Plans by the Coalition to build large nuclear reactors on the sites of old coal-fired power stations would be prohibitively expensive, take more than a decade to implement, and would not work in most cases because such reactors need to be near water, Prime Minister Anthony Albanese said.

Mr Albanese, who as shadow environment minister two decades ago fought plans by John Howard to consider nuclear power plants near populated coastal communities, said little had changed in terms of the political difficulties of such a proposal.