-加拿大5家核电厂地址与供电能力
-加拿大核电厂应急计划
-常见问题解答：核反应堆
-加拿大的核电厂
Canada five nuclear power plants Location
Bruce Nuclear Generating Stations A and B
Near: Tiverton, Ont.
Startup date: 1977
2010 generating capacity: 3,180 MW
2020 generating capacity: 3,180 MW
Ownership: Private
Owner: Cameco Corp., TransCanada Pipelines, BPC Generation
Pickering Nuclear Generating Stations A and B
Near: Pickering, Ont.
Startup date: 1971
Expected decommissioning date: 2017
2010 generating capacity: 2,064 MW
2020 generating capacity: 0 MW
Ownership: Public
Owner: Ontario Power Generation
Darlington Nuclear Generating Station
Near: Clarington, Ont.
Startup date: 1990
2010 generating capacity: 3,512 MW
2020 generating capacity: 5,512 MW
Ownership: Public
Owner: Ontario Power Generation
Gentilly-2 Nuclear Generating Station
Near: Trois-Rivières, Que.
Startup date: 1983
2010 generating capacity: 635 MW
2020 generating capacity: 635 MW
Ownership: Public
Owner: Hydro Quebec
Canada five nuclear power plants Location
Point Lepreau Nuclear Generating Station
Near: Saint John, N.B.
Startup date: 1983
2010 generating capacity: 635 MW
2020 generating capacity: 635 MW
Ownership: Public
Owner: NB Power
(An aerial view of the Pickering, Ont., nuclear plant, which has two generating stations with four reactors each, two which are currently out of operation. )
Nuclear emergency planning at Canada’s power plants
CBC News Posted: Mar 14, 2011 4:12 PM ET Last Updated: Mar 15, 2011 5:47 PM ET
Canada has five nuclear power plants in different states of operation.
Canada’s seven nuclear generating stations are located at five sites in Ontario, Quebec and New Brunswick, which have relatively low levels of seismic activity but have experienced damage-causing earthquakes in the past.
According to Natural Resources Canada, Eastern Canada, which includes those provinces, averages three earthquakes a decade of magnitude greater than 5, the threshold considered damage-causing.
The Canadian Nuclear Safety Commission (CNSC) says all of the country’s nuclear power plants have been “designed and built or refurbished to meet seismic standards.”
The plants use the Candu type of reactor, a Canadian-built pressurized heavy-water power reactor. As a condition for licensing, the reactors have to be built to withstand the strongest earthquakes recorded for the site where they will be used.
“Withstand” does not necessarily mean “not suffer any damage.” The CNSC says each Candu reactor has multiple safety systems in place to ensure that the surrounding area is not adversely affected should there be an earthquake. In an emergency, Candu reactors are supposed to automatically shut down and cool the core without a release of radiation.
2 accidents at Pickering plant
The most serious nuclear accidents in Canada occurred at the Pickering nuclear facility east of Toronto, which has two generating stations with four reactors each, in 1974 and in 1983. In each case, pressure tubes — which hold fuel rods — ruptured. The CANDU design uses much smaller pressure vessels than other types of nuclear reactors, so when a pressure tube fails, it can be replaced without taking the entire reactor off-line.
In the Pickering accidents, some coolant escaped but was recovered before it left the plant. and there was no release of radioactive material from the containment building. The plant staff were able to shut down the reactor without having to rely on the automatic shutdown systems that would kick in during a nuclear accident.
Emergency preparedness and response is a shared responsibility between all levels of government and the operator of a given plant, which all regularly participate in nuclear emergency exercises in which they practice responding to a given scenario.
Municipal governments are generally the ones overseeing emergency operations while provincial authorities are responsible for public health, safety and environmental aspects.
Ontario’s emergency plan
The highest concentration of nuclear power plants in the country is east of Toronto — the Pickering and Darlington nuclear power plants. They are located in Durham Region, and it is the Durham Emergency Management Office that is responsible for carrying out the area’s emergency response plan.
Part of that plan includes:
Alerting the public. A system of sirens is in place to warn people within a three-kilometre radius of the Darlington and Pickering power plants should there be an emergency. When the sirens go off, residents are supposed to go indoors and tune in to local radio or television stations, which will be relaying emergency information.
