Understanding next-generation nuclear fuel

nearly forty years, researchers have studied silver in the particles without finding a satisfactory explanation for its movement during and after irradiation.

The release notes that this achievement was possible due to critical capabilities at INL to prepare very small irradiated specimens using the focused ion beam (FIB) at the Materials and Fuels Complex, the STEM at CAES, and the team’s supportive and innovative research approach. Only earlier this year, modifications to the CAES licensing agreement were approved by the Nuclear Regulatory Commission (NRC), allowing very small specimens with a low radiation dose to be examined at CAES, which was previously impossible. CAES is a research and education partnership between INL, Boise State University, Idaho State University, and University of Idaho.

Now that the silver has been found, “the real fun begins,” Van Rooyen explains. It has been her dream to work on irradiated TRISO fuel and she says this discovery “opens the door for many future applications of TRISO fuel for both very high temperature reactors and small modular reactors.” Van Rooyen started the search for silver and the relevant transport mechanism in 2006 on nonirradiated fuel while working on pebble bed modular reactors in South Africa. That research brought her to INL in 2011, and she is pleased that in two short years the research is paying off.

Yaqiao Wu, a Boise State University research associate professor and instrument lead of Materials and Characterization Suite at CAES, echoes her excitement. “The expertise of the staff, researchers and the equipment at CAES played critical roles in making this discovery possible,” he said. “The smallest electron beam size with the STEM is around 1 nanometer, which is crucial for revealing the nanosized silver-rich phase in this particle.”

Fellow INL researcher Tom Lillo agreed, saying, “We are very fortunate to have state-of-the-art equipment and facilities to look at things that are happening on an extremely small scale in order to understand the behavior in large, advanced energy systems.”

The next step for the team is to continue to test and study the results. Team members say that more research is needed to identify the silver transport mechanism and to continue monitoring how the silver behaves.

For more information on the research, see the conference proceedings here.INL is one of the DOE’s 10 multiprogram national laboratories. The laboratory performs work in each of the strategic goal areas of DOE: energy, national security, science and environment. INL is the nation’s leading center for nuclear energy research and development. Day-to-day management and operation of the laboratory is the responsibility of Battelle Energy Alliance.