Nuclear energy costs between roughly $80 and $100 per megawatt-hour to produce, making it one of the more expensive sources of new electricity in the U.S. today. But that number hides enormous variation depending on where a plant is built, how it’s financed, and whether you’re talking about a brand-new reactor or one that’s already been running for decades. The upfront construction cost is by far the biggest factor, and it’s where nuclear projects most often go off the rails.
Why Construction Costs Dominate
Nuclear power is unusual among energy sources because the vast majority of its lifetime cost is locked in before the plant generates a single watt. The U.S. Energy Information Administration puts the overnight capital cost of a new large light-water reactor at about $7,800 per kilowatt, or closer to $8,100 per kilowatt when regional cost differences are factored in (in 2024 dollars). “Overnight cost” is the price tag if you could build the plant instantly, with no interest payments piling up during construction. In reality, nuclear projects take years to complete, and financing costs can add billions more.
For comparison, a utility-scale solar farm costs roughly $1,100 to $1,400 per kilowatt to build, and a natural gas combined-cycle plant comes in around $1,200 per kilowatt. Nuclear’s construction price tag is five to seven times higher. The tradeoff is that once built, a nuclear plant runs for 60 to 80 years with relatively low fuel and operating expenses. But those upfront costs have to be paid off through electricity sales over decades, and the interest rate on borrowed money matters enormously. Even a one-percentage-point increase in borrowing costs can raise the final price of nuclear electricity by 10% or more.
The Vogtle Reality Check
The most recent nuclear construction project in the United States offers a sobering case study. Vogtle Units 3 and 4 in Georgia, the first new reactors built in the country in a generation, came online in 2023 and 2024 at a total cost exceeding $30 billion. The original budget was roughly $14 billion. Construction took about twice as long as planned, with delays driven by design changes, supply chain problems, workforce shortages, and the challenge of building something no American construction crew had done in decades.
Vogtle’s two new reactors produce about 2,200 megawatts combined. At $30 billion, that works out to roughly $13,600 per kilowatt, far above the EIA’s reference estimate. This kind of cost escalation has been the norm for nuclear projects in Western countries. Large, complex, one-of-a-kind construction projects are inherently vulnerable to delays, and every month of delay adds financing costs on top of direct construction expenses.
How China Builds for Less
Not every country faces the same cost problem. A 2025 Johns Hopkins University analysis found that new nuclear plants in the U.S. cost as much as $15 per watt (equivalent to $15,000 per kilowatt), while France’s latest reactors come in above $4 per watt. China, however, is building highly standardized plants for about $2 per watt, roughly one-seventh of the American price.
The difference comes down to repetition and workforce experience. China has built dozens of reactors using the same design, so construction crews know exactly what they’re doing, supply chains are established, and regulatory processes are streamlined for a familiar product. In the U.S. and Europe, each new project feels like reinventing the wheel. Workers and contractors lack recent experience, designs get modified mid-construction, and regulatory reviews stretch out timelines. The physics of nuclear energy isn’t inherently expensive. The construction management is.
What You Pay for Fuel and Operations
Once a nuclear plant is running, fuel costs are remarkably low. Uranium fuel accounts for only about 10% to 15% of the total cost of nuclear electricity. A single uranium fuel pellet the size of a pencil eraser contains as much energy as a ton of coal, so very small quantities of fuel power the plant for 18 to 24 months between refueling outages. This makes nuclear electricity prices stable and largely immune to the fuel price swings that affect natural gas plants.
Operating and maintenance costs add another layer. A typical plant employs 500 to 700 people, runs continuous safety monitoring, and requires periodic equipment upgrades. These costs are meaningful but predictable, generally ranging from $25 to $35 per megawatt-hour. For plants that have already paid off their construction debt, the combination of low fuel and moderate operating costs makes nuclear one of the cheapest sources of electricity on the grid, often competitive with natural gas at $25 to $30 per megawatt-hour.
Small Modular Reactors and Future Costs
Small modular reactors, or SMRs, are designed to sidestep the construction cost problem by building smaller units (typically 50 to 300 megawatts instead of 1,000+) in factories and shipping them to sites for assembly. The theory is that factory production brings costs down through standardization, the same advantage China has demonstrated at larger scale.
Current projections are mixed. The EIA estimates overnight capital costs for SMRs at about $9,500 per kilowatt, actually higher than large reactors on a per-kilowatt basis. Academic modeling from Applied Energy found more optimistic numbers in the range of $4,000 to $5,000 per kilowatt, with electricity costs of $80 to $90 per megawatt-hour. A Monte Carlo simulation in that same analysis suggested the most common SMR design would likely cost between $4,250 and $6,400 per kilowatt, with construction taking 3.4 to 6 years. No commercial SMR is operating in the U.S. yet, so these remain projections rather than proven costs.
The Cost of Shutting Down
Nuclear plants don’t just stop costing money when they stop generating power. Decommissioning, the process of safely dismantling a reactor and cleaning up the site, is a significant expense that plant owners are required to plan for throughout the reactor’s operating life. The NRC’s minimum formula-based estimate for decommissioning a single reactor unit is about $559 million. But site-specific analyses, which account for the full scope of work, typically come in much higher. One recent filing for a single-unit plant estimated decommissioning at roughly $1.1 billion in 2023 dollars.
Spent fuel management adds to the bill. In that same filing, storing used fuel on-site until the federal government eventually takes possession accounted for about 7.2% of the total decommissioning cost, or around $79 million. Because the U.S. still has no permanent repository for spent nuclear fuel, plant owners must maintain on-site storage facilities indefinitely, an open-ended cost that’s difficult to estimate precisely. Plant operators set aside money throughout the reactor’s lifetime into dedicated trust funds to cover these eventual expenses, so the cost is built into the electricity price customers pay during the plant’s operating years.
How Nuclear Compares Overall
The full cost picture depends heavily on what you’re comparing. For new construction in the U.S. and Europe, nuclear is significantly more expensive than wind, solar, or natural gas on a per-megawatt-hour basis. The high upfront cost and long construction timelines create financial risk that pushes investors toward cheaper, faster-to-build alternatives.
For existing plants that are already built and paid off, the equation flips. Operating nuclear plants produce electricity for $25 to $35 per megawatt-hour, making them among the cheapest generators on the grid. This is why there’s strong economic logic behind extending the licenses of existing reactors to 60 or 80 years rather than building new ones. The capital investment has already been made, and the incremental cost of continued operation is far below the cost of replacing that capacity with anything else.
Nuclear also provides something that’s hard to put a dollar figure on: 24/7 carbon-free electricity regardless of weather. Wind and solar are cheaper to build but require backup generation or battery storage for cloudy, calm days. When those system-level costs are included, the gap between nuclear and renewables narrows, though by how much remains actively debated among energy economists.