# Is Xudabao Unit 1 Nearing Nuclear Island Structural Completion?

A nearly 1,000-tonne steel dome has been hoisted onto the shielded building at Xudabao unit 1 in Liaoning Province, [China National Nuclear Corporation](https://smrintel.com/companies/cnnc) (CNNC) announced on 28 August 2026 — signalling near-completion of the large steel structure modules on China's first CAP1000 unit to begin this construction phase. The outer dome installation follows the inner dome hoist — the top of the [containment structure](https://smrintel.com/glossary/containment) — which took place on 10 February 2026. Together, the two milestones close out what CNNC describes as the foundational steel module campaign for the nuclear island, setting the stage for the next phase of plant system installation.

Xudabao unit 1 is one of two 1,250 MWe CAP1000 reactors licensed in November 2023 by China's National Nuclear Safety Administration. Total investment in units 1 and 2 exceeds CNY 48 billion (approximately USD 6.6 billion), according to CNNC. When all six planned units at the site are complete — a mix of CAP1000 and Russian-supplied VVER-1200 designs — the project is projected to generate nearly 54 billion kilowatt-hours of clean electricity annually.

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## The Dome Itself: Engineering Specifics

The outer dome is conical, not hemispherical — a geometry suited to the CAP1000's passive safety architecture. According to CNNC, it consists of:

- **32 radial main beams**
- **3 ring beams**
- **96 steel cladding panels**
- **3 steel platforms** connected at the bottom

Dimensions: approximately 41 metres in diameter and 11 metres in height, with a total lifting weight of nearly 1,000 tonnes. The structure sits atop a steel-concrete composite shield building and supports the passive containment cooling water storage tank — a defining feature of the AP1000-derived design. In a beyond-design-basis event, gravity drains this tank over the containment vessel exterior, removing decay heat without active pumps or AC power.

The CAP1000 is [Westinghouse Electric Company](https://smrintel.com/companies/westinghouse)'s AP1000 design adapted and domesticated by CNNC for Chinese series construction. Its modular construction philosophy — large steel modules fabricated off-site and lifted into position — is precisely what enables milestones like this to serve as reliable schedule indicators.

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## Timeline and Licensing Context

The Xudabao project has a long and complicated history. Site preparation began in November 2010, and the National Development and Reform Commission approved the project in January 2011 — more than 15 years before this dome lift. The construction licence for units 1 and 2 was issued in November 2023, with a formal ground-breaking ceremony held at the site near Xingcheng City, Huludao, shortly afterward.

The inner dome hoist in February 2026 and now the outer dome hoist in August 2026 represent the two most visible structural completions in the nuclear island construction sequence. CNNC says the outer dome installation "lays a solid foundation for achieving the milestone of the completion of the nuclear island plant structure."

Meanwhile, construction is already underway on units 3 and 4 — two VVER-1200 reactors supplied by [Rosatom State Nuclear Energy Corporation](https://smrintel.com/companies/rosatom). Unit 3 construction began in July 2021, unit 4 in May 2022. Commissioning of those units is scheduled for 2027 and 2028, respectively, meaning VVER units at Xudabao are likely to enter commercial operation before the CAP1000 units do.

Units 5 and 6 — two additional CAP1000 reactors — are proposed but have not yet reached the construction phase.

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## Ownership and Project Structure

Xudabao is owned by Liaoning Nuclear Power Company Ltd, with CNNC holding a 70% stake, Datang International Power Generation Company at 20%, and State Development and Investment Corporation at 10%. China Nuclear Power Engineering Company Ltd, a CNNC subsidiary, serves as general contractor.

This ownership structure is standard for Chinese nuclear projects: a majority state nuclear entity backed by a power generation utility and a state investment vehicle. It provides financing stability but also means project decisions are largely insulated from market signals — a contrast to Western [first-of-a-kind (FOAK)](https://smrintel.com/glossary/foak) projects where capital markets and offtake agreements drive scheduling.

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## What This Means for the Broader Industry

**For CAP1000 series construction:** The Xudabao dome lift is a data point for schedule benchmarking. Chinese series construction of the CAP1000 has matured substantially since the first AP1000 units at Sanmen and Haiyang. The modular approach continues to compress civil construction timelines — relevant context for Western developers still debating whether modular construction can deliver its promised schedule benefits.

