Geochemical engineering of low level radioactive waste in cementitious environments

Significantly reduced release of radionuclides from low level radioactive waste disposal facilities may be achieved by passively engineering the geochemical environment in and immediately adjacent to shallow land burial sites. Mineral growth and adsorption onto cementitious waste forms, casks, and backfills is calculated to minimize the transport of 234,238U, 241Pu, 241Am, 232Th, 59,63Ni and 14C. Reductive adsorption of Tc to Fe(II)-rich minerals may be engineered by emplacing a fine-grained mafic (basalt, serpentinite, scrap iron) blanket of aggregate below and around the LLRW repository. 90Sr and 137Cs transport into the biosphere may also be retarded due to adsorption on cementitious material, through scavenging by the Fe-oxyhydroxide weathering products of the mafic blanket, and by dilution.