Research on obtaining gadolinium oxide from waste technologies for processing of uranium-gadolinium containing materials

One of the activities of the Uranium production of JSC “UMP” is the processing of hard-to-open uranium-gadolinium-containing scraps. When processing materials of this type, after their dissolution, the gadolinium fluoride precipitation operation is carried out with the subsequent extraction purification of the obtained uranyl nitrate solutions. At the deposition stage, almost all the gadolinium contained in the scraps is transferred to the GdF3 precipitate and sent to the tailings dump as part of the solid waste. In order to determine the possibility of obtaining gadolinium oxide from waste processing of uran-gadolinium containing materials, exploratory studies were initiated. In the course of the work, various methods of obtaining gadolinium oxide were tested. A number of experiments were carried out to refine the modes of obtaining gadolinium oxide by the method of two-stage precipitation of oxalate. A technological scheme was developed, according to which a finished product was obtained, suitable for further use in the technology of obtaining uranium-gadolinium tablets of UMP JSC. The scheme consists of the following main operations: dissolution of gadolinium fluoride in a solution of aluminum nitrate, precipitation of gadolinium oxalate, washing of gadolinium oxalate in the first stage of precipitation with a solution of nitric acid, conversion of oxalate to gadolinium hydroxide, dissolution of hydroxide in a solution of nitric acid, re-precipitation of gadolinium oxalate, calcination to gadolinium oxide.

Studying the treatment processes of soil samples from radionuclides

Object of research: Soil samples contaminated with radionuclides and processes for treatment of contaminated soil. The problem to be solved: Isolation of radionuclides from contaminated soil samples by extraction with weak solutions of acids and alkalis. Main scientific results: Treatment of soil samples contaminated with uranyl nitrate using extraction with weak solutions of nitric and hydrochloric acid, caustic sodium and subsequent washing of soil residues with distilled water is effective process and leads to a more than tenfold decrease in the content of uranium isotopes (U238, U235, U234 and U236) in the soil samples. At the same time, there is a decrease in the content of natural radionuclides (Na22, K40, Zn65, Sn113, Sn126) in the extracted soil samples. An increase in their content in the extract of the analyzed soil samples corresponds to a decrease in their content in the residue of the extracted soil samples. The analysis of the values of the decrease in the content of natural radionuclides in the soil contaminated with uranyl nitrate corresponds to the values of the decrease in their content in the identical soil, but not contaminated with uranium isotopes. The combined extraction with weak solutions of acids and alkalis leads to the enrichment of the soil with nitrates and chlorine-containing compounds. The area of practical use of the research results: Subdivisions of the Ministry of Emergency Situations and Chemical Troops specializing in the study of emergencies and natural disasters can use the results of these studies in the elimination of the consequences of global environmental disasters and incidents that pose a threat to the life of the civilian population and the personnel of paramilitary units. Innovative technological product: The proposed method for treatment of soil contaminated with radionuclides makes it possible to more than tenfold reduce their concentration in the soil. Scope of application of an innovative technological product: treatment of contaminated soil in areas affected by nuclear tests or accidents at nuclear power plants.

STUDY OF PURIFICATION PROCESSES OF SOIL CONTAMINATED WITH URANYL NITRATE

The extraction of uranyl nitrate contaminated soil with weak solutions of nitric and hydrochloric acid, caustic sodium and subsequent washing of soil residues with distilled water leads to a more than tenfold decrease in the content of uranium isotopes (U238, U235, U234, and U236) in the soil. At the same time, there is a decrease in the content of natural radionuclides (Na22, K40, Zn65, Sn113, Sn126) in the extracted soil samples. An increase in their content in the extract of the analyzed soil sample corresponds to a decrease in their content in the residue of the extracted soil sample. The combined extraction with weak solutions of these acids and alkalis leads to the enrichment of the soil with nitrates and chlorine-containing compounds of non-radioactive metals.

Speciation analysis the complexation of uranyl nitrate with tri-n-butyl phosphate in supercritical CO2

Uranyl nitrate complex with TBP in supercritical CO2 could form 1 : 1 and 1 : 2 species, and further generate 2 : 3 and 3 : 3 poly-core uranyl species.