Hanford Tank 241-S-112 Residual Waste Composition and Leach Test Data

Abstract

SummaryAs directed by Congress, the U.S. Department of Energy (DOE) established the Office of River Protection in 1998 to manage DOE's largest, most complex environmental cleanup project -retrieval of radioactive waste from Hanford Site tanks for treatment and eventual disposal. Sixty percent by volume of the nation's high-level radioactive waste is stored at the Hanford Site in aging, deteriorating tanks. If not cleaned up, this waste is a threat to the nearby Columbia River and the Pacific Northwest.CH2M HILL Hanford Group, Inc. is the DOE Office of River Protection's prime contractor responsible for the storage, retrieval, and disposal of Hanford Site tank waste. As part of this effort, CH2M HILL Hanford Group, Inc. contracted with Pacific Northwest National Laboratory (PNNL) to conduct testing for selected key contaminants present in residual waste remaining in the single-shell tank 241-S-112 (S-112).This report presents the results of laboratory characterization, testing, and analysis of two samples (designated 20406 and 20407) of residual waste collected from tank S-112 after final waste retrieval. These studies were completed to characterize the residual waste and assess the leachability of contaminants from the solids. This is the first report from this PNNL project to describe the composition and leach test data for residual waste from a salt cake tank. All previous PNNL reports describing contaminant release models, and characterization and testing results for residual waste in single-shell tanks were based on samples from sludge tanks. iv important component of this encrustation. The SEM/EDS analysis also revealed the presence of Fe oxides, a Ca-Cr-O phase, a Pb-Cl±O phase, and possibly one or more silicate phases, but particles with these compositions were very rare in the tank S-112 residual waste.Results of the Tier 1 analysis of the bulk composition of tank S-112 samples indicate that Al is the largest, single metal component of the waste (7.1 to 8.4 wt% for the two samples). Other major metal components (Na, Fe, Cr, and Si) occurred at lower concentrations, ranging from 4.7 to 5.2%, 0.21 to 0.24%, 0.17 to 0.18%, and 0.10 to 0.14%, respectively, for the two samples. Based on these results and assuming Al occurs primarily as gibbsite, this Al phase would account for 21 to 24 wt% of the residual waste. The residual waste compositions determined in this study were generally consistent with those determined by the 222-S Laboratory, except for the concentrations determined for Al. 3 dilution (Le Chatelier's principle). For Ca, researchers determined that nearly all Ca in the extracts cameThe average Al concentration determined from the 222-S Laboratory results was 29.1 wt% (dry wt basis). If all Al occurred as gibbsite, this would account for 84% of the mass of the residual waste. This result is more consistent with PNNL's XRD and SEM/EDS results compared to those from the bulk composition analyses. Based on these comparisons, PNNL's Al concentrations for the unleached (as received) bulk solid appear t...

Contaminant Release Data Package for Residual Waste in Single-Shell Hanford Tanks

“…Concentration determined by the 222-S Laboratory are generally similar to those in Cantrell et al (2007a) for most analytical methods (including inductively coupled plasma-mass spectrometry [ICP-MS], ion chromatography [IC], alpha energy analysis [AEA], gamma energy analysis, technetium-99, and percentage water). The differences in the measured concentrations for selected analytes between those reported by the 222-S Laboratory and Cantrell et al (2007a) may be due to a variety of factors, primarily sample heterogeneity and the use of different extraction/digestion techniques by the two laboratories. See Cantrell et al (2007a) for more details.…”

“…The major compositional features of the C-103 residual waste are discussed in this section. Detailed chemical composition data for residual waste from tank C-103 are presented in Cantrell et al (2007a). Figure 2.3 shows the average concentrations of the major metals in the C-103 residual waste based on acid digestion analyses of three samples (19845, 19849, and 19850).…”

“…Anions were determined from the total concentrations of the periodic replenishment water leaching tests. A detailed description of the leaching tests for C-103 residual waste may be found in Cantrell et al (2007a). It should be noted that anion quantification by these leaching tests may be not be complete if an anionic constituent, such as phosphate, is present in insoluble minerals.…”

Technology Evaluation for Conditioning of Hanford Tank Waste Using Solids Segregation and Size Reduction

“…Additionally, the report documented work performed at the Hanford Waste Tank Complex, Tank S-112 [132][133] , during a retrieval process occurring in 2007 that involved an inadvertent elutriation process. The particles remaining in the tank after the inadvertent elutriation were ~100 microns or larger.…”

Hanford Site Tank 241-C-108 Residual Waste Contaminant Release Models and Supporting Data

“…Previous work to characterize and develop release models has been completed for final residual waste collected from five SSTs: C-106 (Deutsch et al 2006(Deutsch et al , 2007a; C-202, C-203 (Deutsch et al 2007c); C-103 (Cantrell et al 2008a); and S-112 (Cantrell et al 2008b). With the exception of one salt cake tank (S-112), all previous work describing characterization results and contaminant release models for final tank residual waste in SSTs were based on samples from sludge tanks.…”