includes a range of elements and activities, including: legislation and regulation; intelligence gathering; assessment of the threat to radioactive material and associated locations and facilities; administrative systems; various technical hardware systems; response capabilities and mitigation activities. No single government or industry organization or subsection of such an organization can address these elements in isolation (Source:  IAEA Nuclear Security Series, No.7). 

Guidance on nuclear security regime can be found in IAEA Nuclear Security Series No. 20: Objective and Essential Elements of a State's Nuclear Security Regime.  This document defines the nuclear security regime as follows:

"A regime comprising:

• The legislative and regulatory framework and administrative systems and measures governing the nuclear security of nuclear material, other radioactive material, associated facilities and associated activities;
• The institutions and organizations within the State responsible for ensuring the implementation of the legislative and regulatory framework and administrative systems of nuclear security;
• Nuclear security systems and nuclear security measures for the prevention of, detection of and response to nuclear security events."