The Fuel Cycle Facility of the EBR-II complex contains a shielded high-purity argon inert-atmosphere cell which has been in operation since August 1963. During this time, the 66 000 ft3 cell has been filled twice with argon and emptied once. Each fill was conducted by flushing the cell with approximately 100 000 standard ft3 of argon. This reduced the oxygen content to about 1% for the first fill and about 0.7% for the second fill. The gas purification system then further reduced the oxygen content of the cell gas. Continuous operation of the gas purification system can maintain an atmosphere with oxygen impurities of 8 ppm and water impurities of 5 ppm at a cell inleakage rate of 0.24 standard ft3/h of air while operating the cell at a negative pressure of 2 to 4 in. of water.