The disaster at the Fukushima Daiichi plant in Japan has remained an important topic in the industry and has provided an opportunity to learn about performance procedure modifications since the magnitude 9.0 earthquake and tsunami damaged the plant in early March. Brian Erler, with Erler Engineering, said the accident, though, was more than just a nuclear issue.
“This was a natural disaster” said Erler. “And it was devastating.”
As large as the earthquake was, though, the units 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.
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.
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.
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.
Masaki Morishita with the Japanese Atomic Energy Agency said the cost, to date, for the recovery due to the earthquake and tsunami has reached $220 billion.
Impact on U.S. Nuclear Plants
The United States has 24 operating boiling water reactors, which 23 of are of similar design to the five Mark 1 reactors at Fukushima Daiichi. The U.S. Nuclear Regulatory Commission (NRC) 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.
No nuclear power plants “in the U.S. pose an imminent risk” to public safety, said Elmo Collins, Regional 4 Adminstrator, NRC, during the annual POWER-GEN International Keynote session.
Some countries have already made the decision to end their nuclear programs, such as Germany and Italy.
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 continued with new nuclear projects.
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.
“A lot more has to be learned,” said Erler. “But the industry will more forward and respond to lessons learned.”