Abstract:
A working apparatus has: a working equipment for doing works on a structure; a folding/unfolding mechanism for conveying the working equipment to the working position in a folded state; a conveyance mechanism (such as a horizontal thruster) for conveying the working equipment and the folding/unfolding mechanism to the working position; a pressing mechanism (such as a ballast tank) for pressing the working equipment against the lower surface of the structure; and a traveling mechanism including a wheel for traveling along the lower surface of the structure and positioning the apparatus.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   The present invention contains subject matter related to Japanese Patent Application No. 2005-115937, filed in the Japanese Patent Office on Apr. 13, 2005 and Japanese Patent Application No. 2005-172315 filed in the Japanese Patent Office on Jun. 13, 2005, the entire contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   This invention relates to a working apparatus for doing works in a lower part of the inside of a nuclear reactor or the like and a working method of operating such an apparatus. 
   Intra-nuclear-reactor working apparatus are generally used for intra-reactor operations such as inspections, examinations and preventive maintenances of the inner surface of nuclear reactor pressure vessels (RPVs) and intra-reactor structures. Particularly, when the weld line found in a lower part of the shroud support plate of a lower part of a boiling water nuclear reactor is the target of operation, it is difficult for the intra-nuclear-reactor working apparatus to get to the weld line and the operation faces various problems such as a limited working space and a long working time because it is difficult to access the target that is located in a very narrow area. Various intra-nuclear-reactor working apparatus have been proposed to carry out such an operation in a short period of time and secure a larger working space at a place having access difficulties. 
   Firstly, an intra-nuclear-reactor working apparatus comprising a remotely operated vehicle (ROV) to be used in water that is equipped with a thruster for moving back and forth and for turning, a thruster for moving up and down and for moving sideways and an underwater camera is known (See, inter alia, Japanese Patent Application Laid-Open Publication No. Hei 11-14784, the entire contents of which being incorporated herein by reference). The apparatus disclosed in the cited reference is provided with an arm mechanism that can be turned and an inspection means selected from an ultrasonic inspection means, a radiation-resistance television camera, an infrared camera and so on is replaceably fitted to the front end of the mechanism. 
   In this known apparatus, an X-Y scanner mechanism is arranged at the front end of the arm mechanism and any of a various inspection means is fitted to the scanner mechanism. For example, the arm mechanism and the selected inspection means are conveyed to the site of inspection by means of the thrusters of the underwater ROV and the X-Y scanner is pressed near the target of inspection and operated to scan the target by the selected inspection means, utilizing the degree of freedom of operation of the X-Y scanner. 
   Secondly, a vehicle type mobile body designed to be used as intra-nuclear-reactor working apparatus as described below is known (See Japanese Patent Application Laid-Open Publication No. 2001-296385, the entire contents of which being incorporated herein by reference). This apparatus has a plurality of wheeled arms (cylinder rods) to be extended under the shroud support plate toward the RPV and the shroud support to make the apparatus itself to be preliminarily anchored there. Then, thrusters or the wheels that the mobile body is provided with are driven to move the apparatus to the working site along the periphery. The pressure being applied to the cylinder rods is raised there in order to securely anchor the apparatus. 
   The apparatus is held in position by the wheels that are pressed by unfolding the work reaction force exerted by the object of work, in other words, the apparatus can hold a large work reaction force. Additionally, it is possible to accurately position the apparatus in a peripheral direction so that the apparatus can be highly reliable in repeated positioning by driving the wheels to travel and move. 
   VT (visual testing) apparatus realized by mounting an inspection camera on a swimming type vehicle and UT (ultrasonic testing) apparatus realized by combining a swimming type vehicle and an arm to mount a UT probe for the purpose of inspecting weld lines in water located under the shroud support plate in a lower part of the core are known. 
   It is possible to inspect a broad area in a short period of time in order to efficiently perform an assigned work by using such a swimming type vehicle and auxiliary mechanisms such as arms, because of their mobility and flexibility. 
