Question

Suppose you are a health physicist and you are being consulted about a spill occurred in a radio chemistry lab. The isotope spilled out in the lab was 500 micro cure of ¹³¹Ba which has half-life of 12 – days.

1. What is the decay constant of ¹³¹Ba

2. Your recommendation is to clear the lab until the radiation level is down to 1 micro curie. How length will the lab have to be closed.

Answer 1

1.  λ = \(\frac{0.693}{T_{1/2}} =\frac{0.693}{12\times24\times60\times60}\) = 6.6 x 10^-7

2.  9 × 12 = 108 days.