Onagawa: The Japanese nuclear power plant that didn’t melt down on 3/11

Three years ago, the biggest recorded earthquake in Japanese history hit Tohoku prefecture, leaving more than 20,000 people dead or missing. On the heels of the destructive magnitude 9.0 earthquake came a tsunami that reached a run-up height of 30 meters in some areas, sweeping entire towns away in seconds.

Within the affected area were three nuclear power plants: the Fukushima Daiichi and Daini nuclear power plants operated by the Tokyo Electric Power Company (Tepco), and the Onagawa Nuclear Power Station operated by the Tohoku Electric Power Company. While the three power stations shared similar disaster conditions, nuclear reactor types, dates of operation, and an identical regulatory regime, their fates were very different. The Fukushima Daiichi plant experienced fatal meltdowns and radiation releases. Fukushima Daini was damaged by the earthquake and tsunami, but the heroic efforts and improvisations of its operators resulted in the cold shutdown of all four operating reactors. Onagawa managed to remain generally intact, despite its proximity to the epicenter of the enormous earthquake.

“The earthquake and tsunami of March 11, 2011, were natural disasters of a magnitude that shocked the entire world. Although triggered by these cataclysmic events, the subsequent accident at the Fukushima Daiichi Nuclear Power Plant cannot be regarded as a natural disaster. It was a profoundly manmade disaster—that could and should have been foreseen and prevented.” - Kiyoshi Kurokawa, “Message from the Chairman,” The Official Report of The Fukushima Nuclear Accident Independent Investigation Commission

Everyone knows the name Fukushima, but few people, even in Japan, are familiar with the Onagawa power station. Fewer still know how Onagawa managed to avoid disaster. According to a report by the International Atomic Energy Agency mission that visited Onagawa and evaluated its performance, “the plant experienced very high levels of ground motion—the strongest shaking that any nuclear plant has ever experienced from an earthquake,” but it “shut down safely” and was “remarkably undamaged.”

Most people believe that Fukushima Daiichi’s meltdowns were predominantly due to the earthquake and tsunami. The survival of Onagawa, however, suggests otherwise. Onagawa was only 123 kilometers away from the epicenter—60 kilometers closer than Fukushima Daiichi—and the difference in seismic intensity at the two plants was negligible. Furthermore, the tsunami was bigger at Onagawa, reaching a height of 14.3 meters, compared with 13.1 meters at Fukushima Daiichi. The difference in outcomes at the two plants reveals the root cause of Fukushima Daiichi’s failures: the utility’s corporate “safety culture.”

Higher ground. While the Fukushima Daiichi and Onagawa plants are similar in many ways, the most obvious difference is that Tohoku Electric constructed Onagawa’s reactor buildings at a higher elevation than Tepco’s Fukushima reactor buildings. Before beginning construction, Tohoku Electric conducted surveys and simulations aimed at predicting tsunami levels. The initial predictions showed that tsunamis in the region historically had an average height of about 3 meters. Based on that, the company constructed its plant at 14.7 meters above sea level, almost five times that height. As more research was done, the estimated tsunami levels climbed higher, and Tohoku Electric conducted periodic checkups based on the new estimates.

Tepco, on the other hand, to make it easier to transport equipment and to save construction costs, in 1967 removed 25 meters from the 35-meter natural seawall of the Daiichi plant site and built the reactor buildings at a much lower elevation of 10 meters. According to the National Diet of Japan’s Fukushima Nuclear Accident Independent Investigation Commission (NAIIC), the initial construction was based on existing seismological information, but later research showed that tsunami levels had been underestimated. While Tohoku Electric learned from past earthquakes and tsunamis—including one in Chile on February 28, 2010—and continuously improved its countermeasures, Tepco overlooked these warnings. According to the NAIIC report, Tepco “resorted to delaying tactics, such as presenting alternative scientific studies and lobbying.”

