Steel security shell bottom installed at Haiyang NPP unit 4

11 July 2023

The containment vessel bottom head (CVBH) for unit 4 of China’s Haiyang NPP in Shandong province has been put in place, marking the official start of construction of the main structure of the nuclear island 40 days ahead of schedule.

The Shanghai Nuclear Engineering Research & Design Institute (SNERDI) said the steel safety shell is an important part of the nuclear island and is the third safety barrier to prevent the leakage of radioactive materials. It is located between the internal structure foundation of the plant and the overall raft base and weighs about 660 tonnes. It is the first of six modules which comprise the steel containment vessel, which when completed will eventually have an inner diameter of 39.62 metres and a height of 65.67 metres.

To ensure the work proceeded smoothly, the Shanghai Nuclear Labor Institute cooperated with participating units on site to sort out the list of prerequisites in advance, and focused on solving various constraints through the coordination day.

The CVBH comprises 64 pre-fabricated arc-shaped steel plates that were assembled and welded on site. It was installed with 16 temporary supporting short columns, studs, mechanical penetrating parts and other items. In an operation lasting just over one-and-a-half hours, with a total hoisting weight of about 756 tonnes, it was hoisted into place using a 3200-tonne crawler crane.

First concrete was poured for the nuclear island of Haiyang 4 in April this year. It marks the official start of construction of the second of two CAP1000 pressurised water reactors - the Chinese version of the AP1000 - planned as Phase II of the plant.

Construction of Haiyang 4 began in April and first concrete was poured for the nuclear island of Haiyang 3 in July 2022. It marked the official start of construction of the first of two CAP1000 pressurised water reactors (the Chinese version of the Westinghouse AP1000) planned as Phase II at the site, where two AP1000 units are already operating. SNERDI noted that the planned construction period for Haiyang 3&4 was 56 months, with both units scheduled to be fully operational in 2027.

Image: The containment vessel bottom head being hoisted into place at Haiyang 4 (courtesy of SNERDI)

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