Experimental Breeder Reactors I and II

Ashwin Kumar
February 14, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: The first power reactor, Experimental Breeder Reactor Number 1. Located in Idaho. (Source: Wikimedia Commons)

The Experimental Breeder Reactor Number 1, also known as EBR-I (see Fig. 1), was created shortly following World War II, with its construction beginning in 1949. Construction was completed surprisingly quickly, with the plant beginning power operation on August 24, 1951. On December 20, 1951, atomic energy was finally successfully harvested at this plant. While the plant did successfully produce power, this was not its main purpose. The plant was originally built in order to validate a nuclear physics theory that a breeder reactor should be possible. [1] This theory was validated in 1953, when scientists confirmed that the reactor was producing fuel through a fission process. EBR-I was significant not only because it was the world's first plant to generate electricity from atomic energy, but also because it was the first to use plutonium fuel to generate electricity. EBR-I was finally deactivated in 1964, at which point plans had been put into place for it to be replaced by EBR-II.


The Experimental Breeder Reactor Number 2 (EBR-II) was created to replace EBR-I in the mid 1960s. The initial purpose of EBR-II was "to demonstrate a complete breeder-reactor power plant with on-site reprocessing of metallic fuel". [2] Once this experiment was successfully completed, researchers repurposed the reactor to experiment with alternate fuels, materials, and reactor components. Over the course of 30 years, in addition to being a research site for nuclear scientists, the reactor produced over two billion kilowatt-hours of electricity.

Safety Features of EBR-II

EBR-II was also designed with state-of-the-art safety facilities. In a 1986 experiment, scientists tested these features. They first ran the reactor at full capacity, and manually turned off the automatic emergency response systems. Then, they cut the electricity supply, which caused the cooling pumps to fail. This situation is actually worse than what happened in the Fukushima Nuclear Disaster, in which the automatic emergency response system was able to turn off the reactor prior to the reactor's losing power. Luckily, EBR-II was able to respond more positively, in which the reactor was automatically shut down by a sensor that determined the temperature was getting dangerously high, and released a large pool of sodium to flood the reactor. [2] The sodium took so long to heat up that it was able to prevent the reactor from a complete meltdown.

© Ashwin Kumar. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] R. Michel, "Fifty Years Ago in December: Atomic Reactor EBR-I Produced First Electricity" Nuclear News 44, No. 12, 28 (November 2001).

[2] C. Westfall, "Vision and Reality: The EBR-II Story," Nuclear News 47, No. 2, 25 (February 2004).