Event Notification Report for April 09, 2012

BOTH CONTROL STRUCTURE CHILLERS DECLARED INOPERABLE WHILE SWITCHING POWER SUPPLIES

"On 4/9/2012, starting at 0102 EDT, the 'A' and 'C' Emergency Diesel Generators (EDG) were sequentially and briefly declared inoperable to switch their DC control power back to their normal supplies. Switching power to the normal supply is required by Unit 2 technical specification 3.8.4 following maintenance work on the U1 power supplies. Previously, at 18:35 EDT on 4/4/2012, the 'B' Control Structure Chiller was declared inoperable due to an unrelated problem. With the 'B' Control Structure Chiller inoperable coincident with the 'A' EDG or 'C' EDG inoperable, neither Control Structure Chiller would be available to perform its design function on a loss of offsite power. This is a condition that, at the time of discovery, could have prevented fulfillment of a Safety Function and is reportable under 50.72(b)(3)(v)(D) as an 8 hour notification.

"Switching the power supplies was a planned evolution. The duration of the loss of safety function was a total of eight minutes. As a mitigating action, operators were continuously available with communication to the control room. The associated diesel generator could have been returned to an operable condition promptly if required.

"Note that Technical Specifications allows four hours to correct the condition before further actions are required, i.e. declare the features ('A' Control Structure Chiller) supported by the inoperable diesel inoperable."

The licensee notified the NRC Resident Inspector.

***RETRACTION FROM RON FRY TO S. SANDIN ON 6/7/12 AT 0205 EDT***

The licensee is retracting this report based on the following:

"On April 9, 2012, Susquehanna reported that the 'A' and 'C' Emergency Diesel Generators (EDGs) were sequentially and briefly declared inoperable to switch their DC control power back to their normal supplies while the 'B' Control Structure Chiller was inoperable. The basis for the 8 hour notification, which was reported under Reporting Requirement 50.72(b)(3)(v)(D), was the conclusion that neither Control Structure Chiller would be available to perform its design function on a loss of offsite power.

"The reporting guidance in NUREG-1022, Revision 2 identifies events or conditions that are generally not reportable in accordance with 50.72(b)(3)(v). One of the identified conditions is 'removal of a system or part of a system from service as part of a planned evolution for maintenance or surveillance testing when done in accordance with an approved procedure and the plant's TS (unless a condition is discovered that could have prevented the system from performing its function).' After further review, Susquehanna has determined that an ENS report was not required for this event since the EDGs and the associated 'A' Chiller were removed from service as part of a planned evolution in accordance with approved procedures and the plant Technical Specifications and no condition was discovered that could have prevented the EDGs and associated 'A' chiller from performing their function.

"Based on the above information, this ENS report is retracted."

The licensee informed the NRC Resident Inspector. Notified R1DO(Cahill).

VALID EMERGENCY DIESEL GENERATOR ACTUATION

"On April 9, 2012, at 0529 hours, electrical power was lost to the 4160 V emergency bus E1. Activities to support testing of emergency bus E1 were in progress when technicians connected a recorder across the terminals of an under-voltage relay on emergency bus E1 and caused the normal supply breakers for emergency bus E1 to open.

"The power loss to emergency bus E1 affected both Unit 1 and Unit 2. Emergency diesel generator #1 automatically started and re-energized the E1 emergency bus.

"Unit 1 was in Mode 5 and electrical systems were aligned to support testing of emergency bus E1. As a result, no other safety system isolations or actuations occurred. Per design, no Unit 2 safety system isolations or actuations occurred.

"The safety significance of this event is minimal. Safety systems functioned as designed when emergency bus E1 de-energized. There was no interruption of Unit 1 shutdown cooling as a result of this event. Normal power supply was restored to emergency bus E1 and emergency diesel generator #1 was shutdown at 0701 hours.

"Reporting requirements met by this notification: 10CFR50.72(b)(3)(iv)(A) with specified system in 10CFR50.72(b)(3) (iv)(B)(8). The NRC Resident Inspector has been notified."

PART 21 REPORT - HK CIRCUIT BREAKER STUDS FAILED TO MEET SPECIFICATION

"This letter is submitted in accordance with 10 C.F.R. 21.21(d)(3)(ii) with respect to a failure to comply with the specifications associated with two studs P/N 163392A00 and 192247A00 used in medium voltage HK circuit breakers that may be subject to failure due to hydrogen embrittlement due to incorrect processing during plating. These studs were manufactured at the ABB Medium Voltage Service facility in Florence, SC from steel rod, heat treated in-house, and then sent to Surtronics for zinc plating with chromate treatment, including hydrogen embrittlement relief baking immediately following plating. A total of 51 pieces of P/N 163392A00 and 104 pieces of P/N 192247A00 were plated by Surtronics."

* * * UPDATE FROM DAVID BROWN VIA FAX AT 1309 EDT on 4/27/12 * * *

The vendor has notified the affected licensees, removed all remaining studs from inventory and will be auditing Surtronics established process during the next finishing production run.

The licensees affected include EFH/Luminant, Progress Energy and TVA.

Notified R1DO (Jackson), R2DO (Musser), R3DO (Lara) and R4DO (Proulx).

* * * UPDATE FROM DAVID BROWN TO DONG PARK VIA FAX AT 1318 EST on 12/16/16 * * *

"This [update] amends the previous 10CFR Part 21 Notification of 27 April 2012 that reported failed studs on 7.5 and 15 kV HK circuit breakers. This amendment is required to encompass a wider time period during which the stud (PIN: 163392A00) was sold for use in medium voltage HK circuit breakers. The previous report addressed orders between September 2011 and March 2012, but based upon a recent notification reported by TVA, our notification should have extended further in the past. Further research indicates that a shift in plating vendors in November 2010 is the likely starting point for this issue."

Notified R1DO (Schroeder), R2DO (Michel), R3DO (Dickson), R4DO (Kellar), and Part 21 group via email.