On March 11, 2012, at approximately 12:20 p.m. CDT, Byron Station Unit 1 was shut down due to the identification of a leaking valve inside containment. The purpose of this valve is to isolate the pressure equalization line for the reactor coolant system loop stop valves. The valve is only used when the steam generator undergoes maintenance during a refueling outage. The licensee identified the leaking valve when Unit 1 power was reduced to perform a planned replacement of the electrical insulators at the site. This valve is not associated with the ongoing electrical insulator replacement activities.
The plant is currently in a stable shutdown condition. The licensee plans to replace the valve before returning the reactor to power operation. NRC Resident Inspectors observed the power reduction and reactor cooldown, and continue to monitor the repair activities and assess plant conditions.
The State of Illinois has been informed of the plant shutdown. RIII received initial notification of this occurrence through the resident inspectors. The information presented herein has been discussed with the licensee, and is current as of March 14, 2012, at 12:30 p.m. (CDT).
Adams ML Number: ML12074A204
On March 11th, the Chicago Tribune reported that Exelon Corp. shut its 1,164-megawatt Unit 1 at the Byron nuclear power plant in Illinois over the weekend for “planned upgrades” of the facility’s switchyard. “We are taking a proactive step to replace insulators in the switchyard to ensure our equipment meets the highest standards,” Byron Station Site Vice-President Tim Tulon said in a statement.