(CNN) -- A Swedish man is being investigated by police after apparently trying to put together a nuclear reactor in his apartment, Sweden's nuclear watchdog said Thursday.
The man, named in local media reports as 31-year-old Richard Handl, contacted the Swedish Radiation Safety Authority in July to ask whether he was allowed to build a nuclear reactor, the organization's research director Leif Moberj told CNN.
That contact led the authorities to swoop down on his home in Angelholm, a coastal town of about 40,000 people known for its long sandy beaches.
"We realized he probably had radioactive material at his home which you are not allowed to have without a permit, which was why the authorities decided to inspect his home," Moberj said.
Radioactive material was found during an "extensive" inspection last month, although testing suggested radiation levels were too low for his neighbors to be worried, Moberj said.
The material included "small amounts" of Americium-241, a component of smoke detectors which cannot legally be removed from the detector casing, he said. The agency has not yet confirmed what other radioactive materials were found at the property.
Handl was quoted by the Helsingborgs Dagblad newspaper as saying he had his own Geiger counter and had not noticed any problems with radiation.
He never got the reactor going as he had just bought what was needed, Handl was quoted as saying, and now all his equipment has been taken away. Handl told the newspaper he intended to keep to the "theoretical level" in future.
Moberj said the situation was "extremely unusual" in Sweden. "I haven't heard of any similar things ever," he said.
According to the U.S. Environmental Protection Agency, the man-made radioactive metal americium "poses a significant risk" to health if ingested or inhaled. It recommends never dismantling or burning a smoke detector at home.