How small? Dr. Swartz at MIT ran his NANOR for several months. He connected a small Stirling Cycle motor to it.
http://coldfusion3.com/blog/major-lenr-demonstrations-held
How small?
I don’t know. Small is not mega sized with all sorts of potential problems resulting from size.
A kid down the block had a job tending the reactor on a submarine. That is one version of small.
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