Anaerobic digestion is a potentially attractive technology for volume reduction of low-level radioactive cellulosic wastes. A substantial fraction of the waste is converted to off-gas, and a relatively small volume of biologically stabilized sludge is produced. Process development work has been completed using a 75-L digester to verify rates and conversions obtained at the bench scale. Start-up and operating procedures have been developed, and effluent was generated for characterization and disposal studies. Three runs lasting 36, 90, and 423 d were made using batch and batch-fed conditions. Solids solubilization rates and gas production rates were approximately double the target values of 0.6 g of cellulose per L of reactor volume per d and 0.5 L of off-gas per L of reactor per d. Greater than 80% destruction of solids was obtained. Preliminary effluent characterization and disposal studies were completed. A simple dynamic process model has been constructed to aid in process design and for use in process monitoring and control of a large-scale digester. 5 refs., 20 figs., 3 tabs.