Automated telephone-dialing system. Everyone who lives within a 10-kilometre radius of the power plants in Durham Region will receive an automated call advising them of an emergency.
Potassium iodide pills. People who live within three kilometres of the plants will have access to free potassium iodide pills. The tablets prevent or reduce the absorption of radioiodine, a byproduct of nuclear fission, through the thyroid gland.
Evacuation. In a worst-case scenario, residents will be advised to leave the area and go to designated facilities, following evacuation routes established by the province.
Emergency Management Ontario also recommends people develop their own emergency plans.
Not all of Canada’s nuclear plants are fully operational. New Brunswick’s Point Lepreau nuclear generating station, which is near a fault line but not one that is likely to cause a major earthquake, is currently undergoing refurbishment, and the Pickering facility has only six of its eight reactors online.
Aside from nuclear power plants, Canada also has several research reactors across the country operated by Atomic Energy Laboratories Canada or universities, some of which are used for various medical and industrial purposes. Those, too, are overseen by the nuclear safety commission when it comes to adhering to seismic safety standards.
http://www.cbc.ca/news/canada/story/2011/03/14/f-nuclear-power-plants-canada-emergency-preparedness.html
Canada geese stand near the Pickering, Ont., nuclear power plant east of Toronto, which has six Candu reactors in operation. The Canadian-built reactors use heavy water to facilitate the chain reaction necessary for generating nuclear power. (Andy Clark/Reuters)
FAQ: Nuclear reactors
CBC News Posted: Mar 14, 2011 6:40 PM ET
Amidst the destruction caused by the recent earthquake and tsunami in northern Japan, particular attention is being paid to the Fukushima nuclear power plant. Several explosions at the plant and the failure of the systems used to cool its reactors have increased the risk of a meltdown.
In the wake of the Japanese disaster, the Canadian Nuclear Safety Commission (CNSC) has made numerous assurances regarding the safety of plants in this country. It stressed that none of Canada’s nuclear facilities are located on or near fault lines capable of causing a major earthquake.
CNSC has said that if an earthquake or a similar disaster were to occur here, Canadian nuclear plants would be safe because the pressurized heavy-water Candu reactors they use are particularly effective at cooling the reactor core.
Below are some basic facts about Candu reactors.
What does a nuclear reactor do?
Nuclear energy is produced through the splitting, or fission, of the uranium 235 (U-235) isotope. When a neutron hits a U-235 atom, it creates an unstable uranium isotope that divides and releases two other neutrons, as well as heat and various radioactive particles. The newly released neutrons then go on to bombard other U-235 atoms, setting off a chain reaction that continues until the uranium fuel is used up.
If the neutrons are moving too fast, they will pass through the U-235 atoms without affecting them so they must be slowed down with the help of a so-called moderator, such as water.
A reactor needs: uranium, a moderator to slow down fast-moving neutrons, a coolant to absorb the heat released during the reaction and a system for shielding radiation.
What sets apart a Candu reactor?
Only 0.7 per cent of naturally occurring uranium consists of the U-235 isotope — not enough to sustain a chain reaction. Reactors, then, either need to enrich the uranium to increase the proportion of the isotope or use a more effective moderator. Most reactors use enriched uranium although this process is more expensive.
Candu reactors use heavy water (deuterium oxide) to greatly improve the likelihood of a chain reaction. The hydrogen atom, as present in ordinary water, is almost exactly the same size as the fast-moving neutrons created by nuclear fission. When a neutron collides with hydrogen, it will lose almost all of its energy and slow down enough to facilitate the fission reaction.
However, a regular hydrogen atom can also absorb the neutron, decreasing the likelihood of fission, which is why Candu reactors use the hydrogen isotope deuterium, also known as heavy hydrogen. Deuterium will not absorb the neutron, improving the chances of a chain reaction.
Heavy water is more expensive than ordinary water, but it can support the use of natural uranium as an energy source.
Candu reactors have also been sold to nuclear plants in Romania, China and South Korea.
How does a Candu reactor work?
The reactor is best thought of as a giant tank filled with heavy water and a series of half-metre-long fuel rods bundled into what are called fuel assemblies. The fuel rods are filled with pellets of uranium in the form of uranium dioxide.
The heat generated by the fission process is transferred to the heavy water and used to produce steam that powers a turbine connected to an electrical generator that feeds the energy grid.