   However, preventive maintenance works and welding works involving brush polishing, water washing, water jet peening and/or laser peening encounter a large reaction force in the work, and hence it is difficult to carry out the work by using a swimming type vehicle for conveying objects, positioning itself and holding the position. Additionally, it is difficult for such a swimming type vehicle to move accurately and position itself to give rise to a difficulty in repeated positioning. 
   On the other hand, a system for unfolding traveling wheels toward the inner wall of a pressure vessel and a shroud support, anchoring itself to a given position and driving thrusters or wheels to move horizontally, can utilize a large reaction force in the work to support itself and move and position itself accurately. 
   However, when such a system is driven to travel by means of wheels in a peripheral direction of the shroud or the RPV, it can be vertically displaced. It is difficult to prevent or suppress such a vertical displacement. 
   In view of the above-identified problems of the prior art, it is therefore an object of the present invention to provide a working apparatus and a working method that are adapted to move over a broad range within a short period of time with a limited number of setting operations, withstand a large reaction force and easily position itself repeatedly, moving along a structure in water and positioning itself. 
   BRIEF SUMMARY OF THE INVENTION 
   In order to attain the object, according to an aspect of the present invention, a working apparatus for doing works below a structure is provided. The apparatus comprises: a working equipment for doing works; a folding/unfolding mechanism that can be folded when moving the working equipment and unfolded when doing a work; a conveyance mechanism for conveying the working equipment and the folding/unfolding mechanism to the site of the work; a pressing mechanism for pressing the working equipment against the structure; and a traveling mechanism including wheels for traveling under and along the structure and positioning the apparatus. 
   According to another aspect of the present invention, a working apparatus for doing works on a structure in water is provided. The apparatus comprises: a main body casing including a ballast tank; a working equipment arranged at an upper part of the main body casing so as to be able to project outward by way of a drive mechanism and adapted to do various works on the structure; a float arranged at an upper part of the main body casing so as to be able to project outward by way of a drive mechanism; and wheels arranged at outside of the working equipment and the float and adapted to abut the structure so as to turn the working equipment and the float. 
   According to another aspect of the present invention, a working method for doing works under a structure is provided. The method comprises: conveying a working equipment and a folding/unfolding mechanism to a working position with the folding/unfolding mechanism held in a folded state; unfolding the folding/unfolding mechanism and setting up the working equipment under the structure after conveying the working equipment and the folding/unfolding mechanism to the working position; pressing the set up working equipment against a lower surface of the structure; moving the working equipment along the lower surface of the structure and positioning it; and doing a work on the structure by means of the moved and positioned working equipment. 
   According to another aspect of the present invention, a working method for doing works under a shroud support plate arranged between a nuclear reactor pressure vessel and a shroud is provided. The method comprises: removing an access hole cover fitted to an access hole arranged at the shroud support plate; conveying a working equipment under the shroud support plate through the access hole after the cover removing step; and doing a work at a lower part in the nuclear reactor by means of the conveyed working equipment after the conveying step. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view of a first embodiment of intra-nuclear-reactor working apparatus according to the present invention, showing how it is arranged in position; 
       FIG. 2  is a front view of the intra-nuclear-reactor working apparatus of  FIG. 1 , showing the configuration thereof; 
       FIG. 3  is a plan view of the intra-nuclear-reactor working apparatus of  FIG. 1 , showing the configuration thereof; 
       FIG. 4  is a front view of the wheel folding/unfolding mechanism of  FIG. 1 , showing the configuration thereof; 
       FIG. 5  is a front view of the first embodiment of intra-nuclear-reactor working apparatus according to the present invention, showing how it is operated; 
       FIG. 6  is a plan view of the first embodiment of intra-nuclear-reactor working apparatus according to the present invention, showing how it is operated; 
       FIG. 7  is a front view of a second embodiment of intra-nuclear-reactor working apparatus, showing the configuration thereof; 
       FIG. 8  is a schematic cross sectional view of a third embodiment of the present invention, conceptually showing access routes for accessing a lower part of the shroud support plate in a nuclear reactor; 
       FIG. 9  is a schematic cross sectional plan view of the third embodiment of the present invention, conceptually showing the access hole covers and the positions of the access hole covers; 
       FIG. 10  is a plan view of the access hole cover of the third embodiment of the present invention; and 
       FIG. 11  is an elevational view of a bolt for anchoring the access hole cover of the third embodiment and its vicinity. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Now, embodiments of the working apparatus and working method according to the present invention will be described referring to the accompanying drawings. Throughout the drawings, the same or similar components are denoted respectively by the same reference symbols and will not be described repeatedly. 
