Publications by authors named "D L Willingham"

Microscopic fuel fragments, so-called "hot particles", were released during the 1986 accident at the Chornobyl nuclear powerplant and continue to contaminate the exclusion zone in northern Ukraine. Isotopic analysis can provide vital information about sample origin, history and contamination of the environment, though it has been underutilized due to the destructive nature of most mass spectrometric techniques, and inability to remove isobaric interference. Recent developments have diversified the range of elements that can be investigated through resonance ionization mass spectrometry (RIMS), notably in the fission products.

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We present a description of the capabilities and performance of the NAval Ultra-Trace Isotope Laboratory's Universal Spectrometer (NAUTILUS) at the U.S. Naval Research Laboratory.

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Precise and accurate measurement of U and Pu isotopes from micrometer-sized particles represents new verification challenges for the International Atomic Energy Agency. The U and Pu isotopes and U-Pu elemental ratio provide valuable information about the intended use, the production process, and the purification process of Pu and mixed oxide (MOX) fuels. We demonstrate the ability to directly measure U and Pu isotopes from MOX fuel particles using the U.

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We demonstrate use of the Naval Ultra-Trace Isotope Laboratory's Universal Spectrometer (NAUTILUS) at the U.S. Naval Research Laboratory (NRL) to measure 236U directly from uranium-bearing particles free from molecular isobaric interferences.

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Understanding the release and sequestration of specific radioactive signatures into the environment is of extreme importance for long-term nuclear waste storage and reactor accident mitigation. Recent accidents at the Fukushima and Chernobyl nuclear reactors released radioactive Cs and Cs into the environment, the former of which is still live today. We have studied the migration of fission products in the Oklo natural nuclear reactor using an isotope imaging capability, the NAval Ultra-Trace Isotope Laboratory's Universal Spectrometer (NAUTILUS) at the US Naval Research Laboratory.

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