Learn About SMRs

An SMR is a nuclear reactor with an electrical output typically under 300 MWe — roughly one-third the size of a conventional nuclear plant. "Modular" means they can be factory-fabricated and transported to site, reducing construction complexity. Many SMR designs incorporate passive safety features that rely on natural physics rather than active systems.

Modern SMR designs are engineered with multiple layers of passive safety. Many designs physically cannot melt down — they use natural convection, gravity, and negative temperature coefficients to shut down automatically without human intervention or external power. The smaller core size also means a smaller source term in the event of any incident.

First-of-a-kind SMR costs are high — estimates range from $5,000 to $15,000 per kW for initial deployments. However, the modular factory-built approach is expected to drive costs down significantly with serial production. The target for nth-of-a-kind units is $3,000–$5,000/kW, which would make them competitive with other clean energy sources when accounting for capacity factor.

Most SMR designs use uranium fuel, but with varying enrichment levels. Many use Low-Enriched Uranium (LEU) under 5% — the same as conventional reactors. Some advanced designs require High-Assay Low-Enriched Uranium (HALEU) enriched to 5-20%. A few designs use thorium or even spent nuclear fuel. The enrichment level affects performance, refueling intervals, and proliferation considerations.

Once factory manufacturing is established, SMR proponents target 3-4 year construction timelines — significantly shorter than the 10-15 years common for large conventional reactors. The modular approach means major components arrive pre-fabricated and pre-tested, reducing on-site construction time and quality risks.

SMRs produce nuclear waste similar in nature to conventional reactors, but in smaller quantities due to their size. Some advanced designs — particularly fast-spectrum and molten salt reactors — can actually consume existing nuclear waste as fuel, potentially reducing the overall waste problem. All waste requires careful long-term management regardless of reactor type.

Yes — this is one of the most promising near-term applications. Hyperscale data centers need 100-500 MW of reliable, 24/7 baseload power. SMRs are ideally sized for co-location, providing carbon-free electricity directly to the facility. Several major tech companies have announced partnerships with SMR developers specifically for data center power.

Thermal reactors use a moderator (usually water or graphite) to slow neutrons down, making fission more likely with lower-enriched fuel. Fast reactors operate without a moderator, using high-energy neutrons. Fast reactors can breed new fuel, burn waste, and operate on a wider range of fuels, but are more complex to engineer. About 100 of the 134 SMR designs in our database are thermal, and 34 are fast spectrum.