[newer]

question: Some soil contains 3ppb(parts per billion by weight) U-238. Calculate the specific activity of the soil??


t(1/2)=half life = 4.468*10^9(y)
mass M=238

the activity of 1g U-238:

A= (6.02*10^23)*ln(2)/[t(1/2)]*M
= (6.02*10^23)*0.693/(4.468*10^9)*238
= 12445Bq/g

3ppb=3/10^9(g)

Finally, A = [3/10^9(g)]* (12445Bq/g)=3.6735/10^5Bq/g=9.93/10^13Ci/g

Is it right? Thanks!!