Maanshan Nuclear Power Plant

Maanshan Nuclear Power Plant
Location of Maanshan Nuclear Power Plant in Taiwan
Official name 馬鞍山核能發電廠
Country Republic of China
Location Hengchun, Pingtung County
Coordinates 21°57′30″N 120°45′5″E / 21.95833°N 120.75139°E / 21.95833; 120.75139Coordinates: 21°57′30″N 120°45′5″E / 21.95833°N 120.75139°E / 21.95833; 120.75139
Status Operational
Commission date
  • 27 July 1984 (Unit 1)
  • 18 May 1985 (Unit 2)

[1]

Decommission date
  • 26 July 2024 (Unit 1, license expiration)
  • 17 May 2025 (Unit 2, license expiration)

[2][3]

Owner(s) Taipower
Operator(s) Taipower
Nuclear power station
Reactor type PWR
Reactor supplier Westinghouse Electric
Fuel type UOX
Power generation
Units operational 2 × 951 MW
Make and model General Electric
Nameplate capacity 1,902 MW

The Maanshan Nuclear Power Plant (馬鞍山核能發電廠 or 核三) is a nuclear power plant located nearby South Bay, Hengchun, Pingtung County, Taiwan. The plant is Taiwan's third nuclear power plant and second-largest in generation capacity. The expected lifespan of this plant is 60 years.[4]

Generation

Each unit at Maanshan is a three-loop Westinghouse PWR with three Westinghouse type F steam generators. Each steam generator has 5626 U-bend tubes made of thermally treated Inconel 600 alloy.[5] The power plant can generate 15 TWh of electricity per year.[6]

Events

1985

On 7 July 1985 a turbine blade failure at Maanshan Unit 1 led to a fire and reactor trip. When the blades failed, the resulting turbine imbalance allowed hydrogen and seal oil to escape from the generator. It took approximately 2 hours for the fire to be extinguished, but no systems critical to safe operation and shutdown were affected. The subsequent repairs were so extensive that Unit 1 did not come back on-line for 11 months.[7] The natural frequency of torsional vibration was 120 Hz, approximately twice that of the electrical frequency, so the resulting resonant vibration led to blade failure.[8]

1988

On 24 September 1988, one control rod assembly was found to be not fully inserted following a reactor trip at Unit 1. Subsequent rod drop tests showed the rod assembly stuck at or above the same not-fully-inserted position, leading to removal and examination of the rod assembly. The examination showed several rods were cracked, which were later determined to result from volumetric growth of the hafnium neutron absorber and differential thermal expansion (hafnium compared to the stainless steel rod cladding). Taipower later replaced all hafnium-containing rods with a different alloy to resolve the issue.[8]

2001

Unit 1 suffered a station blackout on 18 March 2001 when grid instability caused a loss of offsite power and both of the emergency diesel generator trains failed to start. Both units had tripped off-line the prior day due to instability in the 345 kV offsite power transmission line, caused by salt-bearing seasonal sea smog. The 4.16 kV essential bus was transferred to the 161 kV offsite power line, but the 161 kV line was lost soon afterwards. The "A" train emergency diesel generator started but was unable to supply power due to a bus grounding fault, and the "B" train diesel generator lost power to its exciter, resulting in a loss of power to both 4.16 kV essential busses lost power. Service to these busses was not restored for over two hours, when a swing diesel generator (shared between Units 1 and 2) was brought to service.[8]

At the time, this was considered the most notable event in the history of nuclear generation in Taiwan. Neither unit was allowed to restart until the root causes were identified and corrective actions applied, as the same conditions could have occurred at Unit 2.[9]

2005

During the normal full operation of the power plant on 29 January 2005, Unit 2 reactor scram was initiated followed by a main turbine trip. A universal logic card in the plant's solid-state protection system malfunctioned, erroneously reporting a low-low water level condition in the steam generators. This then caused the actuation of the auxiliary feed water system and reactor protection system.[10]

Unit 1 was operating at full power on 25 March 2005 when the reactor tripped on low-low water level in steam generator C.[11] Prior to the trip, the high water level alarm in steam generator C was triggered when the water level kept rising and the main feedwater control valve did not respond to manual intervention. When control of the valve was switched to a backup system, the valve closed immediately, leading to a low-low water level condition in the steam generator before the valve could be re-opened. It was later determined the primary valve positioner had a loose mechanical connection, resulting in erroneous feedback of valve position.[12]

While operating at reduced power in anticipation of typhoon Talim, on 1 September 2005, the Unit 2 main transformer differential protective relay tripped because a damaged support insulator caused one phase to flash to ground. The main transformer trip was followed by main turbine trip and then reactor scram.[13] Following the subsequent repair work, on 8 September 2005, as the unit was in a hot standby condition, a water hammer occurred in one of the main steam lines. It was determined that condensed water accumulated while the unit was in warm standby with the drain valve closed. When that steam line started to supply steam to the turbine, the slug of water was pushed downstream, causing a water hammer and subsequent low steam pressure, resulting in another reactor trip.[14]

2006

Maanshan Nuclear Power Plant was affected by the Hengchun earthquake on 26 December 2006. Because of the vigorous vibration, the alarm at Reactor #2 was activated, forcing the operators to carry out SCRAM immediately. However, Reactor #1 was not affected and remained operational. After the emergency shutdown of Reactor #2, engineers checked the facilities at the plant and no problems had been found.[15][16]

