Nuclear Fuel Canister Welding Solutions

The Moog Automated Welding System (AWS) performs semi-automatic Gas Tungsten Arc Welding (GTAW) to seal canisters containing spent nuclear fuel. Operator specified and supervised welding is performed in accordance with Nuclear Regulatory Commission regulations including compliance with the ASME Boiler and Pressure Vessel Code Sections lll and 1X as well as AWS D1.1. The AWS also includes the capability to remove the canister’s lid using an interchangeable plasma torch.

Reduced Worker Radiation Exposure

AWS reduces welding operator time near the spent fuel canister, as well as the number of required operators. Operator distance from the canister is increased as well, minimizing rework, and eliminating tool failures.

• AWS only needs to be approximately centered on the canister lid by a remotely operated crane
• High-levels of welding process automation enable a team of two operators to be as productive as teams of four with prior generation automated welding systems
• Welding set-up, and welding itself, is performed by operators located at a machine control console up to 100 feet from the canister
• Need for weld rework is minimized by the excellent process control provided by operator supervised automated welding
• Robust control system design supports remote recovery from faults or stops, and reduces causes of system failure

Precise Semi-Automated Welding of Complex Geometries

Continuous, real-time, five-axis control of the torch head position enables precision welding of canister lids, as well as keyways or penetrations.

• AWS theta-axis rotation allows the weld-arm to travel around the rim of the six feet in diameter canister lid
• Radial arm adjusts the radial distance to the torch tip from the AWS center axis
• Height-axis raises and lowers the torch tip to follow the workpiece and maintain a constant welding voltage
• Twist-axis “twists” the torch tip to keep it perpendicular to the seam
• Torch tilt-axis enables the torch tip to reach points at the proper angle along the seam to prevent interference with canister wall
• A sixth servo-controlled axis controls welding wirefeed
• All six axes are precisely coordinated in real-time by the AWS control system

Operator and Automation Work Together

The welding system guides the remote operator through a pre-programmed canister welding process proven to produce good welds by prior customer use. The operator supervises, and may fine-tune, the process on-the-fly to achieve the desired weld.

• An AWS control algorithm (with remote operator assistance) quickly learns the precise location of the weld to be performed, accommodating the casual physical centering of the welder on the canister, which substantially reduces worker radiation exposure as it is done with a crane
• AWS provides pre-programmed welding operations including inner cover, outer cover and qualification welds, tack welds, root welds and circumference welds
• Necessary weld geometry and default welding recipes are sourced with the welder facilitating end-user’s welding experts program exact welding process parameters based on their experience and preference.
• Canister welding is subsequently, and repeatedly, executed utilizing pre-programmed weld geometry and process parameters-parameters proven by prior customer use
• Precise control and synchronization of welder axes and weld process parameters are delivered by the welder’s integrated, real-time control system
• Remote, two camera, video monitoring of the leading and trailing edge of the weld puddle, tungsten tip, wire entering the puddle, and weld prep
• On-the-fly fine-tuning allows the supervising operator to accommodate for deviations, such as canister or lid dimensional variations and deformation due to heat input during welding and achieve the desired weld