05000416/LER-1983-107, Updated LER 83-107/03X-2:on 830726,during Test,Mounting Bolts for Div 1 Diesel Generator Turbocharger Found Loose or Broken & Associated Parts & Welds Cracked.Caused by Misaligned Turbocharger.Longer Bolts installed.W/840327 Lt

Updated LER 83-107/03X-2:on 830726,during Test,Mounting Bolts for Div 1 Diesel Generator Turbocharger Found Loose or Broken & Associated Parts & Welds Cracked.Caused by Misaligned Turbocharger.Longer Bolts installed.W/840327 Ltr

ML20087N882
Person / Time
Site:	Grand Gulf
Issue date:	03/27/1984
From:	Byrd R, Dale L MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AECM-84-0169, AECM-84-169, LER-83-107-03X, LER-83-107-3X, NUDOCS 8404050132
Download: ML20087N882 (5)

LER-2083-107, Updated LER 83-107/03X-2:on 830726,during Test,Mounting Bolts for Div 1 Diesel Generator Turbocharger Found Loose or Broken & Associated Parts & Welds Cracked.Caused by Misaligned Turbocharger.Longer Bolts installed.W/840327 Ltr

Event date:
Report date:
4162083107R00 - NRC Website

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EWGNT DASCRIPTtoII afeD PROSa8LE CONSEQUENCES h E lan 7/2&/B3. durino a test. the mountino bolts for a Div. I D/G turbo- l ra s s tcharger were found to be either loose or broken. During.this and j E l subsequent tests and inspections, associated parts and welds were  !

Q idiscovered cracked or broken. The requirewents of T.S. 3.8.1.2 were met.l u o IThe event had no effect on the health and safety of the public nor was l 8 lthere a threat to plant safety.__This is reported pursuant tc T.S. _ l

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NAME OF PMEFARER R. W. Eyrd PHOME:

Attachment to I AECM-84/0169 Page 2 of 3 Supplementary Information to LER 83-107/03 X-2 Misnissippi Power & Light Company Grand Gulf Nuclear Station - Unit 1 Docket No. 50-416 Technical Specification Involved: 4.8.1.1.3 Reported Under Technical Specification: 6.9.1.13.b Event Narrative On July 26, 1983, during a routine visual inspection 92 minutes into a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> surveillance test run of the Division I Diesel Generator, the bolts that hold the lef t bank turbocharger to its support or mounting plate were discovered to be either loose or broken. Four 5/18-11x2" SAE grade 5 capscrew bolts are used to mount the turbocharger. Two of the four bolts for the LB turbocharger >

were broken and the others were loose. One of the bolts had sheared off and the broken part remained in the LB turbocharger housing. All of the bolts, except the one sheared off, were replaced and torqued to 60 ft-lbs. No other damage was apparent.

As a precaution, the Division Il Diesel Generator turbocharger bolts were inspected. Two bolts were found loose, one on each turbocharger; in addition, two bolts on the LB turbocharger were not of the type specified by the manufacturer. The incorrect bolts were replaced and all the bolts werc _ ..

torqued to 60 ft-lbs.

On July 27, 1983, the Division I Diesel Generator was 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> into a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> surveillance test run when mounting bolts on the turbocharger were again inspected and found to be either loose or broken. The Diesel Generator was .

manually shutdown for repairs. Subsequent inspections and tests, including ~

short maintenance runs, over the next 3 weeks revealed the following:

1. cracked welds in the RB and LB intercooler adapters which are between the intercoolers and turbochargers,

2. a base metal crack (1" long) in the LB intercooler,

3. a through wall crack in the weld between the RB turbocharger and the cooling water discharge piping,

4. A through wall crack in the veld between the LB turbocharger and the cooling water discharge piping, and

5. two broken mounting bolts in the LB turbocharger.

The cracked welds were weld repaired. The LB turbocharger was replaced and the mounting bolts were changed from 5/8"-11x2" SAE grade 5 capscrew bolts to 1 5/8"-11x2h" SAE grade 3 capscrew bolts. Flat washers were added under the existing lock washers. The turbocharger vas realigned to eliminate an air gap between it and the mounting base.