Tepco’s tsunami risk characterization and assessment was, in the judgment of one the world’s renowned tsunami experts, Costas Synolakis, director of the Tsunami Research Center at the University of Southern California, a “cascade of stupid errors that led to the disaster.”

Emergency response. Tohoku Electric also took a different approach to emergency response—one that was more organized, collaborative, and controlled than Tepco’s. Tohoku Electric established an emergency response center at the Onagawa plant, as well as at company headquarters, immediately after the earthquake. Throughout the disaster, headquarters supported the plant operators minute by minute. Supervisors and chief engineers were dispatched to the main control rooms of the damaged reactors to make decisions, and information was sent in a timely manner to all levels of the response team.

Why did the Tohoku Electric team remain more poised and unified than their counterparts at Tepco? According to the Nippon Telegraph and Telephone Facilities Research Institute, Yanosuke Hirai, vice president of Tohoku Electric from 1960 to 1975—a time period that preceded the 1980 groundbreaking at Onagawa—was adamant about safety protocols and became a member of the Coastal Institution Research Association in 1963 because of his concern about the importance of protecting against natural disasters. With a senior employee in upper management advocating forcefully for safety, a strong safety culture formed within the company. Representatives of Tohoku Electric participated in seminars and panel discussions about earthquake and tsunami disaster prevention held by the Japan Nuclear Energy Safety Organization. The company implemented strict protocols for disaster response, and all workers were familiar with the steps to be taken when a tsunami was approaching.

These initiatives were not part of Tepco’s culture. The company had a mindset that its domination in the electricity industry was an indication of flawlessness. After the disaster, Hasuike Tooru, the former president of Tepco, described how management decided to lengthen the expected lifetime of power plants, even if there were severe safety consequences.

Safety culture. Government investigations of the Fukushima accident, as well as a statement by US Nuclear Regulatory Commission (NRC) chairwoman Allison MacFarlane, have explicitly acknowledged the vital role of safety culture, which the NRC has defined as “the core values and behaviors resulting from a collective commitment by leaders and individuals to emphasize safety over competing goals to ensure protection of people and the environment.”

The NAIIC report described the Fukushima accident as “made in Japan,” because Japan’s nuclear industry failed to absorb the lessons learned from Three Mile Island and Chernobyl. In the words of NAIIC chairman Kiyoshi Kurokawa, “It was this mindset that led to the disaster.” Safety culture has also been implicated as a primary root cause of the Chernobyl accident.

The Fukushima Daiichi Nuclear Power Station’s meltdowns were not due to the natural disaster, but rather to a series of decisions by Tepco not to be proactive with safety, dating back to when the reactors were being constructed. With most other factors being similar, it was Tokohu Electric’s overall organizational practices and safety culture that saved the day for Onagawa. If safety and disaster response had been properly recognized, addressed, and implemented at Fukushima Daiichi—as they were within Tohoku Electric’s corporate safety culture—perhaps the disastrous meltdowns would have been prevented.

Editor's note: This article is adapted from a research paper based on material available in the public domain in Japan and the United States; the full version of the paper can be found here.

 

© 2014

Agreement Could Catapult New Nuclear Reactor Technology Forward

On Feb. 17, Babcock & Wilcox Co. (B&W) and TerraPower announced the signing of a Memorandum of Understanding (MOU) to support the development of the traveling wave reactor (TWR).

The TWR is a Generation IV commercial reactor design that uses depleted uranium as fuel. The 1,150-MW liquid sodium-cooled fast reactor is different from typical light water reactors because it is able to operate for an extended period using only uranium 238 (U-238) rather than uranium 235 (U-235).

In the past, U-238—a by-product of the enrichment process—had been set aside as waste. The new design could enable a TWR to get up to 50 times more energy out of every pound of mined uranium than could otherwise have been utilized with conventional light water reactor technology.

