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ASSESSMENT OF BASIC MIGRATION PHENOMENA OF ACTINIDES: COMPILATION, VERIFICATION, DETERMINATION OF THERMODYNAMIC CONSTANTS AND SPECIATION IN NATURAL AQUIFER SYSTEMS

Objective

THE FIRST PART OF THE RESEARCH IS TO OBTAIN RELIABLE THERMODYNAMIC CONSTANTS OF HYDROLYSIS REACTION AND CARBONATE COMPLEXATION FOR ACTINIDES OF DIFFERENT OXIDATION STATES, WHOSE DATA ARE NOT WELL KNOWN OR KNOWN WITH LARGE UNCERTAINTIES. THIS CONCERNS AM, PU, NP, TH AND U IONS. THE SPECIES ASSUMED FOR THE EVALUATION OF THERMODYNAMIC DATA WILL BE VERIFIED WITH THE HELP OF SPECTROSCOPIC OR OTHER METHODS.
THE SECOND PART OF THE PROGRAMME AIMS AT THE SPECIATION OF ACTINIDES IN VARIOUS AQUIFER SYSTEMS. THE CONDITIONS WOULD BE THOSE OF THE GORLEBEN AQUIFERS AS A MIRAGE REFERENCE SITE. THE ELEMENTS TO BE STUDIED ARE NP, PU AND AM. THE SPECIATION WILL BE CARRIED OUT USING LASER-INDUCED PHOTOACOUSTIC SPECTROSCOPY (LPAS) WITH THE HELP OF ULTRAFILTRATION AND ULTRACENTRIFUGATION. THE INDIRECT CHEMICAL SPECIATION WILL BE INCLUDED FOR EXTREMELY LOW CONCENTRATIONS: < 10-8 MOLAR. A NEW SPECTROSCOPIC METHOD USING LASER-INDUCED FLUORESCENCE (LFS) WILL BE TESTED FOR ACTINIDES OF TRI- AND HEXAVALENT STATE WITH AN EXPECTED SPECIATION SENSITIVITY UP TO 10-12 MOL/L.

1. COMPILATION, VERIFICATION, DETERMINATION OF THERMODYNAMIC CONSTANTS OF HYDROLYSIS REACTION AND CARBONATE COMPLEXATION.
- CRITICAL ASSESSMENT AND COMPILATION OF THERMODYNAMIC DATA OF AN(III), AN(IV), AN(V) AND AN(VI)
- EXPERIMENTAL DETERMINATION AND VERIFICATION OF UNCERTAIN THERMODYNAMIC DATA
- VERIFICATION OF SPECIES ASSUMED FOR THE EVALUATION OF THERMODYNAMIC DATA

2. SPECIATION OF ACTINIDES IN NATURAL AQUIFER SYSTEMS FROM THE MIRAGE REFERENCE SITE (E.G. GORLEBEN)
- SPECIATION UNDER VARIOUS GEOCHEMICAL CONDITIONS OF DIFFERENT AQUIFERS
- COMPARISON OF EXPERIMENTAL SPECIATION WITH THEORETICAL SPECIATION BASED ON THERMODYNAMIC DATA
- DEVELOPMENT OF A NEW SPECTROSCOPIC METHOD.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

TECHNICAL UNIVERSITY OF MUNICH
Address
21,Alte Akademie 16
85350 Freising
Germany