Natural uranium reactor

This article describes the technical construction. For uranium deposits, which were critical in geological times, see the Oklo natural reactor .

A natural uranium reactor is a nuclear reactor that works with natural, i.e. non- enriched uranium as a nuclear fuel .

Drawing of the Chicago Pile 1 , the first nuclear reactor to achieve criticality in 1942

use

The first experimental test reactors from the 1940s and 1950s, but also some commercial power reactors , especially in Great Britain , France , Canada and India , used natural uranium. In Germany , research reactor 2 , the Niederaichbach nuclear power plant and the Karlsruhe multi-purpose research reactor were operated with natural uranium. Today (2020) natural uranium is still used for energy production in around 50 reactors of the CANDU type.

Physical background

In natural uranium, the proportion of the easily fissile uranium isotope ²³⁵ U is around 0.7%. In a reactor with natural uranium fuel, criticality , i.e. a self-sustaining nuclear fission chain reaction , cannot be achieved with every, but only with certain moderator substances; With the most economical moderator and coolant, ordinary water (light water), it does not work because too many neutrons are lost through absorption. All natural uranium reactors are therefore either heavy water reactors or graphite-moderated reactors. Either pure uranium metal (U) or uranium dioxide (UO ₂ ) is used as fuel .

Most of today's nuclear power plants use enriched uranium with a ²³⁵ U content of 0.7% to 2%, with some reactor types up to 20%. Highly enriched uranium (20% to 93% ²³⁵ U) is used in a few research reactors and in nuclear weapons .

In the Oklo natural reactor and other uranium deposits in Gabon , critical nuclear fission chain reactions with natural uranium took place around two billion years ago. At that time, the proportion of ²³⁵ U in natural uranium was around 3%, so that the criticality could arise even with moderation with normal water.

Commercial power reactors

The following nuclear power plants were or are operated with natural uranium. In the case of nuclear power plants with several units, the first unit is indicated under “Start of operation” and that of the last unit under “End of operation”, and that of the most powerful unit under “Output”.

Magnox reactors

Scheme of a Magnox reactor

Magnox reactors ( engl. Magnesium Alloy Graphite Moderated Gas Cooled Reactor Uranium oxides ) are graphite-moderated nuclear reactors with carbon dioxide (CO ₂ to be cooled). The fuel elements consist of natural uranium in metallic form, which is coated with a magnesium - aluminum alloy.

Magnox reactors were developed in the UK and were among the first commercial nuclear reactors in the world. The design was implemented in 26 UK reactors and two nuclear power plants in Italy and Japan . Today there is no longer a Magnox reactor in operation; the last remaining reactor was shut down at the Wylfa nuclear power plant on December 30, 2015.

As a successor to the Magnox reactor, the Advanced Gas-cooled Reactor was developed in Great Britain in the 1960s, but it uses uranium dioxide enriched to around 3% as a nuclear fuel.

Surname	country	power	operating beginning	operating end	Remarks
Calder Hall 1-4	Great Britain	50 MW	Aug 1956	Mar 2003	First nuclear power plant used commercially to generate electricity, it was also used to generate plutonium
Chapelcross 1-4	Great Britain	50 MW	Feb 1959	Jun 2004	was built and used parallel to Calder Hall
Berkeley 1-2	Great Britain	138 MW	Jun 1962	Mar 1989	first nuclear power plant in the UK built for commercial use only
Bradwell 1-2	Great Britain	123 MW	Jul 1962	Mar 2002
Latina	Italy	153 MW	May 1963	Dec 1987	was shut down in the train of Italy's nuclear phase-out
Hunterston A1-A2	Great Britain	150 MW	Feb 1964	Mar 1990
Trawsfynydd 1-2	Great Britain	159 MW	Jan 1965	Feb 1991
Hinkley Point A1-A2	Great Britain	235 MW	Feb 1965	May 2000
Dungeness A1-A2	Great Britain	225 MW	Sep 1965	Dec 2006
Tōkai	Japan	159 MW	Nov 1965	Mar 1998
Size wave A1-A2	Great Britain	210 MW	Jan 1966	Dec 2006
Oldbury A1-A2	Great Britain	217 MW	Nov 1967	Feb 2012
Wylfa 1-2	Great Britain	490 MW	Jan 1971	Dec 2015

