12 Nuclear reactors
There are just under 100 operating commercial reactors in the United States.
The first reactors
The first man made reactor was constructed at University of Chicago in 1942. It was made of uranium and graphite blocks with cadmium coated control rods.
The Hanford B Reactor is the same ‘pile’ design. It was used to produce plutonium during the Cold War.
Natural reactors
A natural reactor actually happened about 2 billion years ago. Sixteen sites operated for about [latex]10^5[/latex] years at 100 kW thermal energy. Uranium rich mineral deposits were infiltrated by groundwater which served as moderator.
EBR-I was the first reactor to generate electricity in 1951. It is now a museum, open to the public for free from Memorial Day to Labor Day. EBR-I was a breeder reactor and the first of its kind. This proved Fermi’s theory that a reactor can be build to generate fissile material.
EBR-II
EBR-II is an sodium fast reactor design for 62.5 MW that operated from 1964 to 1994. It produced 19 MW electricity operated for 30 years with no accidents. EBR-II was also a breeder reactor that reprocessed fuel onsite by pyroprocessing. The design featured the most advanced passive safety systems.
TREAT
TREAT is an air cooled, graphite moderated thermal reactor that operated from 1959 to 1994. It was used for transient reactor tests to simulate all sorts of reactor accidents. The reactor can generate neutron pulses up to 19 GW. It was restarted in 2018 to support the Accident Tolerant Fuel program.
Military
Nuclear reactors are used on submarines and aircraft carriers. The lifecycle of the reactors is about 30 years. The first nuclear powered submarine was the Nautilus, launched in 1954, with a 25 year life span. The reactor designs are classified, but they are known to be light water reactors.
Additional notes