05000388/LER-2015-002

LER-2015-002, Secondary Containment Inoperability Due To Failure to Meet Technical Specification Surveillance Requirement 3.6.4.1.1

Susquehanna Steam Electric Station Unit 2
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
Initial Reporting
ENS 50885	10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material
3882015002R00 - NRC Website

the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

Susquehanna Steam Electric Station, Unit 2 05000388

CONDITIONS PRIOR TO THE EVENT

Unit 1 — Mode 1, 100 percent Rated Thermal Power Unit 2 — Mode 1, 100 percent Rated Thermal Power There were no systems, structures, or components that were inoperable at the start of the event and contributed to the event.

EVENT DESCRIPTION

On March 13, 2015, at 0919 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.496795e-4 months <br />, Secondary Containment became inoperable requiring a Technical Specification (TS) 3.6.4.1, Condition A, entry for failure to meet Surveillance Requirement 3.6.4.1.1 for Susquehanna Steam Electric Station (SSES) Unit 1 and Unit 2. The Reactor Building (RB) Zone 2 differential pressure fell below the TS limit of 0.25 inches water column (wc) vacuum when an air handling plenum door was opened for approximately one minute. TS 3.6.4.1, Condition A, was exited at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> when the differential pressure returned to 0.34 inches wc vacuum. On March 13, 2015, at 1256 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.77908e-4 months <br />, this condition was determined to be reportable as an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ENS (#50885) in accordance with 10 CFR 50.72(b)(3)(v)(C) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material. SSES has no redundant Secondary Containment system.

In accordance with 10 CFR 50.73(a)(2)(v)(C), this LER is being submitted for an event or condition that at the time of discovery, could have prevented the fulfillment of the safety function of Secondary Containment to control the release of radioactive material.

CAUSE OF THE EVENT

The direct cause of the event was due to plant personnel holding the RB plenum door open for approximately one minute during the performance of radiation surveys.

The apparent causes of the event were due to: 1) an insufficient questioning attitude by plant personnel.

Plenum doors are only intended to allow momentary passage. SSES's site generic plant access training instructs personnel not to prop open plant doors, and 2) the plenum access doors were not marked with signs that notified personnel of the potential impacts/consequences to Secondary Containment by opening the door.

ANALYSIS/SAFETY SIGNIFICANCE

The actual consequence of this event was a degradation of the Secondary Containment vacuum which led to an unplanned entry into TS 3.6.4.1, Condition A, for Unit 1 and Unit 2. An Engineering evaluation was performed which concluded that Secondary Containment could have performed its safety function of isolating as assumed in the SSES accident analysis and also of re-establishing 0.25 inches wc vacuum (i.e., drawdown time) within the assumed accident analysis time of 10 minutes. Therefore, the safety function of the Secondary Containment boundary and Standby Gas Treatment systems were unaffected and remained operable during this event. As such, there were no actual consequences to the health and safety of the public.

ANALYSIS/SAFETY SIGNIFICANCE (cont.) Additionally, this event will not be counted as a safety system functional failure (SSFF) for the NRC performance indicator based on the engineering evaluation that concluded there was no loss of Secondary Containment's ability to fulfill its safety function.

CORRECTIVE ACTIONS

Key Completed Actions —

• Signs were added to the affected Unit 1 and Unit 2 exhaust fan plenum doors warning of the Secondary Containment implications.

• Plant personnel were coached regarding the use of the RB plenum doors.

Key Planned Action —

• Install signs on all major Reactor Building fan plenum doors to alert plant personnel of the Secondary Containment impacts.

PREVIOUS SIMILAR EVENTS

• LER 50-388/2014-001: Secondary Containment Personnel Airlock Doors Both Opened Resulting in Failure to meet TS 3.6.4.1

• LER 50-387(388)/2013-003-00: Loss of Secondary Containment

• LER 50-387(388)/2013-004-00: Loss of Secondary Containment Due to Differential Pressure Not Meeting Technical Specification 3.6.4.1

• LER 20-387(388)/2013-005-00: Loss of Secondary Containment