Is this Y-90 accumulation where you get one Y-90 decay per Sr-90 decay similar to saturation in pharmacokinetics where at 5 half-lives the levels are 'stable'?

Assuming Sr-90 and Y-90 are pure beta emitters, does this mean that if I start with pure Sr-90 at x Bqs, given some time I'll actually end up with more radioactivity in the system, as in the combined Bqs of Sr-90 and Y-90 will be greater than the initial radioactivity of pure Sr-90?

not_nattyOP t1_jbxy8gs wroteReply to comment by

mfb-inIs Radioactivity Inversely Proportional to Half Life?bynot_nattyIs this Y-90 accumulation where you get one Y-90 decay per Sr-90 decay similar to saturation in pharmacokinetics where at 5 half-lives the levels are 'stable'?

Assuming Sr-90 and Y-90 are pure beta emitters, does this mean that if I start with pure Sr-90 at x Bqs, given some time I'll actually end up with more radioactivity in the system, as in the combined Bqs of Sr-90 and Y-90 will be greater than the initial radioactivity of pure Sr-90?