RICHLAND, Wash. - The EM Office of River Protection ’s (ORP) tank operations contractor recently deployed new tools that reduce radiological hazards to workers while removing pumps from nuclear waste storage tanks.
“The beauty of the tools is that they’re universal," said Mark Lindholm, Washington River Protection Solutions (WRPS) president and project manager. “We can pick and choose what tools we need to accommodate the next job."
Workers used the tools June 1 to remove a plugged waste transfer pump from double-shell tank AW-106, which contains about a million gallons of waste, resulting in increased protection for workers from radiation exposure. Removing the pump and draining its liquid contents allows for its shipment and disposal at the Environmental Restoration Disposal Facility, the Hanford Site ’s onsite landfill for low-level radioactive and mixed waste.
“The pump removal project is a shining example of how creative thinking and innovation can enhance worker safety while performing hazardous work," Lindholm said. “And with a multi-disciplinary team of 60-plus craft workers required to complete removal process, it also demonstrates the importance of good planning and teamwork."
Due to the presence of waste solids, gamma and beta radiation exposure risks were high for work on the 49-foot pump, weighing about 2,500 pounds. The innovative tools WRPS developed and successfully deployed included:
* A custom hydraulic punch assembly to drain the pump. It features jaws that closed around the pump’s 5-inch steel pipe column and made penetrations along the column while the pump was raised out of the tank riser and into the pump pit. This allowed the waste to drain from the column and back into the tank.
* A remotely installed spray ring system, eliminating the need for workers to enter a hazardous tank pit. Spray rings are used to clean the external surfaces of pumps during removal.
* Tension brackets attached to the top hat (a device used to deploy sleeving that sits atop the work platform) allowed workers to apply pressure, preventing the plastic sleeving from drawing back into the pit because of the tank’s negative pressure. Previously, workers often had to manually hold back the sleeving to keep it from drawing back into the pit.
* An encapsulation device to spool 2-inch-thick foam insulation wrapped around the pump column as it was raised from the pit. Workers secured the foam with heavy-duty zip tie-like fasteners. This eliminated the need for workers to make contact with the pump column during removal, where dose rates are the highest.
“This is a great example of safety culture and the integrated safety management system working together," said Glyn Trenchard, acting ORP assistant manager for the tank farms project. “I commend WRPS’s management and employees for the way they collaborate and implement enhancements that result in increased safety and operational efficiencies in the tank farms."
Other tools used during the pump pull included a modular work platform with pass-through plates where hoses and other hydraulic connections can be accessed, aluminum top hat covers to provide additional shielding, and a place for workers to set their tools.
The tools will be used this summer to remove another plugged pump, AP-106, and other long-length pieces of equipment.
WRPS is responsible for managing 56 million gallons of radioactive and chemical waste stored in 177 underground tanks and preparing the waste for delivery to the Waste Treatment and Immobilization Plant.
Source: U.S. Dept. of Energy, Office of Environmental Management
