Abstract: Debris filters fit in fuel assembly lower tie plates and filter fluids passing therethrough. Filters use a series of adjacent plates with aligned peaks and valleys to create several channels. The plates have small excisions in diamond, triangle, or other debris-catching shapes, such as near a lower portion of the filter where fluid enters the filter. Excisions may alternate around each channel, such as four alternating cut-outs in 90-degree intervals about a channel circumference. Excisions may be sized to entrap smaller debris common in reactor coolant flow and liable for fretting damage to fuel cladding. Multiple vertical stages can be used in filters, with different channels for each stage. Ligaments may hold each stage to the next, potentially with a gap between stages for intermixing. Plates, peaks, valleys, ligaments, and excisions may all be formed in a single stamping operation to eliminate excess or overlapping pieces or extensions.

Abstract: Debris filters fit in fuel assembly lower tie plates and filter fluids passing therethrough. Filters use a series of adjacent plates with aligned peaks and valleys to create several channels. The plates have small excisions in diamond, triangle, or other debris-catching shapes, such as near a lower portion of the filter where fluid enters the filter. Excisions may alternate around each channel, such as four alternating cut-outs in 90-degree intervals about a channel circumference. Excisions may be sized to entrap smaller debris common in reactor coolant flow and liable for fretting damage to fuel cladding. Multiple vertical stages can be used in filters, with different channels for each stage. Ligaments may hold each stage to the next, potentially with a gap between stages for intermixing. Plates, peaks, valleys, ligaments, and excisions may all be formed in a single stamping operation to eliminate excess or overlapping pieces or extensions.

Abstract: Debris filters fit in fuel assembly lower tie plates and filter fluids passing therethrough. Filters use a series of adjacent plates with aligned peaks and valleys to create several channels. The plates have small excisions in diamond, triangle, or other debris-catching shapes, such as near a lower portion of the filter where fluid enters the filter. Excisions may alternate around each channel, such as four alternating cut-outs in 90-degree intervals about a channel circumference. Excisions may be sized to entrap smaller debris common in reactor coolant flow and liable for fretting damage to fuel cladding. Multiple vertical stages can be used in filters, with different channels for each stage. Ligaments may hold each stage to the next, potentially with a gap between stages for intermixing. Plates, peaks, valleys, ligaments, and excisions may all be formed in a single stamping operation to eliminate excess or overlapping pieces or extensions.

Abstract: A debris exclusion and retention device traps and retains foreign material within the lower tie plate of the fuel assembly utilizing the existing flow paths within the lower tie plate, and without redirecting coolant flow. Flow through the inlet nozzle of the lower tie plate into an enlarged lower tie plate housing creates strong jet impingement against the center of the lower tie plate grid or debris filter, if present, which has a tendency to push debris to the periphery of the lower tie plate. Low flow zones around the periphery of the lower tie plate allow debris to fall back toward the inlet nozzle. The retention device traps and retains debris in these low flow zones without impacting existing flow patterns in the lower tie plate. Thus, the retention device has minimal or no impact on lower tie plate pressure drop.

Abstract: A debris exclusion and retention device traps and retains foreign material within the lower tie plate of the fuel assembly utilizing the existing flow paths within the lower tie plate, and without redirecting coolant flow. Flow through the inlet nozzle of the lower tie plate into an enlarged lower tie plate housing creates strong jet impingement against the center of the lower tie plate grid or debris filter, if present, which has a tendency to push debris to the periphery of the lower tie plate. Low flow zones around the periphery of the lower tie plate allow debris to fall back toward the inlet nozzle. The retention device traps and retains debris in these low flow zones without impacting existing flow patterns in the lower tie plate. Thus, the retention device has minimal or no impact on lower tie plate pressure drop.

Abstract: A process of using laser welding in the assembly of boiling water reactor fuel debris filters is disclosed. The laser welding process minimizes the distortion of the debris filter cast lower tie plate by applying minimal heat during the welding. Fixtures hold the cast lower tie plate through four degrees of motion under a constant controlled laser source during welding. The welding process also reduces the potential for stress corrosion cracking resulting from crevices in partial penetration welds that might occur in a laser welding process.