Patent Publication Number: US-2023138837-A1

Title: Apparatus and method of removing foreign substances from steam generator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2021-0150444, filed on Nov. 4, 2021, the entire contents of which are incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to an apparatus and method of removing foreign substances from a steam generator and, more particularly, to an apparatus for removing foreign substances located on a bundle of heating tubes of a steam generator used in a nuclear power plant, and a method of removing foreign substances located on a bundle of heating tubes using the same. 
     2. Description of the Background Art 
     Referring to the Background art described in Korean Patent Registration No. 10-1086344, in general, a steam generator in a nuclear power plant is one of the most important facilities for generating steam required to produce electric power from a steam turbine and a power generator. 
     Specifically, a plurality of heating tubes formed in a bundle are disposed in the steam generator. The heating tube provides a heat exchange function between primary system water containing radioactivity and secondary system water turning a turbine, and serves to separate the primary system water and the secondary system water from each other. 
     Steam is generated as follows. The primary system water heated while passing through a nuclear reactor flows through a path in the heating tube of the steam generator. The secondary system water supplied to the outside of the heating tube comes into contact with an external wall of the heating tube. Thus, heat exchange is performed between the primary system water and the secondary system water through a tube wall of the heating tube. Then, the primary system water flows back toward the nuclear reactor through a path of a closed circuit, and circulates through the nuclear reactor, and the secondary system water is converted to steam. 
     That is, radioactive water (i.e., the primary system water) with high temperature and pressure flows through the inside of the heating tube, and nonradioactive water (i.e., the secondary system water) flows around the outside of the heating tube, with a wall of the heating tube disposed therebetween. Thus, if the heating tube is damaged, the radioactive water (i.e., the primary system water) flowing through the heating tube may leak out of the heating tube and be mixed with the nonradioactive water (i.e., the secondary system water) and may generate a radioactively contaminated mixed water. Thus, radioactive contamination may occur throughout a space to which steam converted from the nonradioactive water (i.e., the secondary system water) is provided. Accordingly, it is most important to ensure sealing reliability of heating tubes in various operations in a nuclear power plant. 
       FIG.  1    is a cross-sectional view illustrating a conventional steam generator,  FIG.  2    is a front cross-sectional view illustrating the steam generator of  FIG.  1   , and  FIG.  3    is a cross-sectional view schematically illustrating an operational principle of the steam generator. Referring to these drawings, the steam generator  10  includes an inlet nozzle  1  into which primary system water flows, a heating tube  3  into which the primary system water fed through the inlet nozzle  1  flows and is heat-exchanged with secondary system water introduced into the steam generator, and an outlet nozzle  5  out of which the primary system water heat-exchanged with the secondary system water in the heating tube is discharged toward a nuclear reactor. The heating tube  3  is mounted on a tube sheet  4  so as to be supported by tube support plates  6  at regular vertical intervals. A flow distribution baffle  8  shaped like a doughnut plate is installed between the lowest tube support plate  6  and the tube sheet  4  so as to support the heating tube  3 . The heating tube  3 , and the tube support plates  6  arranged at regular vertical intervals to support the heating tube are disposed on the inner side of a wrapper  20  having an open lower portion and an upper portion with a steam outlet  21 . Water is supplied into the lower portion of the wrapper  20 , and is heated into a steam by the heating tube and then is discharged upwards. 
     The steam generator having the above-described structure generates steam as follows: the primary system water flows through the inlet nozzle  1  in the heating tubes  3  so that heat is transferred to the secondary system water fed to the outside of the heating tubes  3 , thereby generating steam. 
     A portion of the steam generator  10  where a reactor coolant flows is referred to as a primary side, and a portion of the steam generator  10  where water is fed and steam flows is referred to as a secondary side. The secondary side of the steam generator includes a main steam system, a turbine system, a condensate water system, and a feed-water system. 
     Thus, steam generated by the secondary side of the steam generator  10  flows through a main steam tube to turn a turbine. 
     The conventional steam generator has a structure in which several thousands of U-shaped heating tubes  3  are disposed in a bundle type such that both ends thereof are fixed to the tube sheet  4  and the heating tubes  3  are supported by the tube support plates  6  that are vertically arranged in seven stages at an interval of about 1 m up to an upper portion of the bundle of heating tubes  3 , as illustrated in  FIGS.  2  and  3   . However, as the number of years of operation passes, impurities introduced or generated through various routes become scale on the outer surface of the heat transfer tubes  3  to degrade a heat exchange function, and are deposited as sludge between the heating tubes  3  and the tube support plates  6  and are gradually solidified, which may cause denting between the support plates  6  and the heating tubes  3  to damage the heating tubes  3 . Accordingly, it is necessary to remove scale stuck to the surface of the heating tubes  3 , sludge deposited on the tube support plates  6 , and foreign substances provided between the heating tubes in order to ensure efficiency of the steam generator and operational reliability of the heating tubes  3 . 
