After the sudden release of radioactivity from the Chernobylnuclear reactor acci
ID: 1758554 • Letter: A
Question
After the sudden release of radioactivity from the Chernobylnuclear reactor accident in 1986, the radioactivity of milk inPoland rose to 2 000 Bq/L due to iodine-131 present in the grasseaten by dairy cattle. Radioactive iodine, with half-life 8.04days, is particularly hazardous because the thyroid glandconcentrates iodine. The Chernobyl accident caused a measurableincrease in thyroid cancers among children in Belarus. (a) Forcomparison, find the activity of milk due to potassium. Assume thatone liter of milk contains 2.00 g of potassium, of which 0.011 7%is the isotope 40K with half-life 1.28 × 109 yr. (b) Afterwhat time interval would the activity due to iodine fall below thatdue to potassium?11. A small building has become accidentally contaminated
Explanation / Answer
Activity = Initial Activity*exp(-*t)_Iodine = ln(2)/8.04 days
=0.0862123359 per day
Activity of Iodine: 2000 Bq *exp(-6.4501196e-5*t)
_Potassium = ln(2)/1.28e9 yr *(1yr/365 day)
= 1.48361982e-12 per day
Activity of Potassium = 89.7125682*exp(-1.48361982e-12*t)
Activity Iodine = Activity of Potassium
2000 *exp(-6.4501196e-5*t) =89.7125682*exp(-1.48361982e-12*t)
Solve for t
exp(-6.4501196e-5*t + 1.48361982e-12*t) = 89.7125682/2000
exp(-6.45011945e-5*t) = 89.7125682/2000
t = ln(89.7125682/2000) / -6.45011945e-5
t = 48127.6604 days
t = 132 years