05000369/LER-2007-004, Regarding Procedure Deficiency Identified for Performing a Manual Backwash of Nuclear Service Water (Rn) Strainers Due to Reliance on Non-Safety Instrument Air
| ML072890088 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 10/05/2007 |
| From: | Gordon Peterson Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| M-07-04313 LER 07-004-00 | |
| Download: ML072890088 (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), Loss of Safety Function |
| 3692007004R00 - NRC Website | |
text
Duke GARY R.
PETERSON
- EPower, Vice President McGuire Nuclear Station A Duke Energy Company Duke Power MG01 VP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078-9340 704 875 5333 October 5, 2007 704 875 4809 fax grpeters@duke-energy. corn U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555
Subject:
McGuire Nuclear Station, Units 1 and 2 Docket Nos. 50-369, 50-370 Licensee Event Report 369/2007-04, Revision 0 Problem Investigation Process (PIP) M-07-04313 Pursuant to 10 CFR 50.73, Sections (a) (1) and (d), attached is Licensee Event Report (LER) 369/2007-04, Revision 0, concerning the inability to manually backwash nuclear service water strainers during accident conditions.
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.
There are no regulatory commitments contained in this letter.
G. R. Peterson Attachment www.dukepower.comr
U.S. Nuclear Regulatory Commission October 5, 2007 Page 2 of 2 cc:
W. D. Travers U. S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 J.F. Stang, Jr.
Senior Project Manager (McGuire)
U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 H4A Rockville, MD 20852-2738 J. B. Brady Senior Resident Inspector U. S. Nuclear Regulatory Commission McGuire Nuclear Site Beverly 0. Hall, Section Chief Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1645
Abstract
On August 6, 2007, the "A" Train of the Nuclear Service Water (RN)
System was declared inoperable due to deficient procedure guidance for manually backwashing RN strainers during Design Basis Accidents (DBA).
The Station Instrument Air (VI) System is non-safety-related and cannot be relied upon to manually backwash the RN strainers during or following design basis accidents.
At the time of discovery, both units 1 and 2 were in Mode 1 (power operation) and operating at approximately 100 percent power.
It was determined there were two periods during the past three years when macro-fouling impacted A Train RN operability.
The duration of macro-fouling in 2004 exceeded the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time allowed by Technical Specifications (TS) and is reported as a condition prohibited by plant TS.
In addition, scheduled surveillances performed during the 2004 macro-fouling period rendered "B" Train System, Structure, and Components (SSC) inoperable resulting in two trains being simultaneous inoperable and is reportable as an event or condition that could have prevented the fulfillment of a safety function.
The root cause of this event was historical modifications to the RN Strainers were completed without an adequate evaluation of the safety-related to non-safety-related system interactions.
Immediate actions were taken to restore the ability to manually backwash RN during accident conditions without VI and a root cause evaluation was completed.
NRC FORM 366 (6-2004)
(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)
Planned:
- The Scope of Modifications and/or License Amendments necessary to eliminate the OBDN condition and associated compensatory actions will be defined by March 1, 2008.
- Implementation of Modifications and/or License Amendments for both Units 1 and 2 will be completed by the end of the Unit 2 Fall 2009 refueling outage.
" IOCFR50.59 qualified personnel and appropriate site engineering personnel will be trained on applicable deficiencies identified in the root cause evaluation of this event/condition by December 1, 2007.
- Air operated valves that receive a safety signal with a requirement to be manually repositioned to mitigate a DBA will be reviewed to determine if the licensing/design bases is met by December 1, 2007.
SAFETY ANALYSIS
Duke Energy used a risk-informed approach to determine the risk significance of the procedure deficiency and conditions that existed which could have led to clogging of the Nuclear Service Water System inlet strainers.
The preliminary risk assessment determined that the Conditional Core Damage Probability (CCDP) associated with this condition is
> 1E-6 for both Units 1 and 2.
The Conditional Large Early Release Probability (CLERP) associated with this condition is
>IE-07 for both Units 1 and 2.
This LER will be revised if the final approved safety analysis indicates a different result than reported in this section.
ADDITIONAL INFORMATION
A recurring event determination was performed researching the McGuire corrective action database for the previous five years and it was concluded this was not a recurring event.
There were no releases of radioactive materials, radiation exposures, or personnel injuries associated with this event.