caa a22 4500 378927205 CHVBK 20180305123620.0 cr unu---uuuuu 161128e20041101xx s 000 0 eng 10.1524/ract.92.9.819.54991 doi (NATIONALLICENCE)gruyter-10.1524/ract.92.9.819.54991 Geochemically derived non-gaseous radionuclide source term for the Asse salt mine - assessment for the use of a Mg(OH)2-based backfill material [Elektronische Daten] [Volker Metz, W. Schüßler, B. Kienzler, Thomas Fanghänel] The Asse salt mine was used as a test site for radioactive waste disposal from 1967 to 1978. Low- and intermediate-level waste forms (LLW/ILW) were emplaced, containing a total radionuclide inventory of 3×1015Bq, estimated for reference date January 1, 2005. It is expected that MgCl2-rich brine will enter the emplacement rooms and react with the cemented waste products. Possible microbal degradation of organic waste components in MgCl2-rich brine could produce significant quantities of CO2, resulting in an acidification and consequently in an increase of element solubilities. Application of buffering backfill materials is discussed for closure of the mine. Selection of backfill materials is based on geochemical modeling taking into account the corrosion of the cemented LLW/ILW and degradation of organic waste components. In the present study the evolving geochemical milieu and respective solubilities of Am, Np, Pu, U, Th, Tc, Sr, Cs and I were modeled for each emplacement room. Laboratory experiments were undertaken to selectively verify the modeling predictions. Geochemical modeling leads to the conclusion that Portland cement, a Mg(OH)2-based material and crushed salt can be used in different combinations as backfill materials. According to the predictions Mg(OH)2-based backfill material controls the pH and concentration of dissolved inorganic carbon within ranges that are favorable with respect to actinide solubilities. A source term for radioelements and fission products is derived from a comparison of the respective solubilities and the radionuclide inventories. Calculated solubilities of Th, Pu and U are lower than their inventories. These are controlled by the thermodynamic solubility therefore. Maximum solution concentrations of all other elements are controlled by their inventory. © 2004 Oldenbourg Wissenschaftsverlag GmbH Laboratory techniques, experiments nationallicence Analytical chemistry nationallicence Inorganic chemistry nationallicence Metz Volker aut Schüßler W. aut Kienzler B. aut Fanghänel Thomas aut Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 92/9-11/2004(2004-11-01), 819-825 0033-8230 92:9-11/2004<819 2004 92 ract https://doi.org/10.1524/ract.92.9.819.54991 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/ract.92.9.819.54991 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Metz Volker aut NATIONALLICENCE 700 1- Schüßler W. aut NATIONALLICENCE 700 1- Kienzler B. aut NATIONALLICENCE 700 1- Fanghänel Thomas aut NATIONALLICENCE 773 0- Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 92/9-11/2004(2004-11-01), 819-825 0033-8230 92:9-11/2004<819 2004 92 ract CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter