All right, you're going to have to really humor me here. As far as I know, the only kind of 'cold' fusion that has ever been demonstrated to work is muon-catalyzed. The reason it isn't viable is that is takes so much energy in the first place to create muons and they have a very short half-life. There is, however, a neverending supply of free muons continually being produced in the upper atmosphere above the ozone layer by cosmic rays interacting with the atmospheric gases. If (I know it isn't possible, but this is where you have to humor me) we could float a reactor platform in low orbit just above the ozone layer, what kind of yield would such a reactor give? If I'm wrong about anything I said above, please correct me. My knowledge of this subject is limited to what I learned just reading through books for fun over ten years ago. It's out of date and I've forgotten most of it besides. I'm considering using an orbiting reactor platform like this in a science fiction story, and I just have to know if it's even theoretically possible.