BN reactor

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BN reactor
Developer / Manufacturer: OKBM
Developing country: RussiaRussia Russia
Reactor data
Reactor type: Breeder
Design type: pool
Cooling: sodium
Power classes in MW (gross): 90, 600, 800, 1200, 1600
Containment: unavailable
Copies built: 3

The BN ( Russian БН, Реактор на Б ыстрых Н ейтронах , transcribed Reaktor na B ystrych N ejtronach , in German about reactor for fast neutrons or analogously fast breeder ) is a sodium-cooled breeder reactor of various power versions from the Russian company OKBM . Currently (as of 2019) two BN reactors are in operation worldwide.

The BN reactors are said to be able to achieve a breeding ratio of up to 1.3, i.e. to produce 30% more plutonium from uranium- 238 than they consume in the same amount of fissile material. The excess could be used in light water reactors . The natural uranium could be used up to 60 times more efficiently than in conventional reactors. However, since 2012 the BN-600 has been used as a burner reactor to burn the plutonium from Russian nuclear weapons . H. with a breeding ratio below 1.

Overview of the different types

Type power Fuel assemblies Cooling circuits Operating data
Thermal
[MW th ]		 Electric
[MW e ]		 business status
BN-350 750 135 1972-1999 Shut down
BN-600 1470 600 369 1980–0000 In operation
BN-800 2100 864 4th 2014–0000 In operation; planned service life: 60 years
BN-1200 2900 1220 4th After 2030 In planning; planned service life: 60 years

Source:

BN-350

The first BN reactor with the type designation BN-350 was commissioned in 1973 in the Aqtau nuclear power plant (then the USSR ). The reactor was in operation for 27 years and, in addition to its experimental purpose, was used to generate heat for water desalination .

BN-600

BN-600 in the Beloyarsk nuclear power plant
Model of the BN-600 reactor on display at the Beloyarsk Nuclear Power Plant
Fuel element of a BN-600

The BN-600 is the further development of the BN-350. The reactor was installed in the Belojarsk nuclear power plant and has been in commercial operation since 1980 (as of 2015). The output is 600 MW gross and 560 MW net. Unlike the BN-350, the reactor was built in a pool design and is therefore one of the more advanced breeder reactors. The Belojarsk reactor has no containment, among other things because, unlike the cooling water of a PWR or BWR , the liquid metal is not under pressure.

With 35 years of operation and an availability of over 74%, the BN-600, together with the French Phenix reactor , is one of the most successful fast breeder reactors to be connected to the grid.

A reactor based on the BN-600 with a capacity of 85 MW th (CEFR China Experimental Fast Reactor) went into operation in China in 2011.

BN-800

The BN-800 is a further development of the BN-600. It will also be built in pool construction. In Belojarsk, construction began on a BN-800 in 2006, which went into commercial operation at reduced power in June 2014. On December 7th, 2007 the first two sodium tanks were installed and filled. The tanks have a length of 15 m, a diameter of 4 m and weigh 54 t. The BN-800 is similar to its predecessor, but constructed in a larger version and according to more stringent safety standards. Criticality was reached on June 27, 2014. In December 2015 it was connected to the power grid with a minimum output of 235 MW and in August 2016 the first 15-day test phase at nominal output was successfully completed. Commercial operation started on November 1, 2016. The construction of two BN-800 reactors in China was agreed in 2009. Currently (2019) there has been no start of construction. According to press information, the contract was terminated.

BN-1200

The BN-1200 is planned as the successor to the BN-800. A decision about the construction should be made in 2019 [out of date] . However, the BN-1200 construction was postponed by 4 to 8 years in mid-2019. In addition to the higher output of 1200 MW, the BN-1200 should meet the even higher safety standards of Generation IV . Breeding ratios up to 1.45 are planned.

safety

Advantages:

  • the low pressure of the liquid metal (atmospheric pressure or slightly higher, compared to the approximately 150 bar of a pressurized water reactor and about 75 bar of a boiling water reactor ).
  • With the BN-800, the residual power can be absorbed completely passively by the decay heat when the reactor is switched off. H. without the use of pumps as with light water reactors of the 2nd and 3rd generation.
  • Iodine , the most dangerous radioactive element in nuclear accidents, can be bound by sodium to form a non-volatile compound.


Disadvantage:

  • Sodium reacts violently with air humidity or water to form caustic soda and hydrogen. The hydrogen formed can react explosively. Sodium also reacts intensively with atmospheric oxygen. Appropriate security measures must therefore be taken. In the BN-600 there were several leakages of sodium between 30 and 1000 kg, which led to fires and reactions with water. These events could be controlled.
  • The melting point of sodium is 98 ° C at normal pressure. The system must therefore be kept at constant temperature even when the reactor is at a standstill, which, however, is easily possible electrothermally. However, the reactor vessel itself is adequately heated by the decay heat of the fuel elements.
  • It is difficult to guarantee criticality safety if transuranic elements from nuclear waste or weapons stocks are to be incinerated. The sodium vapor bubble coefficient of the BN-800 can be positive ( minor actinides , pure MOX ) or negative (current hybrid core: MOX plus fuel elements made from enriched uranium) depending on the fuel composition . The RBMK had a positive void coefficient, which was a cause of the Chernobyl accident.

As an alternative to BN reactors, lead-cooled rapid reactors such as BREST are being built in Russia . According to a EURATOM study, these should have safety advantages compared to BN reactors.

