Davis-Besse Nuclear Power Station slipped from what's considered an "A" performance status to a "B" during the 2009 operating year.
The reason for the downgrade is a low-to-moderate level safety violation that occurred last June.
During the regular annual review between the Nuclear Regulatory Commission and FirstEnergy on Thursday night, the NRC outlined the circumstances leading to the violation.
On June 25, 2009, the plant experienced a small explosion and fire in the switchyard of the facility. According to its emergency policies, staff at the plant should have recognized the incident as meeting criteria for an alert. An alert is a low-level emergency that requires the plant to notify the NRC, state and local officials.
Staff at the plant did not immediately issue the alert, and only recognized the error after the next shift started. At that time, they notified the required agencies.
Because of its failure to properly assess and respond to the situation, the NRC issued the plant a "white" mid-level violation. The public was not in danger during the situation because no critical systems were affected by the fire or the explosion.
NRC regulators, however, said they were concerned about a flawed decision-making process illuminated by the response.
"If you can't respond correctly to the little things, how do we know that you are going to respond correctly to something big?" NRC spokeswoman Viktoria Mitlyng explained after the meeting.
Davis-Besse site vice president Barry Allen said the facility has addressed the problem by updating its emergency procedures and providing additional training to its staff.
Because of the violation, the NRC will spend an additional 40 hours of inspection time at the plant to make sure the new procedures are working.
Davis-Besse will have to maintain good operating status for four quarters before its ranking can be moved back to "A" status. If the facility has other notable violations during that time, the NRC can downgrade the ranking.
Of the 104 nuclear power plants in the United States, 79 had the equivalent of "A" rankings for 2009. Twenty-four plants, including Davis-Besse, were "B" rankings and one was considered a "C" ranking.
No plants had "D" or "F" rankings.
The plant is back in operation after FirstEnergy fixed cracked nozzles on the nuclear reactor head discovered this spring during a regular refueling outage. The company agreed to replace the whole reactor head in October 2011.
Ottawa County resident Howard Whitcomb, who attended Thursday's meeting, pressured the NRC to answer why it believes the plant can operate safely with the old reactor head until then.
"Based on our review of the head moving forward, based on the engineering analysis, it is acceptable for use through October of next year," said NRC branch chief Jamnes Cameron.
He said based on independent NRC calculations, the type of cracking and boric acid leakage seen this year and to a greater extent in 2002 is unlikely in such a short time.
"It's not an overnight phenomenon," he said.
The NRC will have another public meeting sometime soon to specifically address the cracking issue when regulators have completed an investigation.
LEVELS OF SAFETY VIOLATIONS
The Nuclear Regulatory Commission uses the following color-coded levels for safety violations. Davis-Besse received a "white" violation last year for an incident on June 25, 2009. It will have to operate in good standing for four quarters before it will return to "green" status.
GREEN: Very Low Safety Significance
WHITE: Low to Moderate Safety Significance
YELLOW: Substantial Safety Significance
RED: High Safety Significance