05000220/LER-2014-005, Regarding Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors

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Regarding Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors
ML14353A213
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 12/12/2014
From: Orphanos P
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NMP1L 2977 LER 14-005-00
Download: ML14353A213 (13)
v • d • e


LER-2014-005, Regarding Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(viii)(B)
10 CFR 50.73(a)(2)(iii)
10 CFR 50.73(a)(2)(ix)(A)
10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2202014005R00 - NRC Website
v • d • e

text

Addomw AANNOW AMENPIF Exe!on Generation.

10 CFR 50.73 NMP1L 2977 December 12, 2014 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-63 NRC Docket No. 50-220

Subject:

NMP1 Licensee Event Reports 2014-005 and 2014-006, Secondary Containment Inoperable due to Simultaneous Opening of Airlock Doors In accordance with the reporting requirements contained in 10 CFR 50.73(a)(2)(v)(C), please find attached NMP1 Licensee Event Reports 2014-005 and 2014-006, Secondary Containment Inoperable due to Simultaneous Opening of Airlock Doors.

There are no regulatory commitments contained in this letter.

Should you have any questions regarding the information in this submittal, please contact Terry F. Syrell, Acting Manager Site Regulatory Assurance, at (315) 349-5245.

Sincerely, 0 -1p i" e:,111 1111110..,

Peter M. Orphanos Plant Manager, Nine Mile Point Nuclear Station Attachments:

1. NMP1 Licensee Event Report 2014-005, Secondary Containment Inoperable due to Simultaneous Opening of Airlock Doors
2. NMP1 Licensee Event Report 2014-006, Secondary Containment Inoperable due to Simultaneous Opening of Airlock Doors cc:

NRC Regional Administrator, Region I NRC Resident Inspector NRC Project Manager coU-NMP1 Licensee Event Report 2014-005, Secondary Containment Inoperable due to Simultaneous Opening of Airlock Doors Nine Mile Point Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-63

NitC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send 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 LICENSEE EVENT REPORT (LER) internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of 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 digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Nine Mile Point Unit 1 05000220 1 OF 5
4. TITLE Secondary Containment Inoperable Due to Simultaneous Opening of Airlock Doors
5. EVENT DATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED Ir I'FACrLTYNAME DOKTNME MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR I

N/A N/A FACILITY NAME DOCKET NUMBER 10 16 2014 2014-005

- 00 12 12 12014 IN/A N/A
9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

El 20.2201(b)

[I 20.2203(a)(3)(i)

El 50.73(a)(2)(i)(C)

[E 50.73(a)(2)(vii)

[-

20.2201(d)

El 20.2203(a)(3)(ii)

[I 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

El 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B)

El 20.2203(a)(2)(i)

[I 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL El 20.2203(a)(2)(ii)

[_

50.36(c)(1)(ii)(A)

El 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

El 20.2203(a)(2)(iii)

[-

50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71 (a)(4)

El 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

[E 50.73(a)(2)(v)(B)

El 73.71 (a)(5) 100%

20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)

El OTHER

[] 20.2203(a)(2)(vi)

El 50.73(a)(2)(i)(B)

El 50.73(a)(2)(v)(D)

Specify in Abstract below or in

1. DESCRIPTION OF EVENT

A. PRE-EVENT PLANT CONDITIONS:

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

B. EVENT:

On October 16, 2014 at approximately 1042, Reactor Building airlock doors were opened simultaneously. NMP1 was operating at rated thermal power. The incident occurred during normal egress from the reactor building into the turbine building. From review of the Badge Access Transaction Report in addition to personnel statements from the prompt investigation, the following scenario had occurred resulting in the event:

Three workers approached door D-053 (inner door) to exit the Reactor Building. At the same time, two other workers approached door D-052 (outer door) to enter the Reactor Building. Per site expectations, both groups waited for 5 seconds, ensured the green light was activated, verified no door alarm was sounding, and then opened their respective doors. Both doors opened simultaneously resulting in a breach of the secondary containment. Inner door D-053 was immediately closed terminating the breach and re-establishing secondary containment integrity.

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 2396495.

C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

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

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES

The dates, times and major occurrences for this event are as follows:

October 16, 2014 1042 Workers carded in D-053 (inner door)

Secondary containment was breached when D-052 (outer door) was opened simultaneously.

