Nuclear Watch: Fukushima Muon Images show no fuel inside No.1 reactor core + update 3/19/2015

Researchers say X-ray-like photos of a crippled reactor at the Fukushima Daiichi plant have confirmed that no nuclear fuel remains in the reactor core.

The finding supports the result of a simulation suggesting most of the molten fuel penetrated the core’s base.

Nuclear fuel in 3 of the plant’s 6 reactors melted down in the March 2011 nuclear accident at the plant. But extremely high radiation levels have prevented experts from locating and determining the state of the molten fuel.

Experts from the High Energy Accelerator Research Organization and other institutions have succeeded in taking X-ray-like photos of the plant’s No.1 reactor.
Since February, they have been using a type of elementary particle called the muon to get a peek inside the reactor, instead of using X-ray technology. The particles are created when cosmic rays collide with the Earth’s atmosphere.

The experts found nuclear fuel inside a storage pool located beside the No.1 reactor. But they did not find fuel inside the core of the reactor where the meltdown took place.

The finding confirms the result from an earlier computer simulation that suggested most of the fuel in the reactor core likely melted and fell through the bottom into the containment vessel housing the core.

Experts say the finding that most of the fuel had leaked out of the reactor core underlines the difficulties faced in scrapping the reactor.