05000388/LER-2015-006
| 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 51269 | 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material |
| 3882015006R00 - NRC Website | |
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 Monday, July 27, 2015 at 1118, Secondary Containment [ENS System Identifier: NG] became inoperable requiring a Technical Specification 3.6.4.1 entry for failure to meet Surveillance Requirement (SR) 3.6.4.1.1 on Unit 1 and Unit 2. The inoperability was caused by Zone 2 differential pressure lowering to less than 0.25 inches water column (WC) when a secondary containment door [ENS Component Identifier: DR] was opened without appropriate authorization. The secondary containment door was closed at 1149 and secondary containment differential pressure was verified to be greater than 0.25 inches WC at 1205.
Details concerning the events that occurred on July 27, 2015 are provided below (estimated times are marked with an asterisk):
0952* An electrician obtained a key from Security to access the reactor building roof (RBR). The travel route to the roof was not specified.
1000* Electricians obtained a Health Physics (HP) brief to access the RBR. The brief directed electricians to access the RBR via the stairwell (a route that breaches secondary containment) based on dose considerations. The normal route for performing maintenance on the RBR was through the control structure (a route that does not breach secondary containment).
1050* The electricians arrived at Door 104-R. Three signs were on the door: (1) SECONDARY CONTAIMENT BOUNDARY DOOR. DO NOT OPEN WITHOUT SHIFT SUPERVISION PERMISSION, (2) FOR ACCESS CONTACT SECURITY AT 3114/3115, and (3) RCA BOUNDARY NOTIFY HP PRIOR TO USE.
1055* The powered phones had poor service, so one of the electricians contacted a peer in the maintenance shop to contact Security and Operations for permission to access the RBR through the 104-R door. At no time during this conversation was it mentioned that the 104-R Door is a Secondary Containment Door.
1100* The peer contacted Security and the Operations Unit Supervisor (US) and obtained permission to access the RBR. During the conversation with Security, the electricians told security they were going on the roof to fix a camera. Security assumed they were going through the normal path which is through the control structure. During the conversation between the peer and the Control Room, the US was distracted and only focused on the reactor elevation and did not hear the 104-R Door reference. On the repeat back, the peer corrected the US and stated access would be through the 104-R Door. As a result, the US repeated back the message, but assumed they were going to access the RBR though the normal route (through the Control Structure). The US wanted to know why the Control Room was being called as the caller (the peer) seemed confused. The US explained that at no time during the call was a mention made of going through a Secondary Containment Boundary door. In addition, the US did not look up the 104-R Door in the plant component data system.
1107 The electricians passed through Door 104-R, unlocked the RBR Hatch and gained access to the roof.
1107 The Security Central Alarm Station (CAS) received a tamper alarm and dispatched a patrol to the alarm area.
1108 Security reviewed the applicable procedure to determine compensatory requirements for the alarm.
1110 Security contacted a maintenance leader in the shop and requested that the electricians on the roof call Security.
1111 The electricians on the RBR contacted Security to discuss work details.
1118 The Control Room received a Reactor Building HVAC Trouble alarm. The Control Room entered ON-RBHVAC-201 and Technical Specification 3.6.4.1 for both units due to secondary containment being inoperable.
1139 Security contacted the control room Shift Manager (SM) of receipt of the tamper alarm from RBR hatch. The SM advised Security to pull the electricians off the RBR.
1145 Security notified the electricians to leave the RBR immediately.
1151 The electricians left the RBR. Security closed the hatch and exited through Door 104-R.
1205 Operations exited Technical Specification 3.6.4.1 and the off-normal procedure (ON-RBHVAC-201).
This event was reported under 10 CFR 50.72(b)(3)(v) per the guidance of NUREG 1022, Revision 3, Section 3.2.7. An ENS notification was made on July 27th, 2015 under event number 51269. This event is also being reported as a Licensee Event Report (LER) in accordance with 10 CFR 50.73(a)(2)(v)(C).
CAUSE OF EVENT
The apparent cause is that the US failed to follow the standard to verify the impacts of opening the 104-R door. The causal factor was that multiple work groups displayed a less than adequate questioning attitude and use of three-way communication.
ANALYSIS/SAFETY SIGNIFICANCE
Susquehanna failed to maintain Secondary Containment at a minimum negative pressure of less than 0.25 inches vacuum WC and entered Technical Specification 3.6.4.1. This event is reportable under 10 CFR 50.72(b)(3)(v)(c) and 10 CFR 50.73(a)(2)(v)(C) as a loss of a Safety Function. There is no redundant Susquehanna Secondary Containment system.
During accident conditions, failure to maintain Secondary Containment could have resulted in a ground level release of airborne radioactive materials to the public. However, both Units were in Mode 1 at full power and there were no accident conditions present at the time the hatch was open.
CORRECTIVE ACTIONS
1. Add into GET Training "Why" maintaining Secondary Containment and Ventilation Boundaries are important to protecting the health and safety of the public and workers.
2. Update the "Routine Task Preventive Maintenance" (RTPM) to support emergent security intrusion detection equipment and repairs to include a Cautionary Note to use the Control Structure to access the RBR when such a need arises.
3. Develop and publish a station communication detailing "Why" maintaining Secondary Containment and Ventilation Boundaries are important to protecting the health and safety of the public and workers.
4. Security to change out the lock to Door 104-R so that the lock differs from the lock to access the RBR via the Control Structure side. The Key for 104-R will be a "Controlled" Key maintained by the Shift Manager.
5. Coach SRO involved in this event as to proper verification practices, 3 part communications and a proper questioning attitude.
COMPONENT FAILURE INFORMATION
There was no failed component.
PREVIOUS SIMILAR EVENTS
The following are recent LERs involving loss of secondary containment due to door issues:
Found Ajar," dated June 25, 2015.
Surveillance Requirement 3.6.4.1.1," dated May 11, 2015.
Personnel Error Resulting in Entry into Secondary Containment Technical Specification Limiting Condition for Operation," dated December 31, 2014.