how long is nuclear waste dangerous

Nuclear waste remains dangerous for a very long time, with the most hazardous high-level waste remaining significantly radioactive for hundreds of thousands to up to a million years. The radioactivity of nuclear waste gradually decreases over time, but some isotopes, especially those in high-level waste, have long half-lives ranging from thousands to hundreds of thousands of years. For example, plutonium-239 has a half-life of about 24,000 years, and waste can remain hazardous and require safe storage for up to a million years according to some estimates. However, after about 300 to 500 years, the strongest gamma radiation decreases substantially, making it safer to be near, though still harmful if ingested. Nuclear waste management involves storing and shielding this material safely to prevent exposure for these extended periods.