Inside Sellafield's death zone with the nuclear clean-up robots

The Thorp nuclear reprocessing plant at Sellafield, Cumbria, has recycled its final batch of reactor fuel. But it leaves behind a hugely toxic legacy for future generations to deal with. So how will it be made safe? Thorp still looks almost new; a giant structure of cavernous halls, deep blue-tinged cooling ponds and giant lifting cranes, imposing in fresh yellow paint. But now the complex process of decontaminating and dismantling begins.