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The AP1000 is a nuclear power plant designed and sold by Westinghouse Electric Company, now majority owned by Toshiba. The plant is a pressurized water reactor with improved use of passive nuclear safety. In December 2005, the United States Nuclear Regulatory Commission (NRC) approved the final design certification for the AP1000.〔 This meant that prospective US builders could apply for a Combined Construction and Operating License before construction starts, the validity of which is conditional upon the plant being built as designed, and that each AP1000 should be identical. Its design is the first Generation III+ reactor to receive final design approval from the US NRC. In 2008 China started building four units of the AP1000's 2005-design. Aspects of the AP1000 design have been questioned and disputed by senior scientists and engineers including John Ma (of the NRC), Edwin Lyman, and Arnold Gundersen. In December 2011, the NRC approved construction of the first US plant to use the design. On February 9, 2012 the NRC approved the construction of two new reactors. == 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. A design objective was to be less expensive to build than other Generation III designs, by both using existing technology, and needing less equipment than competing three or four cooling loop designs. However, recent AP1000 construction projects in the US, such as Vogtle, and in China, are currently more expensive and are taking longer to build when compared to some other Generation III designs. The design 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 5.09 × 10−7 per plant per year.〔() Westinghouse AP 1000 Step 2 PSA Assessment〕 Used fuel produced by the AP1000 can be stored indefinitely in water on the plant site.〔(Westinghouse certain of safety, efficiency of nuclear power ), ''Pittsburgh Post-Gazette'', March 29, 2009〕 Aged used fuel may also be stored in above-ground dry cask storage, in the same manner as the currently operating fleet of US 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.〔〔R.A. and Worrall, A. “The AP1000 Reactor the Nuclear Renaissance Option.” ''Nuclear Energy'' 2004.〕 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.〔 Revision 15 of the AP1000 design has an unusual containment structure which has received approval by the NRC, after a Safety Evaluation Report,〔(Issued Design Certification - Advanced Passive 1000 (AP1000), Rev. 15 NRC Safety Evaluation Report )〕 and a Design Certification Rule.〔(Issued Design Certification - Advanced Passive 1000 (AP1000), Rev. 15 Design Certification Rule for the AP1000 Design )〕 Revisions 17, 18, and 19 were also approved.〔(Design Certification Application Review - AP1000 Amendment )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「AP1000」の詳細全文を読む スポンサード リンク
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