In this episode:

Following the aftermath of the Fukushima radiation scare, the team turns its attention to nuclear power. Jem climbs into a reaction chamber to explain how a nuclear power station works and what happened in Japan. Meanwhile, Dallas investigates the clean-up operation for radioactive waste, and Liz looks at what radiation does to the human body.

http://www.bbc.co.uk/i/b015t2rr/