U.S. Department of Energy

Pacific Northwest National Laboratory

New Microscope Reveals Xenon in Fuel Cladding

Identification of the chemical element delivers new knowledge and demonstrates benefit from application of an advanced microscopy capability

The revelation, the first observation of its kind, will provide insights into how Xenon got into the cladding and chemically fractionated during nuclear reactor operations. Such information could lead to advances in future fuel designs.

To obtain the result, researchers introduced the radioactive fuel sample into the GrandARM scanning transmission electron microscope, installed at RPL just this year and one of only three such instruments in the U.S. The microscope uses a 300-kiloelectron volt beam, which enables the exploration of thicker regions of a specimen. The instrument's probe aberration correction helps maintain excellent spatial resolution, and the dual energy-dispersive detectors, unique to the GrandARM, allow rapid detection of xenon and other minor species.  

Xenon is the most common fission product generated in spent nuclear fuel. The first observations of the element were made in uranium dioxide fuels. Attempts to locate xenon in cladding failed previously because instruments with lower-energy beams could not penetrate the regions of the sample where the gas was intact.

The GrandARM resides in RPL's new Quiet Suite for high-end microscopy, and is one of four microscopes expected to revolutionize PNNL's micro-analytical characterization capabilities for studying radiological materials.

The RPL is a Hazard Category II Non-Reactor Nuclear Facility. Along with other PNNL assets, the laboratory provides key state-of-the-art nuclear research resources of value to the nation.

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