Large storage tanks may require mixing to achieve homogeneity of contents for several reasons: prior to sampling for mass balance purposes, for blending in reagents, for suspending settled solids for removal, or for use as a feed tank to a process. At Oak Ridge National Laboratory, mixed waste evaporator concentrates are stored in ∼190-m3 (50 000-gal) horizontal tanks, about 3.7 m (12 ft) in diameter and 18 m (60 ft) in length. This tank configuration has the advantage of permitting transport by truck and therefore fabrication in the shop rather than in the field. A survey of the literature revealed no information on mixing large storage tanks with length-to-diameter ratios greater than 2. Jet mixing experiments were carried out in two model tanks: a 0.87-m3 (230-gal) Plexiglas tank that was ∼1/6 linear scale of the actual waste tanks and a 95-m3 (25 000-gal) tank that was about 2/3 linear scale of the actual waste tanks. Mixing times were measured by the use of a sodium chloride tracer and several cond...