05000331/LER-2015-003, Regarding Both Doors in Secondary Containment Airlock Opened Concurrently
| ML15166A016 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 06/09/2015 |
| From: | Vehec T NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-15-0179 LER 15-003-00 | |
| Download: ML15166A016 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3312015003R00 - NRC Website | |
text
NEXTera ENERGYi DARNOL June 9,2015 NG-1 5-0179 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 Report #2015-003 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
T. A. Vehec Vice President, 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: 01/3112017 (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
. 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 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 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.
YEAR N/A N/A FACILITY NAME DOCKET NUMBER 04 16 2015 2015 -
003 00 06 09 2015 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
FI 20.2201(b)
LI 20.2203(a)(3)(i)
[]
50.73(a)(2)(i)(C)
LI 50.73(a)(2)(vii)
El 20.2201(d)
LI 20.2203(a)(3)(ii)
LI 50.73(a)(2)(ii)(A)
[1 50.73(a)(2)(viii)(A) 1] 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[]
20.2203(a)(2)(i) ii 50.36(c)(1)(i)(A)
[] 50.73(a)(2)(iii)
[] 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) 10 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)
LI 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
LI OTHER LII 20.2203(a)(2)(vi)
LI 50.73(a)(2)(i)(B)
I]
50.73(a)(2)(v)(D)
Specify in Abstract below or in [j__________________________
(2)(v)(D)
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 are allowed 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.
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
A Root Cause Evaluation is currently being conducted for the March 21, 2015 event detailed in LER 2015-001. The March 21, 2015 event involved Door 225 and Door 228, in the same Secondary Containment Airlock 216. When completed, Supplemental Report 2015-001-01 will be submitted detailing the cause(s) and corrective action(s) for both the March 21, 2015 and April 16, 2015 events.
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. As discussed above, a Root Cause Evaluation is currently being conducted and when completed, a Supplemental Report will be submitted detailing the cause(s) and corrective action(s) for this event.
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.
ElIS System and ComDonent 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).