Abstract: Provided is a secondary shutdown structure of a nuclear reactor, which uses sliding doors, and more particularly, to a secondary shutdown structure of a nuclear reactor, which uses sliding doors and is capable of shutting down a nuclear reactor reliably with a simple structure without using a boric acid solution.

Abstract: Provided is an installation structure for installing control rod drive mechanisms and cable sealing units in a nuclear reactor pressure vessel. The installation structure includes: a sealing flange having a ring shape and being hermetically coupled to 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; and a support plate provided horizontally to block a lower end portion of the cylindrical tube. A plurality of mounting holes that penetrate through the sealing flange horizontally are arranged in the sealing flange with a predetermined interval 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.

Abstract: An apparatus for detecting a position of a control rod includes a control rod driving shaft having an outer circumferential surface on which position information is marked, a mirror configured to reflect the position information, and a detector configured to detect a position of the control rod driving shaft from the position information reflected from the mirror, when the control rod driving shaft moves vertically.

Abstract: A magnetic jack type in-vessel control element drive mechanism includes: an upper coil assembly which includes a first sleeve configured to coaxially wrap a control element drive shaft, a first coil, and a first coil housing which is externally coupled to the first sleeve; a lower coil assembly which includes a second sleeve configured to coaxially wrap the control element drive shaft, a second coil, and a second coil housing which is externally coupled to the second sleeve, wherein the lower coil assembly is located under the upper coil assembly, a connecting member which connects the upper coil assembly and the lower coil assembly; a support tube which extends downward from the lower coil assembly; a motor assembly which is located between the control element drive shaft, and the first and second sleeves; and an anti-separation cap which prevents separation of the motor assembly.

Abstract: A sealing mechanism for a reactor vessel (RV) cable penetration tube improves the functional and structural integrity of a cable inserted in an RV through a penetration tube due to use of a precise thimble. The sealing mechanism includes a penetration tube configured to penetrate an RV from an outside to an inside thereof and having a penetration hole for communication with the inside of the RV, a cable configured to be inserted in the RV through the penetration hole of the penetration tube, and a thimble placed between the cable and the penetration tube, wherein a dimple groove portion is provided on the thimble in a direction from an outer surface of the penetration hole toward the cable.

Abstract: Provided is a secondary shutdown structure of a nuclear reactor, which uses sliding doors, and more particularly, to a secondary shutdown structure of a nuclear reactor, which uses sliding doors and is capable of shutting down a nuclear reactor reliably with a simple structure without using a boric acid solution.

Abstract: Provided is an installation structure for installing control rod drive mechanisms and cable sealing units in a nuclear reactor pressure vessel. The installation structure includes: a sealing flange having a ring shape and being hermetically coupled to 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; and a support plate provided horizontally to block a lower end portion of the cylindrical tube. A plurality of mounting holes that penetrate through the sealing flange horizontally are arranged in the sealing flange with a predetermined interval 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.

Abstract: A sealing mechanism for a reactor vessel (RV) cable penetration tube improves the functional and structural integrity of a cable inserted in an RV through a penetration tube due to use of a precise thimble. The sealing mechanism includes a penetration tube configured to penetrate an RV from an outside to an inside thereof and having a penetration hole for communication with the inside of the RV, a cable configured to be inserted in the RV through the penetration hole of the penetration tube, and a thimble placed between the cable and the penetration tube, wherein a dimple groove portion is provided on the thimble in a direction from an outer surface of the penetration hole toward the cable.

Abstract: A magnetic jack type control element drive mechanism for precision position control of a control element assembly, satisfies the following conditions: D1=D2=P+D5; D3=P×2; D4=D3×(N?½), (N is an arbitrary natural number), wherein D1 represents a lift gap of the upper motor assembly; D2 represents a lift gap of the lower motor assembly; D3 represents a space width between tips of adjacent teeth of the drive shaft; D4 represents a gap between an upper latch and a lower latch; P represents pitch that is a distance of ascent or descent of the drive shaft; and D5 represents a margin which is a separation space between the teeth and the upper latch or the lower latch when the upper latch or the lower latch is inserted into the teeth of the drive shaft.

Abstract: The cooling duct assembly for a control element drive mechanism (CEDM) includes a skirt that is combined on a circumference of a reactor head and has first air channels in an inner side thereof; a lower duct that is combined with an upper side of the skirt, has second air channels that are connected to the first air channels, and is disposed to surround a circumference of the CEDM; and an upper duct, an edge of which is combined with the cooling air handling device, and other edge of which is detachably combined with the lower duct, wherein air that cools the CEDM is discharged to the outside after sequentially passing the first air channels, the second air channels, the upper duct, and the cooling air handling device, and the upper duct separated from the lower duct is lifted together with the cooling air handling device.

Abstract: An apparatus for detecting a position of a control rod includes a control rod driving shaft having an outer circumferential surface on which position information is marked, a mirror configured to reflect the position information, and a detector configured to detect a position of the control rod driving shaft from the position information reflected from the mirror, when the control rod driving shaft moves vertically.

