Transuranics away from home

When Los Alamos programs call for performing experiments with transuranics at a synchrotron x-ray source, how do you do it?

There are only three light sources in the United States: Stanford Synchrotron Light Source, Argonne National Laboratory, and Brookhaven National Laboratory. Less than 1 ppm of plutonium in a 200-mg Rocky Flats concrete sample may be close to an exempt quantity, but Pu-238-spiked alloys or Hanford tank sludges with contact doses of 20 mrem/hr per hour begin to approach the limits for these nonnuclear facilities. And when the sample is a salt in a beryllia holder that is supposed to be melted at 800 °C or an electrochemical cell, then handling even a few milligrams of plutonium becomes a problem.

The answer to this question is to temporarily construct a piece of equipment like that used in Los Alamos' Plutonium Facility (PF-4) at the experimental site.

To safely study transuranics at the Stanford Synchrotron Light Source, researchers had to outfit the experimental area with controlled, filtered ventilation and continuous air monitors.

By working with personnel from Los Alamos' Health Physics Operations Group--integrated safety management long before the phrase was in common use--sample holders are designed, fabricated, tested, loaded, and shipped to the synchrotron, where both the transfer (samples can never be enclosed in less than three layers of containment at any time) and experimental areas have been outfitted with controlled, HEPA-filtered ventilation, continuous air monitors, and other equipment far less common at the light sources than it is here.

While Los Alamos radiological control technicians place samples in tertiary containers and mount them in the diffractometer or on the XAFS sample positioner and monitor the operations, the scientists on the team heat, cool, and electrolyze the samples and perform the actual measurements according to the 24/7 synchrotron schedule.

Although many measurements on transuranics had already been performed at synchrotrons--including many by Los Alamos--prior to the initiation of this program, this was nevertheless the first time that a long-term program of this type was proposed involving many different types of materials and conditions on a continuous basis, and just as the awareness of safety concerns began to be heightened. Conceived in 1991, during the Tiger Team era, the first experiments at the Stanford Synchrotron Light Source were performed in July 1993 after an approval process that took almost two years.

An aerial view of the Stanford Synchrotron Light Source.

Since that first 10-day run, scientists, technicians, and students from Los Alamos and many other institutions--including Argonne, Pacific Northwest and Oak Ridge National Laboratories; Great Britain's Atomic Weapons Establishment (AWE) France's Centre de Valduc; the Australian Nuclear Science and Technology Organization; the Institute of Transuranium Elements (ITU), Karlsrühe, Germany; the Paul Scherrer Institute; Rocky Flats; and a number of both foreign and U.S. universities--have collaborated in XAFS and x-ray-scattering measurements on transuranic-containing samples that require the unique properties of synchrotron radiation. These measurements provide results for programs concerned with weapons materials, nuclear fuels, environmental restoration, waste storage, separations chemistry, and other aspects of both basic and applied actinide chemistry and materials science.

Since this pioneering step by Los Alamos, many other groups have duplicated this feat, and measurements on transuranic samples have become so common that most light sources are now being equipped with dedicated facilities for radioactive samples.

And when we're done, we break it down, put it away until the next run, and return home to catch up on our sleep and analyze the data.

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