What about a more visual description, like "safety circle"? When I was a Boy Scout learning to use an axe, they called the danger zone within reach of the axe

What about a more visual description, like "safety circle"? When I was a Boy Scout learning to use an axe, they called the danger zone within reach of the axe the "blood circle". A bit overwrought, but it certainly stuck in my mind. I think they say "safety circle" now.