Spectroscopic study on the mononuclear hydrolysis species of Pu(VI) under oxidation conditions

Progress of energy-related radiochemistry and radionuclide production in the Republic of Korea

The field of radiochemistry in the Republic of Korea has expanded greatly over the last three decades to meet the rapid growth of technological demands in various areas such as nuclear energy and nuclear technologies for human health and environmental protection. Major research activities, which were initially centered at the Korea Atomic Energy Research Institute (KAERI), have gradually spread to major universities and the commercial sector. In this review, progress and recent research trends in nuclear and radiochemistry in Korea are summarized. The main research outcomes achieved by KAERI scientists are highlighted, with emphasis on basic actinide chemistry in nuclear fuel cycles, the radioanalytical chemistry of various radionuclides from radioactive waste and the environment, and medical radionuclide production. In addition, recent efforts to promote radiochemical education and future perspectives are briefly outlined.

Plutonium interaction studies with the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99: changes in the plutonium speciation by solvent extractions

Since plutonium could be released from nuclear waste disposal sites, the exploration of the complex interaction processes between plutonium and bacteria is necessary for an improved understanding of the fate of plutonium in the vicinity of such a nuclear waste disposal site. In this basic study, the interaction of plutonium with cells of the bacterium, Sporomusa sp. MT-2.99, isolated from Mont Terri Opalinus Clay, was investigated anaerobically (in 0.1 M NaClO₄) with or without adding Na-pyruvate as an electron donor. The cells displayed a strong pH-dependent affinity for Pu. In the absence of Na-pyruvate, a strong enrichment of stable Pu(V) in the supernatants was discovered, whereas Pu(IV) polymers dominated the Pu oxidation state distribution on the biomass at pH 6.1. A pH-dependent enrichment of the lower Pu oxidation states (e.g., Pu(III) at pH 6.1 which is considered to be more mobile than Pu(IV) formed at pH 4) was observed in the presence of up to 10 mM Na-pyruvate. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g., biosorption and bioreduction.

Mass spectrometric characterization and quantification of Pu(VI) hydrolysis products

In the present work the first direct measurement of hydrolysis products of Pu(VI) was achieved by means of nano-electrospray ionization time-of-flight mass-spectrometry. The results indicate that monomeric PuO2(OH) + and dimeric (PuO2)2(OH) 2 2+ species are present in solution. A trimeric species does not appear within the detection limit of the experiment, in contrast to U(VI) hydrolysis. The relative abundances of the Pu(VI) hydrolysis species in the ESI mass spectra are in good agreement with the published formation constants.