West Valley Nuclear Services processes and packages obsolete nuclear process equipment and materials. Their contractors, Butler Construction, Quackenbush Co, and West Metal Works, were challenged with building a remote handling system that could transport unprocessed nuclear waste down a long corridor and through a series of steel shield doors. Once in the inner chamber, processing would begin and the resulting material packaged for safe disposal.
The engineers came to Joyce/Dayton with two challenges:
- Provide a transfer system that could move a specific load a horizontal distance of 80 ft in 20 ft increments.
- Customize the jack and power system to meet the unique design challenges of the nuclear industry.
The equipment would have to be modified to allow a smooth transfer across the thresholds of the steel doors without compromising the shielding''s integrity. The equipment could not be prone to leaking fluids, which pose cleanup and maintenance problems in the nuclear environment. And the equipment would have to be rugged, reliable, and capable of functioning throughout the 20 year life of the project.
Unique features of the system include:
- Encoder system
- Split nut for remote placement
- Recovery system with hex nut drive extension
- Variable frequency drive for overcurrent protection (safety against self-destruction)
How The System Works
A series of 25-ton Joyce® ComDRIVE® systems transport the load over a horizontal distance of about 80 ft. The special rotating screw design allows the traveling nut to pass over a central support bushing in the screw with uninterrupted travel.
As the ComDRIVE powers the transfer system, nuclear waste is conveyed down an 80 ft long corridor. As the load traverses the corridor, it is transferred across thresholds onto successive ComDRIVE systems until it has completed the full distance. Stainless steel doors close as it passes each threshold, sealing the nuclear waste in an inner chamber.
Joyce/Dayton engineers worked with project engineers to provide the needed modifications to the 25-ton ComDRIVES. They include custom-designed screws, jack sleeves, traveling nuts, and added features on the gear reducers. The end result was a successful transfer system whose function is central to the success of the waste packaging process.
Why jacks? The following characteristics explain the choice:
- Reliable
- Proven ComDRIVE design.
- Screw Jack technology is not prone to the same failures as hydraulic systems.
- Screw jacks are mechanically able to move large loads over long distances (field tested to 75,000 lbs.).
- They can be modified for remote repair and replacement.
- Adaptable to customer''s unique design concept.
- Material options are available to meet nuclear requirements.
- Cost-effective solution.
- Engineering support available.