05000331/LER-2015-005, Regarding Automatic Start of Both Emergency Diesel Generators Due to Lightning Strike
| ML15352A030 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 12/16/2015 |
| From: | Vehec T NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-15-0335 LER 15-005-00 | |
| Download: ML15352A030 (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) 10 CFR 50.73(a)(2)(vii)(A), Common Cause Inoperability 10 CFR 50.73(a)(2)(ix) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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 |
| 3312015005R00 - NRC Website | |
text
EN ERG December 16, 2015 NG-1 5-0335 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 #2015-005 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
,-*-wV.A. Vehec Vce 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 0MB: NO. 3150-0104 EXPIRES: 0113112017 (02-214)
'*"*'*%*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 />.
- .tL(*,
- ,.Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden esuimate to the FOIA, Privacy and Information Collections LIE SE VE/RE O T L R Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LIE SE V NTEIE.JXI(Eintemet e-mail to Infocollects.Resoarce@nrc.gov, and to the Desk Officer. Office of Information and (See Page 2 for required number of Regulatory Afairs, NEOB-10202, (3150-0104), Office of Management and Badget, Washington, DC dgt/hrcesfor each block) 20503. If a means used to impose an information collection does not display a currently valid 0MB digis/caracerscontrol number, the NRC may not conduct or sponsor, ends paprson in not required to respond to, the information collection.
- 13. PAGE Duane Arnold Energy Center05 0-3 1
F 3
- 4. TITLE Automatic Start of Both Emergency Diesel Generators Due to Lightning Strike
- 5. EVENT DATE
- 6. LER NUMBER f
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MOT A ER YEAR SEUMENILR EVO MONTH DAY YEAR N/AN/
10 20 2015 2015 -
005 -_001 12 16 2015 N/AN/
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[]
20.2201(b)
[]
20.2203(a)(3)(i)
[]
50.73(a)(2)(i)(C)
E] 50.73(a)(2)(vii)
-[
20.2201(d)
[] 20.2203(a)(3)(ii)
[] 50.73(a)(2)(ii)(A)
III 50.73(a)(2)(viii)(A) 20.2203(a)C2(1)
[I] 20.223(a)(4)i()
[Ii 50.73(a)(2)(tii)(B
[
50.73(a)(2)(vii)(A) 10 OWRLEE 20.2203(a)(2)(ii)
[] 50.36(c)(1)(ii)(A)
[] 50.73(a)(2)(iii()
D] 50.73(a)(2)(ix)(A 10DOE LVL
[
20.2203(a)(2)(iii)
[] 50.36(c)(1)ii()
[] 50.73(a)(2)(iv)(A) 73 5.713(a)(4)(x E] 20.2203(a)(2)(iii)
[
50.36(c)(2)i)
E] 50.73(a)(2)(v)(B)
E] 73.71 (a)(5) 10%
20.2203(a)(2)(v)
[] 50.73(a)(2)(i)(A)
[] 50.73(a)(2)(v)(C)
[] OTHER
[] 20.2203(a)(2)(vi)
[]
50.73(a)(2)(i)(B)
[]
50.73(a)(2)(v)(D) specifyin Abstract belowor in V.
Additional Information
Previous Similar Occurrences:
A review of DAEC Licensee Event Reports from the past 5 years identified one similar occurrence. Reference LER 2014-005, "Automatic Start of Standby Diesel Generators Due to Grid Disturbance".
EllS System and Component Codes:
EK - Emergency Onsite Power Supply System Reportinaq Requirements:
This event is being reported due to a valid system actuation, 10CFR50.73(a)(2)(iv)(A).
I,
Description of Event
On October 20, 2015 at 1800, while operating at 100% power, a voltage transient due to a lightning strike resulted in an automatic start of both of the site's Emergency Diesel Generators (EDGs) (lEE Code EK). Neither EDG loaded onto its respective essential bus.
The EDGs started as a result of a dip in essential bus voltage to 62% that did not fully recover for approximately 24 cycles. A review of the system design showed that since the EDGs started on an automatic start signal of essential bus voltage less than 65% for greater than 12 cycles, the EDGs operated as designed. The 'A' EDG was secured at 1930 on October 20, 2015. The 'B' EDG was secured at 1947 on October 20, 2015.
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
The automatic starting of the EDGs in response to a short-duration under voltage condition had no personnel or radiological safety significance. Since the EDGs were capable of fulfilling their safety function throughout this event, there was no nuclear safety significance.
This event 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 Event Notification 51484 was made pursuant to 10 CFR 50.72(b)(3)(iv)(A) due to a valid system actuation. 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
An Apparent Cause Evaluation was completed. The apparent cause of the starting of both EDGs was a storm-induced voltage dip (fault) that was not appropriately mitigated by the Transmission Operator's 900MHZ radio trip signal. A review of the system design showed that since the EDGs started on an automatic start signal of essential bus voltage less than 65% for greater than 12 cycles, the EDGs operated as designed.
IV.
Corrective Actions
The 'A' EDG was secured at 1930 on October 20, 2015. The 'B' EDG was secured at 1947 on October 20, 2015.
Actions have been initiated by the local balancing authority and the Transmission Operator to replace the 900MHZ radio path with fiber optic cable to prevent an electrical storm from blocking the signal path.
V.
Additional Information
Previous Similar Occurrences:
A review of DAEC Licensee Event Reports from the past 5 years identified one similar occurrence. Reference LER 2014-005, "Automatic Start of Standby Diesel Generators Due to Grid Disturbance".
EllS System and Component Codes:
EK - Emergency Onsite Power Supply System Reportinaq Requirements:
This event is being reported due to a valid system actuation, 10CFR50.73(a)(2)(iv)(A).