Thank you Tom for your intelligent answer, it gives me a clear understanding of what your objection is to my CONJECTURE, and question.

Obviously you and many others here believe that the 'radioactivity' which has been released into the atmosphere has no effect, heating or otherwise, on the upper reaches of the Earth's atmosphere.

My point is that your 'assurance' may or may not be valid.

Same as my 'assurance' that I can place another drop or two of water into an already full glass.
I may or may not succeed, it will depend on how 'full' the glass is already. It will be of no value for me or anyone else to 'calculate' the volume of the water drop and 'calculate' the volume of water in the glass and compare those two volumes with each other. Without knowing the volume of water that the glass can hold, the numbers are useless.

Similarly, the amount of energy from the Sun and the energy from the radioactivity can be compared, and indeed is valuable and interesting, but without knowing how much 'energy' the 'Earth's atmospheric system' can hold safely, or how that extra 'drop' of energy will affect the total, the numbers are meaningless in resolving the question.

Cheers
Johannes