Learning from a Disaster: Improving Nuclear Safety and Security after Fukushima
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Learning from a Disaster: Improving Nuclear Safety and Security after Fukushima
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Overview
It explains the complex interactions between nuclear safety risks (the causes and consequences of accidents) and nuclear security risks (the causes and consequences of sabotage or terrorist attacks), exposing the possible vulnerabilities all countries may have if they fail to learn from this accident.
The book further analyzes the lessons of Fukushima in comparative perspective, focusing on the politics of safety and emergency preparedness. It first compares the different policies and procedures adopted by various nuclear facilities in Japan and then discusses the lessons learned—and not learned—after major nuclear accidents and incidents in other countries in the past. The book's editors conclude that learning lessons across nations has proven to be very difficult, and they propose new policies to improve global learning after nuclear accidents or attacks.
Product Details
| ISBN-13: | 9780804797351 |
|---|---|
| Publisher: | Stanford University Press |
| Publication date: | 04/06/2016 |
| Pages: | 232 |
| Product dimensions: | 5.90(w) x 8.90(h) x 0.90(d) |
About the Author
Read an Excerpt
Learning from a Disaster
Improving Nuclear Safety and Security After Fukushima
By Edward D. Blandford, Scott D. Sagan
STANFORD UNIVERSITY PRESS
Copyright © 2016 Board of Trustees of the Leland Stanford Junior UniversityAll rights reserved.
ISBN: 978-0-8047-9735-1
CHAPTER 1
Japan's Fukushima Nuclear Disaster: An Overview
Kenji E. Kushida
The Tohoku earthquake that struck off the northeastern coast of Japan on March 11, 2011, had a magnitude of 9.0, the world's fourth largest in modern recorded history. The island of Honshu moved 2.4 meters to the east. A massive tsunami followed shortly thereafter, reaching an estimated height of over 30 meters in some places. A 500-kilometer section of Japan's northeastern coast was devastated, with a death toll of more than 15,000 people. Damage from the earthquake and tsunami led to one of the world's most serious nuclear disasters, at the Fukushima Daiichi (number one) Nuclear Power Station on Japan's eastern coast, owned and operated by the Tokyo Electric Power Company (TEPCO).
The Fukushima Daiichi plant had six nuclear reactors, three of which were in operation at the time of the earthquake and tsunami, with the rest undergoing routine maintenance. As the earthquake hit, the active reactors were successfully scrammed (that is, placed under emergency shutdown). All off-site power from the external power grid was lost as a result of severed power lines and earthquake damage to transformer stations, but the on-site emergency backup power sources, consisting of diesel generators and batteries, immediately came online to operate the cooling pumps and other functions.
The tsunami hit the plant approximately forty minutes later, reaching a height of over 12 meters. It well exceeded the maximum safety design of 5.7 meters and obliterated the 10-meter-high seawall. The tsunami destroyed almost all on-site backup power sources, as well as most of the pumps necessary to cool the reactors. Over the next three days, despite desperate attempts on the ground to restore cooling, the three reactors that had been active before the earthquake experienced fuel core meltdowns, and hydrogen explosions blew away the roofs, walls, and upper floors of three reactor buildings.
Although the catastrophe at Fukushima Daiichi emitted at least 168 times the amount of radioactive cesium 137 as the Hiroshima atomic bomb, there were no direct deaths from radiation exposure. A mandatory evacuation zone with a radius of 10 kilometers was imposed in the early hours of March 12, expanded to 20 kilometers later that day, displacing more than eighty thousand residents. The disaster was eventually declared level 7 on the International Nuclear Event Scale (INES) — the maximum level on that scale. Chernobyl was the only other level 7 nuclear accident to date, although it released approximately six times the amount of radioactive material as Fukushima, since it was an explosion of the core reactor during active operation. At Fukushima, sea water pumped into the reactors and used fuel storage pools created more than 100,000 tons of contaminated water, about a tenth of which had been released into the ocean, by the end of 2011.
