ML12334A481
| ML12334A481 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/12/2011 |
| From: | Kiley M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| SECY RAS | |
| References | |
| RAS 21523, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 | |
| Download: ML12334A481 (5) | |
Text
United States Nuclear Regulatory Commission Official Hearing Exhibit Entergy Nuclear Operations, Inc.
In the Matter of:
(Indian Point Nuclear Generating Units 2 and 3) v....~f\ REGU<..q" ASLBP #: 07-858-03-LR-BD01 NYS000031
- ~~~'
Docket #: 05000247 l 05000286
< 0 Exhibit #: NYS000031-00-BD01 Identified: 10/15/2012 Submitted: December 12, 2011
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c;- Admitted: 10/15/2012 Withdrawn:
'e-/i-o? ~O~ Rejected: Stricken:
- Other:
- F=PL.
POWERING TODAY, EMPOWERING TOMORROW,-
NOV 19 2010 10 CFR § 50.73 L-2010-272 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re: Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2010-003-00 Date of Event: September 23,2010 Reactor Trip Due to Fault on 230kV Side of Generator Step-Up Transformer The attached Licensee Event Report 05000250/2010-003-00 is being submitted pursuant to 10 CFR 50.73(a)(2)(iv)(A) due to a valid actuation of the Reactor Protection System resulting in a reactor trip.
If there are any questions, please call Mr. Robert Tomonto at 305-246-7327.
Very truly yours, Michael Kiley Vice President Turkey Point Nuclear Plant Attachment cc: Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant an FPL Group company OAGI0001050_00001
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 10-2010)
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 FOIAIPrivacy Section (T-5 F53), U.S. Nuclear LICENSEE EVENT REPORT (LER) Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.resourse@nrc.gov, and to the Desk Officer, Office 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 r.
control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME
, 2. DOCKET NUMBER PAGE Turkey Point Unit 3 050000250 1 OF 4
- 4. TITLE Reactor Trip Due to Fault on 230kV Side of Generator Step-Up Transformer
- 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR ISEQUENTIAL NUMBER I REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 09 23 2010 2010 - 003 - 00 11 19 2010
- 9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check al/ that apply)
D 20.2201(b) D 20.2203(a)(3)(i) 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 50.73(a)(2)(iii) D 50.73(a)(2)(ix)(A)
- 10. POWERLEVEL D 20.2203(a)(2)(ii) D 50.36(c)(1 )(ii)(A) I2l 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) 100%
D 20.2203(a)(2)(iv) D 50.46(a)(3)(ii) D 50.73(a)(2)(v)(B) D 73.71 (a)(5)
D 20.2203(a)(2)(v) D 50.73(a)(2)(i)(A) D 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 NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER NAME ITELEPHONE NUMBER (Include Area Code)
Ronald Everett 305-246-6190
- 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT MANU- REPORTABLE MANU- REPORTABLE CA.USE SYSTEM COMPONENT CAUSE SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX VA TEe X EL XFMR YES ELIN
- 14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEAR SUBMISSION D YES (If yes, complete 15. EXPECTED SUBMISSION DA TE) I2l NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 23, 2010, with Unit 3 operating at 100% power, an unplanned automatic reactor trip occurred at approximately 17:14:40 when an electrical flashover on the high side of the Unit 3 Generator Step Up (GSU) transformer occurred. All systems responded as designed At 17:52, a notification (EN# 46274) was made to the NRC Operations Center in accordance with 10 CFR 50.72(b)(2)(iv)(B) due to actuation of the Reactor Protection System with the reactor critical and 10 CFR 50.72(b)(3)(iv)(A) due to Auxiliary Feedwater System actuation. The Unit 3 reactor and turbine tripped due to a generator differential protection relay trip. This event was entered into the Corrective Action Program as AR 582206. All systems functioned as normal with the exception of Control Rod G5 in Control Bank A which indicated 18 steps. The unit entered and exited E-O "Reactor Trip" and ES-0.1 "Reactor Trip Response." All 4kV buseshad power from the Unit 3 StartUp Transformer. Heavy weather (rain and wind) conditions existed at the time of the reactor trip. The root cause was an external flashover to ground of the "C" phase high voltage (HV) bushing. The Unit 3 GSU Transformer High Voltage Bushings (all phases) were replaced with longer bushings. Transformer Surge Arresters, Stand Off Insulators, Conductors, and Generator Radial Lead Seals were replaced.
