NRC NEWS

 U.S. NUCLEAR REGULATORY COMMISSION

 2443 Warrenville Road

 Lisle IL 60532

 Web Site: http://www.nrc.gov E-mail: opa3@nrc.gov

No. III-07-015 April 10, 2007

CONTACT: Viktoria Mitlyng (630) 829-9662 

NRC Issues a “Yellow” Inspection Finding to Kewaunee Nuclear Plant

for Failing to Promptly Evaluate Diesel Fuel Oil Leak

The Nuclear Regulatory Commission staff has determined that the failure of the Kewaunee

Nuclear Power Plant to promptly take corrective action for a diesel generator fuel leak in June 2006

was of “substantial importance to safety.” The plant, operated by Dominion Energy Kewaunee, Inc., is

located near Kewaunee, Wis.

The NRC determined the incident to be a “yellow” finding, indicating it was of substantial

importance to safety.

On June 28, 2006, plant personnel identified a leak on one of two emergency diesel generators

at the plant but did not follow procedures to evaluate the condition under the plant’s correction action

program. On Aug. 17, while performing a routine test of this diesel generator, plant workers saw a

substantial increase in the fuel oil leaking from the connection between the fuel oil line tubing and a

fitting. The testing was stopped and the diesel generator was declared inoperable. The leaking

equipment was replaced, and the diesel generator was returned to service on Aug. 18.

The utility tested the defective equipment and concluded that the leaking fuel oil system

components would have failed after four hours of diesel operation if the generator was required to

supply power to plant safety systems. The test results led the utility to conclude that the emergency

diesel generator was inoperable for 51 days.

NRC inspectors conducted an inspection to review the circumstances of the leak and reviewed

the results of tests performed by the utility.

The NRC uses color-coded inspection findings and performance indicators to assess nuclear

plant performance. The colors start with “green” and then increase to “white,” “yellow” or “red,” as

the safety significance of the issue increases. 

NRC inspectors identified one “yellow” finding of substantial importance to safety associated

with the plant personnel’s failure to follow procedures which would have required plant personnel to

evaluate how the leak would affect the diesel generator’s operability. This operability evaluation would

have shown that, under certain accident conditions, the diesel would not be able to perform its safety

function. It would have revealed the need to promptly fix the problem. 
Emergency diesel generators supply electrical power to plant safety systems if the normal

connection to off-site power sources is lost. 

“This incident shows the importance of following procedures at nuclear power plants,” said 

James Caldwell, regional administrator for NRC’s Region III office in Lisle, Ill. “Even though routine

plant operations were not affected by this issue, the utility’s failure to follow procedures could have

resulted in the failure of one of the plant’s safety systems to fulfill its function in case of an accident.

This resulted in an a reduction in plant safety margins.”

The utility’s corrective actions included replacing the leaking components and emphasizing to

plant personnel the need to follow procedures on entering issues into the corrective action program.

“Yellow” findings normally result in additional NRC inspections and meetings with the utility.

The NRC issued a Notice of Violation to Dominion Energy Kewaunee for plant personnel’s failure to

follow procedures and enter the issue into the corrective action program. The company is required to

respond to the Notice of Violation within 30 days, describing its corrective actions and steps it is

taking to prevent a recurrence of the violation.

The letter notifying Dominion of the yellow finding is available from the NRC’s Region III

Office of Public Affairs or and will be available in the NRC’s online document library at:

http://www.nrc.gov/reading-rm/adams/web-based.html (use accession number ML070940146).

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