PNO-II-93-007, on 930204,plant Commenced Power Reduction Due to Identified Steam Leakage on 1B1 MSR High Pressure Operating Vent Line.Resident Inspectors Have Been Following Licensee Actions.State of Tn Not Required to Be Informed

PNO-II-93-007:on 930204,plant Commenced Power Reduction Due to Identified Steam Leakage on 1B1 MSR High Pressure Operating Vent Line.Resident Inspectors Have Been Following Licensee Actions.State of Tn Not Required to Be Informed

ML20203G168
Person / Time
Site:	Sequoyah
Issue date:	02/04/1993
From:	Kellogg P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
References
PNO-II-93-007, PNO-II-93-7, NUDOCS 9712180067
Download: ML20203G168 (2)

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a, j)MMI h lY February 4, 1993

8RELIMIMARY. NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PHO-II-93-007 1his 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 the Region II staff on this date.

IsollitY kicensee Emercency classification Tennessee Valley Authority Notification of Unusual Event Sequoyah 1 Alert Soddy-Daisy, Tennessee Site Area Emergency Dockets: 50-327 General Emergency X Not Applicable

Subject:

POWER REDUCTION / FORCED OUTAGE GREATER THAT 72 HOURS DUE TO LEAK ON 1B1 MSR HIGH PRESSURE OPERATING VENT LINE.

On Febitary 4, 1993 at approximately 2:00 pm, Sequoyah, Unit 1 commenced a power reduction due to identified steam leakage on the 1B1 MSR high pressure operating vent line. The leak was not isolable from the high pressure turbine extraction steam line and efforts to effect a repair at full power were not attempted due to the steam hazard. The leak was identified at a piping location whicd"had been temporarily repaired

,turing past operation and was not isolable from main turbine extraction iteam. The licensee believes that the leak was caused by erosion of the [.',

piping at a location where they have seen similar piping failures on r other components during past operating cycles. Licensee management '$P,~; t, decided to place Unit 1 in MODE 3, break condenser vacuum, and make a permanent repair at this time. Steam leakage in the turbine building had not effected any safety systems.

As of 4:00 pm on February 4, 1993, Unit 1 was at approximately 90 percent power with unit shutdown continuing and preparations being made to establish conditions to commence work. The forced outage is expected to take approximately 3 days.

Unit 2 operated at approximately full power throughout the event and was not affected.

Regional action: Resident inspectors have been following licensee's actions. A region based inspector is on site reviewine the licensee's

. erosion / corrosion program and will monitor selected licensee activities during the forced outage.

The licensee will make notification to local media with regard to Unit i shutdown and outage related work.

The State of Tennessee was not required to be informed, nor were they informed by the licensee of the forced outage.

C/R DISTRIBUTION:

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