05000346/LER-2006-001, Emergency Diesel Generator Engine Damaged Due to Improper Torquing of Lock Nut
| ML061440276 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/22/2006 |
| From: | Bezilla M FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NP-33-06-001-01 LER 06-001-00 | |
| Download: ML061440276 (10) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2) 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 |
| 3462006001R00 - NRC Website | |
text
FENOC 5501 North State Route 2 FirstEnergy Nuclear Operating Company Oak Harbor, Ohio 43449 Mark B. Bezilla 419-321-7676 Vice President - Nuclear Fax: 419-321-7582 Docket Number 50-346 NP-33-06-001-01 10 CFR 50.73 License Number NPF-3 May 22, 2006 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001 Ladies and Gentlemen:
Licensee Event Report 2006-001-01 Emergency Diesel Generator Engine Damaged Due to Improper Torquing of Lock Nut Davis-Besse Nuclear Power Station, Unit No. 1 Date of Occurrence - January 20. 2006 Enclosed is Revision 01 to Licensee Event Report (LER) 2006-001. This LER was submitted to provide written notification of the discovery that an Emergency Diesel Generator (EDG) was inoperable following maintenance, for a period of time longer than the seven days permitted by the Technical Specifications. The EDG was returned to service with an improperly torqued lash adjustment screw lock nut on engine cylinder 4, which was due to an inadequate level of verification of the torquing operation. The damage observed on the cylinder 4 valve bridge would have prevented the EDG from supplying power to its respective 4160 Volt Essential Bus for the seven days specified in the Safety Analysis Report. Because this condition existed for approximately 14.7 days, this event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the Technical Specifications. In accordance with the guidance of NUREG-1022, revision bars have been added to the right margin to denote changes from the previous submittal of LER 2006-001 dated March 21, 2006. This revision provides the results of the evaluation into the decision that led to the conclusion that none of the possible causes of the tapping noise identified as part of post-maintenance testing warranted immediate investigation. Commitments associated with this LER are listed in the Attachment.
Very truly yours, GMW Attachment Enclosure cc:
Regional Administrator, USNRC Region III DB-1 Project Manager, USNRC DB-1 NRC Senior Resident Inspector Utility Radiological Safety Board
Docket Number 50-346 License Number NPF-3 NP-33-06-001-01 Attachment Page 1 of 2 COMMITMENT LIST The following list identifies those actions committed to by the Davis-Besse Nuclear Power Station in this document. Any other actions discussed in the submittal represent intended or planned actions by Davis-Besse. They are described only as information and are not regulatory
commitments
Please notify the Manager - Regulatory Compliance (419-321-8585) at Davis-Besse of any questions regarding this document or associated regulatory commitments.
COMMITMENTS
DUE DATE
- 1. Revise procedure DB-MM-09320, "Emergency and Station Blackout Diesel Engine Maintenance," to:
- Incorporate concurrent verification signoffs for the step that requires torquing of the lash adjustment screw lock nuts and any other operation for which concurrent verification is appropriate.
- Add additional signoffs for steps that require a torquing operation to be performed.
- Reorganize the procedure and associated enclosures to accommodate field work sequencing.
- Separate the procedure into individual procedures for each preventive maintenance activity (2-year, 4-year, 6-year, and 12-year preventive maintenance activities).
- 2. Report the results of the evaluation into the decision that led to the conclusion that none of the possible causes of the tapping noise identified as part of post-maintenance testing warranted immediate investigation. Also include in this LER supplement any remedial or preventive corrective actions from this evaluation.
- 3. Review event with mechanical maintenance personnel on the lessons learned. This review will focus on the expectation of using the approved place keeping method when performing a procedure that is designated "Step-By-Step" level of use. In addition, this review will include the consequences related to this event to the station and personnel.
- 1. Prior to the next major EDG outage, which is currently scheduled for the week of August 28, 2006 (EDG 1).
