Not really. Certainly some “encryption” algorithms or really implementations have backdoors, but RSA for example doesn’t. Encryption is only worthwhile if it’s mathematically sound, and you can’t backdoor mathematics without some random undergrad working on their maths degree figuring out for fun.
The material will run out after a few billion billion billion terawatts have been generated, assuming with use both uranium and thorium. It’s like saying is solar free if the sun is going to run out?
Incidentally,
All solar power is nuclear power, and if you’re brave enough all nuclear power can be solar power.