05000369/LER-2004-002, Regarding Main Steam Isolation Valve Inoperable
| ML050060091 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 12/29/2004 |
| From: | Gordon Peterson Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 04-002-00 | |
| Download: ML050060091 (8) | |
| 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 |
| 3692004002R00 - NRC Website | |
text
Jf Duke GARY R.
PETERSON L~Power.Vice President EOPSPowere McGuire Nuclear Station A Duke Energy Company Duke Power MGOI VP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078-9340 704 875 5333 704 875 4809 fax grpeters@duke-energy.com December 29, 2004 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555 Subject: McGuire Nuclear Station, Unit 1 Docket No. 50-369 Licensee Event Report 369/2004-02, Revision 0 Pursuant to 10 CFR 50.73, Sections (a)(1) and (d), attached is Licensee Event Report (LER) 369/2004-02, Revision 0.
On November 4, 2004, McGuire Nuclear Station identified past instances where a Unit 1 Main Steam Isolation Valve (MSIV),
ISM-3, was inoperable for a period longer than permitted by plant Technical Specifications.
These instances represented an operation prohibited by Technical Specifications and are reportable as per the requirements of 10 CFR 50.73 (a)(2)(i)(B).
In addition, there was a period when 1SM-3 and another MSIV, 1SM-1, were simultaneously inoperable.
Therefore, this event is also being reported as a condition which could have prevented fulfillment of a safety function in accordance with the requirements of 10CFR50.73(a)(2)(v)(D).
Probabilistic risk assessment has determined this event to be of no significance to the health and safety of the public.
There are no regulatory commitments contained in this LER.
G. R. Peterson Attachment www.dukepower.cornm
U. S. Nuclear Regulatory Commission December 29, 2004 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. J. Shea (Addressee Only)
NRC Project Manager (McGuire)
U. S. Nuclear Regulatory Commission Mail Stop 0-7 D11 Washington, DC 20555-0001 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
Unit Status:
At the start of the event, Unit 1 was in MODE 3 (Hot Standby)
Event Description
In 2002, during maintenance, 1SM-3 ("C" Steam Generator Main Steam Isolation Valve) was re-assembled incorrectly which rendered it incapable of closing to isolate a steam line break from the other Unit 1 Steam Generators when required.
In consequence, 1SM-3 was inoperable for periods in excess of Technical Specification requirements.
In addition, there was a period when 1SM-3 and ISM-1 ("D" Steam Generator Main Steam Isolation Valve) were simultaneously inoperable.
This constituted a safety system functional failure.
Probabilistic risk assessment has determined this event to be of no significance to the health and safety of the public.
Event Cause
1SM-3 was assembled incorrectly and accepted due to deficiencies in the procedure used to maintain, re-assemble, and test Main Steam Isolation Valves.
Corrective Action
An extent of condition review determined that the 1SM-3 failure mode was not transportable to any other Unit 1 and Unit 2 Main Steam Isolation Valves. The procedure used to maintain, re-assemble, and test Main Steam Isolation Valves has been placed on hold pending revision.
1SM-3 was repaired.
NRC FORM 366 (6-2004)
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CORRECTIVE ACTIONS
- 1) An extent of condition review was performed and determined that the failure modes of 1SM-3 were not transportable to the remaining three Unit 1 MSIVs or the four Unit 2 MSIVs.
- 2) The procedure containing the instructions for maintaining, re-assembling, and testing the MSIVs has been placed on hold pending revisions to ensure adequate assembly instructions and acceptance criteria are provided to prevent re-occurrence of a failure similar to that experienced on 1SM-3.
- 3) 1SM-3 was repaired to correct the deficiencies identified in November of 2004.
SAFETY ANALYSIS
A probabilistic risk assessment of this event determined that the increase in the estimated core damage frequency (CDF) or large early release frequency (LERF) was insignificant.
Therefore, the event described in this LER was not significant with respect to the health and safety of the public.
The safety significance of the event described in the LER are also being evaluated with respect to Pressurized Thermal Shock (PTS) and any resulting impact on the integrity of the Unit 1 reactor vessel.
The preliminary results indicate that there are no PTS related reactor vessel integrity concerns resulting from this event.
If further evaluation results in conclusions contrary to this, a revision to this LER will be submitted providing this information.
ADDITIONAL INFORMATION
A review of the McGuire corrective action database did not identify any previous occurrences of a similar event.
Applicable Energy Industry Identification (EIIS) system and component codes are enclosed within brackets.
McGuire unique system and component identifiers are contained within parentheses.