     Existing inspection and removal of foreign substances in the steam generator was performed by checking the presence or absence of foreign substances in a gap between the top of the tube sheet and the bundle of heating tubes  3  and, if there were any foreign substances, removing them. However, there is a problem in that when foreign substances are located on the upper portion of the bundle of heating tubes (tube support plate: top of full egg-crate), it is impossible to check and remove foreign substances with the existing technology. 
     The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present disclosure has been made keeping in mind the above problems occurring in the related art, and an objective of the present disclosure is to provide an apparatus and method of removing foreign substances located on an upper portion of a bundle of heating tubes in a steam generator, which cannot be otherwise removed by conventional removal configurations. 
     According to an aspect of the present disclosure, there is provided an apparatus for removing foreign substances around a heating tube of a steam generator, the apparatus including: a universal machine unit configured to be inserted into, moved along, and discharged out of the heating tube through an opening formed in the heating tube so as to hold the foreign substances; a connecting rod unit including a distal end connecting rod to which the universal machine unit is connected at one end of the distal end connecting rod and which is inserted into and moved along the heating tube so as to move the universal machine unit, and a connecting rod part to which a plurality of connecting rods are connected and which is connected to the distal end connecting rod; a connecting rod moving unit configured to supply the connecting rod unit from the outside to the inside of the heating tube so as to move the connecting rod unit; a connecting rod supply unit provided adjacent to the connecting rod moving unit to sequentially supply the plurality of connecting rods to the connecting rod moving unit; an image-capturing unit configured to be moved to a point where the foreign substances are located through the heating tube to capture an image of the foreign substances to allow a user to check the position of the foreign substances and the approach of the universal machine unit to the foreign substances; and a controller connected to the universal machine unit, the connecting rod moving unit, and the connecting rod supply unit to control operations of the universal machine unit, the connecting rod moving unit, and the connecting rod supply unit. 
     The universal machine unit may include: a first universal machine mounted on the distal end connecting rod positioned at a distal end of the connecting rod unit supplied into the heating tube; and a second universal machine connected to the first universal machine and configured to be moved out of the heating tube through the opening formed in the heating tube so as to hold the foreign substances around the heating pipe. 
     The first universal machine may include: a first mounting body having, at one end thereof, a mounting end mounted on the distal end connecting rod to protrude therefrom; a first servomotor provided in the first mounting body and connected to the controller; a first planetary gear reducer connected to the first servomotor via a rotating shaft; a first worm gear connected to the first planetary gear reducer; and a first rotating finger connected to the first worm gear to rotate up and down by the operation of the first worm gear, and connected to the second universal machine, wherein both ends of the distal end connecting rod are respectively provided with a connecting end, to which the mounting end is connected, and a connector end recess, in a protruding manner, a connector end protrusion is connected to the connector end recess, the connector end protrusion protruding from one end of the connecting rod to which the end connecting rod is connected, and a connector end recess, to which the connector end protrusion is connected, is provided to protrude from the other end of the connecting rod. 
     The second universal machine may include: a second mounting body having a connecting end protruding outward from one end of the second mounting body so as to be connected to the first rotating finger, and a holding end protruding outward from the other end; a second servomotor provided on one end side of the second mounting body and connected to the controller; a second planetary gear reducer connected to the second servomotor via a rotating shaft; a second worm gear connected to the second planetary gear reducer; and a second rotating finger connected to the second worm gear to rotate up and down by the operation of the second worm gear, and operated in association with the holding end to hold the foreign substances. 
     The connecting rod moving unit may include: a first support frame mounted on a tube sheet of the steam generator and having a through-hole through which the connecting rod passes; a second support frame provided to be spaced apart from the first support frame; a plurality of connecting frames connecting the first support frame and the second support frame; a vertical lifting body provided to be moved up and down between the first support frame and the second support frame and having a fastening member to fasten the connecting rod supplied from the connecting rod supply unit; a guide rod provided between the first support frame and the second support frame to be connected to the lifting body so as to guide the movement of the lifting body; and a lifting body moving part mounted on the second support frame to be connected to the lifting body so as to move up and down the lifting body from the guide rod. 
     The second support frame may be provided with a through-hole through which the lifting body moving part passes, the lifting body moving part including: a hydraulic rod connected to the lifting body to move up and down the lifting body during sliding movement thereof; and a hydraulic motor connected to an end of the hydraulic rod to provide power to move the hydraulic rod. 
