METHOD FOR PRE-TREATMENT OF HIGH-ACTIVITY CONCENTRATE TO BE HARDENED BY VITRIFICATION Russian patent published in 2002 - IPC

FIELD: recovery of radioactive wastes produced at spent nuclear fuel recovery factories. SUBSTANCE: method includes preparation of high-activity concentrate from mixture of radioactive solutions by way of thermal evaporation and delivery of concentrate obtained to vitrification kiln. Source concentrate is doped with concentrated sodium nitrate bottoms produced in evaporation of medium-activity solutions and/or sodium hydroxide solution from liquid radioactive waste storage tanks. Mixture prepared in this way is treated with boric acid and/or sodium tetraborate, and/or optophosphoric acid. EFFECT: enhanced sodium nitrate content, reduced nitric acid concentration, preventing crystallization of finely dispersed salts in concentrates. 5 ex