05000269/LER-2011-002, For Oconee Nuclear Station, Regarding Completion of a Shutdown Required by Technical Specifications for an Inoperable Containment Isolation Valve
| ML110690973 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/09/2011 |
| From: | Gillespie T Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 11-002-00 | |
| Download: ML110690973 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown |
| 2692011002R00 - NRC Website | |
text
Duke T.
PRESTON GILLESPIE, Jr.
Dukeg Vice President
- Energy.
Oconee Nuclear Station Duke Energy ONO0 VP / 7800 Rochester Hwy.
Seneca, SC 29672 864-873-4478 864-873-4208 fax T. Gillespie@duke-energy. com March 9, 2011 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555
Subject:
Oconee Nuclear Station Docket No. 50-269 Licensee Event Report 269/2011-02, Revision 0 Problem Investigation Program No.: 0-11-0218 Gentlemen:
Pursuant to 10 CFR 50.73 Sections (a)(1) and (d), attached is Licensee Event Report 269/2011-02, Revision 0, regarding Oconee Unit 1 completing a shutdown required by Technical Specification (TS) on January 8, 2011.
This report is being submitted in accordance with 10 CFR 50.73 (a)(2)(i)(A). There are no regulatory commitments contained in this report. This event is considered to be of no significance with respect to the health and safety of the public. Cause analysis for this event is not yet complete. The root cause evaluation results and corrective actions associated with the inoperable containment isolation valve will be provided in a supplement to this report.
Any questions regarding the content of this report should be directed to Bob Meixell, Oconee Regulatory Compliance Group, at 864-873-3279.
Sincerely T
T. Preston Gillespie, J Vice President Oconee Nuclear Station Attachment www. duke-energy comr
Document Control Desk March 9, 2011 Page 2 cc:
Mr. Victor McCree Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Mr. John Stang Project Manager U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Mail Stop 8 G9A Washington, D.C. 20555 Mr. Andrew Sabisch NRC Senior Resident Inspector Oconee Nuclear Station INPO (Word File via E-mail)
Abstract
On January 8, 2011, during performance of Engineered Safeguards (ES) logic testing for Unit 1 ES digital channel 2, the wiring jumper intended to prevent travel of letdown line containment isolation valve 1HP-5 became dislodged and the signal to close the valve became active. Upon investigation of the unintended valve closure 1 HP-5 was found to be approximately 25 percent open. When the jumper was reinstalled, 1 HP-5 returned to the fully open position. However, because the valve did not fully close, it was declared inoperable.
Technical Specification (TS) Limiting Condition for Operation 3.6.3 entry conditions were met at 0148 hours0.00171 days <br />0.0411 hours <br />2.44709e-4 weeks <br />5.6314e-5 months <br /> on January 8, 2011, for an inoperable containment isolation valve. Unit 1 initiated a shutdown at 1401 hours0.0162 days <br />0.389 hours <br />0.00232 weeks <br />5.330805e-4 months <br /> on January 8, 2011 (NRC Event Notification 46526), completed the shutdown required by TS when Unit 1 entered Mode 3 at 1731 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.586455e-4 months <br /> on January 8, 2011, and exited the TS mode of applicability when Unit 1 entered Mode 5 at 1419 hours0.0164 days <br />0.394 hours <br />0.00235 weeks <br />5.399295e-4 months <br /> on January 9, 2011.
An investigation identified galling between the gland ring and valve body of 1 HP-5. Corrective actions included replacement of the valve gland ring with one made from material that is less susceptible to galling and increasing the clearance between the gland ring and valve body. The immediate cause that resulted in the valve not fully closing has been addressed. However, the root cause evaluation is not yet complete. The final results of the root cause evaluation and any additional corrective actions will be provided in a supplement to this report. This event is considered to have no significance with respect to the health and safety of the public.
