Discovery could keep nuclear subs in deep

Australia's upcoming fleet of nuclear submarines could stay underwater and undetected for longer with the help of a ground-breaking discovery.

A study helmed by Melbourne-based nuclear materials expert Michael Preuss has identified a key factor behind how quickly nuclear fuel cladding material corrodes.

The cladding material is an "alloy", which is a metal with a few additional elements, Professor Preuss said.

It encapsulates a submarine's nuclear fuel, creating a barrier between it and the surrounding water.

"Metals essentially have small crystals and those crystals are orientated in all sorts of different ways," he told AAP.

"What we found is that this orientation of the crystal in the metal locally affects how fast the oxide grows or not.

"(Because) through the processing (of cladding) you can influence the orientation of those metal crystals, you can therefore influence the rate at which the material corrodes."

Nuclear-propelled submarines could run for 25 years without refuelling but it was important to be able to predict the cladding's life span to ensure their longevity, Prof Preuss said.

The research discovery meant engineers could look at the cladding and figure out how quickly it would corrode with more confidence, or process the material in a way that made it last longer.

It has previously been difficult to accurately predict cladding's life span.

Prof Preuss joined Monash University's engineering faculty in 2020.

"There will most likely be cracks in the wings of (an) aeroplane and those wings are getting monitored," he said.

"When the crack reaches a certain length in the material, then it becomes a problem and then they repair it.

"But they know how fast the crack grows, and they know when they have to do something about it - and it's the same here."

Australia is slated to reveal what type of nuclear submarines it will acquire in March after AUKUS - the trilateral security pact between Australia, the United Kingdom and the United States - was announced in September 2021.

The country has previously only operated diesel submarines, which require regular refuelling, and needs to develop a skill base in nuclear engineering to maintain and eventually build nuclear submarines, Prof Preuss said.

Monash has been commissioned to develop a report on the skill base required in the nuclear materials field, with the university to consult academics, industry and organisations from Australia and overseas.

The new study was published in Nature Communications.