In order to further control the fission process, solid cadmium rods that absorb unwanted neutrons are inserted into the reactor tank, perpendicular to the fuel assemblies. There are more of these control rods than necessary as a safety precaution.
The Candu reactor is surrounded by a thick wall designed to absorb dangerous radiation generated during the fission reaction. It consists of several nested layers made up of materials such as boron and cadmium, which act like neutron shields, as well as lead and concrete, which block gamma radiation.
How many reactors are in Fukushima?
There are six reactors at the Fukushima Dai-ichi power plant, all of which are boiled-water reactors. This means ordinary water is used to cool down the fuel rods, which contain enriched uranium. At the time of the earthquake on March 11, three reactors were operational.
What is a meltdown?
Nuclear fission creates immense amounts of heat and radiation. Under normal circumstances, the reactor core is cooled by a moderator or coolant, usually water or heavy water (Candu only). To avoid catastrophe, nuclear plants always have at least one secondary source of coolant. A meltdown occurs when the nuclear fuel overheats and essentially melts, leaking radioactive material.
To protect the surrounding environment in the event of a meltdown, all reactors have a series of walls surrounding the core. Significant damage to these walls, however, could allow amounts of radioactivity to leak out.
What is the threat of meltdown at Fukushima?
When the 8.9-magnitude earthquake hit off the eastern coast of Japan, all three operational reactors immediately shut down and activated their emergency generators in order to remove residual heat. One hour later, tsunami-triggered flood waters damaged and deactivated the generators, causing heat from the reactor cores to evaporate the coolant.
At one of the reactors, efforts to use sea water and boric acid to keep fuel rods covered failed, leaving the rods exposed and increasing the risk of a meltdown.
Radioactive material has been detected in the air and water surrounding the plant, and the Japanese government has issued evacuation orders for those living within 20 kilometres of the plant. They have also distributed potassium-iodide tablets, which reduce or prevent the absorption of radioiodine, a byproduct of nuclear fission.
Currently, the incident is rated 4 on the international nuclear event scale, meaning an accident with local consequences, although that is likely to rise.
What happened at Chornobyl?
A major accident is denoted with a ranking of 7 on the international nuclear event scale ( INES — see sidebar). The only incident to warrant this ranking was the 1986 disaster at the Chornobyl nuclear plant in Ukraine, which was assigned a ranking retroactively when the INES system was created.
An accidental power surge in a reactor at the facility caused a severe meltdown. Chornobyl’s reactors were of a type known as RBMK (a Russian acronym) and used graphite as the reaction moderator.
The power surge, which occurred during a systems test, caused a series of explosions that damaged the reactor facility, leading to a leak of the graphite moderator. The graphite then ignited, resulting in a massive fire and a subsequent plume of radioactive fallout, 60 per cent of which landed in nearby Belarus. The meltdown was directly responsible for killing 31 people while the fallout led the then Soviet government to relocate nearly 350,000 people and caused incidents of radiation-related illnesses in areas as far away as Berlin and Turkey.
International nuclear event scale
Developed in 1990 by the International Atomic Energy Agency, the INES is used to communicate the severity of a nuclear event to the public. Each mark in the scale indicates a severity 10 times greater than the one below it. Events ranked 1-3 are classified as “incidents” and those ranked 4-7 as “accidents.”
1.Anomaly
2.Incident
3.Serious incident
4.Accident with local consequences
5.Accident with wider consequences
6.Serious accident
7.Major accident
http://www.cbc.ca/news/world/story/2011/03/14/f-nuclear-reactor-faq.html
Nuclear Power in Canada
Nuclear Power in Ontario
Based on the confidence gained by the successes of the Douglas Point reactor, Ontario Power Generation (OPG), then known as Ontario Hydro, committed to the construction of four reactors at Pickering, about 32 km east of Toronto on the shore of Lake Ontario. These reactors, at what is known as Station A, came online between 1971 and 1973 with capacities of 540 MW each. From 1983 to 1985, OPG brought four more similar reactors online at the Pickering site in Station B; adjacent to Station A. The electricity generated by these eight reactors when all were in operation (Pickering A unit 2 and 3 are being placed in safe storage in 2008) is about double the electricity generation of the Sir Adam Beck Hydroelectric Generating Station (2,338 MW) at Niagara Falls.
