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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 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 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).

Susquehanna Unit 2 discovered a condition that could have prevented the primary containment isolation valves for the reactor water cleanup (RWCU) system from automatically isolating on a high differential flow instrumentation signal. The RWCU system high differential flow signal was found to be indicating downscale due to an instrument failure. Both divisions of the RWCU high differential flow isolation logic utilize the same differential flow instrument loop. Thus, this single instrument failure would have prevented automatic isolation of the RWCU inboard and outboard primary containment isolation valves on a high differential flow signal. The other RWCU primary containment isolation instrumentation functions remained operable and the associated RWCU system primary containment isolation valves were capable of being remotely closed by the control room operators. At the time of discovery, Unit 2 was in Mode 2 due to an unplanned shutdown and all control rods had already been fully inserted as part of a soft shutdown sequence. The licensee has notified the NRC Resident Inspector.

• * * RETRACTION FROM DUTTRY TO KLCO ON 1/11/13 AT 2155 EST * * *

Following the ENS report (EN 48525), Susquehanna determined that although the RWCU high differential flow isolation instrumentation would have prevented automatic isolation of the RWCU inboard and outboard primary containment isolation valves on a high differential flow signal, the RWCU high flow isolation instrumentation would detect a high flow condition and generate an isolation signal that would close the isolation valves. The RWCU high differential flow instrumentation is downstream of the RWCU pumps and it calculates the difference (delta) in flow between the inlet and the outlet of the RWCU heat exchangers. The SSES (Susquehanna Steam Electric Station) Technical Specification (TS) Bases Section 3.3.6.1 states that the RWCU Differential Flow signal is to detect a break in the RWCU system (pipe severance and separation). Engineering analysis determined that the RWCU pumps would run-out if a break occurs downstream of the pumps and the RWCU system flow rate would be approximately 1000 gpm, with one RWCU pump in operation. The flow rate would be higher for two RWCU pumps in operation. Therefore, RWCU isolation would occur from the RWCU Flow - High isolation signal due to a flow rate that is greater than 472 gpm (TS Table 3.3.6.1-1). This high flow isolation does not rely on the RWCU high differential flow instrumentation. The above analysis is consistent with the FSAR discussion in section 7.3.1.1a.2.4.1.9.3. Based on the above, Susquehanna has determined that the RWCU isolation function would still be completed if a pipe break occurred downstream of the RWCU heat exchangers and the RWCU high differential flow instrumentation is inoperable. Since there was no loss of safety function of structures or systems that are needed to control the release of radioactive material, this ENS report is retracted. The licensee will notify the NRC Resident Inspector.

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).

On 06/04/2011, personnel observed the temperature control valve for the 'B' control structure chiller not operating properly. To investigate control valve operation, the controller was taken to the manual mode (from automatic) at 1614 (EDT). The control valve stem was lubricated, and the valve was operated with the controller in the manual mode. The 'B' control structure chiller was inoperable in this condition until control valve responsiveness was validated (total of 35 minutes, until 1649 (EDT)). The 'B' chiller continued to operate during this period. The 'A' control structure chiller was out of service during this timeframe to perform maintenance activities. Hence, neither chiller was operable. The control structure chillers provide control building habitability during unit operation. The control structure chillers also provide cooling water for emergency switchgear room cooling on unit one only. This condition is being reported as an event or condition that could have prevented fulfillment of a safety function per 10CFR 50.72(b)(3)(v)(D). The licensee has notified the NRC Resident Inspector.

• * * RETRACTION ON 7/22/2011 AT 1519 FROM LONNIE CRAWFORD TO MARK ABRAMOVITZ * * *

On June 4, 2011, Susquehanna reported the simultaneous inoperability of both control structure (CS) chillers as an event or condition that could have prevented fulfillment of a safety function in accordance with 10CFR 50.72(b)(3)(v)(D). After further investigation, Susquehanna has concluded that the 'A' and 'B' CS chillers were not inoperable at the same time. On June 3, 2011 at 1608, fluctuating amperage was observed on the 'A' CS chiller and the chiller was declared inoperable. As a result, the 'B' CS chiller was placed in service with the 'A' CS chiller placed in standby. Subsequent troubleshooting of the 'A' CS chiller included replacing the chiller temperature controller with a spare while the original controller was evaluated in the shop. The original controller was re-installed on June 4, 2011 at approximately 1030 but did not resolve the issue. The 'A' CS chiller was later shutdown and removed from standby on June 4, 2011 at 1727. Originally, Susquehanna believed that the fluctuating amperage on the 'A' chiller was an operability issue. Subsequent engineering evaluation has determined that the observed oscillations were not rapid enough and did not have sufficient amplitude to cause damage to the chiller motor and were within design limits. The conclusion is that the 'A' control structure chiller was operable and would continue to operate for its 30 day mission time with the observed current oscillations. Although the 'A' chiller was inoperable as a result of troubleshooting at various times on June 3 and 4, the 'A' chiller was available and operable during the short period of time on June 4 when the 'B' chiller was inoperable. . Based on the above information, this ENS report is retracted. The licensee notified the NRC Resident Inspector. Notified the R1DO (Dentel).

