Chernobyl will be radioactive for many centuries , and the hottest parts may remain dangerous for thousands of years. Shorter-lived isotopes like cesium-137 and strontium-90 fade over decades, but longer-lived contamination near the reactor and in hotspots such as the Red Forest lasts much longer.
Practical timeline
- Some outer areas: already low enough for limited visits or controlled work.
- Much of the exclusion zone: may keep becoming safer over the next 50 to 100 years as the main shorter-lived isotopes decay.
- Inner hotspots and reactor-adjacent areas: can stay unsafe for centuries to millennia.
Simple answer
If you mean “when will it be completely gone,” the honest answer is not anytime soon —radioactivity will still be present far beyond any human lifetime, though the danger keeps dropping over time. If you mean “when can parts of it be used safely again,” some areas already can be, and more may become usable gradually over the coming decades.
Why it lasts so long
Different radioactive materials decay at different rates. The fast-changing ones are mostly gone after decades, but long-lived isotopes and contaminated fuel debris make the most damaged zones a very long-term hazard.
TL;DR
- Still radioactive now: yes.
- Safer in parts: yes, already.
- Fully safe everywhere: likely thousands of years for the worst areas.