ML11136A055

OL - Draft Request for Additional Information Regarding GL 2004-02 Round 2

ML11136A055
Person / Time
Site:	Watts Bar
Issue date:	04/18/2011
From:	Office of Nuclear Reactor Regulation
To:	Division of Operating Reactor Licensing
References
Download: ML11136A055 (3)

Text

WBN2Public Resource From: Poole, Justin Sent: Monday, April 18, 2011 3:52 PM To: Crouch, William D Cc: WBN2HearingFile Resource

Subject:

Draft Request for Additional Information regarding GL 2004-02 Round 2

Bill, Below, for your review, are preliminary Request for Additional Information (RAI) questions regarding Watts Bar Nuclear Plant (WBN), Unit 2. Please review to ensure that the RAI questions are understandable, the regulatory basis is clear, there is no proprietary information contained in the RAI, and to determine if the information was previously docketed. Please also let me know how much time Tennessee Valley Authority (TVA) needs to respond to the RAI questions.

Justin C. Poole Project Manager NRR/DORL/LPWB U.S. Nuclear Regulatory Commission (301)4152048 email: Justin.Poole@nrc.gov

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EMCB RAI 1 In response to Item 3.k.1 of the Watts Bar Nuclear Plant (WBN), Unit 2, supplemental Generic Letter (GL) 2004-02 response (Reference 1), four out of the six load combinations for which the strainers were structurally qualified include loads due to either an operating basis earthquake (OBE) or a safe shutdown earthquake (SSE). However, no information was provided regarding the structural damping values used in the seismic analyses of the strainers, including their individual components, as part of the structural qualification of these components. Please provide the OBE and SSE damping values used for the strainer structures in the aforementioned analyses.

EMCB RAI 2 Note 3 accompanying the loading combinations in Reference 1, which were considered in the structural analyses of the WBN Unit 2 sump strainers, indicates that loads due to jet impingement and debris impact were not considered in the final strainer design. The response to Item 3.k.3 of the WBN Unit 2 supplemental GL 2004-02 response clearly articulates that loads due to jet impingement are not credible, due to the location of the sump strainers. However, there is little justification for neglecting the postulated loads due to debris impact. Please provide additional justification and/or explanation regarding the exclusion of debris impact loads from the applicable loading combinations considered in response to Item 3.k.1.

EMCB RAI 3 Note 6 accompanying the aforementioned loading combinations considered in the structural analyses of the WBN Unit 2 sump strainers, indicates that loads due to hydrostatic or hydrodynamic effects were not considered in the final strainer design. There is no accompanying justification for the exclusion of the effects of these loads in the sump strainer structural analyses. Please provide additional justification regarding the exclusion of hydrostatic and hydrodynamic loads. This justification should include, but not be limited to, whether submergence, sump strainer construction, or the bounding of these effects by other loads account for the absence of hydrostatic and hydrodynamic loads in the current structural analyses.

1

2 Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 346 Mail Envelope Properties (19D990B45D535548840D1118C451C74D7F6E4FCEB4)

Subject:

Draft Request for Additional Information regarding GL 2004-02 Round 2 Sent Date: 4/18/2011 3:51:41 PM Received Date: 4/18/2011 3:51:43 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 2907 4/18/2011 3:51:43 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: