In 1986, the fourth reactor at the Chernobyl nuclear complex in the Ukraine exploded and caught fire, spreading a radioactive cloud across Europe in the world's worst nuclear disaster.

CNN: Saturday,

One of them, Rear Admiral Simon Lister, is in charge of this complex programme, and as he took me round the cramped corridors, past the nuclear reactor and down into the sweaty machine rooms, he acknowledged this was a prototype and there was always going to be some "teething" issues.

BBC: HMS Astute recovers from shaky start