The fact that the AP600 could not compete with natural gas meant that Westinghouse's engineers needed to get more power out of the design while cutting costs.
The result is a reactor similar to the AP600 that delivers almost twice as much power.
The fact that the AP600 had already been licensed in 1999 speeded up the approval of the AP1000 in the US because of the many similarities between the two.
NRC's Gary Holahan acknowledges that the agency relied on the tests from the AP600
and computer modeling for the AP1000, but says that after extensive review by the commission's technical staff and the Advisory Committee on Reactor Safeguards, it determined that additional testing was not necessary.
Adrian Bull, UK stakeholder relations manager for Westinghouse, says the challenge for the company was to take the design of the AP600 and squeeze double the power out of it.
There were modifications to the height of the reactor core but the footprint of the AP1000 is basically the same as that of its less powerful cousin, the AP600.
The AP1000 uses fewer components than current reactors, in common with the AP600, in itself a "novel design in terms of its reduction in complexity, says Bull.
According to Westinghouse, the design of the AP600 requires 50 percent fewer valves, 80 percent less safety grade piping, 70 percent less control cable, 35 percent fewer pumps (with no safety grade pumps), and 45 percent less seismic building volume than other conventional reactors.
The AP600 is designed to go up in three years, the pebble bed reactor in two.
Prefabricated sections of this plant will be shipped and assembled on-site so construction can be completed within three years, from ground breaking to initial fuel load, according to Robert Vijuk, project manager for AP600 Design Certification.
Because of its modular design, the AP600 can be built in parallel steps rather than sequentially, which is the traditional way.
Westinghouse engineers simplified the nuclear island of their AP600 so that it now uses 50 percent fewer valves, 80 percent less piping, and 70 percent less cable than the conventional midsize nuclear power plant.