NG-15-0236, LERs 15-001-01 and 15-003-01 for Duane Arnold Regarding Both Doors in Secondary Containment Airlock Opened Concurrently

LERs 15-001-01 and 15-003-01 for Duane Arnold Regarding Both Doors in Secondary Containment Airlock Opened Concurrently

ML15181A336
Person / Time
Site:	Duane Arnold
Issue date:	06/25/2015
From:	Vehec T NextEra Energy Duane Arnold
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NG-15-0236 LER 15-001-01, LER 15-003-01
Download: ML15181A336 (7)

Text

NExTera ENER :Y June 25, 2015 NG-1 5-0236 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Duane Arnold Energy Center Docket 50-331 Renewed Op. License No. DPR-49 Licensee Event Reports #2015-001-01 and #2015-003-01 Please find attached the subject reports submitted in accordance with 10 CFR 50.73. This letter makes no new commitments or changes to any existing commitments.

T. A. Vehec Vice President, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC cc: Administrator, Region III, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA52324

NRC 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.

-W ,*Send comments regarding burden estimate to the FOIA, Privacy and Information Collections IEOBranch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEE EVENT fREPORT (LER) internet e-mail to Infocollects.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.

1. FACILITY NAME 2. DOCKET NUMBER 3. PAGE Duane Arnold Energy Center 05000-331 1 OF

4. TITLE Both Doors in Secondary Containment Airlock Opened Concurrently

5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED DOCKET NUMBER MONTH DAY YEAR YEAR YER SEQUENTIAL NUMBER NO.

REV MOT MD A ER N/A NAME FACILITY N/A IFACILITY NAME DOCKET NUMBER 03 21 2015 2015 - 001 - 01 06 25 2015 N/A N/A

9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

LI 20.2201(b) El 20.2203(a)(3)(i) [j 50.73(a)(2)(i)(C) [L 50.73(a)(2)(vii)

LI 20.2201(d) LI 20.2203(a)(3)(ii) LI 50.73(a)(2)(ii)(A) LI 50.73(a)(2)(viii)(A)

LI 20.2203(a)(1) LI 20.2203(a)(4) EL 50.73(a)(2)(ii)(B) LI 50.73(a)(2)(viit)(B)

LI 20.2203(a)(2)(i) LI 50.36(c)(1)(i)(A) LI 50.73(a)(2)(fii) LI 50.73(a)(2)(ix)(A)

10. POWER LEVEL LI 20.2203(a)(2)(ii) LI 50.36(c)(1)(ii)(A) LI 50.73(a)(2)(iv)(A) LI 50.73(a)(2)(x)

LI 20.2203(a)(2)(iii) LI 50.36(c)(2) EL 50.73(a)(2)(v)(A) LI 73.71 (a)(4)

L0 20.2203(a)(2)(iv) LI 50.46(a)(3)(ii) LI 50.73(a)(2)(v)(B) LI 73.71 (a)(5) 1 %20.2203(a)(2)(v) [L 50.73(a)(2)(i)(A) Z 50.73(a)(2)(v)(C) LI OTHER El 20.2203(a)(2)(vi) [] 50.73(a)(2)(i)(B) El 50.73(a)(2)(v)(D) Specify inAbstract below or in

12. LICENSEE CONTACT FOR THIS LER

-ICENSEE CONTACT (3L19H)NE 85o1e7 Laura B. Swenzinski, Senior Licensing Engineer I(319) 851-7724 NUMBER (IncludeArea

13. COMPLETE ONE LINE FOR EACH COMPONENT FAI CAUSE SYSTEM COMPONENT FMANU- REPORTABLE CAUSE FACTURER TO EPIX I X JM IEL Alarm Lock N N/A

14. SUPPLEMENTAL REPORT EXPECTED LI YES (If yes, complete 15. EXPECTED SUBMISSION DATE) Z NO ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spacedtypewritten lines)

On March 21, 2015, while operating at 100% power, workers opened doors concurrently when entering a secondary containment access airlock. The individuals involved each closed their respective doors upon encountering this unexpected condition; however, the result was a brief inoperability of secondary containment integrity. This resulted in an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event. The Resident Inspector was notified, and an Event Notification was made pursuant to 10 CFR 50.72(b)(3)(v)(C) due to a condition at the time of discovery that prevented the fulfillment of the Secondary Containment safety function (Reference EN#50914).

