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Portions of this AbstractThis report presents the results of the operation of the void fraction instrument (VFI) and ball rheometer in Hanford Tank 241-SY-103. The two instruments were deployed through risers 17C and 22A in July and August 1995 to gather data on the gas content and rheology of the waste. The results indicate that the nonconvective sludge layer contains up to 12% void and an apparent viscosity of 104 to 105 CP with a yield strength less than 210 Pa. The convective layer measured zero void and had no measurable yield strength. Its average viscosity was about 45 cP, and the density was less than 1.5 g/cc. The average void fraction was 0.047 f 0.015 at riser 17C and 0.091 f 0.015 at riser 22A. The stored gas volume based on these void fraction measurements is 2 13 f 42 m3 at 1 atmosphere.... lll SummaryHanford waste Tank 241-SY-103 is filled to about two-thirds capacity, and the current waste level is about 6.9 m. The waste consists of a relatively thin, incomplete crust layer floating on a convective layer about 3.6 m thick with a 3.3-m nonconvective sludge layer on the bottom. This tank has experienced gas release events (GREs) at irregular intervals of roughly three months since its last fill in 1988. Though these events are much smaller than those of its neighbor, Tank 241-SY-101, there is a need to obtain measurements of the void fraction profile and waste rheology in order to estimate the stored gas volume and the amount that could potentially be released.The ball rheometer was deployed July 14 and August 8, 1995, and the void fraction instrument (VFI) on July 19 and August 18, 1995, to supply this information. Each instrument was deployed in risers 17C and 22A, which are located in the southeast and northwest quadrants at 8.5 m and 6.1 m from tank center, respectively. Because riser 17C is not vertical, the ball rheometer cable rubbed on the riser lip, requiring a load cell of relatively low resolution.The rheological properties of the convective layer were uniform and characterized by a low viscosity (about 45 cP), no yield strength (e 2 Pa), zero void fraction, and a density of about 1 . 5 gkc. The nonconvective sludge layer had a yield strength of less then 2 1 0 Pa and an apparent viscosity of 104 to 105 cP. The rheology of the sludge varied widely with depth and was very sensitive to shear history, more so in riser 22A than 17C. The ball rheometer was not able to penetrate a heavier heel layer, about 120 cm thick, on the tank bottom.The data also revealed much different void fractions in the nonconvective layers in each riser. The local void ranged up to 12.5% in the lower portion of the sludge layer. The average void fraction at 17C was 0.047 k 0.015; it was 0.091 4 0.015 at riser 22A. This difference may be attributed to differences in GRE history at the two locations. The waste in the vicinity of 17C may have participated in more of the recent rollover events, while the waste around riser 22A may have remained relatively undisturbed. Assuming approximately equal portions of the tank a...

Testing SummaryThe U.S. Department of Energy (DOE) Office of River Protection's Waste Treatment and Immobilization Plant (WTP) will process and treat radioactive waste stored in tanks at the Hanford Site. The waste treatment process in the pretreatment facility will mix both Newtonian and non-Newtonian slurries in large process tanks. Process vessels mixing non-Newtonian slurries will use pulse jet mixers (PJMs), air sparging, and recirculation pumps. An anti-foam agent (AFA) will be added to the process streams to prevent surface foaming but may also increase gas holdup and retention within the slurry.Some gas retention tests that were carried out in nonprototypic systems-bubble columns and impeller-mixed vessels-indicated trends that posed process and flammable-gas concerns . Both types of nonprototypic results indicated that the presence of AFA in a chemical simulant of Hanford Tank 241-AZ-101 high-level waste (HLW) might increase gas retention by a factor of 10 or more over that in clay without AFA, the simulant on which WTP design studies were based (see Section 1.2). In addition, the increase over clay holdup was greater at lower simulant yield stress, implying that the 30-Pa simulant results, which had been used for WTP design, might not bound gas retention.The work described in this report addresses gas retention and release in simulants with AFA through prototypic testing and analytical studies. This test program was established to determine whether the AFA has as strong an effect in a large-scale prototypic mixing system as it did in the small-scale nonprototypic tests. Gas holdup and release tests were conducted in a 1/4-scale replica of the lag storage vessel operated in the Pacific Northwest National Laboratory (PNNL) Applied Process Engineering Laboratory using a kaolin/bentonite clay and an AZ-101 chemical simulant with non-Newtonian rheological properties representative of actual waste slurries. Additional tests were performed in a smallscale mixing vessel in the PNNL Physical Sciences Building using liquids and slurries representing major components of typical WTP waste streams to address the fact that simulants delivered to the WTP will come from other tanks in addition to 241-AZ-101. Analytical studies were directed at discovering how the effect of AFA might depend on gas composition, and a model was developed for predicting the effect of AFA on gas retention and release in the WTP, including the effects of mass transfer to the sparge air.The prototypic gas retention and release tests performed in this test program indicate that gas holdup with AZ-101 simulant with AFA is higher than it is in clay, but not to the extent that initially raised WTP design concerns. In addition, the trend to a higher increase in holdup with decreasing simulant yield stress was not seen in the prototypic system. The work at PNNL was part of a larger program that included tests conducted at Savannah River National Laboratory (SRNL) that is being reported separately. SRNL conducted gas holdup tests in a small-scale m...

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