ML12213A348
| ML12213A348 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/28/2011 |
| From: | Office of Information Services |
| To: | |
| References | |
| FOIA/PA-2012-0121 | |
| Download: ML12213A348 (16) | |
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Table of Contents Page CR-2011-04507 1 CR-2011-04507 (Attachments) 5 CR-2011-04507 8 CR-2011-04507 9 Form # FORM-2011-04507-1 10 Form # FORM-2011-04507-1 (Attachments) 11 CR-2011-04507 14
H e ade r.
- -F CR Identifier,' Origination Date Owning Organization On -rginator's na. De a t m n -
Department CR-2011-04507 10/28/2011 IDB-EN-DESN IDB-EN-DESN Site:' Unit Category IDue Date G201 I1 AF 112/01/2011 Title Isolated crack indication identified by Impulse Response Testing of the Shield Building Discover Date Discover Time Event Date . EventTimeý:-
10/28/2011 08:31 10/28/2011 08:31 Functional Location - System Functional Location Equipment Description AP-913 EP Equipment Identified By QA Finding? SROReview Required but Individual No Initially Skipped.
Condition Report Description of Condition and Probable Cause Impulse Response (IR) testing is being used to help located below the surface concrete cracking. CR 2011-03346 was written to identify
'cracking in the architectural flute shoulder area. CR 2011-04402 was written to identify cracking in the main steam line room.
This CRis being written to document and evaluate three small isolated areas identified by the Impulse Response testing that are located in the architectural flute shoulder areas but not part of CR 2011-03346 and a core sample that contained a vertical crack.
IR location with small isolated areas that indicate subsurface deformities/ imperfections:
Shoulder 10 approximate 212 azimuth and elevation 673 Shoulder 13 approximate 285 azimuth and elevation 618 Shoulder 15 approximate 330 azimuth and elevation 664 In addition, Core bore "M" F7 (Flute at 292.50 azimuth and elevation 633) contained a vertical radial crack.
Immediate Actions Taken Informed Problem Solving Decision Making team Recommended Actions Initial Reviews 2 Contact Jon Hook Supervisor Comments This CR documents additional cracks in the Containment Shield Building during the extent of condition activities for CR 2011-03346.
Recommend this CR be closed to CR 2011-03346.
Is this arequires which consequential Human Performance Error/Event SRO Review'Required?
a Quick Human Performance Checklist? Yes No MRB Comments-'
MRB Questions A CARBW. EME IOE. IGC EFC MRW - MR IPE '
0 Pre-job Brief Date EACE Required? HPCL Needed?
09/27/2011 Investigation/Closure Summary .
Investigation 1-Abstract 2-Introduction 1 of 15
2.1-Problem Statement 2.2-Consequences 3-Data Analysis 3.1-Methodology 3.2-Sequence of Events 3.3-Discussion 4-Latent Organizational Weakness Evaluation 5-Generic Implications 5.1-Plant and Industry Experience 5.2-Extent of Condition 6-Ap parent and Contributing Cause(s) 7-Corrective Action Plan 8-References 9-Attachments Corrective Actions Taken PROBLEM STATEMENT CR 2011-03346 was written to document cracking in the architectural flutes shoulder area, and CR 2011-04402 was written to document cracking in the main steam line room. During impulse response (IR)testing for the investigation into the extent of concrete cracking identified by CR 2011-03346, several small isolated areas indicated subsurface imperfections were identified. These locations are at the edge or slightly beyond the-thicken-wall area of the architectural flute shoulder. The isolated areas with subsurface imperfections are identified.as follows: *.
1.Shoulder 10 approximate 212 azimuth and elevation 673 (S10-672-35) 2.Shoulder 13 approximate 285 azimuth and elevation 618 3.Shoulder 15 approximate 330 azimuth and elevation 664 In addition to the IR indication, a vertical radial crack was identified in the core bore located at Core Bore "M" in Flute #7.
INVESTIGATION See Attached Investigation Form PAST OPERABILITY Based on the evaluation above, these indications and cracks have a negligible structural impact on the shield building. Therefore, the shield building will continue to meet its design function.
