The invention relates to a fuel assembly for a boiling water reactor which is adapted, during operation of the reactor, to allow water to flow upwards through the fuel assembly while absorbing heat from a plurality of fuel rods, whereby part of the water is transformed into steam The fuel assembly comprises a steam channel through which the steam flows through the fuel assembly The steam channel (16a, 16b, 16c, 16d) consists of an empty volume which at least extends through part of the fuel assembly The fuel assembly is designed such that the water and the steam are brought to rotate around the steam channel whereby the water is thrown away from the steam channel whereas the steam which is separated from the water flows upwards through the steam channel

Nuclear fuel assembly

A computer controlled apparatus is disclosed for performing a series of laser machining operations on a work piece in an environment comprised of a non-reactive gas with respect to the material of which the work piece is made. The computer controlled apparatus includes a machining chamber for receiving the work piece and means in the form of a pump for directing the non-reactive gas into the machining chamber at a controlled, selected rate. A laser beam is generated by a laser and is focused into a beam along a path to the work piece. An assembly is provided for selectively moving the machining chamber and its work piece therein through a sequence of steps, whereby the relative position between the work piece and the laser beam is changed such that a series of lasing operations and, in particular, welds may be effected on a sequence of selected sites of the work piece. A computer is programmed to control the rate at which the non-reactive gas is introduced into the machining chamber, as well as to the machining sites of the work piece, whereby the selectively moving assembly may be controlled to dispose the work piece to effect the series of welding operations.

Laser machining system

An improved bottom nozzle of a fuel assembly includes a housing and a modified adapter plate formed by a network of ligaments which extend across the housing and are connected to the side walls of the housing a short distance below its upper peripheral edge so as to define an open region therein. The improved bottom nozzle also includes a debris trap having a structure disposed within the open region of the housing upon the adapter plate and adapted to capture and retain debris carried by collant flowing from openings in the lower core plate of the nuclear reactor to the fuel assembly. The trap structure is composed of a plurality of straps aligned with one another in a crisscross arrangement and defining a plurality of interconnected wall portions which form a multiplicity of small cells each having open opposite ends and a central channel for collant flow through the trap. A plurality of spring-like fingers are punched out of the wall portions and bent to extend into the cell channels toward the downstream end of the trap structure to provide means to capture and retain pieces of debris carried through the channels by flowing coolant. Also, leaf springs are attached to periphery of the structure and engagable with a plurality of recessed shoulders in the housing for releasably locking the trap structure in place in the open region with intersections formed by the straps aligned below the fuel rods of the fuel assembly.

Fuel assembly bottom nozzle with integral debris trap

A fuel assembly for a nuclear reactor comprises a 5 x 5 array of guide tubes (56) in a generally 20 x 20 array of fuel elements (48), the guide tubes (56) being arranged to accommodate either control rods or water displacer rods. The fuel assembly has top and bottom Inconel grids (58, 60) and intermediate Zircaloy grids (62) in engagement with the guide tubes (56) and supporting the fuel elements (48) and guide tubes (56) while allowing flow of reactor coolant through the assembly.

Fuel assembly for a nuclear reactor

The spent fuel consolidation system provides a system for vertically and remotely dismantling an irradiated nuclear fuel assembly while the fuel assembly remains submerged in a coolant and for consolidating the spent fuel rods of the dismantled fuel assembly. The system comprises a platform rotatably mounted on a vertical support with a fuel assembly station, a consolidation station, and a canister station attached to the platform. A gripper mechanism is slidably disposed on the vertical support for transferring spent fuel rods from one station to another as the various stations are rotated into alignment with the gripper mechanism. The fuel assembly station provides a station for holding the fuel assembly while the spent fuel rods are removed therefrom, the consolidation station provides a station for consolidating the spent fuel rods, and the canister station provides a station for holding the consolidated spent fuel rods.

Spent fuel consolidation system

The basic fuel assembly structure for a nuclear reactor comprises a skeleton made up of individual hollow tubes composed of a zirconium base alloy, such as Zircaloy, and held in place by Inconel or stainless steel grids disposed between stainless steel end nozzles at the top and the bottom of the structure. The tubes serve as guide thimbles for cylindrical control elements strategically located in a square array of fuel rods held in place by spring fingers on the "egg-crate" grids. The guide thimbles are attached to the top and bottom nozzles and the grids by mechanical joints without welding dissimilar metals.

E Choby

Papers

Low parasitic capture fuel assembly structure