Diablo Canyon nuclear power plant declared an alert for seven hours Friday due to slightly decreased oxygen levels in one of its containment buildings, but it was “not anything that’s a threat to the public’s health or safety,” said Ron Alsop, manager of the county Office of Emergency Services.
Oxygen levels dropped to 18.5 percent, below the required 19 percent level, in the plant’s Unit 2 containment building, said Blair Jones, a PG&E spokesman. The incident poses no risk to employee safety, he said.
The alert was declared because personnel who may need to access this part of the plant may need to use breathing apparatus, Jones said. Oxygen levels were restored Friday evening and the alert was called off, according to Jones.
Both the plant’s units are in a safe condition and remain operating at full power.
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The Office of Emergency Services procedurally activated its Emergency Operations Center to “coordinate face-to-face with PG&E,” Alsop said.
This is the second time in Diablo Canyon’s history that an alert has been issued, he said. An alert is one step up from an “unusual event,” which is the lowest incident notification level required by federal law.
Diablo Canyon’s first alert occurred in 2010, when unhealthy levels of carbon dioxide flooded a room where lubrication oil was being stored. No one was injured in that incident, nor was an evacuation warranted. Montaña de Oro State Park, just the north of the plant, was closed then, but not evacuated. That action was not warranted Friday, Alsop said.
The decreased oxygen levels could have been caused by a “variety of issues,” and PG&E staff are working to figure out the situation, Jones said.
Other nuclear power plants no longer declare an alert after such an incident because it doesn’t pose a public health or safety risk, Jones said. Diablo Canyon is in the midst of making a similar change, pending Nuclear Regulatory Commission approval.
Check back for updates on this continuing story.