ML20086K536

AO 75-5:on 750118,electrical Failure Found of Operator Motor on RHR Throttling Reactor Injection Valve Mo 2-10-154B.Caused by Vibration During Valve Operation.Motor Replaced & Antirotation Strut & Key Realigned

ML20086K536
Person / Time
Site:	Peach Bottom
Issue date:	01/28/1975
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086K539	List: ML20086K536 ML20086K540
References
AO-75-5, NUDOCS 8401270219
Download: ML20086K536 (2)

Text

c PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET

, PHILADELPHIA. PA.19101 (21518414000 January 28, 1975 Mr. A. Giambusso _--

Director, Division of Reactor Projects Office of Nuclear Reactor Regulations ,

U. S. Nuclear Regulatory Commission --

Washington, DC. 20555 -

Dear Mr. Giambusso:

~ -

Subject:

Abnormal Occurrence The following occurrence was reported to Mr. E. J. Brunner, N.R.C. Region 1 Regulatory Operations Of fice on January 18, 1975 Written notification was made to Mr. James P. O'Reilly, Region 1

- Regulatory Operations Of fice on January 20, 1975 In accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR-44 for Uni t 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:

3 5.A.3 Report No.: 50-277-75-5 Report Date: January 28, 1975 Occurrence Date: January 18, 1975 Facility: Peach Bottom Atcntic Fower Station R.D. I, Delta, Pennsy vania l 17314 Identification of Occurrence:

Electrical failure of the operator motor on the RHR throttling reactor injection valve (M0 2-10-1548).

Conditions Prior to Occurrence:

Reactor shutdown an'd depressurized with the RHR operating in the shutdown cooling modo.

Description of Occurrence:

s While opening the valve from the control room, the l imi t or que operator motor. failed electrically, tripping its circuit breaker.

~

F140tR70219 750128 } 11 $

PDR J '10CK 05000277 -

S PDR

.Mr. A. Giambusso January 28, 1975 Page 2 Designation of Apparent Cuase of Occurrence:

. Vibration during valve operation had loosened the set screw holding the~ valve shaft anti-rotation strut key. The anti-rotation key had slipped down and jammed between the valve stem and the packing follower, resulting in an increased loading on the operator. Because the torque switch is inoperative during the opening stroke, the motor failure was probably due to the increased mechanical load on the opera-tor.

Analysis of Occurrence: -

At the time of the failure the reactor was in the cold shut-down condition. The "A" RH3 loop was available for shutdown cooling,

, and if required, the "B" loop could have been used because the M0 10-1548 valve was in the partially open position when the motor failed. The safety significance of this incident is minimal because the vibration which initiated the failure exists only when the valve is being throttled.

During reactor operation this valve is in the full open position.

~ Corrective Action:

The motor was replaced and the anti-rotation strut and key realigned. The set screw was staked in place and the other three MO 10-154 valves were inspected for loose set screws and anti-rotation 3Luts.

Failure' Data:

There have been no identical failures of this type at Peach Bottom, but a motor failure on this operator was reported in Abnormal Occurrence Report 50-277-74-32.

Very truly yours, M J. Cooney Ass't Gen' t Superintendent Generation Division i

cc: Mr. J. P. O'Reilly

_ Director, Region 1

, U. S. Nuclear Regulatory Commission 631 Park Avenue

King of Prussia, PA 19406