Have trouble getting to those hard-to-reach places? We all do – especially some of our utility customers! But to comply with the Nuclear Energy Institute (NEI) Guideline for the Management of Underground Piping and Tank Integrity (NEI 09-14), they need to periodically assess and manage the condition of certain types of buried pipes as well as water storage tanks, both above and below ground.
During their spring 2017 outage, one such customer – APS’s Palo Verde Nuclear Generating Station in Arizona – requested AREVA NP’s assistance to perform non-destructive examinations (NDE) in one of their above ground water storage tanks to satisfy the NEI 09-14 directive and to meet requirements for license renewal. 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.
So the challenge became: how do we get in there to not only examine the tanks for pitting and crevice corrosion but also identify the issues and record the material thickness of the tank bottom – without putting people in the tank?
Partnering with Newton Labs, AREVA NP’s NDE team came up with an innovative solution involving Newton’s Inspector in-tank robot – a semi-autonomous underwater platform that can deploy a variety of advanced NDE sensors to over 90% of a flat-bottom water storage tank (the type used at nuclear power plants) and map the position of any indications – including those hard-to-reach places near the wall’s edge – with accuracy of one-eighth of an inch (3mm). Using an AREVA probe and enhanced inspection technique developed by AREVA NP’s NDE experts, the team performed underwater ultrasonic testing (UT) and visual testing (VT-1) on the tank floor. And the approach didn’t require the plant to drain the tank or remove it from service!
This first deployment of this new tank inspection solution was a resounding success! Previously the plant operator could count on getting one single thickness reading – the minimum. That’s it. The dynamic duo of AREVA NP and Newton’s Inspector was able to acquire the data, synchronize and export it, then import it into Excel – giving the customer over 2 million data points on the thickness of the plate – all in an easy-to-use package.
AREVA NP and Newton Labs are proud to do their part to ensure the continued safe operation of the Palo Verde plant.
- Read about AREVA’s partnership with Newton labs HERE.
- Read about the navigation process of the Inspector HERE.
- Read about the sensor and tool-attachment capabilities of the Inspector HERE.
Newton Labs’ Inspector in-tank robot
Pitting due to corrosion in a steel plate surface like that found in the above ground water storage tank
Ultrasonic testing imagery of the previous pitted steel plate surface
Ultrasonic testing imagery of the previous pitted steel plate surface
Ultrasonic testing data of the previous pitted steel plate surface
