The Tokai No. 2 nuclear power plant in Ibaraki Prefecture, which recently got the green light from the Nuclear Regulation Authority to operate beyond a 40-year lifespan, will be a test case for whether reactor operators can obtain consent for their restart from not only the host municipalities but those in the surrounding area that would also be affected by a Fukushima-level accident. Last March, Tokai No. 2's operator, Japan Atomic Power Co., concluded an agreement with six municipalities in the prefecture, including the host village of Tokai, that it would obtain their consent before restarting the idled plant — the first of its kind among nuclear plant operators, which normally seek the approval of only the host municipality and prefecture for a restart.

The Tokai No. 2 plant, which began commercial operations in November 1978, is the first nuclear plant hit by the tsunami generated by the March 2011 Great East Japan Earthquake to win the NRA's nod for a restart. The plant was flooded by the tsunami and lost the supply of electricity to cool its reactor but averted a meltdown because part of the emergency backup power supply remained intact. Idled since that year, the plant would have reached the 40-year mandatory limit on its operation at the end of this month and faced decommissioning unless the NRA approved the 20-year extension.

A rule established in the wake of the March 2011 crisis restricts the operation of a nuclear plant to 40 years from its launch — a limit that can be extended once, for up to 20 years, with NRA approval. While extension of a plant's life beyond 40 years was initially called an "exception," the NRA has already given the go-ahead for extending the operation of four reactors, including the unit at Tokai No. 2. Power companies have sought the 20-year extension for aging reactors with large power-generation capacities while choosing to decommission less-powerful units that, if their operation is extended, would have no chance of recouping the huge investments needed for the safety upgrades required for an extension.