Where advanced reactors actually stand
What does "Contested / actively debated" mean?
A real, mainstream scientific or policy debate exists. Reasonable experts disagree. — New editorial status update written for this rebuild; archive coverage thins after ~2022.
A current, honest scorecard of the leading advanced-reactor programs — what's funded, what's under construction, and what's still on the drawing board — as of 2025.
In one lineReal money and construction for the first time in a generation.
Editor's note on sources & how this was curated
New editorial status update written for this rebuild; archive coverage thins after ~2022.
Atomic Insights explainer
New · written for this rebuildWhy a scorecard
The advanced-reactor field moves fast and is full of optimistic press releases. Here's a grounded snapshot as of 2025 — exciting, but with the hype filtered out. CONTESTED timelines and costs below are best-available estimates and routinely slip.
The leaders
- TerraPower (Natrium) — sodium fast reactor with molten-salt heat storage. Construction of non-nuclear facilities began in Wyoming (2024); fuel (HALEU) supply is the key risk.
- X-energy (Xe-100) — high-temperature gas/TRISO reactor, paired with Dow for industrial heat in Texas.
- Kairos Power (Hermes) — fluoride-salt-cooled demonstrator under construction in Tennessee; a low-power Hermes unit is the near-term milestone.
- Oklo (Aurora) — sodium-cooled microreactor; pursuing a combined license after an earlier NRC denial.
- NuScale — design certified by the NRC, but its flagship UAMPS deployment was cancelled in 2023; still seeking new customers.
- GE Hitachi (BWRX-300) — a simplified SMR based on proven boiling-water technology; Ontario's Darlington is a lead project.
The honest bottom line
SETTLED real money, real licensing progress, and real construction are happening for the first time in a generation. CONTESTED whether these translate into on-time, on-budget commercial fleets is still unproven — first-of-a-kind risk is real. The direction is genuinely encouraging; the timelines deserve healthy skepticism.
What's the honest status of advanced reactors in 2025?
- ✓TerraPower, X-energy, Kairos, Oklo are leading the wave.
- ✓Licensing progress and real construction are underway.
- ✓On-time, on-budget commercial fleets are still unproven.
✓ Active recall
1. What makes a reactor a 'small modular reactor'?
2. What is the commercial status of molten-salt/thorium (LFTR) reactors?