05000387/LER-2015-005, Regarding Loss of Secondary Containment Differential Pressure During Ventilation Damper Testing

Regarding Loss of Secondary Containment Differential Pressure During Ventilation Damper Testing

ML15176A819
Person / Time
Site:	Susquehanna
Issue date:	06/25/2015
From:	Franke J Susquehanna
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
PLA-7354 LER 15-005-00
Download: ML15176A819 (3)

LER-2015-005, Regarding Loss of Secondary Containment Differential Pressure During Ventilation Damper Testing

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
3872015005R00 - NRC Website

text

• JUN 2 5 2015 Jon A. Franke

• Site Vice President U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.2904 Fax 570.542.1504 Jon. Franke@talenenergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387(388)/2015-005-00 UNIT 1 LICENSE NO. NPF-14 UNIT 2 LICENSE NO. NPF-22 PLA-7354 TALE N~

ENERGY Docket No 50-387 and 50-388 Attached is Licensee Event Report (LER) 50-387(388)/2015-005-00. On May 4, 2015, Secondary Containment differential pressure was lost during maintenance activities on Secondary Containment exhaust fan discharge dampers. This event was determined to be reportable under 10 CFR 50.73(a)(2)(v) as a condition that could have prevented the fulfillment of the safety function of the Secondary Containment system.

There were no actual consequences to the health and safety of the public as a result of this event.

No regulatory commitments are associated with this LER.

Attachment: LER 50-387(388)/2015-005-00 Copy:

NRC Region I Mr. J. E. Greives, NRC Sr. Resident Inspector Mr. J. A. Whited, NRC Project Manager Mr. B. R. Fuller, PA DEP/BRP

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

6. LER NUMBER I

SEQUENTIAL NUMBER YEAR 2015

- 005 I

REVISION NUMBER

- 00

3. PAGE 2 of 2 There were no systems, structures, or components that were inoperable at the start of the event and contributed to the event.

EVENT DESCRIPTION

During Susquehanna's Unit 2 1 ylh Refueling and Inspection Outage in April 2015, a clearance order was applied to Unit 2 Zone Ill Reactor Building ventilation [EllS System Code VA] exhaust fan inlet dampers in support of maintenance activities on the system.

Upon completion of the maintenance activities, the clearance order was removed on May 4, 2015. During removal of the clearance order, the ventilation dampers were repositioned open in anticipation of restoring the Unit 2 Zone Ill Reactor Building ventilation system to service. Following the removal of the clearance order and damper repositioning, a ventilation damper located at the outlet of an exhaust fan was stroked open as part of a maintenance activity. By stroking this outlet damper open while the inlet dampers were open, a vent path from Zone Ill was inadvertently established and, as a result, Zone Ill differential pressure on both units degraded to below the Technical Specification (TS) Surveillance Requirement (SR) minimum value of 0.25 inches of water gauge.

Limiting Condition for Operation (LCO) 3.6.4.1 was entered at 1439 on both units. In accordance with the required actions for LCO 3.6.4.1, fuel handling evolutions were placed on hold. The outlet damper was immediately closed and Zone Ill differential pressure was restored to above the TS SR minimum value after approximately two minutes. LCO 3.6.4.1 was exited at 1452.

At 2144, emergency notification (EN) 51040 was communicated to the NRC to report this event as an event or condition that could have prevented fulfillment of a safety function. Using the guidance in NUREG-1022, this event was determined to be reportable under 10 CFR 50.73(a)(2)(v) as a condition that could have prevented the fulfillment of the safety function of the Secondary Containment system.

CAUSE OF THE EVENT

The apparent cause of the event was determined to be that Operations shift supervision did not adequately assess the impact to the plant prior to releasing stroking of the Zone Ill exhaust fan outlet damper.

ANALYSIS/SAFETY SIGNIFICANCE

There were no actual consequences to the health and safety of the public as a result of this event. The fan exhaust dampers are outside the isolation (inlet) dampers. Therefore there was no impact on the Standby Gas Treatment System's ability to drawdown secondary containment. Based on an engineering evaluation, Secondary Containment could have performed its safety function of isolating as assumed in the accident analysis and also of re-establishing 0.25 inch of vacuum water gauge within the assumed accident analysis time. Therefore, this event did not cause a loss of safety function.

CORRECTIVE ACTIONS

Following restoration from the event, action was taken to close the Unit 2 Zone Ill Reactor Building ventilation exhaust fan inlet dampers until the Unit 2 Zone Ill system was returned to service. Key planned corrective actions include revising operating and administrative procedures to require applicable dampers to be closed and status control tags applied when either unit's Zone Ill Reactor Building ventilation system is shutdown.

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CR-856695: Loss of Zone Ill differential pressure durinQ exhaust fan outlet damper strokinQ