Japan Earthquake Expert Says Nuclear Watchdog Ignoring Risk

Seismologist Katsuhiko Ishibashi
Katsuhiko Ishibashi, Kobe University professor and seismologist, has seen his warnings of earthquake dangers come true in devastating fashion at least twice in a country that accounts for about 10 percent of the world’s quakes. Photographer: Yuzuru Yoshikawa/Bloomberg

Japan’s nuclear regulator ignored earthquake risk and its own rules in approving the safety of a nuclear power plant on the western island of Kyushu, said Kobe University professor and seismologist Katsuhiko Ishibashi.

Ishibashi, well-known in Japan for books and papers on earthquake threats that later became reality, said he has filed a formal complaint to the Nuclear Regulation Authority challenging the legality of its decision.

The regulator’s safety approval in September of Kyushu Electric Power Co.’s Sendai nuclear plant opens the way to restart two reactors at the station, possibly this year. They are the first of Japan’s operable reactors to pass the new standards introduced after the Fukushima nuclear disaster in 2011. All reactors in the country have been shut for safety checks for at least 18 months.

Ishibashi has seen his warnings of earthquake dangers come true in devastating fashion at least twice in a country that accounts for about 10 percent of the world’s quakes.

In a 1994 book “A Seismologist Warns” he said building codes were putting Japan’s cities at risk. The following year, the Kobe earthquake buckled bridges, highways, and brought down buildings, killing more than 6,000 people.

Then in 1997, he wrote a report in Japan’s Science Journal where he coined the term “nuclear earthquake disaster.” The paper was written about 14 years before the Fukushima catastrophe, yet reads like a post-mortem of what happened: A major quake knocks out external power to the plant’s reactors and unleashes a tsunami that overruns its defenses, leading to loss of cooling and meltdowns.

Nuclear Restarts

Ishibashi says he doesn’t want his forecasts to play out again.

“I don’t want to experience that again, warning about a disaster and then seeing it take place and causing so much damage,” Ishibashi said at a media briefing in Tokyo on Monday.

Amid pressure from Prime Minister Shinzo Abe’s government to process applications for nuclear plant restarts to help the economy, the NRA is under pressure to give utilities a pass, Ishibashi said. That makes the watchdog less rigorous in examining the safety assessments of utilities’ reactors, he said.

“Professor Ishibashi has his own opinions,” but members of the NRA’s committee made their own judgment, NRA Chairman Shunichi Tanaka said at a media briefing in Tokyo on Tuesday, according to a video of the briefing posted on the regulator’s website.

A Kyushu Electric spokesman said the company doesn’t have a comment regarding Ishibashi’s statements.

Sendai Case

In the case of the Sendai plant, the NRA has allowed the operating company to ignore the risk of an earthquake in the tectonic slab underneath Kyushu, the seismologist said.

Kyushu Electric has also not factored in the risk from a so-called Nankai trough earthquake, Ishibashi said. A Nankai quake is one that could originate in the seas south of Japan’s main island, an eventuality that’s considered high-risk and constantly monitored by the government.

“Kyushu Electric was allowed to select their own criteria for quakes that could hit the plant and they ignored several as outliers -- including a Nankai one,” Ishibashi said. “Taking the Nankai trough earthquake into account is indispensable” in modeling the dangers facing the Sendai plant, he said.

In terms of impact, a Nankai trough quake would cause tremors and ground motion that would last almost ten times as long as Kyushu Electric’s estimates applied for its Sendai plant assessment, Ishibashi said.

The government’s billing of the NRA, formed in the aftermath of the Fukushima disaster, as the world’s most stringent nuclear regulator is simply not true, Ishibashi said. The regulator feels beholden to government policy, which is pro-nuclear and supports restarts, he said.

“The NRA certainly seems to be feeling the pressure from the current administration,” Ishibashi said.

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