Is nuclear energy renewable?

Renewable is not a physical property of an energy source. It is a category that energy-statistics agencies define using the same underlying test: whether the resource replenishes through a natural process on a timescale comparable to the rate at which it is consumed. Sunlight, wind, the water cycle and geothermal heat pass that test because they are continuous flows. Uranium does not: it is a mineral mined from the ground, like coal or natural gas, and an atom that fissions does not re-form. That is why the U.S. Energy Information Administration (EIA) defines renewable energy as coming from sources that are naturally replenishing but flow-limited, and classifies uranium explicitly as a nonrenewable energy source, in the same category as fossil fuels, reserving renewable for solar, wind, water, biomass and geothermal.

The IAEA and the OECD Nuclear Energy Agency (NEA) jointly publish the world's uranium inventory every two years, the Red Book. The Uranium 2024 edition put identified resources, reasonably assured plus inferred, at 7,934,500 tonnes of uranium recoverable below USD 260/kgU, as of 1 January 2023; at a lower extraction cost, below USD 130/kgU, the figure is 5,925,700 tonnes. The same report put reactor-related uranium requirements at 59,018 tonnes of uranium in 2022, the latest year with actual, not projected, data. Combining those two numbers, the cheaper identified resources cover about 100 years of supply at the 2022 consumption rate, before counting undiscovered uranium or further exploration.

That math changes with technology. Reprocessing spent fuel, separating the uranium and plutonium still usable from the fission products, cuts how much natural uranium is needed: France, which has recycled light-water-reactor fuel since the 1980s, has reduced its natural uranium consumption by up to 25% a year through this mono-recycling, per the IAEA. The larger gain sits with fast reactors, which also fission uranium-238, 99.3% of natural uranium that light-water reactors leave untouched, and which the IAEA says could extract 60 to 70 times more energy from the same kilogram of uranium in a closed fuel cycle. Today that technology runs commercially on only two Russian units, Beloyarsk 3 and 4, so the multiplier is a technical ceiling, not reserves already on the books.

Under that same definition, the one the EIA and most energy agencies use, nuclear power does not qualify as renewable. That is a separate question from low-carbon: the two categories overlap for some sources, hydropower is both, but not for all, and the life-cycle emissions figures for each technology are in the entry Is nuclear energy clean?