"CSIRO has come up with an estimated construction cost for a...

"CSIRO has come up with an estimated construction cost for a 1000 MW nuclear plant of at least $A8.6 billion," - So Australia could replace its current fleet of 21 GW of coal-fired power generators fir under $200 billion, and that fleet is currently providing around 60% to 70% of energy to the NEM. Don't confuse generation capacity with energy delivered. You have to apply the capacity factor.

The estimated LCOE figures of $163/MWh-$264/MWh. I'm pretty sure these are the figures that have been challenged by the Centre for Independent Studies (CIS) because they assume a nuclear power plant has a life of only 30 years (more likely 60 to 80 years) and a capacity factor of a bit over 50% when baseload plants in Australia typically have a load factor of around 75%, which could increase with overnight EV charging and use of pumped hydro systems currently being built.

"Australia would need to exceed the highest nuclear build rates ever achieved." - Hardly. France had a much more rapid build out of its nuclear fleet in the 70's and 80's.

In summary, I think the text you appear to have lifted from somewhere is misleading.