Radioactive liquid wastes that are fully soluble or biologically dispersible in water may be discharged directly into the sanitary sewer system via a designated radiation sink drain. For research laboratories, the permissible limit of disposal by this means is restricted to fewer than 100 microcuries per day of H-3, and 30 microcuries per day of all other beta/gamma nuclides combined, averaged over a week. For nuclear medicine clinical laboratories, the permissible limit of disposal by this means is restricted to fewer than 100 microcuries per day of all beta/gamma nuclides combined. Alpha-emitting nuclides are not permitted to be disposed of by this means. Sinks must be appropriately designated and labeled (one sink per laboratory).
- Taking care to minimize splashing, pour the liquid waste directly into the drain with the water turned off.
- Follow immediately by flushing with copious quantities of water.
- Record the disposal on a sink log noting the date, isotope activity, and the initials of the person disposing of the material. If total activities greater than the weekly limits are generated, contact the Radiation Safety Office for special disposal directions.