Patent Number: 053316754
Section: description

DETAILED DESCRIPTION OF THE EMBODIMENTS Hereinafter, details of the present invention is explained based on embodiments by referring to drawings. First, the constitution of a reactor core comprising fuel assemblies 8, a CR 6, a CRD 4 and a FS 7 in a reactor vessel is explained. FIG. 1 shows the internal constitution in the reactor vessel of a BWR, FIG. 2 is a bird's-eye view of part II in FIG. 1, FIG. 3 is an assembling drawing of the fuel assemblies 8, the CR 6, the CRD 4 and the FS 7, and FIG. 4 is an enlarged view of part IV in FIG. 2 which is shown partially by a sectional view. As shown in FIG. 1, in a BWR, constitution components are installed in the reactor vessel 1. A reactor core support plate 3 is fixed to a reactor core shroud 2 constructed with the reactor vessel 1 in a body. The CRD 4 is provided in the bottom part of the reactor vessel 1. As shown in FIG. 2 and FIG. 3, a CR guide tube 5 is provided above the CRD 4, projecting above the reactor core support plate 3, fixed by engaging pins 3a provided on the reactor core support plate 3 into connection holes 5a of the control guide tube 5. In the CR guide tube 5, the CR 6 having cruciform section is connected to the top of the CRD 4 by the bayonet coupling as shown in FIG. 5(a) and 5(b), FIG. 6(a), 6(b), 6(d) and 6(e), and in the upper part of the CR guide tube 5, the FS 7 for supporting four fuel is fixed by engaging the pins 3a into connection holes assemblies 8 is provided. As shown in FIG. 4, the FS 7 7a for preventing the FS 7 from rotating. The fuel assemblies 8 are positioned by inserting the bottom part of the fuel assemblies 8 into holes for fuel support 7b and the top parts of the fuel assemblies 8 are fixed by the upper grid plate 9. Next, the constitution of the bayonet coupling 10 for connecting the CR 6 and the CRD 4 is explained. FIG. 5(a) and 5(b) show the constitution of the bayonet coupling, FIG. 5(a) is a bird's-eye view of the connection part and FIG. 5(b) is an enlarged view of the part B in FIG. 5(a). FIG. 6(a)-6(f) show the procedures for disconnecting the bayonet coupling 10, FIG. 6(a), 6(b) and 6(c) are vertical sectional views of the bayonet coupling, and FIG. 6(d), 6(e) and 6(f) are a D--D sectional view of FIG. 6(a), a E--E sectional view of FIG. 6(b) and a F--F sectional view of FIG. 6(c), respectively. As shown in FIG. 6(a) and 6(b), the bayonet coupling 10 consists of a coupling socket 11 provided at the bottom of the CR 6 and a coupling spud 12 provided at the top of the CRD 4. Convex parts 13 are arranged by 90 degrees of interval in the circumferential direction at the upper part of the coupling spud 12 and convex parts 15 are arranged by 90 degree of intervals at the inside face of the coupling socket 11. As shown in FIG. 6(b) and 6(e), the connection of the convex parts 13 and 15 is disconnected by rotating the coupling socket 11 by 45 degrees. Next, the procedures for control rod exchanging is explained by referring to FIG. 7. The steps 101-112 of FIG. 7 indicate each procedure for exchanging the control rod. FIG. 8(a)-8(e) are drawings of the upper grid plate 9 viewed from above and correspond to the steps from the step 101 of taking out the fuel assemblies 8 to the step 105 of taking out control rod blade guides 16, respectively. Coupling and disconnecting the bayonet coupling 10 are implemented after fully withdrawing the CR 6 downward. After the step 105, the step 106 for taking off the CR 6 and the step 107 for mounting the CR 6 are implemented. Conventionally, the three sub-steps in the dotted line box of each step 106 and 107 are not continuously implemented and the independent procedure is needed for implementing each of the three sub-steps. Especially, for the tasks for taking off the FS 7 and the CR 6, the tasks of attaching or taking off the exclusive equipment for the FS 7 or the CR 6 and the tasks of getting down or lifting the exclusive equipment are needed in the sub-steps. On the other hand, by using the apparatus and the method for handling the CR 6 of the present invention, the three sub-stages in each of the steps 106 and 107 are continuously implemented as a step. Next, the constitution of the control rod handling apparatus as an embodiment of the present invention is explained by referring to FIG. 