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: Sanchez Santiago, Elba Sent: Wednesday, November 16, 2011 7:38 AM To: 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 Cc: Hiland, Patrick; Shear, Gary; OBrien, Kenneth; West, Steven; Reynolds, Steven

Subject:

FW: Davis Besse Shield Building: Technical Review Discussion Items Attachments: 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