Pickering Nuclear Generating Station

Pickering Nuclear Generating Station

A unit at the Pickering plant
Location of Pickering Nuclear Generating Station in Ontario
Country Canada
Location Pickering, Durham Region, Ontario
Coordinates 43°48′42″N 79°03′57″W / 43.81167°N 79.06583°W / 43.81167; -79.06583Coordinates: 43°48′42″N 79°03′57″W / 43.81167°N 79.06583°W / 43.81167; -79.06583
Status Operational
Construction began 1966
Commission date 1971-73 (A station)
1983-86 (B station)
Decommission date 1997 (Units A2 and A3) Permanently shutdown and defuelled, but NOT yet decommissioned.
Owner(s) Ontario Power Generation (OPG)
Nuclear power station
Reactor type CANDU
Thermal power station
Cooling source Lake Ontario
Power generation
Units operational 4× 516 MW
2× 515 MW
Units decommissioned 2× 515 MW
Nameplate capacity 3,252 MW
Website
OPG - Pickering Nuclear

Pickering Nuclear Generating Station is a Canadian nuclear power station located on the north shore of Lake Ontario in Pickering, Ontario. The facility derives its name from the City (originally Township) of Pickering in which it is located. It produces 15-20% of Ontario's power and employs 3,000 workers.[1]

Co-located at the Pickering station is a single 1.8 MWe wind turbine named the OPG 7 commemorative turbine.

Reactor classification

The reactors can be classified as follows:

PICKERING A

PICKERING B

Construction

The facility was constructed in stages between 1966 and 1986 by the provincial Crown corporation, Ontario Hydro. In April 1999, Ontario Hydro was split into five component Crown corporations with Ontario Power Generation (OPG) taking over all electrical generating stations and which continues to operate the Pickering station.

The Pickering station is one of the largest nuclear facilities in the world and comprises eight CANDU nuclear reactors located on the northern shore of Lake Ontario, having a total output of 4124 MW (capacity net) and 4336 MW (gross net) when all units are on line. Pickering is only surpassed in Canada by the Bruce Nuclear Generating Station, which while also having 8 reactors, has a greater output. The facility is connected to the North American power grid via numerous 230,000 and 500,000-volt transmission lines.

The facility was operated as two distinct stations, Pickering A (Units 1 to 4) and Pickering B (Units 5 to 8) until 2011. While primarily administrative in nature, the division was not wholly artificial, as there are some distinct differences in design between the two groups of stations. (Example: The Pickering A units employ moderator dump as a shutdown mechanism, a feature not found in Pickering B.) There are, however, a number of systems and structures in common between the two stations; the most notable of these is possibly the shared vacuum building, a negative pressure containment system. The operation of Pickering A and B is being unified in order to reduce costs now that Pickering Units 2 and 3 are shut down in safe storage.

Partial shutdown

On December 31, 1997 the four Pickering A reactors were shut down by Ontario Hydro and placed in lay up, suspending work on upgrades to the shutdown system. As a result, the federal regulator, the Atomic Energy Control Board, because of the decision to delay the upgrade of the emergency shutdown systems at the station, required the corporation to obtain regulatory approval before restarting the units.[2] Ontario Hydro committed to restarting the units, but the project underwent long delays and large cost over-runs.

Premier Mike Harris asked former federal energy Minister Jake Epp to study and make recommendations on the problems with the Pickering restart. Mr. Epp acknowledged the large cost over-runs and delays attributing blame to bad management. The Epp Review estimated the cost of restarting the remaining reactors at $3 – 4 billion and supported the continuation of the project.

Upon election in 2003 the government of Dalton McGuinty was not immediately prepared to proceed with the restart of Pickering A. On December 16, 2003 the McGuinty government tasked the Ontario Power Generation Review Committee with reviewing the structure of Ontario Power Generation and the restart of the Pickering A reactors. The Committee included former federal finance Minister John Manley as chair as well as Peter Godsoe, a former CEO of Scotiabank, and Jake Epp.

