Hydroxyapatite Barriers for Radionuclide Containment

Technology Marketing SummaryApatite, which has been shown to effectively bind and immobilize radionuclides, can also be used to form barriers in water and soil in contaminated environments. The apatite barrier is formed in situ in soil by injection of chelated calcium, phosphate and fluoride solution. In situ formed apatite can be used to sequester actinides, strontium, lead, heavy metals and other compounds that react with apatite.DescriptionThis technology has been effectively applied at the Hanford site to create a barrier between the contamination areas, ground water, and nearby water sources such as the Columbia River. Due to the rising and falling of the water levels of the river, containment and an effective barrier is imperative to protecting from the spread of contamination. This technology has been shown to reduce the risks associated with sites containing hazardous materials and can be a critical component in maintaining a safe environment, protecting natural resources, and further mitigating associated risks.Benefits

• Contains and “holds” compounds that react with apatite which are hazardous to the environment
• Most effective method in the cleanup at Hanford site
• Creates a barrier in soil and groundwater

Applications and Industries

• Ground and surface water protection of contaminated sites
• Radioactive waste clean up
• Containment of radionuclides

Patents and Patent Applications

ID Number	Title and Abstract	Primary Lab	Date
Patent 6,416,252	In situ formation of phosphate barriers in soil Reactive barriers and methods for making reactive barriers in situ in soil for sequestering soil ontaminants including actinides and heavy metals. The barrier includes phosphate, and techniques are disclosed for forming specifically apatite barriers. The method includes injecting dilute reagents into soil in proximity to a contamination plume or source such as a waste drum to achieve complete or partial encapsulation of the waste. Controlled temperature and pH facilitates rapid formation of apatite, for example, where dilute aqueous calcium chloride and dilute aqueous sodium phosphate are the selected reagents. Mixing of reagents to form precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.	Sandia National Laboratories	07/09/2002 Issued
Patent 6,592,294	Situ formation of apatite for sequestering radionuclides and heavy metals Methods for in situ formation in soil of a permeable reactive barrier or zone comprising a phosphate precipitate, such as apatite or hydroxyapatite, which is capable of selectively trapping and removing radionuclides and heavy metal contaminants from the soil, while allowing water or other compounds to pass through. A preparation of a phosphate reagent and a chelated calcium reagent is mixed aboveground and injected into the soil. Subsequently, the chelated calcium reagent biodegrades and slowly releases free calcium. The free calcium reacts with the phosphate reagent to form a phosphate precipitate. Under the proper chemical conditions, apatite or hydroxyapatite can form. Radionuclide and heavy metal contaminants, including lead, strontium, lanthanides, and uranium are then selectively sequestered by sorbing them onto the phosphate precipitate. A reducing agent can be added for reduction and selective sequestration of technetium or selenium contaminants.	Sandia National Laboratories	07/15/2003 Issued

Technology Status

Technology ID	Development Stage	Availability	Published	Last Updated
US Patent# 6,416,252 and US Patent 6,592,294	Production - Sandia has shown that this product has been successfully tested in a real-world environment under relevant conditions as illustrated at the Hanford site. Application further demonstrated to be effective with little to no changes necessary in this technology.	Available - Various license and partnering options are available. Please contact the Intellectual Property department to discuss.	04/09/2010	03/12/2013