05000255/LER-2007-006, Emergency Diesel Generator Inoperable in Excess of Technical Specification Requirements
| ML072500072 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 08/24/2007 |
| From: | Schwarz C Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 07-006-00 | |
| Download: ML072500072 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2552007006R00 - NRC Website | |
text
Enlergy Nuclear Operations, Inc.
Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Tel269 764 2000 August 24,2007 I 0 CFR 50.73(a)(2)(i)(B)
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Palisades Nuclear Plant Docket 50-255 License No. DPR-20 Licensee Event Report 07-006, Emer~ency Diesel Generator l noperable In Excess Of Technical Specification Requirements
Dear Sir or Madam:
Licensee Event Report (LER)07-006 is enclosed. The LER describes the inoperability of emergency diesel generator 1-2 for a period of time longer than allowed by Technical Specifications. The occurrence is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B).
Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
Site vice President Palisades Nuclear Plant Enclosure (1)
CC Administrator, Region Ill, USNRC Project Manager, Palisades, USNRC Resident Inspector, Palisades, USNRC
ENCLOSURE 1 LER 07-006, Emergency Diesel Generator [noperable In Excess Qf "I"eckvrical Specification Requirements 3 Pages Follow
incorporated Into the l~censlng process and fed back LICENSEE EVENT REPORT (LEW)
Nuclear Regulatory Comm~ss~on, Wash~ngton, DC 2055
~nfocollects@nrc gov, and to the Desk Off~cer, Off~ce (See reverse for required number of Irs, NEOB-10202, (3150-0066), Offlce of Management a d~gitslcharacters for each block)
If a means used to impose an ~nformat~on collect~on do mergency Diesel Generator Inoperable In Excess Of Technical Specification Requirements Spec~fy In Abstract below or In SUBMISSION days between October 28,2005, and November 20,2005, emergency diesel generator (EDG) 1-2 would have been unable to operate satisfactorily for the EDG1s required 30-day mission time, and therefore, was inoperable. This period corresponds to the time during which defective snubber valves on cylinders 5R and 5L were installed in EDG 1-2. While a failure of one snubber valve would not make EDG 1-2 inoperable, EDG 1-2 would not be able to meet design loading requirements with two failed snubber valves.
Consequently, EDG 1-2 was inoperable for a period of time longer than the 7 days allowed by Palisades Technical Specification (TS) 3.8.1.B.4. Additionally, during the period EDG 1-2 was inoperable, EDG 1-1 was made inoperable for approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the performance of its monthly surveillance. Therefore, both EDGs were simultaneously inoperable for a period of time longer than the 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> allowed by TS 3.8.1.E.1.
This event is reportable in accordance with 10 CFR 5OS73(a)(2)(i)(B) as a condition prohibited by Technical Specifications. U.S. NUCLEAR REGULATORY COMMISSION (1 -2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FAClLlTV NAME (1)
Palisades Nuclear Plant DOCKET NUMBER (2) r j
m 05000-255 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
EVENT DESCRIPTION
On February 22, 2007, during testing of emergency diesel generator (EDG) 1-2 [DG;EK], a fuel oil leak was identified from a cracked snubber valve in the fuel oil injection system at the discharge of the cylinder 5L fuel pump. The snubber valve functions to dampen pulsations created by the fuel injection system and also serves as the fuel oil pressure boundary. This occurrence was determined to be similar to a previous snubber valve leak that had been identified on cylinder 5R of EDG 1-2, on November 20, 2005. An evaluation determined that the failed 5R and 5L snubber valves had been installed in EDG 1-2 during the same maintenance activity in October 2005.
On July 25, 2007, a past operability evaluation was completed which concluded that during the 23 days between October 28,2005, and November 20,2005, EDG 1-2 would have been unable to operate satisfactorily for the EDG's required 30-day mission time, and therefore, was inoperable.
This period corresponds to the time during which defective snubber valves on cylinders 5R and 5L were installed in EDG 1-2. While a failure of one snubber valve would not make EDG 1-2 inoperable, EDG 1-2 would not be able to meet design loading requirements with two failed snubber valves.
Consequently, EDG 1-2 was inoperable for a period of time longer than the 7 days allowed by Palisades Technical Specification (TS) 3.8.1.B.4. Additionally, during the period EDG 1-2 was inoperable, EDG 1-1 was made inoperable for approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the performance of its monthly suweillance. Therefore, both EDGs were simultaneously inoperable for a period of time longer than the 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> allowed by TS 3.8.1.E.1.
This event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
CAUSE OF THE EVENT
The failure of snubber valves 5R and 5L was due to improper heat treatment of the material used in their construction, causing the snubber valves to crack during engine operation.
The 5R snubber valve failure occurred after approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of EDG operation since the 5R snubber valve was installed in the EDG. Following the 5R snubber valve failure and subsequent replacement, a 24-hour test run of the EDG was satisfactorily completed. Vendor input was obtained indicating that snubber valves failing from improper material heat treating would be expected to exhibit this condition within the initial 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation. Since all installed snubber valves (including snubber valve 5L and others installed in October 2005) had experienced more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of EDG run time with no indication of cracking, it was determined to be unnecessary to replace additional snubber valves at that time. Subsequently, the 5L snubber U.S. NUCLEAR REGULATORY COMMISSION I
LICENSEE EVENT REPORT QLER)
TEXT CONTINUATION valve exhibited its failure on February 22, 2007, after approximately 135 hours0.00156 days <br />0.0375 hours <br />2.232143e-4 weeks <br />5.13675e-5 months <br /> of run time since November 20,2005.
FACILIW NAME (1)
Palisades Nuclear Plant Palisades' experience with snubber valve cracking from improper heat treating of the snubber valve material is associated with snubber valves constructed from AlSl ES52100 alloy only.
DOCKET NUMBER (2) 05000-255
CORRECTIVE ACTIONS
TEXT (If more space is required, use add~tional copies of NRC Form 366A) (17)
Snubber valve 5L and the remaining snubber valves on EDG 1-2 that were originally installed in October 2005 have been replaced.
All snubber valves for EDG 1-1 have been replaced with snubber valves verified to be other than AlSl ES52100 alloy.
All stock snubber valves have been verified to be an alloy other than AlSI ES52100. Additionally, snubber valves constructed from this alloy will no longer be procured.
SAFETY SIGNIFICANCE
The event is considered to be of very low safety significance.
When considering the 30-day mission time for the EDG, if the limiting postulated scenario requiring the EDG safety function had occurred, EDG 1-2 would have been able to acceptably carry loads for the initial 135 hours0.00156 days <br />0.0375 hours <br />2.232143e-4 weeks <br />5.13675e-5 months <br /> (approximately 5.5 days) from the onset of the occurrence until the failure of the second snubber valve (5L). This extended period provides ample time for implementing other recoverylmitigating strategies, including restoration of offsite power, restoration of the opposite train EDG (EDG 1 -I), or repair of EDG 1-2.
PREVIOUS SIMILAR EVENTS
Licensee Event Report 05-007, Inoperable Emergency Diesel Generator For A Time Longer Than Permitted By Technical Specifications, dated January 19, 2006 Cancellation of Licensee Event Report 05-007, dated July 7, 2006