Assessing Fukushima Damage Without Eyes on the Inside

Inside the complex, there are three wrecked reactor cores, twisted masses of hundreds of tons of highly radioactive uranium, plutonium, cesium and strontium. After the meltdown, which followed a tsunami and earthquake in 2011, most of the material in the plant’s reactors resolidified, in difficult shapes and in confined spaces, wrapped around and through the structural parts of the reactors and the buildings.

Or at least, that is what the engineers think. Nobody really knows, because nobody has yet examined many of the most important parts of the wreckage. Though three and a half years have passed, it is still too dangerous to climb inside for a look, and sending in a camera would risk more leaks. Engineers do not have enough data to even run a computer model that could tell them how much of the reactor cores are intact and how much of them melted, because the measurement systems inside the buildings were out of commission for days after the accident.

To clean up the reactors, special tools must be custom-made, according to Duncan W. McBranch, the chief technology officer at Los Alamos National Laboratory, and the tools “can be much better designed if you had a good idea of what’s inside.” But “nobody knows what happened inside,” he said. “Nobody wants to go in to find out.”

That is where muons come in.

[link to www.nytimes.com]