It also uses a more modern technology that doesn't need highly enriched uranium.
The K15 is a brand new untried reactor - designed specifically to fit inside the Barracuda class. So inherently there is risk.
It also needs refuelling every 5-10 years as it s uses similar fuel to land based French PWR. Not a problem for the French with the entire infrastructure and production and storage chain - but a complex problem for Australia relying on the support French over the life of the boat.
https://tinyurl.com/ue6zbzw3
https://www.navalnews.com/naval-news...-ssk-variants/