UNGG reactors

The two UNGG reactor blocks in the Saint-Laurent nuclear power plant

The UNGG reactors ( French Uranium Naturel Graphite Gaz ), which were developed in France in the 1950s and 1960s , were similar in design to the Magnox reactors and were moderated with graphite and cooled with carbon dioxide. The fuel elements in UNGG reactors were also made of natural uranium, but here they were coated with a magnesium- zirconium alloy. UNGG reactors were used in eight French nuclear reactors and in the Spanish nuclear power plant Vandellòs , none of the reactors is now in operation.

The UNGG design has been replaced in France by pressurized water reactors , all of which are operated with enriched uranium.

Surname	country	power	operating beginning	operating end	Remarks
Marcoule G1-G3	France	40 MW	Sep 1956	Jun 1984
Quinone A1-A3	France	360 MW	Jun 1963	Jun 1990
Saint-Laurent A1-A2	France	515 MW	Mar 1969	May 1992	Incident (INES 4)
Bugey 1	France	540 MW	Apr 1972	May 1994
Vandellòs 1	Spain	480 MW	May 1972	Jul 1990	was switched off permanently after a fire in October 1989

CANDU reactors

The Pickering nuclear power plant with eight CANDU reactors

→ See also: List of CANDU reactors

The CANDU reactor was developed in Canada . CANDU reactors use heavy water as a moderator and also (in a separate circuit with overpressure) as a coolant. Natural uranium or slightly enriched uranium can be used as nuclear fuel.

The reactor type is used in many countries, especially Canada, but also in Argentina , China , Pakistan , Romania and South Korea . 34 of the 36 CANDU reactors are still in operation today.

The Advanced CANDU Reactor is an evolution of the CANDU design, which uses slightly enriched uranium.

Surname	country	power	operating beginning	operating end	Remarks
Rolphton	Canada	22 MW	Jun 1962	Aug 1987	Prototype for CANDU reactors
Douglas Point	Canada	206 MW	Jan 1967	May 1984	Canada's first commercially operated nuclear power plant
Pickering 1-8	Canada	516 MW	Apr 1971
Gentilly 1-2	Canada	635 MW	Apr 1971		Unit 1 was a prototype for the heavy boiling water reactor
Rajasthan 1	India	90 MW	Nov 1972
Karachi	Pakistan	125 MW	Dec 1972
Bruce 1-8	Canada	822 MW	Sep 1976
Wolsong 1-4	South Korea	685 MW	Dec 1982
Point Lepreau	Canada	635 MW	Feb 1983
Embalse	Argentina	600 MW	Apr 1983
Darlington 1-4	Canada	878 MW	Jan 1990
Cernavoda 1-2	Romania	650 MW	Jul 1996		only nuclear power plant in Romania
Qinshan 3-1,3-2	China	650 MW	Nov 2002

Further heavy water pressure reactors

Niederaichbach nuclear power plant

Most nuclear reactors in India are heavy water-pressure reactors ( Engl. Pressurized Heavy Water Reactor ), which are operated with natural uranium and based on the CANDU design. All 16 reactors are still in operation.

The Niederaichbach nuclear power plant in Germany , a heavy water moderated pressure tube reactor with CO ₂ gas cooling, and the multi-purpose research reactor Karlsruhe , a pressure tube reactor moderated and cooled with heavy water, were also operated with natural uranium . Both plants have now been shut down. The multi-purpose research reactor served as a prototype for the Argentine nuclear power plant Atucha 1, which is still in operation today and now uses slightly (0.85%) enriched uranium for reasons of efficiency.

