ML11258A101

E-mail from T. Chan, Entergy, Subj: Unit 3 480V Switchgear Flood Protection

ML11258A101
Person / Time
Site:	Indian Point
Issue date:	01/13/2011
From:	Chan T Entergy Nuclear Operations
To:	Halter M NRC Region 1
References
FOIA/PA-2011-0272
Download: ML11258A101 (3)

Text

Halter, Mandy From: Chan, Tat Sent: Thursday, January 13,2011 8:41 AM To: Halter, Mandy Cc: Anderson, Harry R; Burroni, Richard J

Subject:

RE: Unit 3 480V Switchgear Flood Protection

Mandy, The system interaction study was performed underthe Project Identification PASN IP-3 SIS. Copy of the cover sheet is attached below. Please let me.know ii Ihcan be of further assistance.

Tat

From: Halter,. Mandy Sent: Thursday, January 13, 2011 6:58 AM To:,Chan, Tat

Subject:

RE: Unit 3 480V Switchgear Flood Protection Hi Tat, Can you please provide the document ID number, revision number (or date of document, if appropriate), and complete title name of the system interaction study that you referenced below? I will use this information for documentation purposes in our quarterly inspection report.

Thanks and kind regards, Mandy From: Chan, Tat Sent: Monday, December 20, 2010 9:27 AM To: Halter, Mandy;, Cataldo, Paul C Cc: Anderson, Harry R; Walpole, Robert W; Conroy, Patric W; Burroni, Richard 3; Prussman, Stephen G

Subject:

Unit 3 480V Switchgear Flood Protection Mandy / Paul, Information regarding Unit.3 480V Switchgear Flood Protection. The analysis between Unit 2 & Unit 3 is slightly different in addressing this issue. For Unit 3, the study is done as part of the Chapter 6 of the System Interaction Study. See attached excerpts and the relevant sections of the FSAR are Chapters,9.6.2.9, 10.2.4 and 1.6.1.3. Basically, the concern for flooding at Unit 3 480V Switchgear stem from a postulate failure of the Seismic III circulating water pump,/ piping. Mitigation strategy involves installation of a 4 barrier at the entrance of the cell from the turbine hall and level switches in the piping tunnel. See excerpts of Chapter 16.1.3 below. Please let me know if I can be of further assistance.

<< File: Unit 3 Flooding System lnteraction.pdf >>

Tat Excerpts of FSAR Chapter 16.1.3

1.

-hil ý1.I ý No safety related equipment is located in the Turbine Hall. However, fooding fron, the Turbine Hail cou*d potentially affect the performance of the 480 volt switchgear located in the Control Building at Elevation '45' only if the water reached theelevation of ' 5'6-. Since the Circulatng Water System is an open system having absolutely no valves, and therefore no means .f producing a high dynamic head, the probalbility of a failure is practically zero. Howiever, to 4assure that the 480 volt switchgear would not be adversely affected by flooding, redundant levee alarm switches were installed in the pipe tunnel at Ele.;ation 3'3" of the.Turbine Hall. These switches sense high -,vater in the pipe tunnel and give an indication to the Cbntrol Room. In addiion, a barrme was installed at the doorway to the s,itchgear room to provide protection from flooding up to 19'. The operators have ample time to. investigate any flooding problem and take appropriate action by shutting down the circulating pumps to prevent flooding to Ele vation 19'.

A DBE seismically induced break of the Turbine Hal( Elevation 15'-0" fire protection header could result in flooding of the 480 volt switchgear with a potential loss of -all four 4830 vott emergency buses. Modification 93-3-433 FRW added six seism-c Safety?]*e*t supports so that the portion of the Aumnted 'Quality Relate**piping and deluge 'alves for the water spray systems for Main, Station, Auxiliary, and Unit Auxiliary Transformners, located in the Control Building, vill be capable of withstanding a Design Basis seismic event.

Inadvertent actuation tf the Fire Protection System in the electricat tunnels will not potenafly affect the performance of safety-related equipment in the Control Building. The electrcal tunnels are provided with floor drains to handle water from the cable tray fire protection spray system.

These.drains discharge to grade outside the tunnel