US 12,456,558 B2
Method for concentrating liquid radioactive waste
Boris Jakovlevich Zilberman, Saint-Petersburg (RU); Dmitry Viktorovich Ryabkov, Saint-Petersburg (RU); Nadezhda Evgenievna Mishina, Saint-Petersburg (RU); Nikolay Alekseevich Dedov, Saint-Petersburg (RU); Artem Iurevich Nikolaev, Saint-Petersburg (RU); Ekaterina Viktorovna Andreeva, Saint-Petersburg (RU); Irina Vladimirovna Blazheva, Moscow (RU); Konstantin Viktorovich Kostromin, Yekaterinburg (RU); and Andrei Yur'evich Shadrin, Moscow (RU)
Assigned to STATE ATOMIC ENERGY CORPORATION “ROSATOM” ON BEHALF OF THE RUSSIAN FEDERATION, Moscow (RU)
Appl. No. 17/757,094
Filed by STATE ATOMIC ENERGY CORPORATION “ROSATOM” ON BEHALF OF THE RUSSIAN FEDERATION, Moscow (RU)
PCT Filed Oct. 1, 2020, PCT No. PCT/RU2020/000510
§ 371(c)(1), (2) Date Jun. 9, 2022,
PCT Pub. No. WO2021/118402, PCT Pub. Date Jun. 17, 2021.
Claims priority of application No. 2019141171 (RU), filed on Dec. 11, 2019.
Prior Publication US 2023/0005633 A1, Jan. 5, 2023
Int. Cl. B01D 1/00 (2006.01); G21F 9/08 (2006.01)
CPC G21F 9/08 (2013.01) [B01D 1/0094 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A method for concentrating liquid radioactive waste resulted from extraction reprocessing of a burnt-up nuclear fuel of a nuclear power station, comprising:
performing a partial decomposition of nitric acid in a course of continuous evaporation while a solution containing a reducing agent is fed into a bottom part of a circulation-type evaporator,
wherein a mixture of formaldehyde and formic acid is used as the reducing agent,
wherein the method is conducted with aging the solution in the bottom part of the evaporator,
wherein a water solution of a mixture of formaldehyde and formic acid or a solution of formic acid is fed as the reducing agent in 3-5 hours after the start of the method using the mixture of formaldehyde and formic acid, and
wherein, when starting the method, the solution of formaldehyde and formic acid is used with a maximum formaldehyde content of 6.5 moles/L but not less than 0.65 moles/L, and a missing part thereof is replaced with formic acid in a quantity of 2.2-2.7 moles of formic acid instead of 1 mole of formaldehyde.