ML20148F980

Final Deficiency Rept CP-87-137 Re Loose Diesel Generator Governor HX Internal Baffle Plate.Initially Reported on 871230.Caused by Vendor Design Error.Deficient HX Replaced W/Hx Utilizing Vendor Revised Internals

ML20148F980
Person / Time
Site:	Comanche Peak
Issue date:	01/20/1988
From:	Counsil W, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
CP-87-137, TXX-88127, NUDOCS 8801260370
Download: ML20148F980 (2)

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DESN,"21, January 20, 1988 V. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION DOCKET NOS. 50-445 AND 50-446 DIESEL GENERATOR GOVERNOR HEAT EXCHANGER SDAR: CP-87-137 (FINAL REPORT)

Gentlemen:

On December 30, 1987, we verbally notified your staff of a deficiency involving the diesel generator (DG) governor heat exchanger which could reduce the cooling capacity of the heat exchanger. We have conservatively deemed this issue reportable pursuant to the provisions of 10CFR50.55(e). The required information follows.

DESCRIPTION The diesel generator governor oil cooler consists of two concentrically wound helical coils with water flowing through the inner coil and oil through the outer coil. A baffle plate prevents water flow through the center area (core) of the cooler and causes the water to flow through the inner helical coil. In a specific installation (the Unit 1 Train "B" Diesel Generator) the baffle

plate was observed to be loose.

The baffle plate directs coolant flow into the inner helical path for more efficient cooling of the governor oil. Although cooling water would continue

to flow through the core of the heat exchanger instead of through the inner coil, if the baffle ) late had failed in the (worst case) horizontal position inside the core of t1e inner helical coil, it is indeterminate whether or not the required amount of heat transfer would occur.

The cause of this condition appears to be an error in vendor design or fabrication of the cooler and internal baffle plate (which was soldered or brazed in place). This joint failed and the baffle plate broke loose.

This condition was potentially applicable to other similar safety-related governor oil coolers of the same design and manufacturer. Our evaluation has confined the deficiency to the affected DG installation and the turbine driven auxiliary feedwater pump turbine governor.

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ADOCK 05000445 DCD

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TXX-88127 January 20, 1988

'Page 2-of 2 SAFETY IMPLICATIONS A loss of diesel generator governor oil heat exchanger cooling capacity affects governor cil temperature and the speed control of the diesel ger.erator. These conditions could result in the inability of the diesel gen 1rator to supply emergency electrical power to safety-related components following postulated accidents. Speed control of the turbine driven auxiliary feedwater pump may also have been affected and resulted in the loss of auxiliary feedwater under some accident conditions.

CORREC'.IVE AC7 ION, The deficient DG heat exchanger has been replaced with a heat exchanger uti.izing iiternals with a revised desior, developed by the vendor. The remaining installations will be replaced during the next scheduled governor oil clunges. No further actions are required.

Very truly yours, W .c,. c n u W. G. Coun il By:

D. R. Woodlan Supervisor, Docket Licensing MCP/grr c-Mr. R. D. Martin, Region IV Resident inspectors, CPSES (3) l l

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