A global threat for millennia: experts warn Australia’s nuclear submarine legacy will be weapons-usable uranium cache

Ben Doherty,25 June 26, https://www.theguardian.com/world/2026/jul/25/aukus-nuclear-submarines-danger-weapons-grade-uranium

Uranium waste from Aukus submarines will be enriched to an estimated 80%: the same level as the bomb dropped on Hiroshima.

Australia’s proposed nuclear submarine fleet will leave behind tonnes of weapons-usable uranium-235: radioactive for hundreds of millions of years, and capable of being processed into scores of warheads, nuclear experts have told a public inquiry into Aukus.

And a former White House national security adviser has told the Guardian that Australia’s Aukus deal – involving the transfer of highly enriched uranium to a non-nuclear weapons nation – sets a dangerous proliferation precedent that other countries such as Iran could try to exploit, weakening global control of the spread of weapons-usable nuclear material.

Associate Prof Tilman Ruff, founding chair of the Nobel prize-winning International Campaign to Abolish Nuclear Weapons, told the Aukus public inquiry that the legacy of Australia’s nuclear submarine fleet – of which each vessel will have a service life of about three decades – will be hundreds of kilograms of high-level radioactive waste. Even as waste, the submarines’ spent reactor fuel will be highly enriched uranium (HEU), usable to build nuclear weapons.

“No nation has resolved the huge problem of how to manage this material and there’s no guarantee – given the timeframes involved and the hazards of the material over geological time – that any arrangement that we come up with could reliably isolate that material for hundreds of thousands, or millions of years.

“The additional complication here is that it needs a really high level of security because, in 10,000 years, somebody could still go and dig that stuff up and build nuclear weapons with it.”

The uranium left behind by Australia’s nuclear submarines at the end of their working lives will likely still be enriched to about 80%: the same level as the atomic bomb dropped on Hiroshima.

The Australian government has repeatedly said the precise amount of high-level nuclear waste that will be left behind by its submarine fleet is classified.

But documents released under freedom of information laws show Australia will be responsible for each submarine’s nuclear reactor compartment, “roughly the size of a four-wheel drive”, and spent nuclear fuel “roughly the size of a small hatchback”.

Leading global experts on non-proliferation have now estimated each nuclear submarine decommissioned by Australia – beginning in the 2050s – will contain about 400kg of HEU, enriched to about 80%, containing about 320kg of uranium-235 (U-235).

The International Atomic Energy Agency states a “significant quantity” of highly enriched uranium – enough to make a weapon – is 25kg of contained U-235.

U-235 has a half-life of 700m years: it will be a weapons proliferation risk for millennia. And the radioactive materials generated by its fission process will be toxic to humanity and the environment for millions of years.

The HEU left behind by each one of Australia’s three second-hand Virginia-class submarines bought from the US would be sufficient for more than a dozen weapons.

Australia’s domestically built Aukus-class submarines – Australia is proposing to build five – will be powered by Rolls-Royce’s in-development PWR3+ reactor. The quantity of HEU required to power that reactor is classified but they are expected to be larger than the Virginia-class reactors, Ruff said.

The Aukus agreement mandates that Australia is responsible for the disposal and storage of all of the nuclear waste left behind by its nuclear-powered submarines in perpetuity

By the end of the century, when all eight of Australia’s planned nuclear powered submarines have been retired, Australia will be responsible for the management of “at least 3 tonnes” of U-235 in the highly enriched uranium spent fuel waste, Ruff told the Guardian.

“That’s enough for 120 nuclear weapons using the International Atomic Energy Agency standard.”

Australia has spent decades reducing its HEU stocks. There is presently less than 3kg of HEU in the entire country, held for research purposes.

Ruff told the public inquiry into Aukus, established by the Australian Peace and Security Forum, that his primary concern over Aukus was that it exacerbated regional tensions and made Australia “a higher priority target, including for nuclear attack”.

Ruff cited the work of Dr Frank von Hippel, senior research physicist and professor of public and international affairs emeritus at Princeton University, who estimated that the reactor of a Virginia-class submarine – such as those Australia is set to buy from the US – would be decommissioned at the end of its working life still containing about 400kg of HEU, enriched to about 80%.

Von Hippel, who served as an assistant director for national security in the Clinton White House, told the Guardian “by the IAEA’s metric, 0.4 tons of 80% enriched uranium would be sufficient for 13 implosion bombs”.skip past newsletter promotion