     The connecting rod supply unit may include: a connecting rod storage rotatably provided in the connecting rod moving unit to store a plurality of connecting rods, and having a plurality of seating recesses spaced apart from each other such that the stored connecting rods are seated therein; a storage-rotary motor connected to the connecting rod storage to provide power to rotate the connecting rod storage in a circumferential direction; 
     a connecting rod supply provided inside the connecting rod storage to rotate and move the connecting rod seated in the plurality of seating recesses to a connecting rod insertion point of the connecting rod moving unit; a supply-rotary motor connected to the connecting rod supply to rotate the connecting rod supply in the circumferential direction of the connecting rod storage; and a mounting frame provided to be spaced apart from the connecting rod storage and connected to the connecting rod moving unit and having a mounting recess provided to mount the connecting rod moved in the connecting rod storage on the connecting rod insertion point, wherein the connecting rod storage has a central hollow cylindrical shape, and the plurality of seating recesses are equidistantly formed to be spaced apart from each other in the circumferential direction of the connecting rod storage. 
     The connecting rod supply may include: a supply-rotary rod provided inside the connecting rod storage to rotate with an external power source to detach the connecting rod seated in the seating recess and supply the same to the mounting recess of the mounting frame; and a rod-rotary unit connected to the supply-rotary rod to rotate the supply-rotary rod while moving up and down the supply-rotary rod in the connecting rod storage. 
     The supply-rotary rod may be circumferentially provided with a plurality of seating protrusions for seating the connecting rod in the seating recess, and when the supply-rotary rod is moved up by the rod-rotary unit, the connecting rod may be seated in the seating recess, and when the supply-rotary rod is moved down, the connecting rod may be detached from the seating recess. 
     The image-capturing unit may include: an endoscope camera configured to move near the foreign substances through the mounting hole and capture an image thereof; a camera control part connected to the endoscope camera to control the operation of the endoscope camera; and a monitor part provided to allow a user to check the image captured by the endoscope camera. 
     According to another aspect of the present disclosure, there is provided a method of removing foreign substances around a heating tube in a steam generator using an apparatus for removing foreign substances from a steam generator, wherein the apparatus includes a universal machine unit, a connecting rod unit including a distal end connecting rod and a plurality of connecting rods, a connecting rod moving unit, an image-capturing unit, and a controller, the method including: a first connecting rod mounting step of inserting the distal end connecting rod, to which the universal machine unit is connected to one end of the distal end connecting rod, into a heating tube, and mounting the connecting rod on the connecting rod moving unit by operating the connecting rod supply unit using the controller; a first connecting rod supply step of supplying the connecting rod mounted on the connecting rod moving unit into the heating tube so as to be connected to the distal end connecting rod by operating the connecting rod moving unit using the controller; a second connecting rod mounting step of mounting the connecting rod on the connecting rod moving unit by operating the connecting rod supply unit using the controller; a second connecting rod supply step of supplying the connecting rod mounted on the connecting rod moving unit into the heating tube so as to be connected to the connecting rod supplied into the heating tube by operating the connecting rod moving unit using the controller; a universal machine unit moving step of supplying a plurality of connecting rods into the heating tube to move the universal machine unit to a point where the foreign substances are located by sequentially performing the first connecting rod mounting step, the first connecting rod supply step, the second connecting rod mounting step, and the second connecting rod supply step; an image-capturing unit moving step of moving the image-capturing unit to the point where the foreign substances are located through the heating tube; and a foreign substance removal step of removing the foreign substances using the universal machine unit while checking the image-capturing unit. 
     According to the apparatus and method of removing foreign substances from a steam generator, the heating tubes can be prevented from being damaged by removing bulky foreign substances such as bolts or the like located on the upper portion of the bundle of heating tubes in the steam generator, which cannot be otherwise removed by conventional methods, thereby preventing quality-related issues that can affect the steam generator and the heating tubes during operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view illustrating a steam generator; 
         FIG.  2    is a front view illustrating the steam generator in  FIG.  1   ; 
         FIG.  3    is a cross-sectional view schematically illustrating an operational principle of the steam generator; 
         FIG.  4    is a front view schematically illustrating a state in which a foreign substance removing apparatus according to an embodiment of the present disclosure is installed in the steam generator, along with an enlarged view of the foreign substance removing apparatus; 
         FIG.  5    is a plan view schematically illustrating a state in which the foreign substance removing apparatus is installed in the steam generator, along with an enlarged view of the foreign substance removing apparatus; 
         FIG.  6    is a view illustrating a state in which a universal machine unit and a connecting rod unit for holding foreign substances in the steam generator to remove the foreign substances are coupled; 
         FIG.  7    is a view illustrating a state in which the universal machine unit illustrated in  FIG.  6    is coupled to the connecting rod unit; 
         FIG.  8    is an enlarged view of a connecting rod supply unit illustrated in  FIG.  4   ; 
         FIG.  9    is an enlarged view of a connecting rod moving unit illustrated in  FIG.  4   ; 
         FIG.  10    is a view illustrating a state in which the connecting rod moving unit in  FIG.  9    lifts and lowers a connecting rod; 
         FIG.  11    is a view illustrating a state in which the universal machine unit holds and removes foreign substances using an imaging means moved to the outside of the heating tubes; and 
         FIG.  12    is a flowchart illustrating a procedure of removing foreign substances from a steam generator using the foreign substance removing apparatus according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Terms or words used in the description and the claims of the present disclosure should not be interpreted as being limited merely to common and dictionary meanings, but should be interpreted as meanings and concepts conforming to the technical spirit of the present disclosure based on the principle that an inventor may properly define the concept of the terms at his/her own discretion in order to describe the invention in the best manner possible. 
