Westinghouse Electric Company's AP1000 reactor design is the firstGeneration III+ reactor to receive final design approval from the NRC.[1] It is an evolutionary improvement on the AP600[1]. It is essentially a more powerful model with roughly the same land use.
In the spring of 2007 China National Nuclear Corp. selected the Westinghouse/Shaw consortium to build four nuclear reactors for an estimated US$8 billion, the largest International nuclear contract in history[citation needed].
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[edit]Design specifications
The AP1000 is a two-loop PWR planned to produce a net 1154 MWe. [2] [3] The safety systems apply passive protection, which is designed to yield such a high degree of safety that no emergency diesel generators are required to provide equipment with power in the case that electrical power is lost. In the event of an accident, the AP1000 requires no operator intervention for a significant period of time, which reduces the chance of human error and also allows time for off-site assistance to be mobilized, if required. Safety is also enhanced by using modern, reliable devices. The probability of failures is further decreased by applying several different types of systems. Thus the effect of potential intrinsic failures can be avoided.
The safety systems in the AP1000 are passive, relying on things like gravity and natural recirculation rather than active systems such as pumps. [2] The Passive Core Cooling System (PCCS) is the AP1000's passive analogue to the Emergency Core Cooling System used in currently operating reactors. The PCCS is passive because none of its systems rely on AC power, and the actuation for the safety systems is automatic. The valves required for alignment are usually fail-safe and always powered by energy stored in batteries, springs, or compressed gas. [4]
The design is less expensive to build 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, the AP1000 has:
- 50% fewer safety-related valves
- 35% fewer pumps
- 80% less safety related piping
- 85% less control cable
- 45% less building volume
In December 2005, the Nuclear Regulatory Commission approved the final design certification for the AP1000.[2] This means that prospective builders can apply for a Combined Construction and Operating License (COL) before construction starts, whose validity is conditional upon the plant being built as designed, and that each AP1000 should be virtually identical.
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. (The Nuclear Regulatory Commission is preparing a new safety study, and believes that these plants will be orders of magnitude safer than the last study,NUREG-1150.) The AP1000 has a maximum core damage frequency of 2.41 × 10–7 per plant per year.[5]
The AP1000 will be manufactured in modules designed for rail or barge shipment. This will allow constructing many modules in parallel. The plant is designed to have fuel load 36 months after concrete is first poured. This construction period is much shorter than generation II designs. If achieved, it should greatly decrease the interest costs needed to build the plant. Such reductions would make the design much more economically competitive against other power sources than previous generation nuclear plants.
[edit]Nuclear waste
Nuclear waste produced by the AP1000 can be stored indefinitely in water on the plant site. [6]
[edit]Construction plans
The Chinese units will be the first to be built.
[edit]China
- The Sanmen Nuclear Power Plant in Zhejiang will have at least four units. Site construction for the first two began in February 2008; operation is scheduled for 2013–15.
- The Haiyang Nuclear Power Plant in Shandong also has 2 units planned, with construction started in July 2008, for operation in 2014 or 2015.
China has officially adopted the AP1000 as a standard for inland nuclear projects. The National Development and Reform Commission (NDRC) has already approved several nuclear projects, including the Daban plant in Hubei province, Taohuajiang in Hunan, and Pengze inJiangxi. The NDRC is studying additional projects in Anhui, Jilin and Gansu provinces.[7] China wants to have 100 units under construction and operating by 2020, according to Aris Candris, Westinghouse's CEO.[8]
[edit]USA
As of November 2008, Combined Construction and Operating Licenses (COLs) have been filed for twelve AP1000 reactors in the United States, two each at:[9]
- William States Lee III Nuclear Generating Station in South Carolina,
- Bellefonte Nuclear Generating Station in Alabama,
- Vogtle Electric Generating Plant in Georgia.[10]
- Virgil C. Summer Nuclear Generating Station in South Carolina.[11]
- Levy County Nuclear Power Plant in Florida,
- Shearon Harris Nuclear Power Plant in North Carolina.
On April 9, 2008, Georgia Power Company reached a contract agreement with Westinghouse and Shaw for two AP1000 reactors to be built at Vogtle.[12] The contract represents the first agreement for new nuclear development since the Three Mile Island accident in 1979.[13] The COL for the Vogtle site will be based on the revision 16 to the AP1000 design, which has not yet been approved by the NRC.
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