HR: 15:05h
AN: H23H-06 INVITED     [Abstracts]
TI: Colloid Facilitated Transport of Plutonium in Fractured Volcanic Tuff
AU: * Kersting, A B
EM: Kersting@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Zhao, P
EM: Zhao1@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Walensky, J R
EM: walensky2@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Roberts, S K
EM: Roberts28@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Johnson, M R
EM: Johnson306@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Zavarin, M
EM: Zavarin1@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AU: Ramon, E C
EM: Ramon1@llnl.gov
AF: Lawrence Livermore National Lab, PO Box 808, Livermore, CA 94550
AB: The transport of low-solubility radionuclides in a colloidal- or colloidal bound state is frequently suspected or observed. Groundwater contaminated with radionuclides associated with underground nuclear tests was collected from several different well locations at the Nevada Test Site (NTS). In each case, the low-levels of plutonium detected in the groundwater were overwhelmingly (>95percent) associated with the colloidal and not the dissolved fraction of the groundwater. The colloidal fractions consisted of secondary minerals such as clays and zeolites. To better understand the mechanisms controlling the potential colloidal transport of plutonium, colloid-facilitated fracture flow laboratory experiments are being conducted. Pseudocolloids consisting of Pu(IV) sorbed to clinoptilolite were combined with a radionuclide solution cocktail consisting of Np, U, Cs, Sr, Sm and 3H and Re (analog to Tc) tracers in NTS-type synthetic groundwater (4.5mM NaHCO3-). The cocktail was injected into a smooth fracture in a volcanic tuff rock core from the NTS and the effluent analyzed. Autoradiography and secondary ion mass spectrometry will be used to understand the mineral -colloid-radionuclide interactions in the fracture volcanic tuff.
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting