12 August 2015

Why was the Sendai nuclear power plant restarted?

Tadahiro Katsuta

Tadahiro Katsuta

Tadahiro Katsuta has a doctorate in plasma physics from Hiroshima University (1997) and is an associate professor at Meiji University in Japan. He is a 2014-2015 visiting fellow...


Two of Japan’s reactors—Units 1 and 2 of the Kyushu Electric Power Company’s Sendai nuclear power plant—have just restarted, and Unit 1 should begin generating electricity on August 14. Like all other Japanese nuclear power plants, Sendai was shut down after the events at Fukushima Daiichi in 2011, in which an earthquake, a tsunami, egregious design mistakes, and a poor safety culture combined to form “a cascade of stupid errors” that led to a triple meltdown.

This is the first restart of any of Japan’s 43 operable commercial reactors since Fukushima, and it is happening despite many unresolved questions concerning nuclear safety regulations. When it comes to safety, the Sendai nuclear power plant is definitely not at the head of the class: The utility owning the power plant was given a pass despite a very problematic history. (At one point, a regulatory commissioner called the plan to restart Sendai “wishful thinking”.)

There is certainly no nationwide re-emergence of nuclear power in Japan. Indeed, there have been vocal public protests against the Sendai restart. One of the protestors even included a former prime minister of Japan.

So, why is it happening? What are the ostensible reasons for a restart? Were they valid?

A three-pointed rationalization. The justification for a restart was based upon three key points: the type of reactors to be used at Sendai were considered inherently “safer;” the chance of a similar natural disaster(s) was considered to be minimal; and the concerns of the local communities were dismissed as inconsequential.

Let us look at each of these items in turn.

Pressurized water reactors are considered inherently safe. Because strict new standards for the regulation of nuclear power plants were imposed in July 2012—the result of the belated adoption of a tougher global standard—Japan’s newly formed Nuclear Regulation Authority deemed that pressurized water reactors (PWRs) such as those used at Sendai were safer than the boiling water reactor technology used at the ill-fated Fukushima Daiichi nuclear plant. Consequently, facilities with PWRs were given a longer time span—five years—to introduce severe accident countermeasures when the new regulation standards come into force.

For example, a nuclear power plant using a pressurized water reactor is not required to immediately install a filtered containment venting system to prevent large-scale radioactive contamination to the environment if the containment vessel inside is damaged. The Nuclear Regulation Authority’s reasoning is that the risk of containment vessel damage is low in a pressurized water reactor because it is so much larger than in a boiling water reactor, thus allowing considerably more time before any accident measures must be put into effect. Building on this logic, the agency then gave a temporary exemption to the requirement to install the venting system to any facility using PWRs. This relieved the plant operators of heavy burdens in terms of both finances and preparatory work. All 10 of the nuclear power plants (representing six different electric companies) that applied for the waiver use pressurized water reactors.

But PWRs are not inherently safe at all; for example, their steam generators are a serious concern. In 1991, the steam generator in the pressurized water reactor at Mihama Unit 2 of Kansai Electric Power in Japan was damaged, and the emergency core cooling system had to activated. Though caused by something as simple as the failure of the mount of a metal fitting, the resulting accident was rated at Level 3, or “serious incident,” on the seven levels of the International Nuclear Event Scale. Similarly, in 2013, Unit 2 and Unit 3 of the San Onofre nuclear power plant in California had to be closed due to a radiation leak from the plant’s virtually new steam generators; the two units subsequently had to be retired and the plant is now in the process of a costly decommissioning, predicted to cost $3 billion. And San Onofre used pressurized water reactor technology.

Natural disasters can be predicted. There are many glaring problems with this argument, not the least of which is the tendency of, say, volcanoes to behave in ways we don’t foresee. This is of major concern in Japan, which sits on the Pacific Ring of Fire, where tectonic plates interact and a large chunk of the planet’s volcanic eruptions and earthquakes takes place. Kyushu Electric Power claims that volcanic eruptions can be readily predicted, and the Nuclear Regulation Authority accepted this argument. But many volcanologists insist that it is scientifically impossible to predict the eruption of a volcano—and there are many volcanoes and calderas near the Sendai nuclear power plant. According to a survey conducted by Kyushu Electric Power, catastrophic eruptions have been occurring on a 90,000-year cycle at the Aira Caldera, located 53 kilometers, or about 33 miles, from the Sendai site, with the latest eruption about 30,000 years ago. (There have been many smaller, near-continuous eruptions in the caldera since 1955.) Furthermore, sediment from the pyroclastic flow of a volcano has been discovered only 5 kilometers, or roughly 3 miles, from the reactors at Sendai.