Following the event, the doors were verified to be functioning properly and no deficiencies were noted on either door.

A Root Cause Evaluation was conducted and determined the root cause of this event is that the airlock door interlock is not designed to prevent more than one airlock door from opening under all possible conditions.

This event did not result in a safety system functional failure. There were no radiological releases associated with this event.

NRC FORM 366 (02-2014)

NRC FORM 366A 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 FOLA,Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by L....

LIC INSEE EVENT REPORT (LER) LE Eand internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, CONTINUATION SHEET Washington, DC 20503. Ia 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.

1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGE Duane Arnold Energy Center 05000-331 INUMBER YEAR 2015 -

SEQUENTIAL 001 REV NO.

01 j 2 OF 3 NARRATIVE I. Description of Event:

On March 21, 2015 at 0030, while operating at 100% power, the Control Room Supervisor (CRS) received a call that Door 225 and Door 228, both in Secondary Containment Airlock 216 had been opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. The individuals involved immediately closed their respective doors upon encountering this unexpected condition. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status.

This resulted in an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event. The Resident Inspector was notified, and an Event Notification was made pursuant to 10 CFR 50.72(b)(3)(v)(C) due to a condition at the time of discovery that prevented the fulfillment of the Secondary Containment safety function (Reference EN#50914). Secondary containment leak tightness is required to ensure that the release of radioactive materials from the primary containment is restricted to those leakage paths and associated leakage rates assumed in the accident analysis and that fission products entrapped within the secondary containment structure will be treated by the Standby Gas Treatment System prior to discharge to the environment.

The Secondary Containment airlock utilizes an interlock device with an adjustable permanent magnet (mounted on the door), and an electromagnet (on the door frame) arranged in an electrical circuit so that door(s) are held closed and/or are allowed to open. Immediately following the event, the doors were verified to be functioning properly and no deficiencies were noted on either door. On March 22, 2015 at 1619 hours0.0187 days <br />0.45 hours <br />0.00268 weeks <br />6.160295e-4 months <br />, surveillance testing was performed satisfactorily per Surveillance Test Procedure (STP) 3.6.4.1-02, Secondary Containment Airlock Verification.

There were no radiological releases associated with this event. There were no other structures, systems or components inoperable at the start of this event that contributed to the event.

II. Assessment of Safety Consequences:

There were no actual safety consequences associated with this event; the potential safety consequences were minimal. Both doors on the airlock were open simultaneously for less than 10 seconds, and were able to close immediately upon discovery of the condition.

This event will not be reported as a safety system functional failure since an engineering analysis (Corrective Action ACE1968923-01) determined that the system is capable of performing its safety function during events when the airlock is open for less than 10 seconds. The post-LOCA dose calculation does not credit secondary containment integrity for mitigation of on-site and off-site doses for the first 5 minutes of the event. Therefore, this event is bounded by the existing dose calculation.

NRC FORM 366A (02-2014)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014) LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

1. FACILITY NAME 2. DOCKET 6. LER NUMBER j 3. PAGE IYEAR YEAR SEQUENTIAL NUMBER REV NO.

Duane Arnold Energy Center 05000-331 3 OF 3 2015 - 001 - 01 NARRATIVE This event did not result in a safety system functional failure. There were no automatically or manually initiated safety system responses.

Ill. Cause of Event:

Technical Specifications Surveillance Requirement SR 3.6.4.1.2 requires one inner or one outer secondary containment airlock door to be closed at all times. A Root Cause Evaluation was conducted and determined the root cause of this event is that the airlock door interlock is not designed to prevent more than one airlock door from opening under all possible conditions.

Specifically, the interlock may allow opening both doors in an airlock if both permissive buttons are depressed simultaneously.

IV. Corrective Actions:

An operational check of the Secondary Containment door interlocks is performed monthly via STP 3.6.4.1-02, Secondary Containment Airlock Verification. Additionally, signs have been installed at each airlock door instructing personnel who are accessing or leaving the airlock to wait 2 seconds after activating the interlock before opening the door. This corrective action introduces a time delay, which allows additional time for the interlock mechanism to actuate and prevent the other door from being opened. TSTF-551, "Revise Secondary Containment Surveillance Requirements" will be implemented once approved.

V. Additional Information:

Previous Similar Occurrences:

A review of DAEC Licensee Event Reports from the past 5 years identified three similar LER 2014-003.

occurrences, reference LER 2013-006, LER 2014-002 and A review of the corrective action program identified additional occurrences of airlock conditions causing momentary secondary containment inoperability - seven additional occurrences in the past two years, with five of those occurring in the last year.

