05000364/LER-2007-001, Unit 2 Reactor Trip During Unit 1 Main Generator Differential Lockout Relay Testing
| ML073250090 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 11/19/2007 |
| From: | Jerrica Johnson Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-07-2176 LER 07-001-00 | |
| Download: ML073250090 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat |
| 3642007001R00 - NRC Website | |
text
Vice President - Farley J.R.Johnson Southern Nuclear Vice President - Farley Operating Company, Inc, Post Office Drawer 470 Ashford, A,iabama 36312-047D Tet 334814.451 i Fax 334.814.4l28 SOUTHERN A COMPANY November 19, 2007 Docket No.:
50-364 NL-07-2176 U. S. Nuclear Regulatory Commission ATrN: Document Control Desk Washing1on, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2007-001-00 Unit 2 Reactor Trip during Unit 1 Main Generator Differential Lockout Relay Testing Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company (SNC) is submitting the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely,
~.'!
JRJ/MML Enclosure: Unit 2 Licensee Event Report 2007-001-00
U. S. Nuclear Regulatory Commission NL-07-2176 Page 2 cc: Southern Nuclear Ooerating Company Mr. J. T. Gasser, Executive Vice President Mr. J. R. Johnson, Vice President - Farley Mr. D. H. Jones, Vice President - Engineering RTYPE: CFA04.054; LC # 14682 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Ms. K. R. Cotton, NRR Project Manager - Farley Mr. E. L. Crowe, Senior Resident Inspector - Farley
Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2007-001-00 Unit 2 Reactor Trip during Unit 1 Main Generator Differential Lockout Relay Testing Enclosure Unit 2 Licensee Event Report 2007-001-00
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMS: NO. 3150-0104 EXPIRES: 0813112007 (9-2007)
Estimated burden per response to comply with this mandatory collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incO/POrated into the licensing process and fed back to industry. Send commenlS r~di~ burden LICENSEE EVENT REPORT (LER) estimate to the Records and FOIAIPrivacy SSNice Branch ( -5 F 2), U.S.
Nuclear R~uIatory Commission, Washington, DC 20555-0001, or ~ internet e*mail to in ocolIectsOnrc~. and to the Desk Officer, OffICe of In ormation and Regulatory Affairs, NE B-10202, (3150-0104). Office of Management and Budget, Washington. DC 20503. II a means used to impose an information collection does not display a currenUy valid OMS control number, the NRC may not conduct Of sponsor, and a person is not required to respond to. the information collection.
- 13. PAGE Joseph M. Farley Nuclear Plant Unit 2 05000364 1 OF 3
- 4. TITLE Unit 2 Reactor Trip during Unit 1 Main Generator Differential Lockout Relay Testing
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILmES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 10 03 2007 2007
- 001 - 00 11 19 2007 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201 (b) o 2O.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 5O.73(a)(2)(vii) 1 o 20.2201 (d) o 2O.2203(a)(S)(ii) o 50.73(a)(2)(ii)(A) o 5O.73(a)(2)(viij)(A) o 20.2203(a)(1) o 2O.2203(a)(4) o 50.73(a)(2)(ii)(B)
[] 5O.73(a)(2)(viji)(B) o 20.2203(a)(2)(i) o 5O.36(c)(1 )(i)(A) o 5O.73(a)(2)(iii)
[J SO.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(0)(1 )(ii)(A) 181 50.73(a)(2)(iv)(A) o SO.73(a)(2)(x) o 2O.2203(a)(2)(iii) o 5O.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71(a)(4) 100 o 2O.2203(a)(2)(iv) o 5O.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71(a)(5) o 2O.2203(a)(2)(v) o 5O.73(a)(2)(i)(A) o 5O.73(a)(2)(v)(C) o OTHER o 2O.2203(a)(2)(vi) o 5O.73(a)(2)(i)(B) o 50,73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME ITELEPHONE NUMBER (Include Area Code)
~. A. Johnson - Vice President 334-899-5156 CAUSE SYSTEM COMPONENT MANU REPORTABLE
CAUSE
SYSTEM COMPONENT MANU REPORTABLE FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION o YES (If yes, complete 15. EXPECTED SUBMISSION DA TE) 18100 DATE IABSTRACT (Limit to 1400 spaces, i.e., apprOXimately 15 single-spaced typewritten lines)
On October 3, 2007 at 1410, with the reactor at 100% power, Unit 2 automatically tripped due to a loss of power to the Unit 2 B-train electrical distribution system [EA]. This occurred during a Unit 1 refueling outage while performing testing on Unit 1 Main Generator Differential Lockout relay. As a result, the supply breaker to 2B Startup Transformer was inadvertently tripped. The loss of Unit 2 B-train 4160V power Ultimately led to a loss of power to Reactor Coolant Pump (RCP) Breaker Indication (1 out of 3 coincidence). The reactor tripped per design. All safety systems functioned as designed.
This event was caused by a testing procedure that lacked a step to block the High Voltage Switchyard (HVSY) breaker failure sequence relays. The failure to block resulted in the breaker failure sequence relays actuating. The breaker failure sequence relays tripped the associated HVSY breakers, which then de-energized the 2B Startup Transformer. Loss of the 28 Startup Transformer ultimately led to loss of RCP Breaker Indication relay. resulting in Unit 2 reactor trip.
The subject procedure has been revised.
NRC FOAM 366 (9-2007)
PRINTED ON RECYCLED PAPER (If more space is required, use additionalcopies of NRC Form 366A) (17)
Plant and System Identification
Westinghouse*- Pressurized Water Reactor Energy Industry Identification Codes are identified in the text as [XX]
Description of Event
On OCtober 3,2007 at 1410, with the reactor at 100% power. Unit 2 automatically tripped due to a loss of power to the Unit 2 B*train electrical distribution system lEA]. This occurred during a Unit 1 refuellng outage while performing testing on Unit 1 Main Generator Differential Lockout relay. Upon manual actuation of an HEA relay for testing of the Unit 1 Main Generator Differential Lockout Relay, all breakers to the #1
- 230 KV bus and the Webb offsite power line unexpectedly tripped, including breaker 944, which was supplying the 2B Startup Transformer. As a result, the supply breaker to 2B Startup Transformer was inadvertently tripped.
Loss of power from the 2B Startup Transformer ultimately de-energized the Reactor Coolant Pump (RCP) breaker position indication relay.
Cause of Event
This event was caused by a testing procedure that lacked a step to block the High Voltage SWitchyard (HVSY) breaker failure sequence relays. The failure to block resulted in the breaker failure sequence relays actuating.
The breaker failure sequence relays tripped the associated HVSY breakers, which then de-energized the 2B Startup Transformer. Loss of the 28 Startup Transformer ultimately led to loss of RCP Breaker Indication relay (1 out of 3 coincidence). resulting in Unit 2 reactor trip. The de-energization of the 28 Startup Transformer was caused by a loss of feed associated from the HVSY breaker failure sequence relay actuation and an Auto Bank transformer being removed from service for maintenance.
Safety Assessment
All safety systems functioned as designed after the trip. Loss of power to Emergency Safeguards Features (ESF}
busses was restored automatically by the Emergency Alternating Current (EAC) power system Diesel Generator set. Both main feedwater pumps tripped follOWing the reactor trip. In each case, the trip was attributed to a slow automatic startup of a redundant support pump following loss of electrical power. The main feedwater pumps remained recoverable from the control room using established procedures, if they had been needed. Therefore, the health and safety of the public were unaffected by this event.
This event does not represent a Safety System Functional Failure.
This event represents an Unplanned Scram. According to data reporting guidelines, this event did not represent an Unplanned Scram with Complications since power to ESF busses was restored automatically and main feedwater pumps were recoverable.
NRC FORIA 366A (9-2007 u.s. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
(9-2007)
CONTINUATION SHEET
- 2. DOCKET
- 6. LER NUMBER I
- 3. PAGE SEQUENTIAL IREVISION
- 1. FACIUTY NAME YEAR NUMBER NUMBER Joseph M. Farley Nuclear Plant Unit - 2 05000 364 3
OF 3
2007 001 00 NARRAnVE (If more space is required, use additional copies ofNRC Form 366A) (17)
Corrective Action
The sUbject testing procedure has been revised. In addition, similar procedures were reviewed and revised dUring U1 RF21.
The Maintenance procedure writer's guide has been revised to include requirements to obtain utility transmission personnel's concurrence with technical content for procedures that include circuits that interface with the HVSY.
Prior to use, remaining relay test procedures will be revised in accordance with Maintenance procedure writer's guidance.
Additional Information
Other systems affected: No systems other than those already mentioned in this report were affected by this event.
Commitment information: This report does not create any permanent licensing commitments.
Previous similar events
There have been no similar LEA's in the past two years.
PRINTED ON RECYCLED PAPER NRC FOAM 3II6A (9-2007