|Reporting criterion:||10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material|
|ENS 52844||10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material|
|3882017006R00 - NRC Website|
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by 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 1, approximately 100 percent Rated Thermal Power Unit 2 — Mode 1, approximately 100 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
On July 10, 2017, at approximately0250 hours
, Reactor Building [EIIS System Code: NG] Zone II differential pressure was not maintained above the Technical Specification (TS) limit of 0.25 inch of vacuum water gauge (WG) due to Discharge Damper PDD27578B [EIIS System/Component Identifier: VA/DMP] failing closed resulting in loss of the associated Reactor Building Zone II Exhaust Fan 2V205B [EIIS System/Component Identifier: VA/FAN]. Reactor Building Zone II Exhaust Fan 2V205A was manually started and Reactor Building Zone II differential pressure was restored to greater than 0.25 inches WG by approximately0301 hours
. On July 10, 2017, at0735 hours
, this condition was reported (ENS #52844) in accordance with 10 CFR 50.72(b)(3)(v)(C) as an event or condition that, at the time of discovery, could have prevented the fulfillment of the safety function to mitigate the consequences of an accident by controlling the release of radioactive material. SSES has no redundant Secondary Containment System.
CAUSE OF EVENT
The cause of the event was the failure of an ASCO solenoid valve [EIIS Component Identifier: FSV] associated with Discharge Damper PDD27578B. Based on further review, the ASCO solenoid valve has been determined to be less than adequate for its application in Reactor Building Heating Ventilation and Air Conditioning (HVAC) system.
Based on engineering analysis of the event, secondary containment could have performed its safety function of isolating as assumed in the accident analysis and of re-establishing 0.25 inches of vacuum WG (drawdown) within the assumed accident analysis time (10 minutes).
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.
Estima!ed burden per response to comply with this mandatory collection request:80 hours
. Reported comments regarding burden estimate to the Information Services Branch (r.2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.Resource@nrc.gov, arid to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104). Office of Management arid Budget, Washington, DC 20503. If a means used to impose an information collection does riot 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 2017 -006 - 00
Key corrective actions include replacement of the failed solenoid valve with a more robust model.
COMPONENT FAILURE INFORMATION
ASCO Services 3-way electrical solenoid valve Air ASCO 8320 Solenoid Valve, General Use Model 8320G003 120 VAC
PREVIOUS SIMILAR EVENTS
The following are recent LERs involving loss of secondary containment due to component failures:
Exhaust Fan," dated August 18, 2017.
Supply Plenum Screens," dated February 2, 2016.
June 10, 2015.