the connector to the apparatus:
Then, the refueling machine 7 is displaced somewhat to align the manipulator 22 with the pressure tube 1 to lZO$5~3~
be inspected, and the connector 14 is connected to the inspec-tion apparatus 11 by the manipulator 22 (Fig. 3D). The manipulator 22 and the refueling machine 7 may be removed from the inspection apparatus after connecting the connector 14 to the inspection apparatus 11. These operations can be effected all through remote control by the refueling machine 7 and the manipulator 22.
(vi) Inspection:
Everything is now ready for inspection, and as shown in Fig. 4, the sensor 15 is moved to the spot for inspection by operating the vertical driving device 16 and the rotational driving device 17 through remote control from the control panel 12. In this case the guides 19 function for operating the inspection apparatus 11 smoothly in the pressure tube, as described hereinabove. When the inspection is finished, the above procedure is reversed to withdraw the inspection apparatus 11 from the pressure tube.
In the above embodiment a signal is transmitted between the inspection apparatus 11 and the control panel 12 by way of the signal transmission cable 13, however, a wi.reless transmission system can be employed, if desired.
According to the inspection method of the present inven-tion, the operation fox assembling and removing the inspection apparatus near the reactor core is not required before and after inspection, and thus an exposure of the inspection personnel can be decreased to 1/10 or below as compared with the conventional "external installation system". Further, ~2~S58~
it is not necessary to withdraw coolant in the pressure tube to be inspected, which may avoid a troublesome preparation for the inspection. Furthe, the refueling machine can be used freely after the inspection apparatus is inserted in the pressure tube to be inspected, and the other inspection apparatus, if additionally prepa.red, can be used for inspec-tion of other pressure tubes simultaneously while one pressure tube is subjected to inspection, therefore the time required for inspection can be shortened considerably as compared with the conventional "refueling machine combined system".
Although the present invention has been described with reference to the preferred embodiment thereof, many modifica-tions and alterations can be made within the scope of the appended claims.
ed entirely may entail only a motor of several ten Wattsinstead of several hundred Watts for the driving power source, and therefore the motor can be replaced by that of miniature which can be arranged within the pressure tube.
The invention has been contrived according to the analysis and examinations mentioned above.
A preferred embodiment of the present invention will be made with reference to the accompanying drawings.
.~
lZOSS84 DETAILED DESCRIPTION OF THE INVENTION
Referring first to Figure 4 which shows the structure of an inspection apparatus 11 embodying the present invention, the apparatus 11 is configured to have a shape and size for insertion completely into the pressure tube 1. The inspection apparatus 11 has a sensor indicated generally by reference numeral 15 including, for example, an ultrasonic test instrument for investigating flaws or defects in the pressure tube wall, a TV camera for observation of the state of the pressure tube inner surface, and a bore measuring apparatus for measuring the inner diameter of the pressure tube to investigate the "creep" which is an increment in the inner diameter due to irradiation. Further, the apparatus 11 has a driving mechanism constituted of a vertical driving device 16 for moving the sensor vertically within and along the length of the pressure tube and a rotational driving device 17 for rotationally moving same within the pressure tube, a securing mechanism 18 for holding the inspection apparatus in position within the pressure tube 1, and a sealing unit 20 for sealing a reactor cooling water in the pressure tube 1.
The securing mechanism 18 is readily releasably engaged with the pressure tube 1, which may becon5tituted by a combina-tion of, for example, ball and latch. The driving mec.hanism 16, 17 is firmly held on the securing mechanism 18 to movably support the sensor 15. The vertical driving device 16 is -- g _ 12~)5584 formed of a pinion 25 and rack 26 in the illustrated embodiment, which however can be modified to a wire driving structure.
Three pieces of rotary ball type guides 19 are provided on the circumference of a moving part of the inspection apparatus 11, in which the sensor 15 is received. These guides 19 are in contact with the inner surface of the pressure tube 1 to position the moving part at the center at all times, and thus guide it for a smooth vertical movement and a rotational operation within the pressure tube 1.
Preferably, one of the three guides 19 is biased outwardly by a spring (not shown) so as to maintain the three guides 19 in contact with the inner surface of the pressure tube 1 irrespective of any slight change in the inner diameter of the pressure tube.
