ML12213A380

E-Mail from E. Sanchez-Santiago, Riii, to M. Murphy, Nro/Dorl, Et. Al., Subject: FW: Davis Besse Shield Building Technical Review Discussion Items

ML12213A380
Person / Time
Site:	Davis Besse
Issue date:	11/16/2011
From:	Sanchez-Santiago E NRC/RGN-III
To:	Jamnes Cameron, Timothy Lupold, Murphy M Office of Nuclear Reactor Regulation, NRC/RGN-III, Office of New Reactors
References
FOIA/PA-2012-0121
Download: ML12213A380 (2)

Text

Graves, Herman From: Sent: To: Cc:

Subject:

Attachments:

Sanchez Santiago, Elba Wednesday, November 16, 2011 7:38 AM Murphy, Martin; Lupold, Timothy; Cameron, Jamnes; Wilson, Adam; Kimble, Daniel;Rutkowski, John; Hills, David; Rezai, Ali; Gonzalez, Hipolito; Thorp, John; Haskell, Russell;Nolan, Ryan; Mahoney, Michael; Hernandez, Pete; Mitlyng, Viktoria; Chandrathil, Prema;Neurauter, James; Cardona-Morales, Pedro; Briley, Thomas; CuadradoDeJesus, Samuel;Zimmerman, Jacob; Thomas, George; Hoang, Dan; Logaras, Harral; Barker, Allan; Auluck, Rajender; Sheikh, Abdul; Lehman, Bryce; Morey, Dennis; Snyder, Amy; Wiebe, Joel; Bozga, John; Meghani, Vijay; Stone, AnnMarie; Smagacz, Phillip; Davis-BesseHearingFile Resource;Riley (OCA), Timothy; Jessup, William; Graves, Herman; Pires, Jose; Hogan, Rosemary;Case, Michael; Richards, Stuart; Manoly, Kamal; Orth, Steven Hiland, Patrick; Shear, Gary; OBrien, Kenneth; West, Steven; Reynolds, Steven FW: Davis Besse Shield Building:

Technical Review Discussion Items 11-15-2011 briefing with licensee.docx Good Morning, Attached is a summary of the discussion Jim had with the licensee yesterday.

Feel free to contact me if you have any questions.

Thanks, Elba From: Neurauter, James Sent: Tuesday, November 15, 2011 6:26 PM To: Sanchez Santiago, Elba Cc: Hills, David; Kimble, Daniel; Meghani, Vijay

Subject:

Davis Besse Shield Building:

Technical Review Discussion Items Elba Pass on to technical reviewers.

Thanks Jim 1 Davis-Besse Shield Building Laminar Cracking Licensee had extended discussions today with Professor Darwin.Professor Darwin could not support an analytical determination of rebar splice strength in presence of a laminar crack. Basically, the licensee needs to identify sufficient uncracked zones at top of shield building so bond at rebar splices can be credited as effective.

Licensee plan going forward [1900 on 11/15/2011]:

• Lower portion of shield building -vertical rebar controls -seismic" Upper portion of shield building -circumferential rebar controls -thermal loads* Perform additional IR / core bore mapping at top of shield building to identify uncracked concrete areas* Demonstrate effective circumferential rebar is adequate for design loads. This will be somewhat subjective since actual splice locations are not known and licensee has indicated rebar mapping is ineffective." New design basis calculations:

o At bottom: make sensitivity calculation that removed rebar in shoulder regions a design basis calculation o At top: based on IR / core bore mapping, show that circumferential rebar connectivity is sufficient to demonstrate adequate load capacity for design loads NRC technical reviewer challenges: " Is licensee's proposed success path a viable solution" How to define good concrete areas* What portion of the shield building requires good concrete for sufficient bond strength at splices o Portion of splice in crack zone vs installed splice overlap length o Even though rebar splices are staggered, basis to credit load transfer of failed splice to adjacent rebar NRC reviewers need to come to a consensus:

is licensee's proposed success path a viable solution to identified circumferential cracking