Another problem comes from trying to determine the maximum acceleration likely to occur at the time of an earthquake. This is an issue of tremendous concern, because there are about 1,500 earthquakes of varying sizes in Japan every year. In the words of the World Nuclear Association: “Because of the frequency and magnitude of earthquakes in Japan, extra attention is paid to seismic activity in the siting, design, and construction of nuclear power plants. The seismic design of such plants is based on criteria far more stringent than those applying to non-nuclear facilities.”

Yet one of the reasons that the authority announced fast-track approval for Sendai was based upon a recalculation of the largest earthquake that could reasonably be expected to occur at the site of this nuclear power plant—which was found to be larger and more devastating than before, based upon the known seismicity of the area and local active faults. Known as “peak ground acceleration,” this figure is expressed in the number of centimeters per second squared, also known as “Galileo units” or Gal. Setting the value of a specific region’s peak ground acceleration is difficult scientifically; guessing just how bad an earthquake can get is the cause of many safety design revisions and much expense. In the case of the Kyushu Electric Power Company, however, the company not only said on its restart application that an earthquake was likely to be worse than previously expected (620 Gal rather than the earlier estimate of 540 Gal), it cavalierly said that its current reactor would be able to handle the higher figure. The NRA apparently considered this platitude about the resiliency of the company’s Sendai plant to be a statement of scientific fact and sufficient in terms of safety.

And some seismologists insist that an earthquake at Sendai is likely to be even more severe—they say that the earth could shake much more than 620 centimeters (about 20 feet) per second squared. For example, Katsuhiko Ishibashi, a Kobe University professor and seismologist, has been warning about the problem of nuclear power plant accidents caused by earthquakes since his first book on the topic in 1994—17 years before what happened at Fukushima Daiichi. (Ishibashi even coined a term in the Japanese language to describe the problem: “gempatsu shinsai,” or “nuclear earthquake disaster.”) He insists that the intensity of a more severe earthquake is underestimated because the current value does not take into consideration other phenomena, such as an interplate earthquake.

And in any case, the 620 Gal figure comes from earthquake data collected from the north end of Japan, while the Sendai nuclear power plant is located at the south end, where conditions may be different. So, we don’t precisely know just how severe the peak ground acceleration will be at Sendai.

There is no available scientific literature on the influence of a major earthquake on delicate devices such as the steam generators used in pressurized water reactors.

Concerns of the local communities were dismissed. After the Nuclear Regulation Authority granted its approval in regards to the safety requirements, the final hurdle was to secure approval from two of the local governments: Kagoshima prefecture and Satsumasendai city. If they agreed, then the Sendai facility could restart.

Other neighboring communities, including six cities and two towns, had asked that the prefecture and the city include them in the list of “local governments of the nuclear power plant site.” They based their request on the fact that they would likely be affected by any radioactive contamination—after all, the plume caused by the Fukushima accident spread over 250 kilometers (155 miles) from the reactor site. But only those communities within 8 to 10 kilometers (about 5 to 6 miles) from the Sendai nuclear power plant were allowed to participate.

And even those within that radius were sometimes barred from having their concerns heard. A neighboring city, Ichikikushikino, is located just 5 kilometers (about 3 miles) from the Sendai plant, but that city’s request to be heard was denied by the governor of Kagoshima prefecture governor, Yuichi Ito, and by the mayor of Satsumasendai city, Hideo Iwakiri. This refusal is assumed to be based on two reasons: In addition to the difficulty of summarizing the different opinions on the nuclear restart, prefecture and city officials were concerned about having to decrease their own constituents’ share of the subsidy benefits that are to be provided by the plant to local governments. In the end, only Kagoshima prefecture and Satsumasendai city approved the restart in November 2014.

