The most important issue being addressed at the 2011 American Nuclear Society (ANS) Annual Meeting are the events that have and are currently taking place at the Fukushima Daiichi nuclear power plant. Rightfully so. Over 20,000 people are either dead or missing and over 100,000 have been displaced from their homes following the events that took place after the 9.0 earthquake and massive tsunami. The amount of property damage is expected to be in the $300 billion range. Yet the nuclear crisis has been lead news globally since March 11. The earthquake and tsunami were devastating and the events at the Fukushima plant are hard to understand. It is very pre-mature to look at possible lessons learned until the industry knows exactly what went wrong.
As large as the earthquake was, though, the units that were operating at full power, Units 1, 2 and 3, shut down as they should have. The other three units, Units 4, 5 and 6, were in various stages of refueling. When the tsunami struck Units 1 though 4 the cooling systems were rendered inoperable. Hisashi Ninokata with the Tokyo Institute of Technology said that possible seismic damage to the piping systems and the complete structure may never been known due to the damage caused by the tsunami and hydrogen explosions onsite. Ninokata continued by saying that the earthquake caused the loss of offsite power at Fukushima and the damage “severely hampered recovery efforts.”
“Long-term station black out was not assumed in the hope that the offsite power would be recovered and diesel generators would be restored soon,” he said. “But it was not true.”
Joe Colvin, president of the American Nuclear Society, said there are many things that can be discussed and many conclusions that may be drawn about what exactly took place following the impact of the tsunami. But he did say, in his opinion, that the design basis for the facility was not adequate.
“The plant sustained a magnitude 9.0 earthquake, which was beyond its design basis of 8.2,” he added.
But the plant was designed for a tsunami of roughly 5.7 meters, which is about 19 feet. The actual tsunami triggered by the earthquake is believed to have been in the range of 48 feet tall.
“Clearly that is a significant impact difference,” said Colvin.
The design of the plant placed critical equipment, such as the diesel generators, below grade which caused the loss of that equipment when trying to bring the reactors to a safe shutdown.
“The elevation of some components was not appropriate to cope with the tsunami,” said Dr. Akira Omoto, Commissioner of the Japan Atomic Energy Commission.
This will be reviewed as the industry tries to understand the events.
In total, 14 nuclear power units along the coast of Japan were affected by the earthquake and tsunami. Both the Onagawa and the Tokai stations were safe from the looming disaster at Fukushima due to the height of these plants’ sites, added Omoto.
Still, Ninokata said that the area was never prepared for a 14 meter high tsunami, even with warnings of an impending tsunami. But the quick actions by the manager at the Fukushima Daini plant to distribute the only remaining power line to the unit at Daini without power saved this plant, too, from disaster.
Impact on U.S. Nuclear Plants
The United States has 24 operating boiling water reactors and 23 of these plants are of similar design to the Mark 1 reactors at Fukushima Daiichi. The U.S. Nuclear Regulatory Commission has launched a task force to perform both a short- and long-term review of all nuclear power plants in the U.S. Resident inspectors have been reviewing plants’ extensive mitigation guidelines, station black out, seismic and flooding issues, as well as severe accident management guidelines. Spent fuel storage pools have also been inspected at both operating and inactive facilities.
To date, the task force and resident inspectors have yet to find any issues that would undermine the confidence of the NRC in the continued safe operation and emergency preparedness of the U.S. plants, although the safety review is still in its early stage as is the investigation at Fukushima Daiichi. Michael Weber, deputy executive director for operations at the NRC, said they do expect the near term task force will recommend actions for the Commission’s consideration to enhance both safety and emergency preparedness.
“The Fukushima event has highlighted the challenges of coping with long-term station blackout and underscored the importance of mitigating its consequences,” said Weber.
He did add that if there are lessons to be learned from Japan that indicate the NRC needs to make improvements to the regulatory program, they will do so.
Still a Long Road Ahead
“The impact of the Fukushima event has led many, many countries, those involved in nuclear energy and those thinking about it, to reexamine the ongoing role of nuclear power in their country,” said Colvin.
Some countries have already made the decision to end their nuclear programs, such as Germany and Italy.
“I always find it fascinating that countries will hold votes for referendums before the facts are in,” said Dale Klein, former NRC Commissioner.
China will continue with its nuclear program to keep up with the large demand for electricity as the nation continues to grow. China did take a slight pause after the Fukushima events, “but have no choice than to continue” with nuclear energy, said Klein.
The global community outside of the nuclear industry will still be somewhat concerned with nuclear technology. It is up to the industry to educate the public so they can make an informed decision regarding the use of nuclear power.
Ironically, the units at Fukushima Daiichi were schedule for closure next year. The disaster has changed the landscape of nuclear power and as the industry attempts to move forward globally, they must adjust.
“We need to be thinking more broadly,” said Colvin. “We will probably learn lessons that will not only be applied to the technology now, but also the technologies that we look to in the future.”
As has been said multiple times, understanding what exactly took place at the Fukushima Daiichi nuclear power plant will take quite some time.
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