B&W expects to provide TerraPower with support in many areas, including design and fabrication, fuel services, engineering, operations support, licensing, and testing. It appears that B&W will also continue working on its other nuclear development project, mPower, which is a Generation III++ small, modular reactor (SMR) based on pressurized water reactor technology and standard fuel enriched to 5% U-235.

The TWR and SMR are not the only new nuclear design technologies under development. Prior to the Fukushima disaster, the nuclear industry was flush with new ideas. Now Generation IV designs seem to be picking up steam again.

“We have a long tradition of providing industry leading engineering, manufacturing and services and look forward to supporting TerraPower and to participating in the development of the next generation technology,” said Joe Zwetolitz, president of B&W Nuclear Energy Inc.

“This MOU with B&W makes it possible for us to tap the nuclear industry’s excellence and keep American companies active in the international supply chain for advanced nuclear energy technologies,” Doug Adkisson, senior vice president for TerraPower added.

If all goes as planned, the partners will utilize fast reactor technology, high-performance computing simulations, and real testing in current fast reactor test facilities to make the TWR concept a reality. More

 

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AREVA, EDF sign accords for Saudi nuclear program

RIYADH - EDF and AREVA signed two sets of agreements aimed at supporting the Saudi nuclear energy program on Monday, coinciding with the visit of French President François Hollande's to Riyadh. The two companies have signed Memorandums of Understanding (MoUs) with 5 Saudi industrial partners - Zamil Steel, Bahra Cables, Riyadh Cables, Saudi Pumps, Descon Olayan.

The agreements aim to develop the industrial and technical skills of local companies. They reflect AREVA and EDF's desire to build an extended network of Saudi suppliers for future nuclear projects in the country.

A second series of agreements signed with 4 Saudi universities - King Saud University in Riyadh, Dar Al Hekma College and Effat University in Jeddah and finally Prince Mohammed bin Fahd University in Al-Khobar - are intended to contribute to the development of nuclear expertise in the Kingdom.

These agreements follow on from the previous operations organized by EDF and AREVA, through their joint office in Riyadh. These include the "Suppliers' Days" in March and October 2013, the visit to France by Saudi industrial companies in November, the agreement signed with the local professional training institute (NIT) in July 2013, the visits to French nuclear facilities organized for Saudi university faculty members in June 2013 and internship offers made to Saudi students since the summer.

EDF CEO Henri Proglio said: "These new agreements underline EDF and AREVA's commitment alongside the Kingdom of Saudi Arabia to enable it to successfully implement its national energy strategy and in particular to develop its future nuclear program by contributing to the development of a local network of manufacturers and by training qualified engineers."

Luc Oursel, President and CEO of AREVA, added: "These agreements demonstrate the common will of EDF and AREVA to establish a true long-term partnership with the Kingdom of Saudi Arabia. They will enable the country to build a strong industrial base and a robust skills management program."

The EDF group, one of the leaders in the European energy market, is an integrated energy company active in all areas of the business: generation, transmission, distribution, energy supply and trading. The Group is the leading electricity producer in Europe. In France, it has mainly nuclear and hydropower generation facilities where 95.9 percent of the electricity output is CO2-free.

AREVA supplies advanced technology solutions for power generation with less carbon. Its expertise and unwavering insistence on safety, security, transparency and ethics are setting the standard, and its responsible development is anchored in a process of continuous improvement. Ranked first in the global nuclear power industry, AREVA's unique integrated offering to utilities covers every stage of the fuel cycle, nuclear reactor design and construction, and operating services. The group is actively developing its activities in renewable energies - wind, bioenergy, solar and energy storage - to become a European leader in this sector. More

 

 

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Experts say nuclear power needed to slow warming

Some of the world's top climate scientists say wind and solar energy won't be enough to head off extreme global warming, and they're asking environmentalists to support the development of safer nuclear power as one way to cut fossil fuel pollution.

Traveling Wave Reactor

Four scientists who have played a key role in alerting the public to the dangers of climate change sent letters Sunday to leading environmental groups and politicians around the world. The letter, an advance copy of which was given to The Associated Press, urges a crucial discussion on the role of nuclear power in fighting climate change.