     Referring to  FIGS.  4  to  11   , an apparatus  100  for removing foreign substances from a steam generator according to an embodiment of the present disclosure is provided. The apparatus  100  is configured to remove foreign substances from around a heating tube  12  of a steam generator  10 , and includes a universal machine unit  1100 , a connecting rod unit  1200 , a connecting rod moving unit  1300 , a connecting rod supply unit  1400 , an image-capturing unit  1500 , and a controller  1600 . 
     Referring to  FIGS.  6 ,  7 , and  11   , the universal machine unit  1100  is configured to be inserted into the heating tube  12  and moved to the outside of the heating tube  12  through an opening  12   a  formed in the heating tube  12  to hold foreign substances located on top of a bundle of heating tubes  12 . The universal machine unit  1100  is connected to one end of the connecting rod unit  1200  to be described later. 
     According to an embodiment, the universal machine unit  1100  may include a first universal machine  1110  and a second universal machine  1120 . The first universal machine  1110  may be mounted on a distal end connecting rod  1210  positioned on the distal end of the connecting rod unit  1200  to be supplied into the heating tube  12 . The second universal machine  1120  may be connected to the first universal machine  1110  so as to be moved to the outside of the heating tube  12  through the opening  12   a  of the heating tube  12  to hold foreign substances located on top of the bundle of heating tubes  12 . 
     The first universal machine  1110  may include a first mounting body  1111 , a first servomotor  1112 , a first planetary gear reducer  1113 , a first worm gear  1114 , and a first rotation finger  1115 . A mounting end  1111   a  may protrude from one end of the first mounting body  1111  so as to be mounted on the distal end connecting rod  1210  of the connecting rod unit  1200  to be described later. Since the mounting end  1111   a  is mounted on the distal end connecting rod  1210 , one end of the first universal machine  1110  may be connected to the connecting rod unit  1200  to be described later. 
     The first mounting body  1111  may be provided with the first servomotor  1112 , which is connected to the controller  1600  to be described later, and may be operated by the controller  1600  to rotate a rotating shaft (not shown) connected to the first servomotor  1112  in a forward or reverse direction. 
     The rotating shaft (not shown) connected to the first servomotor  1112  configured to be rotated by the controller  1600  may be connected to the first worm gear  1114  through the first planetary gear reducer  1113 . The first planetary gear reducer  1113  may serve to transfer power transferred through the rotating shaft (not shown) to the first worm gear  1114  while decelerating the power. 
     The first planetary gear reducer  1113  may include a sun gear, a planetary gear, and an inner gear. The first planetary gear reducer  1113  may be a generally known planetary gear reducer, and thus a detailed description thereof will be omitted. 
     The first worm gear  1114  may be connected to the first rotation finger  1115 , which is rotated up and down with respect to the first worm gear  1114  by the operation of the first worm gear  1114 . The second universal machine  1120  may be connected to the first rotation finger  1115 . As the first rotation finger  1115  rotates, the second universal machine  1120  connected to the first rotation finger  1115  may also rotate up and down. 
     The second universal machine  1120  may include a second mounting body  1121 , a second servomotor  1122 , a second planetary gear reducer  1123 , a second worm gear  1124 , and a second rotation finger  1125 . A connecting end  1121   a  may be provided on one end of the second mounting body  1121  in a protruding manner. As the connecting end  1121   a  is connected to the first rotation finger  1115 , the first universal machine  1110  and the second universal machine  1120  may be connected. 
     A holding end  1121   b  may be provided on the other end of the second mounting body  1121  so as to protrude outward. The second servomotor  1122  may be provided on the second mounting body  1121 . The second servomotor  1122  may be connected to the controller  1600  to be described later, and operated by the controller  1600  to rotate a rotating shaft (not shown) connected to the second servomotor  1122  in a forward or reverse direction. 
     The rotating shaft (not shown) connected to the second servomotor  1122  configured to be rotated by the controller  1600  may be connected to the second worm gear  1124  through the second planetary gear reducer  1123 . The second planetary gear reducer  1123  may serve to transfer power transferred through the rotating shaft (not shown) to the second worm gear  1124  while decelerating the power. The second worm gear  1124  may have the same configuration as the first worm gear  1114 , and thus a detailed description thereof will be omitted. 
     The second worm gear  1124  may be connected to the second rotation finger  1125 , and the second rotation finger  1125  may be rotated up and down with respect to the second worm gear  1124  by the operation of the second worm gear  1124 . The second rotation finger  1125  may serve to hold foreign substances in association with the holding end  1121   b  protruding outward from the other end of the second mounting body  1121 . 
