Prime Minister Anthony Albanese earlier this month revealed the $368 billion pathway Australia will take to get the boats under a security pact with the US and UK.
ACTU president Michele O'Neil said unions were seeking more detail from the government so they could discuss what this meant for workers in worried communities.
"The ACTU has a long-standing policy of opposition to nuclear power, nuclear waste and proliferation," she told the National Press Club in Canberra on Tuesday.Â
"We also have a long-standing policy position that supports a nuclear-free defence policy."
Under the nuclear submarine program, US and UK boats will start rotating through Western Australia from as early as 2027.
Ms O'Neil said there had not been the chance to talk through the acquisition of nuclear-powered submarines due to a lack of information.
"There are safety issues for us," she said.
"These are things we're going to have to work through because it's not at all clear what the answers to those are yet."
Ms O'Neil said with the high price tag accompanying the boats, she expected this to deliver "good quality jobs" for Australian workers.
The criticism from the union movement follows stinging remarks made by former Labor prime minister Paul Keating, and concern over the plan voiced by some of the government's MPs.