Environmentalists agree that global warming is a threat to ecosystems and humans, but many oppose nuclear power and believe that new forms of renewable energy will be able to power the world within the next few decades.

That isn't realistic, the letter said.

"Those energy sources cannot scale up fast enough" to deliver the amount of cheap and reliable power the world needs, and "with the planet warming and carbon dioxide emissions rising faster than ever, we cannot afford to turn away from any technology" that has the potential to reduce greenhouse gases.

The letter signers are James Hansen, a former top NASA scientist; Ken Caldeira, of the Carnegie Institution; Kerry Emanuel, of the Massachusetts Institute of Technology; and Tom Wigley, of the University of Adelaide in Australia.

Hansen began publishing research on the threat of global warming more than 30 years ago, and his testimony before Congress in 1988 helped launch a mainstream discussion. Last February he was arrested in front of the White House at a climate protest that included the head of the Sierra Club and other activists. Caldeira was a contributor to reports from the Intergovernmental Panel on Climate Change, Emanuel is known for his research on possible links between climate change and hurricanes, and Wigley has also been doing climate research for more than 30 years.

Emanuel said the signers aren't opposed to renewable energy sources but want environmentalists to understand that "realistically, they cannot on their own solve the world's energy problems."

The vast majority of climate scientists say they're now virtually certain that pollution from fossil fuels has increased global temperatures over the last 60 years. They say emissions need to be sharply reduced to prevent more extreme damage in the future.

In 2011 worldwide carbon dioxide emissions jumped 3 percent, because of a large increase by China, the No. 1 carbon polluting country. The U.S. is No. 2 in carbon emissions.

Hansen, who's now at Columbia University, said it's not enough for environmentalists to simply oppose fossil fuels and promote renewable energy.

"They're cheating themselves if they keep believing this fiction that all we need" is renewable energy such as wind and solar, Hansen told the AP.

The joint letter says, "The time has come for those who take the threat of global warming seriously to embrace the development and deployment of safer nuclear power systems" as part of efforts to build a new global energy supply.

Stephen Ansolabehere, a Harvard professor who studies energy issues, said nuclear power is "very divisive" within the environmental movement. But he added that the letter could help educate the public about the difficult choices that climate change presents.

One major environmental advocacy organization, the Natural Resources Defense Council, warned that "nuclear power is no panacea for our climate woes."

Risk of catastrophe is only one drawback of nuclear power, NRDC President Frances Beinecke said in a statement. Waste storage and security of nuclear material are also important issues, he said.

"The better path is to clean up our power plants and invest in efficiency and renewable energy."

The scientists acknowledge that there are risks to using nuclear power, but say those are far smaller than the risk posed by extreme climate change.

"We understand that today's nuclear plants are far from perfect." More

 

 

General Atomics in contest for SMR funds

General Atomics has announced that it is among the small modular reactor (SMR) developers seeking funds from the US Department of Energy. It has submitted its Energy Multiplier Module (EM2), a helium-cooled high-temperature reactor.

The Department of Energy (DoE) intends to fund up to two designs for SMRs through a cost-shared partnership which will support first-of-a-kind engineering, design certification and licensing. With the first round of funding allocated to B&W in late 2012, the DoE is now reviewing applications under a second round.

General Atomics (GA) has now confirmed that it is one of several SMR developers to have submitted proposals in the second round. Its proposal is for the EM2, a modified version of its Gas-Turbine Modular Helium Reactor (GT-MHR) design.

The EM2 employs a 500 MWt, 265 MWe helium-cooled fast-neutron high-temperature reactor operating at 850°C. This would be factory manufactured and transported to the plant site by truck. According to GA, the EM2 reactor would be fuelled with 20 tonnes of used PWR fuel or depleted uranium, plus 22 tonnes of uranium enriched to about 12% U-235 as the starter.

