Question

8. You have been tasked with disposing of some radioactive waste from the manufacture of medical imaging agents. The main radioactive isotope in this waste is 131 I (which has a half-life of ~8.0 days and decays primarily via a β- mechanism). There are companies that specialize in the disposal of

radioisotopes, but they are very expensive. The local landfill has agreed to allow you to dispose of the waste as long as the radioactivity is below 2 x 10-4 mCi.

a.) If the waste origi

nally has an activity of 10 Ci, how long would you have to store the waste to be able to dispose of it in the landfill? (Remember to show your work for full credit)

b.) What kind of container should you store the waste in while it’s decaying?

Answer 1

Ao = 10 Ci

A = 2 x 10^-4 mCi = 2 x 10^-7 Ci

t_1/2 = 8 days

λ = 0.693/t_1/2 = 0.693/8 = 8.66x 10^-2 day^-1

A = Aoe^(-λt)

ln A = lnAo -λt

ln 2x10^-7 = ln 10 - 8.66x10^-2 xt

-15.42= 2.30 - 8.66x10^-2 xt

t = 2.30 + 15.42/8.66x10^-2

t = 204.6 days

It will take 204.6 days long to store the waste to be able to dispose of it in the landfill.

b, What kind of container should you store the waste in while it’s decaying?

The ideal container to store beta emitting radionuclide is aluminium metal which will stop the radiation and contain it.

answered by: anonymous