ML20128H973

Discusses Investigation of 900320 Event at Facility, Involving Loss of Offsite Power & Failure of Onsite Power on Demand

ML20128H973
Person / Time
Site:	Vogtle
Issue date:	03/22/1990
From:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Carr, Roberts, The Chairman NRC COMMISSION (OCM)
Shared Package
ML20128H951	List: IA-92-330, Forwards List of NRC Employees Who Will Visit Facility on 900322-30.Requests Unescorted Access to Vital & Protected Areas for Individuals Who Have Clearance ML20128H948 ML20128H963 ML20128H973 ML20128J060 ML20128J095
References
FOIA-92-330 NUDOCS 9302170257
Download: ML20128H973 (4)

Text

IT W, q'e - UNITED STATES

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m wm MEMORANDUM FOR: Chairman Carr Comissioner Roberts Comissioner Rogers Comissioner Curtiss ,

Li Comissioner Remick FROM: James M. Taylor Executive Director for Operations

SUBJECT:

INVESTIGATION OF MARCH 20, 1990 EVENT AT V0GTLE NUCLEAR POWER PLANT, INVOLVING LOSS OF OFFSITE POWER AND FAILURE OF ONSITE POWER ON DEMAND AT UNIT 1 On March 20,1990, at 9:58 a.m. EST, the licensee for the Vogtle Nuclear Power Plant notified the NRC they had declared a Site Area Emergency for Unit I due to a loss-of offsite power concurrent with a loss of onsite emergency diesel generator (EDG) capability. The loss of offsite power was caused by a truck accident in the switchyard. At the time of the incident Unit I was in cold .

shutdown with the B reserve auxiliary transformer and the B emergency diesel generator out of service for maintenance. The A EDG started as designed but-

__-( imediately tripped. Thirty-six minutes into the event, the A EDG was manually _

u-O started, at which time core cooling was reestablished to tinit 1. The Unit 1-  !

reactor coolant-temperature peaked at 136' F and stabilize 1-at 100 F-after emergency AC power was restored. The licensee downgraded the event-to an_ Alert L

at 10:15 a.m. EST based on the restoration of onsite power. Unit 2 reactor also tripped from 100 percent power as a result of the truck accident, _but did -

not lose offsite power. At 11:29 a.m. EST the-B reserve' auxiliary transformer was re-energized, restoring normal power to tne engineered safeguards buses.

An Augmented Inspection Team (AIT) was immediately sent-to the site by Region ~  :

1 II to investigate the event. However, because of the safety significance and the potential regulatory. questions the event raises, I have requested' AEOD.to take the necessary actions to upgrade the current AIT to a seven member NRC Incident Investintion Team (?IT). ,- Arrangements are being made under .the pro-visions of a Mem andum of Agreement with the Institute of- Nuclear Power Opera-tions for industry participation. The team is to:- (a) fact find as to what.

L; happened; (b) identify the' probable cause as to why it happened; and.(c) make.

appropriate findings and conclusions which would form the basis for any neces-

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sary follow-on actions. 9 The team will report directly to me and is comprised of: AlChaffee,(RV) Team: .

Leader;_ Warren Richard-Kendall,. Lyon,Garmon gnRR); (NRR);West, William Jones,-

Jr.,-(NRR); (AE0D);

and Eugene Trager, (AE00)-}.

William Lazarus-(RI Enclosed is the charter for the IIT to use in the review of the event.

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The Commissioners The team was selected on the bases of their knowledge and experience in-the fields of reactor systems, reactor operations, human factors, and power  ;

distribution systems. Team members have no direct involvement with Vogtle. The '

additional team members and the team leader'are currently enroute to the site.

lhe licentee has agreed to preserve the equipment in an "as-found" state until the licensee and the IIT have had an opportunity to evalu te the event. The licensee's actions have been confirmed ay the Regional Administrator in a Confirmatory Action Letter which was issued on March 23, 1990. The licensee has also agreed to maintain Vogtle Unit 1 in a shutdown condition until concurrence is received from the NRC to return to power.

The !!T report will constitute the single NRC fact-finding investigation report. It is expected that the team report will be issued within 45 days from n.nw.

s mes M. T ylor' Executive Director for Operations cc: SECY OGC ARCS

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ENCLOSURE t Incident Investigation Team Charter Loss of Onsite Power and Failure of Onsite Power on Demand at Vogtle Unit 1.

The scope of the llT investigation should include conditions preceding the event, event chronology, systems response, human f actors considerations, equipment performance, precursors to the event, emergency response (NRC, licensee, and Federal and State agencies), safety significance, radiological considerations, and whether the regulatory process and activities preceding the event contributed to it. Within the framework of this scope the IIT should specifically:

With respect to conditions preceding the event: Evaluate the activities and plans which established the initial plant conditions. Identify the initial plant conditions (prior to start of the transient). Identify whether the conditions were prudent and proper. Facts should be obtained regarding the licensee's actions associated with providing assurance of adequate RHR cooling during the outage activities, including planning and coordination of equipment outages, emergency responses to mid-loop operational events, and review of applicable NRC generic communications. Identify any procedural requirements and/or deficiencies associated with the fuel truck's movement in the protected area.

With respect to event chronology: Develop and validate a detailed sequence of events associated wi u the loss of all AC power transient on Unit 1. Establish I the cause of the Unit 2 trip.

With respect to emergency response: Develop and validate a detailed sequence of events associated with implementation of the Emergency Plan Implementing Procedures, including problems associated with_the ENN and ERF computer.

With respect to systems response: Evaluate the response of the '1A' Diesel Generator, including equipment performance (Blackout Sequencer and Jacket Water Pressure). Determine whether the Unit I switchyard breaker actuations were appropriate and expected.

With respect to human factors considerations: Evaluate personnel performance including local ooerator actions in response to the '1A' DG failure to start.

With respect to safety significance of the event: Evaluate the potential for long term core damage due to this transi,ent. . Include the responses of operations and maintenance personnel, RCS heatup, and potential containment challenges. Evaluate the potential for a truck fuel conflagration in this scenario and whether Fitness for Duty rule was complied with.

With respect to the regulatory process and activities proceeding the event:

Evaluate the-adequacy of plant Technical Specifications for safety system operability / availability during refueling mode and any implications to other modes.

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The scope of the investigation does not include:

Assessing violations of NRC rules and requirements; and Reviewing the design and licensing bases for the facility, except as necessary to assess the cause for the event under investigation.

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