The following account of Japan's nuclear disaster is based on a variety of sources and studies published after the disaster. It is designed as an overview, presenting the basic facts about the disaster to set up subsequent chapters. Readers interested in further technical details and analyses about the causes of the accident, such as failures at the level of plant design, emergency preparedness, Japan's nuclear energy and electricity industry governance structures, and broader social, cultural, and political factors can refer to the reports themselves. The most reliable and extensive reports include the following: an accident report compiled by a government committee; an independent commission convened by the National Diet; private sector independent accident investigation commissions and projects; TEPCO's own report; reports from international organizations such as the International Atomic Energy Agency (IAEA) and other regulatory and industry bodies including the Institute of Nuclear Power Operators (INPO); numerous credible accounts by investigative journalists; works by academics and independent nuclear experts; and accounts by some political leaders. Most reports and accounts draw from extensive interviews, many of which are publicly available. The author also interviewed several experts involved in writing the independent reports.
Unless otherwise noted, factual information in this chapter relies on investigation commission reports where they are duplicated and are therefore considered common knowledge.
THE DISASTER AS IT UNFOLDED
The nuclear accident ensued from the combination of two natural disasters: the earthquake and the tsunami it caused. Each brought a different type of destruction, and although four nuclear power plants along Japan's northeastern coast were struck by the March 11 earthquake and tsunami, the combination of damage at Fukushima Daiichi was catastrophic.
The Earthquake
The magnitude 9.0 earthquake occurred at 2:46 p.m. on March 11, 2011. The quake itself caused major damage at the Fukushima Daiichi nuclear plant, much of which was more than forty years old. In particular, most of the operations center buildings were catastrophically damaged, to the point of becoming unusable. The earthquake severed all external power lines to Fukushima Daiichi, making it completely dependent on its on-site backup power sources.
After the earthquake hit, staff at the Fukushima Daiichi operations headquarters quickly evacuated to a newly constructed emergency operations center, built on slightly higher ground and designed to withstand strong earthquakes. Had this structure not existed, the lack of a viable on-site staging ground for the rescue operation would have likely led to a significantly worse outcome. This seismically reinforced operations center had been completed just eight months prior to the earthquake.
The Tsunami: Devastating Excess and Critical Deficiency of Water
The tsunami hit in multiple waves, starting at 3:27 p.m., forty minutes after the earthquake. The second wave, which hit at 3:35 p.m., was higher, exceeding 12 meters at the site of the Fukushima Daiichi plant. It obliterated the 10-meter-high concrete seawall designed to stop a tsunami of only up to 5.7 meters. The tsunami destroyed much of the cooling system, largely consisting of pumps responsible for pumping seawater into the reactor building to cool the fuel rods. Critically, it also irreparably damaged almost all of the on-site backup power sources and infrastructure — the diesel generators, batteries, and circuit boards for the plant. The plant had lost the capability to cool the reactors.
The need for massive quantities of water for nuclear reactors cannot be exaggerated. The Fukushima Daiichi Reactors 1, 2, and 3, which were operating at the time of the disaster, were boiling water reactors (BWR). In a BWR, heat from the nuclear reactions of fuel rods within a sealed chamber boils water under high pressure, creating steam that rotates turbines to generate electricity. The primary, or first-stage, cooling system for the Fukushima reactors required 5,600 tons, 7,570 tons, and 7,760 tons of seawater, respectively, per hour during normal operations. An additional 20 tons of seawater per second, or 1.7 million tons per day, were required to cool the steam and convert it back to water. Therefore, the total seawater requirement was almost 1.9 million tons daily for this one plant.
In the Fukushima Daiichi plant, the initial scrams — emergency shutdowns of the fuel core reactions — as the earthquake hit were successful. However, even after shutting down, the fuel rods retained considerable heat, requiring large amounts of water for cooling. The three reactors combined required approximately 70 tons of water per hour for ten days, even after shutting down, to avoid a catastrophe. Restoring cooling capabilities was of paramount importance. Yet, with the complete loss of off-site power as well as on-site backup power, along with damage to most of the cooling systems, the plant faced an acute crisis.
