Nuclear energy produces about 10% of the world’s electricity and remains the largest single source of low-carbon power in many countries, yet its share has been slowly shrinking since the 1990s. The reasons aren’t primarily technical. Nuclear reactors work reliably and produce enormous amounts of energy from small amounts of fuel. The barriers are economic, political, and logistical, and they reinforce each other in ways that make new nuclear plants extraordinarily difficult to build.
The Cost Gap With Renewables
The simplest answer to why we don’t build more nuclear plants is money. The U.S. Energy Information Administration’s 2025 projections put the levelized cost of electricity from an advanced nuclear plant entering service in 2030 at $133.88 per megawatt-hour. For comparison, onshore wind comes in at $31.86 and solar at $37.82. That means nuclear electricity costs roughly three and a half to four times as much as its main low-carbon competitors.
These figures capture the full lifecycle cost of generating power: construction, fuel, operations, maintenance, and financing. Nuclear’s problem isn’t fuel (uranium is cheap) or operations (existing plants run economically for decades). The problem is construction. A nuclear plant requires an enormous upfront investment, often tens of billions of dollars, and that money is tied up for years before the plant generates a single watt. Solar and wind farms, by contrast, can be built in months to a couple of years, start earning revenue quickly, and scale in small increments rather than requiring one massive financial commitment.
This cost gap wasn’t always so wide. In the 1970s, nuclear was competitive with coal and gas. But renewable costs have plummeted over the past two decades while nuclear construction costs have risen in most Western countries. Investors and utilities now face a straightforward calculation, and nuclear rarely wins on price alone.
Construction Takes Too Long
Building a nuclear power plant is one of the most complex construction projects humans undertake. Modern large reactors in Western countries routinely take 10 to 15 years from initial planning to grid connection, and many projects blow past their original timelines by years. The two new reactors at Plant Vogtle in Georgia, the first new U.S. nuclear units in a generation, came online roughly seven years behind schedule and billions of dollars over budget.
Long construction timelines create a vicious cycle. Delays increase financing costs, since billions of dollars in loans accumulate interest for years before the plant earns revenue. Higher costs discourage the next project, which means fewer plants get built, which means the construction workforce and supply chain atrophy, which makes the next project even harder and more expensive. Countries that have maintained a steady pipeline of nuclear construction, notably South Korea, have kept costs and timelines far lower than countries that build reactors only sporadically.
Licensing Is Expensive and Slow
Before a single shovel of dirt is moved, a new reactor design must be certified by a national nuclear regulator. In the United States, the Nuclear Regulatory Commission charges applicants between $45 million and $70 million just for the design certification process, covering pre-application meetings, the formal review, and revisions. That’s before site-specific permits, environmental reviews, and construction licenses, each of which adds years and tens of millions more.
The regulatory process exists for good reason. Nuclear plants handle radioactive materials, operate under extreme temperatures and pressures, and must be designed to withstand earthquakes, floods, and aircraft impacts. But the cumulative effect is that only large, well-capitalized utilities or state-backed enterprises can absorb the regulatory costs and timeline risk. Startups developing small modular reactors face the same certification gauntlet, which is one reason those designs have been slow to reach the market despite decades of development.
The Unresolved Waste Problem
Every nuclear reactor produces radioactive waste, and the world still hasn’t figured out what to do with most of it. Since commercial nuclear power began in 1954 through the end of 2016, roughly 390,000 tonnes of spent fuel were generated globally. About two-thirds of that remains in storage, mostly sitting in pools or dry casks at the reactor sites where it was produced. The remaining third was reprocessed, primarily in France and Russia, to extract reusable material.
In terms of sheer danger, high-level waste (the spent fuel itself and byproducts of reprocessing) accounts for less than 1% of all radioactive waste by volume. But it remains intensely radioactive for thousands of years and requires deep geological isolation. Around 95% of radioactive waste is very low-level or low-level material that can be handled with relatively simple disposal methods. The challenge is that sliver of high-level waste.