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• Attechzant to AECM-84/0169 Page 3 of 3

-The micalignneat is believed to be the root cause of the bolt failures. The bolt failures allowed relative movement between the turbocharger and its e

mounting base plate; the resulting vibration caused fatigue cracking in the attached piping and intercooler adapters. All; applicable corrective actions have also been performed on the' Division II Diesel Generator.

A spot check radiography of 10 butt welds at random locations on the jacket water lube oil, and starting air systems was performed on the Division I Diesel Generator. One weld which did not meet acceptance criteria, was weld repaired.

t On August 21, 1983, the Division I Diesel Genecator completed a successful 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> maintenance run with no problems. It was restarted 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> later to begin a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> surveillance test. Approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> later, a second

'thru wall crack developed in the weld between the LB turbocharger and the cooling water discharge piping. This was weld repaired and is attributable to the conditions generated by the original turbocharger bolt problem._ The torque.was. checked on all of the turbocharger mounting bolts after 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of operation'since che bolt change and there was no decrease in five bolts and no appreciable change in the other three.

On August 30, 1983 (Reference LER 83-136/03 X-2), a base metal crack vas discovered in the LB turbocharger intercooler adapter 98 minutes into : 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. surveillance test. The crack was weld repaired. This event was also <

attributed to the conditions generated by the original bolt problem.

A design change vari initiated to replace all of the coolant piping associated with'the turbochargers. This waL. performed during the diesel repairs as a result _of the fuel oil fire of September 4, 1983 (Reference LER 83-126/01 T-0). In addition, all equipment alignments associated wita the turbocharger were checked and corrected as necessary.

During subsequent . tests on January 31 ~and February 10, 1984, bolts again failed on the Division I Diesel Generator LB turbocharget (reported in Special Report 84-007/0). The failures ~ on January 31 and 1%bruary 10 were again attributed to misalignment of the turbocharger. A Maintenance Work Order (MWO) utilizing Special Instructions. designed to preclude misalignment was

'impicmented ,The alignment is now corrected.

,4 __

P MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. BOX 1640 J ACKSON MISSISSlPPI 39205 84 mR 2 March A!0 :27,0 0

1984 NUCLEAR PRODUCTION DEPARTMENT U.S. Nuclear Regulatory Commission Region 11 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30303 Attention: Mr. J. P. O'Reilly, Regional Administrator

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-13 File: 0260/L-835.0 Update Report - Mounting Bolts on Division I Diesel Generator Turbocharger Found Loose or Broken LER 83-107/03 X-2 AECM-84/0169 This letter submits an update to previous reports submitted on August 26, 1983 and October 24, 1983. The event for which the report was submitted occurred on July 26, 1983, when during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test run some of the mounting bolts for a Division I Diesel Generator turbocharger were found to be either loose or broken. During subsequent tests and inspections, cracked welds wue found on the intereccler adapter between the intercooler and turbocharger bnd in the cooling water outlet piping. The diesel generator had been loaded to greater than 50% for longer than I hour, therefore, this was considered a valid successful test pursuant to Regulatory Position C.2.e.(3) of Regulatory Guide 1.108. This was reported pursuant to Technical Specification 6.9.1.13.b.

Our investigation into the cause of the event and corrective action to prevent recurrence is complete. This is a final report. Attached is LEP 83-107/03 X-2 with Supplementary Information.

Yours truly, L. F. Dale Manager of Nuclear Services EBS/SHE:rg Attachment ec: See next page CIAl capf';

1E cc Member Middle South Utilities System yy

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.AECM-84/0169-

' ap 2 gj MISSISSIPPI POWER O Ll2HT COMPANY s ?' "' -,

cc: 'Mr. J. B.-Richard'(w/a)-

Mr. R. B. McGehee (w/o)-

Mr. T. B. Conner (w/o)

Mr..G. B. Taylor (w/o)

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Mr. Richard C. DeYoung, Director (w/a)

_ T" Office of Inspection & Enforcement '

U. S. Nuclear Regulatory Commission .

' Washington .D. C. 20555 r:

Document. Control Desk (w/a)

U. S. Nuclear Regulatory Commission I

Washington, D. C. 20555 f a

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