Beznau nuclear power plant

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Beznau nuclear power plant
Beznau nuclear power plant
Beznau nuclear power plant
Beznau nuclear power plant (Canton of Aargau)
Beznau nuclear power plant
Coordinates 659 402  /  267 132 coordinates: 47 ° 33 '8 "  N , 8 ° 13' 40"  O ; CH1903:  six hundred and fifty-nine thousand four hundred and two  /  two hundred sixty-seven thousand one hundred and thirty-two
Country: Switzerland
Owner: Axpo AG
Operator: Axpo AG
Project start: 1965
Commercial operation: Sept. 1, 1969

Active reactors (gross):

2 (760 MW)
Energy fed in in 2009: 5,825,801 GWh
Energy fed in since commissioning: 207,860.875 GWh
Was standing: December 31, 2009
The data source of the respective entries can be found in the documentation .

The Beznau nuclear power plant , or KKB for short , is located in the municipality of Döttingen ( Canton Aargau , Switzerland ) on the artificial Aare island of Beznau .

The KKB consists of two identical blocks (Beznau 1 and 2) with pressurized water reactors from Westinghouse , each with an electrical output of 365  MW . It is cooled with water from the Aare. The nuclear power plant generates around 5 billion kWh of electricity per year and supplies - with part of the waste heat - via the Refuna (Regional Fernwärme Unteres Aaretal) eight surrounding communities with around 170 million kWh of district heating per year. Both nuclear reactors are among the longest serving in the world.

The owner and operator of the KKB is Axpo AG (until it was renamed Nordostschweizerische Kraftwerke NOK in 2009 ).


The NOK began planning a large power plant in 1957 and in 1964 decided on the nuclear energy option . In 1969 Beznau 1 started operations after four years of construction. In 1971, the identical Beznau 2 block went online. The technical staff was in Böttstein Castle on the opposite side of the Aare. Beznau 1 was the first nuclear power plant in Switzerland. Since the shutdown of the Oldbury nuclear power plant in England on February 29, 2012, it has been considered the world's oldest operating nuclear power plant.

Both units of the nuclear power plant have an unlimited operating license. The prerequisite for the operation is the ongoing fulfillment of the legal, official and in-house safety requirements. The actual operating time depends on the ongoing review of the safety and economic efficiency of the blocks.

In October 2015 it became known that an inspection of the reactor pressure vessel of reactor block 1, which was shut down in March 2015 for maintenance work, discovered around 1000 weak points. With the help of the reproduction of an element of the pressure vessel, it was possible to show that the inclusions were created during manufacture and have no negative influence on the material properties.

Safety measures

Since the commissioning of the two systems, retrofits and renewals have been carried out to increase safety.

  • Both steam generators were exchanged in Block 1 in 1993 and in Block 2 in 1999.
  • The command rooms were adapted, a new turbine control was installed. The control technology of the reactor protection system was replaced by new electronics.
  • A separate emergency building was built for each block. It contains additional safety systems for core emergency cooling and supplying the steam generator as well as an additional 50 kV emergency power line and an additional diesel generator. The safety systems in the emergency buildings are designed to run the power plant down and shut it down without an operator. The buildings are particularly well protected against external influences, such as plane crashes, earthquakes and external influences.
  • The emergency power supply has been rebuilt in recent years: four bunkered diesel generators are to guarantee the emergency power supply and thus replace the Beznau hydraulic power station. This modernization has been in operation since December 2015.
  • The fuel element storage (also wet storage ) of Beznau I and II were initially converted from the original 163 storage spaces for fuel elements (sufficient for a core unloading in emergencies as well as an annual load) to a compact storage facility. The capacity was expanded to 340 storage locations by installing absorber material in the storage racks.


