Chemical separation of strontium from other fission and corrosion products involves precipitations of SrCO3 and Sr(NO3)2. The gross activities of purified Sr-89 and Sr-90 are first measured. Yttrium-90 is then allowed to grow into the strontium sample, and at a later time, the Y-90 activity is separated and measured. The Sr-90 activity is calculated from the Y-90 activity, and the Sr-89 activity is calculated from the difference between the total Sr-89 and Sr-90 activities measured and the calculated Sr-90 activity. A general scheme of analysis is shown below:
Chemical separation for Sr-89 and Sr-90. Record time of separation, t1.
Mount SrCO3 and count immediately.
Hold SrCO3 for at least 10 days for Y-90 growth.
Milk Y-90 from SrCO3 and record time of separation, t2.
Mount Y2O3 and count Y-90 activity at t3.
Recount Y2O3 for a 64.1 hr half-life decay to check purity of separation.
Calculate Sr-90 activity from Y-90 activity.
Calculate Sr-89 activity from total and Sr-90 activities.
The following three procedures are described:
Preparation of counting efficiency curves for Sr-89, Sr-90 and Y-90.