ML20084H765
| ML20084H765 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/22/1974 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084H769 | List: |
| References | |
| AO-BFAO-7428W, NUDOCS 8305050039 | |
| Download: ML20084H765 (3) | |
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TENNESSEE VALL CHATTANOOGA, TENNi2SSEEY AUTHC AITY CT } q\\
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Mr. John F. O'Learf, Director I
Directorate of Licensing Office of Regulation U.S. Atomic Energy Co= mission Washington, DC 20545
Dear Mr. O' Leary:
TETITESSEE VALLEY AUTHORITY - BRO',iHS FERRY ITUCLEAR PLANT UHIT 1 -
DOC'ET ITO. 50-259 - FACILITY OPERATING LICEIISE DPR ABNORMAL r
OCCURIC;CE REPORT BFAO-7428U The enclosed report is to provide details concerning a broken yoko which was discovered on the R'IR loop I torus spray valve, FCV 74-58, and is submitted in accordence with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 This event occurred on Browns Ferry Nuclear Plant unit 1 on May 12, 1974.
Very truly yours, TENNESSEE VALLEY AUTHORITY 0 I/7WW
'O E. F. Thonas
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Director of Power Production
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I'a. Horman C. Foseley, Director
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ABNORMAL OCCURRE!!CE REPORT
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-Report No.: BFAO-7428W 4
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Report Date: May 22, 1974 L
2 Occurrence Date: May 12, 1 W4 k.
gg' 'Q Facility: Browns Ferry Nuclear Plant unit 1
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Identification of Occurrence
' [,5N At approximately 2:00 p.m. on May 12,1W4, a broken yoke was discovered on the RHR loop I torus spray valve, FCV 74-58.
Conditions Prior to Occurrence The unit 1 reactor was in the cold shutdown condition.
Description of Occurrence While draining a section of the RHR line to permit repair work, torus spray valve FCV 74-58 tripped out electrically when an atte=pt was made to operate the valve.
Initial investigation indicated the valve was operating norml17 and not drawing excessive motor current when coerated from the control room. A chort time later the valve operator on FCV 74-53 was found separated from the valve stem.
Designation of Atuarent Cause of Occurrence An examnanon or -he yoke indicated the apparent cause of the failure to be an insufficient a=ount of weld or overstress of the weld.
Corrective Action A bonnet and motor operator frem a similar unit 3 valve were obtained and instc11cd.
Post-installation operation end leak checks were performed with satisfactory results. All other si=ilar welded yoke valves were inspected visually and found in satisfactory condition. An analysis is being performed to verify this type of
. yoke's ability to withstend the imposed stresses.
Analvcis of Occurrence The unit was in the cold shutdown condition, and torus sprey operation was not required.
If torus sprey had been required, water could have been supplied through valve FCV 74-72.
J Failure Data Valves FCV 74-58 and FCV 74-72 were originally supplied to TVA from the manufacturer with Limitorque SL3-000 operators. These operators were found to be too small and were replacedwith larger Limitorque operators size SLS-00.
On May 28, 1973, which was after the larger Limitorque operators had been installed, it was discovered that the Limitorque mounting bolts on the operators for valves FCV 74-58 and.
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Failure Data (continued)
FCV 74-72 had failed. Fer reco=endation of the =anufacturer (the Walworth Co=pany) and with the concurrence of General Electric Co=pany, the yoke plates on valves FCV74-58andFCV74-72weremodifiedfromusing5/16"boltstousing5/8" bolts to secure the Limitorque operator to the valve. The 5/8" bolts are nor n11y used for counting the larger sized Li=itorque operators. This information was previously submitted to F. E. Kruesi by J. E. Gilleland in a letter dated July 3, 1973, concerning a reportable deficiency identified as DDN 144.
The nameplate data for valve FCV 74-58 i~s as fonows:
Walworth Company Figure No. 52811E Size - 4" ASA - 300 @ 800 F. WoG Body - WCB Stem - CR13 Disc - CR13 Seat - N1Cn Serial No. 531542
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