2 of 15
CORRECTIVE ACTIONS None Required Corrective Actions-Pla.nned None Hardware I Degraded Condition Resolution Required -
No Does-the CR involve information obtained oran observation made of a BASIC COMPONENT that could compromise safetv?
No ANII Review? . .
No Review .
Review Level K Review Results Additional Review- Approved w/ . Date . ,Comments Comments Peer Review Approved Y 11/01/2011 No Peer Review necessary, this was downgraded from a Full Apparent Cause Evaluation to a fix.
This peer was done for the fix.
Manager Approval Approved 11/01/2011 CARB Review Forms Form,# 'Form/Document' Assigned Org/leam . - Due Date, Status * ,,Result 1 Other Supporting Document DB-EN-DESN-MS 111/01/2011 lComplete Downgrade Requests Downgrade Request' Initiated On Original Category iF Proposed Category Status Click to view 11/01/2011 10:58 AA AF Approved NPO'Code INPO Code NO INPO CODE Event Codes Event Code EQO05; EQUIPMENT OPERATION / STRUCTURAL DEGRADATION -- Equipment operation degraded, (such as leaks, vibration, makes noise, runs hot, or is out of...
Activity / Process/ Cause Codes Activity Code Related Process Code Cause Code Data Component Type Component Number Related Corrective Actions 0575; COMPONENT HDW DEGRADATION --
Hardware deficiencies where a component is degraded but still able to perform its primary function. I Workbook Events Event Status Assigned to Created by Created on -Finished by Finished on Initiate Completed Hook, Jon Hook, Jon 10/28/2011 08:48 EDT Hook, Jon 10/28/2011 08:48 EDT Supervisor Completed Hook, Jon Hook, Jon 10/28/2011 08:48 EDT Hengge, Craig 10/28/2011 15:12 EDT Review SRO Review Completed CR Holding Tank Hengge, Craig 10/28/2011 15:12 EDT AUTO- 10/28/2011 17:04 EDT GENERATED MRB Review Completed CR CRPA Team - AUTO- 10/28/2011 17:04 EDT Baker, Katie 10/29/2011 13:35 EDT G201 GENERATED Assign Closure Skipped Baker, Katie 10/29/2011 13:35 EDT Baker, Katie 10/29/2011 13:35 EDT Summary Closure Skipped Baker, Katie 10/29/2011 13:35 EDT Baker, Katie 10/29/2011 13:35 EDT Summary Pre-job Brief Completed Hook, Jon Baker, Katie 10/29/2011 13:35 EDT Hook, Jon 11/01/2011 17:58 EDT Investigation Skipped Hook, Jon 11/01/2011 17:58 EDT Hook, Jon 11/01/2011 17:58 EDT Peer Review Reassigned Hook, Jon Hook, Jon 11/01/2011 17:58 EDT Johnson, John 11/01/2011 18:11 EDT Peer Review Cancelled McCloskey, Johnson, John 11/01/2011 18:11 EDT Bingham, Peter 11/01/2011 18:53 EDT Patrick 3 of 15
.. Workbook Events Event, Status Assigned to,' Created by Created on Finishedby 9 Finished on Closure Completed Reineck, Bradley Bingham, Peter 11/01/201118:53 EDT Reineck, Bradley 11/01/2011 19:06 EDT Summary _
Pre-job Brief Skipped Reineck, Bradley 11/01/2011 19:06 EDT Reineck, Bradley 11/01/2011 19:06 EDT Investigation' Skipped Reineck, Bradley 11/01/2011 19:06 EDT Reineck, Bradley 11/01/2011 19:06 EDT Peer Review Skipped Reineck, Bradley 11/01/2011 19:06 EDT Reineck, Bradley 11/01/2011 19:06 EDT Manager Completed Hook, Jon Reineck, Bradley 11/01/2011.19:06 EDT Hook, Jon 11/01/2011 19:21 EDT Approval Root Cause - Skipped -.. Hook, Jon 11/01/2011 19:21 EDT Hook, Jon 11/01/2011 19:21 EDT Sponsor I QA Review Skipped Hook, Jon 11/01/2011 19:21 EDT Hook, Jon 11/01/2011 19:21 EDT CARB Review Working CR CRPA Team - Hook, Jon 11/01/2011 19:21 EDT
_ . _ G201 _ I
... Attachments
,Attachment, 12011-04507 Final.doc 4 (5f 15
PROBLEM STATEMENT CR 2011-03346 was written to document cracking in the architectural flutes shoulder area, and CR 2011-04402 was written todocument cracking in the main steam line room.
