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Understanding the Effects of the Addition of Supplemental Inorganic Sequestering Materials to Inhibit the Release of Radionuclides from Cementitious Waste Forms with Nuclear Magnetic Resonance Spectroscopy

EMSL Project ID


Immobilization in cementitious materials is a commonly employed method of remediation of low- and intermediate-level radioactive and hazardous species around the world. Indeed, the baseline method of solidification of aqueous secondary liquid effluents from the Hanford Tank Waste Treatment and Immobilization Plant (WTP) process condensates and low-activity waste (LAW) melter off-gas caustic scrubber effluents is in a cementitious material known as Cast Stone. The material is also being evaluated as a supplemental immobilization technology to provide the necessary LAW treatment capacity to meet Hanford closure deadlines. When evaluating the shallow surface disposal of Cast Stone at the Hanford site, the common method is to employ a diffusion-limited model for the release of technetium-99 and iodine-129, two of the radioactive tank waste components that contribute the most to environmental impacts associated with the cleanup of the Hanford Site. Presently, the effective Tc and I diffusivities from Cast Stone into the surrounding environment give concentrations that exceed the maximum allowable value in groundwater at the 100-m gradient well. Therefore, in order to improve the effectiveness of the cementitious Cast Stone waste form, it has been proposed to add supplemental inorganic sequestering materials, known as a “getters”, which remove technetium-99 and iodine-129 from solution and lower the diffusivity of Tc and I to acceptable levels. Several suitable candidate materials have been identified to achieve this goal.
The goal of this proposal is to further characterize the getter materials in order to understand the processes involved in Tc and I immobilization and, in turn, complete publications on previously performed getter work. By doing so, the radionuclide removal process can be refined and further development can be achieved. For this proposal, we aim to see if the addition of the getter material alters the phases found in the Cast Stone product with the use of Nuclear Magnetic Resonance (NMR) Spectroscopy.

Project Details

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Principal Investigator

Nikolla Qafoku
Pacific Northwest National Laboratory

Team Members

James Neeway
Pacific Northwest National Laboratory

Related Publications

Asmussen R.M., J.J. Neeway, A.R. Lawter, T.G. Levitskaia, W.W. Lukens, and N. Qafoku. 2016. "The Function of Sn(II)-Apatite as a 99-Tc Immobilizing Agent." Journal of Nuclear Materials 480. PNNL-SA-114465. doi:10.1016/j.jnucmat.2016.09.002