D-053 (inner door) is shut Entered TS action statement 3.4.3, Condition C and exited.

E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED

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

F. METHOD OF DISCOVERY

This event was discovered by station personnel reporting the issue.

G. MAJOR OPERATOR ACTION:

NMP1 entered TS action statement 3.4.3, and exited it when the inner door was shut.

H. SAFETY SYSTEM RESPONSES:

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. Operators entered the applicable TS action statement then exited it soon afterwards. The event concluded when the inner airlock door was shut.

I1. CAUSE OF EVENT:

The cause of the event is an inherent vendor design issue that was not known resulting in a false expectation that the magnetic locks would prevent simultaneous opening of the airlocks.

II1. 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). It is defined under paragraph 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 differential pressure was unaffected by this event.

The primary access to the NMP1 Reactor Building is through the airlock doors D-052 and D-053. In response to the event, the station entered the action statement for TS 3.4.3 then promptly exited it when the airlock doors were shut. Computer data identified that secondary containment differential pressure was unaffected by this event. 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. 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. 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 unit has three secondary containment airlocks. Temporary cameras and monitors have been installed at two of the airlocks. These two airlocks were selected based on high amount of usage / personnel traffic they are subjected to.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Corrective actions to be taken include installing cameras and monitors to prevent breaching of the secondary containment.

Cameras will be installed inside the two high traffic airlocks due to personnel inside the airlock not being observable. The cameras inside the airlocks will transmit to each of the monitors on the outside of the airlock to verify no one is inside prior to proceeding.

V. ADDITIONAL INFORMATION

A. FAILED COMPONENTS:

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

B. PREVIOUS LERs ON SIMILAR EVENTS:

NMP1 LER 2014-004. On August 13, 2014, at approximately 2318 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.81999e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:

IEEE 803 FUNCTION IDENTIFIER IEEE 805 SYSTEM IDENTIFICATION COMPONENT Reactor Building (BWR)

Reactor Building Ventilation System Airlock Door D. SPECIAL COMMENTS:

None N/A PDIC DR NG VA NG

1. DESCRIPTION OF EVENT

A. PRE-EVENT PLANT CONDITIONS:

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

B. EVENT:

On October 20, 2014 at approximately 1353, Reactor Building airlock doors were opened simultaneously. NMP1 was operating at rated thermal power. The incident occurred as personnel traversed through the airlock. From review of the Badge Access Transaction Report in addition to personnel statements from the prompt investigation, the following scenario had occurred resulting in the event:

First worker approached door D-052 (outer door) to enter the Reactor Building. At the same time, a second worker had already entered into the airlock through door D-052 and was preparing to enter into the Reactor Building through door D-053 (inner door). The first worker waited 5 seconds, ensured the green light was activated, and verified no door alarm was sounding and then badged into the door and opened door D-052. At the same time, the second worker inside the airlock (who had been in the airlock approximately 12 seconds) opened door D-053 in order to enter the Reactor Building. This concurrent opening of both airlock doors resulted in a breach of the secondary containment. One of the doors was immediately closed within 5 seconds re-establishing secondary containment integrity.

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 2398224.

C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

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

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES

The dates, times and major occurrences for this event are as follows:

October 20, 2014 1353 First carded in D-052 (inner door)

Secondary containment was breached when D-053 (outer door) was opened simultaneously.

One of the doors was immediately closed Entered TS action statement 3.4.3, Condition C and exited.

E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED

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

F. METHOD OF DISCOVERY

This event was discovered by station personnel reporting the issue.

G. MAJOR OPERATOR ACTION:

NMP1 entered TS action statement 3.4.3, and exited it when the inner door was shut.

H. SAFETY SYSTEM RESPONSES:

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. Operators entered the applicable TS action statement then exited it soon afterwards. The event concluded when the inner airlock door was shut.

I1. CAUSE OF EVENT:

The cause of the event is an inherent vendor design issue that was not known resulting in a false expectation that the magnetic locks would prevent simultaneous opening of the airlocks.

Ill. 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). It is defined under paragraph 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 differential pressure was unaffected by this event.