     Referring to  FIGS.  6  to  8   , one end of the universal machine unit  1100 , particularly, the first mounting body  1111  of the first universal machine  1110 , may be connected to the connecting rod unit  1200 . The connecting rod unit  1200  may be inserted into and moved along the heating tube  12  so as to move the universal machine unit  1100 . 
     According to an embodiment, the connecting rod unit  1200  may include the distal end connecting rod  1210  and a connecting rod part  1220  to which a plurality of connecting rods  1222  are connected. The distal end connecting rod  1210  may be positioned at the distal end of the connecting rod unit  1200  so as to be connected to the universal machine unit  1100 . The connecting rod part  1220  may be connected to the distal end connecting rod  1210 . As the plurality of connecting rods  1222  may be connected to the distal end connecting rod  1210 , the distal end connecting rod  1210  may be lengthened so as to move the universal machine unit  1100  inside the heating tube  12 . The plurality of connecting rods  1222  may be connected in a series or in a sequence and the number of connecting rods to be connected in the series or in the sequence may be controlled by the controller  1600 , thus making the total length of the connecting rod unit  1200  adjustable. 
     A connecting end  1211  may be provided on one end of the distal end connecting rod  1210  in a protruding manner so as to be connected to the mounting end  1111   a  protruding from the first mounting body  1111  of the first universal machine  1110 . As the connecting end  1211  is connected to the mounting end  1111   a,  the distal end connecting rod  1210  and the first universal machine  1110  may be connected so that the connecting rod unit  1200  and the universal machine unit  1100  may be connected. 
     A distal end connecting rod&#39;s connector end recess  1212  may be provided on the other end of the distal end connecting rod  1210  in a protruding manner. As a connector end protrusion  1222   a  provided on the connecting rods  1222  of the connecting rod part  1220  is connected to the distal end connecting rod&#39;s connector end recess  1212 , the distal end connecting rod  1210  and the connecting rod part  1220  are connected. 
     Preferably, the connector end protrusion  1222   a  available to be connected to the distal end connecting rod&#39;s connector end recess  1212  may be provided in a protruding manner on one end of each of the plurality of connecting rods  1222  of the connecting rod part  1220 . In addition, a connector end recess  1222   b  may be provided on the other end of the connecting rods  1222  in a protruding manner. The connector end recess  1222   b  may in a same shape with the distal end connecting rod&#39;s connector end recess  1212 . The connector end protrusion  1222   a  provided on one end of another connecting rod  1222  may be connected to the connector end recess  1222   b  of the another connecting rod  1222 . As the plurality of connecting rods  1222  are connected or disconnected by the connector end protrusion  1222   a  and the connector end recess  1222   b,  the length of the connecting rod part  1220  may be increased or reduced. 
     Referring to  FIGS.  8  to  10   , as the connecting rod unit  1200  is supplied into the heating tube  12  from the outside the heating tube  12  by the connecting rod moving unit  1300 . According to an embodiment, the length of the connecting rod unit  1200  may be increased and one end of the connecting rod unit  1200  may be moved inside the heating tube  12 , thereby moving the universal machine unit  1100  connected to one end of the connecting rod unit  1200 . 
     According to an embodiment, the connecting rod moving unit  1300  may be positioned outside the heating tube  12 , and may include a first support frame  1310 , a second support frame  1320 , a plurality of connecting frames  1330 , a vertical lifting body  1340 , a guide rod  1350 , and a vertical lifting body moving part  1360 . 
     The first support frame  1310  may be mounted on a tube sheet  10   a  of the steam generator  10 , and provided with a through-hole through which the connecting rod unit  1200  passes. Preferably, the first support frame  1310  may be mounted on the tube sheet  10   a  using a mounting unit (not shown). 
     The second support frame  1320  may be spaced apart from the first support frame  1310 . The first support frame  1310  and the second support frame  1320  spaced apart from each other may be connected by the plurality of connecting frames  1330 . Particularly, both ends of each of the plurality of connecting frames  1330  may be mounted on the support frame  1310  and the second support frame  1320  by a mounting unit (not shown). 
     The vertical lifting body  1340  may be provided between the first support frame  1310  and the second support frame  1320 . The vertical lifting body  1340  may be provided with a fastening member (not shown) for fastening the connecting rods  1222  supplied from the connecting rod supply unit  1400  to be described later. The vertical lifting body  1340  may supply the connecting rods  1222  into the heating tube  12  while moving up and down between the first support frame  1310  and the second support frame  1320 . 
     The guide rod  1350  may be provided between the first support frame  1310  and the second support frame  1320 . The vertical lifting body  1340  may be connected to the guide rod  1350 . The guide rod  1350  serves to guide up-down movement of the vertical lifting body  1340 . 
