05000458/LER-2005-003, Re Operation Prohibited by Technical Specifications Due to Diesel Generator Malfunction
| ML053180172 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 11/04/2005 |
| From: | Lorfing D Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBF1-05-0186, RBG-46491 LER 05-003-00 | |
| Download: ML053180172 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4582005003R00 - NRC Website | |
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- - Entergy Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 Tel 225 381 4157 Fax 225 635 5068 dlorfin~entergy.com David N. Lorfing Manager-licensing November 4, 2005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47 Licensee Event Report 50-458 / 05-003-00 File Nos.
G9.5, G9.25.1.3 RBG-46491 RBF1 0186 Ladies and Gentlemen:
In accordance with 10CFR50.73, enclosed is the subject Licensee Event Report.
This document contains no commitments.
Sincerely, David N. Lorfing Manager - Licensin!
DNL/dhw Enclosure
- - J,(---
Licensee Event Report 50-458 / 05-003-00 November 4, 2005 RBG-46491 RBF1-05-0186 Page 2 of 2 cc:
U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 NRC Sr. Resident Inspector P. O. Box 1050 St. Francisville, LA 70775 INPO Records Center E-Mail Mr. Jim Calloway Public Utility Commission of Texas 1701 N. Congress Ave.
Austin, TX 78711-3326 Mr. Ronnie Wascom Louisiana Department of Environmental Quality Office of Environmental Compliance P.O. Box 4312 Baton Rouge, LA 70821-4312
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/3012007 (6-2004)
, the NRC may digits/characters for each block) nnot conductor sponsor. and a person is not required to respond to, the
- 3. PAGE River Bend Station, Unit 1 05000 458 1 of 4
- 4. TITLE Operation Prohibited by Technical Specifications Due to Diesel Generator Malfunction
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED S
AFACILITY NAME DOCKET NuMBER MONTH DAY YEAR YEAR NUMENTIA R ENV MONTH DAY YEAR 05000 O
FACILITY NAME DOCKET NUMBER 09 09 2005 2005 - 003 -
00 11 04 2005 05000
- 9. OPERATING MODE 11.THISREPORTISSUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
O 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 0
20.2201(d)
D 20.2203(a)(3)(ii) a 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
El 20.2203(a)(1) a 20.2203(a)(4) a 50.73(a)(2)(ii)(B) a 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i) a 50.36(c)(1)(i)(A)
E 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0 20.2203(a)(2)(ii) a 50.36(c)(1)(ii)(A) a 50.73(a)(2)(iv)(A)
[I 50.73(a)(2)(x) o 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71 (a)(4)
El 20.2203(a)(2)(iv)
E 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (include Area Code)
David N. Lorfing, Manager-Licensing 225-381-4157CAUSE SYSTEM CO MPO NENT MANU REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE SYTM CMOET FACTURER TO EPIX FACTURER TO EPIX A
EK DG TDI jClPlEN
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 9, 2005, with the plant operating at 100 percent power, the results of an ongoing investigation concluded that the Division 1 emergency diesel generator had been inoperable for approximately 23 days during July 2005. This was due to a cracked tube in the engine jacket water cooling system that may have prevented the generator from fulfilling its safety function. River Bend Technical Specifications allow a maximum outage time of 14 days for the emergency diesel generator. This condition is being reported in accordance with 10CFR50.73(a)(2)(i)(b) as operations prohibited by Technical Specifications. The tubing was replaced on July 31, 2005, thus the condition no longer existed at the time of discovery.
NRC FORM 366 (6-2054)
PRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
FAILURE CONTINUATION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I
NUMBER NUMBER River Bend Station Unit 1 05000-458 2005 003 00 2
OF 4
REPORTED CONDITION On July 8, 2005, a scheduled 24-hour test of the Division 1 diesel generator (DG) (**DG**) was nearing completion when a minor leak was identified at a compression fitting (**TBG**) in the jacket water cooling system. The leak was originally quantified at approximately one drop per second. A mechanic performed a tightness check on the fitting, but the leakage rate did not change. On July 31, 2005, the Division 1 DG was run in preparation for a planned maintenance inspection. The DG had been operating for approximately 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> when the jacket water tubing separated at the same fitting, causing a significant leak. The DG was quickly shut down in a controlled manner, and no high temperature condition occurred. The tubing was then disassembled and repaired using a new fitting.