- 2. Complete with submittal of Revision 01 of this LER.
- 3. June 30, 2006
Docket Number 50-346 License Number NPF-3 NP-33-06-001-01 Attachment Page 2 of 2
COMMITMENTS
DUE DATE
- 4. Training will be presented to improve worker understanding and performance in the area of problem solving techniques. The target audience for this training will be engineering personnel, maintenance supervisors and above, and operations supervisors and above, who are typically involved in these types of problem solving issues.
- 5. The latest revision to procedure NOP-ER-3001, "Problem Solving and Decision Making," which has been implemented at other FirstEnergy Nuclear Operating Company facilities, will be implemented at the DBNPS. The current revision of this procedure provides a simplified, yet structured troubleshooting technique that can be used for equipment deficiencies that do not rise to the level of requiring a formal problem solving team.
- 4. September 14, 2006
- 5. July 14, 2006
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31150-0104 EXPIRES 6/30/2007 (6-2004)
, the NRC may (See reverse for required number of not conduct or sponsor, and a person Is not required to respond to, the digits/characters for each block)
Information collection.
- 3. PAGE Davis-Besse Unit Number 1 05000346 1 OF 7
- 4. TITLE Emergency Diesel Generator Engine Damaged Due to Improper Torquing of Lock Nut
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
moN DAY YEAR 05000 01 20 2006 2006 001 01 22 2006 FACILITY NAME DOCKET NUMBER
~VVV I.VI
-'~
~05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
[] 20.2203(a)(3)(i)
[I 50.73(a)(2)(i)(C) a 50.73(a)(2)(vii) 1 5
20.2201(d)
E 20.2203(a)(3)(ii) a 50.73(a)(2)(ii)(a) a 50.73(a)(2)(viii)(A) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(il)(B)
El 50.73(a)(2)(viii)(B) 0] 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [3 20.2203(a)(2)(ii) 5 50.36(c)(1)(li)(A) a 50.73(a)(2)(iv)(A)
O 50.73(a)(2)(x)
E0 20.2203(a)(2)(;ii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A)
El 73.71 (a)(4) 100 5
20.2203(a)(2)(Iv) 5 50.46(a)(3)(ii) 5 50.73(a)(2)(v)(B)
E 73.71(a)(5) 5 20.2203(a)(2)(v) a 50.73(a)(2)(i)(A) a 50.73(a)(2)(v)(C)
El OTHER I]
0.7 (a) 2Xv (D)Specify in Abstract 0
20.2203(a)(2)(vi) 3 50.73(a)(2)(i)(B) b 50.73(a)(2(v)(D) below
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME lTELEPHONE NUMBER (Include Area Code)
Gerald M. Wolf, Staff Engineer, Regulatory Compliance l (419) 321-8001CAUSE SYSTEM COMPONENT FACTURER TEPIX II
CAUSE
SYSTEM COMPONENT ANURER REPORTABLE
~S S
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION 5 YES (If yes, complete EXPECTED SUBMISSION DATE).
0 NO DATE Atm-
- -l -
- - i -
- - nA
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- 1____
I Ab I KA%(; I t Umit to 14UU spaces, i.e., approxnmately I5 single-spacea twpewriluen lines)
On January 20, 2006, while preparing Emergency Diesel Generator (EDG) 2 for testing, an investigation was performed of a tapping noise heard following overhaul maintenance the prior week. When the top deck on the EDG engine was opened, damage was discovered to a cylinder valve bridge. The damage was determined to be due to an improperly torqued lash adjustment screw lock nut, which was caused by inadequate verification of the torquing. The observed damage would have prevented the EDG from operating for its duty time of one week as specified in the Safety Analysis Report. Because the EDG was inoperable from the start of the six year preventive maintenance overhaul on January 8, 2006, until repairs were completed on January 23, 2006, or more than the seven days permitted by the Technical Specifications, this event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the Technical Specifications. The diesel engine maintenance procedure will be revised to incorporate concurrent verification for the step that requires torquing of the lash adjustment screw lock nuts and add additional signoffs for steps that require a torquing operation to be performed. Because a structured problem solving technique was not used when the tapping sound was first heard, training in problem solving techniques will also be given to applicable personnel.
