05000388/LER-2014-001
| Susquehanna Steam Electric Station, Unit 2 | |
| Event date: | |
|---|---|
| Report date: | |
| Initial Reporting | |
| ENS 50595 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material |
| 3882014001R00 - NRC Website | |
20555-0001, or by internet e-mail to Infocollects.Resource©nrc.gov, and to 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 EVENT
Unit 1 — Mode 1, 100 percent Rated Thermal Power Unit 2 — Mode 1, 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.
EVENT DESCRIPTION
On November 5, 2014 at 1115 hours0.0129 days <br />0.31 hours <br />0.00184 weeks <br />4.242575e-4 months <br />, Secondary Containment Zone 3 (Unit 1 & 2 Reactor Building [EIIS System Identifier: NG]) was unintentionally cross tied to Secondary Containment Zone 2 (Unit 2 Reactor Building) for approximately two seconds during passage of personnel through a personnel airlock [EIIS Component Identifier: AL]. Secondary Containment Zone 2 and Zone 3 ventilation [EIIS System Identifier:
VA] remained in service and stable.
Limiting Condition for Operation (LCO) 3.6.4.1 was entered and exited based on the prohibited crosstie of Secondary Containment Zones. Technical Specification Secondary Containment Operability requires that at least one door [EIIS Component Identifier: DR] remain closed for airlocks where two doors are provided when an access opening between Secondary Containment Zones is being used for exit and entry.
This event was reported under 10 CFR 50.72(b)(3)(v)(C) and per the guidance of NUREG 1022, Revision 3, Section 3.2.7 as a loss of a safety function (EN 50595). There is no redundant Susquehanna Secondary Containment System.
Details of the investigation of the event are as follows:
A Non-Licensed Operator (NLO) was performing equipment checks in the Unit 2 Reactor Building.
Following completion of the equipment checks, the NLO approached Door DR-115R to egress through Airlock 11-606. The NLO unlatched Door DR-115R prior to verifying the airlock was clear and that conditions were met for opening the door. During an interview, the NLO stated that at the moment he unlatched the door, he noticed the red light [EIIS Component Identifier: IL] was illuminated, indicating the opposite airlock door was not latched and conditions were not met for passage through Door DR-115R. The NLO immediately reclosed and latched Door DR-115R, restoring the airlock and separation of Secondary Containment Zones 2 and 3. After reclosing and latching Door DR-115R, the NLO confirmed that personnel passed through the airlock and had not yet closed and latched the opposite door at the time he unlatched door DR-115R. The NLO immediately notified the Control Room and submitted a condition report to document the event.
The NLO stated that he did not focus on verifying airlock conditions prior to unlatching Door DR-115R.
CAUSE OF EVENT
The cause of the event was human performance error in that a self-check was not performed prior to opening the airlock door.
ANALYSIS/SAFETY SIGNIFICANCE
The actual consequence was inadvertent, prohibited crosstie of Secondary Containment Zones 2 and 3 requiring momentary entry into LCO 3.6.4.1 and an eight hour notification of the event to the Nuclear Regulatory Commission (NRC).
An engineering evaluation was performed and concluded that secondary containment could have performed its safety function of isolating as assumed in the accident analysis and also of re-establishing 0.25 inches 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 that shows there was no loss of ability to fulfill the safety function.
CORRECTIVE ACTIONS
The on-shift Shift Manager coached the NLO on the importance of self-check for verifying conditions are met prior to passage through a Secondary Containment airlock door.
A communication to all station personnel will be distributed reinforcing the significance of secondary containment airlocks, the conditions required for passage through an airlock, and how to verify these conditions. The communication will also highlight the need for personnel to verify that the opposite door is closed first and, if possible, locked in position before entering or exiting a personnel airlock (PAL).
PREVIOUS SIMILAR EVENTS
No previous similar events were identified.