Small Modular Reactors (SMR) promise to reshape nuclear power by making reactors factory built, cheaper to construct, safer, and more flexibly sited. This guide covers the technology, leading designs, and where SMR deployment actually stands.
What makes SMRs different
| Attribute | Conventional nuclear | SMR |
|---|---|---|
| Size | 800 to 1,600 MW | 10 to 300 MW |
| Construction | Site built over decade | Factory built, transported to site |
| Cost per unit | USD 5 to 15 billion | USD 500 million to 3 billion targeted |
| Safety systems | Active | Increasingly passive |
| Deployment timeline | 10 to 15 years | 4 to 7 years targeted |
| Siting | Large sites near water | Compact, more flexible siting |
Why now
- Rapidly growing electricity demand from AI data centres.
- Interest in firm low carbon generation.
- Falling clean energy investment costs generally.
- Federal support through IRA and DOE programmes.
- Corporate net zero commitments requiring firm clean power.
- Aging existing nuclear fleet.
Leading SMR designs
| Design | Developer | Status |
|---|---|---|
| NuScale VOYGR | NuScale Power (US) | NRC design certification complete; Utah project cancelled 2023 |
| BWRX 300 | GE Hitachi | Ontario Darlington first commercial project |
| Natrium | TerraPower (Bill Gates) | Wyoming project under construction |
| Xe-100 | X-energy | Dow Chemical Texas partnership |
| Rolls-Royce SMR | Rolls-Royce SMR (UK) | UK design assessment |
| eVinci | Westinghouse | Microreactor programme |
| ACP100 (Linglong One) | CNNC (China) | China Hainan first grid connected SMR |
| Kairos KP-FHR | Kairos Power | Molten salt cooled, TVA partnership |
China leadership
China ACP100 in Hainan Province became the world first grid connected SMR in 2024. Chinese SMR programme is well ahead of US and Western competitors in actual deployment.
Darlington BWRX 300
Ontario Power Generation Darlington project is the leading Western SMR construction, targeting first grid connection around 2029. Uses GE Hitachi BWRX 300 design. Second reactor site being pursued.
Natrium
TerraPower Natrium in Wyoming uses sodium fast reactor design with molten salt thermal storage. Enables load following capability. First construction started 2024, commercial operations targeted late 2020s.
Industrial applications
Data centre partnerships
Amazon (Talen Energy), Google, Microsoft (Constellation), and Meta all announced nuclear power partnerships. Growing AI electricity demand is driving nuclear deals. Some specifically involve SMRs.
Policy support
| Support | Value |
|---|---|
| DOE Advanced Reactor Demonstration Program | Multi billion dollar deployment support |
| IRA Advanced Nuclear PTC | New plants receive PTC |
| DOE loan programme (Section 1706) | Loan guarantees |
| Streamlined NRC licensing | ADVANCE Act reforms |
| UK Great British Nuclear | SMR selection process |
| Canada Innovation Program | SMR deployment support |
Contemporary challenges
- Construction cost inflation eroded early designs (NuScale cost overruns).
- NRC licensing timeline still lengthy.
- Public acceptance variable.
- Fuel supply for advanced designs (HALEU).
- Workforce constraints in nuclear industry.
- Waste management remains unresolved.
- Financing at scale untested.
HALEU fuel supply
Many advanced SMRs need High Assay Low Enriched Uranium (HALEU) fuel. US supply chain limited. DOE programme scaling HALEU production. Russia was historically major HALEU source but now sanctioned.
Waste
Cost trajectory
NuScale Utah project cancelled 2023 with cost estimates rising to USD 20,000+ per kW. Actual first of a kind SMR costs likely USD 8,000 to 15,000 per kW. Nth of a kind targeted USD 3,000 to 5,000 per kW. Whether scale up delivers cost reductions remains uncertain.
Microreactors
Sub 10 MW microreactors for remote sites, military bases, mining operations. Radiant Nuclear, Oklo, Westinghouse eVinci, and others developing. Different market than utility scale SMR.
SMR vs fusion
SMR is fission technology, mature and commercial. Fusion is different technology, still research despite recent progress. Do not confuse. See our companion article on hydropower turbines for another distinct technology category.
Realistic deployment timeline
Where SMRs are going
- Chinese and Russian deployment continuing.
- US and UK first commercial units late 2020s.
- Data centre partnerships growing.
- Industrial heat applications emerging.
- Cost trajectory uncertain but potentially competitive.
- Consolidation of designs likely as market matures.
Frequently asked questions
What is an SMR?
Small Modular Reactor, typically 10 to 300 MW factory built nuclear reactor.
Are SMRs safer?
Designs feature passive safety systems, generally safer than conventional.
Are they cheaper?
Per unit yes; per kW uncertain. Awaiting real world data.
Are they operating anywhere?
Yes in China (ACP100). Western commercial units late 2020s.
What is a microreactor?
Sub 10 MW reactor for very small applications.
Do they still produce waste?
Yes. Waste challenge unchanged.
How long to build?
4 to 7 years targeted; may take longer in reality.
Who funds SMRs?
DOE, IRA credits, private equity, utility investment.
Are data centres buying?
Yes. Big Tech has major nuclear deals.
Where can I read more?
DOE, World Nuclear Association, developer sites.
Summary
Small Modular Reactors could reshape nuclear power through factory construction, passive safety, and flexible siting. China leads with the first grid connected SMR. Western designs targeting late 2020s commercial operation. Growing data centre partnerships and industrial heat applications create demand. Cost trajectory remains uncertain. Waste and public acceptance challenges persist. If cost targets are met, SMRs become a meaningful low carbon option through the 2030s and beyond.
Next reading
- Global electricity mix
- Renewable vs non renewable
- How the electric grid works
- Browse the UtilityRadar directory
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