05000334/LER-1981-091, Updated LER 81-091/01X-1:on 811029,break in Redundant Underground 12-inch Supply Header Resulted in Loss of Fire Water Sys.Caused by External Finger Corrosion Along Pipe Bottom.Total Sys Piping change-out Not Warranted

Updated LER 81-091/01X-1:on 811029,break in Redundant Underground 12-inch Supply Header Resulted in Loss of Fire Water Sys.Caused by External Finger Corrosion Along Pipe Bottom.Total Sys Piping change-out Not Warranted

ML20069K331
Person / Time
Site:	Beaver Valley
Issue date:	10/11/1982
From:	DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20069K322	List: 05000334/LER-1981-091, Forwards Updated LER 81-091/01X-1
References
LER-81-091-01X, LER-81-91-1X, NUDOCS 8210260167
Download: ML20069K331 (2)

LER-2081-091, Updated LER 81-091/01X-1:on 811029,break in Redundant Underground 12-inch Supply Header Resulted in Loss of Fire Water Sys.Caused by External Finger Corrosion Along Pipe Bottom.Total Sys Piping change-out Not Warranted

Event date:
Report date:
3342081091R00 - NRC Website

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68 74 75 REPORT DATE 80 8 60 61 OOCKET NUMBER EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 3121l On 10/29/81 at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br /> , a break in a redundan t underground 12 inch supp1v header l 3 lal I resulted in the temporary loss.of the fire water system (Tech. Spec 3.7.14.1) . l 314 I l Tr public health and safety wasn't affected since backup fire protection uas l 0l3l l avai?able, the system was returned to service in approximately one hour and fire l 0 l6 l l Patches were established during the time required to identify which of the ad- l ol7ll 'ac nt supply headers was broken. This is the third failure of this type. l l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1 loll The ruptired section was renlaced and returned to service on 11/1/81. Broken l

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. IE Attachment to LER 81-91/01X-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 On 10/29/81 at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, a fire line break, in a redundant underground 12 inch supply header between fire system valves [FP-5] and [FP-11], resulted in the temporary loss of the Fire Protection Water System.

From the results of an analysis of the broken pipe section, performed by the Industrial Testing Laboratory (ITL), it was concluded that the break had occurred from a slight bending moment being applied to the pipe, in an area that was greatly weakened by external finger corrosion. The moment required for fracture was much less than expected to fracture the pipe due to the corrosion present. The corrosion was apparently not stress corrosion because cracking was not the forn,. nor was it from an electrolytic mechanism. The bituminous coating was breached in 'hpots" on the pipe bottom and was almost continuolusly missing from the top and grades in between. It was concluded that the origin of the corrosion must have originated in the pipe bedding material.

Subsequent to this incident, on 9/8/82 another segment of the fire line failed. Pipe segments were sent to ITL for analysis. Their conclusions to the mode of failure paralleled initial engineering observations that crack initiation at the break site resulted from over torquing of retainer flange setscrews upon initial installation of the line. Crack growth then continued due to bedding erosion caused by leakage from the crack and that this bedding erosion coupled with an already induced crack resulted in the complete failure. External finger corrosion which had greatly reduced the pipe wall thickness causing the incident which led to this LER was not evident. Because no connection was drawn between these most recent pipe failures, the station does not feel that a total piping replacen.ent of the cast iron fire line is warranted at this time.