     The vertical lifting body moving part  1360  may be mounted on the second support frame  1320 . The vertical lifting body moving part  1360  may be positioned vertically downside of the second support frame  1320 . The vertical lifting body moving part  1360  may be connected to the vertical lifting body  1340  to vertically move the vertical lifting body  1340  on the guide rod  1350 . The vertical lifting body moving part  1360  may include a hydraulic rod  1361  and a hydraulic motor  1362 . 
     Particularly, the second support frame  1320 , on which the vertical lifting body moving part  1360  is mounted, may be provided with a through-hole (not shown) through which the vertical lifting body moving part  1360  passes. One end of the hydraulic rod  1361  may be connected to the vertical lifting body  1340  to vertically move the vertical lifting body  1340  during sliding movement. The other end of the hydraulic rod  1361  may be connected to the hydraulic motor  1362 . The hydraulic motor  1362  may serve to provide power to vertically move the hydraulic rod  1361 . The components of the vertical lifting body moving part  1360  are not limited to the hydraulic rod  1361  and the hydraulic motor  1362 . Other means for performing the same function to vertically move the vertical lifting body  1340  may be used. 
     Referring to  FIGS.  4 ,  5 , and  8   , according to an embodiment, the connecting rod supply unit  1400  may be provided adjacent to the connecting rod moving unit  1300 . The connecting rod supply unit  1400  may serve to sequentially supply the plurality of connecting rods  1222  to the connecting rod moving unit  1300 . The connecting rod supply unit  1400  may include a connecting rod storage  1410 , a storage-rotary motor  1420 , a connecting rod supply  1430 , and a supply-rotary motor  1440 . The connecting rod supply unit  1400  may further include a mounting frame  1450 . 
     The connecting rod storage  1410  may be rotatably provided adjacent to the connecting rod moving unit  1300 . The connecting rod storage  1410  may have a central hollow cylindrical portion. The connecting rod storage  1410  may be provided with a plurality of seating recesses  1412  in which the plurality of connecting rods  1222  are stored. The plurality of seating recesses  1412  may be equidistantly spaced apart from each other in a circumferential direction of the connecting rod storage  1410 . The connecting rod storage  1410  may be connected to the storage-rotary motor  1420  to rotate about the central portion of the connecting rod storage  1410 . The storage-rotary motor  1420  may serve to provide power to rotate the connecting rod storage  1410 . 
     The connecting rod supply  1430  may be provided inside the connecting rod storage  1410 . The connecting rod supply  1430  may serve to move the connecting rods  1222  seated in the plurality of seating recesses  1412  to a connecting rod insertion point (not shown) of the connecting rod moving unit  1300  while rotating inside the connecting rod storage  1410 . The connecting rod supply  1430  rotated by the supply-rotary motor  1440  may include a supply-rotary rod  1431  and a rod-rotary unit  1432 . 
     The connecting rod supply  1430  may be connected to the supply-rotary motor  1440 . The supply-rotary motor  1440  may serve to provide power to rotate the connecting rod supply  1430  in the circumferential direction of the connecting rod supply  1430 . 
     The mounting frame  1450  may be provided to be spaced apart from the connecting rod storage  1410 . The mounting frame  1450  may be connected to the connecting rod moving unit  1300 . Particularly, the mounting frame  1450  may be provided with a mounting recess  1452  in which the connecting rods  1222  to be moved in the connecting rod storage  1410  is mounted on the connecting rod insertion point (not shown). 
     The supply-rotary rod  1431  may be provided inside the connecting rod storage  1410  so as to be rotated by an external power source to seat the connecting rods  1222  in the seating recesses  1412  or detach the connecting rods  1222  seated in the seating recesses  1412  and supply the connecting rods to the mounting recess  1452  of the mounting frame  1450 . The supply-rotary rod  1431  may be provided with a plurality of seating protrusions  1431   a.    
     The rod-rotary unit  1432  may be connected to the supply-rotary rod  1431  to rotate the supply-rotary rod  1431  while vertically moving the same in the connecting rod storage  1410 . When the supply-rotary rod  1431  moves upward in the connecting rod storage  1410  by the rod-rotary unit  1432 , the connecting rods  1222  may be seated in the seating recesses  1412 , and when the supply-rotary rod  1431  moves downward in the connecting rod storage  1410  by the rod-rotary unit  1432 , the connecting rods  1222  may be detached from the seating recesses  1412  and supplied to the mounting recess  1452  of the mounting frame  1450 . 
