PCT Leach Tests of Hot Isostatically Pressed (HIPped) Zeolitic Concretes

Abstract

ABSTRACTThe logical place for the US Federal government to site a permanent repository for its massive accumulation of cold-war reprocessing radwaste would be at its primary cold-war nuclear device testing reservation, the Nevada Test Site(1). Regardless of whether it eventually chooses to implement that repository by drilling lateral “drifts” into consolidated rock (e.g. its proposed Yucca Mountain facility) or by augering moderately-deep boreholes into unwelded alluvium beds (e.g. the “Greater Confinement Disposal (GCD) repository implemented at Frenchman Flats in 1984 (2), zeolitic hydroceramic materials would be more stable than would glasses. The thermodynamic rationale for this is that in such regions, soil solutions and soil gasses both tend to “weather” buried natural glasses to zeolitic materials(3). It has also been demonstrated that the same type of phases form when properly designed cementitious “grouts” are cured under mild hydrothermal conditions(4,5) - precisely those conditions assumed by DOE's repository modelers for “failed” (i.e. flooded) repositories and under which radwaste-type glasses rapidly decompose to form crystalline zeolitic phases(6,7).