EIIS System and Component Codes:

IEL Interlock Reportinq Requirements:

This event is being reported as an 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, 10CFR50.73(a)(2)(v)(C).

NRC FORM 366A (02-2014)

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

,., Estmated 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, Pdvacy and Information Collections LICENSEE EVENT REPORT (LER) TBranch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by (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 digits/characters for each block) 20503. If a means used to impose an information collection does not display a currently valid OMB g / ccontrol number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

1. FACILITY NAME 2. DOCKET NUMBER 3. PAGE Duane Arnold Energy Center 05000-331 1 OF 3

4. TITLE Both Doors in Secondary Containment Airlock Opened Concurrently

5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO. MONTH DAY YEAR N/A N/A FACILITY NAME DOCKET NUMBER 04 16 2015 2015 - 003 - 01 .06 25 2015 N/A N/A

9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

[Z 20.2201(b) LI 20.2203(a)(3)(i) .- 50.73(a)(2)(i)(C) LI 50.73(a)(2)(vii)

[_ 20.2201(d) LI 20.2203(a)(3)(ii) LI 50.73(a)(2)(ii)(A) LI 50.73(a)(2)(viii)(A)

[L 20.2203(a)(1) Li 20.2203(a)(4) LI 50.73(a)(2)(ii)(B) LI 50.73(a)(2)(viii)(B)

__ 20.2203(a)(2)(i) EL 50.36(c)(1)(i)(A) [i 50.73(a)(2)(iii) E] 50.73(a)(2)(ix)(A)

10. POWERLEVEL Ej 20.2203(a)(2)(ii) LI 50.36(c)(1)(ii)(A) LI 50.73(a)(2)(iv)(A) D 50.73(a)(2)(x)

LI 20.2203(a)(2)(iii) LI 50.36(c)(2) LI 50.73(a)(2)(v)(A) LI 73.71 (a)(4) 100% 10 20.2203(a)(2)(iv) LI 50.46(a)(3)(ii) LI 50.73(a)(2)(v)(B) LI 73.71(a)(5)

El 20.2203(a)(2)(v) LI 50.73(a)(2)(i)(A) Z 50.73(a)(2)(v)(C) LI OTHER I 20.2203(a)(2)(vi) LI 50.73(a)(2)(i)(B) Lii 50.73(a)(2)(v)(D) Specify inAbstract below or in

_________________ ______________________NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (include Area Code)

Laura B. Swenzinski, Senior Licensing Engineer /(319) 851-7724

13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT CA MANU- REPORTABLE E SYSTEM COMPONENT MANU- REPORTABLE USE SYSTEM COMPONENT FACTURER TO EPIX CAUS FACTURER TO EPIX X JM IEL. Alarm Lock N N/A N/A N/A N/A N/A

14. SUPPLEMENTAL REPORT EXPECTED 15.SEXPECTED MONTH DAY YEAR SUBMISSION LIYES (If yes, complete 15. EXPECTED SUBMISSION DATE) NO DATE ]

ABSTRACT (Limit to. 1400 spaces, i.e., approximately 15 single-spacedtypewritten lines)

On April 16, 2015, while operating at 100% power, workers opened doors concurrently when entering a secondary containment access airlock. The individuals involved each closed their respective doors upon encountering this unexpected condition; however, the result was a brief inoperability of secondary containment integrity. This resulted in an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event. The Resident Inspector was notified, and an Event Notification was made pursuant to 10 CFR 50.72(b)(3)(v)(C) due to a condition at the time of discovery that prevented the fulfillment of the Secondary Containment safety function (Reference EN#50989).

Following the event, the doors were verified to be functioning properly via Surveillance Test Procedure. A Root Cause Evaluation was conducted and determined the root cause of this event is that the airlock door interlock is not designed to prevent more than one airlock door from opening under all possible conditions.

This event did not result in a safety system functional failure. There were no radiological releases associated with this event.

NRC FORM 366 (02-2014)

NRC FORM 366A 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 lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information e-mail to Affairs, and Regulatory NEOB-10202, (3150-0104), Office of Management and Budget, CONTINUATION SHEET Washington, DC 20503. Ifa 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.

1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGE

- I SEQUENTIAL REV YEAR NUMBER NO.

