Membrane-Sorption Technology for Purification and Concentration of Low-Level Liquid Waste from Transport NPPs

The radionuclide composition of liquid waste going from transport nuclear power plants (TNPPs) to reprocessing is determined by ⁹⁰Sr, ¹³⁷Cs, ¹³⁴Cs, ⁶⁰Co, to a lesser extent ⁵⁴Mn, and others. In terms of their chemical composition, they are low-salt. The anionic composition is determined by ${\textrm{HCO}}_3^{-}$, ${\textrm{SO}}_4^{2\hbox{--} }$, and Cl^–. The proposed membrane-sorption technology employs a complex of membrane methods: micro-, ultra-, and hyperfiltration in addition to the previously developed ion-exchange and sorption purification. The equipment has passed preliminary, resource, and State tests on liquid wastes from TNPP prototypes. The purification efficiency reaches 10⁵ regardless of the physicochemical forms of the radionuclides (ionic, colloidal, molecular, etc.). The maximum salt content of the concentrate is 51.2 g/L with volumetric activity 3.6·10² kBq/L. For initial waste with a salt content of 500 mg/L, the concentration factor was approximately 100. The efficiency of the technology has been repeatedly tested on waste stored in bulk tankers of the Pacific Fleet. The waste was not only radioactive, but also chemical with a high content of harmful substances, such as petroleum products and heavy metals.