Radioactive Warning Symbol - International Ionizing Radiation Hazard Sign #131663 (License: Personal Use)

This iconic symbol, known as the trefoil, consists of three black blades arranged radially around a central circle on a bright yellow background, enclosed by a black circular border. It was developed in 1946 at the University of California, Berkeley, and standardized by ISO 361 and IAEA regulations for use on containers, equipment, and facilities handling radioactive materials. The high-contrast design ensures visibility and immediate recognition to prevent accidental exposure.

Used on signage for nuclear facilities, medical radiology departments, radioactive waste containers, and transport labels; matches user intent for safety education, regulatory compliance, or hazard identification resources.