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AP1000

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Computer generated image of AP1000

Westinghouse Electric Company's AP1000 reactor design is the first Generation III+ reactor to receive final design approval from the U.S. Nuclear Regulatory Commission (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. As of April 2010, these are the only units in the world to have started construction.

The NRC questioned the durability of the AP1000 reactor's original shield building in the face of severe external events such as earthquakes, hurricanes, and airplane collisions. Therefore, Westinghouse modified the design.[2] A US nuclear consultant engineer has also criticized the AP1000 containment design arguing that, in the case of a design-basis accident, it could release radiation; Westinghouse has denied the claim.[3] The NRC anticipates completing the overall design certification review for the AP1000 around September 2011.[2]

Design specifications

File:AP600PassiveContainment.jpg
Diagram of AP600/AP1000 passive safety systems

The AP1000 is a two-loop PWR planned to produce a net 1154 MWe. [4] [5]

The design is less expensive to build than other Gen III plants 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:[6]

  • 50% fewer safety-related valves
  • 35% fewer pumps
  • 80% less safety related piping
  • 85% less control cable
  • 45% less seismic building volume

The 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.[6]

In December 2005, the NRC approved the final design certification for the AP1000.[4] 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.[7]

Passive Core Cooling System

Power reactors of this general type continue to produce heat from radioactive decay products even after the main reaction is shut down, so it's necessary to remove this heat to avoid meltdown of the reactor core and possible escape into the containment or, worse, beyond the containment. In this design Westinghouse's Passive Core Cooling System (PXS) uses less than twenty 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.[8] 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.[4][9]

If the active process to turn on the passive system works the design is intended to passively remove heat for 72 hours, after which the Passive Containment Cooling System (PCS) gravity drain water tank must be topped up for as long as cooling is required.

Safety concerns

The AP1000 design has an unusual containment structure, but the Nuclear Regulatory Commission has approved it, after Safety Evaluation Reports,[10] and after a Design Certification Rule.[11] The Westinghouse-proposed amendment of AP1000 has been approved up to Revision 17, and it is under way for Revision 18.[12]

In April 2010, Arnold Gundersen, a nuclear engineer commissioned by several anti-nuclear groups, released a report which explored a hazard associated with the possible rusting through of the containment structure steel liner. In the AP1000 design, the liner and the concrete are separated, and if the steel rusts through, "there is no backup containment behind it" according to Gundersen.[13] If the dome rusted through the design would expel radioactive contaminants and the plant "could deliver a dose of radiation to the public that is 10 times higher than the N.R.C. limit" according to Gundersen. Vaughn Gilbert, a spokesman for Westinghouse, has disputed Gundersen’s assessment, stating that the AP1000's steel containment vessel is three-and-a-half to five times thicker than the liners used in current designs, and that corrosion would be readily apparent during routine inspection.[13]

Nuclear waste

Used fuel produced by the AP1000 can be stored indefinitely in water on the plant site.[14] 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.[6]

Construction plans

The Chinese units will be the first to be built.[6]

China

Chinese undergoing training for the AP1000 reactor. The first four units will be built in China.

The first four AP1000s built are to an earlier revision of the design without a strengthened containment structure to provide improved protection against an air crash.[15]

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 Dafan plant in Hubei province, Taohuajiang in Hunan, and Pengze in Jiangxi. The NDRC is studying additional projects in Anhui, Jilin and Gansu provinces.[16] China wants to have 100 units under construction and operating by 2020, according to Aris Candris, Westinghouse's CEO.[17]

CAP1400 development

In 2008 and 2009 Westinghouse made agreements to work with the State Nuclear Power Technology Corporation (SNPTC) and other institutes to develop a larger design, probably of 1400 MWe capacity, possibly followed by a 1700 MWe design. China will own the intellectual property rights for these larger designs. Exporting the new larger units may be possible with Westinghouse's cooperation.[18]

In December 2009, a Chinese joint venture was set up to build an initial CAP1400 near the HTR-10 Shidaowan site. Construction is expected to start in 2013, operating in 2017.[18]

USA

As of January 2010, applications for Combined Construction and Operating Licenses (COLs) have been filed for fourteen AP1000 reactors in the United States, two each at:[19]

On April 9, 2008, Georgia Power Company reached a contract agreement with Westinghouse and Shaw for two AP1000 reactors to be built at Vogtle.[23] The contract represents the first agreement for new nuclear development since the Three Mile Island accident in 1979.[24] The COL for the Vogtle site is to be based on the revision 18 to the AP1000 design.[25] On February 16, 2010, President Obama announced $8.33 billion dollars in federal loan guarantees to construct the two AP1000 units at the Vogtle plant.[26]

