29 Avril 2016
April 29, 2016
THE ASAHI SHIMBUN
Kyushu Electric Power Co. brushed aside safety concerns expressed in thousands of phone calls and e-mails, saying its Sendai nuclear plant in Kagoshima Prefecture faces no danger from the quakes rattling the southern main island.
The Nuclear Regulation Authority also supports the utility’s stance that there is no need to shut down the nuclear plant, even as a safety precaution during the seismic activity.
“Nuclear power is energy defined as necessary in the nation’s basic energy plan,” Kyushu Electric President Michiaki Uryu said at a news conference in Fukuoka on April 28. “We are operating (the Sendai plant) after confirming its safety and concluding that there is no problem with continuing to operate it.”
The news conference was held to announce the utility’s earnings for fiscal 2015, which included its first net profit in five years.
Two reactors at the Sendai plant in Satsuma-Sendai—the only ones running in the nation—cleared tougher nuclear safety regulations set after the 2011 Fukushima disaster.
Kagoshima Prefecture lies immediately south of Kumamoto Prefecture, where most of the earthquake activity has occurred since April 14.
The reactors at the Sendai plant must be shut down when ground acceleration in a horizontal direction of 160 gal is registered on the basement floor of the reactor auxiliary building.
When the largest quake in the series, a magnitude-7.3 temblor that struck Kumamoto Prefecture on April 16, ground acceleration of up to 8.6 gal was recorded at the Sendai plant. No irregularities have been detected at the nuclear plant, according to Kyushu Electric.
Although the figure is well below the level that requires an emergency shutdown, concerned citizens maintain that the utility should suspend operations as an extra precaution for an event unforeseen by authorities.
Over a week from April 15, the day after a magnitude-6.5 earthquake struck Kumamoto Prefecture, Fukuoka-based Kyushu Electric was flooded with about 5,000 e-mails and phone calls seeking a halt to operations at the Sendai plant.
Kyushu Electric officials acknowledge that without the Sendai nuclear plant, the company would still have enough electricity to supply Kyushu this summer, even if it proves to be one of the hottest in recent years.
But the utility is eager to keep the Sendai plant online because running a nuclear power plant is cheaper than buying the fuel needed to operate a thermal power plant.
Kyushu Electric had relied on nuclear energy for 40 percent of its electricity supply before the Fukushima disaster, one of the highest ratios among the regional power companies.
Kyushu Electric’s bottom line was hit hard after all reactors in Japan were shut down as a precaution following the meltdowns at the Fukushima plant.
But since the restart of the Sendai plant, which a Kyushu Electric senior official called a “powerful card,” the company has been saving 10 billion yen ($92.6 million) to 13 billion yen a month in operating expenses.
Uryu is already pushing plans for the company’s Genkai nuclear plant in Saga Prefecture.
“We are striving to achieve a restart of the Genkai plant as early as possible,” he told the news conference.
The NRA stands firm on its decision that the Sendai plant is safe amid the series of the quakes and that it does not need to order a suspension of operations.
“There are no compelling scientific grounds,” NRA Chairman Shunichi Tanaka said after an emergency meeting about the plant’s operations on April 18. “We are not going to shut down the plant just because of calls from the public or politicians. What has been going on is within our expectations.”
According to Kyushu Electric, the Sendai plant is designed to withstand a maximum ground acceleration of 620 gal. This figure was determined after experts studied various scenarios based on geological features at the plant and surrounding areas.
The company also studied the possible impact from a magnitude-8.1 earthquake that strikes in connection with the Futagawa and Hinagu fault lines. Seismologists say those two fault lines slipped in Kumamoto Prefecture, triggering the ongoing seismic activity.
For an earthquake of that size, Kyushu Electric projected a maximum ground acceleration of about 160 gal.
Even if the Sendai plant loses its ability to cool the reactors after powerful earthquakes, the operator is believed to be prepared to prevent a severe accident involving the release of radioactive substances by cooling the reactors using fire engines, power supply vehicles and other sources under the new regulations.
But those erring on the side of caution note that the magnitude-9.0 Great East Japan Earthquake on March 11, 2011, spawned a tsunami that Tokyo Electric Power Co., operator of the Fukushima No. 1 plant, was clearly unprepared for.
And two earthquakes 28 hours apart in the recent series of temblors both measured a maximum intensity of 7 on the Japanese seismic scale in Kumamoto Prefecture, an event unprecedented in Japan.
In the heavily damaged town of Mashiki in Kumamoto Prefecture, power supply vehicles, which were operating in recovery efforts after the April 14 earthquake, were toppled in the more powerful earthquake two days later. Roads were severed, and a railway network was paralyzed over a wide area.
Residents sought refuge outdoors and in their cars, fearing the strong aftershocks could collapse buildings used as evacuation centers.
Critics questioned whether workers trying to prevent a possible quake-induced crisis at the Sendai plant would be able to continue with their efforts if another powerful earthquake struck the plant.
They also voiced concerns about government evacuation guidelines in the event of a nuclear accident, namely instructions to residents living within a 5-30 kilometer radius of a damaged plant to remain indoors.
NRA chief Tanaka said such a situation was unlikely to occur at the Sendai plant.
“There is no active geological fault beneath the Sendai plant,” he said at a news conference on April 27. “The plant is also designed to be quake-proof, so people do not need to worry about those things.”
(This article was compiled from reports by Shuhei Shibata, Masanobu Higashiyama and