At 4:30 p.m. on March 11, when it had become clear that emergency teams had not been able to cool the reactors and could not monitor the water levels of Reactors 1 and 2, Fukushima Daiichi plant manager Masao Yoshida officially declared a "nuclear emergency in progress," in accordance with the Nuclear Emergency Preparedness Act. As soon as the hot core evaporated the water and exposed the fuel rods, the rods would overheat and become damaged, resulting in the phenomenon commonly labeled "meltdown."
At 7:00 p.m., the prime minister's office declared a nuclear emergency to the nation. At 8:50 p.m., around four and a half hours after the nuclear emergency had been declared by the Fukushima Daiichi plant, the Fukushima prefectural government announced that residents within a 2-kilometer radius of the Fukushima Daiichi plant should evacuate. Half an hour later, at 9:23 p.m., the central government announced a 3-kilometer radius for evacuation, ordering people to stay indoors within a radius between 3 and 10 kilometers. It was later determined that Reactor 1's core had already been exposed by around 5:00 p.m. and that increased radiation levels were detected by 5:50 p.m. in the plant.
Early Information and Communication Difficulties
As events rapidly unfolded, severe information and communications problems at all levels of decision-making plagued the recovery effort. The earthquake paralyzed telecommunications networks around the country, and in the Tokyo metropolitan area all public transportation shut down, airports were closed, and roads quickly become severely gridlocked. In the Tohoku region, many of the roads were severely damaged, with the tsunami ravaging coastal areas.
Organizationally, the locus of emergency decision-making became unclear as the nuclear crisis at Fukushima Daiichi developed. The Japanese legal framework stipulated that the power operator was in charge. However, during this initial time of crisis, neither TEPCO's chairman nor its president were at TEPCO headquarters. With the transportation infrastructure such as airports, trains, and freeways shut down, and with roads in gridlock, it took both TEPCO's chairman and president more than seventeen hours to return to headquarters, by which time the meltdowns at Daiichi had already occurred. Since telecommunications networks were down following the earthquake, it is unclear how effectively the chairman and president could communicate effectively with TEPCO headquarters, let alone the Daiichi plant operations center. The prime minister's office, overseeing the response to the broader disaster, was not aware of the leadership vacuum at TEPCO, breeding severe mistrust on the part of Prime Minister Kan Naoto. Concerned by the lack of effective communication from TEPCO, he became personally involved in the rescue effort at Daiichi.
The prime minister's office itself suffered communications problems. The government's underground emergency operations headquarters, designed for use during a terrorist attack or national conflict, lacked cellular service as a security measure. This frustrated the prime minister's attempts to orchestrate the recovery effort, leading him to move his operations up to his personal office on the fifth floor. However, his office lacked emergency telephone and fax lines, resulting in aides running up and down six flights of stairs to deliver emergency messages. The Nuclear Safety Commission (NSC) and Nuclear and Industrial Safety Agency (NISA), an agency under the Ministry of Economy, Trade, and Industry, set up a nuclear emergency headquarters within the prime minister's office, but there was no permanent or previously designated location at which it was to be set up. The office ended up being a small room in a mezzanine between the ground floor and basement emergency headquarters. The room had only one phone line, and initially no computer, fax, or information such as schematics of the Fukushima nuclear plant. With limited access to information, the head of NISA, whose function was to advise the prime minister, ended up relying on his memory of the various reactor configurations and plant layout at Daiichi. Both he and the prime minister learned of the hydrogen explosions via television during a meeting in which the head of NISA was reporting the latest — clearly outdated — information to the prime minister.
According to the law, the locus of information flows on the ground at Fukushima Daiichi should have been an off-site emergency operations center about 5 kilometers from the plant. However, transportation and communications paralysis, combined with the power outage, rendered the off-site center inoperable. Even at midnight on March 11, when a Ministry of Economy, Trade, and Industry (METI) vice minister arrived via helicopter from Tokyo, the building was still dark and unusable, although it was the designated clearinghouse for managing information flows among the plant, the government, TEPCO, and local municipalities, as well as for orchestrating evacuations.
