Evaluation of Gas Retention in Waste Simulants: Intermediate-Scale Column and Open-Channel-Depth Tests

Abstract

 gas density of the retained gas, kg/m 3  gf gas-free simulant density, kg/m 3  s dry density of the sediment particles, kg/m 3  w water density, kg/m 3  s undrained shear strength, Pa  avg average retained gas fraction  g retained gas fraction  init initial retained gas fraction  local local retained gas fraction

Morphology of Gas Release in Physical Simulants

“…Of particular concern was the method used to generate a given volume of gas within the test material. Testing of gas retention and release has used several approaches for gas generation:  addition of peroxide (e.g., Rassat et al 2013;Gauglitz et al 2013)  addition of water-reactive metal powders such as iron or magnesium (Gauglitz et al 2012;Powell et al 2014)  radiolysis of water and organics using an external high-dose radiation source (e.g., Gauglitz et al 1996)  nucleation and expansion of soluble gas under vacuum (e.g., Rassat and Gauglitz 1995)  hydrophobic particle captive bubble expansion (e.g., Crawford et al 2013) The gas generation approach selected for cold simulant gas-release testing was nucleation and expansion of soluble gas under vacuum. In addition, several confirmatory tests support cold simulant testing employed addition of peroxide.…”

“…The gas generation and release mechanisms selected for the main course of testing differ from those used in DSGREP companion studies (Rassat et al 2013;Powell et al 2014). For the majority of testing, gas nucleation is effected by application of vacuum as opposed to addition of hydrogen peroxide (or reactive metals), and gas release is effected by vibration as opposed to direct stirring or motion caused by a Rayleigh-Taylor instability.…”

Hydrogen Gas Retention and Release from WTP Vessels: Summary of Preliminary Studies

“…The clay was packaged as a dry powder in 50 lb bags, and used as-received (as-is). The expected moisture content is ≤2 wt% based on previous analyses (e.g., Powell et al 2014).…”

“…The Rassat et al (2003) correlation is similar to the new large-batch correlation for Test FG 23-02 stock and water-dilution samples. Further, Figure 5.4 shows a correlation presented in Gauglitz et al (2012a) and another derived (as shown in the plot) from data in Powell et al (2014). 1 Both of these correlations used the same grade of EPK kaolin and indicate higher shear strengths at a given solids content than the others shown in the figure.…”

“…observed that the geltime effect was significant for 90:10 M30:B simulant: the shear strengths of samples left undisturbed after remixing for ~1 hour were about 60 percent of the values for the same samples left undisturbed for ~18 hours. However, the effect of gel time on kaolin slurry shear strength is comparatively negligible for 1 Shear strength and dry solids content are given inTable 2.2 ofPowell et al (2014). The equivalent "as-is" solids content plotted inFigure 5.5 was back-calculated from the dry solids values using the measured moisture content of "about 1.85 wt% water" for stock kaolin that is also reported inPowell et al (page 2.5).…”