According to CND, who originated the Peace Symbol, it is a superposition
of the international semaphore code positions for N (nuclear) and D (disarmament),
inscribed in a circle:
N D
O
o |o
/+\ \+\
O | O ||
/ \ / O
Well, that's the best I can draw them. The D is supposed to be straight up and down
for the most part, but I'm sure you get the point.