Although the AP600 uses simplified and passive plant systems to an unprecedented extent to enhance plant safety and operations, the effectiveness of the technology has been demonstrated through years of operations and testing. The AP600's major components are based on years of reliable operating experience. The canned motor reactor coolant pumps have been in use by the US Navy for decades. The steam generators, pressurizer, fuel, and reactor vessel are all based on field-proven technology with incremental improvements developed as a result of operating experience. The passive safety systems are an extension of the technology used previously, since Westinghouse-supplied PWRs have had accumulators for injection of core cooling water without the use of pumps for many years. The AP600 is the result of a logical progression in plant design.