On September 9, 2005, the results of the evaluation of the failed tubing fitting concluded that the as-found condition of the tubing on July 8 may have caused it to separate before the DG could complete its safety function under postulated accident conditions. Thus, the DG was inoperable for the period of July 8 - 31, or approximately 23 days. This exceeds the 14 day allowable outage time for the DG in River Bend Technical Specifications.
This event is being reported in accordance with 10CFR50.73(a)(2)(i)(b) as operations prohibited by Technical Specifications.
INVESTIGATION The failed tubing was in the jacket water return path from the oil cooler on the engine governor. This section of half-inch diameter stainless steel tubing was installed with a compression fitting. The break occurred inside the nut and compression ferrule. This section of tubing had been fabricated on site at the time the DG was originally installed in approximately 1984.
This investigation determined that there was a pre-existing crack around approximately half the tubing circumference at the site of the failure. An examination of the crack determined that it had likely existed before the discovery of the minor leak on July 8. While it could not be determined how long the tubing had been cracked, no leakage had been observed prior to July 8. The final break of the tubing was a tension failure that allowed it to separate and come out of the compression fitting. The most probable cause of the failure was a combination of normal engine vibration and damage caused by over-tightening during past maintenance.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
FAILURE CONTINUATION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE ISEQUENTIAL REVISION YEAR NUMBER NUMBER River Bend Station Unit 1 05000-458 2005 003 00 3
OF 4
Maintenance practices regarding repair of minor leaks on the DG had, in the past, allowed for simple tightening of the affected fitting. The investigation of this event has concluded that this practice likely led to over-tightening of the ferrule nut at some time prior to the discovery of the minor leak on July
- 8. The decision not to disassemble and repair the fitting on July 8 was based on inaccurate judgment on the part of the system engineer and the mechanic. It was concluded that this leak would behave like past minor leaks of this type, where a fitting continued to leak for an indefinite time, but retained integrity until corrected. It was not suspected that the tubing was cracked, or that it had a short remaining service life.
CORRECTIVE ACTIONS
In 2003, a condition involving reassembly of oil piping on a reactor feed pump resulted in training for the mechanical maintenance staff on correction of leaks in compression fittings. This training is pertinent to the reported event, in that the tightness check that was performed on July 8 was in accordance with current maintenance guidelines. As described above, an examination of the failed tubing indicated that the circumferential crack had existed before discovery of the minor leak on July 8, and likely resulted from a combination of normal engine vibration and damage caused by over-tightening during past maintenance (prior to the 2003 maintenance training). Thus, no further corrective action is deemed necessary in this area.
An analysis of the causal factors for this event is being used to communicate lessons learned in the Engineering and Maintenance departments. This action is being tracked in the station's corrective action program.
PREVIOUS OCCURRENCE EVALUATION A review of prior reported leaks on the Division 1 and 2 DGs found that a damaged compression fitting was discovered and repaired in 2003. The investigation of that condition determined that the damage was caused during the maintenance period immediately preceding the discovery, due most likely to external contact with the tubing. This did not appear to be a case of progressive damage caused by over-tightening the fitting. Thus, thisU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
FAILURE CONTINUATION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION River Bend Station Unit 1 05000-458 2005 003 00 4
OF 4
condition did not present an opportunity to prevent the failure of the jacket water tubing on July 31.
SAFETY SIGNIFICANCE
During the period that the Division 1 DG was inoperable, the Division 2 DG remained in service (except for planned maintenance) to perform the safety function to provide a safety-related source of onsite emergency power. On three occasions, the Division 2 DG was removed from service briefly for scheduled surveillance tests. The duration of these three periods totaled 69 minutes. In each case, the DG was under the direct control of an operator implementing approved procedural guidance. Thus this event was of minimal safety significance.
(NOTE: Energy Industry Component Identification codes are annotated as (**XX**).)
NRC FURM 366B (1-2001)