At 1801 on 5/16/2009, the HPCI turbine steam supply valve (HV255F001) failed to close during shutdown of the system following performance of its quarterly flow surveillance. The auxiliary oil pump was de-energized to prevent an inadvertent start of HPCI and the HPCI system was declared inoperable. LCO 3.5.1 for the HPCI system being inoperable was entered at 1720 on 5/16/2009 at the start of the HPCI surveillance. An investigation is in progress to determine the nature of the problem. This is being reported as an event or condition that could have prevented fulfillment of a safety function required to mitigate the consequences of an accident in accordance with 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.

• * * RETRACTION ON 7/16/09 AT 1543 FROM TODD CREASEY TO CHARLES TEAL * * *

On May 16, 2009, the HPCI system was declared inoperable at 1720 hours and LCO 3.5.1 was entered to support the planned quarterly HPCI flow surveillance test. During the surveillance test, at 1801 hours, the HPCI turbine steam supply valve (HV255F001) failed to close during shutdown of the system. It was also identified that neither the open nor closed indication lamp in the control room were lit. Troubleshooting was performed by cycling the valve's breaker in an attempt to restore power to the HPCI steam supply valve. No movement of the valve was observed. Because the position of the HPCI steam supply valve was unknown, Operations secured HPCI by opening the auxiliary oil pump breaker for the purpose of conducting additional troubleshooting (maintenance) of the failure of the HV255F001 valve to close. On 5/16/09 at 2004 hours EDT, Susquehanna made an 8-hour ENS notification (45703) to the NRC, due to HPCI being declared inoperable when HV255F001 failed to close during performance of the quarterly surveillance. Subsequent investigation concluded that the HPCI turbine steam supply valve (HV255F001) did close as expected, but did not indicate closed due to a loss of position indication. It was determined that the closed indicating lamp had burned out. Upon replacement of the lamp, the valve was successfully stroked open and closed and HPCI was declared operable at 0800 EDT 5/17/2009. Because a condition did not exist at the time of discovery that could have prevented the fulfillment of a safety function in accordance with 10 CFR 50.72(b)(3)(v)(D), EN #45073 is hereby being retracted. It should be noted that the subsequent action to disable HPCI by opening the auxiliary oil pump break does not preclude retraction of the ENS notification. This action did not create a new reportable condition since HPCI was already inoperable for planned surveillance testing. This action was taken as part of troubleshooting activities (maintenance) on the HV255F001 valve and to prevent an inadvertent start of HPCI. The NRC Resident has been notified. Notified R1DO (Gray)

At 09:20 am, on February 9th, the control room declared both trains of Control Structure Emergency Outside Air Supply System (CREOASS) inoperable. The control room was notified of an inoperable boundary door that was not closed and latched and therefore would not have allowed CREOASS to perform its safety function of maintaining the Control Structure at a positive pressure if required. The door was closed and locked (at 11:15) to restore the habitability boundary. The door has since been repaired (adjustment of latch mechanism). Initial investigation determined that the door had been unlocked at approximately 09:20 this morning by an elevator vendor to perform maintenance. This is being reported as an event or condition that could have prevented the fulfillment of the safety function required to mitigate the consequences of an accident. CREOASS was not called upon to function during the period that the door was not operable. The licensee notified the NRC Resident Inspector.

• * * RETRACTION FROM LICENSEE (ROBINSON) TO NRC (HUFFMAN) @ 1328 EDT ON 4/8/05 * * *

The following information was provided by the licensee (licensee text in quotes): On 2/9/2005, PPL Susquehanna LLC reported a loss of safety function for the Control Room Emergency Outside Air Supply System (CREOASS) based on one of the Control Structure Habitability boundary doors being found partially open. Positive air pressure generated by the Control Structure HVAC System prevented the door closure mechanism from maintaining the door closed. The door was closed to restore the habitability boundary. The event was reported as a condition that could have prevented the fulfillment of the safety function required to mitigate the consequences of an accident. The Safety Function of the CREOASS is to provide adequate radiation protection to permit occupancy of the Control Room under accident conditions for the duration of the accident. The CREOASS accomplishes this by: 1) filtering the outside make-up air supply and 2) maintaining a positive pressure in the control structure habitability boundary to limit unfiltered air in leakage into the boundary. A subsequent engineering evaluation concluded that with the door closure mechanism providing a resistive force, CREOASS would have been able to maintain a positive pressure within the boundary and perform its safety function as described above. In conclusion, the reported condition did not result in a loss of safety function under 10CFR50.72 (b)(3)(v)(D) and is therefore being retracted. The NRC Resident Inspector and R1DO (Noggle) have been notified.