Within the Fukushima Daiichi plant itself, the loss of nearby cellular towers limited the ability to stage rescue operations, leaving the plant manager in charge, Yoshida, to work with limited information. With control panel indicators and sensors damaged in unpredictable ways, and with the plant itself lacking electricity, assessing the status of reactors required the time-consuming and potentially risky process of workers physically entering the reactor buildings and reporting back to the operations center with information.
Initial Recovery Efforts: The Direct Line and Race to Provide Electricity
Key initial recovery efforts at the stricken Daiichi plant included the creation of a direct line from which to inject water and a race to provide electricity to the plant.
Very early on in the crisis, plant manager Yoshida sent teams of men into the reactor buildings to manually open the valves to create a direct line for injecting water into the reactor. Although plant operators could normally push a button in the operations center to open valves, teams had to open multiple large valves manually within the reactor buildings in the absence of electricity. As radiation levels spiked within the reactor buildings by the late evening of March 11, the areas where the valves were located were deemed too dangerous to access. Therefore, having opened the valves in the late afternoon was critical in stabilizing the reactors later on by injecting water.
Also in the late afternoon of March 11, hours before issuing the evacuation order, Prime Minister Kan had begun to involve himself personally in the recovery effort. He directly orchestrated the dispatching of battery trucks from the Self-Defense Forces (SDF) — Japan's equivalent of a military, limited to defensive capabilities — to the plant to provide electricity for the cooling systems.
By 11:50 p.m. the power trucks had yet to be connected, because of the gridlocked traffic near the Tokyo metropolitan area, damaged roads in the Tohoku region, and technical compatibility issues, including difficulty connecting the first set of SDF battery trucks to the remaining emergency cooling system pumps owing to differences in voltage and incompatible connectors. At this time, the Fukushima Daiichi plant issued another report: radiation levels within the reactor building were rising, indicating a radiation leak. Until this time the working assumption at the plant has been that the emergency cooling system for Reactor 1 was in operation. However, it turned out that the instrument panel indicating sufficient water levels was unreliable. Water levels were low, and the exposed fuel core had damaged the containment vessel, leading to radiation leakage.
Venting the Reactor Buildings
The next step in the recovery effort was to reduce pressure within the pressure containment vessel. Around 11:50 p.m., workers at Fukushima Daiichi discovered that the pressure containment vessel in Reactor 1 had reached an internal pressure of 600 kilopascals (kPa), well exceeding its maximum design of 427 kPa. "Venting" — the process of releasing hot air from the containment vessel itself into the atmosphere in order to lower the reactor pressure and temperature — was deemed the only option, both to prevent a breach of the containment vessel, and to enable water to be injected directly into the reactor. The design of the Fukushima Daiichi reactors, lacking filters to reduce the amount of radioactive material released in the event of venting, meant that venting would release substantial radioactive material into the atmosphere.
(Continues...)
Excerpted from Learning from a Disaster by Edward D. Blandford, Scott D. Sagan. Copyright © 2016 Board of Trustees of the Leland Stanford Junior University. Excerpted by permission of STANFORD UNIVERSITY PRESS.
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Table of Contents
Acknowledgments vii
Contributors ix
Part I The Fukushima Accident
Introduction: Learning from a Man-made Disaster Scott D. Sagan 3
1 Japan's Fukushima Nuclear Disaster: An Overview Kenji E. Kushida 10
Part II Learning Lessons from Fukushima
2 The Accident That Could Never Happen: Deluded by a Design Basis Gregory D. Wyss 29
3 Security Implications of the Fukushima Accident Kaoru Naito 58
4 Political Leadership in Nuclear Emergency: Institutional and Structural Constraints Nobumasa Akiyama 80
5 Radiation Protection by Numbers: Another "Man-made" Disaster Toshihiro Higuchi 109
6 Encouraging Transnational Organizational Learning Kazuto Suzuki 136
Part III Lessons Learned about Lessons Learned
7 Were Japan's Nuclear Plants Uniquely Vulnerable? Phillip Lipscy Kenji E. Kushida Trevor Incerti 157
8 Beyond Fukushima: Enhancing Nuclear Safety and Security in the Twenty-first Century Edward D. Blandford Michael M. May 183
Index 207