Slash Gear reported that nuclear reactors are not limited to 40 years of operation, as initial limits reflected construction payback math rather than technical limits. Initial operating licenses in the United States were granted for 40 years, but modern research indicates facilities can safely run longer with proper maintenance.
The US Nuclear Regulatory Commission has granted 20-year license extensions for years after operators proved equipment safety. Most American reactors have received these approvals, and several units secured second extensions allowing operation up to 80 years.
The US Department of Energy noted no technical barrier automatically stops operation at 80 years, with scientists researching safe use for up to a century. As of March 2026, the average age of a US nuclear reactor is about 44 years.
Decommissioning and oldest units
When reactors shut down, decommissioning takes decades. Nuclear fuel is removed before equipment and site areas are cleaned of radioactive contamination and checked by regulators. Experts use three main decommissioning methods: immediate dismantling, entombment in concrete, or safe storage (SAFSTOR), where facilities are mothballed for 40 to 60 years until radiation decreases naturally.
The safe storage method is being used at the Chernobyl Nuclear Power Plant, where full dismantling will finish in the 2060s. Meanwhile, the world's oldest operating reactors are the first and second units at India's Tarapur Nuclear Power Plant, launched in 1969 and recommissioned in 2026 after major reconstruction and equipment replacement. Other 1969 reactors include Switzerland's Beznau-1 and the Nine Mile Point-1 unit in the US.