The primary access to the NMP1 Reactor Building is through the airlock doors D-052 and D-053. In response to the event, the station entered the action statement for TS 3.4.3 then promptly exited it when the airlock doors were shut. Computer data identified that secondary containment differential pressure was unaffected by this event. 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. 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. 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 unit has three secondary containment airlocks. Temporary cameras and monitors have been installed at two of the airlocks. These two airlocks were selected based on high amount of usage / personnel traffic they are subjected to.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Corrective actions to be taken include installing cameras and monitors to prevent breaching of the secondary containment.

Cameras will be installed inside the two high traffic airlocks due to personnel inside the airlock not being observable. The cameras inside the airlocks will transmit to each of the monitors on the outside of the airlock to verify no one is inside prior to proceeding.

V. ADDITIONAL INFORMATION

A. FAILED COMPONENTS:

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

B. PREVIOUS LERs ON SIMILAR EVENTS:

NMP1 LER 2014-004. On August 13, 2014, at approximately 2318 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.81999e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

NMP1 LER 2014-005. On October 16, 2014, at approximately 1042 hours0.0121 days <br />0.289 hours <br />0.00172 weeks <br />3.96481e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:

COMPONENT IEEE 803 FUNCTION IDENTIFIER IEEE 805 SYSTEM IDENTIFICATION Reactor Building (BWR)

Reactor Building Ventilation System Airlock Door D. SPECIAL COMMENTS:

None N/A PDIC DR NG VA NG

1. DESCRIPTION OF EVENT

A. PRE-EVENT PLANT CONDITIONS:

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

B. EVENT:

On October 16, 2014 at approximately 1042, Reactor Building airlock doors were opened simultaneously. NMP1 was operating at rated thermal power. The incident occurred during normal egress from the reactor building into the turbine building. From review of the Badge Access Transaction Report in addition to personnel statements from the prompt investigation, the following scenario had occurred resulting in the event:

Three workers approached door D-053 (inner door) to exit the Reactor Building. At the same time, two other workers approached door D-052 (outer door) to enter the Reactor Building. Per site expectations, both groups waited for 5 seconds, ensured the green light was activated, verified no door alarm was sounding, and then opened their respective doors. Both doors opened simultaneously resulting in a breach of the secondary containment. Inner door D-053 was immediately closed terminating the breach and re-establishing secondary containment integrity.

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 2396495.

C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

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

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES

The dates, times and major occurrences for this event are as follows:

October 16, 2014 1042 Workers carded in D-053 (inner door)

Secondary containment was breached when D-052 (outer door) was opened simultaneously.

D-053 (inner door) is shut Entered TS action statement 3.4.3, Condition C and exited.

E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED

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

F. METHOD OF DISCOVERY

This event was discovered by station personnel reporting the issue.

G. MAJOR OPERATOR ACTION:

NMP1 entered TS action statement 3.4.3, and exited it when the inner door was shut.

H. SAFETY SYSTEM RESPONSES:

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. Operators entered the applicable TS action statement then exited it soon afterwards. The event concluded when the inner airlock door was shut.

I1. CAUSE OF EVENT:

The cause of the event is an inherent vendor design issue that was not known resulting in a false expectation that the magnetic locks would prevent simultaneous opening of the airlocks.

II1. 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). It is defined under paragraph 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 differential pressure was unaffected by this event.

The primary access to the NMP1 Reactor Building is through the airlock doors D-052 and D-053. In response to the event, the station entered the action statement for TS 3.4.3 then promptly exited it when the airlock doors were shut. Computer data identified that secondary containment differential pressure was unaffected by this event. 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. 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. 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 unit has three secondary containment airlocks. Temporary cameras and monitors have been installed at two of the airlocks. These two airlocks were selected based on high amount of usage / personnel traffic they are subjected to.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Corrective actions to be taken include installing cameras and monitors to prevent breaching of the secondary containment.

Cameras will be installed inside the two high traffic airlocks due to personnel inside the airlock not being observable. The cameras inside the airlocks will transmit to each of the monitors on the outside of the airlock to verify no one is inside prior to proceeding.

