Inside Japan's Ghost Zone

It has been six months since Japanese emergency workers began a desperate struggle to control the nuclear power station at Fukushima. Three of the reactors were over-heating following the tsunami, and a vast cloud of radioactivity escaped and more than 100,000 people living within 12 miles of the plant were ordered out.

Today, the reactors are still not fully stabilized, but radiation levels in one area of the exclusion zone have dropped — the BBC's science correspondent, David Shukman is one of the few journalists to make the journey inside.