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Experimental Breeder Reactor I

Experimental Breeder Reactor I (EBR-I) is a decommissioned research reactor and U.S. National Historic Landmark located in the desert about 18 miles (29 km) southeast of Arco, Idaho. It was the world's first breeder reactor.[3] At 1:50 p.m. on December 20, 1951, it became one of the world's first electricity-generating nuclear power plants when it produced sufficient electricity to illuminate four 200-watt light bulbs.[4][5] Electricity had earlier been generated by a nuclear reactor on September 3, 1948 at the X-10 Graphite Reactor in Oak Ridge, Tennessee.[6][7][8] EBR-I subsequently generated sufficient electricity to power its building, and continued to be used for experimental purposes until it was decommissioned in 1964. The museum is open for visitors from late May until early September.

Experimental Breeder Reactor No. 1
EBR-1, August 2012.jpg
Experimental Breeder Reactor Number 1 in Idaho, the first power reactor.
Experimental Breeder Reactor I is located in Idaho
Experimental Breeder Reactor I
Experimental Breeder Reactor I is located in the US
Experimental Breeder Reactor I
Location Butte County, Idaho, US
Nearest city Arco, Idaho
Coordinates 43°30′41″N 113°00′23″W / 43.51132°N 113.0064°W / 43.51132; -113.0064Coordinates: 43°30′41″N 113°00′23″W / 43.51132°N 113.0064°W / 43.51132; -113.0064
Built 1950
Architect Atomic Energy Commission
NRHP reference # 66000307
Significant dates
Added to NRHP October 15, 1966[1]
Designated NHL December 21, 1965[2]



As part of the National Reactor Testing Station (now Idaho National Laboratory), EBR-I's construction started in late 1949. The reactor was designed by a team led by Walter Zinn at the Argonne National Laboratory. In its early stages, the reactor plant was referred to as Chicago Pile 4 (CP-4) and Zinn's Infernal Pile.[9] Installation of the reactor at EBR-I took place in early 1951 (the first reactor in Idaho) and it began power operation on August 24, 1951. On December 20 of that year, atomic energy was successfully harvested at EBR-1 for the first time. The following day, the reactor produced enough power to light the whole building. The power plant produced 200 kW of electricity out of 1.4 MW of heat generated by the reactor.[10]

Part of the core after the 1955 partial meltdown

The design purpose of EBR-I was not to produce electricity but instead to validate nuclear physics theory which suggested that a breeder reactor should be possible. In 1953, experiments revealed the reactor was producing additional fuel during fission, thus confirming the hypothesis. On November 29, 1955, the reactor at EBR-I suffered a partial meltdown during a coolant flow test. The flow test was trying to determine the cause of unexpected reactor responses to changes in coolant flow. It was subsequently repaired for further experiments, which determined that thermal expansion of the fuel rods and the thick plates supporting the fuel rods was the cause of the unexpected reactor response.[11]

Although EBR-I produced the first electricity available in-house, a nearby reactor plant called BORAX-III was connected to external loads, powering the nearby city of Arco, Idaho in 1955, the first time a city had been powered solely by nuclear power.[12]

Besides generating the world's first electricity from atomic energy, EBR-I was also the world's first breeder reactor and the first to use plutonium fuel to generate electricity (see also the Clementine nuclear reactor). EBR-1's initial purpose was to prove Enrico Fermi's fuel breeding principle, a principle that showed a nuclear reactor producing more fuel atoms than consumed. Along with generating electricity, EBR-1 would also prove this principle.[13]

Decommission and legacyEdit

EBR-I was deactivated in 1964 and replaced with a new reactor, Experimental Breeder Reactor II.

It was declared a National Historic Landmark in 1965[2][14] with its dedication ceremony held on August 25, 1966, led by President Lyndon Johnson and Glenn T. Seaborg.[15] It was also declared an IEEE Milestone in 2004.[16]


See alsoEdit


  1. ^ National Park Service (2007-01-23). "National Register Information System". National Register of Historic Places. National Park Service. 
  2. ^ a b "Experimental Breeder Reactor No. 1". National Historic Landmark summary listing. National Park Service. Retrieved February 6, 2008. 
  3. ^ "Breeder reactor". Encyclopedia Britannica. Retrieved 2017-12-31. 
  4. ^ Experimental Breeder Reactor 1, Argonne National Laboratory
  5. ^ Fifty years ago in December: Atomic reactor EBR-I produced first electricity American Nuclear Society Nuclear news, November 2001
  6. ^ "Graphite Reactor". October 31, 2013. 
  7. ^ "Graphite Reactor Photo Gallery". October 31, 2013. 
  8. ^ "First Atomic Power Plant at X-10 Graphite Reactor". October 31, 2013. 
  9. ^ Argonne’s Nuclear Science and Technology Legacy: Chicago Pile reactors create enduring research legacy part of the Argonne National Laboratory Highlights in the period 1942–1949
  10. ^ Nuclear energy for peace: the birth of nuclear energetics
  11. ^ The Story of the Borax Nuclear Reactor and the EBR-I Meltdown — Ray Haroldsen ISBN 978-1-56684-706-3
  12. ^ "AEC Press release for BORAX-III lighting Arco, Idaho". U.S. Department of Energy, Argonne National Laboratory. 1999. Retrieved July 26, 2012. 
  13. ^ "Experimental Breeder Reactor I". ASME. Retrieved December 18, 2017. 
  14. ^ Blanche Higgins Schroer (June 12, 1976). "National Register of Historic Places Inventory-Nomination: Experimental Breeder Reactor #1" (PDF). National Park Service. Retrieved June 22, 2009.  and Accompanying 4 photos, from 1975. (1.43 MB)
  15. ^ "EBR-I now open to the public for tours". Idaho National Laboratory. May 26, 2016. Retrieved December 18, 2017. 
  16. ^ "Milestones:Experimental Breeder Reactor I, 1951". IEEE Global History Network. IEEE. Retrieved August 3, 2011. 

External linksEdit