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On 5/22/2019, the 'A' Control Structure Chiller (Div I) tripped due to a loss of (motor control center) MCC 0B136. The 'B' Control Structure Chiller was already inoperable due to Div II (Emergency Service Water) ESW being out of service for planned maintenance. With the loss of Control Structure HVAC System the ability to maintain temperatures in various spaces including relay rooms, Control Room Floor Cooling and Emergency Switchgear rooms was lost. The 'B' Control Structure Chiller was restarted at 0251 EDT and cooling was reestablished to the required areas, however the 'B' chiller is not considered operable at this time. Units 1 and 2 entered (Technical Specification) TS 3.0.3 at 0256 EDT and a controlled shutdown of both units commenced, Unit 2 at 0340 EDT and Unit 1 0350 EDT. This constitutes a TS required shutdown and requires a 4 hour (Emergency Notification System) ENS notification in accordance with 10 CFR 50.72(b)(2)(i). The failure also requires an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(v) due to the loss of a safety function. The licensee needs to restore the 'B' loop of ESW to exit the Limiting Condition of Operation (LCO). The licensee is currently performing a flow surveillance, once complete and assuming the data is acceptable, the licensee will be able to exit the LCO. The units are in a normal electrical lineup. The licensee will be notifying the state of Pennsylvania FEMA Operations Center. The licensee has notified the NRC Resident Inspector.

• * * UPDATE ON 05/22/2019 AT 1302 FROM SCOTT MYRTHEL TO THOMAS KENDZIA * * *

On 5/22/2019 at 0601 EDT Susquehanna Steam Electric Station reported a shutdown had been commenced at 0340 EDT for Unit 2 and 0350 EDT for Unit 1 due to inoperability of both control structure chillers. Power has been restored to MCC 0B136, and at 0901 EDT the 'A' control structure chiller was declared operable and LCO 3.0.3 was exited. Power reduction for both units was halted at 0901 EDT and preparations for power restoration initiated. As of 1255 EDT on 5/22/2019, Unit 1 power is 94% and Unit 2 power is 92%. Notified the R1DO (Arner).

On February 15, 2017 at 1337 (EST), Secondary Containment Zone 1 (Unit 1 Reactor Building) differential pressure lowered to 0 inches WG (Water Gauge) due to a trip of the running Unit 1 B Filtered Exhaust Fan. Required differential pressure per SR (Surveillance Requirement) 3.6.4.1.1 could not be maintained. Zone 1 differential pressure recovered to greater than 0.25 inches WG less than one minute later after start of the standby Zone 1 Filtered Exhaust Fan. Zone 2 (Unit 2 Reactor Building) and Zone 3 (Common Areas of Unit 1&2 Reactor Buildings) ventilation remained in service and stable. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG-1022, Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. Post-maintenance testing was underway when the fan tripped. While the investigation is on-going to determine the cause, the licensee does not believe the maintenance or testing caused the fan to trip The licensee has notified the NRC Resident Inspector.

• * * RETRACTION FROM RONALD FRY TO DONALD NORWOOD AT 0833 EDT ON 4/12/2017 * * *

The Unit 1 B Filtered Exhaust Fan trip that resulted in loss of secondary containment differential pressure occurred during post maintenance testing (PMT). The PMT was being performed following replacement of a flow controller associated with the Unit 1 B Filtered Exhaust Fan. In support of the PMT, Technical Specification (TS) 3.6.4.1 Condition A had been entered and was in effect at the time of the fan trip. The maintenance and the associated PMT were performed in accordance with approved work instructions/procedure. Subsequent to the initial report, Susquehanna troubleshooting determined that the fan trip was the result of an internal leak in the newly installed controller that prevented the new controller from functioning properly. The condition was therefore determined to have been the result of the completed maintenance. NUREG-1022, Section 3.2.7, includes the following guidance: '...reports are not required when systems are declared inoperable 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 would have resulted in the system being declared inoperable).' Following completion of the troubleshooting, Susquehanna determined that, per NUREG-1022, Section 3.2.7, the event was not reportable. Secondary Containment was declared inoperable as a part of a planned evolution for maintenance which was done in accordance with an approved procedure and the Susquehanna TS. The discovered condition was not a pre-existing condition that would have resulted in the system being declared inoperable prior to the planned maintenance activity. The licensee notified the NRC Resident Inspector. Notified R1DO (Jackson).

On September 27, 2016 at 1644 (EDT), damaged ductwork was identified in the secondary containment boundary associated with reactor building zone 3 (Units 1 and 2) recirculation plenum. The size of the hole in the secondary containment boundary was determined to be 22.5 square inches. Due to exceeding allowable total leakage in the current secondary containment isolation configuration, a violation of SR 3.6.4.1.5 (occurred). Action to establish a tested configuration with sufficient inleakage margin to restore compliance with SR 3.6.4.1.5 was completed September 27, 2016 at 2115 hrs. This event is being reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Rev 3, Section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee notified the NRC Resident Inspector.

