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 mi southeast of Arco, Idaho. It was the world's first breeder reactor. 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. 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.

History
As part of the National Reactor Testing Station (since 2005 Idaho National Laboratory), EBR-I's construction started in late 1949. The reactor was designed and constructed by a team led by Walter Zinn at the Argonne National Laboratory Idaho site, known as Argonne-West. In its early stages, the reactor plant was referred to as Chicago Pile 4 (CP-4) and Zinn's Infernal Pile. 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, EBR-I produced electricity for its first time. The following day, the reactor produced enough power to light the whole building. The EBR-I produced 200 kW of electricity out of 1.4 MW of heat generated by the reactor.

The production of electricity at EBR-I is the first time that a reactor created in-house available electricity, and it is sometimes misreferred to as the first time that a nuclear reactor has ever created electricity. However, the world's first electricity produced by a nuclear reactor occurred during an experiment 3 years earlier in September 1948 at the X-10 Graphite Reactor at the Oak Ridge National Lab in Tennessee. Later in 1955, another nuclear milestone was reached when an experimental boiling water reactor plant called BORAX-III (also designed, built, and operated by Argonne National Laboratory) was connected to external loads, powering the nearby city of Arco, Idaho, the first time a city had been powered solely by nuclear power.

The design purpose of EBR-I was not to produce electricity but instead to validate nuclear physics theory that 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.

Besides being one of the world's first to generate 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-I's initial purpose was to prove Enrico Fermi's fuel breeding principle, a principle that a nuclear reactor can produce more fuel atoms than it consumes. EBR-I proved this principle.

Design
EBR-I used uranium metal fuel and NaK primary coolant. It was in this identical to the initial configuration of the later Dounreay Fast Reactor which first went critical in 1959.

The primary liquid metal coolant flows by gravity from the supply tank through the reactor core, where it absorbs heat. Then, the coolant flows to heat the exchanger, where it gives up this heat to the secondary coolant, another liquid metal. The primary coolant is returned to the supply tank by an electromagnetic pump. The secondary coolant is pumped to the boiler, where it gives up its heat to water, generating steam. This steam passes to the turbine, which is how electricity is produced. This steam then condenses and returned to the boiler by a water pump.

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

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