Examination of solids from 200 degree C hydrothermal tests with spent fuel

A series of hydrothermal experiments using fully-loaded spent light-water reactor (LWR) fuel have been initiated in the presence of reference groundwater (GR-4) at 200 degree C. The experiments are designed to investigate the geochemical interaction of spent fuel with the other constitutents of a nuclear waste repository in basalt. Three experiments have been closely investigated recently in an attempt to characterize the solids present. Of particular interest are secondary solid phases--those which formed during the experiment by reaction among constitutents. Of the three experiments, two contained only spent fuel and groundwater. These ran two and three months respectively. A third run contained reference Cohasset basalt and ran for six months. Solids were characterized using x-ray powder diffractometry and scanning electron microscopy (SEM) with energy-dispersive x-ray spectrometry (EDS)