Abstract: Provided are embodiments of a pressure-compensated load transfer device that includes a plate having a first shaft vertically installed on one side and a second shaft vertically installed on the other side to be coaxial with the first shaft. Also included is a first bellows having an opening in one side to surround the first shaft, with the other side thereof being fixed to the one side of the plate. Further included is a plurality of second bellows each having an opening in one end, with the other end thereof being attached to the other side of the plate. A housing is also included, and the housing includes a high-pressure working hole communicating with the opening of the first bellows and a high-pressure channel coplanar with the high-pressure working hole and communicating with the openings of the second bellows. The plate is back-and-forth movably received in the housing.

Abstract: Provided are embodiments of a pressure-compensated load transfer device that includes a plate having a first shaft vertically installed on one side and a second shaft vertically installed on the other side to be coaxial with the first shaft. Also included is a first bellows having an opening in one side to surround the first shaft, with the other side thereof being fixed to the one side of the plate. Further included is a plurality of second bellows each having an opening in one end, with the other end thereof being attached to the other side of the plate. A housing is also included, and the housing includes a high-pressure working hole communicating with the opening of the first bellows and a high-pressure channel coplanar with the high-pressure working hole and communicating with the openings of the second bellows. The plate is back-and-forth movably received in the housing.

Abstract: A combination of a top nozzle and a guide thimble of a nuclear fuel assembly and, more particularly, a structure for joining an inner-extension tube, the top nozzle and the guide thimble. When an inner-extension tube head, which is provided as a means for facilitating removal of the top nozzle of the nuclear fuel assembly from the guide thimble, is removed from an inner-extension tube body to separate the top nozzle from the nuclear fuel assembly, the inner-extension tube body is prevented from undesirably rotating, so that the guide thimble and the inner-extension tube body can maintain the joined state.

Abstract: A combination of a top nozzle and a guide thimble of a nuclear fuel assembly and, more particularly, a structure for joining an inner-extension tube, the top nozzle and the guide thimble. When an inner-extension tube head, which is provided as a means for facilitating removal of the top nozzle of the nuclear fuel assembly from the guide thimble, is removed from an inner-extension tube body to separate the top nozzle from the nuclear fuel assembly, the inner-extension tube body is prevented from undesirably rotating, so that the guide thimble and the inner-extension tube body can maintain the joined state.

Abstract: A joint structure between a top nozzle and a guide thimble of a nuclear fuel assembly and, more particularly, a structure for joining an inner-extension tube, the top nozzle and the guide thimble. When an inner-extension tube head, which is provided as a means for facilitating removal of the top nozzle of the nuclear fuel assembly from the guide thimble, is removed from an inner-extension tube body to separate the top nozzle from the nuclear fuel assembly, the inner-extension tube body is prevented from undesirably rotating, so that the guide thimble and the inner-extension tube body can maintain the joined state.

Abstract: A joint structure between a top nozzle and a guide thimble of a nuclear fuel assembly and, more particularly, a structure for joining an inner-extension tube, the top nozzle and the guide thimble. When an inner-extension tube head, which is provided as a means for facilitating removal of the top nozzle of the nuclear fuel assembly from the guide thimble, is removed from an inner-extension tube body to separate the top nozzle from the nuclear fuel assembly, the inner-extension tube body is prevented from undesirably rotating, so that the guide thimble and the inner-extension tube body can maintain the joined state.

Abstract: Disclosed herein is a joint structure between a top nozzle and a guide thimble. The joint structure includes an outer guide post, an inner-extension tube head, an inner-extension tube body, a wedge and the guide thimble. The outer guide post is provided with an external thread formed on a lower end thereof. The inner-extension tube head includes an annular retaining part formed on an upper end thereof. An internal thread is formed on a medial portion of the inner-extension tube head. An external thread is formed on each of upper and lower ends of the inner-extension tube body. A stop protrusion is provided under a lower end of the wedge. The wedge is welded to the inner-extension tube body after the top nozzle has been joined with the guide thimble. A stop protrusion receiving depression is formed in the guide thimble.