The inspection apparatus 11 is handled by the refueling machine so that it is inserted into and removed from the pressure tube 1 through remote control. Then, a connector 14 mounted on the end of a signal transmission cable 13 is releasably connected with the inspection apparatus 11 by means of a manipulator 22 of the refueling machine 7, and the inspection apparatus 11 is operated through remote control by a control pannel 12 connected to the signal trans-mission cable 13. The connector 14 may be releasably engaged with the inspection apparatus 11 by the use of, for example, a ball and latch mechanism.
Operational steps of the inspection apparatus 11 will be described with reference to Figures 3A to 3D.
120~5~34 (i) Withdraw the fuel assembly:
First, the fuel assembly 10 in the pressure tube to be inspected is withdrawn by means of the refueling machine 7, and the seal plug 9 for sealing the reactor coolant in the pressure tube l is mounted~
(ii) Install the apparatus in the refueling machine:
The inspection apparatus 11 is then hang down by a crane 23 and installed in the refueling machine 7 (Fig.
3A)-(iii) Couple the refueling machine to the pressure tube:
Next, the refueling machine 7 is driven to move underthe pressure tube 1 to be inspected and positioned duly (Fig. 3B), then an upper end of the refueling machine 7 is coupled to a lower end of the pressure tube 1 so that the reactor coolant will not leak out of the pressure tube, and the seal plug 9 is demounted. (A demounting procedure of the seal plug 9 is not particularly illustrated, however, its function is included in the refueling machine 7.) (iv) Insert the apparatus into the pressure tube:
urther the inspection apparatus 11 is inserted within the pressure tube 1 (Fig. 3C), and the inspection apparatus 11 is fixed in the pressure tube 1 through the securing mechanism 18 ~Fig. 4) of the inspection apparatus 11. In this case, the reactor coolant is sealed by the sealing unit 20 of the inspeciton apparatus 11.
(v) Connect the connector to the apparatus:
Then, the refueling machine 7 is displaced somewhat to align the manipulator 22 with the pressure tube 1 to lZO$5~3~
be inspected, and the connector 14 is connected to the inspec-tion apparatus 11 by the manipulator 22 (Fig. 3D). The manipulator 22 and the refueling machine 7 may be removed from the inspection apparatus after connecting the connector 14 to the inspection apparatus 11. These operations can be effected all through remote control by the refueling machine 7 and the manipulator 22.
(vi) Inspection:
Everything is now ready for inspection, and as shown in Fig. 4, the sensor 15 is moved to the spot for inspection by operating the vertical driving device 16 and the rotational driving device 17 through remote control from the control panel 12. In this case the guides 19 function for operating the inspection apparatus 11 smoothly in the pressure tube, as described hereinabove. When the inspection is finished, the above procedure is reversed to withdraw the inspection apparatus 11 from the pressure tube.
In the above embodiment a signal is transmitted between the inspection apparatus 11 and the control panel 12 by way of the signal transmission cable 13, however, a wi.reless transmission system can be employed, if desired.
According to the inspection method of the present inven-tion, the operation fox assembling and removing the inspection apparatus near the reactor core is not required before and after inspection, and thus an exposure of the inspection personnel can be decreased to 1/10 or below as compared with the conventional "external installation system". Further, ~2~S58~
it is not necessary to withdraw coolant in the pressure tube to be inspected, which may avoid a troublesome preparation for the inspection. Furthe, the refueling machine can be used freely after the inspection apparatus is inserted in the pressure tube to be inspected, and the other inspection apparatus, if additionally prepa.red, can be used for inspec-tion of other pressure tubes simultaneously while one pressure tube is subjected to inspection, therefore the time required for inspection can be shortened considerably as compared with the conventional "refueling machine combined system".
