and introduced the System 80+, with a number of design changes and safety improvements. As part of a series of mergers, purchases, and divestitures by ABB, in 2000 the design was purchased by Westinghouse Electric Company, who had itself been purchased in 1999 by British Nuclear Fuels Ltd (BNFL). Through the 1990s, Westinghouse had been working on a new design known as the AP600 with a design power of about 600 MWe. This was part of the United States Department of Energy’s Advanced Light Water Reactor program that worked on a series of Generation III reactor designs. In contrast to Generation II designs, the AP600 was much simpler, with a huge reduction in the total number of parts, and especially pumps. It was also passively safe, a key feature of Gen III designs. The AP600 was at the small end of the reactor scale. Smaller plants are periodically introduced because they can be used in a wider variety of markets where a larger reactor is simply too powerful to serve the local market. The downside of such designs is that the construction time, and thus cost, does not differ significantly compared to larger designs, so these smaller designs often have less attractive economics. The AP600 addressed this through modular construction and aimed to go from first concrete to fuel load in 36 months. In spite of these attractive features, Westinghouse had no sales of the AP600. With the purchase of the company by BNFL and its merger with ABB, a design combining the features of the System 80+ with the AP600 started as the AP1000. BNFL in turn sold Westinghouse Electric to Toshiba in 2005. AP1000 In December 2005, the Nuclear Regulatory Commission (NRC) approved the final design certification for the AP1000. This meant that prospective US builders could apply for a Combined Construction and Operating License before construction starts, the validity of which is conditional upon the plant being built as designed, and that each AP1000 should be identical. Its design is the first Generation III+ reactor to receive final design approval from the NRC. In 2008 China started building four units of the AP1000's 2005-design. In December 2011, the NRC approved construction of the first US plant to use the design. On February 9, 2012, the NRC approved the construction of two new reactors. In 2016 and 2017 cost overruns constructing AP1000 plants in the U.S. caused Westinghouse's