05000220/LER-2016-001

LER-2016-001, Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors

Nine Mile Point Unit 1
Event date:	06-01-2016
Report date:	07-12-2016
Reporting criterion:	10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
2202016001R00 - NRC Website

LER 16-001-00 for Nine Mile Point Nuclear Station Unit 1 Regarding Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors

ML16202A148
Person / Time
Site:	Nine Mile Point
Issue date:	07/12/2016
From:	Kreider R E Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L 3093 LER 16-001-00
Download: ML16202A148 (7)

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.

05000-220

3. LER NUMBER

2016 - 00

A. PRE-EVENT PLANT CONDITIONS:

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

B. EVENT:

On Wednesday June 1, 2016, at approximately 1046, the secondary containment of the Unit 1 Reactor Building was breached when workers opened both airlock doors on elevation 261 simultaneously. The integrity of the airlock was re-established within 5 seconds when one of the doors was closed and latched.

During the event, two groups of individuals were attempting to use the Unit 1 airlock doors D-52 and D-53 simultaneously while exiting the Reactor Building. The cause of this event is personal accountability. With clear understanding of the expectations for using the airlock doors in conjunction with all mechanical barriers (lights, buzzers, monitors) functioning properly, the individual failed to use human performance tools to verify the airlock was not already being used by other individuals.

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.. This event represents a potential loss of secondary containment safety function as presented in Technical Specification 3.4.3, Access Control. This condition 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.

Nine Mile Point Unit 2 (NMP2) was unaffected by both airlock doors being open at NMP1.

The event has been entered into the plant's corrective action program as IR 2676493.

THE EVENT:

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

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.

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES AND OPERATOR ACTIONS:

The dates, times, and major occurrences and operator actions for this event are as follows. All dates are 2016.

June 1 1046 Individual 1 had entered the airlock via door D-53 (inner door) and was in the process of exiting the airlock via door D-52 (outer door).

1046 Without verifying on the monitors that other personnel were either in the airlock or attempting to enter the airlock through the opposing door D-52, Individual 2 opened door D-53 while Individual 1 was opening door D-52.

1046 Upon the realization that both doors had been breached simultaneously, the doors were immediately (less than 5 seconds) closed re-establishing containment integrity.

During the time both doors are open, NMP1 Limiting Condition of Operation 3.4.3 is not met.

E. METHOD OF DISCOVERY:

This event was self-identified by station personnel traversing the Reactor Building airlock doors.

F. SAFETY SYSTEM RESPONSES:

The duration of the event was 5 seconds, or less. 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. Operators entered the applicable TS action statement then exited it soon afterwards. The event concluded when the airlock door was shut.

II. CAUSE OF EVENT:

The cause of this event is personal accountability. With clear understanding of the expectations for using the airlock doors in conjunction with all mechanical barriers (lights, buzzers, monitors) functioning properly, the individual failed to use human performance tools to verify the airlock was not already being used by other individuals.

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 intemet 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.

05000-220

3. LER NUMBER

2016 - 00

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 determined the 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:

Airlock doors were closed and secondary containment was restored to Operable status.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

In accordance with station policies and procedures, Performance Management was applied to the individual who failed to use their human performance- tools resulting in both airlock doors being opened simultaneously.

A. FAILED COMPONENTS:

There were no 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.

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 intemet 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.

NMP1 LER 2015-003, August 5, 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 5 seconds, or less, when one of the doors was closed and latched.

Secondary Containment differential pressure was unaffected by these events.

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

COMPONENT

IEEE 803 FUNCTION IEEE 805 SYSTEM

IDENTIFIER IDENTIFICATION

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

D. SPECIAL COMMENTS:

None