Reportable Incidents

The following table summarizes the nuclear disruptions according to the INES international event scale . Level 0 is classified as a deviation, levels 1 to 3 are classified as incidents and incidents, and levels 4 to 7 as accidents. Since the power plant was commissioned, there has been one level 2 event and four level 1 events.

year International event scale INES total
0 1 2 3 4th 5 6th 7th
2014 5 - - - - - - - 5
2013 7th - - - - - - - 7th
2012 13 1 - - - - - - 14th
2009 10 - 1 - - - - - 11
2008 4th - - - - - - - 4th
2007 7th 1 - - - - - - 8th
2006 2 - - - - - - - 2
2005 2 - - - - - - - 2
2004 2 - - - - - - - 2
2003 4th - - - - - - - 4th
2002 2 - - - - - - - 2
2001 5 - - - - - - - 5
2000 4th - - - - - - - 4th
1999 5 - - - - - - - 5
1998 2 - - - - - - - 2
1997 6th 1 - - - - - - 7th
1996 3 1 - - - - - - 4th
1995 3 - - - - - - - 3
total 86 4th 1 - - - - - 91
Sources : 2014 2013 2012

Level 2

During the annual inspection in Block 2, two employees were exposed to an increased dose of radiation. The values ​​measured by employees were 37.8 and 25.4 millisieverts, respectively, above the permitted radiation dose of 20 millisieverts. There was no health risk.

step 1

On August 21, 2007, during the annual overhaul of Unit 2, an incident occurred. The common reserve grid feed was switched off for maintenance work. To compensate, the emergency diesel generator of Block 1, which is running at full load, was switched on while idling. After the reserve network was re-established, it was noticed that this diesel generator would not have fulfilled its emergency power function due to a malfunction. According to the HSK, there would theoretically have been a cross connection to the emergency diesel of the shutdown unit 2, but this generator was also in maintenance.

On May 10, 2012, during a test run, an emergency diesel generator malfunctioned in Unit 2. Due to this incident, the nuclear regulatory authority only gave reactor Unit 2 the grade 'sufficient' in the 2012 supervisory report.

Other events

The reactor emergency shutdown button of a reactor

On January 31, 2008 at six o'clock in the morning, there was an unforeseen emergency shutdown in reactor block 2. The power supply to several display instruments in the main control room of the NPP had previously failed. As a result, the signals required to regulate the reactor power were also lost. This in turn led to an automatic reduction in reactor output. The responsible staff therefore also reduced the turbine output. Because it lacked the necessary display information, it could not prevent an automatic blow-off of live steam from being triggered. At 6:19 a.m., the operating personnel finally triggered a quick shutdown of the reactor manually for safety reasons and the plant was stabilized. The defective part of the system was located and replaced.

On the evening of April 10, 2008, a turbine generator group in Block 2 of the Beznau nuclear power plant was switched off after around 50 liters of oil had leaked in the non-nuclear section. After the turbine generator group was shut down, the reactor output was reduced by half. The oil leak was due to a leak at the junction of an oil line. The repair with the group switched off took around twelve hours. The turbine generator group was put back into operation on April 12, 2008 at 11:30 p.m.

On January 9, 2009, increased radioactivity was measured at the exhaust chimney, after which parts of the containment were sealed to hold back radioactivity. According to the operator's statement, no radiation was exposed, only a measuring device was defective.

On May 1, 2009, radiation leaked from the nuclear power plant due to a leak in a monitoring system valve. Samples of radioactive exhaust gases were released into the environment via the exhaust chimney instead of being fed back into the system. According to the operator, the radiation was just above the detection limit, but clearly below the permissible emission limit.

On March 23, 2012, there was a leak in a pump in the primary circuit of Unit 2, which was then switched off.

On June 18, 2012, it became known that damage to a weld seam inside the reactor lid had been discovered. The operator then instructed a repair.

On November 21, 2012 there was an emergency shutdown of Unit 2 due to a defective steam generator in the non-nuclear circuit.

On June 16, 2014, a crack in a weld seam was discovered in reactor block 1, through which cooling water could escape.

In July 2015, irregularities in the material of the reactor pressure vessel were found in Unit 1. In October 2015 it became known that when the reactor pressure vessel of this block was checked with new, previously unavailable measurement technology, around 1000 displays were discovered. These are inclusions up to half a centimeter in length, these are enclosed within the up to 17 centimeters thick steel walls of the reactor vessel. Each individual display was measured and evaluated in three dimensions, and the results were submitted to ENSIand the international experts called in. The formation of such inclusions is inevitable with forgings of this size, their existence is covered with the usual safety margins (without the additional factors for nuclear plants). Complete cataloging should also be able to provide proof in the future that the displays are production-related and do not change due to the operation of the reactor. Similar circumstances in Belgium also led to long downtimes in the Doel 3 and Tihange 2 reactors , but these were allowed to operate again. In the event of a political decision by the Federal CouncilAxpo threatened to take both reactors off the grid with a claim for damages of up to two billion Swiss francs.

