Research Program to Investigate the Fundamental Chemistry of Technetium

Research Progress and Implications Portions of two Tc glasses, LBNL-118 (Hanford AP-101 tank formulation) and LBNL-121 (higher organic content Hanford AN-107 tank formulation), were placed in vapor hydration test (VHT) stainless steel pressure vessels and exposed to a hydrous atmosphere at 238 C for 24.9 days. After being removed from the vessels, complete sample alteration is clearly visible for both samples. X-ray absorption spectra were then collected on these samples to characterize the Tc speciation within the alteration layers. The X-ray fluorescence signal was significantly improved for both VHT samples compared with that collected for the corresponding unaltered glasses, so much so that X ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data could be collected for each VHT sample. This signal improvement for the VHT samples indicates that a significant amount of the Tc in the original glasses has migrated closer to the VHT sample surface; this surface enrichment results in a stronger Tc X ray signal than is the case for the more homogeneously distributed Tc in the original glasses