9-12. FIG. 9 shows the constitution of the control rod handling apparatus of the embodiment. The control rod handling apparatus 100 comprises a fixing part 20, a CR handling part 21, a FS handling part 22, a vertically moving part 23 and a rotating part 23 of which functions are mentioned after. The fixing part 20 having dual constitution comprises a body 30 of the fixing part 20 inside which a rotating part 24 is provided, a member for connection 31 provided at the top face of the body 30 and attached to a wire rope 110 hanging from the subsidiary hoist of the fuel exchange apparatus not shown in a figure, and guides 32 provided at the bottom face of the body 30 to be seated at the top face of the upper grid plate 9 and to be supported by the upper grid plate 9 for preventing the control rod handling apparatus 100 from rotating. The CR handling part 21 provided at the bottom part of the fixing part 20 and having the same cruciform section as the CR 6, comprises a CR handling body 33 at the bottom of which a disk 33a is provided, a CR grasping instrument 34 provided at the bottom of the disk 33a for grasping the CR 6, a member 35 for detection of seating of the CR handling part 21 at the CR 6 to detect seating of the CR handling part 21 at the top of the CR 6 fully withdrawn and a sensor 35A for detection of seating of the CR handling part 21 at the CR 6 provided at the bottom face of the disk 33a. As shown in FIG. 10 by the sectional view in XII--XII direction of FIG. 9, the CR grasping instrument 34 comprises a CR hook 51 supported by a pin 53 in the center of the bottom face of the member 35 for detection of seating of the CR handling part 21 at the CR 6 and an air cylinder 52 connected to the top face of the member 35 by a pin 54. The CR hook 51 is connected to the bottom of the air cylinder 52 and grasps the CR 6 by revolving on the fulcrum of the pin 53 by the action of the air cylinder 52. The member 35 for detection of seating of the CR handling part 21 at the CR 6 comprises the disk form upper part and the cruciform lower parts the four bottoms of which are nicked for positioning the CR handling part 21 to the CR 6. The member 35 for detection of seating of the CR handling part 21 at the CR 6 is connected to the disk 33a at the bottom of the CR handling body 33 by engaging the projection part 35a at the top of the member 35 into a connection cover 55 and has ability of some up-and-down motion by a bush 56 and a spring 57. When the member 35 for detection of seating of the CR handling part 21 at the CR 6 is seated at the CR 6, the member 35 is pushed up and the projection part 35a goes up inside the connection cover 55 as pushing the spring 57. At the same time, the top face of the member 35 pushes the tip of the sensor 35A for detection of seating of the CR handling part 21 at the CR 6 which generates a signal of seating of the CR handling part 21 at the CR 6. A circuit not shown in a figure confirms that the CR handling part 21 is seated at the CR 6 by accepting the signal. The FS handling part 22 comprises a FS handling body 36 having a cruciform hole in its center so that the CR handling body 33 penetrates the hole and the FS handling part 22 can move vertically outside the CR handling body 33, a FS grasping instrument 37 provided at the bottom face of the FS handling body 36 and having hooks 61 which are inserted into the holes for fuel support 7b shown in FIG. 3 and grasps the FS 7, positioning pins 38 provided at the bottom face of the FS handling body 36 which are inserted into the holes for fuel support 7b and position the FS handling part 22, a member 39 for detection of seating of the FS handling part 22 at the FS 7 having the same cruciform hole in its center as the FS handling body 36 and detecting that the FS handling part 22 is seated at the top face of the FS 7, and a sensor 39A for detection of seating of the FS handling part 22 at the FS 7 provided at the bottom face of the member 39. The FS grasping instruments 37 and the positioning pins 38 are provided in pairs, each pair of which are diagonally located, respectively. As shown in FIG. 11 by the sectional view in XIII--XIII direction of FIG. 9, the FS grasping instrument 37 comprises two FS hooks 61 respectively divided into two pieces the interval between which tapers downward, a FS