Japan was set to announce on Friday it has finally tamed leaking reactors at Fukushima, in what authorities say is a vital step on the long road to recovery, nine months after its nuclear crisis began.

Prime Minister Yoshihiko Noda was expected to tell a disaster-weary public that all reactors at the plant, struck by a titanic tsunami in March, were in a state of cold shutdown and were no longer at any risk of spontaneous fission.