Environment & Climate
Governments and private firms increase investments in small modular nuclear reactors
New reactor designs utilizing non-water coolants and factory modularity aim to lower costs, though safety and economic debates continue.
The short version
- Governments and private firms are accelerating investments in small modular reactors (SMRs) to meet growing clean energy demand and lower construction costs.
- Developers are introducing non-light-water technologies, such as TRISO fuel and liquid sodium or molten salt coolants, to operate at lower pressures and improve safety features.
- Critics argue that SMRs may not be more economical than conventional large-scale reactors without high-volume manufacturing, while also citing potential safety risks associated with alternative fuels.
- Key deployment milestones depend on establishing domestic supply chains for high-assay low-enriched uranium fuel and completing ongoing demonstration projects.
Key facts
- Small modular reactors generally produce up to 300 megawatts of electricity, significantly less than the typical 1,000 megawatts generated by standard light-water reactors.[Hacker News]
- The US Department of Energy announced $900 million in grants for SMR deployment in March 2025, while the European Commission announced up to €200 million in SMR investment a year later.[Hacker News]
- Kairos Power began construction on its 50-megawatt Hermes 2 demonstration plant in April and aims to begin commercial operations by 2030 under a power agreement with Google.[Hacker News]
- Kairos Power's Hermes 1 reactor is the first non-light-water design approved by the Nuclear Regulatory Commission in over 50 years, utilizing TRISO pebble fuel and molten salt coolant.[Hacker News]
- TerraPower is developing the 345-megawatt Natrium reactor in Wyoming, using a uranium-zirconium alloy fuel and liquid elemental sodium coolant.[Hacker News]
- TRISO fuel requires high-assay low-enriched uranium enriched to 15–20% uranium-235, prompting the US Department of Energy to award $2.7 billion in January to establish domestic enrichment capacity.[Hacker News]
What remains uncertain
- It remains unverified whether small modular reactors can achieve lower cost-effectiveness than conventional plants, as analysts note factories must manufacture dozens of units to realize economic scale.[Hacker News]
- Safety experts dispute whether alternative SMR fuels and coolants are inherently safer than light-water designs, noting unique material safety challenges.[Hacker News]