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This contribution characterizes the stability of scintillating resins for ionizing radiation detection that were synthesized with 2-(1-naphthyl)-5-phenyloxazole (α-NPO) or 2-(1-naphthyl)-4-vinyl-5-phenyloxazole (v-NPO) fluor in polystyrene (PS) or poly(4-methyl styrene) (PVT) matrices. Leaching studies of the PS and PVT resins with methyl acetate show a 60 % reduction in luminosity and 80 % reduction in detection efficiency for α-NPO samples; while v-NPO resins retained detection properties. Degradation studies indicate the nitration of PS resins and the fluors after nitric acid exposure, resulting in a 100 % reduction in optical properties; whereas PVT resins with v-NPO fluor maintained 20 % detection efficiency. Heuristics are reported for designing stable scintillating resins. [ABSTRACT FROM AUTHOR]

This contribution details the application of extractive scintillating resin with covalently bound fluorophore, v-NPO, and ligand, methyl phosphonic acid, in flow-cell experiments utilizing varying column diameters, resin diameters and diffusion times. The detection efficiency was evaluated by standard offline liquid scintillation counting methods. Diffusion experiments were conducted to determine the effect of the location of the alpha decay on detection efficiency, and the data were compared to a diffusion model to assess the feasibility of relying on diffusion-enhanced detection efficiency in an online measurement. [ABSTRACT FROM AUTHOR]

False positive and false negative incidence rates of radiological monitoring data from classical and Bayesian statistical process control chart techniques are compared. The on-line monitoring for illicit radioactive material with no false positives or false negatives is the goal of homeland security monitoring, but is unrealistic. However, statistical fluctuations in the detector signal, short detection times, large source to detector distances, and shielding effects make distinguishing between a radiation source and natural background particularly difficult. Experimental time series data were collected using a 1″ × 1″ LaCl3(Ce) based scintillation detector (Scionix, Orlando, FL) under various simulated conditions. Experimental parameters include radionuclide (gamma-ray) energy, activity, density thickness (source to detector distance and shielding), time, and temperature. All statistical algorithms were developed using MATLAB™. The Shewhart (3-σ) control chart and the cumulative sum (CUSUM) control chart are the classical procedures adopted, while the Bayesian technique is the Shiryayev–Roberts (S–R) control chart. The Shiryayev–Roberts method was the best method for controlling the number of false positive detects, followed by the CUSUM method. However, The Shiryayev–Roberts method, used without modification, resulted in one of the highest false negative incidence rates independent of the signal strength. Modification of The Shiryayev–Roberts statistical analysis method reduced the number of false negatives, but resulted in an increase in the false positive incidence rate. [ABSTRACT FROM AUTHOR]

Aqueous tritium enrichment parameters of a commercially available Iridium/Platinum (Ir/Pt) polymer electrolyte membrane (PEM) cell were determined after electrolysis of tritium aqueous standards, and compared to those of a conventional Nickel/Iron (Ni/Fe) electrochemical cell. Lower aqueous enrichment is seen in the Ir/Pt PEM electrolyzer in comparison to the conventional Ni/Fe electrolytic cell. This is explained by the values found for the PEM cell fractionation factor βIr/Pt and electrolytic fractionation factor β eIr/Pt values determined to be 4.7 ± 0.3 ( βNi/Fe = 26), and 6.6 ± 0.7 ( β eNi/Fe = 37), respectively. A direct consequence of the Ir/Pt β e value is the richer tritium gas phase produced relative to the conventional cell, which is advantageous for direct reduction of HTO to HT gas. [ABSTRACT FROM AUTHOR]

The combination of an Ir/Pt PEM electrolyzer with a 1 L flow-through gas proportional counter was characterized for the quantification of tritium in water. The goal of the detection system is to quantify at concentrations below the Environmental Protection Agency (EPA) primary drinking water standard (740 Bq/L) with minimal expendables. The detector operating voltage, efficiency, background count rate of the passively shielded counter were measured in order to calculate the minimum detectable concentration of the detection system. The electrolyzer fractionation factor β e value deduced from the measurement of gas phase activity concentrations generated from tritium aqueous standards was found in good agreement with literature values. [ABSTRACT FROM AUTHOR]

Characterization of SuperLig® 620 solid phase extraction resin was performed in order to develop an automated on-line process monitor for 90Sr. The main focus was on strontium separation from barium, with the goal of developing an automated separation process for 90Sr in high-level wastes. High-level waste contains significant 137Cs activity, of which 137mBa is of great concern as an interference to the quantification of strontium. In addition barium, yttrium and plutonium were studied as potential interferences to strontium uptake and detection. A number of complexants were studied in a series of batch Kd experiments, as SuperLig® 620 was not previously known to elute strontium in typical mineral acids. The optimal separation was found using a 2 M nitric acid load solution with a strontium elution step of ~0.49 M ammonium citrate and a barium elution step of ~1.8 M ammonium citrate. 90Sr quantification of Hanford high-level tank waste was performed on a sequential injection analysis microfluidics system coupled to a flow-cell detector. The results of the on-line procedure are compared to standard radiochemical techniques in this paper. [ABSTRACT FROM AUTHOR]

The research presented here is the development of sensor materials that are applicable for real-time in situ quantification of radiostrontium in aqueous solutions. Two different approaches were applied to prepare highly selective structures for simultaneous extraction and detection of radiostrontium using online detection methods. Online data were acquired with a flow scintillation analyzer IN/US β-Ram model 5 (LabLogic Systems, Inc) with a 30-s dwell time. Both approached utilized the commercially available SuperLig620 solid-phase extractant (IBC Technologies, Inc.) to concentrate the strontium in combination with a scintillator to quantify the radioactivity. [ABSTRACT FROM AUTHOR]

A colorimetric method was developed for the determination of uranium in groundwater. The detection limit for the method is approximately 25 μg/L uranium, which is below the maximum contaminant level for uranium in drinking water, 30 μg/L. The method is rapid and requires little technical training to conduct, allowing it to be used by consumers, in the laboratory, or in the field. The two-step technique involves preconcentrating uranium using a U/TEVA-2 extraction chromatographic resin followed by complexation with a pyridylazo indicator dye, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. If color change is visible to the eye, the concentration of uranium in groundwater is above the detection limit. Preconcentration using U/TEVA-2 also serves to eliminate metals that may interfere with the quantification of uranium. [ABSTRACT FROM AUTHOR]