Abstract: Disclosed herein is a joint structure between a top nozzle and a guide thimble. The joint structure includes an outer guide post, an inner-extension tube head, an inner-extension tube body, a wedge and the guide thimble. The outer guide post is provided with an external thread formed on a lower end thereof. The inner-extension tube head includes an annular retaining part formed on an upper end thereof. An internal thread is formed on a medial portion of the inner-extension tube head. An external thread is formed on each of upper and lower ends of the inner-extension tube body. A stop protrusion is provided under a lower end of the wedge. The wedge is welded to the inner-extension tube body after the top nozzle has been joined with the guide thimble. A stop protrusion receiving depression is formed in the guide thimble.

Abstract: A top nozzle is provided. The top nozzle can include a coupling plate, a perimeter wall and a hold-down spring unit. The coupling plate can be coupled to a guide thimble of the nuclear fuel assembly. The perimeter wall can protrude upwards from the perimeter of the coupling plate. A spring clamp can be provided on the upper surface of the perimeter wall. The hold-down spring unit can be mounted to the upper surface of the perimeter wall in such a way to couple a corresponding end of the hold-down spring unit to the spring clamp. A fastening pin hole can be vertically formed through an upper surface of the spring clamp. A spring insert hole into which the hold-down spring unit can be inserted and formed by electro-discharge machining in an insert direction of the hold-down spring.

Abstract: A guide thimble plug for a nuclear fuel assembly is provided, in which an internal threaded hole is formed through a main body so that the main body is coupled to a bottom nozzle by a screw coupling. An upper insert part is formed in the upper end of the main body. The upper insert part is inserted into a shock absorption tube. A thermal deformation prevention part is formed on the main body below the upper insert part and is recessed inward from the outer surface of the main body such that, when the main body is coupled to the guide thimble, a gap is defined between the thermal deformation prevention part and the guide thimble. The guide thimble and the shock absorption tube can be reliably fastened to the bottom nozzle, and thermal deformation of the guide thimble can be minimized.

Abstract: A hold-down spring unit for a top nozzle of a nuclear fuel assembly. The hold-down spring unit is coupled to the upper end of the top nozzle of the nuclear fuel assembly. The hold-down spring unit includes a first spring which provides a hold-down force upon the nuclear fuel assembly under start-up conditions or hot full power conditions of a nuclear reactor, and a second spring which provides an additional hold-down force upon the nuclear fuel assembly under start-up conditions of the nuclear reactor. The hold-down margin under start-up conditions or hot full power conditions is reduced, thus enhancing the mechanical and structural stability of the nuclear fuel assembly.

Abstract: A hold-down spring unit for a top nozzle of a nuclear fuel assembly. The hold-down spring unit is coupled to the upper end of the top nozzle of the nuclear fuel assembly. The hold-down spring unit includes a first spring which provides a hold-down force upon the nuclear fuel assembly under start-up conditions and hot full power conditions of a nuclear reactor, and a second spring which provides an additional hold-down force upon the nuclear fuel assembly under start-up conditions of the nuclear reactor. The hold-down margin under start-up conditions and hot full power conditions is reduced, thus enhancing the mechanical and structural stability of the nuclear fuel assembly.

Abstract: In an apparatus for producing U3O8 powder, the apparatus has an oxidation reactor including an interior space, a scrap box loaded with UO2 sintered pellets to be oxidized and introduced into the interior space of the oxidation reactor, an impact generating unit applying an impact to the scrap box to dissipate heat generated by the oxidation of the UO2 sintered pellets in the oxidation reactor, and a control unit controlling an oxidation process. The apparatus for producing U3O8 powder allows the heat generated by the oxidation of the UO2 sintered pellets in the oxidation reactor to be uniformly dissipated by the impact generating unit, thus producing U3O8 powder having a larger specific surface area which can be used to obtain a sintered UO2 pellet with a larger and more stable grain size of increased quality.

Abstract: A hold-down spring unit for a top nozzle of a nuclear fuel assembly. The hold-down spring unit is coupled to the upper end of the top nozzle of the nuclear fuel assembly. The hold-down spring unit includes a first spring which provides a hold-down force upon the nuclear fuel assembly under start-up conditions or hot full power conditions of a nuclear reactor, and a second spring which provides an additional hold-down force upon the nuclear fuel assembly under start-up conditions of the nuclear reactor. The hold-down margin under start-up conditions or hot full power conditions is reduced, thus enhancing the mechanical and structural stability of the nuclear fuel assembly.

