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Abstract  

The complexation of plutonium(IV) with sulfate at variable temperatures has been investigated by solvent extraction method. A NaBrO3 solution was used as holding oxidant to maintain the plutonium(IV) oxidation state throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-HSO4 complexes, dominant in the aqueous phase, were calculated from the effect of [HSO4 ] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures using the Van’t Hoff equation.

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Abstract  

The complexation of Np(V) with phosphate at elevated temperatures was studied by a synergistic extraction method. A mixed buffer solution of TRIS and MES was used to maintain an appropriate pH value during the distribution experiments. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of phosphate were increased. Stability constants of the 1:1 and 1:2 Np(V)-HPO4 2− complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [HPO4 2−] on the distribution ratio. The thermodynamic parameters including enthalpy and entropy of complexation between Np(V) and HPO4 2− at 25 °C–55 °C were calculated by the temperature coefficient method.

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Abstract  

Reduction of carbon dioxide (CO2) in the environment may avert the effects of global warming. One method to control CO2 emissions is to sequester it underground. Leakage from storage must be minimized for long-term control. Detection of leaks decreases the amount of CO2 released from storage, so onsite monitoring must be performed over large areas. Spiking the injected CO2 with an isotopic tracer can improve ground leak detection using fewer sampling stations, with greater accuracy than CO2 sensors and no interference from radon gas. The relative merits of sorbent materials, isotopic tracers, detection methods and potential interferences will be discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: P. Bachelor, J. Friese, C. Aalseth, J. McIntyre, H. Miley, R. Perkins, and G. Warren

Abstract  

In anticipation of a nuclear detonation, techniques to quickly assess the radiation exposure of evacuees should be developed. Based on experience relating neutron radiation exposures to activation products, measurement of activation products can be performed in a few minutes. Personal items exposed to significant levels of radiation allows neutron dose assessment via the activation products. This approach allows prompt collection of important data on human exposure following a nuclear attack. Data collected will facilitate triage decisions for emergency medical treatment to ameliorate the radiation effects on exposed individuals. Activation experiments with everyday items exposed to a neutron source are presented.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Douglas, J. Friese, G. Warren, P. Bachelor, O. Farmer, A. Choiniere, S. Schulte, and C. Aalseth

Abstract  

A project has been undertaken at Pacific Northwest National Laboratory (PNNL) to tailor a series of efficient chemical separations to allow the rapid quantification of gamma-ray emitting isotopes in mixed fission product (MFP) samples. In support of that goal, modeling of singles and coincident gamma-ray spectra that would result from various chemical separation strategies has been performed. These simulated spectra have identified likely instances of spectral interference and have provided an estimate of the time window available for the detection of radionuclides following various chemical separation schemes. A description of results to date is presented here, demonstrating the utility of this approach for improved processing and analysis of fission product samples.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Douglas, J. Friese, L. Greenwood, O. Farmer, M. Thomas, T. Maiti, E. Finn, S. Garofoli, P. Gassman, M. Huff, S. Schulte, S. Smith, K. Thomas, and P. Bachelor

Abstract  

Quantitative measurement of fission and activation products resulting from neutron irradiation of fissile materials is of interest for applications in environmental monitoring, nuclear waste management, and national security. Based on established separation processes involving co-precipitation, solvent extraction, and ion-exchange and extraction chromatography, we have optimized a proposed sequence of separation steps to allow for the timely quantification of analytes of interest. We have recently evaluated this scheme using an irradiated sample to examine the adequacy of separations for measurement of desired analytes by gamma spectrometry. Here we present the radiochemical separations utilized and the yields and purity obtained.

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