Two things. Deuterium stripping – if that is one of the operative gain mechanisms would still release lots of neutrons to be detected external to the reactor. Notice that the nickel cross-section for neutrons is basically rather low.
Secondly, however, the Mizuno reaction releases approximately two protons for every deuteron, not one as in stripping. That would imply that the neutron decays, instead of being absorbed in nickel or something similar which gives about twice the number of gas molecules as before. Also – there is a long half-life associated with nickel following neutron activation. This will be easy to characterize, for Mizuno - if that is what is happening. From: Eric Walker Jones Beene wrote: Since Yoshino did include slides showing the neutron cross-section of Ni58, the implication is that neutrons have been seen. I think the slides showing the neutron-cross section were hinting at the class of (X)Ni(d,p)(X+1)Ni reactions (which are generally exothermic), where a proton is expelled in a deuterium stripping reaction. If this is the correct interpretation, there would be no neutrons to detect. It would be the protons that would be detected, i.e., in an increase in molecular hydrogen correlated with a decrease in molecular deuterium. Note that the change in species does not appear to have been well correlated with excess heat, as the change was seen in both the trial and the control (as noted by Bob). Eric