Nuclear agents are derived from neutron radiation (n) which is a neutron emitted by an unstable nucleus, in particular during atomic fission and nuclear fusion. Apart from a component in cosmic rays, neutrons are usually produced artificially. Because they are electrically neutral particles, neutrons can be very penetrating and when they interact with matter or tissue, they cause the emission of beta- and gamma-radiation. Neutron radiation therefore requires heavy shielding to reduce exposure (IAEA, 2004).

Explosive agents include improvised explosive devices (IEDs) which can be made anywhere from a wide range of materials – from everyday tools, to conventional explosives, to commercial explosives used in construction and mining. They are cheap and relatively easy to construct (UNODA, 2014).

A substance or a material emitting, or related to the emission of, ionizing radiation (either in the form of electro-magnetic waves or particle radiation) is radioactive. Depending on the magnitude of exposure, the radioactive substance may become a hazard to human health; as such it is subject to regulatory control by national laws and national regulatory authorities. Radioactive material may also be hazard to animal health, other forms of life and the environment (IAEA, 2018).