goingcritical:mochovce-4Slovakia · Power reactor
Mochovce-4
Status: Grid connected critical since August 6, 2026 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: Mochovce, Nitra Region
Final unit of a project begun in 1987; sister unit Mochovce 3 started up in 2023
Details
| Design | VVER-440/V-213 |
| Electrical output | 440 MWe |
Milestone history
- Announced —
- Construction start January 1987
- Fuel load June 29, 2026
- First criticality August 6, 2026
- Grid connection October 15, 2026
- Commercial operation —
References
- WNN, fuel loading began at Mochovce 4, 29 June 2026
- WNN, fuel loading completed 3 July 2026
- Slovak Nuclear Regulatory Authority, commissioning of Mochovce 4 has begun
- CEE Energy News - Slovakia reaches milestone at Mochovce Nuclear Plant
- ÚJD SR (Slovak nuclear regulator), 7 Aug 2026 — "dosiahol vo štvrtok 6. augusta 2026 o 22.10 h prvý kritický stav reaktora"; minimum controlled power 22:31
- Slovenské elektrárne press release (7 Aug 2026) — reactor critical at 22:10 CEST on Thursday 6 August 2026, minimum controlled power 22:31
- WNN, First criticality for Mochovce 4 (10 Aug 2026) — quotes the operator: landmarks at 22:10 and 22:31 on Thursday 6 August
- World Nuclear News: Mochovce 4 connected to the grid