ML051460262

E-mail Emailing: PNO-1-05-17 MS3 Alert - Low SG Press Si.Wpd

ML051460262
Person / Time
Site:	Millstone
Issue date:	04/18/2005
From:	Keith Heater Division Reactor Projects I
To:	Barber S, Bores R, Paul Krohn, O'Daniell C, Sieller N NRC Region 1
References
FOIA/PA-2005-0207, PNO-1-05-17
Download: ML051460262 (4)

Text

From: Keith Heater To: Barber, Scott; Bores, Robert; Krohn, Paul; O'Daniell, Cynthia; Sieller, Nicole Date: 4/18/05 3:42PM

Subject:

Ernailing: PNO-1-05-17 MS3 Alert - Low SG Press SI.wpd To ALL, The attached document is a PNO-1-05-17 reference Millstone Station, Unit 3.

Item references a MSSV not reseating after an Si actuation on low main steam line pressure.

ADAMS #: ML051080484 Point of Contact is: Mr. Paul G. Krohn @ 610-337-5120 vr, Keith A. Heater NRC Region-I, DRP Administrative Support Team Branches 3,6 & 7 610-337-5226 "The hardest thing in the world to understand is the income tax."

- Albert Einstein q

DCS No.: 05000423041705 Date: April 18, 2005 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-1-05-17 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 the Region I staff on this date.

Facility Millstone Unit 3 Power Station Licensee Emergency Classification Waterford, CT Notification of Unusual Event Docket: 50-423 X Alert Site Area Emergency General Emergency Not Applicable

SUBJECT:

ALERT DECLARED AT MILLSTONE 3 DUE TO A MAIN STEAM SAFETY VALVE NOT RESEATING AFTER AN SI ACTUATION ON LOW MAIN STEAM LINE PRESSURE On April 17, 2005, at 8:29 a.m. Millstone Unit 3 experienced a reactor trip from full power. In addition to the reactor trip, one of two trains of the Safety Injection (SI) and Main Steam Isolation (MSI) subsystems actuated. Control room operators manually initiated a full SI and MSI. There were also indications that multiple main steam line safety valves (MSSVs) opened with at least one MSSV that appeared to remain open. As a result, at 8:42 a.m., Dominion Nuclear Connecticut (DNC) declared an Alert due the failure of one MSSV to close. The response of the MSSVs is under further review.

The SI and MSI signals were initially attributed to a sensed low steam line pressure on one of four steam generators. Auxiliary Feedwater (AFW) automatically actuated during the event.

However, the turbine-driven AFW pump initially tripped and was successfully reset locally and restarted. Both motor-driven AFW pumps operated as expected to maintain steam generator levels. Due to the additional inventory added during the SI, the pressurizer filled and an overpressure condition caused pressurizer valves to lift and reseat. Operators responded to these conditions, stabilized the plant in Hot Standby and began a cooldown. Subsequently, the plant entered hot shutdown at 7:03 p.m. and DNC terminated the Alert at 7:05 p.m. The facts of this PN were verified with the Site Vice President - Millstone.

NRC resident inspectors responded to site, the NRC entered "monitoring" mode at 9:53 a.m.,

and activated the RI incident response center. The NRC, including on-site inspectors, monitored DNC's activities to stabilize the plant throughout the event including actions to place the plant in a hot shutdown condition.

DNC has established an event review team to review the root causes, extent of condition, and actions taken to address the event. The NRC staff is assessing event follow up per NRC Management Directive 8.3. Additional NRC inspection is planned to review DNC's actions including their root cause determination, safety system response including any identified equipment issues, and actions taken to mitigate the consequences of the event.

The Region I Public Affairs Office issued a press release and has responded to media inquiries.

DNC issued three press releases during the event. The States of Connecticut and New York have been informed.

ADAMS Accession Number: ML051080484 CONTACT: Paul Krohn (610) 337-5120

-DN DISTRIBUTION: (PN Recipient List)

OWFN TWFN LST Chairman Diaz IRO PDR Comm. Lyons NMSS Comm. Jazcko ACRS Comm. McGaffigan Jr. OIG Comm. Merrifield RES OlP NSIR OCA OGC OPA EDO OE NRR SECY Regional Offices By Fax:

DOT:Trans INPO NSAC RI Resident Office Licensee:

ADAMS Accession Number: ML051080484 SISP Review Complete: PGK (Reviewer's Initials)

DOCUMENT NAME: P:\Region 1\Millstone 3 4_17_05 Event\MS3 PN\PNO-1-05-17 MS3 Alert

- Low SG Press SI.wpd After declaring this document UAn Official Agency Record" it will be released to the Public.

To receive a copy of this document, indicate in the box: 'C' = Copy without attachment/enclosure "E =Copy with attachment/enclosure N" = No copy OFFICE RI/DRP RI/DRP RIORA L RI/DRP I RI/DRPI NAME SBarber/GSB RBores/RJ H)Screnci/DP,4RPKrohn/PGK ABlough/ARD

,,DATE 04/18/05 04/18/05 04/18/05 104/18/05 104/18/05 .

OFFICIAL RECORD COPY Region I Form 83 (Rev. July 2, 2003)