AVS 59th Annual International Symposium and Exhibition
    Actinides and Rare Earths Focus Topic Tuesday Sessions
       Session AC+EN-TuM

Paper AC+EN-TuM9
Actinide Subsurface Chemistry in Waste Isolated Pilot Plant, Recent Development

Tuesday, October 30, 2012, 10:40 am, Room 006

Session: Energetic Materials Issues for Nuclear Power: Fuels, Corrosion and Waste Disposal
Presenter: M. Borkowski, Los Alamos National Laboratory
Authors: M. Borkowski, Los Alamos National Laboratory
J.-F. Lucchini, Los Alamos National Laboratory
M.K. Richmann, Los Alamos National Laboratory
D.T. Reed, Los Alamos National Laboratory
Correspondent: Click to Email
Waste Isolation Pilot Plant (WIPP) is designed to permanently dispose radioactive waste generated by the US defense program. Waste is placed in a salt bed 2150 feet below the ground level. During the regulatory time repository may be filled with brine and interaction of brine components with actinide is objective of the Actinide Chemistry Repository Science Program. One of the brine components is borate (up to ~160 mM), present in the brine by the dissolution of Borax mineral. Borate chemistry especially in basic media is still unknown and in this study the interesting borate speciation in the basic media is presented. Recently it was reported that neodymium, analog for trivalent actinides, is complexed by tetraborate ion with log K ~4 and that plutonium forms a stronger complexes than that of neodymium. Also neptunium (V) forms complexes with borate and spectrophotometric evidence will be presented. Further investigations of borate chemistry and borate complexing properties are also discussed. Complexation power of different polyborate forms may be different. Some are able to form a covalent bond but other forms can only atract cation by a weak electrostatic interaction. Borate provides a wide range of pH buffering capacity from 6 to 12.