Video transcript (122KB PDF)
Rad-Release I Chemical Decontamination Technology is based on patented technologies developed by Idaho National Laboratory and licensed to Environmental Alternatives, Inc. of Keene, NH, for further development and commercialization. It is a chemical process that involves the topical application of a single decontamination solution to treat various substrates bearing radiological contamination. A second part using montmorillonte clay may be used, depending upon the decontamination requirements.
EAI’s Rad-Release I is designed and blended to extract the contaminants via the migration pathways, pores and capillaries of the contaminated material. It is effective for both loose surface and fixed subsurface contamination and situations in which the contamination is a mixture of pure elements, oxides, and related compounds with varying solubility indices. Substrates for which the process can be used include those that are both porous and seemingly nonporous. The technology can be deployed on various geometries including walls, ceilings, equipment, structural beams, internal piping and highly irregular surfaces.
To maximize the efficacy of the extraction process, the chemistry and application are tailored to the specific substrate, targeted contaminants and surface interferences. Rad-Release I uses a blend of organic and inorganic acids designed to reopen the pores and capillary pathways and cleave the electrostatic and chemical bonds binding the radiological contaminants to the substrate. The solution contains salts to promote ion exchange and surfactants to remove dirt, oil, grease and other surface interferences. Broad-target and target-specific chelants are blended into the solution to sequester and encapsulate the contaminants, keeping them in suspension until they are removed by the subsequent rinse.
The solution is applied in low volumes, as either an atomized spray or foam. Foam deployment of the solution has proven very practical for large scale applications while the spray application is beneficial for smaller applications and applications where waste minimization is a critical factor. After the decontamination solution is applied, light mechanical action is applied to ensure good contact with the contaminated surface. It is then left to reside for a prescribed amount of time followed by a rinse and removal. There are several options available to facilitate the removal step. The sequence of application, dwell, rinse, and removal of the decontamination solution constitutes a single iteration. It may be repeated, as needed, until the desired residual contaminant levels are achieved.
The blended solution contains no hazardous components regarding flammability or reactivity and has no components that would classify them as hazardous for disposal. As a result, the waste stream from a project can be characterized based on the contaminants that were removed. Liquid waste volumes are usually 0.01 to 0.05 gallon per square foot of contaminated substrate. Depending on the matrix and the amount of rinse applied, the liquid waste stream may be a resultant pH of less than 2. A pH neutral waste can be attained by stoichiometrically adding sodium bicarbonate or another neutralizing agent. Waste may be handled by solidification, incineration, discharged to liquid effluent treatment systems, and/or evaporation.
If additional decontamination is required, then montmorillonite clay, hydrated with potassium chloride, is sprayed or troweled onto the surfaces and left for 10 days to 6 weeks, depending upon the contaminant and the type of surface. Then, the clay can be removed by peeling or vacuuming, effectively removing up to 99 percent of the contamination.
Note: This summary was excised from the joint INL-EAI 2011 R&D 100 Awards submission.