At 0030 (ET) during setup for Unit 1 Division 1 LOCA/LOOP Surveillance testing, the controlling procedure required making the Loss of Power instrumentation for the 1A and 1C ESS buses inoperable. The specification has a 1 hour time limit for restoration, or the associated Diesel Generators must be declared inoperable. Due to delays during the setup of equipment the time requirements were not met, and the associated Diesel Generators were declared inoperable at 0130. The Susquehanna Safety Analysis requires three operable Diesel Generators to safely shutdown. Therefore, this condition is reportable for Unit 2 under 10CFR50.72(b)(3)(v). Unit 1 is in Mode 5 and therefore not impacted. The Loss of Power instruments were restored, and the Diesel Generators declared operable at 0223. The licensee notified the NRC Resident Inspector.

• * * * RETRACTION FROM R. FRY TO M. RIPLEY 1419 ET ON 05/27/04 * * * *

The following is a retraction of ENS Notification #40642 AND #40646: On April 5, 2004, PPL Susquehanna, LLC reported three events to the NRC associated with Unit 1 Division 1 LOCA/LOOP surveillance testing. In each case, the safety function of two (out of 4) emergency diesel generators was brought into question during the testing. In two of these events, the E (substituting for A) and C diesel generators were administratively declared inoperable per Technical Specifications. This was necessary because Loss of Power instrumentation for the 1A and 1C buses, rendered inoperable in support of the test procedure, was not restored within 1 hour. In the third event, the E (for A) and C emergency diesel generators were, again, declared inoperable when two ESW pump start timers failed to meet acceptance criteria thus bringing the proper start sequencing of emergency loads into question. Because the Susquehanna Safety Analysis requires three diesel generators to safely shutdown an operating unit, the potential compromise of the diesel generator safety function was a concern for Unit 2 in each instance. (NOTE: Unit 1 was in Refueling Mode 5 and was, therefore, not impacted by these events.) Accordingly, Control Room personnel conservatively initiated ENS reporting under 10CFR50.72(b)(3)(v) in response to the apparent loss of safety function for Unit 2. Subsequent engineering analysis has concluded that, although the declaration of diesel generator inoperability was correct and in accordance with Technical Specifications, fulfillment of these administrative actions did not result in an actual loss of safety function during any of the above described events. Details of the analysis show that the diesel generators were available to supply emergency power to the ESS buses and/or that sufficient redundant equipment was available to fulfill the safety function needs of Unit 2. These analysis conclusions provide the basis for retraction of the ENS reports made on April 5, 2004." The licensee notified the NRC Resident Inspector. Notified R1DO (R. Conte)

At 09:30 EDT, Unit 1 was performing the HPCI Quarterly Flow verification surveillance. Shortly after the initiation of the system an abnormally loud bang was heard. System flow of approximately 5200 gpm and discharge pressure of approximately 1300 psi was achieved at approximately 09:33. Approximately 4 seconds after reaching rated system flow HPCI discharge pressure increased to approximately 1675 psi and system flow dropped to approximately 2700 gpm. HPCI had been declared inoperable at 08:35 EDT to perform the surveillance and will remain inoperable until the cause of the loss of system flow is corrected. Because HPCI is a single train ECCS (Emergency Core Cooling System) safety system, this event results in the loss of an entire safety function which requires an 8 hour ENS notification in accordance with 10CFR50.72(b)(3)(v) and the guidance provided under NUREG-1022, rev. 2. There are no other ECCS systems presently out of service. Reactor Core Isolation Cooling (RCIC) is fully operable and HPCI entered Tech Spec 3.5.1 (14 day Limiting Condition of Operation). All other ECCS systems are fully operable. The NRC Resident Inspector was notified of this event by the licensee.

• * * RETRACTION FROM WALSH TO CROUCH ON 10/02/03 @ 1548 EDT* * *

On 09/05/2003, PPL Susquehanna LLC made an ENS notification per 10CFR50.72(b)(3)(v) in response to an apparent loss of the HPCI (High Pressure Coolant Injection) safety function. In the event, results of HPCI Quarterly Flow Surveillance testing did not meet acceptance criteria established for the system. Investigation into the cause of the failed HPCI surveillance revealed a 360-degree weld crack on the HPCI Test Line to Condensate Storage Tank (CST) Valve, HV155F008. HV155F008 is not in the reactor vessel injection flowpath. The impact of this crack, which was located between the valve seat cage assembly and the valve body, was that the HPCI Test Line to CST valve was not capable of throttling over the full range of HPCI system flows. Valve performance became erratic at higher flows because the valve seat cage was lifted out of the valve body into the flow path, increasing system resistance, and preventing attainment of design flow in the HPCI test loop. While the ability to effectively test the HPCI system using the test return path to the CST was compromised, the HPCI injection flowpath to the reactor vessel was not adversely affected by the damaged valve. Accordingly, the HPCI system maintained full capability for providing sufficient coolant to the reactor vessel in the event of a small break loss-of-coolant accident. Because the HPCI safety function was not compromised by the identified test path obstruction, this ENS notification is being retracted. The Licensee has notified the NRC Resident Inspector. Notified R1DO (Cobey).