The effects of heating and dilution on the rheological and physical properties of Tank 241-SY-101 waste

Abstract

Of the 177 high-level waste underground storage tanks at the Hanford Site, 25 have been identified as being potentially capable of generating and releasing flammable gas. Tank 241-SY-101 has exhibited periodic releases of gas, and in some cases the gas released has exceeded the lower flammable gas limit. The components of the released gas from Tank 241-SY-101 are hydrogen, nitrous oxide, nitrogen, ammonia, carbon monoxide, and methane. A mitigation strategy that may effectively reduce the retention and release of these gases and the release of flammable gases is dilution coupled with eating of the tank wastes. The purpose of this work was to determine changes in rheological and physical properties caused by heating and dilution of actual 241-SY-101 waste. In May and December 1991, following periodic gas releases, samples of the waste in Tank 241-SY-101 were obtained. Current work quantified the effects of heating coupled with NaOH dilution of a combination of waste samples from Tank 241-SY-101 characteristic of a non-convective layer. The experimental approach and results of this heating and dilution study on Tank 241-SY-101 waste samples are described in Sections 2 and 3, respectively. In Section 3.1, a discussion of the rheological properties of the waste as a more » function of shearing forces, volume percent dilution, and temperature is presented. In Section 3.2, the physical properties of the waste dilutions are described, including the densities of the slurry, filtered solids, and filtrate; the settling behavior; and the percent filtered solids in the composite sample and each of the composite dilutions. A brief discussion of the results and uncertainties is given is Section 3.3. The conclusions of this investigation are reported in Section 4. « less