ML12200A249

Presentation Slides on Shield Building /Containment Delamination

ML12200A249
Person / Time
Site:	Davis Besse, Crystal River
Issue date:	12/22/2011
From:	Bryce Lehman, James Neurauter, Rich D Division of License Renewal, Division Reactor Projects II, Division of Reactor Safety III
To:
References
FOIA/PA-2012-0121
Download: ML12200A249 (11)

Text

'2/23/2012 SHIELD BUILDING / CONTAINMENT DELAMINATION:

DAVIS-BESSE & CRYSTAL RIVER BRYCE LEHMAN - NRR/DLR JIM NEURAUTER - REGION III/DRS DANIEL RICH - REGION II/DRP 1

Agenda

" Davis-Besse Condition & Licensee's Position

" NRC's Position on Davis-Besse

" Impact on License Renewal

" Status Update on Crystal River o Impact on License Renewal

" Similarities & Differences Between Plants 1

~Yy

2/23/2012 Davis-Besse Shield Building

" Free-standing steel containment vessel surrounded by reinforced concrete shield building

" Shield Building Functions: A 13 Environmental & external missile protection for containment vessel 13 Biological shielding during normal operation and accident conditions I 13 Means for collection and filtration of fission product leakage following accident Initial Condition o Laminar crack identified in architectural flute shoulder area during hydro-demolition for replacement of reactor vessel closure head (October 1 Oth) o Crack found on the vertical side of the opening (left side, looking from the outside), generally along main reinforcing steel, and extends -6'across the top and "-4' across the bottom 2

2/23/2012 Construction Opening Flute/Shoulder Geometry 3

2/23/2012 Condition Assessment 7

• "Chipping back" along cracked [3 IR testing performed on 15 of 16 areas revealed crack extended flute shoulders beyond construction opening a Based on results, licensee assumed

• Impulse Response (IR) cracking throughout all shoulders methodology employed to investigate extent of crack o Core bores taken on 1 2 shoulders

• IR testing indicated crack to confirm crack boundaries extended -38' above construction opening c] Core bores inspected using boroscope to identify crack depths

• (4) core bores taken to validate IR results and widths 13 Indicated crack existed near outer 13 Very tight, less than 0.01" reinforcement mat Condition Assessment o IRtesting performed on 4 of 8 ii IR testing performed in 7 of 8 areas between flute shoulders flute areas io Two small regions adjacent to o Core bores taken from 6 of 8 Main Steam Line penetration flute areas blockouts are cracked

" IRtesting and core bores a3 Extent of cracking unique to penetrations confirmed laminar cracking not o Cracking regions exist at top 20' present in flute areas of Shield Building wall outside 13 One flute did have a vertical shoulder area crack, but determined to be o Spring line area appears to have isolated condition little or no cracking (top 5')

4

2/23/2012 Condition Assessment Summary

" Cracking is generic to all flute shoulder regions

" Cracks are confined to flute shoulder regions with exception of top 20' of Shield Building wall and two small regions near MSL penetrations o Cracking exists at top 20' of Shield Building wall outside shoulder region o Cracks are very tight, <0.01 ", and located near the outer reinforcing mat

'I Licensee's Position

" Believe sampling method of IR testing and core bores has characterized the extent of cracking in the structure o Primary concern is ability of outside rebar to perform its intended function. Observations of construction opening and testing indicate concrete is attached to rebar mat o Based on structural evaluation, cracking does not impact ability of structure to perform its intended safety functions

" Root cause is underway 5

2/23/2012 NRC's Position o NRC informed licensee it could restart (1 2/2) 13 Licensee developed a model with reasonable assumptions which demonstrated a reasonable expectation of operability 13 Staff continues to evaluate whether the shield building conforms to the design code requirements in the CLB

" This is currently being addressed by Region III in inspection space.

• The inspection is ongoing and the focus has shifted to resolving the question regarding compliance with the design and licensing basis. Region III is developing a plan/timeline for resolution and issuance of the inspection report.

