5 Matching Results

Search Results

Advanced search parameters have been applied.

Determination of iodine to compliment mass spectrometric measurements

Description: The dose of iodine-129 to facility personnel and the general public as a result of past, present, and future activities at DOE sites is of continuing interest, WINCO received about 160 samples annually in a variety of natural matrices, including snow, milk, thyroid tissue, and sagebrush, in which iodine-129 is determined in order to evaluate this dose, Currently, total iodine and the isotopic ratio of iodine-127 to iodine-129 are determined by mass spectrometry. These two measurements determine the concentration of iodine-129 in each sample, These measurements require at least 16 h of mass spectrometer operator time for each sample. A variety of methods are available which concentrate and determine small quantities of iodine. Although useful, these approaches would increase both time and cost. The objective of this effort was to determine total iodine by an alternative method in order to decrease the load on mass spectrometry by 25 to 50%. The preparation of each sample for mass spectrometric analysis involves a common step--collection of iodide on an ion exchange bed. This was the focal point of the effort since the results would be applicable to all samples.
Date: November 1, 1994
Creator: Hohorst, F.A.
Partner: UNT Libraries Government Documents Department

A process for determining radiohalogens

Description: Techniques for the separation and potential determination of chlorine-36 and iodine-129 were examined. Separation was based upon addition to the carbon-carbon double bond in 1-hexene. These specific organic halides formed an acceptable liquid scintillation counting cocktail with chlorine but not with iodine. The miscibility of 1,2-dichlorohexane should allow a larger mass of sample in a scintillation cocktail, lowering the detection limit of the determination of chlorine-36. Organic halides are also expected to be more receptive to waste treatment than metals such as silver. These techniques offer the potential for determination of chlorine-36 in groundwater samples while producing less mixed waste than current analytical techniques.
Date: December 1, 1993
Creator: Washington, W.J. & Hohorst, F.A.
Partner: UNT Libraries Government Documents Department

Determination of radium in water

Description: These detailed work instructions (DWIs) are tailored for the analysis of radium-226 and radium-228 in drinking water supplies from ground water and surface water sources and composites derived from them. The instructions have been adapted from several sources, including a draft EPA method. One objective was to minimize the generation of mixed wastes. Quantitative determinations of actinium-228 are made at 911 keV. The minimum detection level (MDL) for the gamma spectrometric measurements at this energy vary with matrix, volume, geometry, detector, background, and counting statistics. The range of MDL`s for current detectors is 0.07 to 0.5 Bq/sample. Quantitative determinations of radium-226 are made by counting the high energy alpha particles which radium-226 progeny emit using liquid scintillation counting (LSC). The minimum detectable activity (MDA) is 3.8 E-3 Bq/sample. The maximum concentration which may be counted on available instruments without dilution is about 2 E + 5 Bq/sample. Typically, this determination of radium in a 2 L sample has a yield of 80%. If radium-228 is determined using a 16 h count after 50 h grow-in, the typical MDL is 1 E-9 to 8 E-9 {mu}Ci/mL (1 to 8 pCi/L). If radium-226 is determined using a 2.5 h count after 150 h grow-in, the typical MDA is about 1 E-10 {mu}Ci/mL (0. 1 pCi/L).
Date: October 1, 1995
Creator: Hohorst, F.A.; Huntley, M.W. & Hartenstein, S.D.
Partner: UNT Libraries Government Documents Department

Partitioning of krypton-85 in liquid scintillation cocktail

Description: Krypton is one of the noble gases. As such, it forms compounds only with exceptionally strong oxidizing agents. The concentration of krypton in air is 1.139 parts per million by volume. In general, its behavior is best described as that of an ideal gas. Krypton-85 is the longest lived of the common radioactive noble gases with a half life of 10.72 years. Gamma radiation at 513.990 keV has an intensity of only 0.434%. Most decay is {beta}{sup -} emission with a maximum energy of 687.0 keV and an average energy of 251.4 keV. The analytical chemistry of krypton-85 is driven by these factors. High concentrations may be gamma counted directly. Low levels are typically determined by more sensitive techniques such as liquid scintillation counting (LSC) where detection limits on the order of 1 picocurie (pCi) are routinely achieved. For a 5 standard cubic centimeter (scc) sample, this represents a concentration of 0.2 pCi/scc, well below the DOE Air Immersion Derived Concentration Guideline (G) of 3 pCi/scc. As a gas, krypton in a sealed LSC vial distributes itself between the liquid phase and the gas phase. Some past work has used gamma counting at levels many orders of magnitude greater than those now achievable by LSC to study the distribution of krypton. This effect is of interest in the analytical chemistry of krypton-85 because geometrical considerations influence how much of the material in the gas phase decays generating particles which then impact the liquid phase where they may be counted.
Date: December 1, 1994
Creator: Hohorst, F. A. & Sherlock, M. A.
Partner: UNT Libraries Government Documents Department

Determination of low specific activity iodine-129 off-gas concentrations by GC separation and negative ionization mass spectrometry

Description: This document is the final report of the laboratory development of a method for determining the specific activity of the /sup 129/I emitted from a nuclear fuel reprocessing plant. The technique includes cryogenic sample collection, chemical form separation, quantitation by gas chromatography, and specific activity measurement of each chemical species by negative ionization mass spectrometry. The major conclusions were that both organic and elemental iodine can be quantitatively collected without fractionation and that specific activity measurements as low as one atom of /sup 129/I per 10/sup 5/ atoms of /sup 127/I are possible.
Date: September 1, 1983
Creator: Fernandez, S.J.; Rankin, R.A.; McManus, G.J.; Nielsen, R.A.; Delmore, J.E.; Hohorst, F.A. et al.
Partner: UNT Libraries Government Documents Department