PNO-IV-99-035A, on 990810,heater Drain Line Pipe Rupture Occurred.Caused by Flow Accelerated Corrosion in Conjunction with Moisture Impingement.Licensee Has Completed Replacement of Damage Heater Drain Piping & Conducted Insps of Piping

PNO-IV-99-035A:on 990810,heater Drain Line Pipe Rupture Occurred.Caused by Flow Accelerated Corrosion in Conjunction with Moisture Impingement.Licensee Has Completed Replacement of Damage Heater Drain Piping & Conducted Insps of Piping

ML20210U165
Person / Time
Site:	Callaway
Issue date:	08/18/1999
From:	Graves D, Jim Melfi NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-99-035A, NUDOCS 9908200022
Download: ML20210U165 (1)

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August 18,1999 l

RRELilWINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-99-035A This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.

Facility Licensee Emeraency Classification Union Electric Co. Notification of Unusual Event I Callaway 1 Alert I Fulton, Missouri Site Area Emergency Dockets: 50-483 General Emergency

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1 X Not Applicable

Subject:

PLANT SHUTDOWN FOR GREATER THAN 72 HOURS DUE TO HEATER DRAIN LINE BREAK - UPDATE The licensee has completed their review and assessment of the heater drain line pipe rupture that occurred on August 10 and determined the cause to be flow accelerated corrosion in conjunction with eaoisture impingement. This resulted in higher than expected erosion rates along a straight section of 6-inch pipe (previously reported to be 8-inch) immediately downstream of a 45 degree elbow.

The licensee has completed replacement of the damaged heater drain piping. The licensee has also conducted inspections of other piping which had been considered to oe potentially susceptible to the same failure mechanisms which contributed to this event. No anomalous indications were identified. Structural and electrical system walkdowns in the area of the pipe ;

break were completed and no significant collateral damage was identified.

A special inspection team composed of NRC regional and headquarters personnel arrived onsite on August 14 to review the event and the licensee's subsequent corrective actions.

Included in the inspection scope was the development of a sequence of events associated with the break, and a review of the licensee's corrosion monitoring program. No issues were identified which would preclude a retum to power operations.

On August 17, the licensee performed a reactor startup with the reactor going critical at 9:33 p.m. (CDT). The licensee is currently conducting secondary plant startup in preparation i for synchronization with the grid and power ascension. The resident inspectors are presently monitoring the licensee's startup efforts.

Region IV has informed the office of the Executive Director for Operations, the Office of Nuclear Reactor Regulation, and the Office of Public Affairs. The state of Missouri will be informed. l This information has been discussed with the licensee and is current as of 8:30 a.m. on August 18,1999. )

Contact:

DAVID GRAVES JIM MELFi ('

(817)860-8141 (573)676-3181 1 9908200022 990818 i '

PDR IbE '

PNO-IV-99-035A PDR t , . -

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