     The plurality of seating protrusions  1431   a  may serve to prevent the connecting rods  1222  seated in the plurality of seating recesses  1412  of the connecting rod storage  1410  from being detached from the seating recesses  1412 . Mounting protrusions  1431   b  may serve to detach the connecting rods  1222 , seated in the seating recesses  1412 , from the seating recesses  1412 . The connecting rods  1222  detached from the seating recesses  1412  may be supplied to the mounting recess  1452  of the mounting frame  1450 . Particularly, the mounting protrusions  1431   b  are positioned below the plurality of seating protrusions  1431   a  formed on the circumferential surface of the supply-rotary rod  1431 . Referring to  FIG.  11   , according to an embodiment, the image-capturing unit  1500  may move to a position where foreign substances are positioned through the heating tube  12 . The image-capturing unit  1500  may move inside the heating tube  12  and then exits the heating tube  12  to a position through the opening  12   a  of the heating tube  12 . At that position, the image-capturing unit  1500  may serve to capture an image of the foreign substances and transmits the captured image so that an operator may determine the position of the foreign substances and the approach of the universal machine unit  1100  to the foreign substances. 
     The image-capturing unit  1500  may include an endoscope camera  1510 , a camera control part  1520 , and a monitor part (not shown). The endoscope camera  1510  may be inserted into and moves inside the heating tube  12 . The camera control part  1520 , which is held by a user to operate the endoscope camera  1510 , may be connected to the other end of the endoscope camera  1510 . Since the endoscope camera  1510  moves inside the heating tube  12  to a position where foreign substances are present through the opening  12   a  of the heating tube  12 , the endoscope camera  1510  may smoothly move without disturbance by the bundle of heating tubes  12 . 
     The image captured by the endoscope camera  1510  may be transmitted to the monitor part (not shown). Then, the user may hold the foreign substances positioned on top of the bundle of heating tube and then remove the same using the universal machine unit  1100  while watching the monitor part (not shown). The endoscope camera  1510  and a method of operating the endoscope camera  1510  are well-known in the art, so a detailed description thereof will be omitted. 
     Referring to  FIGS.  4  and  5   , according to an embodiment, the universal machine unit  1100 , the connecting rod moving unit  1300 , and the connecting rod supply unit  1400  may be connected to the controller  1600 . The controller  1600  may serve to control the operation of the universal machine unit  1100 , the connecting rod moving unit  1300 , and the connecting rod supply unit  1400 . The operation of the controller  1600  may be preferably controlled by a user. 
     The image-capturing unit  1500  and the universal machine unit  1100  may smoothly move to the foreign substances positioned on top of the bundle of heating tubes  12  through the opening  12   a  of the heating tube  12  without disturbance by the bundle of heating tubes  12 . Thus, the bulky foreign substances, such as bolts or the like, located on top of the bundle of heating tubes  12  may be held and retrieved using the universal machine unit  1100  that is easy to operate, thereby preventing the heating tubes  12  from being damaged. 
     Referring to  FIGS.  4  to  12   , according to an embodiment of the present disclosure, there is provided a method of removing foreign substances, such as bolts or the like, located on top of a bundle of heating tubes in a steam generator using the foreign substance removing apparatus  100  according to the embodiment of the present disclosure. The apparatus  100  includes a universal machine unit  1100 , a connecting rod unit  1200 , a connecting rod moving unit  1300 , a connecting rod supply unit  1400 , an image-capturing unit  1500 , and a controller  1600 . The method includes a first connecting rod mounting step S 10 , a first connecting rod supply step S 20 , a second connecting rod mounting step S 30 , a second connecting rod supply step S 40 , a universal machine unit moving step S 50 , an image-capturing unit moving step S 60 , and a foreign substance removal step S 70 . 
     Referring to  FIGS.  8 ,  10  and  12   , according to an embodiment, in the first connecting rod mounting step S 10 , after the end connecting rod  1210  of the connecting rod unit  1200 , to which the universal machine unit  1100  is connected at one end, may be inserted into the heating tube  12 , the plurality of connecting rods  1222  constituting the connecting rod part  1220  of the connecting rod unit  1200  may be mounted on the connecting rod moving unit  1300  by the connecting rod supply unit  1400  operated by the controller  1600 . One of the plurality of connecting rods  1222  seated in the connecting rod storage  1410  of the connecting rod supply unit  1400  may be mounted on the lifting body  1340  of the connecting rod moving unit  1300  by operating the connecting rod supply unit  1400  using the controller  1600 . 
     After the first connecting rod mounting step S 10 , the first connecting rod supply step S 20  may be performed such that the connecting rod  1222  mounted on the lifting body  1340  of the connecting rod moving unit  1300  is supplied into the heating tube so as to be connected to the distal end connecting rod  1210  inserted into the heating tube  12  by the connecting rod moving unit  1300  operated by the controller  1600 . The lifting body  1340 , on which the connecting rod  1222  is mounted, may be moved up by the lifting body moving part  1360  so that the connecting rod  1222  is moved into the heating tube  12  and connected to the distal end connecting rod  1210  to allow the universal machine unit  1100  connected to the distal end connecting rod  1210  to be moved inside the heating tube  12 . 
     After the first connecting rod supply step S 20 , the second connecting rod mounting step S 30  may be performed. It is preferred that before the second connecting rod mounting step S 30 , the lifting body moving the connecting rod  12  may return to its original state in the first connecting rod supply step S 20 . 
