We have investigated the process ${\ensuremath{\nu}}_{H}$e\ensuremath{\rightarrow}${\ensuremath{\nu}}_{L}$e in which heavy neutrinos interact with electrons and convert to massless neutrinos. In principle the process could be used to investigate primordial nonzero-mass neutrinos. However, the cross section is too low for the process to be useful with the currently available experimental techniques.