Beznau Nuclear Power Plant - AbsoluteAstronomy.com

The Beznau Nuclear Power Plant (in German Kernkraftwerk Beznau, abbreviated KKB) is located in the municipality Döttingen

Döttingen, Switzerland

Döttingen is a municipality in the district of Zurzach in the canton of Aargau in Switzerland.-History:Some items from the Neolithic period and two Roman era estates have been discovered in Döttingen. The modern municipality of Döttingen is first mentioned in 1239 as Totingen...

(Canton of Aargau, Switzerland) on an artificial island in the Aar river. It is operated by Axpo AG.

Beznau 1 and 2

Beznau 1 is the first commercial nuclear power reactor in Switzerland.

Putting an end to the traditional predilection of the Swiss power utilities for hydroelectric power, in the beginning of the 1960s the then Nordostschweizerische Kraftwerke AG (NOK, now part of Axpo AG) started to take into account the construction of a nuclear power plant. On the Swiss Federal Office of Energy recognized the artificial island in Beznau as potential location for a reactor. The corresponding construction permit was issued on and, after only four years, on commissioning was authorized. On Beznau 1 started commercial operation.

In the meantime the procedure for the construction of the identical reactor Beznau 2 had begun. The location and a first construction permit were approved on , followed on by the final one. The commissioning started on and the reactor finally entered the commercial operation phase on .

Beznau 1 obtained an unlimited operating license already on . On the contrary Beznau 2 received temporary licenses until , when the Swiss Federal Council

Swiss Federal Council

The Federal Council is the seven-member executive council which constitutes the federal government of Switzerland and serves as the Swiss collective head of state....

removed the limitation.

The power plant was built in the 1960s, when little opposition to nuclear projects was present. Over the years Beznau has been the scene of some anti-nuclear

Anti-nuclear

The anti-nuclear movement is a social movement that opposes the use of nuclear technologies. Many direct action groups, environmental groups, and professional organisations have identified themselves with the movement at the local, national, and international level...

protests, but such opposition never widespread among the majority of the local population. The cantonal citizens systematically rejected all votes on early shutdown of existing plants and on building suspension of new ones. Finally, in 2007 the cantonal parliament entrusted the government to act in order to promote the building of a new reactor.

As of 2008 no date for a definitive shutdown of the KKB has been set. This should nevertheless lie in the 2020s, when the two reactors will become 50–60 years old.

Beznau replacement nuclear power plant

In view of the substitution of the plant, the Resun AG

Resun AG

Resun AG is a company located in Aarau . Its purpose is to manage the construction of two new nuclear reactors...

submitted to the federal authorities on a framework permit application for a third reactor, also known as EKKB (Ersatzkernkraftwerk Beznau) or Beznau 3. Although the technical specifications will be defined in a second time, the reactor of choice should be of 3rd generation

Generation III reactor

A generation III reactor is a development of any of the generation II nuclear reactor designs incorporating evolutionary improvements in design developed during the lifetime of the generation II reactor designs...

light water type with an electrical power of 1450 MW. The cooling should be ensured by an hybrid tower

Cooling tower

Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or in the case of closed circuit dry cooling towers rely...

Reactors and generators

The KKB is composed of two identical pressurized water reactors units (Beznau 1 and 2) delivered by Westinghouse Electric

Westinghouse Electric Company

Westinghouse Electric Company LLC is a nuclear power company, offering a wide range of nuclear products and services to utilities throughout the world, including nuclear fuel, service and maintenance, instrumentation and control and advanced nuclear plant designs...

.

Both reactors are certified for the use of MOX fuel

MOX fuel

Mixed oxide fuel, commonly referred to as MOX fuel, is nuclear fuel that contains more than one oxide of fissile material. MOX fuel contains plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium fuel used in the...

. As for October 2008 (39th operational cycle) Beznau 1 hosted 12 bars out of 121 contain MOX, while for Beznau 2 this ratio increased to 32 of 121 (37th cycle).

Characterized by a thermal power of 1130 MW, each unit produces 365 MW net electricity through two Brown Boveri

Brown, Boveri & Cie

Brown, Boveri & Cie was a Swiss group of electrical engineering companies.It was founded in Baden, Switzerland, in 1891 by Charles Eugene Lancelot Brown and Walter Boveri who worked at the Maschinenfabrik Oerlikon. In 1970 BBC took over the Maschinenfabrik Oerlikon...

steam generators. Over the years the net electric power produced has been increased twice: it was 350 MW until and 357 MW until . The energy is delivered to the 220 kV grid.

The plant is cooled using the water of the Aar river and through the district heating

District heating

District heating is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating...

system REFUNA, that provides eleven surrounding municipalities with 150 GW·h/y.

Unit	Type	Net electrical power	Gross electrical power	Construction start	Critical state	Connected to electricity grid	Commercial operation	Shutdown
Beznau 1	PWR Pressurized water reactor Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...	365 MW	380 MW	Sep. 1965	Jun. 1969	Jul. 1969	Dec. 1969	–
Beznau 2	PWR Pressurized water reactor Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...	365 MW	380 MW	Jan. 1968	Oct. 1971	Oct. 1971	Mar. 1972	–

Safety measures

Since the commissioning of the two reactors numerous upgrades have been carried out to improve safety. In the 1990s the steam generators and the control technology of the reactor protecting system have been replaced. The control rooms were consequently adapted and new turbine controls installed. Furthermore each reactor block has been equipped with an emergency building (NANO, NAchrüstung NOtstandsystem). These contain additional safety systems for the reactor emergency shutdown and for the feeding of the steam generators, a 50 kV emergency power line, and a diesel generator. They are heavily protected from external hazards and, if needed, are able to cool and shut down the power plant without human intervention.

