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MS: Fachverband Massenspektrometrie

MS 1: Laser-Resonanzionisation, REMPI und MALDI

MS 1.2: Hauptvortrag

Montag, 8. März 2010, 14:30–15:00, F 428

ESI-MS for nuclear safety assessment: Polymerization of plutonium — •Clemens Walther — Institut für Nukleare Entsorgung, Karlsruher Institut für Technologie, Postfach 3640 D-76021 Karlsruhe, Germany

The safety assessment of prospective deep geological nuclear waste disposal sites such as Gorleben (or the research salt mine Asse) requires detailed knowledge of aqueous chemistry of radionuclides. Water intrusion into the repository may lead to leaching processes and migration of radionuclides. Among these the long lived actinides 241 americium and 239 plutonium (half lifes 430y and 24000y, respectively) are of particular relevance. Since man made containers cannot be expected to stand > 250000 y (10 half lifes) immobilizing processes (such as sorption or incorporation into the host matrix) and mobilizing processes (volatility or colloid mediated transport) must be understood on a molecular level. Repository conditions must be chosen such as to favor immobilizing conditions over geological timescales. In the present work polymerization processes of tetravalent actinides (the most prominent example being 239Pu) are investigated by high resolution nano-electrospray mass spectrometry. Polymerization may lead to formation of colloids and subsequent efficient transport as recently demonstrated in the case of former Nevada nuclear weapons test sites and a Russian reprocessing plant. Hence, conditions must be chosen to inhibit these reaction path ways.