Knowledge of the oxidation state distribution of plutonium in natural waters is necessary in modeling its behavior in environmental systems. The redox speciation of plutonium is complicated by such effects as hydrolysis, complexation, disproportionation, solubility, and redox interchange reactions. The insolubility of Pu(OH)4 is often the limiting factor of the net solubility of plutonium in oxic natural waters where Pu(V)O
is the most stable oxidation state. Perturbations to the oxidation state speciation due to the complexation chemistry of the different oxidation states of plutonium and to the insolubility of plutonium(IV) in neutral aquatic systems are discussed. The merits and limitations of some chemical separation techniques used to study redox speciation of plutonium are presented, and recommendations made for obtaining reliable oxidation state distribution data.
Authors:G. Parkes, P. Barnes, E. Charsley, and G. Bond
This paper describes a new instrument for performing thermal analysis using microwaves both as a form of heating and as a
novel means of detecting thermally induced transformations in materials. Results are presented for a selection of processes
including decompositions, dehydrations and phase changes. The capability of the instrument to be coupled with ancillary techniques
such as EGA is also demonstrated.
Authors:E. Bond, S. Glover, D. Vieira, R. Rundberg, G. Belier, V. Meot, D. Hynek, Y. Jansen, J. Becker, and R. Macri
This paper describes the preparation of samples for an experiment to measure the cross-section for 235U(n,n′)235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of 235mU have been prepared for the calibration of the internal conversion electron detector that is used for the 235mU measurement. Two methods are described for the preparation of 235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha
recoil collection method. Thin, uniform samples of 235mU+235U were prepared for the experiment using electrodeposition.