Someone explain to me what a fusion reactor is and how it's different from nuclear. Do they even exist or is this just all theory?
Fusion reactors generate electricity by fusing atoms, and conventional reactors use the heat of radioactive decay to heat a fluid.
Fusion reactors have been constructed in the past, but as of yet none have been build that can generate more electricity than is required to run the reactor (electromagnets, plasma heating, monitoring equipment, etc). Additionally, fusion reactors cannot meltdown; they require heated plasma which cools down to a harmless gas when there is a failure.