How do you find radioactive decay-that is over 50% ?

A nuclear reactor that generates heat for a nuclear power plant is located in San Luis Obispo, California. The nuclear waste generated by PG&E at the facility stays on-site in storage containers. ume that we have one ton of waste product Plutonium-239 on site today. How much time must p before about 99.6% of it has decayed to other products. Pu-239 has a half life of 2.4 X 104 years.