2009

On 12 June 2009 one of the 345 kV startup transformers (which supply station power during refueling outages and reactor startup, and supply backup power to safety-related systems during plant operation) caught fire. Water intrusion into the "B" phase bushing caused an internal arc after high internal oil pressure caused an access handhole to blow out. Since there was a separate and redundant transformer in place, plant operation was not threatened during the 35 minutes it took to extinguish the fire.[17][18]

2010

The Unit 3 of the power plant was shut down on 16 November 2010 to undergo the EOC-19 outage after running in full cycle continuously, safely and stably for 539 days.[19]

2015

One reactor of the plant was shutdown on 27 April 2015 after its auxiliary step-down transformer was caught on fire.[20]

One reactor of the plant will be shut down to undergo an overhaul from 9 November 2015 to 7 December 2015 to replace fuel rods and maintain electrical equipment. The overhaul will also include expanding the DC battery capacity for supplying emergency power for safety equipment from 8 hours to 24 hours.[21]

See also

Wikimedia Commons has media related to Maanshan Nuclear Power Plant.

References

  1. ↑ "Maanshan Nuclear Power Plant Taiwan - GEO". Globalenergyobservatory.org. 2010-02-15. Retrieved 2014-05-01.
  2. ↑ "Taiwan Nuclear Power". World-nuclear.org. Retrieved 2014-05-01.
  3. ↑ "Design Features of Nuclear Power Plants". Atomic Energy Council. Retrieved December 3, 2014.
  4. ↑ "Maanshan Nuclear Power Plant Unit 1 Reactor | Operation and Structual [sic] Details". Nuclear-power-plants.findthedata.org. Retrieved 2014-05-01.
  5. ↑ Maanshan Unit 2 Steam Generator Water Level Oscillation and Cleaning (PDF) (Technical report). Atomic Energy Council, Department of Nuclear Regulation. May 31, 2005. Retrieved 4 December 2014.
  6. ↑ "Taipower mulls extending use of three nuclear plants". Taipei Times. CNA. 2014-04-24. Retrieved 2014-05-01.
  7. ↑ Nowlen, S.P.; Kazarians, Dr M.; Wyant, F. (August 2001). Risk Methods Insights Gained from Fire Incidents (PDF) (Technical report). US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. pp. A12–1, A12–2. NUREG/CR-6738; SAND2001-1676P. Retrieved 8 December 2014.
  8. 1 2 3 "Article 6. Existing Nuclear Installations". The Republic of China National Report for the Convention on Nuclear Safety (PDF) (Technical report). Atomic Energy Council. September 2004. pp. 6–5 to 6–7. Retrieved 18 December 2014.
  9. ↑ The Station Blackout Incident of the Maanshan NPP unit 1 (PDF) (Report). Atomic Energy Council. 18 April 2001. Retrieved 3 December 2014.
  10. ↑ RER-94-32-001: Reportable Event Report on Maanshan Nuclear Power Plant Unit 2 Steam Generator Low-Low Level Scram (PDF) (Report). Retrieved 3 December 2014.
  11. ↑ RER-94-31-001: Reportable Event Report on Maanshan Nuclear Power Plant Unit 1 Reactor Scram Arising from the Low-Low Water Level of Steam Generator (PDF) (Report). Retrieved 7 December 2014.
  12. ↑ Chen, Pu-Tsan (2005). Recent Significant Events (PDF) (Technical report). Taiwan Power Company. Retrieved 4 December 2014.
  13. ↑ RER-94-32-002: Reportable Event Report on Maanshan Nuclear Power Plant Unit 2 Reactor Scram Incident (PDF) (Report). Retrieved 3 December 2014.
  14. ↑ RER-94-32-003: Reportable Event Report on Maanshan Nuclear Power Plant Unit 2 September 8 Main Steam Line Low Pressure Incident that Triggered the Actuation of the Main Steam Isolation and Feed Water Isolation, and the Reactor Trip Signal (PDF) (Report). Retrieved 3 December 2014.
  15. ↑ 台湾核电厂紧急停机, Phoenix Television website, 2006-12-27(Chinese)
  16. ↑ Hsu, M.T. (June 21, 2007). The Effect of Maanshan NPS Due to the Earthquake Occurred on December 26, 2006 (PDF) (Technical report). Atomic Energy Council, Department of Nuclear Regulation. Retrieved 4 December 2014.
  17. ↑ 345kV Startup Transformer Failure (June 12 2009 Mannshan NPP) (PDF) (Technical report). Taiwan Power Company, Department of Nuclear Generation. April 2010. Retrieved 18 December 2014.
  18. ↑ "Article 6. Existing Nuclear Installations". The Republic of China National Report for the Convention on Nuclear Safety (PDF) (Technical report). Atomic Energy Council. September 2010. pp. 21–26. Retrieved 18 December 2014.
  19. ↑ "Taiwan power company-Taipower Events". Taipower.com.tw. Retrieved 2014-06-03.
  20. ↑ http://focustaiwan.tw/news/asoc/201504270010.aspx
  21. ↑ http://focustaiwan.tw/news/aeco/201511050043.aspx
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