Environmental parties in Australia (The Greens and similar) were built on the idea of resisting nuclear and hydroelectric, so you have decades of lobbying against it. Eventually the coal lobbies allied with the more conservative parties as The Greens started pushing for wind/solar. This made sense for the conservative parties as Australia produces nothing of value outside of iron ore and coal.

There is no mainstream party that supports nuclear outside of the libertarian party (which gets single digit percentages at the ballots).