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Surrogate Material Studied for Nuclear Reactor Operations

Radiation effects research featured on cover of Journal of Materials Research

June 2015
 Surrogate Material Studied for Nuclear Reactor Operations
The cover of Journal of Materials Research, featuring an illustration of the high density of defects from molecular dynamic simulations at the atomic level.
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Understanding the behavior of fuels and cladding materials during the operation of nuclear reactors is crucial to improving the economics and safety of nuclear power. But studying irradiated uranium dioxide, or urania, is extremely challenging and hazardous. Due to these barriers, there is an increasing interest in using a surrogate, called ceria, to complement post-irradiation examination of nuclear fuel. However, the differences between the chemistry of these two materials and the limited comparative data are a cause for concern to some scientists.

A team of researchers from national laboratories, industry, and one university gathered the data needed to address the concerns with using ceria in place of urania, while also aiming to better understand the fundamental science of radiation effects in materials. As published in the Journal of Materials Research and featured on the cover, the research demonstrated that ceria retains it crystal structure under the onslaught of swift heavy ions, but there is a decrease in density along the ion track, the damage-trail, due to the accumulation of vacancy clusters. The simulation results shed light on the initial stages of the production of defects—called interstitial loops—seen in experiments.

Simulations with a Surrogate

As swift heavy ions produced by nuclear fission slow down by transferring energy to the cladding material, fuel is damaged at the atomic-level. This negatively impacts the thermal conductivity, fuel pellet integrity, and fission product retention.

The research team irradiated crystals of ceria with gold ions accelerated to very high energies to understand fission fragment damage in nuclear fuel. In addition to performing high-resolution electron microscopy and spectroscopy of the irradiated material, the researchers used high performance computing to fill gaps in the experimental data. This integration of experiment and computer simulation is essential, because the fundamental processes governing radiation damage take place on small time and distance scales that are not easily replicated in experiments.

The team hopes to continue this work to understand the degradation of fuel and cladding under extreme operating conditions. For more information, contact Ram Devanathan.

Yablinsky, C. A., Devanathan, R., Pakarinen, J., Gan, J., Severin, D., Trautmann, C., & Allen, T. R. (2015). Characterization of swift heavy ion irradiation damage in ceria. Journal of Materials Research, 30(09), 1473-1484. DOI:

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