Although the present invention has been described with reference to the preferred embodiment thereof, many modifica-tions and alterations can be made within the scope of the appended claims.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of inspecting a pressure tube of a pressure tube type nuclear reactor having a refueling machine for loading and unloading a nuclear fuel assembly in and from the pressure tube, comprising:
providing an inspection apparatus configured to be completely adaptable within said pressure tube;
said inspection apparatus having a securing mechanism for securing said inspection apparatus entirely in position within said pressure tube, a sensor for inspecting the pressure tube, a driving device for moving said sensor within said pressure tube, and a sealing unit for sealing a reactor coolant in said pressure tube, inserting said inspection apparatus entirely in said pressure tube to be inspected through remote control by means of said refueling machine;
securing said inspection apparatus in said pressure tube;
driving said driving device through remote control to move said sensor to complete inspection of said pressure tube; and withdrawing said inspection apparatus from said pressure tube through remote control by means of said refueling machine.
providing an inspection apparatus configured to be completely adaptable within said pressure tube;
said inspection apparatus having a securing mechanism for securing said inspection apparatus entirely in position within said pressure tube, a sensor for inspecting the pressure tube, a driving device for moving said sensor within said pressure tube, and a sealing unit for sealing a reactor coolant in said pressure tube, inserting said inspection apparatus entirely in said pressure tube to be inspected through remote control by means of said refueling machine;
securing said inspection apparatus in said pressure tube;
driving said driving device through remote control to move said sensor to complete inspection of said pressure tube; and withdrawing said inspection apparatus from said pressure tube through remote control by means of said refueling machine.
2. The method of inspecting the pressure tube according to claim 1, wherein said sensor is moved vertically and rotation-ally within said pressure tube by means of said driving device.
3. The method of inspecting the pressure tube according to claim 1, wherein the refueling machine is removed from the inspection apparatus after securing the inspection apparatus in the pressure tube.
4. An inspection apparatus for a pressure tube of a pressure tube type nuclear reactor provided with a refueling machine for loading and unloading a nuclear fuel assembly in and from the pressure tube, comprising:
sensor means, removably and slidably located within said pressure tube, for detecting defects of said pressure tube;
driving means for displacement of said sensor means within said pressure tube;
securing mechanism, releasably connected to said pressure tube, for securing said sensor means and said driving means in position within said pressure tube; and a sealing unit for sealing a reactor coolant in said pressure tube.
sensor means, removably and slidably located within said pressure tube, for detecting defects of said pressure tube;
driving means for displacement of said sensor means within said pressure tube;
securing mechanism, releasably connected to said pressure tube, for securing said sensor means and said driving means in position within said pressure tube; and a sealing unit for sealing a reactor coolant in said pressure tube.
5. The inspection apparatus according to claim 4, wherein said driving means has a first driving device for a rotational movement of said sensor means, and a second driving device for a vertical movement of said sensor means within said pressure tube.
6. The inspection apparatus according to claim 4, wherein said sensor means includes a TV camera for observation of the inner surface of said pressure tube, an ultrasonic test instrument for investigating defects on said pressure tube and/or an inner diameter measurement instrument for measuring the inner diameter of said pressure tube.
7. The inspection apparatus according to claim 4, wherein said securing mechanism includes a ball and latch assembly.
8. The inspection apparatus according to claim 4, wherein said driving means is fixed to said securing mechanism to movably support said sensor means.
9. The inspection apparatus according to claim 4, wherein said first driving device has a combination of a pinion and a rack.
10. The inspection apparatus according to claim 4, wherein three ball guides are provided on the circumference of said sensor means such that said ball guides are in contact with the inner surface of said pressure tube, thereby positioning said sensor means at the center within said pressure tube and facilitating smooth vertical and rotational movement of said sensor means within said pressure tube.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57229092A JPS59116540A (en) | 1982-12-24 | 1982-12-24 | Method for checking pressure pipe of atomic reactor |
| JP57-229092 | 1982-12-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1205584A true CA1205584A (en) | 1986-06-03 |
Family
ID=16886622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443964A Expired CA1205584A (en) | 1982-12-24 | 1983-12-21 | Method and apparatus for inspection of a pressure tube in a pressure tube type nuclear reactor |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS59116540A (en) |
| CA (1) | CA1205584A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61296263A (en) * | 1985-06-25 | 1986-12-27 | Mitsubishi Heavy Ind Ltd | Apparatus for controlling eddy current flaw detection |
-
1982
- 1982-12-24 JP JP57229092A patent/JPS59116540A/en active Granted
-
1983
- 1983-12-21 CA CA000443964A patent/CA1205584A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0143280B2 (en) | 1989-09-19 |
| JPS59116540A (en) | 1984-07-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |