05000366/LER-2017-002, Regarding Emergency Diesel Generator Start Due to Inadvertent Electrical Bus De-Energization
| ML17103A412 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/13/2017 |
| From: | Vineyard D Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-17-0624 LER 17-002-00 | |
| Download: ML17103A412 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| LER closed by | |
| IR 05000321/2017002 (3 August 2017) | |
| 3662017002R00 - NRC Website | |
text
David R. Vineyard Hatch Nuclear Plant
& Southern Nuclear Vice President - Plant Hatch 11028 Hatch Parkway North Baxley, GA 31513 April13, 2017 Docket No.:
50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 2 LEA 2017-002-00 912 537 5859 tel 912 366 2077 lax NL-17-0624 Emergency Diesel Generator Start Due to Inadvertent Electrical Bus De-Enerqization Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company (SNC) hereby submits the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please contact Greg Johnson at (912} 537-5874.
Respectfully submitted, David R. Vineyard Vice President-Hatch DRV/jcb Enclosure: LEA 2017-002-00
U. S. Nuclear Regulatory Commission NL-17-0624 Page2 cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. R. D. Gayheart, Fleet Operations General Manager Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch RTYPE: CHA02.004 U.S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. R. Hall, NRR Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch
Edwin I. Hatch Nuclear Plant Unit 2 LER 2017-002-00 Emergency Diesel Generator Start Due to Inadvertent Electrical Bus De-Energization
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 />.
LICENSEE EVENT REPORT (LER)
Reported lessons learned are incorporated into the licensing process and fed back to industry.
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Send comments regarding burden estimate to the FOIA, Privacy and Information Collections (See Page 2 for reql.ired number of digits/characters for each block)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory (See NUREG-1 022, R.3 for instruction and guidance for completing this form 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 control htto://www.nrc.gov/reading-rm/doc-collection§lnur§Qs/staff/sr1 022/@
number, the NRC may not conduct or sponsor, and a person is not required to respond to, the inlnrmotinn onlloo~M
.PAGE Edwin I. Hatch Nuclear Plant Unit 2 05000366 1 OF3
- 4. TITLE Emergency Diesel Generator Start Due to Inadvertent Electrical Bus De-Energization
- 5. EVENT DATE
- 6. LEA 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 FACILITY NAME DOCKET NUMBER 02 16 2017 2017
- - 002
- - 00 4
13 2017
- 9. OPERAllNG 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)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 5 D 20.2201 (d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A) 18150.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5) 0 D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1)
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50.73(a)(2)(i)(C) 00THER Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LEA ICENSEE CONTACT
~~LEPHONE NUMBER {Include Area Code)
Edwin I. Hatch I Jimmy Collins - Licensing Supervisor 912-537-2342
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
I8J NO SUBMISSION DATE ABSTRACT (Umit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On February 16, 2017, at 1320 EST with Unit 2 at 0 percent rated thermal power due to being in a refueling outage, maintenance electricians were sent to the field to perform a protective relay trip test for the 2D start-up transformer (SAT). During the test setup, the 2E 4160 VAC Emergency Bus was inadvertently and momentarily de-energized, causing the 2A Emergency Diesel Generator (EDG) to autostart, secondary containment to isolate, and start of the standby gas treatment system. Subsequent investigations revealed that the cause of the event was due to a movement operated contact (MOC) switch adapter was not required to be installed on the 2D normal supply breaker in the 2E 4160 VAC bus. All systems responded appropriately.
A review of the event determined that the MOC switch adapter was not required to be installed by the procedure, but was instructed to be installed by supervision. Corrective actions were taken to cover supervisor roles and responsibilities and the need for all workers to follow plant standards for procedure use and adherence. All breaker procedures and protective relay test procedures were reviewed to determine if a MOC switch adapter needs to be installed. Continuing training will also be held to cover this event and its lessons learned.
NRC FORM 366 (06-2016)
Event Description
On February 16, 2017, at 1320 EST with Unit 2 at 0 percent rated thermal power due to being in a refueling outage, maintenance electricians were sent to the field to perform a protective relay trip test for the 2D start-up transformer (SAT) (EllS Code XMFR). During the test setup, the 2E 4160 VAC Emergency Bus (EllS Code BU) was inadvertently and momentarily de-energized, causing the 2A Emergency Diesel Generator (EDG) (EllS Code DG) to autostart, secondary containment to isolate, and start of the standby gas treatment system. Although, the 2A EDG autostarted, it did not tie to the 2E 4160 VAC Emergency Bus as the 2E 4160 VAC Emergency Bus was re-energized from the 2C SAT.
Subsequent investigations revealed that a movement operated contact (MOC) switch adapter had been installed on the 2D normal supply breaker in the 2E 4160 VAC Emergency Bus. The procedure did not call for the MOC switch adapter to be installed and was installed at the direction of supervision. The switch adapter caused the alternate supply breaker that was feeding the 2E 4160 VAC Emergency Bus to momentarily open and then reclose, consequently ending the event.
Event Cause Analysis
The cause of the event is due to a MOC switch adapter being incorrectly installed on the 2D normal supply breaker in the 2E 4160 VAC Emergency Bus. Causal analysis determined that the MOC switch adapter was not required to be installed per the procedure. The supervisor made the decision to install the adapter after a review of the electrical prints and assumed he had eliminated the trip potential by opening the appropriate link. The supervisor stepped out of role and did not follow plant standards for procedure use and adherence.
Safety Assessment
This event is reportable per 10 CFR 50.73(a)(2)(iv)(A) due to the valid actuation of an emergency ac electrical power system that was not part of a pre-planned sequence.
The electrically powered safety loads are separated into redundant load groups such that loss of any one group will not prevent the minimum safety functions from being performed. Essential loads are divided between the three essential 4160 VAC Emergency Buses: 2E, 2F, and 2G. Availability of any two of these buses is sufficient to meet any accident conditions. The startup transformers are used to supply the 4160 VAC buses during normal operation, maintenance outages, and shutdown. Emergency buses 2E, 2F, and 2G are normally supplied by the 2D startup transformer. On failure of the normal source (2D transformer), the three emergency buses are energized from the 2C startup transformer. This is accomplished by an automatic transfer. In the event that both startup transformer supplies are lost, the power supply for the emergency buses is fed from emergency diesel generators.
Upon a momentary loss of the 2E Emergency Bus supply power, the alternate supply power breaker automatically reclosed, reenergizing the bus. All respective systems operated as designed upon the momentary loss of power and no component failures were identified. Due to Unit 2 being in a scheduled refueling outage, shutdown cooling was being provided by the Decay Heat Removal (DHA) system during this time. Therefore, there was no loss of shutdown cooling and the outage safety assessment was not impacted by this event. This event is considered to have very low
safety significance
Page 2 of 3 (06-2016)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 rC,.,.
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LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collectionslnureaslstaff/sr1022/@
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 e-mail to lnlocollects.Resource@nrc.gov, and to the Desk Officer, Olfice of Information and 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 control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER Edwin I. Hatch Nuclear Plant Unit 2 05000-366 YEAR I
SEQUENTIAL I REV NUMBER NO.
2017
- - 002
Corrective Actions
A stand down was held with all maintenance supervisors to cover supervisor roles and responsibilities and the need for all workers to follow plant standards for procedure use and adherence. Also, a stand down was held with craft personnel to reinforce the need to always follow the procedure and to not deviate from written procedures even under the direction of supervision. All breaker procedures and protective relay test procedures were reviewed to determine if a MOC Switch Adapter needs to be installed. Continuing training will also be held to cover this event and its lessons learned.
Previous Similar Events
None.
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