A repair device for underwater repair of a hole in a nuclear reactor part includes a holder (32), a cutting tool (22) held by the holder (32) and having at least one cutting tooth (70) for remachining an inner surface of the hole. The cutting tool (22) has a suction channel (44) extending into the cutting tool (22) between at least one inlet opening (46) and at least one outlet opening (48), a drive shaft (34) for rotating the cutting tool (22), the drive shaft (34) being held by the holder (32), and a suction tube (36) connected to the holder (32) and fluidly connected to the outlet opening (48) of the suction channel (44).

A damping area or “dash pot” on the upper ends of control rods absorb energy from dropped control rod assemblies without narrowing the diameter of guide tubes. As a result, coolant can freely flow through the guide tubes reducing boiling water issues. The dampening area reduces a separation distance between an outside surface of the control rod and an inside surface of the guide tubes decelerating the control rods when entering a top end of the guide tubes. In another example, the dampening area may be located on a drive shaft. The dampening area may have a larger diameter than an opening in a drive shaft support member that decelerates the drive shaft when dropped by a drive mechanism.

A method is for manufacturing a nuclear fuel assembly (2) comprising nuclear fuel rods (4) arranged in a bundle and a skeleton (6) supporting the fuel rods (4). The method comprise the steps of inserting fuel rods (4) into the skeleton (6) to obtain a fuel assembly (2) and packaging the fuel assembly (2) in view of transportation. The steps are being performed in a same nuclear fuel assembly manufacturing plant (20), preferably in a same nuclear fuel assembly manufacturing building (60).

An entire nuclear fuel core comprising a plurality of fuel assemblies is preassembled in a nuclear fuel cartridge having a self-supporting unitary support structure. During a refueling operation, the unitary support structure is moved into a nuclear reactor vessel. The unitary support structure may be formed by top and bottom core plates coupled together by vertically-oriented connecting rods which compress the fuel assemblies therebetween. A plurality of reflector wall segments circumscribe the core and are the coupled together between the core plates by the connecting rods which are coupled to the core plates. The connecting rods may extend through the wall segments.

Portable nuclear fuel cartridge comprising a unitary support structure and plurality of nuclear fuel assemblies that collectively form a nuclear fuel core. Control rod drive system for a nuclear reactor. A nuclear steam supply system having a shutdown system for removing residual decay heat generated by a nuclear fuel core. A nuclear reactor including a cylindrical body having an internal cavity, nuclear fuel core, and a shroud disposed in the cavity. A nuclear reactor cooling system with passive cooling capabilities operable during a loss-of-coolant accident (LOCA) without available electric power.

The present invention relates to a top nozzle and a nuclear reactor in which an in-core instrument, which is supposed to be inserted through a top head of a nuclear reactor, is inserted through a guide pin for an upper core plate. In a nuclear reactor including guide pins for aligning a top nozzle for a nuclear fuel assembly with an upper core plate of a nuclear reactor, a guide hole (210) is axially formed through the guide pins (200) and in-core instruments (10) are inserted through the guide holes (210).

Disclosed is a system for separating and coupling a top nozzle of a nuclear fuel assembly. There is provided a lock insert configured to support the top nozzle of the nuclear fuel assembly by being coupled to a guide hole provided in a flow channel plate of the top nozzle, the lock insert including: a body in a hollow shape; and an insertion part provided on a top portion of the body and inserted into the guide hole, wherein a circumference of the insertion part is variable in size, thereby being capable of being inserted into the guide hole. Accordingly, disassembly and reassembly of the top nozzle of the nuclear fuel assembly and the lock insert are simplified, thereby simplifying and reducing the number of processes involved therein. Accordingly, the system is effective for maintenance and repair of the nuclear fuel assembly.

A separating and coupling system of a nuclear fuel assembly top nozzle. The system includes a top nozzle; a flow channel plate provided at a lower portion of the top nozzle and allowing coolant to pass therethrough; a guide hole provided in the flow channel plate; a lock insert in a hollow shape including an insertion part configured to be inserted into the guide hole; and a separation member configured to separate the lock insert from the guide hole. The circumference of the insertion part is variable in size, thereby being capable of being inserted into and separated from the guide hole. Accordingly, disassembly and reassembly of the top nozzle of the nuclear fuel assembly and the lock insert are simplified, thereby simplifying the process and reducing the number of processes. The system is effective for maintenance and repair of the nuclear fuel assembly.

A vacuum micro-electronics device that utilizes fissile material capable of using the existing neutron leakage from the fuel assemblies of a nuclear reactor to produce thermal energy to power the heater/cathode element of the vacuum micro-electronics device and a self-powered detector emitter to produce the voltage/current necessary to power the anode/plate terminal of the vacuum micro-electronics device.

The present invention relates to a top nozzle and a nuclear reactor in which an in-core instrument, which is supposed to be inserted through a top head of a nuclear reactor, is inserted through a guide pin for an upper core plate. In a nuclear reactor including guide pins for aligning a top nozzle for a nuclear fuel assembly with an upper core plate of a nuclear reactor, a guide hole (210) is axially formed through the guide pins (200) and in-core instruments (10) are inserted through the guide holes (210).