On March 6, 2018, ENSI announced that Axpo had provided the necessary evidence for the safety of the reactor cask in Unit 1. The international expert commission set up with globally recognized experts had also come to the same conclusion. Axpo was thus granted permission to operate the reactor again after three years of downtime. Block 1 resumed operations on March 20, 2018.

Non-nuclear events

On July 17, 1992, two workers from external companies who were doing revision work in Beznau died in Beznau. The two workers went into the "reactor sump", a collecting basin under the reactor, which would have to collect leaking radioactive water in an emergency. However, the odorless noble gas argon had accumulated there. The gas is heavier than air and displaces the air we breathe, which is why the workers suffocated. Other workers reported that the pump that should have pumped the gas from the reactor sump was removed and used elsewhere. The two accident victims could not have known this. The HSK (Main Department for the Safety of Nuclear Installations) classified the fatal accident as a "non-nuclear" accident that does not fall within their area of ​​responsibility.

On August 9, 2007, heavy rain and floods prevented the power plant from being supplied with emergency power by the Beznau hydropower plant for around twelve hours (NOK press release). Several additional emergency power lines are available in the power plant. In the event of a breakdown of the external power supply, bunkered, flood-proof diesel generators are available. Nevertheless, according to safety regulations, the Beznau nuclear power plant must be shut down after a maximum of 24 hours if the emergency power line of the hydropower plant fails. In the case of the flood event mentioned, the hydropower plant was back in normal operation before this deadline.

In 2009, the nuclear regulatory authority discovered rusty areas on the reactor protective cover. The scope is unclear; a report has been announced for 2016.

On the morning of March 5, 2014, around 100 Greenpeace activists broke into the site and attached a banner reading 'The End' to the reactor building in Block 1. The aim of the campaign was to draw attention to the old age of the plant and the resulting potential danger.

In May 2015 it became known that a new cover for the reactor pressure vessel that had previously been ordered for reactor block 1, weighed 52 tons and cost 50 million francs, did not fit on the reactor, which made an adjustment necessary.

At the end of June 2015, the nuclear supervisory authority requested the operator to retrofit the facility to protect it from the risk of flooding.

Due to the high temperature of the Aare, the power plant's output had to be reduced in 2003 , 2015 , 2018 and 2019 .


In September 2010, the environmental activist Stefan Fuglister revealed that the operating group Axpo is receiving nuclear fuel for Beznau from the Mayak nuclear facility . The Soviet Union used the facility, which is still a restricted military area, to manufacture nuclear weapons . Despite repeated inquiries, Axpo never had access to the system. Due to the lack of transparency on the part of its Russian trading partner, Axpo stopped purchasing uranium from Mayak in 2011.

In August 2015, residents and environmental organizations complained that the facility was not earthquake-proof. The nuclear supervisory authority had assumed incorrect radiation protection values ​​in its calculations.

The re-commissioning of reactor unit 1 after around three years of standstill caused criticism at the end of March 2018. The Social Democratic Party of Switzerland described the start-up of the plant as "irresponsible". The party filed a supervisory complaint against the Department of Energy Minister Doris Leuthard for alleged non-compliance with the radiation limits and called on the Federal Council to withdraw the operating license for both units from the operators. "ENSI is giving the green light for a daring experiment that is endangering the health and home of hundreds of thousands of people in Switzerland and neighboring countries," criticized the Greens Aargau. The Swiss Green Partycriticized the restart as "highly irresponsible". The Environment Minister of the State of Baden-Württemberg ( Cabinet Kretschmann II ), Franz Untersteller ( Bündnis 90 / Die Grünen ), criticized the safety of the power plant and referred to an opinion by the Freiburg Eco-Institute , which shows significant deficiencies in the Beznau nuclear power plant. The deputy director of ENSI found the critical assessment to be unjustified. The Tri-national Atomic Protection Association(TRAS), in which environmental protection organizations from Switzerland, Germany and France are united, also condemned the restart. The nuclear supervisory authority (ENSI) applied outdated safety criteria and did not comply with the provisions of the current legislation.

