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Experimental Sensors for Nuclear Safety Show Promise

Jamie Coble

In 2011, when Japan experienced a massive tsunami and subsequent meltdown at the Fukushima Daiichi nuclear plant, renewed attention to nuclear safety swept the globe. There are more than 450 nuclear reactors on the planet – many of them built more than 40 years ago, before the discovery of some of the potential environmental dangers that are known today. Many of Japan’s nuclear reactors, for example, were built in the 1970’s and are perched on the coast.

With an increased focus on nuclear safety, research has turned toward the development of accident tolerant nuclear fuels. Testing these fuels, however, is difficult. Current methods put a fuel into a test reactor, irradiate it for a period of time, take it out, and evaluate it, providing a limited amount of data exclusively from the end points of the experiment.

Jamie Coble, associate professor of nuclear engineering and Southern Company Faculty Fellow, hopes to change this. Her JDRD work is currently focused on building a sensor to collect data on nuclear fuels while they are in the reactor, providing a much clearer picture of what is happening in the experiment.

“This is very challenging to do for a number of reasons. It’s a high-radiation, high-temperature environment. It’s also very tight, so there’s not a lot of space to put in a big, bulky sensor,” said Coble.

To address these limitation, Coble’s team worked to develop a sensor that was capable of surviving the extreme conditions inside the reactor and small enough to fit inside the available space. The completed sensor fits around a fuel rod like a ring or cuff and measures any dimensional changes taking place as a result of the irradiation.

In the first year of Coble’s JDRD work, her team identified appropriate materials from which to construct the device, conducted modeling and simulation, and designed and built both the sensor and a testing apparatus to conduct initial experiments.

“Our initial results look really good. We’re getting different enough measurements that we can actually differentiate some changes in the material,” said Coble. “In the first year I feel like we got pretty good agreement between our simulations and our experimental results.”

Coble plans to take her sensor to ORNL for testing with collaborators there, which may require some alterations to accommodate a different experimental system. She hopes to present the team’s progress at a meeting of the American Nuclear Society.