05000220/LER-2015-003

LER-2015-003, Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors

Nine Mile Point Unit 1
Event date:	8-5-2015
Report date:	10-2-2015
Reporting criterion:	10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
2202015003R00 - NRC Website

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A. PRE-EVENT PLANT CONDITIONS:

Prior to the event, Nine Mile Point Nuclear Station Unit 1 (NMP1) was operating at 100% power.

B. EVENT:

On Wednesday August 5, 2015 at approximately 1252 hours0.0145 days <br />0.348 hours <br />0.00207 weeks <br />4.76386e-4 months <br />, both Unit 1 Reactor Building Airlock Doors on the 261 foot elevation were opened simultaneously, resulting in a momentary loss of Secondary Containment Operability. Upon identification, the doors were immediately closed and operability was restored. The incident occurred as personnel traversed through the airlock.

The event occurred while two personnel were in the airlock, exiting the Reactor Building into the Turbine Building, when another individual attempted to catch up to them and opened the inner door on the Reactor Building side of the airlock just as they were opening the outer door on the Turbine Building side of the airlock. Both doors were immediately shut and the control room notified.

Operations review determined that the simultaneous opening of both secondary containment airlock doors constituted a momentary loss of secondary containment per Technical Specification 3.4.3 and NUREG 1022, Revision 3.

Review of the Reactor Building differential pressure as recorded by the plant process computer for the time period of the event indicated that the actual differential pressure remained negative and was unaffected by the brief simultaneous opening of the airlock doors.

This event has been documented in the plant's corrective action program as IR 2538089.

TO THE EVENT:

No other systems, structures, or components contributed to this event.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

No other systems or secondary functions were affected beyond the systems discussed in Section I.B.

a ' LICENSEE EVENT REPORT (LER)

E. METHOD OF DISCOVERY:

This event was discovered by station personnel reporting the issue.

F. SAFETY SYSTEM RESPONSES:

There were no safety system responses as a result of the event. The duration of this event was approximately 5 seconds. Review of the Reactor Building differential pressure as recorded by the plant process computer for the time period of the event indicated that the actual differential pressure remained negative and was unaffected by the brief simultaneous opening of the airlock doors.

II. CAUSE OF EVENT:

Clear and well-advertised barriers for passage through the air lock doors were not followed.

The single worker entering from the Reactor Building side had opened his door intentionally in an attempt to get into the airlock while personnel were inside. Contrary to site expectations and administrative postings on the door, the worker on the Reactor Building side did not pause for five seconds and wait for the personnel who were inside the airlock to exit.

III. ANALYSIS OF THE EVENT:

Simultaneous opening of both reactor building airlock doors is reportable under 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.73(a)(2)(v)(C) as 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.

Secondary containment structural integrity, the ability to automatically isolate the non-safety related Reactor Building ventilation system, and the Reactor Building Emergency Ventilation System availability were not impacted by the event. It is concluded that the safety significance of this event is low and the event did not pose a threat to the health and safety of the public or plant personnel.

The analysis of the event safety function was not prevented from being fulfilled, the occurrence is not considered a safety system functional failure. This event does not affect the NRC Regulatory Oversight Process Indicators.

IV. CORRECTIVE ACTIONS:

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL

STATUS:

The RB 261 foot elevation airlock doors were shut.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Disciplinary action was administered for the individual entering the airlock from the Reactor Building side.

A. FAILED COMPONENTS:

There were no other failed components that contributed to this event.

B. PREVIOUS LERs ON SIMILAR EVENTS:

NMP1 LER 2014-004, August 13, 2014.

NMP1 LER 2014-005, October 16, 2014.

NMP1 LER 2014-006, October 20, 2014.

NMP1 LER 2015-001, February 11, 2015.

NMP1 LER 2015-002, March 3, 2015.

(NMP1) Reactor Building was breached when workers opened both inner and outer airlock doors simultaneously while passing through. The integrity of the airlock was re-established within approximately 5 seconds when one of the doors was closed and latched.

Secondary Containment differential pressure was unaffected by these events.

The three LERs in 2014 occurred at the main airlock into the RB 261 foot elevation. The two previous LERs in 2015 were for simultaneous opening of the airlock doors on the RB 340 foot elevation.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION

TO IN THIS LER:

IEEE 803 FUNCTION IEEE 805 SYSTEM

IDENTIFIER IDENTIFICATION COMPONENT

Reactor Building (BWR) N/A NG Reactor Building Ventilation System PDIC VA Airlock Door DR NG

D. SPECIAL COMMENTS:

None