The presence of gas bubbles is expected to affect the rheology of the sludge, but essentially no literature data are available to assess the effect of bubbles. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The retention and episodic release of flammable gases are critical safety concerns for double-shell tanks that contain waste slurries. International Nuclear Information System (INIS) Gas distribution effects on waste properties: Viscosities of bubbly slurries