Radioactive Warning Symbol - International Ionizing Radiation Sign #228695 (License: Personal Use)

This iconic symbol, known as the trefoil, consists of a central black circle with three equally spaced black blades radiating outward on a bright yellow background, enclosed by a black border. Designed in 1946 at the University of California, Berkeley, it has since become the standardized warning for ionizing radiation worldwide. Its high-contrast design ensures immediate recognition and conveys urgent caution in nuclear, medical, industrial, and research settings.

Used on signage, equipment, containers, and documentation to indicate the presence of radioactive materials or radiation-emitting devices; matches user intent for safety information, regulatory compliance, educational content, or hazard identification.