The processing of low-level radioactive waste (LLRW) liquids that result from operation of nuclear power plants with reverse osmosis systems is not common practice. A demonstration facility is operating at Chalk River Laboratories (of Atomic Energy of Canada Limited), processing much of the LLRW liquids generated at the site from a multitude of radioactive facilities, ranging from isotope production through decontamination operations and including chemical laboratory drains. The reverse osmosis system comprises two treatment steps - spiral wound reverse osmosis followed by tubular reverse osmosis - to achieve an average volume reduction factor of 30:1 and a removal efficiency in excess of 99% for most radioactive and chemical species. The separation allows the clean effluent to be discharged without further treatment. The concentrated waste stream of 3 wt% total solids is further processed to generate a solid product. The typical lifetimes of the membranes have been nearly 4000 hours, and replacement was required based on increased pressure drops and irreversible loss of permeate flux. Four years of operating experience with the reverse osmosis system, to demonstrate its practicality and to observe and record its efficiency, maintenance requirements and effectiveness, have proven it to be viable for volume reduction and concentration of LLRW liquids generated from nuclear-power-plant operations.
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