NRC F-UOM 366 (O-2064)
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CORRECTIVE ACTIONS
- 6. LER NUMBER SEQUENTIAL REVISION YEAR NUMBER I NUMBER 2006 001 01 Prm 366A)
On January 20, 2006, upon discovery of the damage to EDG 2 cylinder 4 left valve bridge, repairs to the engine were initiated. All other adjusting screw lock nuts were checked and found to be tightened to at least the required torque value. The other 19 cylinders were inspected and no damage was found.
EDG 2 was declared operable on January 23, 2006, at 0642 hours0.00743 days <br />0.178 hours <br />0.00106 weeks <br />2.44281e-4 months <br /> after completion of maintenance and testing activities.
Procedure DB-MM-09320, "Emergency and Station Blackout Diesel Engine Maintenance," will be revised to incorporate concurrent verification signoffs for the step that requires torquing of the lash adjustment screw lock nuts and any other operation for which concurrent verification is appropriate.
Additional signoffs will also be added to the procedure for steps that require a torquing operation to be performed, which will allow the individual performing the torquing to initial that the task was completed.
The procedure and associated enclosures will be reorganized to accommodate field work sequencing, and the procedure will be separated into Individual procedures for each preventive maintenance activity (2-year, 4-year, 6-year, and 12-year preventive maintenance activities). These procedure changes will be implemented prior to the next major EDG outage.
This event will be reviewed with mechanical maintenance personnel on the lessons learned. This review will focus on the expectation of using the approved place keeping method when performing a procedure that is designated "Step-By-Step" level of use. In addition, this review will include the consequences related to this event to the station and personnel.
Training will be presented to improve worker understanding and performance in the area of problem solving techniques. The target audience for this training will be engineering personnel, maintenance supervisors and above, and operations supervisors and above, who are typically involved in these types of problem solving issues.
The latest revision to procedure NOP-ER-3001, "Problem Solving and Decision Making," which has been implemented at other FirstEnergy Nuclear Operating Company facilities, will be implemented at the DBNPS. The current revision of this procedure, which was not previously implemented at the DBNPS due to the impending Fourteenth Refueling Outage, provides a simplified, yet structured troubleshooting technique that can be used for equipment deficiencies that do not rise to the level of requiring a formal problem solving team.
FAILURE DATA:
There have been no Licensee Event Reports submitted by FENOC for the DBNPS in the last three years reporting an event associated with inoperability of an Emergency Diesel Generator due to damaged engine components or a maintenance activity.
An event was documented on a Condition Report in 2003 where inadequate written Preventive Maintenance instructions led to improper torquing of the EDG 2 piston cooling oil pipe flange bolts for one cylinder. Contributing to this 2003 event was the lack of sufficient written detail regarding the torquing of these piston cooling oil pipe flange bolts in procedure DB-MM-09320, "Emergency and Station Blackout Diesel Engine Maintenance." Corrective Actions were completed to revise the procedure and Preventive Maintenance instructions for these piston cooling oil pipe flange bolts.
(If more space is required, use additional copies of NRC Form 366A)As described earlier, the cause of this January 2006 event was not a lack of adequate instructions or detail, but miscommunication, a lack of verifications, and the overall structure of the procedure. As a result, a review of a sample of similar mechanical maintenance procedures was performed, and the level of verification of torquing operations was determined to be adequate to prevent an event similar to the one described in this LER. Therefore, the corrective actions taken for the 2003 event, which were due to different causes, could not have been expected to prevent this occurrence. The past occurrences do not indicate a generic or broader scope issue at the DBNPS.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
I NP-33-06-001 -01 CRs 06-00154, 06-00583