The AP originally stood for Advanced Passive reactor, stemming from its revolutionary design. First built as the AP600 (with 600MW electrical power), Westinghouse subsequently upgraded the design to 1,000MW (hence AP1000), after no sales were achieved. Here we track the AP build in the US.
Why is the AP1000 both evolutionary and revolutionary? Evolutionary, because it uses tried and tested components, some that have been in use for decades. But revolutionary because of its design, which uses advanced passive technology to produce a far simpler safety system to operate in the event of an accident. The AP1000 is also far smaller than many comparable Gen II reactors and is designed to be easier to operate and need less maintenance.
The AP600 was the first reactor to eliminate the need for active safety systems (and AC power) to handle a complete, Fukushima-type blackout. The emergency backup diesel generators were no longer needed, although two safety-related generators were included for general use.
The AP1000 reactor is a two-loop Pressurised Water Reactor (PWR), designed for new baseload generation. It delivers a gross power rating of 3,415 megawatts thermal (MWth) and a nominal net electrical output of approximately 1,200 megawatt electric (MWe).
The following three sections have been taken from the AP1000 fact sheet.
Advanced Passive technology
A unique feature of the AP1000 plant is its use of natural forces—such as natural circulation, gravity and convection—to operate in the highly unlikely event of an accident, rather than having to rely on operator actions and AC power.
Even with no operator actions and a complete loss of all on-site and off-site AC power (Station Blackout), as was the case in the Fukushima disaster, the AP1000 plant will safely shut down and remain cool.
The AP1000 plant has a 72-hour Coping Period following a Station Blackout, meaning that it cools itself down and remains safe for three days without any AC power or operator actions required. Following this 72-hour period, additional water supplies and resources on-site can be utilised by the operator to maintain core and containment cooling indefinitely.
To illustrate the passive nature of these safety systems, the containment cooling system of the AP1000 plant is shown in Figure 1. [Please fill in the form to continue reading.]
