AECM-86-0050, Final Part 21 & Deficiency Rept RD-85/04 Re Inadequate Cooling in Tdi Diesel Generator Control Panels.Initially Reported on 850429.Linear Reactors on Panels Replaced & Cooling Air Supply Installed

Final Part 21 & Deficiency Rept RD-85/04 Re Inadequate Cooling in Tdi Diesel Generator Control Panels.Initially Reported on 850429.Linear Reactors on Panels Replaced & Cooling Air Supply Installed

ML20214D728
Person / Time
Site:	Grand Gulf
Issue date:	02/14/1986
From:	Dale L MISSISSIPPI POWER & LIGHT CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21-86, REF-PT21-86-141-000 AECM-86-0050, AECM-86-50, PT21-86-141, PT21-86-141-000, RD-85-04, RD-85-4, NUDOCS 8603050448
Download: ML20214D728 (6)

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's MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi M P. O. B O X 16 4 0, J A C K S O N, MISSISSIPPI 39215-1640 February 14, 1986 NUCLE AR LICEN5ING & SAFETY DEPARTMENT m

U. S. Nuclear Regulatory Commission Region II "

101 Marietta St., N.W. Suite 2900 Atlanta, Georgia 30323 a

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Attention: Dr. J. Nelson Grace, Regional Administrator c.n cu

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 File: 0260/0511/0512 RD-85/04, Final Report -

Inadequate Cooling in TDI Diesel Generator Control Panels AECM-86/0050 On April 29, 1985, Mississippi Power & Light Company (MP&L) notified Mr. Vince Panciera of your office of a Reportable Deficiency at Grand Gulf Nuclear Station Units I and 2. The deficiency concerns the failure of a linear reactor in the control panel of the Unit i Division II Diesel Generator attributed to thermal aging. MP&L has concluded that inadequate ventilation (air flow) of the diesel generator control panel was the major contributing cause of the thermal aging.

This deficiency was determined to be reportabic under the provisions of 10CFR21 for Units I and 2 and under the provisions of 10CFR50.55(e) for Unit

2. Attached is a final report on the subject.

Yours truly, L. F. Dale Director JRM/GHD/SHH:

Attachment cc: (See Next Page)

G603050448 860214 PDR ADOCK 05000416 S PDR 1

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Member Middle South Utilities System  !

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AECM-86/0050 Page 2 cc: Mr. O. D. Kingsley, Jr. (w/a)

Mr. T. H. Cloninger (w/a)

Mr. N. S. Reynolds (w/a)

Mr. H. L. Thomas (w/o)

Mr. R. C. Butcher (w/a)

Mr. James M. Taylor, Director (w/a) i Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 i

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Attach:cnt to AECM-86/0050 Final 10CFR21/50.55(e) Report

1. Name and address of the individual informing the commission:

O. D. Kingsley Vice President Nuclear Operations P. O. Box 1640 Jackson, Mississippi 39205

2. Identification of the facility ... which ... contains a deficiency:

Grand Gulf Nuclear Station (GGNS) Units 1 and 2 Port Gibson, Mississippi 39150

3. Identification of the firm ... supplying the basic component which ...

contains a deficiency:

The control panels which contain the linear reactors were fabricated and assembled by RTE Delta Corp.

The control panels were supplied to GGNS as a part of the Emergency Diesel Generator by Transamerica Delaval, Inc. , Oakland, California.

4. Nature of the deficiency ... and the safety hazard which ... could be created by such a deficiency ...

1 A. Description of the Deficiency During a maintenance run of the Unit 1 Division II Diesel Gene'rator, ,

the local operator noticed smoke coming from the local control panel.

The local operator informed the control room operator who reduced the i engine load and subsequently shutdown the diesel generator. ,

An investigation was performed and it was determined that the phase "C" linear reactor (LR-3) had overheated. This excessive overheating had caused a breakdown of the reactor insulation which subsequently burned. The A and B phase linear reactor (LR-1 and LR-2) did not fail; however, each had visual indications of overheating.

