The graph on the global studies page does seem to indicate that. However, if you actually read the data and how the graph was prepared, it uses one dataset for renewables and a different dataset for nuclear and coal. Additionally, these numbers significanly differ from the IEA data which shows that nuclear is one of the least expensive. As I said in a comment below, there are other, more localized studies that show nuclear is one of the cheaper ways to produce electricity. I would hesitate to say that nuclear is the cheapest option since there are different studies with different results, but to claim that it is the most expensive would be just as misguided for the same reasons. At the end of the day, more electricity is needed as countries look to decarbonize there energy needs. Hydro, wind, and solar are effective and renewable but a stable, carbon-free solution is needed where there is insufficient hydro or geothermal and I believe nuclear fits that bill perfectly.