Technology & Medicine › Atomic & space age › Nuclear energy (bombs and reactors)
Nuclear power stations
1954 (Obninsk); 1956 (Calder Hall)· Invention or discovery· Tools, energy & materials
Well documentedSolid records, physical evidence or scientific consensus.
Nuclear power stations use the heat of a controlled chain reaction to boil water and drive turbines that make electricity.
See it on the Technology & Medicine map →How it works
A reactor works like a coal plant with a different heat source: fission heats water into steam, which spins a turbine and generator. The Soviet Obninsk plant first fed a grid in June 1954; Britain's Calder Hall (1956) was the first at commercial scale, and the US followed at Shippingport (1957). By 2024 about 440 reactors in some 30 countries supplied around 9% of the world's electricity. South Korea runs about 26 and exports reactors.
Why it mattered
It gives steady, low-carbon power, but cost overruns, waste storage and accidents at Three Mile Island, Chernobyl and Fukushima have slowed its growth.
Think of it like
Same turbine hall as a coal plant; only the boiler room differs, and it is far more tightly regulated.
How we know
IAEA and World Nuclear Association reactor databases, plant operating records and national grid statistics.
Still unknown or debated
Whether new small modular reactors can cut costs enough to revive building, and where to store waste for thousands of years, remain open questions.
Inside this (1)
Connections (3)
▸Nuclear energy (bombs and reactors) was turned to electricity in Nuclear power stationsWell documented
The connection
The first big reactors were built to make plutonium for bombs, and their heat was wasted. Engineers soon used such heat to boil water and drive turbines. President Eisenhower's 1953 'Atoms for Peace' speech promoted civilian power, and US submarine reactors, starting with USS Nautilus in 1955, became the model for most power plants.
When and how
EBR-I in Idaho lit bulbs with nuclear electricity in December 1951; Obninsk, USSR, 1954; Calder Hall, England, 1956; Shippingport, Pennsylvania, 1957.
How we know
Plant records and government histories trace power reactors directly to wartime reactors and the naval program led by Admiral Hyman Rickover.
Debates and open questions
Were early plants mainly for electricity or for weapons? Calder Hall also made plutonium for Britain's bombs, blurring the line.
▸Nuclear power stations suffered their worst accident at the Chernobyl disasterWell documented
The connection
Chernobyl's reactor 4 was an RBMK, a Soviet design cooled by water and slowed by graphite. Its flaw: if cooling water boiled into steam, power rose instead of falling. During a badly run test with safety systems switched off, power surged, the reactor exploded and the graphite burned. Most Western reactors lacked this flaw and had containment buildings.
When and how
Chernobyl plant near Pripyat, Soviet Ukraine, at 1:23 a.m. on April 26, 1986, during a test of whether spinning-down turbines could power pumps in a blackout.
How we know
The IAEA's safety reports (1986, revised 1992), Soviet investigations and later archives document the sequence; the 1992 report shifted much of the blame from operators to the design.
Debates and open questions
How to divide blame among operators, designers and Soviet secrecy is still argued, as is how it compares with Fukushima (2011); both are rated 7, the maximum on the international scale.
▸Nuclear power stations compete as low-carbon power with Cheap solar, batteries and electric carsMostly agreed
The connection
Nuclear plants, like wind and solar, make electricity with almost no carbon emissions, and they supplied about 9% of world electricity in 2023. But new reactors have become slow and costly to build while solar and wind costs fell sharply; wind and solar together passed nuclear output in 2021. Planners now weigh steady nuclear against cheaper, weather-dependent renewables plus batteries.
When and how
Worldwide since the 2010s; examples include Georgia's Vogtle reactors, finished in 2023–24, years late, and China, which builds both nuclear and renewables fastest.
How sure are we?
Cost comparisons by Lazard and the IEA; generation data from Ember; construction records of delayed projects such as Vogtle, Flamanville and Hinkley Point.
Debates and open questions
Whether small modular reactors will make nuclear cheaper, and what mix of nuclear and renewables gives the most reliable grid, is debated.