Lab researchers have developed two sprayon/peel-off coatings that could be used by federal emergency response teams to prevent the further spread of radiological contamination and, later, cleanse radionuclides from contaminated surfaces following a dirty bomb attack or other radiation incident.
The first, a containment coating, is impervious to weather once it dries and can be used by the earliest federal responders to ensure radionuclides stay in place until evidence is gathered and cleanup begins, says project manager Joe Jones of Radiological Consequence Management & Response Dept. 6874.
The second, a hydrogel for decontamination of porous surfaces, can help restore radiation-contaminated construction materials — such as concrete, brick, marble, and granite — to usable condition, says principal investigator and inventor Bob Moore of Advanced Nuclear Concepts Dept. 6872. The decontamination hydrogel was developed jointly with Mark Tucker (6245). Chemical getters in the liquid hydrogel solution quickly grab onto radionuclides in the pores of the materials and hold the contaminants in their molecular structures until the hydrogel dries.
Once dried, both coatings can be peeled off the surface and disposed of as radiological waste.
Chemically both coatings contain advanced water-soluble polymers with an oxidative crosslinking additive such as sodium borate. The crosslinker allows the polymers to remain as a liquid — individual molecules suspended in a water-solvent solution — until activated by, for example, the oxygen in open air.
Once activated, the polymers begin to chemically join into strands (for the containment coating) or balls (for the hydrogel). A network of these polymer chains or balls form as the water and solvents evaporate from the structure, leaving a hardened, water-insoluble plastic than can be peeled off a surface.
Both coatings go on like paint and dry like the latex of a party balloon. Drying times for both coatings can be tailored to need, from less than an hour to more than a day.
Sandia developed the containment coating as part of a Department of Homeland Security program to secure a scene following a radiation incident.
Sandia initially developed the hydrogel as part of a DARPA call for proposals in 2004.
Although DARPA has chosen not to move forward with the hydrogel, the Sandia researchers say both technologies are ripe for commercialization.
“Basically the first responder community has said they want more tools in their tool boxes to deal with a broader range of threats, including a dirty bomb incident,” says Bob.
“We needed something that dries fast and is easily removable and meets the needs of the earliest federal responders,” says Joe. “In laboratory tests, both coatings have been effective for their intended purposes.”
Ideally, adds Bob, the two technologies could be combined into a single containment-decon coating product.
The Sandia team has sought to minimize costs by using inexpensive, off-the-shelf chemicals as constituents.
Patent applications are being prepared for both coatings.