Abstract: Disclosed is a spacer grid assembly with mixing vanes supporting fuel rods of nuclear fuel assemblies and mixing coolant that flows around the fuel rods, and more particularly, a spacer grid equipped with mixing vanes that mix coolant flowing around fuel rods. The spacer grid with hydraulically balanced mixing vane patterns, in the spacer grid equipped with a strip dividing a plurality of unit grid cells and a plurality of springs, protruded in uniform directions of vertical and horizontal directions on a grid surface of the strip and supporting nuclear fuel rods, which includes: a plurality of mixing vanes protruded to the downstream of coolant on an upper end of the inner grid surface, wherein positions and directions of the mixing vanes are formed in regular patterns on the spacer grid. Thus, it can minimize coolant flow induced vibration of the spacer grid by balancing hydraulic load generated by the mixing vanes, around the center of the spacer grids.

Abstract: A top nozzle is provided. The top nozzle can include a coupling plate, a perimeter wall and a hold-down spring unit. The coupling plate can be coupled to a guide thimble of the nuclear fuel assembly. The perimeter wall can protrude upwards from the perimeter of the coupling plate. A spring clamp can be provided on the upper surface of the perimeter wall. The hold-down spring unit can be mounted to the upper surface of the perimeter wall in such a way to couple a corresponding end of the hold-down spring unit to the spring clamp. A fastening pin hole can be vertically formed through an upper surface of the spring clamp. A spring insert hole into which the hold-down spring unit can be inserted and formed by electro-discharge machining in an insert direction of the hold-down spring.

Abstract: In an apparatus for producing U3O8 powder, the apparatus has an oxidation reactor including an interior space, a scrap box loaded with UO2 sintered pellets to be oxidized and introduced into the interior space of the oxidation reactor, an impact generating unit applying an impact to the scrap box to dissipate heat generated by the oxidation of the UO2 sintered pellets in the oxidation reactor, and a control unit controlling an oxidation process. The apparatus for producing U3O8 powder allows the heat generated by the oxidation of the UO2 sintered pellets in the oxidation reactor to be uniformly dissipated by the impact generating unit, thus producing U3O8 powder having a larger specific surface area which can be used to obtain a sintered UO2 pellet with a larger and more stable grain size of increased quality.

Abstract: A top nozzle for a nuclear fuel assembly and a method of manufacturing the top nozzle are provided. The top nozzle can include a coupling plate, a perimeter wall and a hold-down spring unit. The coupling plate can be coupled to a guide thimble of the nuclear fuel assembly. The perimeter wall can protrude upwards from the perimeter of the coupling plate. A spring clamp can be provided on the upper surface of the perimeter wall. The hold-down spring unit can be mounted to the upper surface of the perimeter wall in such a way to couple a corresponding end of the hold-down spring unit to the spring clamp. A fastening pin hole can be vertically formed through an upper surface of the spring clamp. A spring insert hole into which the hold-down spring unit can be inserted and formed by electro-discharge machining in an insert direction of the hold-down spring.

Abstract: A guide thimble plug for a nuclear fuel assembly is provided, in which an internal threaded hole is formed through a main body so that the main body is coupled to a bottom nozzle by a screw coupling. An upper insert part is formed in the upper end of the main body. The upper insert part is inserted into a shock absorption tube. A thermal deformation prevention part is formed on the main body below the upper insert part and is recessed inward from the outer surface of the main body such that, when the main body is coupled to the guide thimble, a gap is defined between the thermal deformation prevention part and the guide thimble. The guide thimble and the shock absorption tube can be reliably fastened to the bottom nozzle, and thermal deformation of the guide thimble can be minimized.

Abstract: Disclosed herein is a hold-down spring unit for a top nozzle of a nuclear fuel assembly. The hold-down spring unit is coupled to the upper end of the top nozzle of the nuclear fuel assembly. The hold-down spring unit includes a first spring which acts against a hold-down force with respect to the nuclear fuel assembly under start-up conditions or hot full power conditions of a nuclear reactor, and a second spring which acts against a hold-down force with respect to the nuclear fuel assembly under start-up conditions of the nuclear reactor. The present invention reduces the hold-down margin under start-up conditions or hot full power conditions, thus enhancing the mechanical and structural stability of the nuclear fuel assembly.