PNO-I-87-010, on 870211,reactor Scrammed from Full Power During Transient Initiated by Loss of Instrument Bus.Safety Injection Signal Received on High Steam Flow Coincident W/Low Steam Line Pressure.Plant Stabilized in Hot Shutdown

PNO-I-87-010:on 870211,reactor Scrammed from Full Power During Transient Initiated by Loss of Instrument Bus.Safety Injection Signal Received on High Steam Flow Coincident W/Low Steam Line Pressure.Plant Stabilized in Hot Shutdown

ML20210U661
Person / Time
Site:	Indian Point
Issue date:	02/12/1987
From:	Linville J, Meyer G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-87-010, PNO-I-87-10, NUDOCS 8702180540
Download: ML20210U661 (3)

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DCS No: 50286870211 Data: February - 12, 1987 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-87-10 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without varification or evaluation, and is basically all that is known by the Region I staff on this date. .

Facility: New York Power Authority Licensee Emergency Classification:

Indian Point Unit 3 Notification of Unusual Event Buchanan,.New York Alert DN 50-286 Site Area Emergency General Emergency

_X__ Not Applicable

Subject:

REACTOR SCRAM AND ESF ACTUATIONS At 8:28 a.m. on February 11, 1987, the Indian Point Unit 3 (IP-3) reactor scrammed from full power during a transient initiated by the loss of an instrument bus. Specifi-cally, the #34125 Volt AC Instrument Bus was lost when the #34 inverter output breaker tripped. The loss of this bus resulted in the loss of one of the power range nuclear instrumentation channels, which caused a turbine runback. Approximately 45 seconds later, a reactor scram occurred on steam flow / feed flow mismatch coincident with low steam generator level. The steam flow / feed flow mismatch occurred because both main boiler feed pump speed controllers were lost with the loss of the #34 instrument bus and the feed pumps dropped to minimum speed. Almost simultaneously, a safety injection (SI) actuation signal was received on high steam flow coincident with low steam line pressure. All safety systems responded as expected. No water was actually injected, since the reactor coolant system pressure did not drop below 2000 psi. The plant was stabilized in hot shutdown.

The SI signal also initiated closure of the main steam. isolation valves (MSIVs). The subsequent pressure spike in the steam generators caused several of the steam generator safety valves to open. One of the safety valves failed to properly reseat once the pressure was relieved. However, no problems were experienced with controlling the rate of the reactor coolant system cooldown.

Published reports stated that workers observed flashing in the Primary Auxiliary Building (PAB) during the transient. Later evaluation determined the flashing to be caused by the startup of the fluorescent lighting when power to the lighting was reset.

The licensee is continuing to investigate the incident, and the formal post-trip review is in progress. The resident inspectors, along with regional specialists and a section chief, are monitoring the licensee's activities and plans for restarting the unit.

The licensee issued a press release on February 11.

The State of New York has been notified.

CONTACT: G. Meyer J. Linville i 488-1183 914-739-8565 l

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