Design Specifications
The AP1000 is a two-loop pressurized water reactor planned to produce a net power output of 1,117 MWe. It is an evolutionary improvement on the AP600, essentially a more powerful model with roughly the same footprint.
The design is less expensive to build than other Generation III designs partly because it uses existing technology. The design also decreases the number of components, including pipes, wires, and valves. Standardization and type-licensing should also help reduce the time and cost of construction. Because of its simplified design compared to a Westinghouse generation II PWR, the AP1000 has:
- 50% fewer safety-related valves
- 35% fewer pumps
- 80% less safety related piping
- 85% less control cable
- 45% less seismic building volume
The AP1000 design is considerably more compact in land usage than most existing PWRs, and uses under a fifth of the concrete and rebar reinforcing of older designs.
Probabilistic risk assessment was used in the design of the plants. This enabled minimization of risks, and calculation of the overall safety of the plant. According to the NRC, the plants will be orders of magnitude safer than those in the last study, NUREG-1150. The AP1000 has a maximum core damage frequency of 2.41 × 10−7 per plant per year.
Used fuel produced by the AP1000 can be stored indefinitely in water on the plant site. Aged used fuel may also be stored in above-ground dry cask storage, in the same manner as the currently operating fleet of U.S. power reactors.
Power reactors of this general type continue to produce heat from radioactive decay products even after the main reaction is shut down, so it is necessary to remove this heat to avoid meltdown of the reactor core. In the AP1000, Westinghouse's Passive Core Cooling System uses multiple explosively-operated and DC operated valves which must operate within the first 30 minutes. This is designed to happen even if the reactor operators take no action. The electrical system required for initiating the passive systems doesn't rely on external or diesel power and the valves don't rely on hydraulic or compressed air systems.
The design is intended to passively remove heat for 72 hours, after which its gravity drain water tank must be topped up for as long as cooling is required.
| Date | Milestone |
|---|---|
| January 27, 2006 | NRC issues the final design certification rule (DCR) |
| March 10, 2006 | NRC issues revised FDA for Revision 15 of the Westinghouse design |
| May 26, 2007 | Westinghouse applies to amend the DCR (Revision 16) |
| September 22, 2008 | Westinghouse updated its application |
| October 14, 2008 | Westinghouse provides a corrected set for Revision 17 of the design |
| December 1, 2010 | Westinghouse submits Revision 18 of the design |
| June 13, 2011 | Westinghouse submits Revision 19 of the design |
| December 30, 2011 | NRC issues the final DC amendment final rule |
Revision 15 of the AP1000 design has an unusual containment structure which has received approval by the NRC, after a Safety Evaluation Report, and a Design Certification Rule. Revisions 17, 18, and 19 were also approved
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