It is designed to operate for 30 years without requiring refuelling, the company said. Used fuel from the EM2 could be processed to remove fission products (about 4 tonnes) and the balance then recycled as fuel for subsequent cycles, each time topped up with four tonnes of used PWR fuel. The module also incorporates a truck-transportable high-speed gas turbine generator.

General Atomics has been the primary developer of modular helium-cooled nuclear power reactor systems, while its TRIGA research reactors have operated around the world for over 45 years. GA has teamed up with Chicago Bridge & Iron, Mitsubishi Heavy Industries and Idaho National Laboratory to develop the EM2.

Senior vice president of GA's energy and advanced concepts group John Parmentola commented, "We welcome the opportunity to join the Department of Energy in advancing the next generation of nuclear technology for reliable and cost-effective clean energy, for this century and beyond."

In November 2012, the Babcock & Wilcox (B&W) mPower reactor was selected as the winner of the first round of funding, receiving access to $79 million to commercially demonstrate the design by 2022. A second round of funding was announced in March 2013. The DoE anticipates awarding those funds by mid-January 2014. The maximum amount available in each of the first and second rounds is set at $226 million. More

 

Big nuke company decides renewables are a better bet in the U.S.

The world’s largest operator of nuclear power plants is dumping its stake in American reactors, turning its focus instead to wind and solar power.

EDF is selling its stake in Calvert
Cliffs Nuclear Power Plant in Maryland.

French utility company EDF announced this week that it will sell its stake in Constellation Energy Nuclear Group (CENG), which operates five nuclear reactors in New York and Maryland.

EDF cited cheap power produced by fracked natural gas as the big reason why it’s abandoning its American nuclear facilities. But the company said it will now focus its American business strategy not on fossil fuels but on renewable energy. From Reuters:

“Circumstances for the development of nuclear in the U.S. are not favorable at the moment,” [EDF Chief Executive Henri] Proglio said.

International Energy Agency analyst Dennis Volk said CENG’s eastern U.S. power plants were located in some of the most competitive power markets in the country, with high price competition, growing wind capacity and cheap gas.

“It is simply not easy to invest in nuclear and recover your money there,” Volk said.

Proglio said EDF would now focus on renewable energy in the United States. EDF employs 860 people in U.S. solar and wind, and since 2010 its generating capacity has doubled to 2.3 gigawatts. It manages another 7 gigawatts for other companies.

The French utility’s pullout comes as nuclear power plants shutter in California, Florida, and Wisconsin. The price of operating nuclear power plants has risen as the plants have grown older. Hopes of nuclear power being “too cheap to meter” were long ago dashed.

Mark Cooper, a senior fellow at the Vermont Law School’s Institute for Energy and the Environment, recently published a 40-page obituary [PDF] for the nuclear industry. From an article published a couple of weeks ago in The Plain Dealer:

Cooper, who thinks nuclear energy’s cost overruns and frequent shutdowns have always made it more expensive than it appears, recommends that the industry develop an orderly closing plan over the next few years, avoiding the rate chaos that unplanned closings might create.

“In 2013, more (nuclear) capacity retired early than in any year of the U.S. commercial nuclear sector,” he said in a press briefing. “In recent months, four reactors have been closed in early retirement, five major up-rates (increases in generating capacity) were cancelled.

“The bottom line is that the tough times the nuclear power industry faces today are only going to get tougher. Over three dozen reactors in almost two dozen states are at risk of early retirement. And a dozen face the greatest risk of being shut down,” he said.

Still, we won’t be rid of nuclear energy any time soon. About 100 reactors are still operating around the country, and two more are being built at an existing plant is in Georgia.