The R3 reactor at Ågesta nuclear power plant in Sweden was a pressure vessel reactor developed as part of the so-called "Swedish Line", which aimed to achieve independence from abroad through the use of indigenous, non-enriched uranium fuel elements; the later Swedish nuclear power plants, however, were light water reactors operated with enriched uranium. Reactor A1 in the Czechoslovakian nuclear power plant Bohunice was a gas-cooled prototype pressure tube reactor that was developed jointly with Russia and also operated with natural uranium. These two reactors have now also been shut down.

Surname	country	power	operating beginning	operating end	Remarks
Ågesta	Sweden	10 MW	May 1964	Jun 1974	first Swedish nuclear power plant
MZFR Karlsruhe	Germany	52 MW	Sep 1965	May 1984	was also used as a research reactor
Bohunice A1	Czechoslovakia	93 MW	Dec 1972	May 1979	first Czechoslovak nuclear power plant
Niederaichbach	Germany	100 MW	Jan 1973	Jul 1974	was only in operation for 18 months
Atucha 1	Argentina	100 MW	Mar 1974		today uses slightly (0.85%) enriched uranium
Rajasthan 2-6	India	202 MW	Nov 1980
Madras 1-2	India	202 MW	Jul 1983
Narora 1-2	India	202 MW	Jul 1989
Kakrapar 1-2	India	202 MW	Nov 1992
Kaiga 1-4	India	202 MW	Dec 1999
Tarapur 3-4	India	490 MW	Mar 2000

Experimental and research reactors

Examples of experimental and research reactors that were or are operated with natural uranium are:

Graphite-moderated reactors

Surname	country	power	operating beginning	operating end	Remarks
Chicago Pile 1	United States	0.5 W	Feb 1942	Mar 1943	first nuclear reactor in which a controlled critical nuclear chain reaction took place
Chicago Pile 2	United States	2 w	Mar 1943	1954	The Chicago Pile 1 was rebuilt in the Red Gate Woods (first Argonne National Laboratory ) as Chicago Pile 2.
F-1	Russia	24 W.	Dec 1946		was operated with natural uranium as well as with 2% enriched uranium
GLEEP	Great Britain	50 W	Aug 1947	Sep 1990	first nuclear reactor in Western Europe
BR-1	Belgium	4 MW	May 1956
Marius	France	400 W	1960	Apr 1983
BEPO	Great Britain	6.5 MW	1962	1968
Cesar	France	10 W	Dec 1964	Aug 1977

Heavy water moderated reactors

Surname	country	power	operating beginning	operating end	Remarks
Chicago Pile 3	United States	300 W	May 1944	1954	first heavy water reactor
Haigerloch	Germany	-	(Mar 1945)	(Apr 1945)	did not achieve any criticality
ZEEP	Canada	10 W	Sep 1945	Oct 1970	first operational nuclear reactor outside of the United States
NRX	Canada	25 MW	Jul 1947	Mar 1993	For several years the most powerful nuclear reactor in the world
ZOÉ	France	0.1 MW	Dec 1948	1974
EL-2	France	2 MW	1952	1965
R1	Sweden	0.6 MW	Jul 1954	1970
Aquilon	France	18 MW	1956	?
NRU	Canada	200 MW	Nov 1957		was switched to highly enriched uranium in 1964 and to weakly enriched uranium in 1991
RB	Serbia	0 W	Apr 1958		was later switched to highly enriched uranium
CIRUS	India	40 MW	Jul 1960
ZED-2	Canada	200 W	Sep 1960
Diorite	Switzerland	30 MW	Oct 1960	1977
FR 2	Germany	12 MW	Mar 1961	Dec 1981	first nuclear reactor in Germany that was built according to its own concept; was switched to weakly enriched uranium in 1966
JRR-3	Japan	10 MW	1962	1983
ESSOR	European Union	43 MW	Mar 1967	Jun 1983	The location was Ispra , Italy
TRR	Taiwan	40 MW	Jan 1973	1988
Dhruva	India	100 MW	Aug 1985

Military nuclear facilities

The Hanford B reactor

All of today's nuclear powers (USA, Russia, Great Britain, France and the People's Republic of China, as well as India, Pakistan, Israel and North Korea) initially used natural uranium reactors to produce weapons- grade plutonium . The infrastructure for the production of nuclear weapons was created in some large-scale nuclear programs (see e.g. Manhattan Project , Force de frappe , Soviet atomic bomb project , China’s first research station for nuclear weapons and North Korean nuclear weapons program ). The first of these reactors from the 1940s and 1950s have now been shut down.