Transmutation of nuclear waste

The BN series is intended to make a contribution to closing the fuel cycle, as transuranic waste can be split in the fast neutron spectrum. However, some transuranic elements of the nuclear waste worsen the criticality safety so drastically that only relatively small amounts of them may be present in the core. At present, a maximum of 20 kg / year of the minor actinides in the BN-800, which are particularly problematic in the garbage, could be converted by transmutation . This corresponds to the amount that a light water reactor generates about the same output per year. In order to split transurane waste (i.e. minor actinides) sensibly here, it would be necessary to replace half of the existing power plants with fast reactors. There is therefore a research project that will run from 2019 to 2034, which will examine whether a larger amount can be processed. Analyzes from 2005 showed that in principle it would be possible to convert up to 90 kg / year of minor actinides if the core of the reactor only contained uranium-235 and the otherwise present uranium-238 through a placeholder (zirconium carbide, aluminum nitride or Magnesium oxide) would be replaced. In this case, the enrichment of uranium-235 does not change because it is mixed with the placeholder. A BN-800 equipped in this way could convert the annual minor actinides from five nuclear power plants of the 1 GW class into short-lived fission products.

The BN-800 is currently not used for the transmutation of transuranic waste, but of excess weapons plutonium (not classic nuclear waste), which does not pose any major problems, since the MOX fuel elements made from plutonium in the reactor core are diluted with fuel elements made from enriched uranium. Other components of the highly active nuclear waste such as long-lived fission products are also produced in the BN-800, but cannot be transmuted in the neutron spectrum of the BN-800 (see here ), so that the BN-800 remains a nuclear waste producer in this regard. It should be noted, however, that long-lived fission products (mainly technetium-99 and cesium-135) have a radiotoxicity several orders of magnitude lower than plutonium-239, uranium-235 and -238 or minor actinoids and, as beta emitters, can also be easily shielded. Long-lived fission products are particularly dangerous because they can form anionic compounds with high chemical mobility. Special care is therefore required here during final disposal.

Due to its ability to transmutate minor actionoids, the BN-800 is called a milestone in the solution of the nuclear waste problem and even as a "nuclear waste eater" by the nuclear energy-friendly association Nuklearia.

A transmutation project similar to the BN reactors, the Generation IV sodium reactor concept ASTRID developed by France with Japanese participation , was initially abandoned by the CEA in the summer of 2019 and postponed to the second half of the current century. A new project plan for Generation IV reactors has been announced for the end of 2019.

See also

Web links

Individual evidence

  1. ↑ IAEA Fast Reactors general information (English)
  2. ↑ a b c d world-nuclear.org, Fast Neutron Reactors
  3. ↑ WANO Beloyarsk NPP and Davis Besser NPP ( Memento from September 27, 2007 in the Internet Archive ) (English)
  4. ↑ http://www.iaea.or.at/inisnkm/nkm/aws/fnss/fulltext/28014313.pdf (link not available)
  5. ↑ https://www.neimagazine.com/features/featurea-new-breed-for-china-5919186
  6. ↑ INSC: Database - Overview of Fast Reactors in Russia and the Former Soviet Union ( Memento from July 3, 2006 in the Internet Archive ) (English)
  7. ↑ a b https://www.gen-4.org/gif/upload/docs/application/pdf/2019-01/gifiv_webinar_pakhomov_19_dec_2018_final.pdf
  8. ↑ https://www.rt.com/news/325593-fast-neutron-nuclear-reactor/
  9. ↑ Russia connects BN-800 fast reactor to grid , World Nuclear News, December 11, 2015
  10. ↑ Groundbreaking Fast Neutron Reactor reaches full power , Cape Business News, September 12, 2016
  11. ↑ Rusia ensaya un prototipo del reactor nuclear del futuro , Sputnik Mundo, September 2, 2016
  12. ↑ http://www.world-nuclear-news.org/NN-Russias-BN-800-unit-enters-commercial-operation-01111602.html
  13. ↑ https://carnegieendowment.org/2017/02/17/rethinking-china-s-fast-reactor-pub-68079
  14. ↑ http://www.neimagazine.com/news/newsrussias-bn-1200-fast-reactor-envisaged-for-2019-4933888
  15. ↑ http://www.world-nuclear-news.org/Articles/Rosatom-postpones-fast-reactor-project-report-say
  16. ↑ Sodium-NaK Engineering Handbook Volume 1-6 1972
  17. ↑ a b c https://www.degruyter.com/downloadpdf/j/nuka.2015.60.issue-1/nuka-2015-0034/nuka-2015-0034.pdf
  18. ↑ IAEA-CN-245-05 (2017) https://media.superevent.com/documents/20170620/11795dbfabe998cf38da0ea16b6c3181/fr17-405.pdf
  19. ^ "Sodium Fast Reactors with Closed Fuel Cycle", chapter 12.2, by Baldev Raj, P. Chellapandi, PR Vasudeva Rao, CRC Press (2015)
  20. ↑ http://ecolo.org/documents/documents_in_english/SFRvsLFR-05.pdf
  21. ↑ https://www.nap.edu/read/11320/chapter/8
  22. ↑ https://www.ifnec.org/ifnec/upload/docs/application/pdf/2018-12/5.3_rosatom_khaperskaya.pdf Slides 17 and 23
  23. ↑ The Use of Sodium-Cooled Fast Reactors for Effectively Reprocessing Plutonium and Minor Actinides [1]
  24. ↑ Long-lived Fission Products, www.radioactivity.eu, accessed on December 18, 2019 [2]
  25. ↑ https://nuklearia.de/2016/12/09/strom-aus-atommuell-schneller-reaktor-bn-800-im-kommerzielle-leistungsbetrieb/
  26. ↑ https://nuklearia.de/2015/12/14/nukleare-meilensteine-erreich/
  27. ↑ France cancels ASTRID fast reactor project, September 2, 2019 https://www.neimagazine.com/news/newsfrance-cancels-astrid-fast-reactor-project-7394432
  28. ↑ France drops plans to build sodium-cooled nuclear reactor, Reuters, August 30, 2019 [3]