re: There is no need to debate, all you need is---
To answer the following 3 questions.
1) Can atmospheric molecules escape the Earth's gravitational influence?
Note #1: Before answering the above question please read the information on the NASA site: http://science.nasa.gov/newhome/headlines/ast08dec98_1.htm
Note #2: The quantity is not in question here, so a Yes or a No answer will do.
2) Are there radioactive atoms suspended in the Earth's atmosphere? (yes or no)
3) Do radioactive atoms impart kinetic energy to their surroundings? (yes or no)
Once you have answered these questions, then we can "debate" about the quantity of radioactive elements in the atmosphere and how they get there.