hook support member 62 having cylindrical shape and provided at the bottom face of the member 39 for detection of seating the FS handling part 22 at the FS 7, an air cylinder 63 provided at the bottom face of the member 39 and inside the FS hook support member 62, and a shaft vertically moving by operation of the air cylinder 63. After the FS hooks 61 are inserted into the holes for fuel support 7b, the divided bottom parts of each FS hook 61 are spread out when the shaft 64 is lowered along the inside faces of each FS hook 61 tapering downward. Then the FS 7 is grasped by the spread bottom parts of the FS hooks 61. The member 39 for detection of seating of the FS handling part 22 at the FS 7 is connected to the FS handling body 36 at the top of which a projection part 39a is engaged into a connection cover 65 and has ability of some up-and-down motion by a bush 66 and a spring 67. When the member 39 for detection of seating of the FS handling part 22 at the FS is seated at the FS 7, the member 39 is pushed up and the projection part 39a goes up inside the connection cover 65 as pushing the spring 67. At the same time, the top face of the member 39 pushes the tip of the sensor 39A for detection of seating of the FS handling part 22 at the FS 7 which generates a signal of seating of the FS handling part 22 at the FS 7. A circuit not shown in a figure confirms that the FS handling part 22 is seated at the FS 7 by accepting the signal. The vertically moving part 23 comprises a pair of racks for vertical motion 40 penetrating the FS handling part 22 provided at the bottom of the fixing part 20, a pair of motors for vertical motion 41, and a pair of pinions for vertical motion 42 provided to the pair of motors 41, respectively. The rotating part 24 as shown in FIG. 12 partially by the sectional drawing and viewed in XIV direction of FIG. 9, comprises a rack for rotation 43, a member for rotation 44 connected to the bottom of the rack for rotation 43 and to the CR handling part 21, a motor for rotation 45 provided at the fixing part, and a pinion for rotation 44 gearing with the rack for rotation 43 attached to a shaft of the motor for rotation 45. The member for rotation 44 comprises two large radius of disks sandwiching a small disk in them and prevents itself from falling by engaging the member 44 into a circular hole provided at the top face of the lower part of the body 30 of the fixing part 20. The CR handling part 21, the FS handling part 22 and the vertically moving part 23 are rotated by the member for rotation 44 which is also rotated by the motor 45, the pinion 46 and the rack 43. Next, a method as an embodiment for taking off the CR 6 corresponding to the step 106 of FIG. 7 by using the above-mentioned CR handling apparatus 100 is explained by referring to FIG. 13-17. The procedures of getting down the CR handling apparatus 100 and the FS handling part 22 are as follows. As shown in FIG. 13, the member for connection 31 is connected to the tip of the wire rope 110 hanged from the subsidiary hoist of the fuel exchange apparatus and the CR handling apparatus 100 is got down into the reactor core by unwinding the wire rope 110 with the subsidiary hoist. The motion of getting down the CR handling apparatus 100 is stopped when the bottoms of the guides 32 are seated at the top face of the upper grid plate 9. The FS handling part 22 is lowered to the FS 7 as shown by an arrow in FIG. 13 by using the motors 41, the pinions 42 and the racks 40 of the vertically moving part 23. And the motion of lowering the FS handling part 22 is stopped when the member 39 for detection of seating of the FS handling part 22 at the FS 7 is seated at the top face of the FS 7. At that time, the positioning of the FS handling part 22 to the FS 7 is done by inserting the positioning pins 38 diagonally allocated at the bottom face of the FS handling body 36 into the holes for fuel support 7b. The procedures of taking of the FS 7 are as follows. After the FS 7 is grasped by the FS grasping instrument 37 diagonally provided at the bottom face of the FS handling body 39, the FS handling part 22 is lifted above the upper grid plate 9 as shown by an arrow in FIG. 14, by operating the vertically moving part 23. In the procedures, since the horizontal direction of the FS 7 is kept as originally