And even closing down retired nuclear power plants is a long and costly affair. The shutdown and cleanup at the Kewaunee plant in Wisconsin could cost $1 billion and take more than 50 years. More

 

Take Action at Fukushima: An Open Letter to Secretary General Ban Ki-moon

Dear Secretary General Ban Ki-moon:

You no doubt observed the Fukushima disaster on March 11, 2011, with terror and worry: what would another nuclear disaster mean for state relations, especially in your home region of East Asia? Fortunately, it seemed, the effects were largely kept to Japan’s islands and were less than many experts anticipated. Within weeks the stories dissipated if not disappeared from the major media outlets, only to be resurrected with personal interest stories of a hero or an especially tragic case of a lost loved one.

But the crisis is not over. Today, Martin Fackler reported in the New York Times that radioactively polluted water is leaking out of the plants and that the site is in a new state of emergency. Mitsuhei Murata, Japan’s former ambassador to Switzerland, wrote a letter last year that brought international attention to the thousands of radioactive spent fuel rods at the site and the danger their vulnerability presents; he has testified to this several times before Japan’s parliament. International experts, independent and of the International Atomic Energy Agency, have commented that the Tokyo Electric Power Company’s plans for the removal of the rods from the site and their storage in a safer, if still temporary, location are optimistic if not unrealistic.

The news media has done an adequate if meager job of reporting the many issues the fuel rods present. The radioactive fuel must be continuously cooled in order to stay safe; the improvised electric system that maintains this cooling has failed several times, once for more than 24 hours, both on its own and because of hungry rats. The mechanism that stands between safety and a fire at the Fukushima Daiichi plant is, to say the least, precarious. (And, as has been clear to many since the beginning, TEPCO hope to shirk its responsibility: first, in its safety and maintenance of the site; second, in paying its costs to Japan.)

One can only speculate to the extent of the consequences of a spent fuel fire, but, unarguably, once a fire ignites (from lack of cooling water or from an earthquake-caused spill), even the best case scenario would be an unprecedented global disaster. Possible consequences are the evacuation of Tokyo’s 35 million people, permanent disuse of Japan’s land, and poisoned food crops in the United States. These are not fantastic projections, but reasonable, if not conservative, expectations.

Yet, unimaginably but all too familiarly, the situation is still relegated to the back pages of our papers, and thus to the back of our leaders’ minds. This reminds me of our international approach to solving climate change, which I have partaken in for decades, first in the United Nations and then as the Secretary General of the Parliamentary Earth Summit in Rio de Janeiro: we have a latent but very serious issue that we can likely fix but lack the resolve and political will to do so. As you well know, a successful climate change agreement has eluded us.

In comparison with climate change, however, the radioactive fuel rod issue at Fukushima is both easier to solve and more urgent. Any Japanese can tell you another serious earthquake will hit Japan well inside the next decade. That is to say, this situation must be resolved quickly.

Still, even if possible to solve, the issue needs constant attention and competent and well funded actors. So who might take charge? The International Atomic Energy Agency said last week that it will take TEPCO 40 years to secure the radioactive fuel rods in more appropriate storage containers. TEPCO is already refusing to pay Japan billions of Yen in cleanup costs, and does not have the technology or wherewithal to perform the task competently and expediently. Yet, so far the Japanese government has only looked to TEPCO.

The next obvious choice outside Japan is the United States, for their technological superiority, money, and leadership. Early after the accident, the U.S. Department of Defense offered assistance to Japan, but the Japanese denied their help. It remains to be seen whether that door has permanently closed. This would not be a benevolent action: the U.S. sits in harm’s way in the case of a fuel pool fire; residents of California, Oregon, and Washington have already received much radiation. U.S.-led action, except perhaps by Oregon Senator Ron Wyden, is unlikely: U.S. senators and representatives continues to demonstrate their impotence at home or abroad.

I have long been advocating for an international team of independent experts to investigate the situation. The United Nations is one appropriate body to assemble and deliver such a team. The IAEA, however, should not take on the responsibility.

