The SI unit of intrinsic radioactivity in a material. One Bq indicates one disintegration per second and is thus the activity of a quantity of radioactive material which averages one decay per second. [..]

Used fuel assemblies removed from a reactor after several years use and treated as waste. Often it is another term for used fuel.

Depleted uranium (cf. enriched uranium)

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An element with atomic number of 89 (actinium) to 103. Usually applied to those above uranium – 93 up (also called transuranics). Actinides are radioactive and typically have long half-lives. They are [..]

A radioactive isotope of an element (e.g. in the steel of a reactor core) which has been created by neutron bombardment.

The number of disintegrations per unit time inside a radioactive source. Expressed in becquerels.

As Low As Reasonably Achievable, economic and social factors being taken into account. This is the optimisation principle of radiation protection.

A positively-charged particle emitted from the nucleus of an atom during radioactive decay. Alpha particles are helium nuclei, with 2 protons and 2 neutrons.

A particle of matter which cannot be broken up by chemical means. Atoms have a nucleus consisting of positively-charged protons and uncharged neutrons of almost the same mass. The positive charges on [..]