05000331/LER-2018-002, Both Doors in Secondary Containment Airlock Opened Concurrently
| ML18228A752 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 08/16/2018 |
| From: | Dean Curtland NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-18-0094 LER 2018-002-00 | |
| Download: ML18228A752 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v), Loss of Safety Function |
| 3312018002R00 - NRC Website | |
text
August 16, 2018 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 Report 2018-002 NEXTeraM EN ERGY~
DUANE ARNOLD NG-18-0094 10 CFR 50.73 Please find attached the subject report submitted in accordance with 10 CFR
- 50. 73. This letter makes no new commitments or changes to any existing
commitments
Dean Curtland Site Director, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC cc:
Administrator, Region Ill, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016)
-*~~,
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.
~~
E Send comments regarding burden estimate to the FOIA, Privacy and Information Collections
~.
"**.... ~'* LICENSEE EVENT REPORT (LER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See Page 2 for required number of digits/characters for each block)
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 (See NUREG-1022, R.3 for instruction and guidance for completing this form control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
htt12://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3i)
- 3. PAGE Duane Arnold Energy Center 05000-331 1 OF 4
- 4. TITLE Both Doors in Secondary Containment Airlock Opened Concurrently
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR N/A N/A FACILITY NAME DOCKET NUMBER 7
9 2018 2018 -
002 - 00 8
16 2018 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(il D 50.73(a)(2)(i)(C)
D 50. 73(a)(2)(vii) 1 D 20.2201 (d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50. 73(a)(2)(viii)(A)
D 20.2203(a)(1 )
D 20.2203(a)(4)
D 50.73(a)(2)(ii)(B)
D 50. 73(a)(2)(viii)(B)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
D 5o.73(a)(2)(iii)
D 50. 73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(iv)(A)
D 50. 73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
D 73. 71 (a)(5) 100%
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
!XI 50.73(a)(2)(v)(C)
D OTHER D 20.2203(a)(2)(vi)
D 50. 73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
Specify in Abstract below or in I.
Description of Event
On July 9, 2018, at 1334, while operating at 100% power, workers opened doors concurrently when entering a secondary containment access airlock. The doors being open at the same time caused a failure to meet Technical Specification (TS) Surveillance Requirement (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.
The failure to meet SR 3.6.4.1.2 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#53496).
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, on July 9, 2018 at 1342 hours0.0155 days <br />0.373 hours <br />0.00222 weeks <br />5.10631e-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.
NRG FORM 366 (06-2016)
I REV NO.
00 3
- 3. PAGE OF 4
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.
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 previously 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.
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 five similar occurrences, reference LER 2013-006, LER 2014-002, LER 2014-003, LER 2015-001, and 2016-001.
EllS System and Component Codes:
IEL - Interlock, Electrical
Reporting Requirements
This event is reportable pursuant to 10CFR50.73(a)(2)(v) as an Event or Condition that Could Have Prevented Fulfillment of a Safety Function. 3. PAGE OF 4