Hybrid extractive scintillator resin for simultaneous concentration and detection of plutonium from aqueous solutions.

A scoping study of a commercially available resin selective for aqueous plutonium (Pu), AnaLig® Pu-02, modified with scintillator was investigated as a scheme to simultaneously concentrate and detect Pu in aquatic matrices. The extractive scintillating resin was comprised of a silica base, functionalized for plutonium extraction, grafted with plastic scintillator of polyvinyl toluene (PVT) and 2-(1-naphthyl)-4-vinyl-5- phenyloxazole (vNPO) fluor. Scintillator was incorporated onto the AnaLig® Pu-02 resin in a two-step process of silanization followed by surface-polymerization. Successful modification was facilitated by grinding the resin beads prior to silanization to expose cleaved silica surface sites appropriate for scintillator grafting. The modified resin was subjected to initial characterization of batch uptake and radioluminosity measurements where a total detection efficiency of 32.5% was observed. The modified resin was then subjected to pH 1 simulants containing environmental relevant groundwater constituents of varying concentration. Concentrations of 0.001M Fe(III) interfered with Pu uptake, while concentrations of up to 0.01M Ca(II) and 0.001 mM concentration of natural uranium and thorium had minimal influence on plutonium uptake. A translucent column packed with the modified AnaLig® Pu-02 was placed in a commercial flow-cell radiation detector for real-time detection of plutonium; a total detection efficiency of 20.4% was achieved for on-line measurements. The modification of AnaLig® Pu-02 results in a minimum detection limit capable of meeting the EPA limit for gross alpha activity in drinking water given a sufficient counting time of 15 min and approximately 300 mL of solution volume.

Uranium in hot water tanks: a source of TENORM.

Uranium deposits were detected inside hot water tanks using gamma-ray spectroscopic techniques and corroborated by the difference in the uranium concentration of the groundwater entering and leaving the hot water tanks. In-situ gamma-ray spectroscopy was performed using a transportable high-purity germanium (HPGe) gamma-ray spectrometer to estimate the mass of uranium in the hot water tanks. Gamma-ray spectroscopic analyses of hot water tanks in four residences with groundwater uranium concentration between 732 and 7,667 mug L revealed an estimated 3.5 to 69 g of uranium in each hot water tank. The uranium deposit within the tanks was indicated by the 143.8, 163.4, and 185.7 keV gamma rays of U and confirmed with the 63.3, 92.3, and 92.8 keV gamma rays of Th as well as the 1,001 keV peak of Pa. An average decrease in uranium concentration of 23% was observed in the groundwater that passed through the hot water tanks. Additionally, once "uranium free" water entered the hot water tanks, the uranium deposits within the tanks resulted in an increase in the uranium concentration in the effluent water. The groundwater had an alkalinity in the range of 46-96 mg L as CaCO3 and a pH range of 7.3-8.1. The accumulation of uranium in these hot water tanks results in them being classified as technologically enhanced naturally occurring radioactive materials (TENORM).