   First Embodiment 
     FIG. 1  is a schematic cross sectional view of the first embodiment of intra-nuclear-reactor working apparatus according to the present invention, showing how it is arranged in position. 
   Referring to  FIG. 1  that illustrates a lower part of a nuclear reactor that is the working site in the nuclear reactor, the site is found in a narrow area located below the shroud support plate  7  and surrounded by the inner wall of the nuclear reactor pressure vessel (RPV)  2 , the shroud support cylinder  5  on which a nuclear fuel assemblies are placed, the shroud support legs  6  that are legs of the shroud support cylinder  5 , and so on. The shroud support plate  7  is a horizontal annular plate arranged between the shroud support cylinder  5  and the RPV  2 . 
   A large number of weld lines are found in such a narrow area. They include an H8 horizontal weld line  9  that is the weld line connecting the shroud support cylinder  5  and the shroud support plate  7 , and an H9 horizontal weld line  10  that is the weld line connecting the RPV  2  and the shroud support plate  7 , along with an H10 weld line  11 , an H11 weld line  12  and an AD-2 weld line  13 . 
   When conducting various works for these weld lines  9  to  13 , such as inspection, polishing, water washing, preventive maintenance and repairing, the inside of the RPV  2  is filled with water and the intra-nuclear-reactor working apparatus  20  is arranged in the water. A cable (not shown) is connected to the intra-nuclear-reactor working apparatus  20  and the other end of the cable is connected to the control section and the operation section of the control apparatus arranged on the operating floor or on the fuel exchanger located above the RPV  2 . 
   Now, the intra-nuclear-reactor working apparatus  20  will be described below.  FIG. 2  is a front view of the intra-nuclear-reactor working apparatus  20  of  FIG. 1 , showing the configuration thereof.  FIG. 3  is a schematic plan view of the intra-nuclear-reactor working apparatus  20  of  FIG. 1 , showing the configuration thereof.  FIG. 4  is a front view of the wheel folding/unfolding mechanism  32  of  FIG. 1 , showing the configuration thereof. 
   As shown in the drawings, the intra-nuclear-reactor working apparatus  20  includes a cylindrical main body casing  22  that contains a ballast tank  21 . Wheel folding/unfolding mechanisms  23 ,  32  for unfolding a working equipment  30  or a traveling wheel  24  are mounted in an upper part of the main body casing  22 . 
   At least three folded traveling wheels  24  to be unfolded are provided. The working equipment  30  is arranged between a pair of traveling wheels  24 . Ball casters  25  are fitted respectively to upper parts of the three traveling wheels  24 . An original point detection sensor  31  for defining an original point is fitted to an upper part of the intra-nuclear-reactor working apparatus  20 . Two vertical thrusters  28  are fitted to a lower part of the main body casing  22  (although only one of them is shown in  FIG. 4 ) so as to be driven by a drive motor  27 . Further, two vertical thrusters  26  are fitted to a center part of the main body casing  22  (although only one of them is shown in  FIG. 4 ) so as to driven by a drive motor (not shown). 