New building in Beznau III

On December 4, 2008, a general license application was submitted for the construction of a third nuclear power plant block. At the same time, a general license application for the Mühleberg site was submitted. A structurally identical light water reactor with an output of between 1,200 and 1,600 MW el was planned as the reactor type at both locations . The cross-party and cross-association alliance Stop Atom announced an optional referendum against the planned buildings immediately after the submission was announced .

After the nuclear disaster in Fukushima in March 2011, Federal Councilor Doris Leuthard suspended all general license applications for new nuclear power plants and ordered an early safety check for all existing power plants. The focus here is on earthquake safety and reactor cooling. According to Leuthard, all Swiss nuclear power plants can withstand a magnitude 7 earthquake. Such a quake is considered to be a millennium event for Switzerland.

Data of the reactor blocks

The Beznau nuclear power plant has a total of two blocks :

Reactor block Reactor type net
start of building Network
Operating license
Beznau-1 Pressurized water reactor 365 MW 380 MW 09/01/1965 07/17/1969 09/01/1969 Unlimited
Beznau-2 Pressurized water reactor 365 MW 380 MW 01/01/1968 October 23, 1971 December 01, 1971 Unlimited

Revision of the date of commissioning

In the run-up to the nuclear phase -out initiative, ENSI revised the date for the commissioning of Beznau I. The nuclear power plant operators did not use the term commissioning "uniformly". On September 6, 1969, Beznau I went online for just one test program. A standardization of all Swiss nuclear power plants now leads to the actual commissioning of Beznau I on December 9, 1969. This means that Beznau I slipped to fifth on the list of the oldest nuclear reactors behind Tarapur 1 and 2 , Oyster Creek (closed in 2018) and Nine Mile Point 1 Rank.

See also

Web links

Commons : Beznau nuclear power plant  - collection of images, videos and audio files

