Integrated Disposal Facility FY2011 Glass Testing Summary Report

Abstract

Executive SummaryPacific Northwest National Laboratory was contracted by Washington River Protection Solutions, LLC to provide the technical basis for estimating radionuclide release from the engineered portion of the disposal facility (e.g., source term). Vitrifying the low-activity waste at Hanford is expected to generate over 1.6 × 10 5 m 3 of glass (Puigh 1999). The volume of immobilized low-activity waste (ILAW) at Hanford is the largest in the DOE complex and is one of the largest inventories (approximately 0.89 × 10 18 Bq total activity) of long-lived radionuclides, principally 99 Tc (t 1/2 = 2.1 × 10 5 ), planned for disposal in a low-level waste (LLW) facility. Before the ILAW can be disposed, DOE must conduct a performance assessement (PA) for the Integrated Disposal Facility (IDF) that describes the long-term impacts of the disposal facility on public health and environmental resources. As part of the ILAW glass testing program PNNL is implementing a strategy, consisting of experimentation and modeling, in order to provide the technical basis for estimating radionuclide release from the glass waste form in support of future IDF PAs. The purpose of this report is to summarize the progress made in fiscal year (FY) 2010 toward implementing the strategy with the goal of developing an understanding of the long-term corrosion behavior of low-activity waste glasses.The emphasis in FY2010 was the completing an evaluation of the most sensitive kinetic rate law parameters used to predict glass weathering, documented in Bacon and Pierce (2010), and transitioning from the use of the Subsurface Transport Over Reactive Multi-phases to Subsurface Transport Over Multiple Phases computer code for near-field calculations. The FY2010 activities also consisted of developing a Monte Carlo and Geochemical Modeling framework that links glass composition to alteration phase formation by 1) determining the structure of unreacted and reacted glasses for use as input information into Monte Carlo calculations, 2) compiling the solution data and alteration phases identified from accelerated weathering tests conducted with ILAW glass by PNNL and Viteous State Laboratory/Catholic University of America as well as other literature sources for use in geochemical modeling calculations, and 3) conducting several initial calculations on glasses that contain the four major components of ILAW

Candidate Low-Temperature Glass Waste Forms for Technetium-99 Recovered from Hanford Effluent Management Facility Evaporator Concentrate

“…To show the effects of dissolution of the different glasses, modeling was performed on the candidate glasses presented in Table 3. The approach used was similar to the modeling reported by Pacific Northwest National Laboratory for Immobilized Low Activity Waste [Pierce 2011]. The accuracy of these model results is limited by the quality of experimental data that currently exists for the key species in these novel glass waste forms.…”

Technetium Immobilization Forms Literature Survey

“…There have been extensive studies of glass corrosion spanning more than three decades (Barkatt et al 1986;Hench et al 1986;Bunker et al 1988;Casey and Bunker 1990;Werme et al 1990;Bourcier 1991Bourcier , 1994Vernaz and Dussossoy 1992;Cunnane et al 1994a,b;McGrail et al 1997;Strachan and Croak 2000;Vernaz et al 2001;Icenhower et al 2004;Van Iseghem et al 2004). The glass dissolution process can be divided into five stages (Pierce et al 2011) including 1. Initial diffusion or interdiffusion.…”