Lying on the remote north west coast of England is one of the most secret places in the country - Sellafield, the most controversial nuclear facility in Britain. Now, Sellafield are letting nuclear physicist Professor Jim Al-Khalili and the television cameras in to discover the real story. Inside, Jim encounters some of the most dangerous substances on earth, reveals the nature of radiation and even attempts to split the atom. He sees inside a nuclear reactor, glimpses one of the rarest elements...