Prathamesh Bilgunde, a graduate student majoring in Engineering Mechanics, received the Robert Uhrig Graduate Scholarship Award from the American Nuclear Society for his work on high temperature transducers in nuclear reactors. The scholarship, which awards students pursuing graduate research with a focus in the field of nuclear instrumentation and controls, is named after Robert Uhrig, a former Iowa State professor in the 1960’s. During his time at Iowa State, Uhrig worked in the building adjacent to where Bilgunde has been doing his research.
Bilgunde’s graduate research is funded under the Nuclear Energy University Program (NEUP) by the Department of Energy. It is a continuation of the work done by his professor, Leonard Bond, while he was at the Pacific Northwest National Laboratory in Richland, Washington.
“This transducer technology is a key to enable safe and economic operation of a liquid metal cooled reactor, and is used for under-coolant viewing and in-situ non-destructive inspection of critical components,” Bilgunde said.
Bilgunde’s goal is to understand why previous designs did not give desired performance and demonstrate a novel methodology that could significantly improve the transducer sensitivity to provide better images of the reactor under the silvery liquid metal while it continues to operate.
“If you don’t have an ultra-sonic viewing system, you’re basically flying blind inside the liquid sodium, it’s optically opaque,” Bond says. “Say you want to move fuel rods around then you would like to be able to monitor or inspect the inside of the reactor for cracks or broken parts.”
The transducers that Bilgunde is working with are not the ultrasound scanning probes that you would normally see in a medical ultrasound machine. The ultrasonic scanning capabilities needed for nuclear reactors must operate with an optimum signal to noise ratio at temperatures up to 260 degrees centigrade for eight hours, and still continue work at the end of the day.
“His task was to go beyond something that just survives, to give something that works better,” Bond said. “You can develop good phased array transducers which operate at room temperature, that part is well understood. High temperature transducers are a lot more challenging and complicated.”
The United States does not currently have a working sodium-cooled fast reactor and a working transducer is imperative for this technology to exist. China, Japan, and India are currently the only countries that have operational sodium-cooled fast reactors. Bilgunde wants to ensure that if a sodium reactor does come to the U.S., the transducer is capable of handling the rigorous workload and temperatures.
“The objective of my graduate research is to quantify each factor that causes the degradation of the transducer sensitivity at an elevated temperature.” Bilgunde said. “Using a physics based modeling approach, we have been able to quantify the causality between thermal degradation of the piezoelectric material and ultrasonic transduction. This has helped in selecting a new high temperature piezo-electric material which can give the required sensitivity at 260 degrees centigrade.
As the first Iowa State student to win this award, Bilgunde sees it as a motivator to continue his research.
“It is a nice recognition as well as an encouragement to continue the fundamental work in developing robust transducers for harsh environment” Bilgunde said.
His professor meanwhile, sees it as recognition that they are on to something big.
“In terms of sodium fast reactor instrumentation, this project is absolutely on the cutting edge,” Bond says. “It’s the leading work in the U.S., and he’s had his head down and worked really hard.”