V. ADDITIONAL INFORMATION

A. FAILED COMPONENTS:

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

B. PREVIOUS LERs ON SIMILAR EVENTS:

NMP1 LER 2014-004. On August 13, 2014, at approximately 2318 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.81999e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:

IEEE 803 FUNCTION IDENTIFIER IEEE 805 SYSTEM IDENTIFICATION COMPONENT Reactor Building (BWR)

Reactor Building Ventilation System Airlock Door D. SPECIAL COMMENTS:

None N/A PDIC DR NG VA NG

1. DESCRIPTION OF EVENT

A. PRE-EVENT PLANT CONDITIONS:

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

B. EVENT:

On October 20, 2014 at approximately 1353, Reactor Building airlock doors were opened simultaneously. NMP1 was operating at rated thermal power. The incident occurred as personnel traversed through the airlock. From review of the Badge Access Transaction Report in addition to personnel statements from the prompt investigation, the following scenario had occurred resulting in the event:

First worker approached door D-052 (outer door) to enter the Reactor Building. At the same time, a second worker had already entered into the airlock through door D-052 and was preparing to enter into the Reactor Building through door D-053 (inner door). The first worker waited 5 seconds, ensured the green light was activated, and verified no door alarm was sounding and then badged into the door and opened door D-052. At the same time, the second worker inside the airlock (who had been in the airlock approximately 12 seconds) opened door D-053 in order to enter the Reactor Building. This concurrent opening of both airlock doors resulted in a breach of the secondary containment. One of the doors was immediately closed within 5 seconds re-establishing secondary containment integrity.

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 2398224.

C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

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

D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES

The dates, times and major occurrences for this event are as follows:

October 20, 2014 1353 First carded in D-052 (inner door)

Secondary containment was breached when D-053 (outer door) was opened simultaneously.

One of the doors was immediately closed Entered TS action statement 3.4.3, Condition C and exited.

E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED

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

F. METHOD OF DISCOVERY

This event was discovered by station personnel reporting the issue.

G. MAJOR OPERATOR ACTION:

NMP1 entered TS action statement 3.4.3, and exited it when the inner door was shut.

H. SAFETY SYSTEM RESPONSES:

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. Operators entered the applicable TS action statement then exited it soon afterwards. The event concluded when the inner airlock door was shut.

I1. CAUSE OF EVENT:

The cause of the event is an inherent vendor design issue that was not known resulting in a false expectation that the magnetic locks would prevent simultaneous opening of the airlocks.

Ill. 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). It is defined under paragraph 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 differential pressure was unaffected by this event.

The primary access to the NMP1 Reactor Building is through the airlock doors D-052 and D-053. In response to the event, the station entered the action statement for TS 3.4.3 then promptly exited it when the airlock doors were shut. Computer data identified that secondary containment differential pressure was unaffected by this event. 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. 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. 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 unit has three secondary containment airlocks. Temporary cameras and monitors have been installed at two of the airlocks. These two airlocks were selected based on high amount of usage / personnel traffic they are subjected to.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

Corrective actions to be taken include installing cameras and monitors to prevent breaching of the secondary containment.

Cameras will be installed inside the two high traffic airlocks due to personnel inside the airlock not being observable. The cameras inside the airlocks will transmit to each of the monitors on the outside of the airlock to verify no one is inside prior to proceeding.

V. ADDITIONAL INFORMATION

A. FAILED COMPONENTS:

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

B. PREVIOUS LERs ON SIMILAR EVENTS:

NMP1 LER 2014-004. On August 13, 2014, at approximately 2318 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.81999e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

NMP1 LER 2014-005. On October 16, 2014, at approximately 1042 hours0.0121 days <br />0.289 hours <br />0.00172 weeks <br />3.96481e-4 months <br />, the secondary containment of the Nine Mile Point Unit 1 (NMP1) Reactor Building was breached when workers opened both inner (D053) and outer (D052) airlock doors, simultaneously while passing through. The integrity of the airlock was re-established approximately 5 seconds when one of the doors was closed and latched. Secondary Containment differential pressure was unaffected by this event.

C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:

COMPONENT IEEE 803 FUNCTION IDENTIFIER IEEE 805 SYSTEM IDENTIFICATION Reactor Building (BWR)

Reactor Building Ventilation System Airlock Door D. SPECIAL COMMENTS:

None N/A PDIC DR NG VA NG

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