The Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (National Institute of Ionizing Radiation Metrology)—ENEA-INMRI—is responsible for developing and providing the Italian national standards relating to the ionizing radiation quantities. ENEA-INMRI belongs to ENEA and is located at the ENEA Casaccia Research Centre, near Rome.

The National Calibration System in Italy, as established in 1991 by the Act No. 273, was originally based on three national metrological institutes: IEN, IMGC-CNR and ENEA-INMRI. In 2006 IMGC and IEN merged into one institute which was called INRIM. Each of these primary standards institutes has the task of maintaining the national standards relating to a specified group of physical quantities and units.

ENEA-INMRI is one of the Italian signatories of the “Mutual Recognition of National Measurement Standards and of Calibration Certificates Issued by National Metrology Institutes” (MRA), the international arrangement describing the fundamental conditions of this mutual recognition.