The IAEA’s mission is to promote the peaceful use of nuclear energy. Concerns of proliferation are not applicable here, and the disaster itself has certainly called into question (again) what the peaceful use of nuclear energy means and whether it should be promoted. While the agency has recently urged safety improvements at Fukushima, the official line of thinking is still, incorrectly and impossibly, to use TEPCO to carry out the process.

We are not only waiting for a bigger disaster. One is already unfolding before us. The health consequences of the released radiation are large: despite what major news outlets are reporting, we will see a significant jump in thyroid and other cancers in Japan in four to five years. Congenital malformations will likely begin to appear. The premature reporting of some UN agencies and the press at large has been irresponsible: do we have no notion of what “precaution” means? These latent effects will cripple much of Japan’s young population within the decade.
Our myopia, in Japan and internationally, is tragic. One bright spot was the UN Special Rapporteur Anand Grover’s fact-finding mission in Japan last year; I hope you back his findings and circulate them widely.

We have already waited too long, as we did for climate change, to take international action on Fukushima. But now it is clear that we cannot allow Japan to take care of an issue that could affect all of us.

Secretary General Ban Ki-moon, I urge you to use your unique position as the head of the United Nations to galvanize political will and organize an independent assessment team of international scientists and engineers to solve the Fukushima radioactive spent fuel rod issue before we are forced to reckon with the fallout of another disaster. Japan and the world should not have to suffer more because we choose to wait.

Yours truly,

Akio Matsumura

-Former Special Advisor to the United Nations Development Program
-Founder and Secretary General of the Global Forum of Spiritual and Parliamentary Leaders for Human Survival
-Secretary General of the 1992 Parliamentary Earth Summit Conference in Rio de Janeiro More

 

 

Ex-Regulator Says Reactors Are Flawed

WASHINGTON — All 104 nuclear power reactors now in operation in the United States have a safety problem that cannot be fixed and they should be replaced with newer technology, the former chairman of the Nuclear Regulatory Commission said on Monday. Shutting them all down at once is not practical, he said, but he supports phasing them out rather than trying to extend their lives.

Nine Mile Point Unit 1, New York, November 1969

The position of the former chairman, Gregory B. Jaczko, is not unusual in that various anti-nuclear groups take the same stance. But it is highly unusual for a former head of the nuclear commission to so bluntly criticize an industry whose safety he was previously in charge of ensuring.

Asked why he did not make these points when he was chairman, Dr. Jaczko said in an interview after his remarks, “I didn’t really come to it until recently.”

“I was just thinking about the issues more, and watching as the industry and the regulators and the whole nuclear safety community continues to try to figure out how to address these very, very difficult problems,” which were made more evident by the 2011 Fukushima nuclear accident in Japan, he said. “Continuing to put Band-Aid on Band-Aid is not going to fix the problem.”

Dr. Jaczko made his remarks at the Carnegie International Nuclear Policy Conference in Washington in a session about the Fukushima accident. Dr. Jaczko said that many American reactors that had received permission from the nuclear commission to operate for 20 years beyond their initial 40-year licenses probably would not last that long. He also rejected as unfeasible changes proposed by the commission that would allow reactor owners to apply for a second 20-year extension, meaning that some reactors would run for a total of 80 years.

Dr. Jaczko cited a well-known characteristic of nuclear reactor fuel to continue to generate copious amounts of heat after a chain reaction is shut down. That “decay heat” is what led to the Fukushima meltdowns. The solution, he said, was probably smaller reactors in which the heat could not push the temperature to the fuel’s melting point.

The nuclear industry disagreed with Dr. Jaczko’s assessment. “U.S. nuclear energy facilities are operating safely,” said Marvin S. Fertel, the president and chief executive of the Nuclear Energy Institute, the industry’s trade association. “That was the case prior to Greg Jaczko’s tenure as Nuclear Regulatory Commission chairman. It was the case during his tenure as N.R.C. chairman, as acknowledged by the N.R.C.’s special Fukushima response task force and evidenced by a multitude of safety and performance indicators. It is still the case today.”