     The second connecting rod mounting step S 30  may be a step of mounting the connecting rods  1222  on the connecting rod moving unit  1300  by operating the connecting rod supply unit  1400  using the controller  1600 . Another connecting rod  1222  seated in the connecting rod storage  1410  of the connecting rod supply unit  1400  may be mounted on the vertical lifting body  1340  of the connecting rod moving unit  1300  by operating the connecting rod supply unit  1400  using the controller  1600 . 
     After the second connecting rod mounting step S 30 , the second connecting rod supply step S 40  may be performed. The second connecting rod supply step S 40  is a step of inputting another connecting rod  1222  mounted on the vertical lifting body  1340  of the connecting rod moving unit  1300  into heating tube  12  by operating the connecting rod moving unit  1300  using controller  1600 , so that the other connecting rod  1222  may be connected to the connecting rod  1222  connected to the distal end connecting rod  1210  on which the universal machine unit  1100  is mounted. 
     As the vertical lifting body moving part  1360  vertically lifts the vertical lifting body  1340  on which the connecting rods  1222  are mounted, the other connecting rod  1222  may be moved into the heating tube  12  and connected to the connecting rod  1222  connected to the distal end connecting rod  1210 , thereby increasing the length of the connecting rod unit  1200  connected to the universal machine unit  1100 . 
     After the second connecting rod supply step S 40 , the universal machine unit moving step S 50  may be performed. The universal machine unit moving step S 50  is a step of supplying the plurality of connecting rods  1222  into the heating tube  12  by sequentially repeating the first connecting rod mounting step S 10 , the first connecting rod supply step S 20 , the second connecting rod mounting step S 30 , and the second connecting rod supply step S 40 , thereby moving the universal machine unit  1100  to a point at which foreign substances are located through the heating tube  12 . 
     Referring to  FIGS.  6  and  7   , according to an embodiment, the plurality of connecting rods  1222  may be sequentially supplied into the heating tube  12  and connected to each other, thereby increasing the length of the connecting rod unit  1200 . The universal machine unit  1100  mounted on the connecting rod unit  1200  may be moved inside the heating tube  12  by the increased length and moved to the point at which foreign substrates are located through the opening  12   a  of the heating tube  12 . 
     Since detailed descriptions of the connecting rod supply unit  1400  supplying the connecting rods  1222  and the connecting rod moving unit  1300  moving the connecting rods  1222  into the heating tube  12  have been provided in the description of the apparatus  100  for removing foreign substances from a steam generator according to an embodiment of the present disclosure, repetitive descriptions thereof will be omitted. 
     Referring to  FIG.  12   , after the universal machine unit moving step S 50 , the image-capturing unit moving step S 60  is performed. The image-capturing unit moving step S 60  is a step of moving the image-capturing unit  1500  through a heating tube  12  adjacent to the heating tube  12  through which the universal machine unit  1100  is moving. 
     Referring to  FIG.  11   , the image-capturing unit  1500  may include the endoscope camera  1510 , the camera control part  1520 , and the monitor part (not shown). The image-capturing unit  1500  may be moved through the heating tube  12  adjacent to the heating tube  12  through which the universal machine unit  1100  is moved. In this manner, the image-capturing unit  1500  may serve to determine the position of foreign substances, capture images of the universal machine unit  1100 , and transmit the captured images, thereby allowing the user to recognize the universal machine unit  1100  approaching foreign substances to hold and remove foreign substances. 
     Referring to  FIGS.  6  and  12   , after the image-capturing unit moving step S 60 , the foreign substance removal step S 70  is performed. The foreign substance removal step S 70  is a step of removing foreign substances using the universal machine unit  1100  while recognizing the image-capturing unit  1500 . 
     In the foreign substance removal step S 70 , the universal machine unit  1100 , which holds and removes foreign substances, may include the first universal machine  1110  and the second universal machine  1120 . Since a detailed description of the universal machine unit  1100  has been provided in the description of the apparatus  100  for removing foreign substances from a steam generator according to an embodiment of the present disclosure, a repetitive description thereof will be omitted. 
     It is preferable to perform a removing apparatus recovery step (not shown) of recovering the connecting rod unit  1200  and the universal machine unit  1100  after performing the foreign substance removal step S 70 . 
     According to the apparatus and method of removing foreign substances from a steam generator, the heating tubes  12  can be protected from being damaged by removing bulky foreign substances such as bolts or the like located on the upper portion of the bundle of heating tubes  12  in the steam generator  10 , which cannot be otherwise removed by conventional methods. Thereby, the present disclosure prevents quality-related issues that can affect the steam generator  10  and the heating tubes  12  during operation. 
     Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, the described embodiments are merely illustrative, so those skilled in the art will understand that various modifications and equivalents thereof can be made therefrom. Therefore, the true technical scope of the present disclosure should be determined by the technical spirit of the appended claims.