The money put aside to pay for decommissioning is actually a pretty minuscule part of the cost; that's all included under operating costs, which are lower than coal's, i.e. very cheap. A much bigger problem is the delay and uncertainty introduced by a chronically backlogged and red-tape-infested NRC. Think about it this way: building a modern giant nuke plant takes a lot of money, and every month you're waiting for approval is a month you're paying interest on that money. Interest on loans is a huge part of the construction costs of a nuclear plant, and one of the harder to predict.
