Nearly six months after a devastating earthquake rocked a nuclear power plant in Japan, engineers say the design lessons are starting to come into sharper focus.
The good news from the event is that residents near the Fukushima Daiichi plant weren't exposed to high levels of radiation. The bad news is that some plant workers may have been exposed to higher levels, and the plant itself sustained serious damage. Three of its reactor cores probably ruptured, and cracks reportedly surfaced on the outside of the four-foot-thick concrete containment walls.
"There are two ways to look at it," James F. Stubbins, a professor of nuclear, plasma, and radiological engineering at the University of Illinois, told Design News. "You could say it's a once-in-400-year event, so maybe the actions of the designers could be understood. On the other hand, there could have been better preparation."
Experts interviewed by Design News cited several key areas of concern regarding the plant's design and the response that followed. The biggest, they said, was the placement of diesel generators and pumps. The tsunami that followed the earthquake wiped out both, disabling the plant's emergency cooling capabilities.
"They could have placed the diesel generators 100 feet up and they could have built the surrounding walls higher," said Jeff Terry, an assistant professor of physics at Illinois Institute of Technology. "The design just wasn't able to handle a 39-foot-high tsunami."
Experts also suggested that future plants might benefit by replacing aging reactors earlier and by shipping spent fuel away from the site. "We should take the waste and get it out of there," Terry said. "Odds are, nothing is going to happen. But I'd rather take those odds in an unpopulated area."
In retrospect, it also appears that plant officials could have reacted to the emergency more expeditiously. "There should have been more planning for events beyond their design specs," Stubbins told us. "They wasted a lot of time when they could have been pumping seawater. Management didn't want to ruin the reactors."