X-energy
Xe-100 high-temperature gas-cooled reactor
Ranked #6 in Best Small Modular Reactor Companies.
X-energy, based in Rockville, Maryland and publicly listed, designs the Xe-100, an 80-megawatt high-temperature gas-cooled reactor. Dow's subsidiary Long Mott Energy applied for an NRC construction permit for four Xe-100 units at its Seadrift site in Texas in March 2025.
At a glance
| Price from | Custom |
| Best for | Industrial sites that need both power and process heat |
From X-energy's own website.
What stands out
- Supplies industrial steam as well as power
- Backed by Dow and Amazon
Worth knowing
- Construction permit still under review
- Relies on specialist TRISO fuel
How it ranks
X-energy is ranked 6th of 10 in Best Small Modular Reactor Companies (Lister Score 91.0).
#6 in Best Small Modular Reactor Companies · Lister Score 91.0
The NRC completed its environmental assessment for the Long Mott project in May 2026 with a finding of no significant impact..
| Rank | Best Small Modular Reactor Companies | Score |
|---|---|---|
| 1 | GE Vernova Hitachi Nuclear Energy | 97.2 |
| 2 | NuScale Power | 95.9 |
| 3 | TerraPower | 94.8 |
| 4 | Rolls-Royce SMR | 93.6 |
| 5 | Kairos Power | 92.3 |
| 6 | X-energy | 91.0 |
| 7 | Holtec International | 89.7 |
| 8 | Oklo | 88.3 |
| 9 | Westinghouse | 86.9 |
| 10 | Aalo Atomics | 85.4 |
Frequently asked questions
How does X-energy rank on Lister?
X-energy is ranked 6th of 10 in Best Small Modular Reactor Companies (Lister Score 91.0).
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