In the following military nuclear facilities , natural uranium reactors were used to produce plutonium.

Surname	country	Number of reactors	Total output	operating beginning	operating end	Remarks
Hanford Site	United States	3	750 MW	Jun 1943	Jun 1965	The plutonium produced was used for the Fat Man atomic bomb , which was dropped on the Japanese city of Nagasaki on August 9, 1945 .
Mayak	Russia	7th	63 MW	Jun 1948	1990	On September 29, 1957, one of the three most serious nuclear accidents in history occurred there.
Sellafield	Great Britain	2	360 MW	Oct 1950	Oct 1957	The Pile No. 1 and Pile No. 2 reactors were shut down after the Windscale fire in October 1957.
Tomsk	Russia	5	45 MW	1955	Jun 2008	One of the three reactors (ADE-5) was also used for electricity and district heating.
Marcoule	France	3	80 MW	Sep 1956	Jun 1984	The three reactors G1 to G3 (see above) also provided power.
Zheleznogorsk	Russia	3	27 MW	Aug 1958	Apr 2010	One of the three reactors (ADE-2) was also used for power and district heating.
Bhabha	India	2	140 MW	Jul 1960		The two reactors CIRUS and Dhruva (see above) are officially declared as research reactors.
Dimona	Israel	1	24 MW	1964		With French help, it was constructed identically to the G1 reactor. The Israeli government has so far neither confirmed nor denied that this is a military facility for the production of plutonium.
Jiuquan	China	1	250 MW	Oct 1966		The reactor was built with Soviet help.
Nyŏngbyŏn	North Korea	1	25 MW	Aug 1985		The Experimental Power Reactor was built without British support based on the approved construction plans of the Magnox reactors of the Calder Hall nuclear power plant , it was also used to generate electricity (about 5 MWe).
Khushab	Pakistan	1	50 MW	Apr 1998		The reactor was developed independently, Saudi Arabia co-financed the project (see Saudi Arabia's nuclear program ).

See also

• List of nuclear power plants
• List of nuclear facilities
• List of the most powerful nuclear reactors

literature

• Kenneth Kok (Ed.): Nuclear Engineering Handbook . CRC Press, 2009, ISBN 978-1-4200-5390-6 (English).

Web links

• Power Reactor Information System on the website of the International Atomic Energy Agency
• Research Reactor Database on the website of the International Atomic Energy Agency
• Reactor Database on the World Nuclear Association website