   The main body casing  22  has a cylindrical profile and is dimensionally so designed as to be able to pass through a round hole (not shown) of the reactor core support plate  3 . The total height of the intra-nuclear-reactor working apparatus  20  is dimensionally so defined that, after passing through the round hole of the reactor core support plate  3  and moving into a lower part of the reactor, the apparatus  20  can pass among the shroud support legs  6  and move into an area below the shroud support plate  7 . 
   A plurality of floats  29   a ,  29   b  are arranged at an upper part of the intra-nuclear-reactor working apparatus  20  so as to position the center of buoyancy above the center of gravity in water even after injecting air into the ballast tank  21  to completely fill the latter with air so that the intra-nuclear-reactor working apparatus  20  can hold its attitude without toppling down in water. 
   As shown in  FIG. 3 , at least three wheel folding/unfolding mechanisms  23 ,  32  are arranged in the intra-nuclear-reactor working apparatus  20 . Referring to the drawings, two floats  29   a , a wheel  24  and a ball caster  25  are fitted to a single wheel folding/unfolding mechanism  23 , whereas a float  29   b  is sandwiched between a pair of wheel folding/unfolding mechanisms  32 , and a wheel  24  and a ball caster  25  are fitted to the front end of each of the wheel folding/unfolding mechanisms  32 . The traveling wheels  24  of the wheel folding/unfolding mechanisms  23 ,  32  are driven by respective wheel drive motors  40  that are directly and coaxially linked to the rotary shafts thereof. 
   A roller  46  for gauging the distance by which the roller traveled along the outer lateral surface of the shroud and a rotary sensor  45  directly linked to it are fitted to the lower end of each of the wheel drive motors  40 . The traveling wheels  24 , the rollers  46  and the rotary sensors  45  are linked to the main body casing  22  by way of parallel links  42  in such a way that each of the wheel folding/unfolding mechanisms can be stored in position with the wheel rotary shaft held upright by means of an air cylinder  41 . Each of the parallel links  42  is supported at the opposite ends thereof by brackets  60  and pins  61  so as to be able to rotate freely. 
   The intra-nuclear-reactor working apparatus  20  moves down below the shroud support plate  7  as the wheel folding/unfolding mechanisms  23 ,  32  are held upright and stored in position. Thereafter, the traveling wheels  24 , the rollers  46  and the rotary sensors  45  are pressed against the shroud support cylinder  5  and the inner wall of the RPV  2  by supplying air to the air cylinders  41  to generate traveling drive force in a horizontal direction so that the intra-nuclear-reactor working apparatus  20  can move along the outer peripheral surface of the shroud. At the same time, it is possible to gauge the relative distance by which the intra-nuclear-reactor working apparatus  20  traveled along the outer peripheral surface of the shroud by means of the rollers  46  and the rotary sensors  45  pressed against the outer peripheral surface. 
   While the driving air cylinders  41  are arranged at an upper part of the main body casing  22  in the illustrated embodiment, drive sources may alternatively be arranged below the ballast tanks  21  for the wheel folding/unfolding mechanisms  23 ,  32  to produce links that can be unfolded by the drive sources. With such an arrangement, the attitude of the intra-nuclear-reactor working apparatus  20  can be made more stable in water because the center of gravity is lowered by the arrangement. 
   Now, how the intra-nuclear-reactor working apparatus  20  is handled will be described below.  FIG. 5  is a front view of the intra-nuclear-reactor working apparatus  20  of the first embodiment according to the present invention, showing how it is operated, and  FIG. 6  is a plan view of the intra-nuclear-reactor working apparatus of this embodiment, also showing how it is operated. 
   The intra-nuclear-reactor working apparatus  20  is adapted to carry out various operations, for instance, on the H 8  horizontal weld line  9  that is the weld line located under the shroud support plate  7  as shown in  FIG. 1 . 
