Abstract

The article presents the results of the development of a modular laboratory unit for the purification of radioactive water based on the basic principles of plasma chemical technologies at the South Ukraine Nuclear Power Plant. The main technical characteristics of the unit and the algorithm for controlling the radioactive water purification process are given. Preliminary work they been carried out to develop the main algorithms for the purification of radioactive water at the Chernobyl Nuclear Power Plant. We obtained the most significant results using the third algorithm for the purification of radioactive water. The results of the third algorithm show that the sorption of radionuclides by a complex sorbent based on copper ferrocyanide, iron nanoparticles and coagulants with preliminary preparation of radioactive water by plasma electrolysis for 60 minutes and subsequent single- and two-stage treatment by plasma electrolysis in combination with sorbents for 30-45 minutes. Stirring in a magnetic mixer and the use of Zb series sorbents resulted in the removal of 137Cs ions to an activity of 2.48 Bq/dm3 , which is 1.3E7 times lower than the cesium activity (3.2E7 Bq/dm3 ) of the initial radioactive water. PK series - removal of 137Cs ions to an activity of 129 Bq/dm3 , which is 2.5E5 times lower than the activity of cesium (3.2E7 Bq/dm3 ). Removal of 90Sr ions to an activity of 6.85E2 Bq/dm3 under the above-mentioned sorption conditions using PK series sorbents, which is 17.1E3 times lower than the activity of strontium (4.9E6 Bq/dm3 ) in the initial radioactive water. The use of complex sorbents of the Zb and PK series and the above-mentioned conditions ensured the complete removal of 154Eu and 241Am ions. The cycle of experiments on the purification of radioactive water shows the effect of plasma electrolysis on the destruction of organic radicals, which contributes to the additional removal of 137Cs and 90Sr ions and their sorption. The result obtained it’s probably explained by the fact that the sorption of 137Cs ions and transuranic radionuclides on ferrocyanides and iron nanoparticles occurs in the presence of hydroxyl groups. Because of cleaning the radioactive liquid waste at the South Ukraine Nuclear Power Plant using sorbents and a plasma discharge unit, it was possible to achieve complete removal of 54Mn, while the activity of 60Co and 134Cs decreased by two orders of magnitude and the activity of 137Cs decreased by one order of magnitude. After cleaning, the initial total activity of liquid radioactive waste decreased by 10% from the initial activity. This indicates the effectiveness of the method and the further prospects for its research and application. As for chemical indicators, permanganate oxidisability decreased by 7.4 times, and the content of ions determined became minimal. 

Keywords

nuclear power, radioactive waste, environmental safety, combined plasmachemical method, modularity, laboratory facility, radioactive waste treatment