The new French Barracuda is the only nuclear submarine design that might be available to Australia in the future, but without a nuclear industry here they would need to travel back to France about every 9 years of their life to have their "civilian" grade nuclear fuel replaced. I wouldn't like to rely on the French for this.
American and British nuclear subs, with their weapons grade uranium fuel, are simply not for sale - not even to Australia.
Nuclear subs certainly have greater range and speed but are generally noisier than diesel subs and more easily detected in shallow waters, like the Yellow Sea, due to the heat signature of their reactor.
