The only reason it takes "years" is due to the obstructionist regulations and constant delaying lawsuits engendered by the anti-nuke "green" nutcases.
"What I don't understand is why no serious effort has been undertaken to develop the technology to control the nuclear fusion reaction for use in power generation."
Hundreds of billions of dollars have been spent on fusion research, with no useful results to speak of. It turns out to be REALLY HARD to do fusion on a scale smaller than a star. We will have practical, cheap solar cells and hydrogen power before workable fusion reactors are realized. Two pieces of desert southwest 100 x 100 miles will supply the ENTIRE energy requirement of the US (gas, oil, coal, AND electric).