Any nuclear Physical and or mental job where the first time you make a chemical composition mistake, it is probably going to spell some kind of imminent danger. Just think about how hard it is to find someone capable of doing the job, who is a decent human being to work with. But also keeping their world running smoothly without extra hassles to fatigue them.. And.. When you find out that finding this individual is harder to find than your patience can handle[be tested by] in pursuit of said person, then settling for the best option you think you already have in your sights.. And making that work out.