Environmental groups opposed to the licensing of the two new AP1000 reactors to be built at Vogtle filed a new petition in April 2011 asking the Nuclear Regulatory Commission's commission to suspend the licensing process until more is known about the evolving Fukushima I nuclear accidents.[27]

See also

References

  1. ^ a b "AP 1000 Public Safety and Licensing". Westinghouse. 2004-09-13. Archived from the original (web) on 2007-08-07. Retrieved 2008-01-21.
  2. ^ a b Robynne Boyd. Safety Concerns Have Delayed Approval of First U.S. Nuclear Reactor in Decades Scientific American, July 29, 2010.
  3. ^ AP1000 containment insufficient for DBA, engineer claims Nuclear Engineering International, 29 April 2010.
  4. ^ a b c T.L. Schulz. "Westinghouse AP1000 advanced passive plant" (web). Nuclear Engineering and Design; Volume 236, Issues 14–16, August 2006, Pages 1547–1557; 13th International Conference on Nuclear Energy, 13th International Conference on Nuclear Energy. ScienceDirect. Retrieved 2008-01-21. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help); Italic or bold markup not allowed in: |work= (help)
  5. ^ Contact;Tom Murphy. "New Reactor Designs" (web). Article summarizes nuclear reactor designs that are either available or anticipated to become available in the United States by 2030. Energy Information Administration (EIA). Retrieved 2008-01-21.{{cite web}}: CS1 maint: multiple names: authors list (link)
  6. ^ a b c d Adrian Bull (16 November 2010), "The AP1000 Nuclear Power Plant - Global Experience and UK Prospects" (presentation), Westinghouse UK, Nuclear Institute, retrieved 14 May 2011
  7. ^ [1] Westinghouse AP1000 PRA Summary
  8. ^ "UK AP1000 Pre-Construction Safety Report" (web). UKP-GW-GL-732 Revision 2 explains the design of the reactor safety systems as part of the process of seeking approval for construction in the UK. Westinghouse Electric Company. Retrieved 2010-02-23.
  9. ^ R.A. and Worrall, A. “The AP1000 Reactor the Nuclear Renaissance Option.” Nuclear Energy 2004.
  10. ^ Issued Design Certification - Advanced Passive 1000 (AP1000), Rev. 15 NRC Safety Evaluation Report
  11. ^ Issued Design Certification - Advanced Passive 1000 (AP1000), Rev. 15 Design Certification Rule for the AP1000 Design
  12. ^ Design Certification Application Review - AP1000 Amendment
  13. ^ a b Matthew L. Wald. Critics Challenge Safety of New Reactor Design New York Times, April 22, 2010.
  14. ^ Westinghouse certain of safety, efficiency of nuclear power, Pittsburgh Post-Gazette, March 29, 2009
  15. ^ Mark Hibbs (April 27, 2010), "Pakistan Deal Signals China's Growing Nuclear Assertiveness", Nuclear Energy Brief, Carnegie Endowment for International Peace, retrieved 25 February 2011
  16. ^ Li Qiyan (September 11, 2008). "U.S. Technology Picked for Nuclear Plants". Caijing. Retrieved 2008-10-29.
  17. ^ Pfister, Bonnie (2008-06-28). "China wants 100 Westinghouse reactors". Pittsburgh Tribune-Review. Retrieved 2008-10-29.
  18. ^ a b "Nuclear Power in China". World Nuclear Association. 2 July 2010. Retrieved 18 July 2010.
  19. ^ "Combined License Applications for New Reactors". U.S. Nuclear Regulatory Commission (NRC). January 4, 2010. Retrieved 2010-02-03.
  20. ^ "Virgil C. Summer Nuclear Site, Units 2 and 3 Application". March 27, 2008. Retrieved 2008-12-01.
  21. ^ "China Selects Westinghouse AP1000 Nuclear Power Technology". Westinghouse Electric Company. December 16, 2007. Retrieved 2008-06-15.
  22. ^ "Turkey Point, Units 6 and 7 Application". NRC. June 30, 2008. Retrieved 2010-02-03.,
  23. ^ Terry Macalister (10 April 2008). "Westinghouse wins first US nuclear deal in 30 years". The Guardian. Retrieved 2008-04-09.
  24. ^ "Georgia Power to Expand Nuclear Plant". Associated Press. Archived from the original on 2008-04-13. Retrieved 2008-04-09.
  25. ^ "NRC: Combined License Application Documents for Vogtle, Units 3 and 4 Application". NRC. Retrieved 2011-03-11.
  26. ^ "Obama Administration Announces Loan Guarantees to Construct New Nuclear Power Reactors in Georgia". The White House Office of the Press Secretary. Retrieved 2010-04-30.
  27. ^ Rob Pavey (April 6, 2011). "Groups want licensing of reactors suspended". Augusta Chronicle.

External links


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