The Real Cost of Building an SMR: 5 Numbers That Matter

The industry pitch is cheap, fast, and factory-built, but five specific dollar figures tell a much messier story.

Every SMR pitch deck opens the same way: smaller reactors, built in factories, stamped out like Toyotas instead of hand-carved like cathedrals. 💰 Cheaper by design, faster to build, easier to finance. It’s a great story, and parts of it are even true. But the nuclear industry has a long, expensive habit of promising one number and delivering a very different one, and the SMR wave so far hasn’t broken that habit. 📉 Here are five real dollar figures, not projections, not vendor slide-deck math, that show what building one of these things actually costs right now.

The number that punctured the hype

$9.3 billion. That’s what NuScale’s flagship US project, the Carbon Free Power Project in Idaho, was projected to cost by the time it collapsed in November 2023, up from an original $5.3 billion estimate just two years earlier. A 75 percent jump in construction cost pushed the target power price from $58 to $89 per megawatt-hour, and that’s before accounting for inflation between now and whenever the plant would have actually opened. 📊 The Utah utilities that had signed up for the power backed out, subscriber by subscriber, until there weren’t enough left to justify finishing it.

Here’s the number that really stings: once you divide that final $9.3 billion by the plant’s planned 462 megawatts, NuScale’s project worked out to roughly $20,139 per kilowatt, according to IEEFA’s analysis of the cost estimate. That’s essentially the same price per kilowatt as the infamously over-budget Vogtle expansion in Georgia, the very poster child for large nuclear’s cost problems that SMRs were supposed to fix. If the factory-built promise can’t beat the thing it’s replacing on a dollar-per-kilowatt basis, what exactly is the pitch? 🤔

A few reasons that estimate ballooned so fast:

• Commodity and steel prices climbed sharply between 2021 and 2023

• Interest rates used in the project’s financing model rose roughly 200 basis points

• The project shrank from twelve modules to six, losing economies of scale it was counting on

• Licensing, safety review, and quality assurance costs kept adding years and dollars

The baseline these projects are trying to beat

To be fair to SMR developers, large nuclear’s own track record isn’t exactly a high bar to clear. 📉 Vogtle Units 3 and 4 in Georgia, the only new nuclear reactors completed in the US in the past three decades, were originally priced at $14 billion. By the time Unit 4 finally came online in 2024, seven years late, the total had climbed past $34 billion, according to Wikipedia’s detailed construction history. That’s more than double the original number, on a project built by an experienced utility with federal loan guarantees behind it. 🏗️

The Vogtle math, in the numbers that actually moved:

• $14 billion: the original 2008 estimate for both new reactors

• $25 billion: the revised total by 2018, after Westinghouse’s bankruptcy

• $34 billion: the final tally once Unit 4 entered service in 2024

• 7 years: how far behind schedule the project ultimately ran

This is the real comparison SMRs need to win, not against solar or wind, but against the nuclear industry’s own history of blown budgets. And so far the early data suggests SMRs are inheriting the same disease rather than curing it. 💸 Have you noticed how every big infrastructure story eventually turns into a story about who pays for the overrun?

The one real number instead of a promise

Not every SMR cost figure is a cautionary tale. 🏗️ GE Hitachi’s BWRX-300 is actually under construction right now at Ontario’s Darlington site, and its current price tag is a real, audited estimate rather than a vendor projection. As of May 2025, the project was estimated to cost at least CAD $7.7 billion, working out to roughly €15,870 per kilowatt, per analysis from the Heinrich Böll Foundation’s Brussels office. That’s still expensive by any normal standard, but it’s a number attached to concrete actually being poured, not a slide in an investor deck. 💵

That distinction matters more than it sounds. A project with:

• A signed construction contract and a utility actually pouring foundations

• Regulatory approval already secured rather than pending

• A single owner (Ontario Power Generation) absorbing the financial risk

• A real, if painful, price tag instead of an aspirational one

is simply a different category of investment than one still selling subscriptions to future power. 📋 If you want the underlying financials tracked deal by deal instead of piecing them together from press releases, SMRbrief Pro keeps a running ledger of what every active project actually costs versus what it originally promised.

The gap that supposedly closes with scale

Here’s the number every vendor is betting the whole business model on: today’s first-of-a-kind (FOAK) SMRs run somewhere between $80 and $150 per megawatt-hour, while vendors promise that Nth-of-a-kind (NOAK) production, once a design has been built dozens of times, drops that to $50 to $80 per megawatt-hour. ⚡ The Department of Energy has floated an even more optimistic long-run figure of around $60/MWh if designs get standardized and mass-produced. 📉

The catch is how many units it actually takes to get there. Industry estimates suggest the cost curve doesn’t flatten out until somewhere between 5 and 7 identical units, or 10 to 20 gigawatts of installed capacity, based on techno-economic modeling published through the Department of Energy. South Korea needed to build 24 nearly identical reactors before it saw meaningful cost reductions on its fleet. 🔁

Right now, the field looks like this:

• NuScale: light-water design, one canceled US project, pursuing Romania and Poland instead

• TerraPower: sodium-cooled Natrium, one unit under construction in Wyoming

• X-energy: high-temperature gas design, backed by Amazon, still pre-construction

• GE Hitachi: BWRX-300, the only design actually pouring concrete, in Canada

Five different designs, five separate learning curves, and not one of them has built a second unit yet, let alone a fifth. 🔢

So the real number that matters isn’t $60 or $80 or $150 per megawatt-hour. It’s the number of identical reactors any single company needs to actually build before its own promised price shows up on a customer’s bill, and right now that number is closer to zero than anyone in the industry likes to admit. Which of these five numbers would you want written into a power contract before signing it?