Patent Number: 
Section: claims

1. An installation structure for installing control rod drive mechanisms and cable sealing units in a nuclear reactor pressure vessel, the installation structure comprising:a sealing flange having a ring shape and being hermetically coupled between an upper pressure vessel and a lower pressure vessel of the nuclear reactor pressure vessel;a cylindrical tube extending downward vertically from an internal edge of the sealing flange; anda support plate provided horizontally to block a lower end portion of the cylindrical tube,wherein a plurality of mounting holes that penetrate through the sealing flange horizontally are arranged in the sealing flange with predetermined intervals therebetween along a circumferential direction, the cable sealing units are inserted and mounted in the plurality of mounting holes, and the control rod drive mechanisms are installed on the support plate to be supported,wherein a plurality of low temperature coolant passages that vertically penetrate through the sealing flange are provided in the sealing flange with predetermined intervals therebetween along a circumferential direction, andwherein a low temperature coolant passage connecting recess having a ring shape that connects upper portions of the plurality of low temperature coolant passages to one another and communicates with the plurality of low temperature coolant passages is formed in an upper surface of the sealing flange. 2. The installation structure of claim 1, wherein a plurality of high temperature coolant passages are formed in the support plate so as to vertically penetrate through the support plate. 3. The installation structure of claim 2, wherein the plurality of low temperature coolant passages are located at an outer portion of the cylindrical tube, and the plurality of high temperature coolant passages are located at an inner portion of the cylindrical tube. 4. The installation structure according to claim 1, wherein a plurality of control rod driving shaft insertion holes, in which control rod driving shafts elevated by the control rod drive mechanisms are inserted, are formed in the support plate so as to vertically penetrate through the support plate. 5. The installation structure of claim 4, wherein a plurality of installation recesses, in which a lower end portion of the control rod drive mechanism is inserted, are formed in an upper surface of the support plate, and the control rod driving shaft insertion hole is formed at a center portion of each of the plurality of installation recesses. 6. The installation structure according to claim 1, wherein a plurality of cables are led into the nuclear reactor pressure vessel through one cable sealing unit mounted in each of the plurality of mounting holes. 7. The installation structure of claim 6, wherein the cable sealing unit comprises a penetration tube that is fixedly inserted in the mounting hole of the sealing flange, a thimble inserted to the penetration tube, and a guide tube inserted into the thimble, and the plurality of cables are inserted to the guide tube.