Radioactive Warning Symbol - Meaning, History, and Safety Use #1207152 (License: Personal Use)

This internationally recognized radiation hazard symbol, known as the trefoil, consists of a central black circle with three black blades spaced at 120-degree intervals on a yellow field, enclosed by a black border. Designed in 1946 at the University of California, Berkeley, it was standardized by ISO 361 and adopted globally for labeling radioactive materials, equipment, and controlled areas. Its high-contrast color scheme ensures visibility and immediate recognition for safety compliance.

Used on signage, containers, lab equipment, and nuclear facilities to warn personnel and the public of radiation risks; matches user intent for safety education, regulatory compliance, or emergency response training.