Bringing Japan a step closer to restarting suspended nuclear power operations, reactors 1 and 2 at the Sendai plant in Kagoshima Prefecture on Wednesday became the first to meet strict new safety standards imposed after the March 2011 Fukushima disaster.

The seal of approval was included in a report released by the Nuclear Regulation Authority. But the watchdog’s official approval will come after a month of public comment on the report.

It is still unclear when exactly the utility will return to service. After passing the NRA safety test, the Sendai plant is likely to be the first among the nation’s 48 idled commercial power plants to be returned to service. But Kyushu Electric Co. still faces further hurdles — including the need to obtain backing from local municipalities and the governor of Kagoshima Prefecture — before the reactors can be fired up.

While the Sendai reactors now move to the front of the line to be rebooted, 17 others at different plants nationwide are still being evaluated or waiting to be examined.

Prime Minister Shinzo Abe said the government is ready to reactivate any of the idled reactors across the country once the NRA officially approves safety measures prepared by the nation’s electric power companies, based on new standards introduced after the Fukushima disaster.

“We’d like to promote the reactivation (of nuclear plants) if the NRA conducts scientific and technological evaluations and it is concluded (that they are) safe,” Abe told reporters during a visit to Higashi Matsushima, Miyagi Prefecture, according to Kyodo News.

Though the NRA had said that it would take about six months to finish a single evaluation, the Sendai check took about a year, suggesting it may be unlikely there will be further restarts in the near future.

At a separate news conference in Tokyo, NRA Chairman Shunichi Tanaka insisted that Wednesday’s decision by the authority was not an official green light to reactivate the Sendai plant.

Still, Tanaka said he feels the NRA has finished the most difficult part of the task in examining the safety of the Sendai plant, which is likely to set a precedent for the central government to reactivate other reactors.

“We’ll make further efforts to improve (the safety of the plant), but we have broken the back” of the screening process, he said.

The NRA began enforcing the new safety rules last July, more than two years after the March 11, 2011, mega-quake and ensuing tsunami triggered a triple meltdown at the Fukushima No. 1 nuclear plant.

The new rules require utilities to more strictly assess the potential impact of quakes and tsunami and to significantly reinforce plants’ existing infrastructure, including through building secondary control centers, seawalls, adding auxiliary power and cooling sources, and venting systems that filter radioactive dust.

According to the 400-page report, Kyushu Electric says the maximum jolt that could hit the plant would be of a magnitude of 620 gals. One gal equals a change in the rate of motion of 1 cm per second. The Fukushima plant was hit by a jolt of 675 gals in the 2011 disaster.

The utility has also estimated that the plant could be hit by tsunami as high as 6 meters. Under this estimate, the reactor buildings, which are located 13 meters above sea level, would not be affected. But to protect cooling systems, the utility has built a 10-meter wall around seawater pumps.

Kyushu Electric, however, has yet to finish construction of an earthquake-proof control tower, which played a key role as the Fukushima crisis unfolded.

Under the new safety standards, nuclear plant operators also must prepare measures in the event of severe accidents, such as meltdowns. Before the Fukushima crisis, many had assumed that such accidents were outside the realm of possibility, and such measures were not mandatory.

In addition, the new standards require that the utility consider the possibility of other natural disasters, such as tornadoes and volcanic eruptions, as well as other threats — including terrorist attacks.

The Sendai plant is located in an area surrounded by volcanoes. Kyushu Electric says there are 39 volcanoes within 160 km of the plant, though 25 of these are predicted to remain dormant for the foreseeable future. The remainder could see eruptions, but the possibility is remote, according to the report.

Kyushu Electric submitted the Sendai plant’s application for the NRA check last July. The regulator compiled the report after more than 110 hours of evaluation sessions.

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