China poured 6,626 cubic meters of concrete in 62 hours to start Haiyang’s fifth reactor

China’s State Power Investment Corporation moved the Haiyang nuclear plant in Shandong province from site preparation to reactor construction on 31 October, when crews began placing about 6,626 cubic meters of concrete for unit 5. The single pour was planned to run for nearly 62 hours without a break. It is the first safety-related concrete for the plant’s fifth reactor, a CAP1000 pressurized water design.

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A pour of that size is a logistics exercise as much as a construction one. Foundation concrete for a reactor building is normally placed continuously so that fresh batches bond to the ones beneath them, which means mixing plants, truck fleets and placement crews rotate in shifts through the night. Spread over roughly 62 hours, the job averages more than 100 cubic meters of concrete every hour.

The milestone was reported on 2 November by World Nuclear News, which quoted the civil contractor, China Nuclear Industry 24 Construction Co, a subsidiary of China National Nuclear Corporation. The company called the pour the official commencement of the main construction of unit 5 and the start of full-scale work on the site’s third phase. It described the task as a large single pour with a long duration and complex construction organization, and said it relied on experience gained during the first two phases at Haiyang.

A CAP1000 design on a six-unit coastal site

Unit 5 is a CAP1000, China’s localized version of the Westinghouse AP1000. The World Nuclear Association’s reactor entry lists it at 1,161 megawatts net and 1,253 megawatts gross, owned and operated by State Power Investment Corporation, and it shows the same 31 October 2026 construction start. Haiyang is planned as six large pressurized water reactors. Two AP1000 units form the first phase and entered commercial operation in October 2018 and January 2019.

The State Council cleared the third phase on 27 April 2025, at a meeting presided over by Premier Li Qiang. That decision, reported in a World Nuclear News summary of the approvals, covered ten reactors at five sites, with Haiyang units 5 and 6 the only CAP1000 pair among them. The other eight approved units use the Hualong One design, and the five sites involved are Fangchenggang, Haiyang, Sanmen, Taishan and Xiapu. Construction permits for the two Haiyang units came from the National Nuclear Safety Administration. China Daily put the combined investment above 200 billion yuan, about $27.4 billion.

Units 3 and 4 and the 2027 target

The second phase shows what the third will have to match. Haiyang 3 received first safety-related concrete in July 2022, and construction of unit 4 began in April 2025. Both are planned for full operation in 2027 after a 56-month build period. In June 2026, the last large module at unit 4 was lifted into place: the CB20 containment water tank, weighing about 419 tonnes and holding more than 3,000 tonnes of water for emergency cooling, as World Nuclear News described it. The outer steel dome of that unit, about 41 meters across and nearly 1,000 tonnes, had gone up in February, according to its report on the dome lifts.

The water tank is part of the passive safety system. Gravity, natural circulation and compressed gas do the work that pumps and diesel generators do in older designs, and with other passive features the system is meant to hold the plant safe for 72 hours without operator action. Unit 5 inherits that design from the second phase, which is why the contractor stresses lessons carried over from it. The pour therefore tests the civil workforce and the supply chain as much as the reactor technology: the same crews that built the nuclear islands for units 3 and 4 now have to repeat a continuous placement of this scale on a new base mat, with quality records that regulators can audit afterward.

What six reactors would deliver and where China stands

Once units 5 and 6 are finished, the contractor expects the plant to generate 60.9 billion kilowatt-hours a year, enough, by its estimate, for 54 million residents. It also projects about 48.63 million tonnes less carbon dioxide and 18.56 million tonnes of standard coal saved annually, plus district heating capacity above 150 million square meters across 25 county-level cities. Those figures describe the finished six-unit plant, not unit 5 alone, and they are the contractor’s projections. The company says the result would be the world’s largest nuclear energy base to rely entirely on passive pressurized water technology.

Nationally, the World Nuclear Association’s China profile lists 65 operable reactors and 39 under construction. Nuclear produced about 451 terawatt-hours in 2024, roughly 4 percent of China’s total generation of 10,247 terawatt-hours, so the construction pipeline is large against a small current share.

Open questions remain about timing. The report gives the pour’s duration as nearly 62 hours but not its completion time, and neither it nor the association’s entry offers a grid-connection or commercial operation date for unit 5.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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