   The intra-nuclear-reactor working apparatus  20  is suspended from above the RPV  2  by means of a cable (not shown) and lowered into the RPV  2  that is filled with water. Then, it is moved into a narrow area located in a lower part of the reactor, passing by an upper grid plate and the reactor core support plate  3 . At this time, the insides of the ballast tanks  21  are evacuated and water is injected into them to reduce the buoyancy and generate a falling force. At the same time, downwardly propelling force of the vertical thrusters  28  are combined with the falling force to drive the intra-nuclear-reactor working apparatus  20  downwardly in water. Then, the intra-nuclear-reactor working apparatus  20  is made to pass among the shroud support legs  6  and go below the shroud support plate  7 . 
   When driving the intra-nuclear-reactor working apparatus  20  to move, air is injected into the ballast tank  21  or water is discharged from the inside of the ballast tank  21  to make the weight of the entire apparatus substantially equal to 0 kgf in water and drive the apparatus horizontally by means of the horizontal thrusters  26 . Then, the working equipment  30  made to face the shroud support cylinder  5  by rotating it around the vertical axis. 
   Thereafter, the traveling wheels  24  are unfolded until immediately before they touch the outer peripheral surface of the shroud support cylinder  5 . Then, air is injected into the ballast tank  21  to expel the water in the inside and lift up the intra-nuclear-reactor working apparatus  20  until the three ball casters  25  touch the lower surface of the shroud support plate  7 . 
   As the vertical position of the intra-nuclear-reactor working apparatus  20  is determined in the above-described manner, the unfolding power is raised to press the traveling wheels  24  firmly against the shroud support cylinder  5  and the inner wall of the RPV  2 . For traveling, the traveling wheels  24  are driven to turn, while the ball casters  25  are constantly held in contact with the lower surface of the shroud support plate  7  by the buoyancy generated by the ballast tank  21 . Then, as a result, it is possible to move the intra-nuclear-reactor working apparatus  20  horizontally along the H8 weld line  9 . 
   The reference position in a peripheral direction for the H8 horizontal weld line  9 , or the original point for traveling, is defined by detecting the inner edge of the round hole of the shroud support plate  7  where the jet pump adaptor  8  is rigidly anchored by means of an original detecting sensor  31 , which may typically be an ultrasonic distance sensor. 
   Then, the rollers  46  are made to contact the wall surface to directly gauge the traveled distance by the rotary sensors  45  and computationally determine the traveled relative distance from the original point by the rotary sensors  45 . Then, the intended work is carried out by means of an appropriate one of the various pieces of working equipment  30 , while remotely regulating the relative position and the attitude of the apparatus relative to the target of work by means of the scanning mechanism. If the work is a visual inspection, a CCD camera is mounted as working equipment  30  and a universal head is mounted as scanning mechanism. Then, the weld line and its vicinity will be continuously shot, while moving the apparatus horizontally and regulating the universal head and the camera angle so as to shoot the desired region. 
   Alternatively, an ultrasonic flaw detection sensor or an eddy current flaw detection sensor may be mounted with a scanning mechanism having a desired degree of freedom to carry out a similar work. 
   Any of various works can also be performed for the H9 horizontal weld line  10  by moving so as to make the working equipment  30  face the inner wall of the RPV  2  and unfolding the related components, following a similar sequence of operation. 
   With this embodiment, it is possible to perform a preventive maintenance operation or a welding operation such as an inspection, a cleaning operation, a polishing operation, water washing, water jet peening and/or a laser peening operation to a weld line that is found in a hard-to-be-accessed area below the shroud support plate  7  when conducting any of various operations on the intra-reactor structures in the nuclear reactor pressure vessel that is immersed in water in a nuclear reactor. 
   Additionally, the working apparatus can cover a wide area with a limited number of times of immersions of installations to carry out works efficiently. 
   Still additionally, since the traveling wheels  24  are unfolded and pressed against a wall, it is possible to support a large reaction force and hence carry out a work stably. 
