It is a popular misconception that nuclear fusion
power is free of radioactivity; in fact, the deuterium-
tritium reaction that nuclear scientists are currently
exploring with such zeal produces both alpha particles
and neutrons. (The neutrons are used to produce tritium
from a lithium blanket surrounding the reactor.)
Another common misconception is that nuclear fusion
power is a virtually unlimited source of energy because
of the enormous quantity of deuterium in the sea.
Actually, its limits are set by the amount of available
lithium, which is about as plentiful as uranium in the
Earth's crust. Research should certainly continue on
controlled nuclear fusion, but no energy program
should be premised on its existence until it has proven
practical.