If by "Chernobyl" you mean any nuclear accident that results in some kind of radiation release, then of course, it is a possibility as long as we build any kind of nuclear reactor. But if by "Chernobyl" we mean a massive explosion of an uncontained reactor that contaminates thousand of square kilomoters of land severely, and spreads some degree of contamination across continental areas, then it's an entirely different story. It is possible to build reactors that simply don't have a catastrophic failure mode like the Soviet RBMK, or evenm like those of 1950s and 1960s designs for BWR (used at Fukushima) or PWR (Three Mile Island). Any design can fail, of course, but how they fail, matters.