ARC SAW TECHNOLOGIES, LLC | ADVERTORIAL FEATURE
Overall Arc Saw Performance The Arc Saw cutting mechanism performed exactly as designed and tested and in fact whereas AST had provided six spare blades for the project, at G-2 they used a total of 2 blades for all cutting. The one problem area was the Ground Clamp design which required adjustments in Montreal as described in the Lessons Learned. The Feed mechanism ultimately performed successfully, but improvements became obvious as work progressed. The aluminium feed tray suffered from corrosion from the deionized water of the pool causing disruptions in the smooth pathway to the cutting position. While the system was not designed to last for more than a year or so, it did survive sufficiently to perform its intended function. The Lessons Learned and recommended improvements from the field operations are described herein.
Lesson 1: Precision in Cutting The Shield Plug advance often stopped at the pivot of the stop gate instead of at the gate. The pivot should be relocated externally from the exit tray to avoid interference. The Shield Plugs tended to dig in the aluminium ramp guides to the Ground Clamp. The guides should be replaced with stainless steel.
Lesson 2: Operational Accessibility The replacement of the original laid-on tank cover with a hinged cover greatly facilitated operations within the tank. The laid-on cover tended to float and lose its seal when the saw blade was operating.
Lesson 3: Sawing Rotation The lighter-weight unclamped-side of the Whole Adjuster Rods lifted up towards the last second of cutting because of the Arc Saw’s upward rotational direction. A simple pivot restraint system in front of the arc saw could prevent inadvertent movements. An aluminium angle with a pivot and a lock would suffice. Reversing the blade rotation would be a solution.
Lesson 4: Blade Side Arcing Blade side-arcing normally occurs, and the simple solution was to provide extra blades. AST provided six blades, but G-2 only used two. Ceramic coating the blade is recommended. Eliminating the side arcing forces the arc to the saw periphery and increases saw efficiency.
Lesson 5: Combatting Corrosion As operational components aged, difficulties arose in the movement of pivotal and rotating elements due to corrosion, cutting dross and debris. Aluminium was selected for most of the components for its ease of machining. The recommendation is to install press-fit stainless bushings for smoother operations.
Lesson 6: Feed Tray Design The Feed Tray was attached to the Tank by a V-Groove design. The Tray lifted during advancement. Removing one leg and placing the remaining leg of the tray towards its back end would solve this issue.
Lesson 7: Filtration Enhancement Blade rotation was selected upward directing the dross into the filter system intake funnel. Reversing the rotation of the blade downward and repositioning the pump’s suction under the machine will increase the filtering efficiency.
Lesson 8: Hydraulic System Optimization The addition of a check valve on the hydraulic line of the saw motor would prevent oil return in the pump during stops, which caused a “water hammer” effect.
Lesson 9: Technological Upgrades The original aluminium blade change tool was not sufficiently rigid. G-2 revised the design slightly and changed the material to stainless steel. The original stepper drive motor was air-pressured to
prevent in-leakage of contaminated water. Although the stepper motor performed as designed, consider replacing the stepper motor with a hydraulic motor to reduce the risk of stepper motor failure.
Lesson 10: Ground Clamp Reliability The ground clamp design used two air-operated cylinders under the clamp to actuate it. An improved design would relocate the cylinders to the top and with improved rod seals to eliminate grit/rod interaction. and possibly using hydraulic cylinders with higher pressure. The clamp was designed for two different diameters of Plugs and Bars. However, some had different diameters due to storage corrosion accumulation leading to clamping problems.
Conclusion This first-of-its-kind Arc Saw performed exactly as designed. Blade life was better than expected. The Feed system although ultimately successful, created problems that had to be corrected in the field. Fortunately, the AST, CCNuclear and G-2 personnel were experienced to dealing with these issues and successfully completed the intermediate level waste segmentation project of the bays at G-2, which is a prerequisite for final decommissioning of the bays. ■
Contact: Mr. LaGuardia at (203) 300-2958 or Mr. Simoneau at (203) 833-3902
www.neimagazine.com | February 2024 | 23
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