The at least 1.5 m thick concrete-steel housings protect the critical systems from external agents like earthquakes or plane crashes. Each unit of the KKB has a large dry type containment in steel.

The core emergency cooling is performed by a redundant high-pressure safety injection system with a total of three strands (one in the NANO). The two steam generators are provided with water by two main feeding pumps. If they fail, feeding is taken over by one of the security systems: a double-stranded auxiliary feedwater system with 200% after-heat removal capacity or one of the two emergency feedwater systems, one if which is part of the NANO. Finally, in case of problems with the cooling, two containment spray systems are entrusted with the removal of excessive heat and pressure by condensation of the resulting steam.

The power plant is connected thorough five strands to the external power grid. Two of them are mainly used to deliver the power plant output to the 220 kV grid. They are nevertheless equipped with an emergency diesel generator each. Two other strands provide emergency power and are connected to the nearby hydroelectric power plant and the 50 kV grid. Further two diesel generators expressly equipped to be able to work in case of flood are also available. The NANO is connected through the fifth strand to the 50 kV grid and contains a fifth generator. The plant main UPS

Uninterruptible power supply

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails...

system can provide electricity for at least 2 h of normal operation.

Waste Management

The KKB possesses since 1993 a separate interim radioactive waste storage facility (ZWIBEZ). It is composed by an hall for low level operational waste and a second one for the dry storage of spent fuel. The waste needing conditioning is stored in the central interim storage facility (ZZL). These two deposits should ensure the storage of the plant's waste until at least 2020.

Nuclear events

Year	INES level								Total
Year	0	1	2	3	4	5	6	7	Total
2009	10	0	1	0	0	0	0	0	11
2008	4	0	0	0	0	0	0	0	4
2007	7	1	0	0	0	0	0	0	8
2006	2	0	0	0	0	0	0	0	2
2005	2	0	0	0	0	0	0	0	2
2004	2	0	0	0	0	0	0	0	2
2003	4	0	0	0	0	0	0	0	4
2002	2	0	0	0	0	0	0	0	2
2001	5	0	0	0	0	0	0	0	5
2000	4	0	0	0	0	0	0	0	4
1999	5	0	0	0	0	0	0	0	5
1998	2	0	0	0	0	0	0	0	2
1997	6	1	0	0	0	0	0	0	7
1996	3	1	0	0	0	0	0	0	4
1995	3	0	0	0	0	0	0	0	3
Total	61	3	1	0	0	0	0	0	65

2009

On , during the yearly revision of Beznau 2, two workers were exposed to too high levels of radiation because of a series of organizational errors and a wrong manipulation by another revision team. These lead to a sudden increase of the radiation level in the room where the two technicians were working. They absorbed a dose of 37.8 and 25.4 mSv, respectively. Incorrect settings of the personal dosimeters prevented a timely warning.

2007

In August, during the yearly revision of Beznau 2, the 50 kV emergency power line was deactivated. Consequently the diesel generator of Beznau 1 was switched on at low regime as prescribed by the security regulations. After the reconnection of the 50 kV line, the generator run at higher load because of technical reasons, but it eventually failed due to a defective relay. It was therefore to assume that while the 50 kV line was not active the generator would not have been able to run at full loading. Since also the unit 2 generator was not available due to the planned revision, the emergency power could be provided only by the hydroelectric plant or some reserve generators that are activated in case of flood. The decrease in redundancy comported a deviation from the normal operation parameters and was therefore classified as a level 1 event (Swiss scale level B).

1997

In the course of a periodic inspection carried out by the operating personnel, a manually operated valve, which should have been open, was found to be closed. As result of the false position, one of three emergency cooling systems of Beznau 1 was not ready for immediate use over a period of two weeks. This breach of the technical specifications led to the incident being assessed as level 1 (Swiss scale level B).

1996

After the revision outage, at 1 to 2% of reactor power, the new protection system for Beznau 1 and its internal power supply was to be started up with a test program. During synchronization with the new protection equipment, one of the two turbo groups inadvertently increased the load, and this caused a rise in reactor power to 12.6%. Since only the auxiliary feedwater pumps are in operation during low power, the amount of water supplied was insufficient to feed the steam generator, leading to an automatic reactor scram. The inadvertent demand on the turbo group was caused by an unforeseen reaction of the automatic turbine controller. Besides, the reactor already went critical at 251 °C instead of at the prescribed minimum temperature of 276 °C. The deviation from the operation specifications led to a level 1 assessment (Swiss scale level B).

Significant events before 1995

In July 1992, during a revision of Beznau 1, two technicians working in the reactor sump
Sump
A sump is a low space that collects any often-undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers....

died by suffocation. This was caused by an excessive atmospheric concentration of the argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

used for welding. This tragic accident was not due to the nuclear nature of the plant and therefore didn't receive an INES assessment.

External links

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