   Furthermore, since the intra-nuclear-reactor working apparatus can continuously travel on the outer wall surface of the shroud support cylinder  5  by means of the traveling wheels  24 , it is possible to accurately and continuously position the apparatus and restore the apparatus to an original position. Thus, it is possible to improve the quality of the work it carries out. Sine the intra-nuclear-reactor working apparatus can move along the lower surface of the shroud support plate  7  by utilizing buoyancy, the vertical position of the apparatus can be reliably secured to further improve the quality of the work it carries out. 
   The working equipment  30  is selected from a brush for polishing operations, a grinding jig, a washing water nozzle, a water jet peening head for preventive maintenance, a laser peening head and a welding head for repairing works and mounted in the intra-nuclear-reactor working apparatus. 
   Thus, by using any of these pieces of working equipment  30 , it is possible to perform polishing operations, cleaning operations, operation for improving stresses as preventive maintenance and repairing operations. 
   Therefore, with this embodiment, it is possible to perform, in addition to inspection, polishing operations, cleaning operations, operation for improving stresses as preventive maintenance and repairing operations on the weld lines located in a narrow area under the shroud support plate which is difficult to access. 
   In this embodiment, the conveyance mechanism of the intra-nuclear-reactor working apparatus is realized by the two horizontal thrusters  26  and by regulating the buoyancy of the ballast tank  21 . 
   More specifically, the embodiment is driven to move up and down respectively by the rising power and the falling power generated by the ballast tank  21 . It is driven to move horizontally and turn around a vertical axis by the propelling force of the horizontal thrusters. 
   This embodiment provides improved handling capabilities because the degree of freedom of driving and the number of cables are reduced. Additionally, it is possible to make the intra-nuclear-reactor working apparatus  20  submerge and surface or become pressed against the lower surface of the shroud support plate with a simplified structure. 
   In this embodiment, preferably the traveling wheels  24  are rubber wheels having a shape of a truncated cone that are fitted in position with the larger diameter side facing downward. With this arrangement, it is possible to apply an upwardly displacing force to the apparatus as the traveling wheels  24  are pressed against a wall surface and driven to rotate. 
   Then, along with the buoyancy of the ballast tank, it is possible to firmly press the apparatus against the lower surface of the shroud support plate so that the apparatus can securely move horizontally along the shroud support plate. 
   Second Embodiment 
     FIG. 7  shows the second embodiment of intra-nuclear-reactor working apparatus according to the present invention. The components of this embodiment that are same as or similar to those of the first embodiment are denoted respectively by the same reference symbols and will not be described in detail any further. 
   This embodiment differs from the first embodiment illustrated in  FIG. 2  in that the drive mechanism  32  for supporting the working equipment  30  and the float  29   b  includes two links that are arranged adjacently in a horizontal direction. Otherwise, this embodiment is identical with the first embodiment. 
   Third Embodiment 
   Now, the third embodiment of the present invention will be described below by referring to  FIGS. 8 and 9 . The components of this embodiment that are same as or similar to those of the first embodiment are denoted respectively by the same reference symbols and will not be described in detail any further. 
   As shown in  FIGS. 8 and 9 , an upper grid plate  43  having an opening and a reactor core support plate  3  having an opening are arranged in the pressure vessel  2 . The intra-nuclear-reactor working apparatus  20  is led to an area located under the shroud support plate  7  by way of either of two routes  44 ,  145 , one for accessing the area under the shroud support plate  7  from the inner surface side of the shroud  100 , passing through the opening of the upper grid plate  43  and the opening of the reactor core support plate  3 , and one for accessing the area under the shroud support plate  7  from the outer surface side of the shroud  100 , passing through the access hole  46   a.    