Finland is the only country on track to permanently dispose of spent fuel underground. Its Onkalo repository, built 400 to 430 meters deep in ancient bedrock, can accommodate 6,500 tonnes of uranium in about 3,250 sealed canisters. Disposal is expected to begin in 2026. Every other nuclear-powered country is still searching for a site, fighting political opposition, or storing waste “temporarily” in arrangements that have lasted decades. The United States spent billions on Yucca Mountain in Nevada before the project was politically killed, and spent fuel remains scattered across more than 70 reactor sites nationwide. This unresolved question fuels public opposition and gives critics a powerful argument: why produce more waste when we can’t handle what we’ve already made?
Weapons Proliferation Concerns
Nuclear power and nuclear weapons share a common ingredient: fissile material. The civilian fuel cycle involves materials that either are, or could potentially be processed into, weapons-usable material. This connection has shaped international politics around nuclear energy for decades.
In practice, turning civilian reactor fuel into a weapon is not straightforward. Spent fuel from a standard reactor contains plutonium, but extracting it requires complex chemical separation (reprocessing), and the isotopic mix is far from ideal for weapons. The physical design of reactors also creates barriers. Accessing fuel inside an operating reactor means physically opening a massive, heavily shielded pressure vessel, a process that’s difficult to conceal. These technical hurdles don’t make proliferation impossible, but they add layers of difficulty that international inspectors can monitor.
Still, the concern is real enough to constrain nuclear expansion. When a country announces plans to enrich uranium or build reprocessing facilities, the international community pays close attention, because the same technologies that make reactor fuel can, with modifications, produce weapons-grade material. This is why Iran’s enrichment program and North Korea’s reactors have been geopolitical flashpoints. Countries that want to sell nuclear technology must navigate export controls, and buyer nations must accept intrusive inspections. These diplomatic complications don’t apply to solar panels or wind turbines, giving renewables a geopolitical simplicity that nuclear lacks.
Public Fear and Political Risk
Three major accidents define public perception of nuclear power: Three Mile Island in 1979, Chernobyl in 1986, and Fukushima in 2011. Each triggered waves of policy change. After Fukushima, Germany accelerated its phase-out of all nuclear plants. Italy voted against restarting its nuclear program. Japan shut down its entire fleet for years.
The statistical safety record of nuclear power is strong. Per unit of energy produced, nuclear causes fewer deaths than coal, oil, natural gas, and even some renewables when full lifecycle risks are counted. But nuclear accidents, though rare, are dramatic and long-lasting. Evacuation zones, uninhabitable land, and elevated cancer risk carry a psychological weight that annual air pollution deaths from fossil fuels do not. Politicians know that approving a nuclear plant means accepting the (very small) risk of a career-ending disaster. Approving a wind farm carries no such political downside.
This asymmetry between statistical risk and perceived risk makes nuclear uniquely vulnerable to political shifts. A single accident anywhere in the world can derail nuclear programs in countries thousands of miles away. No other energy source faces this dynamic.
Why Nuclear Still Has Advocates
Despite all these obstacles, nuclear energy has characteristics that no other clean energy source fully replicates. It generates power around the clock regardless of weather, occupies a tiny land footprint compared to wind and solar farms, and produces zero carbon emissions during operation. A single reactor can power hundreds of thousands of homes for 40 to 60 years.
These qualities make nuclear particularly valuable for grid stability. Solar and wind are intermittent, meaning they need backup from batteries, gas plants, or other dispatchable sources. As grids push toward 100% clean electricity, the cost of managing that intermittency rises. Some energy analysts argue that including nuclear in the mix could lower the total system cost of decarbonization, even if nuclear’s per-kilowatt cost is higher than renewables alone.
Several countries are betting on this logic. France generates about 70% of its electricity from nuclear and has some of the lowest carbon emissions per kilowatt-hour in Europe. China and India are building dozens of new reactors. The U.S., U.K., and Canada are investing in small modular reactor designs that aim to cut costs by standardizing components and building them in factories rather than on-site. Whether these newer designs can actually deliver cheaper, faster nuclear power remains an open question, but the interest reflects a growing recognition that hitting climate targets without any nuclear energy will be harder and possibly more expensive than hitting them with it.