Simultaneous radiochemical determination of plutonium, strontium, uranium, and iron nuclides and application to atmospheric deposition and aerosol samples

Summary

A procedure for the sequential radiochemical determination of plutonium, strontium, uranium and iron nuclides is described. The separation is carried out on a single anion exchange column. Pu(IV), U(VI) and Fe(III) are fixed on Bio Rad AG 1-X4 from 9 mol/l HCl, while the sample effluent is used for the determination of radio-strontium. Fe and U are eluted separately with 7 mol/l HNO₃, and Pu(III) is eluted with 1.2 mol/l HCl containing hydrogen peroxide. Subsequently, Pu and U are electrolysed and counted by alpha spectrometry. Radiostrontium is purified by the nitrate method and counted in a low level beta proportional counter. Fe is purified by extraction and cation exchange and ⁵⁵Fe is counted by X-ray spectrometry with a Si(Li) detector. The sample preparation and the application of the procedure to large samples, namely aerosols from 10⁵ m³ of air, and monthly deposition samples from 0.6 m² sampling area (10–100 l) are described. Chemical yields are for Pu 70±20, for Sr 80±15, for U 80–90, and for Fe 75±10%. As an example, the maximum airborne radionuclide concentrations determined with that procedure in fortnightly collected samples at Neuherberg after the Chernobyl accident were: ^239+240Pu, 2.58; ²³⁸Pu, 1.40; ²³⁸U, 0.65; ²³⁴U, 0.67; ⁹⁰Sr, 7600; and ⁵⁵Fe, 990 μBqm⁻³.

With appropriate changes in sample preparation, the procedure is applicable to other kinds of samples.