**For Westinghouse:** The CAP1000's lineage from the AP1000 remains commercially and technically significant. Every CAP1000 unit that advances demonstrates the underlying passive safety architecture at scale, even if Westinghouse receives no direct revenue from Chinese domestic builds. It also sustains AP1000 operational data that feeds into Westinghouse's own ongoing AP1000 projects and NRC interactions.

**For VVER competition at the same site:** The co-location of CAP1000 and VVER-1200 reactors at Xudabao is analytically interesting. Rosatom's units are scheduled to commission first. If they do, Chinese operators will have direct operational comparison data between the two designs at a single site — [capacity factor](https://smrintel.com/glossary/capacity-factor), maintenance cycles, fuel costs — over the coming decade.

**For the six-unit project economics:** CNNC's stated output of nearly 54 billion kWh annually from all six units, with associated coal displacement of 19.2 million tonnes and CO₂ reduction of 56.7 million tonnes annually, are the project's headline climate figures. Whether those numbers are realised depends on all six units entering commercial operation — units 5 and 6 remain unscheduled.

The outer dome hoist is a construction milestone, not a commissioning one. But in the CAP1000 construction sequence, it marks the transition from heavy civil and steel module work toward mechanical, electrical, and instrumentation installation — the phase where Chinese builders have also been systematically reducing cycle times.

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## Key Takeaways

- **Nearly 1,000-tonne outer dome** hoisted at Xudabao unit 1 on or around 28 August 2026, marking near-completion of large steel structure modules for the nuclear island.
- The conical dome — 41 metres in diameter, 11 metres tall — supports the passive containment cooling water storage tank central to the CAP1000's passive safety system.
- Inner dome was installed on **10 February 2026**; the two hoists together close out the major structural steel campaign.
- Xudabao units 1 and 2 are **1,250 MWe CAP1000** reactors licensed in November 2023; total investment in both units exceeds **CNY 48 billion (USD 6.6 billion)**.
- VVER-1200 units 3 and 4, also under construction at the same site, are scheduled to commission in **2027 and 2028** — ahead of the CAP1000 units.
- All six Xudabao units combined would produce nearly **54 billion kWh annually** and cut CO₂ emissions by **56.7 million tonnes per year**, per CNNC projections.

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## Frequently Asked Questions

**What is the CAP1000 reactor and how does it differ from the AP1000?**
The CAP1000 is China's domesticated version of Westinghouse's AP1000 pressurised water reactor, developed by China National Nuclear Corporation. It retains the AP1000's passive safety systems — including the gravity-fed containment cooling water tank — but incorporates Chinese engineering standards and components. At 1,250 MWe, it is rated similarly to the AP1000.

**What does hoisting the outer dome mean for Xudabao unit 1's construction schedule?**
The outer dome installation marks near-completion of the large steel structure module phase of the nuclear island. CNNC indicated it sets the foundation for achieving completion of the nuclear island plant structure milestone. Construction then transitions toward mechanical, electrical, and instrumentation work — typically a multi-year phase before first criticality.

**Why does Xudabao have both CAP1000 and VVER-1200 reactors?**
The original six-unit plan was entirely CAP1000. Construction of units 3 and 4 later shifted to Russian-supplied VVER-1200 reactors, with construction beginning in 2021 and 2022 respectively. The reasons for the design change are not specified in available sources, but the result is a mixed-design site that will provide comparative operational data.

**Who owns the Xudabao nuclear plant?**
Liaoning Nuclear Power Company Ltd owns the plant. CNNC holds a 70% stake, Datang International Power Generation Company holds 20%, and State Development and Investment Corporation owns 10%. China Nuclear Power Engineering Company Ltd, a CNNC subsidiary, is the general contractor.

**What is the passive containment cooling system on the CAP1000?**
The passive containment cooling system uses a water storage tank positioned above the steel containment vessel. In an emergency, water drains by gravity over the containment exterior, removing decay heat without requiring active pumps or external AC power. The outer dome hoisted at Xudabao unit 1 structurally supports this tank.