• * * RETRACTION AT 1444 EST ON 11/23/2016 FROM MANU SIVARAMAN TO MARK ABRAMOVITZ * * *

Following the 8 hour 10 CFR 50.72 notification made on September 27, 2016 (EN 52266), further engineering analysis determined that the as-found tear in the Zone 3 ductwork did not impact the ability of Secondary Containment to perform its safety function and that Secondary Containment was not inoperable as a result of the condition. To support the determination, a drawdown test was conducted in a limiting configuration (i.e. least inleakage margin). No substantial change in drawdown testing results were observed over the last three tests. These tests spanned over seven years. Additionally, repairs were promptly made to the affected area. As a result, this event notification is being retracted as it is not reportable pursuant to 10 CFR 50.72(b)(3)(v)(C). The licensee notified the NRC Resident Inspector. Notified the R1DO (Dwyer).

On December 06, 2015 at 0350 (EST), Reactor Building Zone 1 Secondary Containment differential pressure lowered to less than 0.25 inch Water Column (WC) (degrading vacuum) when the intake supply plenum screens were found to be iced over. This required a TS 3.6.4.1 entry for failure to meet SR 3.6.4.1.1 on Unit 1 and Unit 2.

Snow melt heaters were manually started to melt the ice allowing restoration of Reactor Building Zone 1 Secondary Containment differential pressure to greater than 0.25 inch WC at 0434 on December 06, 2015. This event is being reported under 10 CFR 50.72 (b)(3)(c) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee has notified the NRC Resident Inspector.

On November 12, 2015 at 1132 hrs. (EST), Secondary Containment became inoperable due to failure to meet SR 3.6.4.1.1 requirements on Unit 2.

The inoperability was caused when RB (Reactor Building) Zone II differential pressure (D/P) oscillated between 0.23 and 0.43 inches WG (water gauge) (less than SR 3.6.4.1.1 requirement of greater than or equal to 0.25 inches WG). The oscillations subsided at 1501 (EST) and RB Zone II D/P continues to be maintained at approximately 0.35 inches WG. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector.

On 8/27/2015 at 1347 (EDT), a cart and personnel were being traversed through an airlock in the Unit 2 reactor building and both airlock doors were inadvertently opened at the same time for a brief period of time (approximately one minute). Secondary Containment differential pressure was maintained throughout the time period that the doors were opened. The doors serve as a Secondary Containment boundary and at least one in series is required to be closed at all times for Secondary Containment Operability. This event is being reported under 10 CFR 50.72(b)(3)(v) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The licensee notified the NRC Resident Inspector.

• * * RETRACTED ON 10/22/15 AT 1645 EDT FROM ALEX MCLELLAN TO DONG PARK * * *

NUREG-1022, Revision 3, Section 3.2.7, 'Event or Condition that Could Have Prevented Fulfillment of a Safety Function,' states, in part, that 'events covered in paragraph (b)(3)(v) of this section may include one or more procedural errors, equipment failures, and/or discovery of design, analysis, fabrication, construction, and/or procedural inadequacies.' The level of judgment for reporting an event or condition under this criterion is a reasonable expectation of preventing fulfillment of a safety function. A SSC (System, Structure, and/or Component) that has been declared inoperable is one in which the SSC capability has been degraded to the point where it cannot perform with reasonable expectation or reliability. For SSCs within the scope of this criterion, a report is required when: - There is a determination that the SSC is inoperable in a required mode or other specified condition in the TS (Technical Specification) applicability, -The inoperability is due to one of more personnel errors, including procedure violations; equipment failures; inadequate maintenance; or design, analysis, fabrication, equipment qualification, construction, or procedural deficiencies, and -No redundant equipment in the same system was operable. Subsequent to the reporting of this condition, Susquehanna Nuclear, LLC performed an investigation of the event. Below are the results. When the airlock doors were opened at the same time, they were being operated as designed. Each individual had a 'green' light, which allowed them to open each door. Based on the investigation, the doors were open at the same time for approximately one second. In summary, the inoperability of Secondary Containment was not due to personnel error or a procedure violation. At the time of the event, both airlock doors were operable. No equipment failures, inadequate maintenance, or design, analysis, fabrication, equipment qualification, construction, or procedural deficiencies were identified. In summary, based on the above, the identified condition is not reportable in accordance with 10 CFR 50.72(b)(3)(v), for an event or condition, that at the time of discovery, could have prevented the fulfillment of a safety function. As such, this 8-hour event notification is being retracted. The licensee has notified the NRC Resident Inspector. Notified R1DO (Gray).

