RU1778076C - Method for producing isotope-pure protactinum-233 - Google Patents

Abstract

Usage: in the field of radioanalytical chemistry of actinide elements, in particular, to the development of methods for the isolation of high-purity radionuclides without a carrier according to the principle of isotope generators. SUBSTANCE: to obtain isotopically pure protactini - 233, the parent radionuclide neptunium-237 is sorbed onto an ion exchange column, and then the daughter Ra - 233 is washed out with mineral acid. Sorption is carried out on a strongly acidic cation exchanger from 0.1 mol / L nitric acid solution, and desorption of Ra by a solution of hydrofluoric acid until the tr-activity belonging to neptunium-237 appears in the eluate. Quantification and purity of the isolated Pj-233 is carried out radiometrically by D or g radiation and half-life. 1 tab.

Description

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The invention relates to the radioanalytical chemistry of actinide elements, in particular to the development of methods for the isolation of high-purity radionuclides without a carrier according to the principle of isotope generators.

The aim of the invention is to increase the degree of purity and specific activity of the isotope, reduce the time for its preparation and simplify the process by creating an isotope generator.

In order to obtain isotopically pure protactinium -233, the parent radionuclide neptunium-237 is adsorbed onto the ion exchange column, and then the daughter Ra-233 is repeatedly washed out with a small volume of mineral acid. Sorption is carried out on a strongly acidic cationine from a 0.1 mol / L nitric acid solution, and the desorption of Pn with a solution of 0-2.5 10 mol / L hydrofluoric acid at a tap speed of 03-10 mp / min to

by the appearance in the eluate of cr activity belonging to neptunium-237. The quantification and purity of the isolated Pj-233 is carried out radiometrically by / 3 or γ-radiation and half-life.

The table shows the results of studies on the effect of the concentration of hydrofluoric acid on the distribution coefficients of Np and Pa on the Dowex-50 x 8 cation exchanger and the volume of the eluent in which more than 80% of the protactini is washed out from a 0.4 x 6 cm column, as well as the content Np-237 in the Ra fraction and elution rate.

It follows from the table that, to wash out protactini, it is most expedient to use hydrofluoric acid solutions with a concentration of 1.010 -2.5.10 mol / L as an eluent since in such solutions the maximum difference in the distribution coefficients Np and

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about VI

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Ra, which makes it possible to repeatedly wash the latter in a minimum volume of eluent with a high specific activity and with a high degree of purity. Changing the elution rate in the range of 0.3-1 ml / min does not affect the yield and purity of the precipitated Ra and also ensures the expressness of the method.

Example. 600 mg of KU-2 air-dry cation exchanger with a grain size of 0.25-0.5 mm are placed in a 0.5 x 6 cm glass column and washed with 5 ml of a mol / L hydrofluoric acid solution. At the top of the column, 3.5 mg of Np is sorbed from 0.5 ml of NMO3 with a concentration of 0.1 mol / L. The total activity of the adsorbed neptun is 8.7-106 dec / 100.

To wash protactini -233, 3 ml of a mol / L HF solution was passed through the column at a rate of 0.5 ml / min. The column is then washed with 1-2 mol of H20 and the generator is left in water to accumulate and subsequently wash the protactini. Quantification of Ra-233 is carried out radiometrically by γ-radiation. The content of Ra was 90% of the accumulated. The absence of α-activity in the solution indicates a high degree of purification of protactini from neptuni (1-1 (g).

After repeatedly washing (100 times) the Ra-233 from the column at various time intervals (3, 7, 15, 30 days, etc.) for 12 months, the content of a-activity of Np-237 in the protactini fraction was

Hydrofluoric acid is the most suitable medium for storing and using protactini in various chemical operations, and the use of dilute HF solutions allows the use of glassware (columns, collectors).

The method for producing isotopically pure Ra-233 from its parent radionuclide Np-237 by the principle of an isotopic generator has a number of incomparable advantages:

ease of separation of Ra-233 by continuous washing, elution from a cation exchange column on which Np-237 is adsorbed, while the separation of Ra from an irradiated material involves a complex multi-stage process including precipitation, extraction and ion exchange;

a significant reduction in the time for the release of Ra from several hours (from irradiated Th) to several minutes by the proposed method;

using the generator, it is possible to isolate isotopically pure Ra-233 with a high degree of its purification (UMo6) from the parent radionuclide Np-237. When Ra-233 is obtained by irradiation with Th-232, Ra-231 may form, i.e. the isolation of isotope-pure Ra-233 in this

case is not guaranteed. In addition, when separating Ra from the irradiated material, it is necessary to separate it from Th, U and, most importantly, from the highly radioactive fission products that remain

in the Ra fraction, even after thorough cleaning;

leaching of Ra-233 from the generator is carried out repeatedly, as it accumulates, while from irradiated Th it is possible

Claims (1)

only a single selection of Ra. SUMMARY OF THE INVENTION A method for producing isotopically pure protactinium -233 by sorption of a starting product onto an ion exchanger followed by desorption of the target product with a mineral acid solution, characterized in that, in order to increase the degree of purity and specific activity of the isotope, shorten its preparation time and simplify of the process by creating an isotope generator, the sorption of the initial product of the radionuclide Np-237 is carried out on a strongly acidic cation exchanger from a nitric acid solution, the adsorption of Ra-233 is repeatedly carried out a solution of 1.0-25 mol / L hydrofluoric acid, eluting with 0.3-1.0 ml / min, until a-activity appears in the eluate. The distribution coefficients of Np and Ra between Dowex-50x8 cation exchanger and NF solutions of various concentrations and the leaching of Ra from a column of 0.4x6 cm