The US Government Oak Ridge facility for handling, processing and storing weapons-grade uranium was temporarily shut recently after anti-nuclear activists climbed over security fences. The activists included an 82-year-old nun identified as Megan Rice.

The facility was manned by WSI Oak Ridge, owned by the international security firm G4S. The activists painted slogans and threw what they said was human blood on the wall of the facility, one of numerous buildings in the facility known by the code name Y-12 that it was given during World War II.

While moving between the perimeter fences, the activists triggered sensors that alerted security personnel. But officials conceded the intruders were still able to reach the building’s walls before security personnel got to them. Ellen Barfield, a spokeswoman for the activists who called themselves “Transform Now Plowshares,” said three were arrested and charged with vandalism and criminal trespass. The three arrested were Megan Rice, Michael Walli, 63, and Greg Boertje-Obed, 57.

Officials said that the storage building itself, which was built after the September 11, 2001, Al-Qaeda attacks on New York and Washington, was designed with modern security features and that its contents were not compromised.