ML11136A088

OL - Need for Clarification

ML11136A088
Person / Time
Site:	Watts Bar
Issue date:	04/19/2011
From:	Office of Nuclear Reactor Regulation
To:	Division of Operating Reactor Licensing
References
Download: ML11136A088 (2)

Text

WBN2Public Resource From: Poole, Justin Sent: Tuesday, April 19, 2011 3:21 PM To: Crouch, William D Cc: WBN2HearingFile Resource

Subject:

Need for clarification Below are 2 questions that came up during the ACRS meeting on February 11, 2011. They were reiterated during our meeting on March 11, 2011, that clarification was needed from TVA to address these items. Please see the questions below.

The final need for clarification was not a result from the ACRS meeting but was brought up during the March 11, 2011 meeting.

Justin C. Poole Project Manager NRR/DORL/LPWB U.S. Nuclear Regulatory Commission (301)4152048 email: Justin.Poole@nrc.gov Here are the questions from electrical ACRS presentation:

1. Section 8.4.2 of the SER titled Station Blackout Coping Duration, documents details on AC independent coping methodology adopted for Watts Bar Unit 2. Section 8.4.2.4 of the report discusses effects of loss of ventilation and identifies room temperatures with critical operating equipment. The staff needs additional information on the electrical components located in dominant areas of concern and methods used to provide assurance on operability of the components at high ambient temperatures.

2. Section 8.3.1 discusses the onsite AC power sources and compliance with GDC 17. Section 8.3.3.1.1 provides details on submerged electrical equipment as a result of a loss of coolant accident. The licensee has stated that the electrical equipment required to function during LOCA is not degraded due to association with submerged equipment as it is adequately protected. The staff needs additional information on equipment that is submerged and not needed and powered from the common power source with essential equipment. The licensee should identify the methodology used to evaluate operability of essential equipment. In addition, the consequences of multiple high impedance faults simultaneously developing on submerged equipment should be discussed in detail. Excerpts from calculations demonstrating operability of equipment should be included in the response.

March 11, 2011 meeting:

During the public meeting, the licensee discussed the electrical open items. Specifically open item 27 (appendix HH) related to design margin associated with common station service transformers (CSST A, B, C &

D) needed clarification. The staff is requesting clarification on adequacy in sizing and voltage drop on the class 1E busses when an abnormal operating occurrence results in trip of both units.

1

Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 353 Mail Envelope Properties (19D990B45D535548840D1118C451C74D7F86CC555E)

Subject:

Need for clarification Sent Date: 4/19/2011 3:20:49 PM Received Date: 4/19/2011 3:20:51 PM From: Poole, Justin Created By: Justin.Poole@nrc.gov Recipients:

"WBN2HearingFile Resource" <WBN2HearingFile.Resource@nrc.gov>

Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 2444 4/19/2011 3:20:51 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

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