Jamie Edwards became the youngest person in the world to achieve nuclear fusion from scratch at his Lancashire secondary school, using high energy to smash two hydrogen atoms together to make helium, Daily Mail reported.
"It is quite an achievement. It's magnificent really," Jamie said afterwards. "I can't quite believe it - even though all my friends think I am mad."
Edwards, who attends Penwortham Priory Academy near Preston, has been fascinated with radiation for years, on one occasion even buying a Geiger counter with his Christmas money.
He started building the reactor in October at the science laboratory at Priory Academy, Lancashire, and finally finished the task on Thursday.
He said that his fusion ambition was sparked by reading about a 14-year-old US schoolboy, Taylor Wilson, who had become the youngest to produce a small fusion reactor in Nevada in 2008.
"I looked at it, thought 'That looks cool' and decided to have a go," Jamie added.