Prime Minister Anthony Albanese has arrived in the United States before he is expected to announce key details of Australia’s acquisition of nuclear-powered submarines under the AUKUS security pact.

Mr Albanese will join US President Joe Biden and UK Prime Minister Rishi Sunak in San Diego for the announcement on Tuesday, Australian time.

No details of a deal have been announced but reports suggest the “pathway” to nuclear-powered submarines will unroll over three stages and two decades.

The timing has been designed to minimise the gap in national defences of a changeover to nuclear propulsion when Australia’s existing fleet of six diesel submarines come out of service in the middle of next decade.

The shift will likely begin with the deployment of American submarines by 2027, the Wall Street Journal reported, likely in Perth and then Port Kembla in New South Wales.

Australia would then acquire up to five Virginia-class submarines which would begin operating from 2032 while construction of a modified British-designed submarine continued through the next decade.

How and where they are constructed has not been confirmed.

South Australian Premier Peter Malinauskas said he expected at least some of the submarines to be built in Adelaide.

Whether Australia would have to finance production in North America is another open question.

The deployment of American submarines from 2027 will begin the long process of training nuclear-qualified crew and commanders in Australia.

On Sunday Democrat congressman and chair of the AUKUS caucus Joe Courtney said concerns over joint crewing of submarines had been “over-hyped” and once handed over submarines would be “under Australian control”.

“Everyone understands we need to train up the Australian sailors and officers in terms of nuclear propulsion,” he said.

“It’s going to be a transformational enterprise for working people in Australia.”

Asked if Australia would get second-hand submarines or new ones, Mr Courtney reassured that the country would get the “highest quality”.

“No one’s gonna be foisting off clunkers to good friends and allies,” he said.

One independent estimate of the cost of acquiring eight submarines comes in at $125 billion over 30 years.

The government would need to “make some difficult decisions”, Mr Albanese said, prompting questions about the budget.

“We need to ensure that Australia’s defence assets are the best they can be,” he said.

The trilateral alliance was announced in 2021 as a counter to rising Chinese power, but details of how it would take shape have been the subject of negotiations over the past 18 months.

Port Kembla has reportedly emerged as the favoured site for an east coast base for the submarines because of its deep ocean approaches, the ABC reported.

It will be the fifth time Mr Albanese has met President Biden and his second meeting with Mr Sunak.

Thousands of Australian workers to benefit

Australia’s plan to acquire nuclear-powered submarines will create and support about 20,000 jobs over the next three decades.

The government is expected to announce this plan will boost thousands of jobs across the nation’s industry, defence force, and public service.

At its height, up to 8500 Australian jobs will be supported to build and maintain the boats, and will include highly-skilled scientists, engineers, project managers, and other trades workers.

Thousands of skilled workers will be needed to support growing supply chains, shipyards and technical bases in all three countries.

Speaking from India on Saturday, Mr Albanese said Adelaide and Western Australia were set to benefit from the creation of jobs and manufacturing opportunities.