Better design before the March 2011 Fukushima Daiichi nuclear plant disaster and better communication after could have softened its horrifying impact, a report issued in July from the National Academy of Sciences concluded.
Instead, about 80,000 people had to be evacuated, the economic toll topped $250 billion (U.S.), and Japan shut down all nuclear power — which it’s only now restarting.
B. John Garrick, a nuclear engineer and vice chair of the Nuclear Regulatory Commission’s Committee for Improving Safety and Security of U.S. Nuclear Plants, outlined the report’s findings and recounted what he saw at Fukushima for an audience of Vanderbilt University School of Engineering professors and students on Tuesday.
David Kosson, the Cornelius Vanderbilt Professor of Engineering in the Department of Civil and Environmental Engineering, introduced Garrick as the “father of modern-day risk assessment.” Garrick also investigated space shuttle risks after the 1986 Challenger explosion.
For his presentation, Garrick described a series of emergency cooling system failures and related hydrogen explosions across the six units. An earthquake affected the site first, but the overriding cause of the disaster was flooding, he said. The resulting tsunami hit the coast at 13 meters above sea level, but emergency generators sat only 2 meters above sea level and the reactor buildings 10 meters above.
“A tsunami like this hadn’t hit in 1,000 years,” Garrick said. “But 1,000 years in the nuclear world is a high-frequency event.”
With the loss of AC and DC power, the failure of emergency cooling systems and the quick degradation of the nuclear material, disaster was unavoidable. “It was not our job to find fault,” Garrick said of his committee’s work. “Our conclusion is that they did an amazing job, given the circumstances.”
But lessons for the U.S. include emergency staffing levels that take into account events that last for days and weeks, not hours, he said. Experts here also must consider risk assessments in terms of whole sites, not individual units, since incidents in some Fukushima reactors triggered problems in others.
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Heidi Hall, (615) 322-6614
Heidi.Hall@Vanderbilt.edu
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