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Attechmsnt to AECM-86/0050 A similar failure occurred in June 1984 when the phase "B" linear reactor on the Division I Diesel Generator failed (Special Report 84-028). This failure was attributed to premature thermal aging. The thermal aging had been attributed to excessive testing of the Division I Diesel Generator. The Division II control panel linear reactors were also visually inspected at this time and no evidence of accelerated thermal aging was reported. The Division I failure had undergone an evaluation of 10CFR21 applicability. Based on inf ornation available at the time, it was determined that a defect in the linear reactors did not exist and that the failure waa caused by excessive testing of the Diesel Generator at high loads. However, additicnal testing and recent vendor information obtained has enabled MP&L to conclude that a major contributing cause of thermal aging on the linear reactors in the diesel generator control panels was due to l

inadequate ventilation (air flow) in the control panel.

! The linear reactors are a power component in the diesel generator excitation system. These electromagnetic devices cause a 30 degree phase shift in the potential output of the 3 phase potential transformer (T1) to compound it to the power output of the exciter current transformers (CT1, CT2, and CT3). In summary, the linear reactors are used to obtain voltage regulation in the excitation circuit.

Had the phase "C" linear reactor shorted to ground, the differential relay would have caused a protective engine trip due to loss of generator excitation.

B. Analysis of Safety Implications:

i The Division I and II control panels are considered redundant basic components, as defined in NUREC-0302. Therefore, it is conservatively postulated that a failure of both Division I and II could potentially exist. This failure coincident with a single active failura of Division III could result in a loss of safety function necessary to mitigate the consequences of an accident to the extent that a reduction in the degree of protection provided to public health and safety could exist. ,

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5. The date on which the information of such deficiency ... was obtained:

Mississippi Power and Light received information of the deficiency on March 2, 1985. An evaluation under the guidelines of 10CFR21 was completed on April 26, 1985.

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Attachssnt to AECM-86/0050

6. In the case of the basic component ... the number and location of all such components:

Unit 1 There is one RTE Delta control panel located in each of the Division I and II Diesel Generator Rooms.

Unit 2 The Division I and II control panels are presently stored in the warehouse.

MP&L has no knowledge of the existence or location of other defective equipment.

7. The cort ective action which has been taken . . . the name of the individual responsible for the action; and the length of time that has been ... taken to complete the action.

A. Corrective Actions Taken Unit 1

1. The linear reactors were replaced per Maintenance Work Orders, MWO #E44491 for Division I and MWO #E51409 for Division II.

2. Design Change Package (DCP) #84/4063, was issued to install a cooling air supply to the Division I and II control panels.

DCP #84/4063 was implemented per Maintenance Work Orders,

, MWO #F52304, MWO #F52305, MWO #F52354 and MWO #F52460 and Change Notices, CN X77-1 CN X77-2 and CN X77-3.

3. MP&L purchased (Purchase Order #M90677) six new linear reactors (TDI P/N 74033-102-17) from Transamerica Delaval Inc. which incorporated a vendor design enhancement to reduce the operating temperature of the Ifnear reactors by increasing the air flow area around the windings. The new linear reactors were installed per Maintenance Work Orders, MWO #E60584 for Division I and MWO

1. E60618 for Division II.

4 The subsequent ifnear reactor operating temperature readings revealed the temperature was reduced by approximately 180*F.

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I Atteche:nt to i AECM-86/0050 i

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1. The Unit 2 corrective actions will be finalized upon resumption l

of normal construction activities.

2. Bechtel has issued Management Corrective Action Report MCAR #157 to track the Unit 2 corrective actions. ,

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B. Responsible Individual l

0. D. Kingsley l

l Vice President, Nuclear Operations ,

j Mississippi Power & Light Company

C. Length of Time to Complete Actions Unit 1 4 i l The replacement of the linear reactors has been completed.

1 i Implementation of DCP #84/4063 to provide additional cooling has been completed.

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I The vendor design enhanced linear reactors have been installed.

l No further corrective actions are indicated nor are any planned for j] Unit 1 at this time.

Unit 2

Unit 2 corrective actions will be completed prior to Unit 2 fuel

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load.

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! 8. Any advice related to the deficiency ... that has been, is being, or will ,

j be given to purchasers or licensees l 1 l i As the deficiency did not originate with MP&L, it has no advice to offer.

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