   This embodiment can carry out any of various works on the intra-nuclear-reactor structures in the pressure vessel  2  that is immersed in water in a nuclear reactor regardless of the intra-nuclear-reactor environment. More specifically, it can be used to carry out any of various works on the H8 horizontal weld line  9  that is the weld line of the shroud support cylinder  5  and the shroud support plate  7 , the H9 horizontal weld line  10  that is the weld line of the pressure vessel  2  and the shroud support plate  7 , the H10 weld line  11  that is the weld line of the shroud support legs  6  and the shroud support cylinder  5 , the H11 weld line  12  that is the weld line of the shroud support legs  6  and the pressure vessel  2 , the AD-2 weld line  13  that is the weld line of the jet pump  8  and the shroud support plate  7 . 
   For instance, if all the control rod guide tubes  141  and the fuel are installed and it is not possible to take the access route  44  leading to an area under the shroud support plate  7 , it is possible to take off the access hole cover  146  and take the access route  145 . 
   As shown in  FIGS. 10 and 11 , the access hole  46   a  arranged in the pressure vessel  2  is covered by the access hole cover  146 . The access hole cover  146  is rigidly secured to the peripheral edge  46   b  of the access hole  46   b  by means of a total of six bolts (binding sections)  50  and a retainer  52  is arranged between the access hole cover  146  and each of the nuts  51 . 
   Each of the bolts  50  is engaged with a nut  51  and the stoppers  53  that operate as anti-revolution means are formed by using spring mechanisms. Thus, the bolts  50  can be fitted and removed with ease. 
   Since the stopper  53  of each of the bolts  50  is formed by using a spring mechanism  53 , the access hole cover  146  can be fitted and removed with ease by means of a handling jig that is exclusively designed as anti-revolution key. With this arrangement, it is possible to easily carry out operations including inspections, polishing, washing with water, water jet peening, laser peening for preventive maintenance, and repairing operations such as welding in an area located below the shroud support plate  7  by removing the access hole cover  146  if the reactor is loaded with the fuel (not shown) and the control rod guide tubes  141  in the inside. 
   Fourth Embodiment 
   Now, the fourth embodiment of intra-nuclear-reactor working apparatus according to the present invention will be described below. In this embodiment, the mechanism constituting members and the strength holding members of the intra-nuclear-reactor working apparatus and the working equipment are formed by using a polymeric resin material. 
   Specific examples of materials that can be used for this embodiment include polyamide type resins, polyimide type resins, polyether-ether-ketone resins and polyether-sulfone-resins that are excellent in terms of resistance against radioactive rays, water-absorbing property, mechanical strength and thermal resistance. All or part of these materials may be used for the above mechanism composing members and the strength holding members. 
   Thus, with this embodiment, it is possible to replace polymeric resin materials in place of metal materials in order to reduce the weight of the various pieces of equipment, such as an intra-nuclear-reactor working apparatus or working equipment in water. As a result, the ballast tank can be dimensionally reduced to consequently reduce the overall dimensions of the apparatus. As the apparatus is made lightweight and downsized, it can be handled easily and it can pass through narrow areas so that the reliability of operation of the apparatus is also improved. 
   The present invention is not limited to the above-described embodiments, which may be modified in various different ways without departing from the scope of the present invention. 
   For example, inspection results may be displayed on a display apparatus. 
   For example, while the above-described embodiments of intra-nuclear-reactor working apparatus and working method are adapted to be used in nuclear reactors, the present invention can broadly be applied various working apparatus and various working methods. 
   Additionally, while the above-described embodiments of working apparatus and working method are adapted to operations in water, they can be modified in various different ways as pointed out below. For example, while the operation mechanisms including the adhering/traveling modules  22  and related mechanisms may be housed in a water-tight case or the like and adapted to perform adhering/traveling operations in water, the working equipment of a working apparatus according to the present invention may be separated from them and put in air so as to operate in air. As another example, the adhering/traveling modules  22  and the thrusters  41  may be dimensionally raised to use a large drive source and a large drive mechanism for the thrusters  41  so that the thrusters  41  may acquire a sufficiently large air flow rate to produce a large adhering force in air as they are driven to rotate at high speed. With such an arrangement, a working apparatus and a working method according to the present invention may be applied to works in air.