Learn about the Stefan-Boltzman law and thermal equilibrium
A lightbulb has a constant supply of energy (when it is switched on)
Let's say 100 W - 100 J/second
This energy is dumped into a tiny tungsten filament weighing a gramme or less. The filament gets very hot, very quickly.
But then, it STOPS getting hotter. Why? Because it radiates away its excess energy as photons of thermal IR and visible light.
In the same way, any radiation released in the upper crust or lower atmosphere of the earth by nuclear processes (or by burning carbon-based fuels, or by sunlight), is simply radiated away to the atmosphere and space from a marginally warmer surface or lower atmosphere.
Even high-energy cosmic rays are essentially thermalised within the atmosphere itself.