New Initiatives in the Laboratory's Handling of Legacy Transuranic Waste

This aerial view of the transuranic waste inspectable storage project (TWISP) shows the six storage domes at TA-54. Since the mid-1990s, thousands of drums of solid mixed and transuranic waste have been retrieved from dense-pack arrays and transferred into the domes, where they are inspected at least weekly, and daily on any day when a staff member enters a given dome.

Anyone in the Laboratory who works with actinides potentially generates transuranic (TRU) waste destined for the Waste Isolation Pilot Plant (WIPP) in Carlsbad, N.M. Because a high volume of legacy TRU waste also exists in storage here, reducing waste volume and efficiently managing legacy waste are topics that should be of concern to us all.

The Lab's new programs for handling legacy waste date back to 1994–95 when the State of New Mexico intervened to request that nearly 17,000 drums of solid mixed and TRU waste be placed in an inspectable and retrievable configuration. So began the transuranic waste inspectable storage project (TWISP).

The drums had been stored for nearly 20 years at TA-54 on above-grade asphalt pads in dense-pack arrays under plywood, plastic, and soil. Facility and Waste Operations (FWO) Division ultimately retrieved the drums from three such pads, and after washing and venting them, transferred them into six domes at TA-54. Here, they are inspected weekly, at minimum, and daily on any day when a Laboratory staff member enters a given dome.

This massive compactor-known as "Big Blue"-has proved invaluable to the Decontamination Volume Reduction System (DVRS) Project, which is aimed at decreasing the profusion of space-wasting "RFP crates." Contaminated waste, ranging from glove boxes to air filtration systems, that was originally stored in large reinforced plywood crates is sorted, decontaminated, and fed to Big Blue, which reduces the waste into the black jumbles of metal at the bottom of the photo. The compressed waste will be repackaged either for shipment to WIPP or storage at Los Alamos.

And happily for both taxpayers and Lab administrators, TWISP was completed two years ahead of schedule and $18 million under budget.

Another concern in the arena of TRU waste management has been the profusion of what are known as "RFP crates"-Fiberglas™-reinforced boxes containing a diversity of equipment ranging from glove boxes to high-efficiency particulate air (HEPA) filtration systems contaminated with both TRU and other types of waste, such as beryllium and low-level waste (LLW).

Often these crates are very large, and almost always, the items inside were packaged without much attention to space efficiency. This waste issue has spawned the Decontamination Volume Reduction System (DVRS) Project, an initiative to process RFP crates by characterizing their waste, reducing its volume, and enclosing it in crates for shipment to WIPP if TRU, or storage at Los Alamos if LLW. A relative of a good old-fashioned "Escort-Eldorado equalizer" proved invaluable in this project.

The basic methodology involves unsheathing each crate, segregating its waste (if relevant) into TRU and LLW, and if feasible, decontaminating each component by such techniques as paint-stripping, surface abrasion, and the use of chemical cleaners and surfactants. Each component is then reduced in volume by "Big Blue," a massive compactor, kin to those that compress both luxury and subcompact vehicles into the rectangular jumbles of metal that we often see being transported to recycling sites.

The resulting secondary waste must then be repackaged to meet WIPP-approved procedures if TRU, and Los Alamos waste acceptance criteria if LLW. And because safety is always first priority, the DVRS facility has a double firewall, each wall rated for a two-hour fire protection delay. Along the way, other techniques have proved useful during this process of waste categorization and reduction. For example, gas sampling of the crate interiors allows the detection of explosive or acid gases, mercury vapor, and loose radiological contamination.

Los Alamos implemented the transuranic waste inspectable storage project—or TWISP—as a way to make thousands of drums of legacy waste more inspectable and retrievable. Before TWISP, drums of waste were buried on pads in dense-pack arrays under plywood, plastic, and soil. Here, workers uncover drums from an array before washing, venting, and moving them to domes at TA-54. Waste drums from three such pads have been retrieved.

And during the FWO Division's exploration of options for noninvasive crate-content identification, an ingenious gamma-radiography adaptation was proposed. Because many crates are larger than the size limits of most radiography machines, a solution was discovered in the form of the machines used by Border Patrol agents to scan tractor-trailer rigs for drugs and/or illegal immigrants—machines large enough to handle most or all RFP crates.

Unfortunately, the events of Sept. 11 necessitated a temporary withdrawal of the offer of radiography personnel participation in the screening project, but it is hoped that this aspect of the operation will soon become reality.

There are also technological improvements in the offing in the waste-reduction arena. For example, a carbon dioxide decontamination blaster has shown promise in removing surface layers of actinide-contaminated items. The blaster produces a residue from which carbon dioxide evaporates, leaving a greatly reduced volume of TRU and an actinide-decontaminated remainder that can be disposed of as LLW. Other chemical-decontamination methods are also being researched.

"If we can get the money to do this stuff, we will," said Ray Hahn of Solid Waste Operations (FWO-SWO). One possible source of income may be the FRPs from other laboratories in the DOE complex. If an acceptable means of transport to Los Alamos can be found for their FRPs, Lawrence Livermore and other laboratories may ship them here for decontamination and reduction on a fee basis.

Vin LoPresti

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