To follow on from that. and from the comments I have seen concerning the decision..,
The French haven’t yet finished commissioning their first new SSN for 30 years (the Suffren), which is only displaces 5K tons compared to the Astute class at 7.5K, and hence can carry only a total of 18 torpedo/Mx (French models only). Not a lot of firepower if you have to cross an ocean to rearm.
Not sure if the size is a result of reactor output, but it has also led to far more automation with a crew of only 65, even at that complement it can only carry enough food and other consumable for a maximum of 70 days as opposed to around 90 for the Astute. With comments raised about rotation in combat and fatigue on long patrols. Again something not optimum for Pacific oceanic distances.
In short, once deciding to go nuclear, there would have been a lot of risk in Oz opting for a French boat built for for Med and Atlantic littoral Ops for the Pacific theatre.
One thing I discovered when researching Astute vs Virginia class subs, which surprised me was the following.
”The US Virginia-class SSN has a S9G reactor of about 150 MW driving a 30 MW pump-jet propulsion system built by BAE Systems (originally for the Royal Navy).”
https://www.navaltoday.com/2014/02/2...opulsors-deal/
p.s. The Virginia class S9G reactor doesn’t need refuelling for it’s planned lifetime, as with the PWR2 in the Swiftsure and Astute subs - but again it would then depend on Congress approving export of nuclear material.