05000387/LER-2016-012

LER-2016-002, Secondary Containment declared inoperable due to loss of differential pressure as a result of a solenoid failure.

Susquehanna Steam Electric Station Unit 1
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 51830	10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material
3872016002R00 - NRC Website

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to 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.

CONDITIONS PRIOR TO EVENT

Unit 1 — Mode 5, 0 percent Rated Thermal Power Unit 2 — Mode 1, 100 percent Rated Thermal Power There were no other structures, systems, or components that were inoperable at the start of the event that contributed to the event.

EVENT DESCRIPTION

On March 29, 2016 at approximately 2256 hours0.0261 days <br />0.627 hours <br />0.00373 weeks <br />8.58408e-4 months <br />, SSES Unit 2 Zone II Secondary Containment [EIIS System Code: VA] dP was not maintained above the TS SR required value of 0.25 in. w.g. as a result of the "B" Equipment Compartment Exhaust Fan Discharge Damper, HD27521B, [EllS Component Code: DMP] closure and subsequent trip of the reactor building exhaust fan, 2V206B [EIIS Component Code: FAN]. The Unit 1 and Unit 2 Secondary Containment systems were declared inoperable and Action Statement for TS 3.6.4.1 was entered. Secondary Containment dP was restored to greater than 0.25 in. w.g. at approximately 2321 hours0.0269 days <br />0.645 hours <br />0.00384 weeks <br />8.831405e-4 months <br />, following the start of the "A" reactor building exhaust fan, 2V206A.

On March 30, 2016, at 0213 hours0.00247 days <br />0.0592 hours <br />3.521825e-4 weeks <br />8.10465e-5 months <br />, this condition was reported (ENS#51830) in accordance with 10 CFR 50.72(b)(3)(v)(C) for an event or condition that, at the time of discovery, could have prevented the fulfillment of the safety function. 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 that could have prevented the fulfillment of the safety function of Secondary Containment to control the release of radioactive material.

CAUSE OF EVENT

The cause of the event was failure of solenoid valve, SV27521B, [EIIS Component Code: SOL] which controls the "B" Equipment Compartment Exhaust Fan Discharge Damper. The failed valve was disassembled, inspected, and found to be damaged. Failure analysis of the solenoid valve determined the issue to be related to vendor parts quality.

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to 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.

ANALYSIS/SAFETY SIGNIFICANCE

Technical Specification 3.6.4.1 Surveillance Requirement 3.6.4.1.1 requires that secondary containment vacuum is maintained greater than or equal to 0.25 in. w.g. This event is being reported pursuant to 10 CFR 50.73(a)(2)(v)(C), as a loss of Secondary Containment differential pressure results in a condition that could have prevented fulfillment of a safety function to mitigate the consequences of an accident by controlling the release of radioactive material.

There was no actual safety consequence as a result of this event. Engineering analysis of this event has determined that secondary containment could have performed its safety function of isolating, as assumed in the accident analysis, and also of re-establishing 0.25 in. w.g. vacuum (drawdown) within the assumed accident analysis time (10 minutes). Therefore, the subject event did not cause a loss of safety function.

This event will not be counted as a safety system functional failure (SSFF) for the NRC performance indicator based on the Engineering analysis supporting the system's ability to fulfill the safety function.

CORRECTIVE ACTIONS

Corrective actions for this event include revision of the PM scope for Reactor Building HVAC solenoid valves and evaluation of a more robust solenoid valve for Reactor Building HVAC system.

COMPONENT INFORMATION

Manufacturer: ASCO Services Type: 3-way electrical solenoid valve Process Fluid: Air Model: ASCO 8320 Solenoid Valve, General Use Model 8320G003 Voltage: 120 VAC

PREVIOUS SIMILAR EVENTS

Docket No. 50-387, PLA 7437, LER 2015-013-00 "Loss of Differential Pressure in Zone I of Secondary Containment Due to Solenoid Valve Failure." Dated February 2, 2016.

Docket No. 50-387, PLA 7329, LER 2015-002-00 "Secondary Containment Inoperability Due to Failure to Meet Technical Specification Surveillance Requirement 3.6.4.1." Dated June 10, 2015.