Bruce Power Nuclear Generating Station
With Ontario’s burgeoning appetite for electrical power during the industrial growth of the 1970s and 1980s, the need arose for additional nuclear power reactors to be constructed. From 1977 to 1979, Ontario Power Generation brought four 905 MW reactors online in Station A at the Bruce Nuclear Power Development site on Lake Huron about 250 km northwest of Toronto. From 1984 to 1987, four more 915 MW reactors came into operation at Bruce Station B bringing the combined capability of the facility to over 7,000 MW of electricity. The Bruce site, is the largest nuclear power station in North America and the second largest in the world next to Japan.
Today the Bruce Station is operated by a private sector company called Bruce Power which is undertaking a major refurbishment of Bruce A reactors 1 and 2 which are due online in 2011.
Pickering Nuclear Generating Station
Started during the high-demand era in 1977, four more 935 MW reactors were constructed at Darlington, about 70 km east of Toronto on the shores of Lake Ontario and came online from 1990 to 1993. The construction of Darlington was plagued with delays and numerous starts and stops to the project schedule due to a number of factors including political interference by three separate Ontario governments. Once online, the Darlington facility contributed an additional 3,740 MW of electric power to Ontario’s total electricity generation. In 2009, nuclear power generated 55.2% of Ontario’s power.
Pickering Nuclear Generating Station
In 2008, the Government of Ontario announced its approval of the construction of two new nuclear reactors at the Darlington site. On June 29, 2009 the Government of Ontario suspended the request for proposals process, but the federal approvals process for the reactor project is continuing. Darlington is expected to get two new reactors due online in 2018.
Darlington
Nuclear Power in Quebec
In 1971, the 250 MW Gentilly-1, a prototype reactor, came into operation near Trois-Rivières on the south shore of the St. Lawrence River. Built and owned by AECL and operated by Hydro-Québec staff, the reactor had design and operational problems and was not economical. It was taken out of service in 1979. Quebec has only one nuclear power station in operation: Gentilly-2, owned by Hydro-Québec. Equipped with a 675 MW CANDU 6 reactor, the plant was constructed on the same site a Gentilly-1 and came into commercial operation in 1983.
Gentilly-2
Nuclear Power in New Brunswick
New Brunswick was Canada’s third province to produce electricity using nuclear energy. In 1983 a 680 MW CANDU 6 reactor came online at Point Lepreau on the Bay of Fundy. With a considerably smaller population base than Ontario or Quebec, the single reactor facility at Point Lepreau is capable of producing nearly one third of New Brunswick’s electrical power. In March 2008, the process of refurbishing the Point Lepreau reactor began. It is due back online in 2011.
As a whole, CANDU have been among the top performing reactors in the world. Their ability to fuel online enables them to reduce the amount of down time of the reactor, compared to light water reactors (LWR). The older generation reactors typically run at 80% of capacity, whereas the older LWRs were typically down for maintenance or fuelling nearly half the time. The newer generation CANDU reactors project a capacity factor of 90%, however, improved LWRs have a similar capacity factor.
Point Lepreau
The 1970s and 1980s were prolific times for the Canadian nuclear industry. A total of 23 reactors were constructed with a total capacity of over 15,000 MW of electrical power – approximately 20% of Canada’s demand at that time. Interestingly, the 1990s saw a dramatic decrease in the growth of electricity demand, resulting in a veritable halt in the construction of any additional Canadian nuclear generating facilities. The arrival of the new millennium however, has brought with it a renewed enthusiasm, a renaissance for nuclear energy as an economically viable and environmentally sound piece of the puzzle to solving the world’s current energy dilemmas. With rising oil costs, growing concerns for the negative effects of greenhouse gas emissions on worldwide climate change, and a predicted doubling in world electricity consumption by 2030, nuclear power is again factoring into the planet’s energy equation. At this time (2010) there are 54 new nuclear power plants under construction and almost 500 planned or proposed throughout the world. It appears we may have only begun to see the role that nuclear power generation, and Canada’s contributions in particular, may play in supplying the world with the power needed to sustain its growth and ensure its well-being.
http://www.cna.ca/curriculum/cna_can_nuc_hist/nuclear_canada-eng.asp?bc=Nuclear%20Power%20in%20Canada&pid=Nuclear%20Power%20in%20Canada
