05000237/LER-1979-054-03, /03L-0:on 791004,portion of Drywell Ventilating Line 2-1605-10 Declared Inoperable Due to Degraded Pipe Supports.Caused by Insufficient Thread Engagement & Missing Nuts,Causing Hanger Supports to Become Loose.Nuts Replaced

/03L-0:on 791004,portion of Drywell Ventilating Line 2-1605-10 Declared Inoperable Due to Degraded Pipe Supports.Caused by Insufficient Thread Engagement & Missing Nuts,Causing Hanger Supports to Become Loose.Nuts Replaced

ML17174A109
Person / Time
Site:	Dresden
Issue date:	10/29/1979
From:	Badran S COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17174A110	List: 05000237/LER-1979-054, Forwards LER 79-054/03L-0 05000237/LER-1979-054-03, /03L-0:on 791004,portion of Drywell Ventilating Line 2-1605-10 Declared Inoperable Due to Degraded Pipe Supports.Caused by Insufficient Thread Engagement & Missing Nuts,Causing Hanger Supports to Become Loose.Nuts Replaced
References
LER-79-054-03L, LER-79-54-3L, NUDOCS 7911060388
Download: ML17174A109 (2)

LER-1979-054, /03L-0:on 791004,portion of Drywell Ventilating Line 2-1605-10 Declared Inoperable Due to Degraded Pipe Supports.Caused by Insufficient Thread Engagement & Missing Nuts,Causing Hanger Supports to Become Loose.Nuts Replaced

Event date:
Report date:
2371979054R03 - NRC Website

text

Commone1th Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr //79-862 October 26, 1979 James G. Keppler, Regional Director Directo~ate.of Regulatory Operations - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, 60137 Reportable Occurrence Report #79-54/031 Docket #050-237.

. is hereby submitted to your office in accordance. with Dresden Nuclear Power Station Technical Specification 6.6.B.Z':::Cb) conditions leading. to operation in a degraded mode permitted by a limiting condition for operation or plant shutdown re-quired by a limiting condition for operatio~.

Dresden ~uclear Power Station BBS:lcg Enclosure cc: *Director of Inspection & Enforcement Director of Management Information & Program Control File/NRC l?~

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U.S. NUCLEAR REGULATOHY COMMISSIUN LICENSEE EVENT REPORT CONTROL BLOCK:.__-.L.. _

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• During normal operation, a portion of the drywell ventilating line 2-1605-10 was

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IT:ill declared inoperable as a result of degraded pipe hanger supports found during I.E.Bulletin 19-74 inspections.

To ensure primary containment integrity was maintained during repairs, drywell and torus vent line isolation valves were kept in closed position.

Therefore, the safety significance was minimal.

This is the first failure of its kind which required the system to be inoperable.

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43 44 47 DJ)) I Due to vibration after construction, the piping hanger supports were found to have ITIJ] I bolts with insufficient-thread engagement and. missing nuts, causing the hanger supports to become loose.

Missing nuts were replaced and lock nuts were utilized rJ:II] I to prevent reoccurrence. Proper thread engagement of remaining bolts was verified.

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FACILITY STATUS

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