Two teenage boys jumped a security fence at a research reactor in the San Francisco Bay Area, but there was no threat to the facility that uses highly enriched uranium that could be used to make a nuclear bomb.
They left the area when approached by security, said a news report.
The reactor is a venture between General Electric Co and Hitachi Ltd.
GE said in a release that the boys did not breach the inner perimeter fence or access any operational areas and were immediately approached by security.
According to the news report, the Bay Area site is one of few in the country working with highly-enriched uranium, of the kind that can be used in nuclear bombs.