ML19210C684

LER 79-033/01T-0:on 791020,piping Restraint 1/2-7509-R149 Had Safety Factor of Less than Two.Standby Gas Treatment Sys a & B Declared Inoperable.Caused by Improper Design Safety Factors.Restraint Modified

ML19210C684
Person / Time
Site:	Quad Cities
Issue date:	11/01/1979
From:	Kopacz J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19210C672	List: ML19210C671 ML19210C684
References
LER-79-033-01T, LER-79-33-1T, NUDOCS 7911190425
Download: ML19210C684 (2)

Text

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3M 60 L @l6101 5101010 OOCK ET NUMBER l 2 l 5 l 6d4 l@l 69 1 ist012101719 ENT O ATE 74 l@l 11RE*IlORT 75 0lDATE Il 7191@ 83 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES o 2 l While evaluating piping restraints in accordance with NRC IE Bulletin 79-02, i O 3 l Standby Gas Treatment Systems A and B were declared inoperable at 11: 30 a.m. on l o 4 October 20, 1979 Analyses indicated that piping restraint 1/2-7509-R149 had a l o 5 safety factor of less than 2. The Standby Gas Treatment Systems were at all times l 0 e j functional and the requirements of Technical Specification 3.7.B.I.b were met. [

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40 42 43 44 47 CAUSE DESCRIPTICN AND COPRECTIVE ACTIONS h i o!l Evaluation of the design of restraint 1/2-7509-R149 found the design safety factors ]

[i li ; to be less conservative than originally analyzed. The restraint was modified to a I

, , j safety factor of greater than 4, and at 4:56 a.m. , October 21, 1979, the Standby Gas l l

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309-654-2241, Ext. 178  :

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1. LER NUMBER: LER/RO-79-31/01T-0 ll. LICENSEE NAME: Commonwealth Edison Company .

Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

While reevaluating restraint safety factors in accordance with NRC IE Bulletin 79-02, 1/2-7509-R149 was found to have a safety factor of less than 2. Analyzing the system stress with this restraint deleted, the ultimate stress on the system was found to be greater than 1/2. -

At this time, 11:30 a.m. , October 20, 1979, the "A" and "B" Standby Gas Treatment (SBGT) systems were declared inoperable and the con-ditions of Technical Specification 3 7.B.1.b were placed into effect.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The Standby Gas Treatment systems were mechanically sound at the time of this occurrence, and all piping and equipment were fully functional.

Also, primary aid secondary containments were fully operable and in effect. Safe plant operation was not compromised by this occurrence.

Vll. CAUSE:

An evaluation of the design of restraint 1/2-7509-R149, in accordance with NRC IE Bulletin 79-02, found the design safety factors to be less conservative than originally analyzed.

Vill. CORRECTIVE ACTION:

The restraint was modified to a safety factor of greater than 4, and at 4:56 a.m., October 21, 1979, the SBGT systems were declared oper-able.

1354 346 o