Which of the following are true? Choose all that apply.
A. Nuclear fusion has never been achieved by scientists and engineers.
B. Fission nuclear reactors and weaponry rely on uranium-235 and plutonium-239, both of which are fissile, however, they are usually present in a much larger background of non-fissile uranium-238. Fission nuclear weaponry requires significantly higher purification of these fissile isotopes.
C. A hydrogen bomb with the same explosive power as a purely-fission bomb produces much less long-lived radioactive fallout.
D. Waste from nuclear fission remains significantly radioactive for thousands of years; waste from a fusion nuclear reactor would not present a significant hazard.
E. Plasma is a '4th state of matter' which consists of a gas-like state with such high temperatures that electrons do not remain bound to individual atoms, such that it is a 'cloud' of charged particles.
F. The primary development issue with nuclear fusion is containment of high-energy plasma; stars can easily contain the plasma and sustain nuclear fusion with electromagnetic fields, but here on earth, so far we are limited to using gravity.