Element · U

Uranium

An element used as a yellow glass colourant for a century before anyone knew it was radioactive.

Uranium was identified in 1789 and used through the nineteenth century to give glass and ceramic glaze a distinctive yellow-green. Its radioactivity was not discovered until 1896, and its capacity for fission not until 1938.

As a material it is dense — about seventy percent denser than lead — and that property alone gives depleted uranium uses in counterweights and armour that have nothing to do with nuclear physics.

Economic significance

Uranium's value is almost entirely a function of enrichment, since the fissile isotope makes up only 0.7% of natural uranium. The industry is therefore built around separation technology rather than around mining, which is a pattern it shares with very few other materials.

Uses

Uranium's use is overwhelmingly nuclear fuel. Enriched to a few per cent uranium-235, it fuels the reactors that generate a significant share of the world's low-carbon electricity; enriched much further, it makes weapons, which is why the enrichment technology is among the most tightly controlled in existence.

Depleted uranium — the leftover, mostly uranium-238 — is very dense and is used for radiation shielding, aircraft counterweights and armour-piercing munitions, the last of which remains contested.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is a source for

Actinium — element
Promethium — element
Polonium — element
Plutonium — element · formed from uranium-238 in a reactor and recovered from spent fuel
Radium — element
Radon — element
Vanadium — element · and from uranium processing, where it occurs in the same ores

is used as

Nuclear fuel — application · after enrichment, since the fissile isotope is 0.7% of natural uranium

is extracted from

Uraninite — mineral · the principal uranium ore, and the pitchblende the Curies worked Wikidata

is produced by

Solvent extraction and electrowinning — process · as yellowcake rather than metal: leaching and solvent extraction end at a uranium oxide concentrate, and the metal is several conversion steps further on

is an input to

Neutron irradiation — process · uranium-238 is the feedstock for everything heavier: it absorbs neutrons without fissioning, which is what starts the sequence

is found in

Seawater — material · at three parts per billion, which is four billion tonnes in total and has defeated every extraction scheme proposed for it
Uraninite — mineral Wikidata

is an alternative to

Thorium — element · as nuclear fuel: thorium is three times as abundant, produces far less long-lived waste, and is not fissile — it has to be bred into uranium-233 first, which is why every thorium programme is a proposal and every uranium one is a power station

is associated with

The wartime materials programmes — event · isotope separation was a materials problem before it was a physics one

Sources

Material World
Our own writing
Wikidata
Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
PubChem
US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
NIST — National Institute of Standards and Technology
United States Department of Commerce · US Government work — public information, credit requested