NRC FORM 366 (10-2010)
EVALUATION:
BACKGROUND 1HP-5 is a containment isolation valve [ISV] in the Oconee Unit 1 Letdown System [CB]. 1HP-5 is normally open during unit power operation to allow letdown flow from the Reactor Coolant System [AB]. The valve serves as the outside containment isolation valve on penetration number 6 and is automatically closed by an Engineered Safeguards (ES)[JE] signal. ES channel 2 automatically de-energizes a solenoid valve to close 1 HP-5. 1 HP-5 also receives a close signal on high letdown temperature to terminate letdown flow; however this function is provided to prevent damage to the Purification Demineralizers [CB] (equipment protection) rather than for nuclear safety.
The failure of 1 HP-5 to fully close on January 8, 2011, resulted in an inoperable condition of 1 HP-5.
The appropriate Technical Specification (TS) was entered and a shutdown of Oconee Unit 1 was completed.
The NRC was notified of the initiation of the shutdown required by TS 3.6.3 in accordance with 10 CFR 50.72(b)(2), (NRC Event Notification 46526).
The completion of the Unit 1 shutdown is reportable per 10 CFR 50.73 (a)(2)(i)(A).
Prior to this event Unit 1 was operating at 100 percent power with no safety systems or components out of service that would have contributed to this event.
EVENT DESCRIPTION
On January 8, 2011, during performance of ES logic testing for Unit 1 ES digital channel 2, the wiring jumper intended to prevent travel of letdown line containment isolation valve 1 HP-5 became dislodged and the signal to close the valve became active. Upon investigation of the unintended valve closure 1 HP-5 was found to be approximately 25 percent open. When the jumper was reinstalled, 1 HP-5 returned to the fully open position. However, because the valve did not fully close, it was declared inoperable.
TS Limiting Condition for Operation (LCO) 3.6.3 entry conditions were met at 0148 hours0.00171 days <br />0.0411 hours <br />2.44709e-4 weeks <br />5.6314e-5 months <br /> on January 8, 2011, for an inoperable containment isolation valve. Unit 1 initiated a shutdown at 1401 hours0.0162 days <br />0.389 hours <br />0.00232 weeks <br />5.330805e-4 months <br /> on January 8, 2011 (NRC Event Notification 46526), completed the shutdown required by TS when Unit 1 entered Mode 3 at 1731 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.586455e-4 months <br /> on January 8, 2011, and exited the TS mode of applicability when Unit 1 entered Mode 5 at 1419 hours0.0164 days <br />0.394 hours <br />0.00235 weeks <br />5.399295e-4 months <br /> on January 9, 2011.
The immediate cause that resulted in the valve not fully closing has been addressed, the valve was restored, post maintenance testing was completed, and the valve was returned to service.
However, the root cause evaluation is not yet complete. The final results of the root cause evaluation and any additional corrective actions will be provided in a supplement to this report.
This event is considered to have no significance with respect to the health and safety of the public.
CAUSAL FACTORS The apparent cause was determined to be valve material galling that resulted in the valve not fully closing. This has been addressed and the valve was returned to service. However, the root cause evaluation is not yet complete. The final results of the root cause evaluation and any additional corrective actions will be provided in a supplement to this report.
CORRECTIVE ACTIONS
Immediate:
TS LCO 3.6.3 was entered. Actions were taken in accordance with TS LCO 3.6.3 including Oconee Unit 1 shutdown.
Subsequent:
- 1. 1 HP-5 gland ring material was replaced with a material less susceptible to galling, and the clearance between the gland ring and valve body was increased.
- 2. 1 HP-5 was restored, post maintenance testing performed, and 1 HP-5 was returned to service.
Planned:
Cause analysis for this event is not yet complete. The root cause evaluation results and corrective actions associated with the inoperable containment isolation valve will be provided in a supplement to this report.
There are no NRC Commitment items contained in this LER.
SAFETY ANALYSIS
The TS shutdown of Unit 1 was uncomplicated with no significant equipment issues other than 1HP-5 inoperability. Unit 1 shutdown was completed within TS 3.6.3 LCO required completion times. Therefore there was no impact on the health and safety of the public due to this event.
Additional safety analysis information will be provided in the supplement to this report.
ADDITIONAL INFORMATION
There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.
This event is considered reportable under the Equipment Performance and Information Exchange (EPIX) program.