First, Nuclear is more than 10c/kWh unsubsidized at 90% capacity factor, which only gets worse as you try and scale up. France got into the 70% range and they had countries to export to. Nuclear is not even vaguely competitive even without energy storage involved. Just the fuel rod lifecycle alone costs almost as much per kWh as solar. 24/7/365 security is only the tip of the iceberg when you look into why Nuclear is so stupidly expensive. Maintenance for example takes up roughly 1 month per year of operation and you can’t send the guards home.
Anyway, it’s the same in that their all indirectly producing CO2. In a full accounting all of those things that make nuclear expensive actually produce CO2 because construction equipment, mining to produce the parts to build a reactor, etc etc all produce CO2 in the current economy.
In fact if you do the full breakdown for all activities related to Nuclear Reactor Construction, Operation, and Decommissioning their a very significant CO2 source in large part because all economic activity is and their really expensive. Regardless of how easy to draw arbitrary lines that ignore say CO2 emissions from workers daily commutes etc.
The only way to move past that is to have serious energy storage that’s used for all equipment and thus very widespread adoption of cheap battery technology. At which point Nuclear costs become an even larger issue because cheap batteries tank the cost of battery backed up wind/solar. In the end far northern countries can make some use of Nuclear, but it’s a dead end technology without a significant role in actually solving climate change.