Other actions by the prefecture governor caused problems, as well. The prefecture’s disaster prevention plan was supposed to include an evacuation program for people requiring special assistance in any medical or welfare facilities located within 30 kilometers (about 20 miles) from the Sendai nuclear power plant. The prefectural governor, however, declared that an area within 10 kilometers (roughly 6 miles) from the power plant was more than sufficient as the target area for this program. Therefore, the number of applicable facilities was reduced from 244 facilities to to only 17 facilities, or less than one-tenth the original number. Furthermore, an evacuation facility that had been constructed by repairing an old elementary school, Yorita Elementary, turned out to have insufficient protective measures against radiation, even though the total construction cost for the facility was the equivalent of $760,000.

The real reasons for the restart. The decision to restart the reactor at Sendai is probably based upon the “dismal science:” economics.

It seems that financial considerations and worries about the health of the national and local economies triumphed over safety concerns; an article in the Japan Times says that when Kyushu Electric tried to turn to other means of generating electricity—such as thermal power—its costs more than doubled. “The huge costs have weighed heavily on its earnings. The company is aiming to shore up its earnings by reactivating idled nuclear power reactors. Kyushu Electric expects that the restart of the Sendai Number 1 reactor will save the company about 7.5 billion yen (over $60 million) per month.”

Kyushu Electric Power had previously tried raising the price of electricity after their nuclear power plant was stopped, but that still was not enough—their deficit continued. The best hope of profitability comes from restarting nuclear power plants.

This concern for their bottom line may be understandable, but it seems to come at the expense of public safety and open, democratic, rational decision-making. Kyushu Electric Power has used questionable means to promote its agenda. For example, at an informational meeting for local residents about nuclear power plant operation only three months after the Fukushima accident, Kyushu Electric Power sent in undercover employees pretending to be ordinary citizens, who then stood up and spoke in favor of nuclear power. The company also tried to manipulate public opinion by sending in “fake e-mails” in support of the restart of nuclear power plants to a television broadcaster. The president of Kyushu Electric Power resigned after the ruses were discovered.

Meanwhile, Kyushu Electric Power still refuses to hold talks with citizen groups and neighboring local governments, even after the plant has been cleared to restart. They also refused an offer from nearly 100 citizen groups this March to hold a discussion, and did not accept a petition containing more than 100,000 signatures. The company continues to refuse the requests of many local governments within the 30 kilometer (20 miles) radius of the Sendai site.

Economics also played a role in another way: The prefecture and the nearest city are financially dependent on nuclear energy. For a long time, the prefecture governor has been clearly stating that he endorses the restart. After the prefectural assembly election this April, he revealed that the reason the restart was approved in November 2014 was to avoid having it become an election issue.

Satsumasendai city receives more than $12 million in grants annually from the nuclear industry, which it uses to pay for its public and educational facilities, receiving about $270 million over the years. According to the Satsumasendai Chamber of Commerce and Industry, the overall economic benefit of the restart of the Sendai nuclear power plant is approximately $25 million to the local economy yearly.

There are also questions of transparency in the dealings of local government authorities with Kyushu Electric Power. According to an article published this January by the Asahi Shimbun newspaper, construction companies run by members of the Kagoshima prefectural assembly received 26 orders for construction work at Sendai, representing $2.5 million of work, in the three years since the Fukushima accident. Not surprisingly, these members of the prefectural assembly endorsed the restart of the Sendai nuclear power plant.

According to a survey conducted this May by a major local newspaper, Minami-Nippon Shimbun, 59.9 percent of those polled were against a restart of the Sendai nuclear power plant. But their opinions may not be regarded as important because they have no economic significance. In this way, strict regulations are not being applied to nuclear decisions, even after the Fukushima accident. Economics was considered more important than human life: That is why the Sendai nuclear power plant was able to restart.

Editor's note: In the time since this article was published, Japan’s weather agency on Saturday told thousands of residents to prepare for a possible evacuation as it upgraded a volcanic eruption warning. Officials raised their alert to "extremely high"—its second-highest level—after picking up increasing seismic activity around the volcano Sakurajima, which sits just off the coast of Kagoshima, a city of more than 600,000 people. The volcano is about 50 kilometres (31 miles) from the Sendai nuclear reactor.