The material used in nuclear bombs is ²³⁹Pu,with a half-life of about 20,000 years.How long must we wait for a buried stockpile of this substance to decay to 4% of its original ²³⁹Pu mass?

Question

Quizplus · Accepted Answer

To decay to 4% of its original mass, the substance must go through enough half-lives such that only 4% remains. This is equivalent to 4% = (1/2)^n, where n is the number of half-lives. Solving for n gives approximately 4.64 half-lives. Multiplying 4.64 by the half-life of 20,000 years gives approximately 93,000 years.

The Material Used in Nuclear Bombs Is 239Pu,with a Half-Life

The Material Used in Nuclear Bombs Is ²³⁹Pu,with a Half-Life