HOW NUCLEAR SUBMARINES WORK
Nuclear submarines are powered by on-board nuclear reactors. Atoms in the reactor split, releasing energy as heat.
The heat is used to create high-pressured steam, which turns a set of turbines providing power to rotate the boat’s propeller. Additional turbines create electricity for the rest of the submarine. Steam from the reactor cools down to condense back into water, which is directed back through the system and the process starts again. It’s often described as a “big, fancy tea kettle”.
The nuclear reactor contains highly enriched uranium, however the system is carefully shielded to protect the crew from radiation. Research shows US Navy officers on board nuclear submarines are exposed to only 1.7 mSv of radiation per year.
Highly trained reactor engineers work in shifts to limit exposure and wear radiation monitors that are checked regularly.
Australia will acquire a new fleet of at least eight nuclear-powered submarines, with many or all of the boats to be built at the Osborne shipyard in Adelaide. The first of the boats are expected to be ready by 2040.
Either the US or the UK will provide Australia with pre-assembled nuclear reactors to be fitted on the boats, significantly limiting any potential for exposure to ionising radiation.
The only limit on a nuclear submarine’s time at sea is the food supply for crews. The submarines will be commissioned with enough uranium fuel to last 30 years.
The considerable endurance and range of nuclear submarines provide an unparalleled tactical advantage, and is the biggest difference from diesel-electric submarines like the Collins-class.
In the US, once nuclear reactors are decommissioned, the radioactive parts are shipped to a disposal site on barges under the control of the Department of Defense following stringent safety protocols and regular waste monitoring.
Australia has a long history of nuclear safety and stewardship, as the Australian Nuclear Science and Technology Organisation enters its 70th year.
ENGINE ROOM
benefit at some point in their life.
The reactor is used to produce many radioisotopes including Phosphorus-31 for the treatment of excess red blood cells and Technetium-99m used for medical imaging.
Less widely known is that ANSTO’s reactor also produces 50 per cent of the world’s irradiated silicon, used in a range of advanced systems such as power grid infrastructure, wind turbine systems and high-speed trains.
On top of its commercial duties, the 1300-strong ANSTO is a leader in cuttingedge research programs, and each year opens its doors to 5000 researchers from around the world, visiting Lucas Heights and the Australian Synchrotron in Melbourne.
ANSTO is also responsible for providing trusted advice to the federal government on nuclear technology, including the nuclear-powered submarines to be built under the AUKUS pact with Britain and the US.
Dr Apperley is aware of the considerable challenges with developing a nuclear skilled workforce capable of operating submarines fuelled with highly enriched uranium – an objective he labelled “the biggest pole in the tent”.
“The nuclear piece is really new and it will be complex and it will be hard – but the rest of the submarine is conventional, in the sense that it is a war-fighting machine and Australia has significant experience in this,” he said.
“The new bit is it’s going to have a propulsion system, the energy for which comes from a nuclear reactor, and the submarine taskforce will probably be the first group to say ‘yep, standing up suitably qualified and experienced nuclear personnel is job number one.”
But Dr Apprley said Australia had a headstart that should not be underestimated.
“Our nuclear baseline is very solid. ANSTO and Australia operates a very complex and sophisticated nuclear operation,” he said. “We know that when the US and UK visited ANSTO in early 2022, it provided significant confidence that Australia had a foundation – it had a baseline on which it could build.”
Despite a pledge to arm the submarines with conventional weapons, the AUKUS pact has attracted considerable scrutiny from antinuclear groups concerned about domestic safety and Australia becoming a target for global adversaries.
In August, SA Greens senator Barbara Pocock attended a rally in Adelaide that made baseless claims the AUKUS submarine deal would lead to another Hiroshima-style atomic bombing that killed 140,000 people in 1945. Defence SA boss Richard Price said growing international instability meant acquiring nuclear-powered submarines was crucial.
“People don’t understand nuclear – they just hear the one word ‘nuclear’ and immediately jump to the conclusion that we’re talking about large scale nuclear energy plants such as Chernobyl (which exploded in 1986),” Mr Price said.
“Technology has moved a long way in the nuclear energy industry, but what we are talking about is a much smaller reacter on a submarine … so it’s nowhere near the same issue as you’re dealing with in a power station.” Mr Price said nuclear-powered submarines were the “ultimate stealthy platform” that could travel thousands of kilometres away in a short period of time and stay submerged indefinitely.
“It puts incredible uncertainty in other people’s mind as to where they are, and if they have to go hunting for submarines, it ties up a tremendous amount of resources,” he said.
“They can stay operational for so much longer, they also travel much faster and they don’t have to resurface to recharge batteries, so they are so much harder to find than a conventional submarine over a long period of time.”