ML13016A503

Lr - NRC-FENOC Telecon Notes Shield Building Draft RAIs -- 2012-12-18

ML13016A503
Person / Time
Site:	Davis Besse
Issue date:	12/20/2012
From:	- No Known Affiliation
To:	Division of License Renewal
References
Download: ML13016A503 (4)

Text

Davis-BesseNPEm Resource From: dorts@firstenergycorp.com Sent: Thursday, December 20, 2012 10:55 AM To: CuadradoDeJesus, Samuel Cc: custerc@firstenergycorp.com

Subject:

NRC-FENOC Telecon Notes re: Shield Building Draft RAIs -- 2012-12-18 Attachments: NRC telecon 20121218 DRAIs Shield Bldg.pdf Sam, attached are the FENOC notes from the telephone conference call held on December 18, 2012, related to the draft requests for additional information on the Shield Building.

Please contact me with questions regarding the attached notes.

Thank you, Steve Dort Davis-Besse License Renewal

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Hearing Identifier: Davis_BesseLicenseRenewal_Saf_NonPublic Email Number: 3996 Mail Envelope Properties (OF13F07833.9A3A2669-ON85257ADA.0056EEE2-85257ADA.00576958)

Subject:

NRC-FENOC Telecon Notes re: Shield Building Draft RAIs -- 2012-12-18 Sent Date: 12/20/2012 10:54:45 AM Received Date: 12/20/2012 10:55:18 AM From: dorts@firstenergycorp.com Created By: dorts@firstenergycorp.com Recipients:

"custerc@firstenergycorp.com" <custerc@firstenergycorp.com>

Tracking Status: None "CuadradoDeJesus, Samuel" <Samuel.CuadradoDeJesus@nrc.gov>

Tracking Status: None Post Office: FirstEnergyCorp.com Files Size Date & Time MESSAGE 895 12/20/2012 10:55:18 AM NRC telecon 20121218 DRAIs Shield Bldg.pdf 25449 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Doc No. 121812 TO: File DATE: December 18, 2012 FROM: Steven Dort

SUBJECT:

NRC Telecon Regarding Davis-Besse License Renewal -

Shield Building Draft Requests for Additional Information NRC Attendees: Sam Cuadrado de Jesús, Bryce Lehman, Abdul Sheikh FENOC Attendees: Cliff Custer, Steven Dort, Allen McAllister, Jon Hook, Thomas Henry, Gerald Wolf This telephone conference call (telecon) was initiated by Sam Cuadrado de Jesús, NRC Project Manager for Davis-Besse License Renewal. The telecon took place at 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> on December 18, 2012. The purpose of the call was to discuss NRC draft follow-up requests for additional information (RAIs) B.2.43-2 and B.2.43-3 regarding the Davis-Besse Shield Building Monitoring Program, as follows:

Follow-up DRAI B.2.43-2 This draft RAI questions the sample size for future inspections of Shield Building core bores, and the technical basis for the adequacy of the sample size. Specifically, NRC Staff requests a summary of the testing performed and the results of the testing. The use of impulse response testing methods instead of inspections of core bores was discussed, and it was stated that inspection of core bores is more accurate than the results from continued impulse response testing. NRC Staff questioned why inspection of 20 core bores is acceptable going forward. FENOC stated that the Shield Building Root Cause Evaluation is clear, that the cause was a discrete event that required specific environmental and design conditions to be present for the event to have occurred, and that there is no aging effect associated with the cracking in the Shield Building. Based on this conclusion, the number of samples is not important. Rather, the inspections are being performed by FENOC to confirm the Root Cause conclusion by showing that there are no changes in the nature of the internal cracks over time.

FENOC and NRC Staff also discussed the [in-progress] evaluation of the Shield Building licensing basis. FENOC stated that the licensing basis evaluation should be complete in July 2013.

Follow-up DRAI B.2.43-3 This draft RAI questions why testing for internal cracking using core bores was not performed on the other structures within the scope of license renewal, and whether structural coatings for the other structures are included in the scope of license renewal. FENOC reiterated that four specific environmental and design conditions must be present to generate the forces necessary to cause internal cracking in concrete structures as was observed in the Shield Building; none of the other structures within the scope of license

2 renewal meet the structural design conditions (i.e., the design associated with the flute shoulders on the Shield Building) necessary for internal laminar cracking to have occurred during the blizzard of 1978. However, based on a recommendation from NRC Region III Inspector Mel Holmberg that examining a core bore from another site structure would bolster the Shield Building Root Cause Evaluation, FENOC examined a core bore in the Auxiliary Building.

The Auxiliary Building and resulting core bore location were chosen based on similarities of reinforcing bar density, wall thickness, and a southwest location (the direction from which the blizzard approached in 1978). The core bore inspection performed in the Auxiliary Building showed that cracking did not occur in a building without the flute shoulder configuration of the Shield Building.

NRC Staff asked why cracking occurred in the main steam line area of the Shield Building, since it isnt close to the flute shoulders. FENOC responded that the reinforcing bar density (i.e., high density) in the area of the main steam lines is the same as that in the top of the Shield Building, and the steam line reinforcing bar is connected to adjacent flute shoulders, so the cracking propagated into the main steam line area from cracking that initiated in the flute shoulders.

NRC Staff stated that FENOC should consider performing a core bore inspection on another uncoated structure to further support the conclusions of the Root Cause. FENOC responded that the conclusions are already confirmed by core bore inspections of the uncoated barrel sections of the Shield Building between the flute shoulders. No internal laminar cracking initiated in the barrel sections of the Shield Building; cracking initiated in the flute shoulder regions and propagated from there to other sections of the Shield Building.

NRC stated that they will issue the RAIs. There was no further discussion, and the call was concluded.