Containment dome installed at Haiyang 2

Wednesday, 5 August 2015

The top of the containment vessel for unit 2 of the Haiyang nuclear power plant in China's Shandong province was installed yesterday, marking another milestone in the construction of the AP1000.

The dome is lowered into place on Haiyang 2's containment building (Image: SNPTC)

In an operation lasting three-and-a-quarter hours, the containment vessel top head - measuring some 40 meters in diameter, 11.5 meters high and weighing about 790 tonnes - was raised by crane and lowered into place on top of the fourth ring of the containment building. The installation of the containment dome marks the end of general construction works of the unit's nuclear island, State Nuclear Power Technology Corporation (SNPTC) reported.

The containment vessel is a high integrity, freestanding steel structure with a wall thickness of almost 4.5 centimetres. The containment is 39.6 metres in diameter. The ring sections and vessel heads are constructed of steel plates pre-formed in an off-site fabrication facility and shipped to the site for assembly and installation using a large-capacity crane.

The next and final module to be installed will be the containment water tank, which gives the AP1000 its distinctive shape. This large round component is a major part of the AP1000's safety systems. It will hold some 3000 cubic metres of water ready to flow down to evaporate from the surface of the containment vessel in any emergency situation where the reactor system may be overheating. This evaporation would help to cool the overall system. The water could also be directed to top up the used fuel pool, while the tank itself can be refilled from water stored elsewhere on site.

Construction of the Haiyang AP1000s is being managed by Shandong Nuclear Power Company, in collaboration with SNPTC and China Nuclear Energy Construction Corp. SNPTC has a major role in the transfer of knowledge and technology from the plant supplier, Westinghouse.

In addition to the two Westinghouse AP1000 units being built at Haiyang, two more are under construction at the Sanmen site in Zhejiang province. Sanmen unit 1 is expected to be the first AP1000 to begin operating. All four Chinese AP1000s are scheduled to be in operation by 2016.

Four AP1000 reactors are currently being built in the USA - two each at Vogtle and Summer - while three AP1000s are also proposed for the Moorside site in the UK.

Researched and written
by World Nuclear News