On the role of human error in the Fukushima nuclear accident.
It has been five years to the day since the 2011 Tohoku earthquake shook the coastline of Japan’s Honshu island, leading to the tsunami that killed over 15,000 people. Beyond this real disaster, this tsunami also caused a major accident at the Fukushima nuclear power plant, which displaced hundreds of thousands more. The magnitude 9.0 earthquake and resultant tsunami destroyed offsite and onsite power supply to the Fukushima Daiichi nuclear power station, causing the fuel of three reactors to melt and substantial amounts of radioactive material to be released out of the plant. The environmental and economic consequences of the Fukushima accident were significant. An estimated 200,000 Japanese were forced to relocate from their homes and their return awaits a massive land remediation effort that will take decades to complete.
The environmental and economic consequences of the Fukushima accident were significant.
Not surprisingly, much of the coverage of the incident tends to emphasize the resilience of Japanese society during the emergency and the fact that no individuals were killed immediately by the nuclear accident. The over 15,000 who were killed because the Japanese tsunami protection system did not warn or protect them all too often appear to be forgotten today. But these accounts overemphasize the role of good fortune over good planning and pessimists see the fact that the Fukushima accident did not produce massive fatalities in Japan as “homage to plain dumb luck.” The appropriate perspective on Fukushima must, however, include a basic awareness that the disaster could have easily been much worse in terms of loss of life and economic damage to Japan, and even surrounding countries. Equally, with modestly better advance preparation, none of the Fukushima reactors would have suffered any fuel damage. Due to a lack of preparation, the natural disaster of the 2011 earthquake set off a major man-made accident, caused by human error and institutional shortcomings, and from which we stand to learn many lessons in order to redouble efforts to improve nuclear safety.
The accident at Fukushima did not start on March 11, 2011, but decades earlier. The failings that led to the meltdown were the result of a number of organizational and safety culture pathologies. In technically deconstructing the accident at Fukushima, little about the event sequences that led to meltdown conditions were unknown to the nuclear industry. Within the nuclear industry it is well understood that the loss of both offsite and onsite power results in station blackout conditions, causing cooling systems to quit and nuclear fuel to overheat and effectively melt. But nuclear power stations are supposed to be designed to prevent such accidents from occurring in the first place—but that design process is vulnerable to miscalculation, overconfidence, and bad judgment on the part of institutional and individual actors.
The failings that led to the meltdown were the result of a number of organizational and safety culture pathologies.
As a rule, nuclear power plants are designed to maintain their integrity and performance of safety or security functions for a number of normal operational events as well as abnormal events that are expected to occur or might occur during the lifetime of the plant. In addition, they are designed to maintain performance of these functions for a set of what are known as design basis accidents—postulated threats and failures that a nuclear facility must be designed and built to withstand without loss to the systems, structures, and components necessary to assure public health and safety. Designing to the design basis does not by itself guarantee an effective response to the worst possible conditions. The Fukushima accident involved conditions that vastly exceeded the design basis, as evidenced by the drastically undersized seawall that surrounded the plant. The decision to store critical backup equipment and locate vital electrical components in areas of the plant that were susceptible to flooding was based on the notion that a tsunami wave large enough to compromise the seawall could not occur.
The international community has made great strides in absorbing the lessons learned from the Fukushima accident. In the United States, the nuclear industry has invested billions of dollars in plant improvements as well as the FLEX program which provides an additional layer of backup power after an extreme event by stationing vital emergency equipment in multiple locations. Internationally, there have been positive measures to strengthen organizations responsible for enhancing nuclear safety transnationally such as the World Association of Nuclear Operators (WANO) and the International Atomic Energy Agency (IAEA).
However, with all of these positive reforms changes, we are often reminded of the eternal vigilance and effective learning that is continually required to ensure the safe operation of nuclear power. Since the start of civilian nuclear power, there have been a number of learning opportunities—concerning both safety and security—that have served as opportunities to galvanize the nuclear industry. Many of the more significant accidents such as Three Mile Island, Chernobyl, and Fukushima have been deconstructed and through root cause investigations revealed there were numerous human errors that contributed to the accident and in some cases greatly exacerbated the consequences. Simply put, the job is never done.
Five years later, the Fukushima accident gives us a unique opportunity to reflect on possible lessons for enhancing nuclear operations and improving nuclear security. Nuclear safety and security share the common goal of ensuring the protection of local populations, public health, society at large, and the environment. And the potential application for such lessons is not only limited to nuclear accidents, but to intentional attacks on nuclear facilities as well. As of today, there have been no major security incidents that have resulted in a successful radiological sabotage of a civilian nuclear installation. However, the fact that such an event has not occurred should not be a cause for complacency, for we know that terrorists have scoped out nuclear facilities for potential sabotage or theft of materials, most recently in the case of the Paris ISIL terrorists whom we know were following a Belgian nuclear plant official presumably to get access to a nuclear facility for nefarious purposes.
The English translation of Fukushima is “good fortune island.” There was certainly no good fortune that led to the combined natural disasters and man-made disaster that occurred five years ago. However, one can hope that the lessons from the nuclear accident lead to demonstrably improved nuclear safety and security into the future. Within the nuclear industry, we have an obligation to learn from every opportunity—both positive and negative. Nuclear power can play a critical role in meeting future electricity demands while reducing anthropogenic emissions and reliance on fossil fuels. Let us hope that the real good fortune from Fukushima is that we can continue this learning process to forestall unknown future dangers.
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