An In Tank Processing (ITP) technology was developed at the Savannah River Site to remove Cs-137 from high-level waste supernates. During the ITP process monosodium titanate and sodium tetraphenylborate (NaTPB) were added to the salt supernate to adsorb Sr-90/Pu-238 and precipitate Cs-137 as CsTPB, respectively. This process was demonstrated at the SRS in 1983. The demonstration produced 53,000 gallons of 2.5 weight per cent Cs rich precipitate containing TPB, which was later washed and diluted to 250,000 gallons. This material is currently stored in SRS tanks. The washed precipitate was to ultimately be disposed in borosilicate glass in the Defense Waste Processing Facility. Due to safety concerns the ITP process was abandoned in 1998, and new technologies are being researched for Cs-137 removal. In order to make space in the SRS Tank farm, the tank waste must be removed.