· National Geospatial Intelligence Agency, “ENHANCED “HOT SUSHI” Lowering target isotope limits of detection for an existing design of a compact, high-resolution, in situ gamma counter for aqueous environments by enhancing on-board filtration and chemosorption capabilities”, for Postdoctoral Fellowship to Bryce, Johnson, Peter H. Santschi, PI, 2008-2010 ($240,000).

· Defense Intelligence Agency - MASINT Consortium (NCMR ID 06P07PNNLSchw), “Autonomous High-Resolution in-situ Gamma Counter for Monitoring Marine and Coastal Waters”, Peter H. Santschi, co-PI, Jon Schwantes (PNNL), Peter H. Santschi, Co-PI, 2007-2010 ($168,000).

· National Consortium for Measurement and Signature Intelligence (MASINT) Research Program, Naval Postgraduate School - “Chemisorption Studies of Selected Radionuclides for Use in Autonomous Collection and In-Situ Detection Systems for Monitoring Marine and Coastal Waters”, Peter H. Santschi, PI, 2013-2014 ($167,477).

The purpose of this collaborative project with researchers at Pacific Northwest Laboratory was to aid in developing a compact, high-resolution, in situ gamma counting system for marine and coastal waters. This design initiative will utilize a compact high-resolution gamma counter (either CdZnTe (CZT) or LaBr3), incorporating filtration and chemo-sorption to pre- concentrate target isotopes prior to counting in order to minimize detector size, lower limits of detection (LOD), and reduce overall count time. The final system will be platform independent but designed for compatibility with a man-portable “Autonomous Underwater Vehicle” or a moored buoy deployment platform.

Summary:

The purpose of this project is to develop a compact, high-resolution, in situ gamma counting system for marine and coastal waters. This design initiative will utilize a compact high-resolution gamma counter (either CdZnTe (CZT) or LaBr ), incorporating filtration and chemo-sorption to pre-concentrate target isotopes prior to counting in order to minimize detector size, lower limits of detection (LOD), and reduce overall count time. The system will be platform independent but designed for compatibility with a man-portable “Autonomous Underwater Vehicle” or a moored buoy deployment platform.

Technical Objectives: Component development and tasking for this project follows two parallel tracts: (i.) incorporation of tried and true technologies to minimize development time and ensure a high probability of success; and (ii.) development of novel (higher risk) technologies that, if successfully incorporated, would represent significant enhancement in performance over the tried and true technologies. Certain components of this research may be considered “High-risk,” such as the use of novel filtration systems, technologies like recyclable centrifugal filtration or disposable variable-porosity packed-bed column filtration. The successful incorporation of these technologies could provide a means for increasing filter capacity (and correspondingly decreasing LOD), by orders of magnitude. They may also provide the ability to define the target particle diameter on the fly during a deployment without an increase in the overall size of the apparatus.

Use of nano-technology to enhance chemosorbant performance, specifically, nano-surfaces like self-assembled monolayers on meso-porous supports (SAMMS) may be used in place of more traditional chemosorbants as the supporting material for the chemosorbant functional groups. These functionalized nano-surfaces increase the effective surface area and/or concentration of surface functional groups (i.e., capacity), by several orders of magnitude over traditional chemosorbants thereby having the effect of proportionally decreasing the LOD of the system.
The IC Post Doctoral Fellowship recipient was directing the novel, high-risk, research aspects of this project with the goal of enhancing the overall performance of the in situ gamma counting system.

Goals: The goals of the IC Fellowship recipient would be to enhance pre-concentration capabilities of the in situ gamma detection system by: (i.) replacing traditional membrane filtration units with a novel filter designed to minimize clogging, increase capacity, and/or provide a means for adjusting porosity on the fly; (ii.) utilizing nano-size functionalized surfaces to enhance chemosorbant capacity and lower LOD for dissolved target isotopes.

Publications:

• Johnson, B.E., Santschi, P.H., Addleman, R.S., Douglas, M., Davidson, J., and Schwantes, J. 2011. Collection of fission and activation product elements from fresh and ocean waters: a comparison of traditional and novel sorbents. Applied Radiation and Isotopes, 69, 205–216.
• Johnson, B.E., Santschi, P.H., Addleman, R.S., Douglas, M., Davidson, J., Schwantes, J. 2011. Optimization and Evaluation of Mixed-Bed Chemisorbents for Extracting Fission and Activation Products from Marine and Fresh Waters, Analytica Chimica Acta 708, 52– 60.
• Johnson, B.E., Santschi, P.H., Chuang, C.-Y., Otosaka, S., Addleman, R.S., Rutledge, R.D., Chouyyok, W., Davidson, J., Fryxell, G.E., Schwantes, J.M. 2012. Collection of Lanthanides and Actinides from Natural Waters with Conventional and Nanostructured Sorbents. Environmental Science and Technology, 46, 11251−11258.
• Schwantes, J.M., and Santschi, P.H. 2010. Mechanisms of Plutonium sorption to mineral oxide surfaces: New insights with implications to colloid-enhanced migration. Radiochim. Acta, 98(9-11), 737-742.

Dr. Peter H.Santschi
Professor
Department of Marine Sciences
1001 Texas Clipper Rd
Bld# 3029, Office 346
Galveston, TX, 77554 USA

E-mail: santschi@tamug.edu
Phone: (409) 740-4476
Fax: (409) 740-4786