90Sr determination in radioactive waste is currently supported by EichromTM Sr-spec concentration columns. This research was aimed at finding a faster and easier technique, leading to identical results. It was chosen to make use of the 3 M EmporeTM membranes.
It was deliberatly decided not to follow RP515 procedure (US Department of Energy). 90Y will be counted by liquid scintillation after EDTA elution. Official accreditation needs to verify every validation test.
Information concerning the specificity of the membranes has been reviewed. Uncertainty calculation of the activity, as well as the detection limit, are described. The enlarged uncertainty (k=2) reaches to about 10% for a 90Sr activity of 2 Bq/L. The detection limit obtained with this procedure reaches to about 50 mBq/L for a sample of 0.5 L and a 10 h counting time. A selectivity test detects the possibility of 89Sr presence which could disturb the 90Sr determination. Robustness of the method is mainly assured by the use of a tracer ( 85Sr as in RP515). The analysis of non aqueous biological samples has been carried out for accuracy. It required an adaptation of the preparation process. Linearity was tested on a range from 0 to 18.5 Bq/L 90Sr. The results of 38 routine samples obtained by the EmporeTM Sr Rad Disks were compared with those obtained by the Eichrom Sr-spec columns protocol. This comparison showed a good correlation between the two techniques.
Print ISSN: 0033-8230
Volume: 95, 09/2007
Pages: 529 - 534