Japan Nuclear Crisis of 2011

Ashley Seni
March 22, 2012

Submitted as coursework for Physics 241, Stanford University, Winter 2011


On March 11th, 2011, a magnitude 9.0 earthquake and its resulting tsunami devastated Japan, generating a major nuclear crisis at the Tokyo Electric Power Company (TEPCO)-operated Fukushima Daichii power plant. The plant suffered from several accidents that led to nuclear meltdowns in three reactors, including failure of the cooling systems and backup generators, reactor explosions, and damage to the fuel cores. [1] Immediately after the earthquake struck, the vibrations activated an emergency response at fifteen nuclear power plants in which control rods were automatically inserted into the reactors to terminate the nuclear fission reaction. [1] This response led to power failures across the country and especially affected the Fukushima Daichii plant, which requires an external source of electricity to operate cooling systems for their reactors. [1] Despite having backup generators in place to carry out the cooling function in an emergency, the tsunami destroyed the diesel fuel tanks for the generators. [1] In a desperate effort to cool the reactors and avoid reactor meltdown, the reactors were flooded with seawater mixed with boric acid to hinder the decay of the uranium fuel. [1,2] Plant workers vented the reactors to accommodate the hydrogen and steam pressure that resulted from overheating; however, this venting set off explosions. [2] Furthermore, the initial emergency response that shut down the reactors led to damage to the fuel cores. Although the fission reaction in the reactors was suspended, the fuel continued to decay, producing heat that eventually caused the fuel rods to melt. [1] As fuel rods melt, they release large amounts of radiation and pose significant health and environmental risks. [2] There are many challenges associated with Japan's ongoing response to the events at the Fukushima Daichii power plant. It is necessary to look at the country's history with nuclear energy to discern various strategies for controlling the 2011 nuclear crisis and coping with its effects.

History of Japan's Nuclear Energy Program

The Japanese Atomic Energy Commission (JAEC) was established in 1956 to advance the country's goal of achieving energy-independence. The progress of their efforts was evident in 2007 when Japan operated 55 nuclear reactors, which supplied approximately 33% of the country's electricity supply. [3] The JAEC proposed a policy that would close the nuclear fuel cycle and would help reduce the country's dependence on foreign resources. They specified that spent fuel from light water reactors would be reprocessed and the reprocessed material, plutonium, would be used in mixed uranium-oxide fuel for new fast breeder reactors (FBR). [4] This policy was limited, however, by security and proliferation concerns as plutonium is a material used to develop nuclear weapons. Developing FBR technology would entail excess plutonium, which would in turn have serious implications for the country's position in the worldwide nuclear energy field.

The government acknowledged the ramifications of this policy and held roundtable conferences to increase transparency between the government, industry, and public on the Japanese nuclear program, to address concerns regarding security, waste management, safety, etc., and to obtain feedback on their program. [4] These conferences had useful results for the JAEC in developing a consensus on the country's nuclear energy policy. One of the conferences made the following conclusions: spent fuel should be reprocessed domestically and stored away from the reactor-site, FBR technology should continue to be developed, the use of plutonium must be further understood, research results should be shared with the public and international community, and nuclear safety should be a main priority. [4]

The Japanese nuclear energy industry has experienced a number of accidents and oversights that have tested the strength of their energy policy. In 2007, Japan experienced a magnitude 6.8 earthquake that caused a shut down of the TEPCO-operated Kashiwazaki-Kariwa plant, which was later found to have been built above an active fault line. [3] TEPCO failed to disseminate information regarding the incident in a timely manner and understated some of the amount of waste and leaks that had occurred. [3] This event resulted in new guidelines to re-evaluate nuclear power plants and their quake resistance. [3] They improved geomorphological techniques to estimate and measure the movements of faults and ground shaking, although they failed to address the issue of "blind thrusts," which cannot be detected by seismologists, but are capable of causing earthquakes of magnitude 6.5+. [3] In addition, the Nuclear Safety Commission recommended that all power plants have full-time fire fighters and a reliable communication system to contact outside emergency services. [5]

Challenges and Opportunities in Controlling the Nuclear Crisis

Various factors confirm that the Fukushima Daichii plant was not prepared for a disaster of this magnitude. Specifically, the fuel tanks for the backup generators were positioned at ground level and extremely vulnerable to external environmental damage. The walls surrounding the nuclear plant were built to withstand a tsunami of 18 feet and were therefore overcome by the 22-foot tsunami, despite recommendations to construct a defense that could protect against a tsunami of at least 20 feet. [5] TEPCO did not learn from its experience in 2007 and did not heed the suggestions of the Nuclear Safety Commission to have full-time fire fighters. The plant workers had to put out blazes themselves with limited resources. Furthermore, TEPCO had carried out an underwater survey in 2007 to assess the Fukushima Daichii plant's susceptibility to earthquakes, which should have revealed a need for measures to improve the plant's resistance to earthquakes. TEPCO's lack of foresight with regards to the design and organization of the Fukushima Daichii power plant prevented workers from being able to optimize their emergency response efforts.

The way in which the Japanese government copes with these challenges presents opportunities for preventing a similarly severe crisis in the future. The government needs to enforce higher nuclear plant standards, as well as implement more stringent safety requirements for building nuclear plants. This includes installing improved passive safety systems that can still operate without an external power source. Additionally, building standards must overestimate the effects of potential natural disasters; as of 2007, power plants were required to resist a magnitude 6.5 earthquake. Moreover, industry players, such as TEPCO, should be audited to ensure that they uphold sound practices and operate power plants in the safest, most secure way possible. Another important aspect that needs to be addressed is transparency. The transparency amongst the government, industry, and public was a major strength of Japan's nuclear energy policy. It appears to have become less important recently as TEPCO did not immediately release information about the condition of the power plants within an appropriate time frame to the public and international community. This transparency is extremely important, as those who are directly affected by the nuclear crisis must have a complete understanding of the circumstances.

Conclusion: Implications for Japan's Energy Future

Unless the government addresses these concerns and regains the trust of those most affected by potential nuclear crises, its citizens, their nuclear energy policy will not advance. The Japanese government, the JAEC, and related energy committees need to shift their focus from energy-independence to safety. One consideration is that the Japanese government focus its energy policy on alternative forms of energy. Also, the government must enforce improved safety standards. A significant amount of work is needed to evaluate the safety and security of nuclear energy and the numerous health and environmental concerns in Japan in the coming years.

© Ashley Seni. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] R. Gray, "Japan Earthquake: How the Nuclear Crisis Unfolded," The Telegraph, 20 Mar 11.

[2] H, Tabuchi and M. L. Wald, "Japanese Scramble to Avert Meltdowns as Nuclear Crisis Deepens after Quake," New York Times, 12 Mar 11.

[3] D. Cyranoski, "Quake Shuts World's Largest Nuclear Plant," Nature 448, 392 (2007).

[4] S. E. Pickett, "Japan's Nuclear Energy Policy: From Firm Commitment to Difficult Dilemma Addressing Growing Stocks of Plutonium, Program Delays, Domestic Opposition and International Pressure," Energy Policy 30, 1337 (2002).

[5] R. Gray and M. Fitzpatrick, "Japan Nuclear Crisis: Tsunami Study Showed Fukushima Plant Was at Risk," The Telegraph, 19 Mar 11.