[en] Tank 9 was placed in service as a receiver for Purex HLW on July 19, 1955. Filling was essentially completed in December 1955, and this original complement of waste remained in the tank until December 1965, when most of the liquid was decanted to allow refilling. In July 1966, the remaining liquid and approximately 15 inches of sludge were removed using 3000 to 3500 psi water introduced through nozzles to mobilize the sludge. The tank was then used as a receiver and cooler for aged HLW solution concentrated by the tank farm evaporator; the resulting crystallized salt, covered with saturated solution, is now stored in this tank. Inspections have been made of the tank interior and annulus by direct observation and with a 40-ft optical periscope. Analytical samples have been taken of the sludge, supernate, vapor, and leaked material in the annulus. Top-to-bottom profiles of radiation and temperature have been obtained in the annulus and tank, respectively, and measurements have been made of roof deflection caused by salt adhering to roof-supported cooling coils. Leaked waste was discovered in the annulus pan in October 1957. During 1958-59, the annulus pan was flushed nine times with water in 2000-gallon batches, jetting the waste and flush water into the primary tank. However, waste leakage into the annulus continued. The maximum liquid depth reached in the annulus was about 12 inches. This was jetted out in 1961., but some leakage continued theeeafter as indicated by roddings. The roddings showed no standing liquid by August 1964, but some liquid may have been present undera salt crust. In March 1972, salt depth in the annulus was measured to be 8 to 10 in., and the bottom 3 in. was quite wet. The salt remains although most of the liquid has been removed