supporting documents

1. ^ Institution of Engineering and Technology: Nuclear Reactor Types. (No longer available online.) May 2008, formerly in the original ; Retrieved December 25, 2009 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
2. ^ World Nuclear Association: Nuclear Power Reactors. April 2009, accessed 26 December 2009 . 
3. ↑ Alex P. Meshik: Natural Nuclear Reactors . In: Spectrum of Science . tape 2006/06 , 2006, pp. 84-90 ( Spektrum.de ).
4. ^ European Nuclear Society: Magnox reactor. Retrieved December 25, 2009 . 
5. ↑ Mary Byrd Davis: Natural uranium graphite gas reactors (UNGG) ( Memento of the original from December 9, 2008 in the Internet Archive ) 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. , Nuclear France: Materials and Sites, WISE-Paris, 2002. 
6. ^ CANDU Owners Group Inc .: CANDU Reactors. (No longer available online.) Archived from the original on February 25, 2012 ; Retrieved December 25, 2009 . 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.  
7. ^ ^{A b c} Rodney W. Jones, Mark G. McDonough: Tracking Nuclear Proliferation: A Guide in Maps and Charts, 1998 . Carnegie Endowment for International Peace, 1998, 6. India Map and Chart ( carnegieendowment.org [PDF]). carnegieendowment.org ( Memento of the original dated August 11, 2009 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.  
8. ↑ Federal Office for Radiation Protection : Nuclear Plant Decommissioning September 2009. (PDF) (No longer available online.) September 2009, formerly the original ; Retrieved December 25, 2009 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
9. ^ Enrico Fermi : The Development of the First Chain Reaction Pile . In: Proceedings of the American Philosophy Society . No. 90 , 1946, pp. 20-24 .
10. ^ Argonne National Laboratory : Chicago Pile 2. Retrieved December 28, 2009 . 
11. ^ Nuclear Threat Initiative: Russia: Kurchatov Institute. July 8, 2004, accessed December 28, 2009 . 
12. ^ Research Sites Restoration: Harwell Achievements. (No longer available online.) Archived from the original on February 17, 2015 ; accessed on December 28, 2009 . 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.  
13. ↑ SCK • CEN : BR1 - 50th Anniversary. (No longer available online.) Archived from the original on March 13, 2016 ; accessed on December 28, 2009 . 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.  
14. ↑ ^{a b} Mary Byrd Davis: Provence-Alpes-Cote-d'Azur ( Memento of the original from January 6, 2009 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. , Nuclear France: Materials and Sites, WISE-Paris, 2002. 
15. ↑ Curtains for BEPO  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , Nuclear Engineering International, February 20, 2009.  
16. ↑ Werner Heisenberg : About the work on the technical exploitation of nuclear energy in Germany . In: Natural Sciences . No. 33 , 1946, pp. 325-329 .
17. ^ Canadian Nuclear Association: ZEEP. (No longer available online.) 2008, archived from the original on March 13, 2011 ; Retrieved December 25, 2009 . 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.  
18. ^ Canadian Nuclear Association: National Research Experimental. 2008, accessed December 25, 2009 . 
19. ^ Mary Byrd Davis: Center de Fontenay-aux-Roses ( Memento of February 25, 2013 in the Internet Archive ), Nuclear France: Materials and Sites, WISE-Paris, 2002.
20. ^ ^{A b} Mary Byrd Davis: Center de Saclay ( Memento of April 29, 2007 in the Internet Archive ), Nuclear France: Materials and Sites, WISE-Paris, 2002.
21. ^ Vattenfall : The development of Swedish nuclear power plants. (PDF) September 15, 2009, accessed December 31, 2009 . 
22. ^ Canadian Nuclear Association: National Research Universal. (No longer available online.) 2008, archived from the original on October 18, 2009 ; Retrieved December 25, 2009 . 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.  
23. ↑ Atomic Energy of Canada: AECL's NRU Reactor
24. ↑ Peter Hug: Atomic Energy. In: Historical Lexicon of Switzerland . April 20, 2011 , accessed July 2, 2019 .
25. ^ Information circle on nuclear energy: History of nuclear research. (No longer available online.) Archived from the original on December 28, 2009 ; Retrieved December 25, 2009 . 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.  
26. ↑ Fusao Nakayama: Japanese Experience with Shipment of Research Reactor Spent Fuel , IAEA / USA Interregional Training Course, 13.-24. January 1997.
27. ^ Chungshan , GlobalSecurity.org
28. ^ Hanford site history
29. ↑ Mary Byrd Davis: Languedoc-Roussillon ( Memento of the original from February 17, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Nuclear France: Materials and Sites, WISE-Paris, 2002. 
30. ^ Israel - Nuclear Weapons , GlobalSecurity.org
31. ^ David Wright, Lisbeth Gronlund: A History of China's Plutonium Production . In: Science and Global Security . No. 11 , 2003 (English, ucsusa.org [PDF; 239 kB ]).
32. ^ World Nuclear Association: Nuclear Power in Korea. December 16, 2009. Retrieved December 26, 2009 . 
33. ↑ Pakistan's Indigenous Nuclear Reactor Starts Up . Islamabad The Nation, April 13, 1998.