WHAT WE LEARNED ABOUT NUCLEAR SAFETY from Fukushima. “Nuclear experts say the key to controlling future incidents and thus restoring faith in nuclear energy is a ‘defense in depth’ approach to reactor design and emergency preparedness—precisely what was missing at Fukushima. Locating backup air-cooled diesel generators in basements, for example, was a sign that Fukushima wasn’t fully prepared for a tsunami.” That’s like the below-sea-level backup generators in New Orleans.