ML20086F896

AO 75-73:on 751113,leak Observed on RHR Sys Relief Valve RV-35B.Caused by Throttling of MO-2-10-154B Valve Resulting in Crack.Weld Repairs Will Be Made to Relief Valve in Accordance W/Approved Procedures

ML20086F896
Person / Time
Site:	Peach Bottom
Issue date:	11/21/1975
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Boyd R Office of Nuclear Reactor Regulation
Shared Package
ML20086F900	List: ML20086F896 ML20086F902
References
AO-75-73, NUDOCS 8401090634
Download: ML20086F896 (2)

Text

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PHILADELPHIA ELECTRIC COMPANY 2301 MARKEEr STREET PHILADELPHI A. PA.19101 i

(215)0414o00 November 21, 1975 Mr. Roger S. Boyd Acting Director Division of Reactor Licensing Office of Nuclear Reactor Regulations United States Nucicar Regulatory Commission Washington, DC 20555

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. Walt Baunack, Region 1, Of fice of Inspection and Enforcement, United States Nuclear Regulatory Commission on November 14, 1975 Written notification was made to Mr. James P. O'Reilly, Region 1, Of fice of Inspection and Enforcement, United States Nuclear Regulatory Commission on Novenber 14, 1975 In accordance with Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Reactor Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44 Technical Specification

Reference:

1.0.0 5 Report No.: 50-277-75-73 Report Date: November 21, 1975 Occurrence Date: November 13, 1975 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:

Leak on body of RHR system relief valve, RV-358.

1 Conditions Prior to Occurrence: '

Reactor shutdown and depressuri zed. Reactor . head removed and "B" RiiR loop operating in shutdown cooling mode.

Description of Occurrence:

With the "B" RHR loop operating in the shutdown cooling mode, a leak was observed on the body of RV-358. The leak was initially reported as being located at the th_rcaded joint between the two portions of the valve 8401090634 751121 PDR ADOCK 05000277 s PDR 1340 g:

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Mr. Roger S. Boyd , 50-277-75-73 November 21, 1975 Page 2 body. However, removal and disassembly of the valve revealed that a crack on the valve base at the transition to the nipple was responsible f or the Icak.

Designation of Apparent Cause of Occurrence:

Because the RHR system was operating in the shutdown cooling mode with low heat loads, it was necessary to throttic the M0-2 .0-1548 7 valve. This throttling caused vibrati_on which resulted in.the cr.ack.

Analysi s of Occurrence:

The safety implications of this occurrence are minimal since the leakage did not impair the RHR system's ability to deliver design flow. Liquid effluent f rom the Icak was safely contained in the immediate arca in the torus room. The leak was external to the isolation valves.

Corrective Action:

Weld repairs will be made to the relief valve in accordance with approved procedures. In addition, Philadelphia Electric Company Engineering Department has reviewed the supports for this valve and has recommended additional bracing. This bracing will be installed af ter approval of the original pipe support design organization is obtained.

Failure Data:

50-277-75-71 and 50-277-75-72.

Very truly yours,

/

. J. ooney Sup intendent Generation Division-Nuclear cc: Mr. J. P. O'Reilly Director, Region 1 Office of Inspection and Enforcerent U.S. Nuclear Regulatory Commission 631 Park Avenue i

King of Prussia, PA 19406 f

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