The decision last week by the Hiroshima High Court to order Shikoku Electric Power Co. to suspend operations of a reactor comes as yet another reminder of the many hurdles faced by nuclear power plants in the wake of the 2011 Fukushima disaster. Power companies should re-examine their strategy of counting on restarting their idled reactors, which will reduce their imported fuel costs, as a key to rebuilding their financial health. The government, meanwhile, should review the feasibility of its energy plan that envisions having nuclear power account for more than 20 percent of the nation's electricity supply in 2030.

In the first high court decision to issue such an order, the Hiroshima High Court ruled that reactor No. 3 at Shikoku Electric's Ikata nuclear power plant in Ehime Prefecture cannot be restarted, saying the potential impact of a major volcanic eruption of Mount Aso in central Kyushu — about 130 km away — on the plant's safety has not been properly assessed. Shikoku Electric was operating the reactor since August last year, following the Nuclear Regulation Authority's approval of its updated measures against big natural disasters, until it was taken offline for a routine inspection. The court injunction remains in effect through the end of next September, and the company's plan to resume its operation next month is now doomed unless another court decision reverses the order.

Since the nation's nuclear power plants were taken offline following the March 2011 meltdowns at Tokyo Electric Power Company Holding's Fukushima No. 1 plant, only five reactors at plants run by Kyushu Electric, Kansai Electric and Shikoku Electric have been reactivated following NRA screening based on a 2013 revamped nuclear power plant safety standard. Under its basic energy plan, the government sets a target of having nuclear power account for 20 to 22 percent of Japan's electricity supply in 2030, but that would require 25 to 30 reactors in operation by that point.