NRC NEWS

U.S. NUCLEAR REGULATORY COMMISSION

Office of Public Affairs Region III

2443 Warrenville Road

Lisle IL 60532

Site: http://www.nrc.gov

Blog: http://public-blog.nrc-gateway.gov

No. III-11-007

Contact: Viktoria Mitlyng (630) 829-9662

 Prema Chandrathil (630) 829-9663

April 6, 2011

E-Mail: OPA3.RegionIII@nrc.gov 

NRC BEGINS SPECIAL INSPECTION AT BRAIDWOOD AND BYRON NUCLEAR PLANTS 

The U.S. Nuclear Regulatory Commission has started a Special Inspection to review

the handling of two equipment issues at Byron and Braidwood nuclear power stations operated 

by Exelon Generation Company.

The first issue involves the operability of backup systems that would be used to remove 

heat from the reactor in case of a reactor trip or an accident at Braidwood and Byron stations.

The second issue is associated with the loss of control room equipment alarms during 

maintenance activities in 2010 and 2011. 

Neither of the issues posed an immediate threat to public health and safety. Both 

equipment issues have been resolved.

Braidwood is located 20 miles southwest of Joliet, Ill.; Byron is located 17 miles 

southwest of Rockford, Ill.

The first issue came to light in February, when during routine NRC inspections at Byron,

NRC inspectors identified a concern with Auxiliary Feedwater (AFW) pumps. As a result, the 

NRC required Exelon to provide an assessment of this equipment’s ability to cool the reactor in 

case the normal system for heat removal became unavailable at both Byron and Braidwood 

stations which are similar in design (Exelon’s Event Notification to the NRC for Braidwood 

#46707 at http://www.nrc.gov/reading-rm/doc-collections/eventstatus/event/2011/20110330en.html#en46707 and #46708 for Byron at 

http://www.nrc.gov/reading-rm/doc-collections/eventstatus/event/2011/20110330en.html#en46708). The company’s initial evaluation was that the 

pumps would be available to perform their safety function. However, after confirmatory 

calculations were completed, the company concluded that the pumps would not be operable.

AFW pumps are not used in regular plant operation; they are designed to be used as a 

backup system in case regular reactor cooling equipment is no longer available.
The second issue is associated with the unavailability of control room equipment alarms 

and the declaration of an Unusual Event (NRC Preliminary Notification III-11-005 at 

http://pbadupws.nrc.gov/docs/ML1108/ML110830918.pdf), the lowest level of emergency in the 

NRC’s emergency classification system, at Braidwood on March 24 of this year. The review of 

past maintenance activities revealed that plant operators failed to recognize the same conditions 

while performing similar maintenance activities on Aug. 10, 2010.

The special inspection team will review the circumstances surrounding the AFW system 

issues identified at Braidwood and Byron, including the original design of the system and the

methods utilized by Exelon to arrive at the operability evaluations presented to the NRC. The 

special inspection team will also review the circumstances surrounding the unavailability of 

control room equipment alarms at Braidwood, including causes of these events, and an 

assessment of whether Byron has experienced similar events. The team will also evaluate 

Exelon’s actions to address both issues.

The NRC special inspection report will be available within 45 days of the inspection’s 

completion through the NRC RIII Office of Public Affairs and at the NRC web site: 

http://www.nrc.gov/reading-rm/adams/web-based.html. 

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