Eros sure sounds like he is producing muons and I know that Russ will use a cloud chamber. Excess heat is hard to detect but muons are easy.
I reply here as it is more in-topic to this thread.
I would like to remind that one thing is cosmic muons (~4 GeV at sea level), another is 10-20 MeV muons supposedly generated in systems similar to those of Holmlid, at least at his power levels. How would a standard cloud chamber behave in this case?
To be more clear: to see something in this case it could turn out to be necessary to quickly put fresh reactor "ash" inside the chamber like Piantelli reports doing, without the guarantee that this will work.