05000348/LER-1980-073-01, /01T-0:on 801126,during Insp of Msivs,Damage to Valve Disc Bolt Holes & Disc Arm Bolting on Three Valves Was Revealed.Caused by Design Deficiency & Inadequate Locking Devices on Bolting.Discs Will Be Repaired or Replaced

/01T-0:on 801126,during Insp of Msivs,Damage to Valve Disc Bolt Holes & Disc Arm Bolting on Three Valves Was Revealed.Caused by Design Deficiency & Inadequate Locking Devices on Bolting.Discs Will Be Repaired or Replaced

ML19351E617
Person / Time
Site:	Farley
Issue date:	12/04/1980
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19351E611	List: 05000348/LER-1980-073, Forwards LER 80-073/01T-0 05000348/LER-1980-073-01, /01T-0:on 801126,during Insp of Msivs,Damage to Valve Disc Bolt Holes & Disc Arm Bolting on Three Valves Was Revealed.Caused by Design Deficiency & Inadequate Locking Devices on Bolting.Discs Will Be Repaired or Replaced
References
LER-80-073-01T, LER-80-73-1T, NUDOCS 8012100526
Download: ML19351E617 (2)

LER-1980-073, /01T-0:on 801126,during Insp of Msivs,Damage to Valve Disc Bolt Holes & Disc Arm Bolting on Three Valves Was Revealed.Caused by Design Deficiency & Inadequate Locking Devices on Bolting.Discs Will Be Repaired or Replaced

Event date:
Report date:
3481980073R01 - NRC Website

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'Q"g *-{A = i 7 ( 9 10 PUSUCITv to 8012100 [J6- " "' "5' EE]tS5utnLNJhl otsCmirficN ,,,,,,,,,,,,p NA u m NAME OF PnCPARER tJ. G. Hairston. III pgny,7__ @ M N M _, _

l. . >.. ~, 1 e ATTACHMENT TO IIR 80-073/0lT-0 The following information is submitted in accordance with 10 CFR Part 21. 1. Defective Basic Component - Atwood & Morrill Co., Inc. supplied Main Steam Swing Disc Trip Valves (32", 600# ANSI, A&M Dwg. 21261-H). These valves are used as Main Steam Isolation Valves (MSIV's) in the Main Steam Systems for Unit I and 2 at FNP. 2. Nature of Problem - Inadequate locking devices on the MSIV disc arm bolting allowed the disc arm studs and nuts to vibrate loose, causing damage to the studs and disc bolt holes. If gone undetected, this condition could have resulted in a malfunction of the MSIV. 3. Background Data - Atwood & Morrill Co., Inc. notitied Alabama Power Company of a potential problem with the locking mechanism on the MSIV disc arm bolting and recommended that APCo perform an inspection of the MSIV disc arm bolting. As a result of this inspection, damage to the valve disc bolt holes and disc arm bolting on the three downstream MSlV's was revealed. This damage resulted from inadequate locking devices on the disc arm bolting, allowing the studs and nuts to vibrate loose. Although no studs were missing, one nut was missing, several disc bolt holes were damaged and one stad was worn nearly in half. Loose nuts and studs were also found on the upstream MSIV's, but no damage to the disc bolt holes or studs had occurred. All Main Steam Isolation Valves were still operable. However, engineering review on 11/26/80 concluded that, if not corrected, this condition could have led to a valve malfunction. 4. Degree of Problem - The affected valves are the MSIV's in the Unit 1 and 2 Main Steam Systems (total of 12 valves). The inadequate locking device on the disc arm bolting could compromise the ability of the MSIV's to perform their intended function. That is, although this condition has not made any safety-related equipment inoperable, it could be considered to constitute a potential loss of safety function of a basic component and a reduction in the degree of protection provided to safety-related systems. 5. Corrective Action ~- On Unit 1, the damaged valve discs will be repaired or replaced. A design change is being implemented which will provide a positive locking arrangement for the disc arm bolting. This work will te complete prior to entry into Mode 4. On Unit 2, the design change described above.will be implemented prior to initial startup. f W }}