ABSTRACT
This study describes a new determination of the decay scheme and half-life of (93)Zr. A pure (93)Zr solution was obtained after chemical separation from the dissolution of an irradiated zircaloy sample. The concentration of (93)Zr in the solution was measured by mass spectrometry, with an isotopic dilution technique. The activity of the solution was measured by liquid scintillation counting, using an efficiency tracing method. The measurement of the activity concentration of (93)Nb(m) by X-ray spectrometry, allowed the determination of the (93)Zr decay scheme and the calculation of the (93)Zr detection efficiency. This leads to the calculation of the decay probability of (93)Zr toward (93)Nb(m) of (0.73+/-0.06) and to a half-life of (93)Zr of (1.64+/-0.06)x10(6) years. These values are discussed in comparison with the evaluated values available in the literature.
ABSTRACT
A chemical separation method has been developed for the determination of (99)Tc in various types of radioactive wastes. Such a method includes (i) fusion with NaOH, (ii) extraction in a column containing methyltrioctylammonium chloride, (iii) extraction by solvent with N-benzoyl-N-phenylhydroxylamine and, (iv) measurement by inductively-coupled plasma mass spectrometry (ICP-MS). From the performance standpoint, the recovery of (99)Tc, using (99m)Tc as a yield tracer, is higher than 70%. This analytical method, as developed, ensures effective decontamination with respect to the radionuclides, insofar the decontamination factors are greater than 10(+5), whenever the residual activity may be measured. Taking into account a 3sigma counting error, the detection limit obtained with the ICP-MS technique is 1.9 mBq/ml; the method enabling hence to detect activities as low as 0.3 Bq/g, with analysed samples of 0.2 g and a radiochemical yield of 70%. Studies have been dedicated to the (99)Tc measurement, using the electrothermal vaporization ICP-MS technique, which lowers the detection limit by a factor 10, with the standard solution (0.3 pg/ml), compared with the previous ICP-MS technique.