positioned, the FS 7 does not interfere with the upper grid plate 9 in taking off the FS 7 through the upper grid plate 9. The procedures of grasping the CR 6 and disconnecting the connection of the bayonet coupling are as follows. As shown in FIG. 15, the CR 6 is grasped by operating the CR grasping instrument 34. And, as shown in FIG. 16, the connection of the bayonet coupling between the CR 6 and the CRD 4 is disconnected by rotating the CR handling part 21, the FS handling part 22 and the vertically moving part 23 together by 45 degrees, by operating the rotating part 24. The procedures of taking out the CR 6 above the upper grid plate 9 are as follows. As shown in FIG. 17, the CR handling apparatus 100 grasping the FS 7 and the CR 6 is lifted by winding the wire rope 110 with the subsidiary hoist of the fuel exchange apparatus, and the CR 7 is taken out from the reactor core apart from the CRD 4. By the above-mentioned procedure, the CR taking out work comprising the steps of taking off the FS 7, disconnecting the CR 6 and the CRD 4 and taking out the CR is completed. And the step 107 of attaching a new CR as shown in FIG. 7 can be done by the reverse procedures to the above-mentioned procedures for taking out the CR 6 and the FS 7. Next, an another method as an embodiment for taking off a CR 6 by using of the above-mentioned CR handling apparatus 100 is explained by referring to FIGS. 18-20. The procedures of getting down the CR handling apparatus 100 and lowering the FS handling part 22 are the same procedures as the previous method. After the procedures, the FS 7 is taken off and lifted by the position below the upper grid plate 9 as shown in FIG. 18. And the CR handling part 21, the FS handling part 22 and the vertically moving part 23 are rotated by 45 degrees, then the connection by the bayonet coupling between the CR 6 and the CRD 4 is disconnected. The CR handling apparatus 100 grasping the FS 7 and the CR 6 is lifted by winding the wire rope 110 with the subsidiary hoist of the fuel exchange apparatus and stopped when the top part of the FS handling part 22 reaches the position right bellow the upper grid plate 9. The reason why lifting the CR handling apparatus is stopped at the position is explained as follows. FIG. 19(a) and 19(b) are figures of the FS 7 and the upper grid plate 9 viewed from above. As shown in FIG. 19(a), the FS 7 does not interfere with the upper grid plate 9 when the horizontal direction of the FS 7 is kept as originally positioned. In the second method for handling the CR 6, since the FS 7 is also rotated by 45 degrees in rotating the CR 6, the CR handling part 21 and the FS handling part 22 for disconnecting the CR 6 and the CRD 4, passing the FS 7 rotated by 45 degrees through the upper grid plate 9 is obstructed by interference between the FS 7 and the upper grid plate 9 as shown in FIG. 19(b). In order to avoid the interference, before passing the FS 7 through the upper gird plate 9, the FS 7 is rotated by 45 degrees in the reverse direction to the first rotation, as shown in FIG. 20. In the first method for handling the CR 6, before rotating the CR 6 for disconnecting the connection, the FS 7 is taken out above the upper grid plate 9. Therefore, the above-mentioned interference does not arise. The procedures of taking out the FS 7 and the CR 6 above the upper rid plate 9 are as follows. The FS handling part 22 is lifted above the upper grid plate 9. And the CR handling apparatus 100 grasping the FS 7 and the CR 6 is lifted by winding the wire rope 110 with the subsidiary hoist of the fuel exchange apparatus and then the CR 6 is taken out above the upper gird plate 9. By the above-mentioned procedures, the CR taking out work comprising the steps of taking off the FS 7, disconnecting the connection of the CR 6 and the CRD 4 and taking out the CR 6 is completed. And attaching a new CR can be done by the reverse procedures to the above-mentioned procedures for taking out the CR 6. As has been explained in the foregoing, according to the present invention, taking off the FS disconnecting the connection by the bayonet coupling between the CR and the CRD and taking out the CR from the reactor core are continuously implemented without any change of reactor core structures, which considerably shorten the time for the CR exchange.