Japanese seismologists warn of possible active fault line dividing Ohi reactors

Author: 1 Comment Share:

Seismic modeling by Japan’s nuclear regulator did not properly take into account active fault lines near the Ohi plant

Japan restarted one of its nuclear reactors on Sunday for the first time since shutting down all the country’s reactors in the wake of the Fukushima Daiichi nuclear disaster.  The critical decision made by Prime Minister Noda has drawn unusually vocal public opposition in normally compliant Japan, and created a deep division in public opinion.

Throngs of people grew in number and in resolve throughout the week around Japanese Prime Minister Noda’s official residence, chanting, “Saikado hantai,” or “Opposition to restart!”

“I’m watching this with a tense feeling,” the official, Seishu Makino of the Trade Ministry, said of the restart, according to Japanese news reports. “The government has taken a necessary step forward despite controversy that has divided the nation.”

The Unit 3 reactor operated by the Kansai Electric Power Company reached so-called criticality at 6 a.m. Monday morning, after the operation was resumed at 9 p.m. Sunday night. The plant is scheduled to generate electricity as early as July 4. The utility intends to restart the 1,180-megawatt No. 4 reactor at the plant as early as July 17.

Experts warn Japan’s nuclear industry underestimating the F-6 Shuttered Zone (fault)

Despite having been slated for restart, the two reactors at the Ohi nuclear plant find themselves once again under intense scrutiny, as seismologists warn that Japan’s nuclear regulator has not replicated accurate seismic modeling for the plants.

Katsuhiko Ishibashi, a seismologist at Kobe University, claims that the authorities have underestimated the seismic threat, telling reporters, “The stress tests and new safety guidelines for restarting nuclear power plants both allow for accidents at plants to occur.” Ishibashi told reporters. “Instead of making standards more strict, they both represent a severe setback in safety standards.”

At a press conference on June 7th, Haruki Madarame, Chair of the Nuclear Safety Commission stated, “If brand new findings [related to fault lines around the Ohi nuclear power plant] have been found, the Nuclear and Industrial Safety Agency (NISA) should thoroughly undertake a reassessment.”

Investigations by Japanese mainstream media journalists discovered that the operator, Kansai Electric, had not turned over all of the seismic data that had been requested of them, as they “could not locate it.”

Meanwhile, “new findings” were presented by Mitsuhisa Watanabe, a tectonic geomorphology professor from Tokyo University, at a press conference on June 28th where he warned that the central government had not taken all possible fault data into consideration, and shared concerns about is the presence of a shattered zone called “F6” which runs underground between Units 2 and 3 of the Ohi Nuclear Power Plant.

There is evidence that infers the bedrock and the upper layer of earth around the F-6 fault line shifted at the same time, and the Tokyo professor considers this to be a “classic active fault structure,  though KEPCO does not agree.

KEPCO and nuclear safety regulators have shown some data pertinent to the southern side profile of the fault line, but they have not disclosed information related the north side profile of the fault line, which is where experts think may  indicate the possibility of active fault lines.  Moreover, the F-6 fault line crosses the one of the very important facility emergency cooling water lines.  If this fault line moves, they will not able to cool the reactor on emergency.

Southern side trench picture which was indicated before at the governments commissions before F-6 disclosure.
Top snady soil has moved along the rock layer. Surface of the fault, there are clay attached. ( red square in picture)—1cm film like yellow clay attached – infers recent movement activity of an active fault

“The expertise and neutrality of experts advising Japan’s Nuclear Industrial Safety Agency are highly questionable,” Watanabe said.  He has asked that the government undertake an onsite examination of the geology. He also states, for the length of time necessary for the investigation he states that, “it can be undertaken thoroughly in a few days.”

Chief Researcher Yuichi Sugiyama of the National Institute of Advanced Industrial Science and Technology (AIST) who is also a committee member of NISA’s Expert Committee admitted that, “The government’s Safety Examination [the government examination undertaken during the licensing procedure for the Ohi site] was not able to investigate all of the operator’s [Kansai Electric’s] inspection data.

It is extremely important to undertake a re-examination of all of the data and also to undertake an onsite investigation of the site.”

Some congressmen and citizens visited the Ohi plant on June 27th for an onsite inspection.  It only takes few days to check the possibility of active fault lines ( F-6),  and they found out there are 3 places where easily they can test the soil under the asphalt road.

A committee member of the [Fukui] Prefecture Nuclear Power Safety Expert Committee stated when interviewed by the Yomiuri Newspaper that, “In the midst of this much concern and interest regarding restart, in order to make a judgment concerning safety which will be accepted by the general public, this issue is something that must be investigated.”

Trade Minister Yukio Edano did not share the same sentiment in a press conference on June 29th.  He said despite the recognition of the new findings, at the moment, they do not affect the plans for restart.


Editors Note:  Many thanks to Kishiko Suzuki, who spent personal time and effort to provide most of the translations from Japanese to English for me, I am very grateful.



Source: Asahi

Source: Reuters

Source: Asahi

Source: Bloomberg

Source: Japan Daily Press

Source: Asahi

Source: The New York Times

Source: Asahi

Source: NIRS

Source: DL Dropbox

Previous Article

San Onofre shutdown offers firsthand look at nuclear energy costs vs benefits in California

Next Article

Opinions on nuclear power dominate Japan and spill over international boundaries