IR 05000289/1989009

Insp Rept 50-289/89-09 on 890213-16.Potential Violation Noted.Major Areas Inspected:Diesel Generator Air Sys Failures

ML20235Y727
Person / Time
Site:	Three Mile Island
Issue date:	02/28/1989
From:	Bennett W, Constable G, Greg Pick NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20235Y718	List: ML20235Y715 ML20235Y727
References
50-298-89-09, 50-298-89-9, NUDOCS 8903140529
Download: ML20235Y727 (5)

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' APPENDIX'

U.S.' NUCLEAR REGULATORY COMMISSION

REGION IV

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NRC Inspection Report: 50-298/89-09 Operating' License: DPR-46 Docket: 50-298 Licensee: Nebraska Public Power District (NPPD) .:

'P.O. Box 499  ;

Columbus, Nebraska 68602-0499 i

' Facility Name: Cooper Nuclear Station (CNS)

Inspection At: CNS, Nemaha County, Nebraska l

Inspection-Conducted: February 13-16, 1989 j Inspectors: M A JM9 G. A. Pick, Resident Inspector, Project Section C, Date Division of Reactor Projects  !

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W. R. Bennett, Senior Resident Inspector, Project Date  !

Section C, Division of Reactor Projects .j

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Approved: ,

GrL? Constable, Chief, Project Section C, Division 2Mffy Date of Reactor Projects C

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1 -Inspection Summary Inspection Conducted February 13-16, 1989 (Report 50-298/89-09)

Areas Inspected: Special, unannounced inspection of diesel generator (DG) ai ~ system failure Results: On February 13, 1989, a fitting on the control air system to DG No. I failed'during the monthly DG operability surveillance. The failure

. was due to personnel error and inadequate corrective actions following previous similar failures, which allowed installation of an incorrect fittin One potential violation (failure to maintain diesel generator operable) was identified. An enforcement conference to discuss this potential violation will be held in the Region IV offic _ - _ _ _ _ _ _ _ - _ - _ _ _ _ _ _ _ _

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' Persons Contacted Principal Licensee Employees

• G. R. Horn, Division Manager of Nuclear Operations

• V. L. Wolstenholm, Division Manager of Quality Assurance

• J. M. Meacham, Senior Manager, Technical Support

• E. M. Mace, Engineering Manager

• R. Brungardt, Operations Manager

• D. M. Norvell, Maintenance Manager

• K. C. Walden, Licensing Manager

• L. E. Bray, Regulatory Compliance Specialist J. R. Flaherty, Engineering Supervisor

• G. A. Schmielau, Instrument and Control Foreman

• G. E. Smith, Quality Assurance Manager D. Dageforde, Systems Engineer

• Denotes those present during the exit interview conducted on February 16, 198 The NRC inspectors also interviewed other licensee employees during the inspection perio . Followup of Plant Events (93702)

13, 1989, the monthly operability test of Diesel On February (DG) No. I was being performed. Approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> into the Generator surveillance, licensee personnel manually shut down DG No. I after observing control air system pressure decreasing, as indicated on a local pressure gauge. After shutdown, the DG was declared inoperabl The licensee determined that air pressure was decreasing due to a cracked fitting connecting a control air pressure gauge to the overspeed trip mechanism. This fitting had previously failed on January 17, 1989. If

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the DG had not been manually shut down, the cracked fitting would have eventually allowed 30 psi control air to bleed off from the overspeed trip valve. The loss of control air to the overspeeo trip mechanism would then secure 80 psi air to the fuel racks. The fuel racks would have closed, shutting off fuel flow to the cylinders, thereby stopping the engin After the DG failure on January 17, part of the licensee's corrective u

action was to replace the cracked fitting. During the repair activity, I

the licensee determined that no exact replacement nipple for the fitting was available on site. The cognizant engineer determined that a thin-walled nipple was satisfactory as a replacement for the failed nipple. This determination was made without performing the required Equipment Specification Change for form, fit, and function. The thin-walled nipple did not meet vibration resistance requirements and subsequently l

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I failed after the diesel had been operated for less than 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. The replacement part did not allow DG No. I to perform its intended function, therefore, DG No. I was inoperable from the time of its initial failure (January 17,1989). Technical Specification (TS) 3.5.F.1 allows reactor operation for only seven days with one DG inoperable. Operating from January 17 to February 13, 1989, with one DG inoperable was identified by the NRC inspectors as a potential violatio In response to the February 13, 1989, failure, the licensee reduced reactor power and replaced the failed fitting with a required thick-walled fittin In addition, Maintenance Work Requests (MWR) 89-0853 and 89-0868 were approved which replaced a large portion of control air, fuel oil, and lube oil tubing. The MWRs also installed stainless steel flexible tubing on the overspeed safety shutdown valve to reduce vibration between the j

diesel engine and off-engine components. The NRC inspectors observed that the modifications were properly reviewed and approved by the Station Operations Review Committee on February 13 and February 15, 1989. The modifications were performed in accordance with the MWRs and approved maintenance procedures. Postmaintenance testing was specified in the MWR and properly performed and documente During the maintenance activities on the DGs, TS required surveillance were properly performed and Limiting Conditions for Operations were correctly followed. Maintenance was completed on DG No. I and it was declared operable on February 16, 1989. Maintenance was then performed on DG No. 2, and it was declared operable on February 1 Additionally, an NPPD investigation team consisting of the QA Division Manager, the CNS QA Manager, the Nuclear Overview Manager, and the Nuclear Licensing and Safety Manager assembled to evaluate the history and root cause of the DG No.1 failure. The team discovered that a thin-walled Nonconformance fitting Report (failure NCR) No.had occurred 16 was issued previousl on November 27, 1973, documenting a failed nipple in the control air system of DG No. 2. Corrective action for the NCR was to replace all fittings with thick-walled nipples in both DG This NCR was not discovered during root cause analysis for the January 17, 1989, fitting failure or for a previous air system failure which occurred on DG No. 2 on October 21, 1988. The licensee's program requires that NCRs be reviewed for only the last 5 years during root cause determinatio In addition, no changes had been made to the applicable drawings or specifications to require that thick-walled fittings be installed. The team also identified several other instances of vibration induced failures on both DGs. The team noted several other documents which indicated a continuing problem with vibration associated failures on diesel generators which, if they had been properly evaluated, could have prevented the failure in January 1989 or ensured that the subsequent repair would have been identical to the previous installation. The licensee has committed to implementing design modifications to move vibration sensitive instruments from the DG to instrument racks, and to upgrade tubing during the 1989 refueling outag . . -

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-5-An inoperable DG,in excess of 7 days was identified as a potential'

violation. The cause for the inoperability was~an inadequate replacement part installed after a previous DG failur The root cause was determined to be personnel error and inadequate corrective actions in response to previous failure . Exit Interview (30703)'

An exit interview was conducted February 16, 1989, with licensee I representatives (identified in paragraph 1). During this interview, the NRC inspectors reviewed the scope and findings of the inspection. The licensee did not identify as proprietary any information provided to, or reviewed by, the inspector <

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