Individual evidence

  1. Home. Regional district heating Lower Aare Valley (REFUNA), accessed on August 16, 2015 .
  2. a b c Aargauer Zeitung : Beznau is no longer the oldest nuclear power plant in the world - how is that suddenly possible? , October 14, 2017, accessed November 18, 2017.
  3. Oldbury nuclear power station stops electricity generation , The Independent, accessed February 29, 2012
  4., Lokales, Aargau, February 23, 2012, bz: The oldest nuclear power plant in the world will soon be running in Switzerland (February 26, 2012)
  5. DETEC media release (dated December 3, 2004)
  6. Procedure for the operating license for the Beznau NPP, Block II, list of all retrofits from page 40 . Archived from the original on September 26, 2011. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved December 20, 2008. @1@ 2Template: Webachiv / IABot /
  7. ↑ Changing the steam generator on the KKB-2 | Nuclear Forum Switzerland. Retrieved February 14, 2017 .
  8. News - .
  9. Statement of the HSK on deliberate plane crashes on nuclear power plants .
  11., nux-number 4, September 1978: The matter with the fuel elements in the basin ( Memento of January 21, 2005 in the Internet Archive ) (May 18, 2011)
  12. 2014 ENSI Oversight Report - ENSI-AN-9252. ENSI , June 24, 2015, accessed on January 19, 2020 .
  13. 2013 ENSI Oversight Report - ENSI-AN-8800. ENSI , June 30, 2014, accessed on January 19, 2020 .
  14. ENSI Supervisory Report 2012. ENSI , June 24, 2013, accessed on January 19, 2020 . }
  15. Radiation due to "insufficient coordination" - NZZ . 4th August 2009.
  18. - ( Memento of the original from March 5, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@2Vorlage:Webachiv/IABot/
  19. ENSI supervisory report 2012 . S. 37 , .
  20. HSK classified incidents in Swiss nuclear power plants , accessed on February 11, 2008
  21. Felix Maise, Tagesanzeiger record number of breakdowns in the Beznau nuclear power plant , accessed on February 11, 2008
  22. NZZ online (sda) Fault in the Beznau nuclear power plant , accessed on April 15, 2008
  23. Basler Zeitung (ap & baz) Turbine in Beznau nuclear power plant back in operation  ( page can no longer be accessed , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , accessed April 15, 2008@1@2Vorlage:Toter Link/  
  24. Fehlerhaftes-anmachen-eines-kaminaktivitaetsmonitors-stand-26-3-2009 /
  25. Beznau nuclear power plant: radiation leaked .
  27. cis: Incident in the cooling system, Swiss people have to shut down the ancient reactor , Spiegel Online, Date: March 24, 2012, Accessed: March 24, 2012
  28. ^ Reactor shutdown in the Beznau 2 nuclear power plant »ENSI . March 23, 2012.
  29. - ( Memento of the original from March 27, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@2Vorlage:Webachiv/IABot/
  30. Beznau nuclear power plant: irregularity discovered in the reactor cover .
  31. ^ Fault in Beznau nuclear power plant . November 21, 2012.
  32. ^ Reactor shutdown in the Beznau 2 nuclear power plant »ENSI . November 21, 2012.
  33. Leak in the Beznau nuclear power plant: supervisory authority calls for further analyzes .
  34. Now Beznau 2 also has to be offline . August 13, 2015.
  35. Stefan Häne, Inland editor @ stefan_haene: 1000 weak points in the heart of Beznau 1 . August 10, 2015.
  36., 20 minutes, 20 minutes, Axpo threatens the federal government with billions in lawsuits .
  37. Beznau 1: Aluminum oxide inclusions have no negative impact on the safety of the reactor pressure vessel
  38. Beznau 1 is allowed to connect again | NZZ . In: Neue Zürcher Zeitung . March 6, 2018, ISSN  0376-6829 ( [accessed March 6, 2018]).
  39. a b AKW Beznau I is back on the grid - NZZ . 20th March 2018.
  40. Susan Boos, Radiant Switzerland. Manual for the nuclear industry, Rotpunktverlag, 1999, p. 56
  41.  ( page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@2Vorlage:Toter Link/  
  42. Why does nuclear supervision need 7 years for the rust report on Beznau nuclear power plant? .
  43. ^ Activists break into Swiss nuclear plant .
  44., 20 minutes, 20 minutes, The new lid does not fit on the reactor .
  45. Beznau nuclear power plant: Reactor pressure vessel cover successfully placed - time adjustments for the revisions of Units 1 and 2. Accessed on August 17, 2020 (Swiss Standard German).
  46. Beznau nuclear power plant has to retrofit due to the risk of flooding .
  47. Temperature monitoring of rivers: fever measurements on Swiss rivers. Federal Office for the Environment , August 24, 2016, accessed on January 17, 2020 .
  48. ^ Mathias Küng: Because of the heat: Beznau nuclear power plant throttles its output to 50 percent. In: . July 25, 2019, accessed July 25, 2019 .
  49. ^ Uranium origin from Axpo: Secreter than Appenzeller cheese , Aargauer Zeitung, 8 September 2015
  50. No more uranium from Mayak | NZZ . In: Neue Zürcher Zeitung . January 27, 2014, ISSN  0376-6829 ( [accessed March 6, 2018]).
  51. Beznau nuclear power station is due to be disconnected from the network due to insufficient earthquake security . 20th August 2015.
  52. Valentin Schmidt: Federal Council wants to increase radiation risk by a factor of 100 . In: Energy & Environment: the magazine of the Swiss Energy Foundation SES . tape 2018 , no. 1 ( [accessed on February 1, 2020]).
  53. ^ Badische Zeitung: Block I of the Beznau nuclear power station back on the grid - Aargau - Badische Zeitung .
  54. Ultrasound findings from the Beznau nuclear power plant (pdf, March 2016)
  55. Nuclear power station near the German border goes back into operation
  56. ENSI contradicts the Beznau criticism of the Environment Minister of Baden-Württemberg. In: May 23, 2018, accessed January 6, 2020 .
  57. Ralf Streck ": Ailing Swiss ancient kiln Beznau back online. Accessed on March 22, 2018 .
  58. admin: - and other domains buy cheap and easy online at . 4th October 2016.
  59. Applications for new nuclear power plants open old trenches - NZZ . December 4, 2008.
  60. ^ General license applications for replacement nuclear power plants suspended , NZZ, March 14, 2011
  61. Power Reactor Information System of the IAEA : "Switzerland (Swiss Confederation): Nuclear Power Reactors" (English)