Cernavodă Nuclear Units 3 and 4 Completion, Cernavodă

Two reactor buildings at Cernavodă have stood unfinished since 1989, when work stopped with the fall of Nicolae Ceaușescu. Romania is now paying to finish them. The Cernavodă Units 3 and 4 completion project will add two CANDU 6 units of about 650 MWe each to the plant on the Danube-Black Sea Canal, owned by state utility Nuclearelectrica through its project company EnergoNuclear.

The engineering, procurement and construction management contract was signed on November 15, 2024, at COP29 in Baku. It’s worth €3.2 billion (about $3.4 billion) and went to FCSA, a joint venture of Fluor, AtkinsRéalis subsidiary Candu Energy, Ansaldo Nucleare and Sargent & Lundy.

Project Scope

In 2021, Nuclearelectrica put Unit 3 at 52% complete and Unit 4 at 30%. That’s mostly civil work: the containment structures and turbine hall steel that are still visible from the site roads. Everything inside has to be engineered, procured and installed to a current CANDU 6 design and a current licensing basis. The European Commission issued a positive opinion on the project in July 2024.

The contract runs in two stages. Phase 1 is a limited notice to proceed lasting 24 to 30 months, covering engineering, licensing support and early procurement. Phase 2, the final notice to proceed, runs 80 to 84 months and depends on a final investment decision. Nuclearelectrica is targeting commercial operation in 2030 for Unit 3 and 2031 for Unit 4.

Financing leans on export credit agencies from the contractors’ home countries. Announced support includes $3 billion from US EXIM and €2 billion from Italy, plus Canadian export financing. In September 2025 Nuclearelectrica signed an €80 million bank loan for the units, led by J.P. Morgan, alongside €540 million for the separate Unit 1 refurbishment.

Why It Matters

Finishing a half-built reactor isn’t the same job as building a new one. The concrete is more than 35 years old and has to be assessed, documented and in places repaired before anyone sets equipment against it. That’s where FCSA’s split makes sense. Candu Energy owns the reactor design, and the two U.S. firms bring EPCM management and nuclear engineering depth to a job that’s part inspection, part construction.

The schedule is tight on a busy site. Cernavodă’s two operating units already supply about a fifth of Romania’s electricity, and Unit 1 comes offline for refurbishment from 2027 to 2029, right as Units 3 and 4 should be moving into heavy construction. One owner, one site, two major nuclear programs running at once. If both land on time, the plant roughly doubles its output by 2031.

Project Team & Details