ML20086J141

AO 74-36:741210,Limitorque Motor Support on Hpsw/Rhr HX Discharge Valve MO-3-10-89A Failed.Caused by Broken Cap Screws Which Hold Limitorque Motor Operator to Adapter Plate.Valve Disassembled for Internal Insp

ML20086J141
Person / Time
Site:	Peach Bottom
Issue date:	12/20/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086J144	List: ML20086J141 ML20086J147
References
AO-74-36, NUDOCS 8401230246
Download: ML20086J141 (2)

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PHILADELPHIA ELECTRIC COMPANY

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December 20, 1974 Mr. A. Giambusso l

Deputy Director of Reactor Projects United States Atomic Energy Commission f, Directorate of Licensing '

Washington, DC 20545 i s

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Walt Baunack, b A.E.C. Region 1 Regulatory Operations Offise on December 10, 1974.

Written notification was made to Mr. James P. O'Rei1ly, Region 1 Regu-latory Operations Office on December 10, 1974. In accordance with Section 6.7 2.A of the Technical Speci fications, Appendix A of OPR-56 for Unit 3 Pctch Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence. r

Reference:

License Number DPR-56 Technical Specification

Reference:

3 5.8 Report No.: 50-278-74-36 Report Date: December 20, 1974 Occurrence Date: December 10, 1974 ,

Facility:

Peach Bottom Atomic Power Station R. D. /il, Delta, Pennsylvania 17314 Identification of Occurrence:

Failure

_ discharge valve of limitorque motor support- on HPSW/RHR heat . exchanger MO-3-10-83A.

C_onditions Prior to Occurrence:' -

Unit shutdown. RHR shutdown - cooling mode in service.

Description of Occurrence:

During the operation of valve MO-3-10189A in connection with placing the RHR and HPSW system in service to cool the primary system with the reactor. shutdown, the subject valve motor support f ailed. The valve at this-time was-in a throttled position. i 8401230246 741220 #

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Mr. A. Giambusso ,_

December 20, 1974 I ) Page 2 v

Designation of Apparent Cause of Occurrence:

During operation these valves are subject to vibration. The cap screws which hold the limitorque motor operator to an adapter plate were found to be broken.

Analysis of Occurrence:

The f ailure of the cap screws render the valve inoperable.

In this case the valve failed in a partially throttled position but very close to full open. Adequate decay heat removal capability was available using the other RHR heat exchangers. Investigation revealed that the valve stem was bent. Pending arrival of a new stem, the operator was reinstalled and the valve manually throttled to provide the correct HPCW flow. Once the correct flow was obtained, tnc oper a-tor handwheel was chained and locked in position. With all four con-tainment cooling subsystem loops availabic, a plant startup was initi-ated. Minimal safety significance is attached to this failure.

Corrective Action:

The valve will be disassembled for a canplete internal in-spection, and the stem straightened or replaced. The motor will be re-moved and tested. The operator will be remounted using high tensile strength cap screws, and secured with LOC-TITE. Inspection of the re-maining valves in the same service is in progress. The Philadelphia Electric Company, Mcchanical Engineering Division in concert with the Architect Engineer is investigating means of reducing vibration on this system.

Failure Data:

Similar dif ficulties have been reported as Abnormal Occurrence Report Numbers 50-277-74-53, 50-278-74-28 and 50-278-74-35 Very truly yours, f ,- f),/,ff w f R. D. Meycr General Superintendent Generation Division cc: Mr. J. P. O'Reilly Director, Region i U. S. Atomic Energy Commissi'n o 631 Park Avenue King of Prussia, PA 19406 t .