Activation analysis of zirconium, Zircaloy and nickel-base alloy for tantalum using extraction chromatography

Abstract

Extraction-chromatographic separation of ¹⁸²Ta from ⁹⁵Zr, ⁹⁵Nb, ⁵¹Cr, and ⁶⁰Co was performed using methyl isobutyl ketone (MIBK) sorbed on polytrifluoromonochloroethylene (Daiflon) particles as a stationary phase and 1N hydrofluoric and 2N hydrochloric acid as a mobile phase. The separation method was used for the determination of tantalum in zirconium, Zircaloy, and nickel-base alloy by neutron activation using ¹⁸²Ta ( T_1/2=115.1 days) produced by the reaction ¹⁸¹Ta(n, γ) ¹⁸²Ta.
The procedure is as follows : Samples (550 mg) together with standard solutions (Ta0.55μg, 0.0050.1 μg) were irradiated in JRR-2 at a thermal neutron flux of about 7×10¹³ n/cm²· sec for 20 min or at a flux of 2×10¹³ for 290 hr. The samples irradiated were cooled for about 30 days. Zirconium and Zircaloy were dissolved in 1N hydrofluoric acid- 2N hydrochloric acid. The nickel-base alloy was dissolved in a mixture of nitric and hydrochloric acids containing a few drops of hydrofluoric acid. The solution of zirconium, Zircaloy, or nickel-base alloy was adjusted to 1 N hydrofluoric acid- 2 N hydrochloric acid solution saturated with MIBK. Daiflon which sorbed MIBK was packed in a polyethylene column (Fig. 1), and the column was conditioned. The sample solution was poured into the column. The column was washed with 1 N hydrofluoric acid-2 N hydrochloric acid saturated with MIBK. Tantalum was retained on the column, but zirconium, niobium, chromium, and cobalt were not. Tantalum was eluted with 30 ml of hydrogen peroxide solution (30% H₂O₂ 1+20). The effluent was evaporated to about 3 ml and transferred to a polyethylene vial, and its volume was adjusted to 5 ml with 1 N hydrofluoric acid-2N hydrochloric acid. Counting was made with a 3×3 inch NaI (Tl) detector and a 400-channel pulse-height analyzer. The 1.05 to 1.55 MeV gamma rays of ¹⁸²Ta were used for the determination. The standard solutions were treated in the same way as the samples.
The recoveries of ¹⁸²Ta were more than 97%, and no correction for chemical yield was necessary. Retention of other nuclides on the column is shown in Table II. Only cerium was appreciably retained. Nuclides produced from zirconium, Zircaloy, and nickel-base alloy did not interfere with the determination of tantalum. In the presence of 0.4 m mole of oxalic acid, 1 m mole of sulfate, or nitrate, ¹⁸²Ta was quantitatively recovered. Tantalum in standard zirconium, Zircaloy, and nickel-base alloys was determined by using the above-mentioned procedure, and satisfactory results were obtained.