Highly Enriched Uranium is uranium that is more than 20 percent U-235. It is nuclear-weapon-usable uranium, compared to low-enriched uranium (LEU), which has less than 20% concentrated U-235. LEU is the recommended type of uranium for civilian nuclear programs; Iran’s stockpile of HEU is just one reason why Western governments doubt the country’s claim of pursuing nuclear power for peaceful purposes only.
- HEU is one of the main concerns of nuclear material security policy. Securing materials such as HEU in nuclear weapons states and non-nuclear weapons states alike—along with proper disposal of HEU—is at the heart of nuclear material security discourse. HEU is much easier to steal than nuclear weapons, and thus it is a greater target for terrorists seeking the means to a nuclear weapon.
- HEU can be used for purposes other than nuclear weapons. Many countries—such as the United States, the United Kingdom, Russia, and India use HEU to power their submarines. In the case of the US, HEU is also used to fuel aircraft carriers.
- HEU is not necessary for submarines. France uses LEU, and it is believed that China does as well.
- Though naval HEU is subject to stricter security than civilian HEU, the most prominent known theft of HEU was from a US naval fuel fabrication facility. Russian naval HEU was also the subject of theft after the collapse of the Soviet Union.
- Priority for securing HEU should be given to HEU stored at universities and research institutes, since they tend to be less secure than military facilities.
- Mid-2011: The global supply of HEU was ~1400 tons. That’s enough for more than 50,000 nuclear weapons (using the average of 25kg of HEU per warhead).
- Russia and the US hold the majority of this stock, thanks to the Cold War arms race legacy. 90 tons are distributed among other states with and without nuclear weapons.
- Less than 1% (enough for 400 warheads) is held by non-weapon states.
- Since the end of the Cold War, the Russian and US stockpiles of HEU have been reduced by ~600 tons. The process of reduction was through blending down HEU to 4-5% LEU. The LEU was then used for power reactor fuel. ~171 tons of additional HEU have been committed to this same process.
(Source: Frank von Hippel speech, “Global Nuclear-weapon Material Stocks and Risks,” at the 2012 Seoul Nuclear Security Symposium.