B. Annex B: radiological protection quantities in the context of prolonged exposures

(B1) The principal physical quantities used by the Commission are the activity of an amount of radionuclide and the absorbed dose from radiation in matter. The absorbed dose is weighted for radiological protection purposes, resulting in a number of relevant dosimetric quantities. (B2) Activity: The activity, A, of an amount of a radionuclide is de®ned as (ICRP 1991a, paragraph 37): `The average number of spontaneous nuclear transformations taking place per unit time. Its unit is the reciprocal second, sÿ1, given, for this purpose, the special name becquerel (Bq).'