State of art the quantities, units and standards in the field of ionizing radiations

After a short presentation of the quantities and units involved in ionizing radiation measurements, this paper describes the present situation of references and standards in France, for radioactivity metrology, neutron metrology and dosimetry. These references imply the definition and use of various means: special radioactive sources, radiation beams, and high quality methods and technics of measurements. These means are completed by metrological co-ordination operations, at a national level (calibration chain, interlaboratory tests), as well as at an international level (intercomparisons between national standards laboratories)