On March 13, 2015 at 0919 (EDT), Secondary Containment became inoperable, requiring a Technical Specification 3.6.4.1 entry for failure to meet SR (Surveillance Requirement) 3.6.4.1.1 on Unit 1 and Unit 2.

The inoperability was caused by Zone 2 differential pressure lowering to less than 0.25 inches WC (water column) when an air handling plenum door was opened for an extended period. The plenum door was closed and differential pressure restored to greater than 0.25 inches WC at 0930 on March 13, 2015. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev. 3 Section 3.2.7, as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system. The licensee notified the NRC Resident Inspector.

On November 13, 2013 at 0226 (EST), Secondary Containment Zone II (Unit 2 Reactor Building) differential pressure was lost during restoration of a ventilation drawdown test. During restoration Unit 2 'A' Train Reactor Building Ventilation fans tripped. The 'B' Train fans were placed in service and secondary containment was restored. Zone I (Unit 1 Reactor Building) and III (Common Refuel Floor Area) ventilation remained in service and stable. Zone II differential pressure recovered within a few minutes and was verified to be stable. LCO 3.6.4.1 was exited for both units at 0257 (EST). Tech Spec Secondary Containment Operability requires a negative pressure of at least 0.25 inches water gauge. There have been no further perturbations in differential pressure and secondary containment remains operable. This event is being reported under 10 CFR 50.72(b)(3)(v)(c) and per the guidance of NUREG 1022 Rev 3 section 3.2.7 as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment System. The cause of the Unit 2 "A" Train Reactor Building ventilation fans tripping is still under investigation. The licensee has notified the NRC Resident Inspector.

• * * RETRACTION ON 1/10/14 AT 1657 EST FROM DOUG LAMARCA TO NESTOR MAKRIS * * *

NUREG-1022, Revision 3 states, ' reports are not required when systems are declared inoperable 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 would have resulted in the system being declared inoperable).' The event reported in this event notification occurred during a pre-planned evolution for surveillance testing that was done in accordance with an approved procedure and the Susquehanna Technical Specifications. The loss of differential pressure occurred during restoration from the surveillance test and occurred prior to completing the planned evolution and declaring the system OPERABLE. Specifically, the trip of the fans occurred when restoring the Reactor Building normal ventilation after a Zone 1, 2, and 3 isolation (returning back to normal ventilation from the Standby Gas Treatment System). The secondary containment boundary and standby gas treatment system were unaffected. This event occurred as a result of the testing process and would not have occurred during normal operation of the system. There was no discovered condition that would have resulted in the safety function of the system being declared inoperable under normal, non-testing conditions. Based on the above additional information, PPL is retracting this report. Susquehanna was in a planned evolution and did not discover a condition that could have prevented performing a safety function. The licensee has notified the NRC Resident Inspector. Notified the R1DO (Schmidt).

At 1540 (EDT) on 4/17/12, with Unit 1 in mode 5 and Unit 2 in mode 1, the Work Control Center was notified that the U1 #2 Main Stop Valve (MSV) was disassembled. The U1 #2 MSV was required to be intact to maintain Unit 1 Secondary Containment. Ongoing work on the D Main Steam Line Outboard Valve created a pathway that violated Unit 1 secondary containment integrity. Unit 1 Secondary Containment is required to be operable for Unit 2 while Unit 1 Zone 1 is aligned to the Recirculation Plenum. Unit 1 Zone 1 was isolated from the recirculation plenum and Unit 2 Secondary Containment was restored at 1643 (EDT) on 4/17/12. Unit 2 Secondary Containment differential pressures were maintained throughout the event. This is considered a loss of an entire safety function and requires an 8 hour report per 10CFR50.72(b)(3)(v)(C). The licensee is still investigating the cause but it appears to be associated with recent administrative changes to the Reactor Vessel draining definition and work process procedures. The licensee has 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 17, 2012, work on the Unit 1 'D' Main Steam Line Outboard Valve with the Unit 1 #2 Main Stop Valve disassembled created a pathway that violated Unit 1 secondary containment integrity. Since Unit 1 Secondary Containment is required to be operable for Unit 2 while Unit 1 Zone 1 would be aligned to the Recirculation Plenum in the event of a secondary containment isolation signal, the condition impacted Unit 2 Secondary Containment. Susquehanna considered the impact a loss of safety function and reported the impact in accordance with 10CFR50.72(b)(3)(v)(C). Following the ENS report, Susquehanna analyzed the impact of the opening. Calculations were performed that show secondary containment would have maintained the dose consequences to the public and control room operators within regulatory limits (10 CFR 50.67) assuming a Unit 2 design basis accident (Unit 1 was in a refueling outage at the time of the condition). Based on the above information, Susquehanna has determined that there was no loss of safety function and this ENS report is retracted. The licensee informed the NRC Resident Inspector. Notified R1DO(Cahill).