NCR FORM 366 (10-2010)
OAG10001050_00002
NRC FORM 366A u.s. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEEr
- 1. FACILITY NAME 2. UUlOl\1:. 6. LER NIIMRFR 3. PAGE YEAR I SEQUENTIAL NUMBER IREVISION NUMBER Turkey Point Unit 3 05000250 Page 2 of 4 2010 - 003 -., 00 NARRATIVE DESCRIPTION OF THE EVENT On September 23,2010, with Unit 3 operating at 100% power, an unplanned automatic reactor trip occurred at approximately 17:14:40 when an electrical flashover on the high side of the Unit 3 Generator Step Up Transformer [EL, XFMR] occurred. All systems responded as designed At 17:52, a notification (EN# 46274) was made to the NRC Operations Center in accordance with 10 CFR 50.72(b)(2)(iv)(B) due to actuation of the Reactor Protection System with the reactor critical and 10 CFR 50.72(b)(3)(iv)(~) due to Auxiliary Feedwater System actuation. Unit 3 reactor [AB,RCT] and turbine
[TA,TRB] tripped due to a generator differential protection relay trip. This event was entered into the Corrective Action Program as AR 582206. All systems functioned as normal with the exception of Control Rod G5 in Control Bank A which indicated 18 steps. The unit entered and exited E-O "Reactor Trip" and ES-O.l "Reactor Trip Response." All 4kV buses had power from the Unit 3 Start Up Transformer. Heavy weather (rain and wind) conditions existed at the time of the reactor trip.
CAUSE OF THE EVENT The event was evaluated to determine the root cause and contributing causal factors. The root cause was an external flashover to ground of the "c" phase high voltage (HV) bushing. The root cause did not originate with the GSU transformer or connected 230kV transmission system. The one cause that could not be refuted was the potential for rapid contamination of the GSU transformer bushing due to steam/canal water carryover effluent from the circulating water system condenser water box priming system. If this was the cause, the priming system deficiencies that could have contributed to the rapid contamination event include a clogged moisture separator drain line loop seal, failed condenser water box check valves, and a corroded silencer of the circulating water condenser water box primary system ejector that no longer performed moisture separation and did not prevent saline laden steam and water droplets from exiting the system. Nonetheless, evidence supporting this potential cause was not found.
ANAL YSIS OF THE EVENT At the time of the event, it was raining. However, no lightning was recorded at the plant at the time of the event based on the National Lightning Detection Network and eyewitness accounts. Wind speed was approximately 9 miles per hour with wind gusts. Interviews revealed that a heavy rain continued after the event. Consequently, any contamination evidence was likely removed.
REPORTABILITY The event is reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) due to automatic actuation of the Reactor Protection System when an unplanned reactor trip occurred and 10 CFR 50.73(a)(2)(iv)(B) due to automatic actuation of the Auxiliary Feedwater System.
NRC FORM 366A (10-2010)
OAG10001050_00003
NRC FORM 366A u.s. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEEr
- 1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGE YEAR I SEQUENTIAL NUMBER I REVISION NUMBER Turkey Point Uni~ 3 05000250 Page 3 of 4 2010 - 003 - 00 NARRATIVE ANAL YSIS OF SAFETY SIGNIFICANCE The plant responded as expected to the automatic reaCtor trip. Although one control rod indication remained at 18 steps, the control rod was subsequently verified to be fully inserted and the rod position indicator was appropriately adjusted.
CORRECTIVE ACTIONS Immediate Corrective Actions:
- Replace GSU Transformer Surge Arresters (all phases)
- Replace 230kV Stand OffInsulators (all phases)
- Internal inspection of the GSU transformer
- Generator Radial Lead Seals were replaced Corrective Actions to Prevent Recurrence:
- 1. Implement long term action plan for the Unit 3 and 4 Circulating Water System to mitigate degradation issues that lead to canal water carryover. Action plan to improve the following:
o Silencer condition and performance o Moisture separator (3/4T34) drain line operation o Water box vacuum tank check valves operation o Vacuum air leaks.
(Complete)
Contributing Cause Corrective Actions:
- 1. Unclogged moisture separator drain loop seal. (Complete)
- 2. Replaced the silencer of the Circulating Water Condenser Water Box Priming System Ejector.
(Complete)
- 3. Replaced all four condenser water box vacuum tank check valves (Complete)
NRC FORM 366A (10-2010)
OAG10001050_00004
NRC FORM 366A u.s. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEEr
- 1. FACILITY NAME 2. UU~"1:: 6. LER NUMBER J. PAGE YEAR I I SEQUENTIAL REVISION NUMBER NUMBER Turkey Point Unit 3 05000250 Page 4 of 4 2010 - 003 - 00 NARRATIVE ADDITIONAL INFORMATION EllS Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].
FAILED COMPONENTS IDENTIFIED: Unit 3 Step-Up transformer PREVIOUS SIMILAR EVENTS: None NRC FORM 366A (10-2010)
OAG10001050_00005