PG&E Declares Alert at Diablo Canyon Power Plant

No risk to employee or public health

July 28, 2017

AVILA BEACH, Calif. – Pacific Gas and Electric Company’s (PG&E) Diablo Canyon Power Plant declared an Alert at 12:06 p.m. on July 28, 2017, due to a recording of slightly decreased oxygen levels in Unit 2 containment. There is no risk to employee or public health and safety. Both Units 1 and 2 are in a safe condition and remain operating at full power.

The declaration of the Alert is based on criteria set forth in the plant’s established operating and emergency procedures. It was declared because personnel who may need to access this area of the plant would potentially need to use additional breathing apparatus to enter containment during an emergency to operate equipment.  Once operators restore Unit 2 containment oxygen levels to above 19 percent -- from the current level of 18.5 percent -- and county key stakeholders agree, the Alert declaration will be lifted.

The decreased oxygen levels could be due to a variety of issues.  PG&E’s professional staff is working on understanding the situation and restoring it.

The Alert classification for this event has been removed from the emergency action levels at other stations and is in the process of being removed from emergency action procedures at DCPP pending NRC approval since the condition does not pose a risk to the health and safety of the general public.

An Alert is the second lowest of four federal classifications established by the Nuclear Regulatory Commission (NRC) for emergencies at U.S. commercial nuclear power plants. An Alert is characterized by events that are in progress or have occurred which involve an actual or potential impact on the level of safety of the plant.

Diablo Canyon personnel are well-trained to respond to this type of situation and drill regularly with local, state and federal partners to ensure a coordinated response. In accordance with pre-existing emergency plans, appropriate federal, state and local emergency organizations, including the NRC, have been notified.

PG&E will communicate the latest information on the situation with the news media via briefings at the Joint Information Center (JIC) in San Luis Obispo (see separate release for location and directions).

The public can obtain information by calling the company’s toll-free service line at 1-800-PGE-5000, or by accessing the following online resources: PG&E’s Diablo Canyon page, at; its Twitter feed, at; and the company’s Facebook page, at

About Diablo Canyon Power Plant

Diablo Canyon Power Plant is a nuclear power facility owned and operated by PG&E. Its two units together produce approximately 2,300 net megawatts of carbon-free power.