Thinking over the series of Japan-US two-phase flow seminars, the necessity and meanings of the multi-phase flow research are mentioned over the research conducted concerning the accident at Fukushima Daiichi Nuclear Power Station. There could be found the heavy concerns on the difficulty of elucidating the complex phenomena at the accident; none-the-less, there surely exist not a few places in which the multiphase flow research could play the important and active roles, repeatedly conducting and accumulating research on the steady road to fulfill the elucidation of the accident and recover the trust, after the fact of which I would believe that we could draw a future image of new nuclear powers.