On March 18, 2004 the OPG Review Committee released its report, attributing the blame for cost over-runs to bad management. The report recommended proceeding with the restart of the Pickering “A” reactors, bringing unit 1, 2, and 3 online sequentially. The report suggested that the restart of units 2 and 3 should be contingent as to whether “OPG will be able to succeed at the Unit 1 project.”[3]

The anti-nuclear group Sierra Club of Canada criticized the report for not attributing any blame to the problems of nuclear technology, noting that there were no energy or environmental experts appointed to the panel.[4]

Numerous changes in executive-level staff and project management strategy were made for the follow-on project to refurbish Unit 1. The experience of refurbishing Pickering A Unit 1 was significantly different from Unit 4, with a much tighter adherence to schedule and budget. Unit 1 was returned to service in November 2005, providing 542 MW of generating capacity for Ontario's electricity system.

In August 2005, the OPG Board of Directors announced that Units 2 and 3 would not be refurbished due to specific technical and cost risks surrounding the material condition of these two units.

The Pickering Nuclear Generating Station, viewed from the west. All eight reactors are visible, from 2.5km to 3.25km away.

Waste

The used nuclear fuel and some refurbishment waste generated by the plant sits on-site at the Pickering Waste Management Facility. All operational low and intermediate-level waste is transported to OPG's Western Waste Management Facility at the Bruce nuclear site near Kincardine, Ontario. OPG has proposed the construction and operation of a deep geologic repository for the long-term storage of low and intermediate level waste on lands adjacent to the Western Waste Management Facility.[5] The Nuclear Waste Management Organization is currently seeking a site for a potential repository for the used fuel from all Canadian nuclear reactors.

Future

Ontario Power Generation (OPG) announced a two-part investment strategy for its nuclear generating stations in Durham Region. The strategy includes the decision to spend $300-million to keep some of the Pickering B nuclear reactors operating until 2020 before it begins the longer term decommissioning process as refurbishment for Pickering B station will not be pursued. The first step in the long term decommissioning process is to layup the reactors and place them into safe storage. Pickering staff will have future employment opportunities placing the Pickering units in a safe storage state, at the Darlington refurbishment and operations, or at the potential new build at Darlington.

OPG will proceed with a detailed planning phase for the mid-life refurbishment of the Darlington Nuclear Generating Station east of Toronto, with construction expected to start in 2016. The business decision to move forward with an investment in Darlington came after initial studies on the plant’s condition operating performance returned positive results. The next phase of the process will include an Environmental Assessment, an Integrated Safety Review and an Integrated Improvement Plan that will define the scope, cost and schedule of the refurbishment project.[6]

Incidents

A serious incident occurred on 1 August 1983. Pressure tube G16 in the Pickering A Unit 2 reactor developed a 2 metre long split. The reactor was safely shut down and the damage investigated. The cause was found to be the mislocation of annulus gas spacer springs which allowed the pressure tube to sag inside the calandria tube leading to hydrogen enrichment of the cooler areas. This made the tube more brittle so that it ruptured. There was some local fuel damage and the reactor was safely shut down by the operators with no increase in radioactive emissions. The eventual resolution was large Scale Fuel Channel Replacement and all the pressure tubes were replaced in all Pickering A reactors. Since then, additional monitoring of the location of the annulus gas spacer rings has been a significant part of routine reactor inspections.[7]

On December 10, 1994 there was a loss of coolant accident. Said to be the most serious accident in Canadian history (June 2001) by The Standing Senate Committee on Energy, the Environment and Natural Resources. The Emergency Core Cooling System was used to prevent a meltdown.[8][9]

In 1994 Pickering Unit 7 set a world record for continuous operation (894 days) without a shutdown. [10] [11]

On March 14, 2011, there was a leak of 73 cubic metres of demineralized water into Lake Ontario from a failed pump seal. There was negligible risk to the public according to the Canadian Nuclear Safety Commission.[12]

Pickering normally has lower operating loads than newer CANDU NPPs: Bruce and Darlington. Pickering reactors sometimes only achieve 45-70% operating loads, in comparison to 93-95% sometimes achieved at the more modern reactors. It is not unusual for earlier builds of reactor designs to perform worse than subsequent builds.

See also

References

External links

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