goingcritical:xe-100-seadriftUnited States · SMR
Long Mott Generating Station (Xe-100, 4 units)
Status: Announced Reactor status full glossary → Announced Publicly announced — a site and design are proposed, but construction has not begun. Site preparation Early site and civil works are under way; the first safety-related ("nuclear") concrete has not yet been poured. Under construction Formal construction has begun, marked by the first nuclear concrete. Fuel loaded Nuclear fuel has been loaded into the core. The reactor is fuelled but has not yet gone critical. Critical Has reached first criticality — a self-sustaining chain reaction, usually at low power — but is not yet connected to the grid. Grid connected Synchronised to the electrical grid and exporting power for the first time, but still in commissioning and power-ascension testing — not yet in commercial service. In commercial operation — the operator has formally declared the unit in regular commercial service. Shut down Permanently shut down and no longer generating; may be defuelled, undergoing decommissioning, or preserved in place. Canceled Abandoned before completion.
Site: Dow UCC Seadrift Operations site, Seadrift, Texas
Lead Xe-100 deployment (DOE ARDP); first NRC construction permit application for a commercial advanced reactor at an industrial (chemical plant) site, supplying Dow with power and process steam
NRC construction permit decision expected Q1 2027 (application docketed May 2025); X-energy expects first commercial delivery in the early 2030s — no stated criticality date
Details
| Design | Xe-100 high-temperature gas-cooled reactor, 4 x 80 MWe |
| Electrical output | 320 MWe |
Milestone history
- Announced May 11, 2023
- Construction start —
- Fuel load —
- First criticality —
- Grid connection —
- Commercial operation —