Abstract: A magnetic jack type control element drive mechanism for precision position control of a control element assembly, satisfies the following conditions: D1=D2=P+D5; D3=P×2; D4=D3×(N?½), (N is an arbitrary natural number), wherein D1 represents a lift gap of the upper motor assembly; D2 represents a lift gap of the lower motor assembly; D3 represents a space width between tips of adjacent teeth of the drive shaft; D4 represents a gap between an upper latch and a lower latch; P represents pitch that is a distance of ascent or descent of the drive shaft; and D5 represents a margin which is a separation space between the teeth and the upper latch or the lower latch when the upper latch or the lower latch is inserted into the teeth of the drive shaft.

Abstract: A magnetic jack type in-vessel control element drive mechanism includes: an upper coil assembly which includes a first sleeve configured to coaxially wrap a control element drive shaft, a first coil, and a first coil housing which is externally coupled to the first sleeve; a lower coil assembly which includes a second sleeve configured to coaxially wrap the control element drive shaft, a second coil, and a second coil housing which is externally coupled to the second sleeve, wherein the lower coil assembly is located under the upper coil assembly, a connecting member which connects the upper coil assembly and the lower coil assembly; a support tube which extends downward from the lower coil assembly; a motor assembly which is located between the control element drive shaft, and the first and second sleeves; and an anti-separation cap which prevents separation of the motor assembly.

Abstract: The cooling duct assembly for a control element drive mechanism (CEDM) includes a skirt that is combined on a circumference of a reactor head and has first air channels in an inner side thereof; a lower duct that is combined with an upper side of the skirt, has second air channels that are connected to the first air channels, and is disposed to surround a circumference of the CEDM; and an upper duct, an edge of which is combined with the cooling air handling device, and other edge of which is detachably combined with the lower duct, wherein air that cools the CEDM is discharged to the outside after sequentially passing the first air channels, the second air channels, the upper duct, and the cooling air handling device, and the upper duct separated from the lower duct is lifted together with the cooling air handling device.

Abstract: Provided is a modular reactor head area assembly. The modular reactor head area assembly is installed on a reactor head, and includes: a seismic support structure that performs functions of lifting, moving and reinstallation of the reactor head and control rod driving apparatuses, cooling of the control rod driving apparatuses, shielding of missile parts, and supporting with respect to a seismic load, and disperses a load applied to the control rod driving apparatuses; an upper module that is an assembly of components located at an upper portion of the seismic support structure for the control rod driving apparatuses; and a lower module that is an assembly of components located at a lower portion of the seismic support structure for the control rod driving apparatuses. The upper module and the lower module are 252 detachably coupled to each other so that maintenance of the control rod driving apparatus can be performed easily.

Abstract: A cooling unit cooling a coil assembly that generates electromagnetic force for driving a nuclear reactor control rod, and including a coil surrounding a driving shaft of the nuclear reactor control rod so as to generate the electromagnetic force; a coil housing surrounding the coil so as to enclose the coil; a cooling shroud-shell forming a cooling flow path between the cooling shroud-shell and the coil housing, whereby a cooling fluid for cooling heat that is generated in the coil passes through the cooling flow path; and a plurality of cooling fins disposed on the cooling flow path in a radial direction so as to allow heat to be effectively exchanged between the coil and the cooling fluid that flows through the cooling flow path.

Abstract: A cooling unit cooling a coil assembly that generates electromagnetic force for driving a nuclear reactor control rod, and including a coil surrounding a driving shaft of the nuclear reactor control rod so as to generate the electromagnetic force; a coil housing surrounding the coil so as to enclose the coil; a cooling shroud-shell forming a cooling flow path between the cooling shroud-shell and the coil housing, whereby a cooling fluid for cooling heat that is generated in the coil passes through the cooling flow path; and a plurality of cooling fins disposed on the cooling flow path in a radial direction so as to allow heat to be effectively exchanged between the coil and the cooling fluid that flows through the cooling flow path.

Abstract: Provided is a modular reactor head area assembly. The modular reactor head area assembly is installed on a reactor head, and includes: a seismic support structure that performs functions of lifting, moving and reinstallation of the reactor head and control rod driving apparatuses, cooling of the control rod driving apparatuses, shielding of missile parts, and supporting with respect to a seismic load, and disperses a load applied to the control rod driving apparatuses; an upper module that is an assembly of components located at an upper portion of the seismic support structure for the control rod driving apparatuses; and a lower module that is an assembly of components located at a lower portion of the seismic support structure for the control rod driving apparatuses. The upper module and the lower module are 252 detachably coupled to each other so that maintenance of the control rod driving apparatus can be performed easily.

Abstract: An ESD protection circuit including an NMOS transistor connected between an input/output pad and a ground. The NMOS transistor has a parasitic bipolar transistor, and at least one diode is connected between the input/output pad and the NMOS transistor.

Abstract: A multi-finger type electrostatic discharge protection circuit is disclosed. In an NMOS type ESD protection circuit, a pair of gates are formed in parallel with each other in one of multiple active regions so as to enable all the gate fingers in the active regions to perform npn bipolar operations uniformly. The present invention discharges an ESD pulse effectively by forming one or more additional n+ (or p+) type active regions, which are connected to Vcc (or Vss), between respective active regions.