The plant is a pressurized water reactor with improved use of passive nuclear safety. It is a generation 3.5 reactor
Because of its simplified design compared to a Westinghouse generation II PWR, the AP1000 has:
50% fewer safety-related valves
35% fewer pumps
80% less safety-related piping
85% less control cable
45% less seismic building volume
It has a core cooling system including passive residual heat removal by convection, improved containment isolation, passive containment cooling system to the atmosphere and in-vessel retention of core damage (corium) with water cooling around it. No safety-related pumps or ventilation systems are needed
In 2008 and 2009, Westinghouse made agreements to work with the Chinese State Nuclear Power Technology Corporation (SNPTC) and other institutes to develop a larger design, the CAP1400 of 1,400 MWe capacity, possibly followed by a 1,700 MWe design. China will own the intellectual property rights for these larger designs. Exporting the new larger units may be possible with Westinghouse's cooperation
Westinghouse has been working with SNPTC and SNERDI in China to develop jointly a passively safe 1500 MWe (4040 MWt) two-loop design from the AP1000, the CAP1400, with 193 fuel assemblies and improved steam generators, operating at 323°C outlet temperature, 60-year design life, and 72-hour non-intervention period in event of accident. Average discharge burn-up is about 50 GWd/t, maximum 59.5 GWd/t. Operation flexibility includes MOX capacity, 18 to 24-month cycle, and load-following. Seismic rating is 300 gal. The CAP1400 project may extend to a larger, three-loop CAP1700 or CAP 2100 design if the passive cooling system can be scaled to that level
In November 2015 SNPTC said that CAP1400 construction would start on 31 March 2016, the delay being to ensure that the primary coolant pump issues on AP1000 were sorted and to avoid winter conditions for the major concrete pour. It is expected to take 56 months to build, with later units coming down to 50 months. Westinghouse is providing technical consulting services to SNPTC for the design. More than 80% of the components will be indigenous, and contracts for 21 of 29 long lead time components had been signed by February 2015. Construction cost is expected to be CNY 15,751/kWe ($2454/kWe) and power cost CNY 0.403/kWh for the first unit and dropping to CNY 0.38/kWh (USD 5.9 cents) subsequently. A 2014 government figure is CNY 42.3 billion ($6.5 billion) for the first two units.
In September 2007, Westinghouse and its partners the Shaw Group received authorization to construct four AP1000 units in China: two at Sanmen in Zhejiang province and two more at Haiyang.
Sanmen unit 1 is expected to be the first AP1000 to begin operating later this year, while Haiyang 1 is also expected to start up by the end of the year.
SNPTC announced last month that the four main pumps at Sanmen 1 had been operated continuously at full speed for five hours as part of the unit's start-up. The company said that, at full-speed, the pumps' vibration, stator temperature and bearing temperature were within the normal range.
Four AP1000 reactors are being built in the USA - two each at Vogtle and Summer - while three AP1000s are also proposed for the Moorside site in the UK.
SOURCES- World Nuclear Association, Wikipedia, World Nuclear news