Duane Arnold Energy Center 05000-331 2 OF 3 2015 003 - 01 NARRATIVE I. Description of Event:

On April 16, 2015 at 1320, while operating at 100% power, the Control Room Supervisor (CRS) was notified that Door 225 and Door 227, both in Secondary Containment Airlock 216 had been opened concurrently. The doors being open at the same time caused a failure to meet SR 3.6.4.1.2 to verify that either the outer door(s) or the inner door(s) in each Secondary Containment access opening are closed. The identified condition caused Secondary Containment to be considered inoperable per TS LCO 3.6.4.1. The-individuals involved immediately closed their respective doors upon encountering this unexpected

• condition. This action allowed SR 3.6.4.1.2 to be met, and restored Secondary Containment to an operable status.

This resulted in an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event. The Resident Inspector was notified, and an Event Notification was made pursuant to 10 CFR 50.72(b)(3)(v)(C) due to a condition at the time of discovery that prevented the fulfillment of the Secondary Containment safety function (Reference EN#50989). Secondary containment leak tightness is required to ensure that the release of radioactive materials from the primary containment is restricted to those leakage paths and associated leakage rates assumed in the accident analysis and that fission products entrapped within the secondary containment structure will be treated by the Standby Gas Treatment System prior to discharge to the environment.

The Secondary Containment airlock utilizes an interlock device with an adjustable permanent magnet (mounted on the door), and an electromagnet (on the door frame) arranged in an electrical circuit so that door(s) are held closed and/or areallowed to open. Immediately following the event, on April 16, 2015 at 1535 hours0.0178 days <br />0.426 hours <br />0.00254 weeks <br />5.840675e-4 months <br />, surveillance testing was performed satisfactorily per Surveillance Test Procedure (STP) 3.6.4.1-02, Secondary Containment Airlock Verification.

There were no radiological releases associated with this event. There were no other structures, systems or components inoperable at the start of this event that contributed to the event.

II. Assessment of Safety Consequences:

There were no actual safety consequences associated with this event; the potential safety consequences were minimal. Both doors on the airlock were open simultaneously for less than 10 seconds, and were able to close immediately upon discovery of the condition.

This event will not be reported as a safety system functional failure since an engineering analysis (Corrective Action ACE1968923-01) determined that the system is capable of performing its safety function during events when the airlock is open for less than 10 seconds. The post-LOCA dose calculation does not credit secondary containment integrity for mitigation of on-site and off-site doses for the first 5 minutes of the event. Therefore, this event is bounded by the existing dose calculation.

NRC FORM 366A (02-2014)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (02-2014) LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGE IYEAR Y SEQUENTIAL NUMBER REV NO.

Duane Arnold Energy Center 05000-331 3 OF 3 2015 - 003 - 01 NARRATIVE This event did not result in a safety system functional failure. There were no automatically or manually initiated safety system responses.

I1l. Cause of Event:

Technical Specifications Surveillance Requirement SR 3.6.4.1.2 requires one inner or one outer secondary containment airlock door to be closed at all times. A Root Cause Evaluation was conducted and determined the root cause of this event is that the airlock door interlock is not designed to prevent more than one airlock door from opening under all possible conditions.

Specifically, the interlock may allow opening both doors in an airlock if both permissive buttons are depressed simultaneously.

IV. Corrective Actions:

An operational check of the Secondary Containment door interlocks is performed monthly via STP 3.6.4.1-02, Secondary Containment Airlock Verification. Additionally, signs have been installed at each airlock door instructing personnel who are accessing or leaving the airlock to wait 2 seconds after activating the interlock before opening the door. This corrective action introduces a time delay, which allows additional time for the interlock mechanism to actuate and prevent the other door from being opened. TSTF-551, "Revise Secondary Containment Surveillance Requirements" will be implemented once approved.

V. Additional Information:

Previous Similar Occurrences:

A review of DAEC Licensee Event Reports from the past 5 years identified four similar occurrences, reference LER 2013-006, LER 2014-002, LER 2014-003 and LER 2015-001.

A review of the corrective action program identified additional occurrences of airlock conditions causing momentary secondary containment inoperability - eight additional occurrences in the past two years, with six of those occurring in the last year.

EIIS System and Component Codes:

IEL Interlock Reporting Requirements:

This event is being reported as an 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, IOCFR50.73(a)(2)(v)(C).

NRC FORM 366A (02-2014)