Watch: The Aukus agreement aims to create the most powerful attack submarine ever operated by the Senior Service
The training sees students undertake six months of intensive academic studies including subjects such as nuclear physics, thermodynamics and nuclear safety management.
That's followed by three months of practice where they learn the inner workings of nuclear systems and complete control room simulations to correctly respond to possible incidents and emergencies.
Lieutenant Joe Roberts said the course was one of the most intense in the Royal Navy, with many students dropping out.
"It's a course which demands the best and the brightest – and the Australians have sent them, three outstanding students who will go far," he explained.
"It's been something of an honour because these are the Aukus pioneers. They will go on to lead their country's future nuclear submarine programme."
Their success marks a significant milestone in developing the skilled workforce needed to operate Australia's future conventionally armed, nuclear-powered submarine capability being developed under the Aukus tri-lateral security partnership between the UK, Australia and the US.