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AP600 Design Objectives The primary design objective of the AP600 was to provide a greatly simplified plant design that meets NRC regulatory requirements, meets or exceeds NRC safety goals and those of the ALWR Utility Requirements Document, and addresses past safety issues, while being economically competitive with other power generation systems over the full operating cycle. This objective is to be met using experience-based components so that plant prototype or demonstration models are not required. Simplification of plant systems, combined with increased plant operating margins, reduces the actions required by the operator in the event of an accident. The AP600 design requires no operator actions to maintain a safe configuration following a design basis accident. The design target for the AP600 is to technically support elimination of the emergency planning zone beyond the site boundary. Simpler systems, combined with the U.S. licensing reforms of 10CFR52, increase the licensing certainty of the AP600 in international markets. Implementation of the passive safety features greatly reduces the operation, maintenance and testing requirements of the AP600. The AP600 has been designed to have a shorter construction schedule through the use of modular construction techniques that are similar to those applied in ship construction. The construction design objective is a 36-month schedule from first concrete pour to the fuel load. An added benefit of this approach is that a significant portion of the quality assurance inspections can be completed in the factory before the modules are delivered to the construction site. Passive Safety Features Overview The AP600 uses passive safety systems to enhance the safety of the plant and to satisfy NRC safety criteria. These systems use only natural forces, such as gravity, natural circulation, and compressed gas. No pumps, fans, diesels, chillers, or other rotating machinery are used in the passive safety sub-systems. A few simple valves are used to align the passive safety systems when they are automatically actuated. In most cases these valves are "fail safe" (i.e., they require power to stay in their normal, closed position; loss of that power causes them to open to their safety alignment. This power is normally supplied by class lE uninterruptible power supplies). These passive safety systems are significantly simpler than typical PWR safety systems. In addition to being simpler, the passive safety systems do not require the large network of safety support systems needed in typical nuclear plants, such as AC power, HVAC (heating, ventilating, air conditioning) and cooling water systems and seismic buildings to house these components. This simplification includes eliminating the safety-grade emergency diesel generators and their network of support systems, air start, fuel storage tanks and transfer pumps, and the air intake/exhaust system. As a result, support systems no longer need to be safety grade and can be simplified or eliminated. The features of the AP600 passive safety systems include passive safety injection, passive residual heat removal, and passive containment cooling. All these passive systems have been designed to meet the NRC single-failure criteria and its recent criteria, including TMI lessons-learned and unresolved and generic safety issues. PRAs have also been used to quantify the safety of the design. Passive Core Cooling System See the Core Cooling link for details of the AP600 passive core cooling system. Passive Containment Cooling System See the Containment Cooling link for details of the AP600 passive containment cooling system.
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