ML20086G169

Environ RO 76-27:on 760507,three Cooling Towers Became Simultaneously Inoperable.Caused by Bolts Holding Impeller Housing to Pump Diffuser Section Failing.Investigation Continuing to Determine Corrective Action

ML20086G169
Person / Time
Site:	Peach Bottom
Issue date:	05/17/1976
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Stello V Office of Nuclear Reactor Regulation
References
RO-76-27, NUDOCS 8401100106
Download: ML20086G169 (2)

Text

. _ _ . ________________________________ _ _ _ _ _ _ .

PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET -

PHILADELPHIA. PA.19101 (2151 841-4o0o May 17, 1976 .u,.

gs - . .~ . )

Mr. Victor Stello, Jr. s (A l Director g Y' Division of Operating Reactors -

Office of Nuclear Reactor Regulations 1

~

United States Nuclear Regulatory Comission ~

Mgy g I9705 _

Washington, D.C. 20555 A

Ddd'gooer

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Subject:

Envi ronmental Deviation m ; .: \ \

~~

The following deviation was reported to Mr. Walt Baunack, Region 1 Office of Inspection and Enforcement, United States Nuclear Regulatory Comission on May 7,1976.

Reference:

LicenseNumber,DPR-44/56 Envi ronmental Technical Speci fication Section 2.1 Report No.: 50-277/278-76-27 Report Date: May 17, 1976 Deviation Date: May 7, 1976 Faci li ty: Peach Bottom Atomic Power Station Units 2 and 3 _ .

R.D. #1, Delta, PA 17314 Identi fication of Deviation:

Three cooling towers simultaneously inoperable.

Condi tions Prior to Deviation:

Unit 3 operating at 85% power. Unit 2 of f for refueling outage. The "A" and "B" cooling towers were out of service due to previous lif t pump failures. River flow was about 33,000 CFS.

Description of Deviation:

"C" cooling tower lift pump failed making 3 cooling towers inoperable.

Designation of Apparent Cause of Deviation:

Bolts holding the impeller housing to the pump diffuser section failed causing the housing to fall to the bottom of the lift pump pi t.

e401100106 760517 50 %

PDR ADOCK 05000277 S PDR ~

COM SENT REGION _>

.__________ __ ____ ____. _ _ _ _ _ _ _ _ _ _ _ _ ._ ___ ___________ 2

.?- .

o o Mr. Victor Stello, Jr. , .-

50-277/278-76-27 May 17, 1976 Page 2 Analysis of Deviation:

Differential temperatures between the Pennsylvania-Maryland State Line and Holtwood Dam remain within Pennsylvania State limits.

High river flow and single unit operation during this period minimized the thermal impact of this deviation. Shortly after failure of the "C" cooling tower, Unit 3 was shutdown due to other plant equipment di f fi cu l ti es.

Corrective Action:

Investigative work continues at this time to determine the cause of the pump failures. The Philadelphia Electric Company Engineering Department and several consultants are involved in a co-ordinated effort to identify the cause of this failure and determine a course of action to prevent recurrence of this type of failure.

Operation of Unit 3 will be administrative 1y limited to less than 20%

of rated thermal power until the Environmental Technical Speci fications a re modi fi ed.

Failure Data:

A similar environmental deviation was reported in Environ-mental Deviation Report 50-277/278-76-24.

Very truly yours, M. ,. Cooney Su rintendent Generation Division - Nuclear cc Mr. J. P. O'Rei 11y NRC, Region 1

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