Underwater robot maps water storage tank

19th May 2017

Lanna Deamer

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Newton Labs and AREVA NP successfully completed a robotic examination of a filled CST (Condensate Storage Tank) using Phased Array UT and VT-1 Visual Examination at a US nuclear facility in April. The exam satisfied requirements for license renewal and the NEI 09-14 directive on buried pipes and tanks.

AREVA NP engineers conducted the survey of the tank floor by using a combination of phased array ultra sound and visual examinations utilising the Inspector underwater robot, designed, manufactured and operated by engineers from Newton Labs. Traditional storage tank inspection methods require the tank to be drained and ventilated so that humans in protective clothing can enter and conduct the exam. With the use of the Inspector robot, it is not necessary to drain the tank or stop water circulation. In fact, tank inspections with the Inspector robot have been performed off outage without any obstruction to plant operation.

The Inspector robot provided all data requested by site engineering in order to satisfy their license renewal and NEI 09-14 requirements. The robot surveyed over 90% of the tank bottom by inspecting each of the 36 floor plates of the 54ft (16.5m) diameter tank, as well as visually examining the perimeter welds where the 52ft (15.8m) tall tank wall meets the floor.

“We’re proud the Inspector has provided another cost-saving examination,” said John Bramblet, Newton Labs’ President. “Comparing multiple exam results will allow for trending analysis and the enhanced visual capabilities met VT-1 requirements for license renewal.”

Newton and AREVA NP partnered in January to offer this innovative solution with enhanced NDE techniques and coverage. The Inspector robot was first deployed at Palo Verde Nuclear Generating Station in the fall of 2014 and has had many successful deployments since.

The Inspector underwater robot is equipped to carry two NDE probes in addition to five on-board video cameras which provide 360° plus down-looking live video. A built-in down-pointed laser scanner with 0.01" (0.3mm) resolution outputs a detailed point cloud that, when applied to 3D software, a fully measurable CAD model can be generated. The robot’s precision navigation system enables the locations of defects found on any plate to be mapped, allowing the robot to later return to those locations with +/- 1/8" (0.3mm) accuracy.