The categorization system is based on the concept of ‘dangerous sources’, defined as sources that could cause severe deterministic health effects.
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Radiation sources are classified into five categories based on IAEA Safety Guide RS-G-1.9 standards, arranged according to the level of potential harm they may pose if not properly controlled. This system helps regulators, operators, and safety professionals apply appropriate security, licensing, and emergency preparedness measures.
Extremely dangerous to the person. This source, if not safely managed, would likely cause permanent injury or death within minutes to an hour of exposure.
High-level security, frequent inspections, and robust emergency response plans are mandatory for these sources.
Very dangerous to the person. Could cause permanent injury within minutes to hours. Could be fatal if close to unshielded material for hours to days.
High-level security, frequent inspections, and robust emergency response plans are mandatory for these sources.
Dangerous to the person. Could cause permanent injury within hours. Unlikely but possibly fatal if exposure lasts days to weeks.
Standard safety protocols and regular equipment calibration are required.
Unlikely to be dangerous. Permanent injury is very unlikely, though temporary injury could occur from many hours of direct contact.
Standard safety protocols and regular equipment calibration are required.
Most unlikely to be dangerous. No one could be permanently injured by this source, though delayed health effects are theoretically possible.
Standard safety protocols and regular equipment calibration are required.
These categories are for planning and regulatory guidance. For specific D-values and activity-based calculations, please refer to the IAEA Technical Document 1344.
