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Abstract  

A new digital filter has been investigated for removing low-frequency periodic noise from the output signal of hyper-pure germanium detectors (HPGe). Sources of noise examined include microphonics and simulated low-frequency noise (via input sinusoidal wave forms). In this paper, three distinctly different detector/mechanical-cooler combinations were investigated. Removal of the periodic noise induced from “outside” environmental sources, such as ground loops, is investigated using an input sinusoidal wave generator. The LFR not only improved spectral resolution across all energies in two of three detector/mechanical cooler combinations, but also removed simulated periodic noise from 100 to 3 kHz.

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Abstract  

We have developed a sequential extraction technique for determining the geochemical partitioning of Am, Pu, and U in soils and sediments. Stable element analyses were combined with radiometric measurements to determine the most probable geochemical host phases of these actinides in reference sediment IAEA-135.241 Am results indicate an association with carbonate minerals and organic matter. The extraction profile of238U was similar to that of refractory elements Al, Ti, and K.239/240Pu data suggest a fractionation of Pu into Fe-bearing phases of varying solubility. The reproducibility of the method was quite good (replicates agreed to within 10% at a 95% confidence level).

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Abstract  

Remote-handled transuranic nuclear waste poses a particular challenge for assaying due to the high neutron and -ray background that emanate from the non-fissile, but highly radioactive material, contained within the waste. The utilization of a Radio Frequency Quadrupole (RFQ) linac with a neutron flux of the order of 1010 n/s/4 has shown that, in principle, the differential die-away technique can be used to reliably assay this special class of nuclear waste.

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Abstract  

The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN USA) provides natural-matrix human urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. Samples are provided to these laboratories as “single-blind” or “double-blind” unknowns, spiked with radioactive-solution standards at “low” levels (e.g., 0–250 mBq·kg−1 for alpha-emitters). Participants use the results as a tool for self-evaluation and a measure of performance. In this paper, sample preparation and the results of testing during the years 2000–2004 for the radionuclides natural uranium (U-nat), 238Pu, 239Pu, and 241Am are presented and discussed.

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Abstract  

The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN USA) provides natural-matrix human urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. Samples are provided to these laboratories as “single-blind” or “double-blind” unknowns, spiked with radioactive-solution standards at “low” levels (e.g., 0.7–7 Bq g−1 for 3H and 0.7–7 Bq kg−1 for 90Sr). Participants use the results as a tool for self-evaluation and a measure of performance. In this paper, sample preparation and the results of testing during the years 2001–2005 for 3H and 90Sr are presented and discussed.

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Abstract  

The analysis of environmental samples for low levels of U, Pu, Am and other actinide elements is often hampered by sample-dependent problems involving the composition and/or mineralogy of specific samples. While relatively small samples (1–2 g of soil or 1–2 of water) are required to reach the extremely low detection limits occasionally mandated for environmental monitoring. One approach to avoid the troublesome and often inexplicable problems collectively referred to as matrix effects is to pre-concentrate actinides into a common form that would then behave uniformly and predictably during a subsequent separation scheme. Recently, a new extraction chromatographic resin based on diphosphonate chemistry was developed at Argonne National Laboratory. This resin commercialized as Eichrom's Actinide Resin, exhibits extremely high affinity for actinide elements even in the presence of high concentrations of salts. We have measured the uptake of actinides by the Dipex® extractant from natural waters and natural matrix soil standards. Water samples have been analyzed for gross -activities and gave results that compared favorably to the traditional approach. In addition, we have obtained good recoveries and excellent separations for soil samples as judged by resolution on the -spectra and the complete absence of interfering energies.

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Abstract  

The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN, USA) provides natural-matrix urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. In 2003, a single laboratory (Los Alamos National Laboratory LANL, Los Alamos NM USA) requested a change in the test-samples provided previously by the ISP. The change was requested to evaluate measurement performance for analyses conducted using thermal-ionization mass spectrometry (TIMS). Radionuclides included 239Pu at two activity levels (75–150 μBq·sample−1 and 1200–1600 μBq·sample−1) and 238Pu (3700–7400 μBq·sample−1). In addition, 240Pu was added to the samples so that the 239+240Pu specific activity was 3700–7400 μBq·sample−1. In this paper, the results of testing during the period May, 2003 through September, 2005 are presented and discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Inn
,
E. Hall
,
J. Woodward
,
B. Stewart
,
R. Pollanen
,
L. Selvig
,
S. Turner
,
I. Outola
,
S. Nour
,
H. Kurosaki
,
J. LaRosa
,
M. Schultz
,
Z. Lin
,
Z. Yu
, and
C. McMahon

Abstract  

Recoil ions from alpha-particle emission can contaminate surface-barrier detection systems. This contamination results in increased measurement uncertainty, and may require the replacement of expensive detectors. Disposable thin Collodion films are easily prepared and effectively retard the recoil ions when either directly applied to the surface of alpha-sources or as catcher foils between the source and the detector. The thin films are particularly effective for relatively low-level sources, but can sustain structural damage when exposed to high levels of recoil ions (tens of thousands per second) over extended periods of time.

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