NRC's Position o NRC issued CAL which included commitments to:

11 Determine root cause and develop a long-term monitoring program (due 2/28/12) 13 Select multiple un-cracked areas to investigate to verify the cracking is not spreading (due 90 days) 13 Analyze known cracked areas to verify the cracks are not growing o] Decision was made to leave code compliance questions out of the CAL and to focus on confirming assumptions made in the operability calculations

[I Focus on continued operability going forward 13 Address design through ongoing inspection 6

2/23/2012 License Renewal Impact S7 L

" The degraded shield building is a Part 50 issue affecting license renewal

" DLR needs to understand if the degradation is age-related, and if so how it will be managed o DLR will issue an RAI asking the applicant to explain how the unique OE will be addressed by its Aging Management Programs (AMP) 13 This will be tracked as an Open Item in the SER CR-3 Update: Timeline it 2

" Dec. 2008: License Renewal Application (LRA) submitted.

o Oct. 2009: Delamination of containment concrete in Bay 3-4.

"Mar. 2010: Applicant starts repair of concrete in Bay 3-4.

" Dec. 2010: SER issued with open item for containment repair.

"Jan. 2011: ACRS Subcommittee meeting.

5 Committee requested additional meeting after closeout of.

open item forcontainment repair.

"Mar. 2011: New delamination identified in containment Bay 5-6.

oJun. 2011: NRC informs the applicant that a revised schedule for LRA review will be established after information on the containment repair plan is submitted.

" Jul. 2011: Spalling and delamination identified in Bay 1-2.

n Concrete sections(approx. 1.5" x 12' x 3' & 5) fell on Intermediate Building 7

2/23/2012 CR-3 Update: Recent Activities

" Licensee reviewing repair proposals from Bechtel and URS 13 Anticipate contracts to be in place by Jan. 31 13 Repairs expected to require 2 to 3 years to complete 13 Detensioning currently on hold - will be included as part of the repair contract

" Licensee installed temporary anchors to limit propagation of delaminations and prevent future delaminations o Staff expects licensee to submit a license amendment but that is not certain at this point o Region II planning appropriate inspections during demolition, repair and testing 8

2/23/2012 CR-3 Update: Original Delamination I"5 Delamination..

October 2009 Buttress #4 Extent ofi

.. Repair/Replacement 57ft X 82ft Buttress #3 CR-3 Update: Original Delamination Delamination between buttress 3 & 4 9

2/23/2012 CR-3 Update: Possible Impacts on LR-AMPs V"I Program Impact Concrete and prestressing tendons: Enhanced inspection IWL and surveillance frequency; additional devices such as strain gauges to monitor cracks; and scanning of concrete at different locations.

10 CFR 50 App. J Containment Leakage Type A, B, and C tests: Test f e u ny frequency.

Tendons: Revision to the program and data since most of the vertical and hoop tendons will be re-tensioned.

Containment Tendons: Major revision to the program to identify sample Tendon Prestress size, frequency; new regression analysis based on re-tensioned data.

Comparison of Davis-Besse & CR-3 o Similar crack geometry

[] Laminar cracking around circumference of building o Similarities end there 10

2/23/2012 Differences Between Davis-Besse and CR-3 o Laminar cracking in the reinforced o Laminar cracking in the concrete shield building prestressed concrete

- containment building 0 Crack widths between 5 - 10 mils

" Crack widths between 125 -

0 Cracking along outer reinforcement 2750 mils mat (2-3" from exterior face)

" Cracking in the plane of o Root cause still under investigation horizontal prestressing tendons (8-9" from exterior face) o Cracking due to redistribution of prestressing forces, weak aggregate, and lack of radial reinforcement Summary

" Although similar at first glance, Davis-Besse and Crystdl River are different issues a Acceptance of one has no bearing on the other.

" Both issues are Part 50 concerns which have an impact on license renewal o The Regions and Headquarters will continue to work together to ensure continued functionality (Part 50) and to ensure aging is properly managed (Part 54) 11