You are a radiation expert for the state of Colorado when you receive notification of an
overturned semi carrying radioactive waste. Out of the twenty containers the truck was carrying,
ten ruptured, exposing the local community of approximately 300,000 residents to potentially
lethal radiation. You quickly manage the situation with the local HAZMAT team evacuating the
residents and diverting all traffic around the spill and away from harm.
You find the manifest and notice the truck was carrying spent nuclear fuel consisting of depleted
uranuim and plutonium. You communicate this to the chief HAZMAT officer who asks the
following question:
If uranium-238 has a half-life of $4.39 \times 10^9$ years, how many millennium (1000 years) will it take
for 8 grams of depleted uranium to be depleted by 0.4 grams of its original mass?
(Round to the nearest whole number)
