A crude terrorist nuclear bomb the size of a football detonating in the heart of a major city could have a devastating effect. It would release an equivalent of as much as 10,000 tons of conventional explosives. At the place of its detonation, the temperature would reach millions of centrigrade combined with an intense burst of gamma and neutron radiation which would be lethal for nearly everyone directly exposed within about a mile from the centre of the blast.
This is a low-probability, a non-existential risk on its own. However, if such an event happens at the same time as other catastrophic risks, such as pandemic or significant climate change events, it can become existential. Nuclear terrorism could include:
- Acquiring or fabricating a nuclear weapon
- Fabricating a dirty bomb
- Attacking a nuclear reactor, e.g., by disrupting critical inputs (e.g. water supply)
- Attacking or taking over a nuclear-armed submarine, plane, or base.
According to a 2011 report published by the Belfer Center for Science and International Affairs at Harvard University, can be executed and distinguished via four pathways:
Materials necessary for building a nuclear bomb today are stored at hundreds of sites in 28 countries, down from 52 countries in 1992 and over 40 countries just 10 years ago. But many of these sites aren’t well secured, leaving the materials vulnerable to theft or sale on the black market. Important commitments were undertaken to secure nuclear materials and improve cooperation during the 2010 and 2012 Nuclear Security Summits. Yet no global system is in place for tracking, accounting for, managing and securing all weapons-usable nuclear materials. This poses a real risk that such nuclear materials may be used for creating a fully functioning nuclear bomb or so called ‘a dirty nuclear bomb’.