High energy astrophysics.
I'm on the fence on this, leaning slightly in favor of the genuineness of the phenomenon: I attribute the irregular results to any transmutation taking place being devilishly sensitive to the presence, absence, or prevalence of certain stuctural features of the Ni powder. Think of preparation of surfaces for electrochemistry or for catalysis; think of trying to predict (ab initio) the *exact* way a car's hood will crumple during a car wreck.
If the phenomenon is real, the paucity of signal might be a catch-22: operating in the dark, it's hard to know how to prepare the system to maximize transmutation: and without reliable transmutation, it's hard to get enough data to come up with a detailed model.
Time will tell, as they've promised a scale-up in the October time frame.
Cheers!