05000370/LER-2010-002, Regarding Nuclear Service Water System a Train Past Inoperable Due to Failed Strainer Differential Pressure Instrument
| ML103630400 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 12/20/2010 |
| From: | Repko R Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 10-002-00 | |
| Download: ML103630400 (9) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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 |
| LER closed by | |
| IR 05000369/2011004 (28 October 2011) | |
| 3702010002R00 - NRC Website | |
text
Duke REGIS T. REPKO Vice President Energyý McGuire Nuclear Station Duke Energy MG01VP /-12700 Hagers Ferry Rd.
Huntersville, NC 28078 980-875-4111 980-875-4809 fax regis. repko@duke-energy. com 10 CFR 50.73 December 20, 2010 U.S. Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, D.C. 20555
Subject:
Duke Energy Carolinas, LLC McGuire Nuclear Station, Unit 2 Docket Nos. 50-370 Licensee Event Report (LER) 370/2010-02, Revision 0 Problem Investigation Process (PIP) M-10-05982 Pursuant to 10 CFR 50.73 Sections (a) (1) and (d), attached is Licensee Event Report 370/2010-02, Revision 0, regarding the past inoperability of the Unit 2 "A" Train Nuclear Service Water System.
This report is being submitted in accordance with 10 CFR 50.73 (a) (2) (i) (B), an Operation Prohibited by Technical Specifications, and 10 CFR 50.73 (a) (2) (v) (B), any Event or Condition That Could Have Prevented Fulfillment of the Safety Function needed to remove residual heat. The LER is not complete, and will be supplemented upon completion of the root cause analysis.
At this time, this event is considered to be of no significance with respect to the health and safety of the public.
There are no regulatory commitments contained in this report other than the commitment to submit a supplement to the LER. Duke Energy expects to supply that supplement within 60 days, but does not consider that time frame to be a commitment.
If questions arise regarding this LER, contact Rick Abbott at 980-875-4685.
Very truly yours, Regis T. Repko Attachment www. duke-energy. com
U.S. Nuclear Regulatory Commission December 20, 2010 Page 2 cc:
L. A. Reyes Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 J. H. Thompson Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852-2738 J. B. Brady NRC Senior Resident Inspector McGuire Nuclear Station W. L. Cox III, Section Chief North Carolina Department of Environment and Natural Resources, Division of Environmental Health Radiation Protection Section
- - 1645 Mail Service Center Raleigh, NC 27699-1645
Abstract
On October 22,
- 2010, it was determined air in-leakage past a threaded fitting on the low pressure side of the Differential Pressure (DP)loop affected the past operability of the Unit 2 "A" (2A!)
Train of Nuclear Service Water System (NSWS).
A fitting was disconnected and reconnected during,,preventive maintenance performed July 24, 2010 which resulted in air in-leakage through the low pressure side of the DP loop and caused an error in the differential pressure indication at high flow conditions when the strainer operates at a vacuum.
Action was taken to repair the fitting and restore 2A NSWS Train to operable. Actions are identified in the site's Problem Identification Process to revise the retest (post maintenance testing) necessary to validate operability of the RN strainer DP instruments at vacuum conditions.
This LER will be supplemented when the root cause evaluation is finalized.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) instrumentation loops after restoring disconnected field process tubing or after a suspected field process tubing leak.
- 3. Review the effect of this vacuum condition with respect to the effects on issues such as post maintenance/modification testing on other components in the RN suction path which could be vulnerable to the vacuum condition.
SAFETY ANALYSIS
Engineering analysis was used to make a quantitative assessment of the safety significance for the 2A [BI]
(RN)
DP indication failure. Using a conservative strainer clogging probability, a Conditional Core Damage Probability (CCDP) was calculated considering the duration of the LCO non-compliance and was determined to be less than 1E-06. This would be considered to be of no significance to the health and safety of the public.
ADDITIONAL INFORMATION
This section will be updated as part of the supplement to the LER.
Nuclear Energy Institute (NEI) 99-02, "Regulatory Assessment Performance Indicator Guideline", defines a Safety System Function Failure identical to 10 CFR 50.73(a)
(2)
(v) criteria.
Consequently, reporting an event as an event or condition that could have prevented the fulfillment of the safety function of structures, systems and components constitutes a Safety System Function Failure for the same basis used to deem the reporting criteria was met. This event is being reported under 10 CFR 50.73(a) (2) (v) because the Unit 2 "B" [BI]
(RN)
Train was declared inoperable for short durations to perform work activities within the period of time that the 2A Train [BI]
(RN) was inoperable.
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