UPDATE: Carbon dioxide leak at Diablo Canyon first in plant's history

UPDATE: The alert was lifted officially at 5:15 p.m., according to a PG&E spokesman.

For the first time in its history, Diablo Canyon nuclear power plant Wednesday declared an alert when unhealthy levels of carbon dioxide flooded into a lubrication oil storage room at the plant.

Workers had finished performing maintenance on a valve on the room’s fire suppression system and were in the process of testing it when the accident occurred, said Jim Becker, plant manager.

The test called for a puff of carbon dioxide to be released. However enough of the gas was released to make it unsafe for people to be in the room without a breathing apparatus.

The alert was declared at 10:56 a.m. An alert is one step up from an unusual event. Alerts are called when an incident poses an “immediate danger to life and health,” Becker said.

“This is the first time this has happened at the plant,” Becker said. “I can state that categorically.”

No one was injured in the accident, no radiation was released and the plant continues to operate at full power. Plant operators, with the help of Cal Fire, are working to ventilate the room to the point where it is safe for people to enter.

As a precaution, emergency services officials decided to close but not evacuate Montana de Oro State Park to the north of the plant. The closure remains in effect, said Ron Alsop, county emergency services coordinator.

Rooms that store flammable liquids are equipped with fire suppression systems that use gases such as carbon dioxide that displace oxygen in the room when released and put the fire out.

Operators investigating the accident to determine what went wrong with the testing of the system to cause too much carbon dioxide to be released, Becker said. Reach David Sneed at 781-7930.