RICHLAND, Wash. - EM’s Office of River Protection (ORP) and tank farms contractor Washington River Protection Solutions (WRPS) are starting to get to the bottom of things when it comes to learning more about Hanford ’s double-shell liquid waste tanks.
For the first time, they recently deployed two visual inspection platforms through the refractory air slots of tank AP-107. Both platforms - one designed and constructed by WRPS subcontractors Veolia and Inuktun, and the other by WRPS subcontractor Adaptive Energy - navigated the full radius of the refractory to the center of the primary tank, a distance of more than 35 feet. The refractory, which sits between the primary tank and secondary liner, has a pattern of 2½-inch slots for cooling of the primary tank. All of Hanford’s double-shell tanks are 75 feet in diameter with a capacity of at least one million gallons.
“ORP and WRPS are thrilled with the results," said Jeremy Johnson, ORP deputy federal project director for tank farms. “The inspections revealed that the tank bottom and refractory pad appear to be in excellent condition with no signs of significant degradation."
Deployment of two crawler systems in the refractory of AP-107 was the culmination of years of research and collaboration with experts in robotics and nondestructive examination, as well as the testing of different tools and technologies.
At left is the inspection system designed and constructed by Washington River Protection Solutions subcontractor Adaptive Energy.
Below right is the inspection system designed and constructed by Washington River Protection Solutions subcontractors Veolia and Inuktun.
For several years, ORP has been committed to gaining a better understanding of existing and emerging tank integrity issues. One of the greatest needs has been to find a technology to visually inspect the bottom of primary tanks. The deployment of the two crawler systems was the culmination of extensive research, collaborating with experts in robotics and nondestructive examination and testing different tools and technologies.
“It’s extremely rewarding for so many people associated with the effort," said Jason Gunter, a WRPS engineer. “Developing and implementing the tools to visually inspect the underbelly of primary tanks will help us achieve our ultimate goal to support extended service lives of the double-shell tanks."
Both inspection systems feature “marsupial" crawlers, similar to a mother robot carrying and releasing smaller robotic inspection devices. The larger crawler enters the carbon steel tank through a riser, clings to the primary tank wall with magnets, travels along the sidewall, and launches the smaller inspection tools into the air slots.
One of the crawlers lines up with air slot entrances at the base of the primary tank to send a micro-crawler into the refractory pad. The micro-crawler carries two visual inspection cameras at the front and rear with integrated lighting and temperature and radiation sensors.
The other inspection system is carried by Hanford’s existing ultrasonic testing crawler fleet used for regular tank inspections. The system features a new cable push-and-pull attachment that guides and pushes a camera via its rigid tether through the air slots.
While deployment of these technologies is a positive first step, it is only the start of much more work to come, Johnson said.
“We’re pleased that both crawler systems were highly successful and we’re eager to advance these platforms and develop additional sensors that will help us learn more about the condition of the tank bottoms, much like we currently do for the tank walls," he said.
Source: U.S. Dept. of Energy, Office of Environmental Management
