Australia is looking towards Sweden to help prop up its ageing Collins class electric-diesel submarines.
The submarines will undergo work to extend their operating life in 2026 as Australia looks to bridge a capability gap before the first nuclear sub arrives in the late 2030s at the earliest.
Navy chief Mark Hammond said defence is working to take the associated risks out of the complex process to extend the subs' life by engaging Swedish counterparts.
"I am learning from their life-of-type extension they've gained from their Gotland submarines," the vice admiral told a Senate estimates hearing.
"This is one of my highest priorities."
Representatives from Swedish defence company Saab AB were hosted in Australia in the past six weeks.
The Collins class have also suffered from availability delays in the past year due to COVID-19, and the prioritisation of other navy vessel repairs.
Vice Admiral Hammond said the delays should be cleared within the next 12 months.
"But the submarine availability overall in my last role as fleet commander has been exceptional," he noted.
One of the defence department's top submarine officials said the decommissioned boats could then be used as backups if supply chains fail and run alongside their nuclear counterparts.
"In some regards, the existence of the nuclear powered ambition helps to de-risk Collins' life extension," John Chandler told a Submarine Institute conference.
Defence brass said no infrastructure decisions related to the nuclear-powered submarines had been made.
More than 430 people form part of the nuclear submarine taskforce, spanning the departments of defence, foreign affairs, prime minister and cabinet, attorney-general and education.
Further costs to the cancellation of the French Attack class submarine contract have also been revealed.
The total costs of the cancellation has been put at $3.4 billion, including a $830 million contract breaking fee to the French Naval Group.
But the government has also set aside more than $290 million to retrain people who lost their jobs when the contract was cancelled.
Officials noted the figure is a "do not exceed" number, not an exact cost.
Defence bureaucrats said the cost for the 219 jobs over three years didn't solely include salaries, but training, postgraduate education in nuclear science and activities that support future growth.
Officials said the money wasn't a further sunk cost from the French contract with the retraining going towards Australia's ability to operate nuclear propelled submarines when they arrive.
A further $300 million writedown of a $470 million naval yard by Australian Naval Infrastructure also wasn't included in the public total, given it was off defence department books.
But some of the facilities can be repurposed for Australia's nuclear submarine program.