90Sr has a half life of 28.5y. It is chemically similar to Ca and enters the body through the food chain and collects in bones. It is a serious health hazard. How long in (years) will it take for 99.99% of Sr released in a nuclear reactor accident to disappear?
[Physics] Nuclear physics Radioactivity
homework-and-exercisesnuclear-physics
Best Answer
If initial mass is $M$. Amount remaining after $n$ half lives is $M/2^{n}$.
Ask yourself, How much remains after 99.99% is gone?
Equate.