05000269/LER-2010-001, For Oconee, Unit 1, Regarding Standby Shutdown Facility Letdown Line Orifice Strainer Blocked by Valve Gasket Material
| ML101160034 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/21/2010 |
| From: | Baxter D Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| O-09-7536 LER 10-001-00 | |
| Download: ML101160034 (13) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) |
| 2692010001R00 - NRC Website | |
text
Duke DAVE BAXTER SEnergy Vice President Oconee Nuclear Station Duke Energy ON01 VP / 7800 Rochester Highway Seneca, SC 29672 864-873-4460 864-873-4208 fax dabaxter@dukeenergy.com April 21, 2010 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555
Subject:
Oconee Nuclear Station
,Docket Nos. 50-269, -270, -287 Licensee Event Report 269/2010-01, Revision 0 Problem Investigation Process No. 0-09-7536 Gentlemen:
Pursuant to 10 CFR 50.73 Sections (a)(1) and (d), attached is Licensee Event Report 269/2010-01, Revision 0, regarding inoperability of the Standby Shutdown Facility (SSF)
Reactor Coolant Make-Up (RCMU) system letdown flow path, specifically on Oconee Unit 1, due to foreign material clogging a strainer. Units 2 and 3 were affected to a lesser degree, and the effect on those units is still under evaluation.
This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(b) as operation prohibited by Technical Specifications and in accordance with 10 CFR 21.21 as a reportable defect. The report is not complete, and will be supplemented upon completion of additional testing and evaluation necessary to support the root cause and determination of safety impact of this event. 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. Duke Energy expects to supply that supplement within 60 days, but does not consider that time frame to be a commitment.
Any questions regarding the content of this report should be directed to Randy Todd at 864-873-3418.
Sincerely, fDave Baxter, Vice President Oconee Nuclear Site Attachment A-f www. duke-energy. com
Document Control Desk Date: April 21, 2010 Page 2 cc:
Mr. Luis Reyes 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 Washington, D.C. 20555 Mr. Andrew Sabisch NRC Senior Resident Inspector Oconee Nuclear Station INPO (Word File via E-mail)
Abstract
On 10/11/2009, while Unit 1 was in Mode 5, the Standby Shutdown Facility (SSF) Reactor Coolant Make-Up (RCMU) system letdown flow path failed a flow test. Subsequently, troubleshooting inspections found foreign material (FM), i.e., Grafoil FM from a Flowserve Model 1878 valve backseat gasket and "legacy" FM (particles of epoxy, austenitic stainless steel shavings, and a paint chip), upstream of an orifice strainer (strainer). The strainer and backseat gasket were removed. Based on inspection of similar valves, vendor assurance of no recorded similar gasket failures, and prior flow tests, the equivalent lines on Unit 2 and 3 were considered Operable.
On 2/18/2010 at 2250, while operating at 100% in Mode 1, Unit 2 SSF RCMU was declared inoperable due to recognition that the strainer could be partially blocked and might collapse during an event. Power was reduced to access the strainer. FM, including Grafoil, was found; the strainer was removed. On 2/23/2010, Unit 3 power was reduced to access the strainer.
FM, including Grafoil, was found; the strainer was removed.
The root cause of this event is an inadequately selected strainer. Inadequate testing and FM from the backseat gasket contributed. The backseat gasket failure is reported as a Part 21 defect. The significance of this event is under review and pending further testing/analyses. A supplement will be submitted.
NRC FORM 366 (7-2001)
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(currently scheduled to start 4/25/2010 and 10/23/2010 respectively). The completion schedule for the other corrective actions has not been finalized.
(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component that has been, is being, or will be given to purchasers or licensees.
As stated above, Duke Energy has provided information on this event to the industry via Nuclear Network. In addition, this LER, and planned supplement, will be submitted to the NRC. No other advice or notification is planned at this time.
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