During impulse response (IR) testing for the investigation into the extent of concrete cracking identified by CR 2011-03346, several small isolated areas indicated subsurface imperfections were identified. These locations are at the edge or slightly beyond the thicken wall area of the architectural flute shoulder. The isolated areas with subsurface imperfections are identified as follows:
- 1. Shoulder 10 approximate 212 azimuth and elevation 673 (S1O-672-35)
- 2. *Shoulder 13 approximate 285 azimuth and elevation 618
- 3. Shoulder 15 approximate 330 azimuth and elevation 664 In addition to the IR indication, a vertical radial crack was identified in the core bore..
located at Core Bore "M" in Flute #7.
INVESTIGATION Since these three IR indications and the vertical crack are not addressed within the scope of CR 2011-03346 and CR 2011-04402, the IR indications and vertical crack shall be investigated by this CR.
The IR test results, core bore results, and the Bechtel Technical Assessment Report
- 25539-200-COR-0000-00001 (TAR) are included in the Root Cause Report for CR 2011-03346. Per review of the IR test report, the isolated areas with potential subsurface imperfections range in area of approximately 1 square foot to 4 square feet.
A core bore (S10-672-35) was drilled near the indication identified in shoulder #10. A laminar crack was confirmed at 1" from the outside surface of the shield building. Since the crack is only 1" from the surface, the crack remains outside the outer layer of structural reinforcing steel and adequate concrete cover remains. During a walkdown of this area, several minor tight surface cracks were identified in close proximity to the core bore. These surface cracks were of short length less than three feet. Inspection of these cracks indicates that the crack is sloping toward the core bore area. Minor surface cracks are not uncommon in concrete and do not affect the overall structural capacity of the structure. There was no spalled concrete or signs of staining at these surface cracks which would indicate corrosion of reinforcing steel. Therefore, based on the location and the slope of the surface cracks, the crack being one inch below the surface, adequate concrete cover for the reinforcing steel, no signs of reinforcing steel corrosion, and the localized indication is surrounded by sound concrete, there is no adverse affect on the structural capacity of the shield building. Based on the above, the Impulse Response.
reading in this area can be attributed to the local surface cracking.
5 of 15
The indication identified by the Impulse Response testing in shoulder #13 is a couple feet south of the original construction opening right edge and a couple of feet below the top edge. Per drawing C-i 12, this area contains a significant amount of additional reinforcing steel from the. original construction opening. Therefore, the most likely cause for this isolated indication may be attributed to localized poorly consolidated concrete during initial concrete placement in this heavily reinforced area. A walkdowiAn of this area did not identify any spalled concrete, surface cracks, or staining in the immediate area. :The indication is localized to an area less than four square feet. Since the original construction opening has been filled, the additional opening reinforcing steel adds strength to this area. Based on the good surface condition of the area, the localized area, the additional strength from opening reinforcing steel, the structural impact on the shield building is considered negligible.
The indication identified in shoulder # 15 is located approximately 13 feet south of the edge of the architectural flute. This indication is approximately one square foot and is slightly beyond the shoulder area and the additional shoulder reinforcing steel. A field walkdown of this area identified some minor surface cracks in close proximity to the Impulse Response test reading. These surface indication can and do adversely affect the readings, which could indicate an imperfection in wall. The surface area immediately, surrounding this indication did not reveal any abnormal surface imperfections and the Impulse Response in the surrounding area indicate sound concrete. Therefore, based on the Impulse Response indication being an isolated point (one square foot), several surface cracks in the vicinity of the reading and sound concrete beyond this indication, the indication appears to be attributed to the localize surface cracking. The walkdown of this area found no spalled concrete or signs of staining at these surface cracks which would, indicate corrosion of the reinforcing steel and the concrete surface appeared sound.
Therefore, based on the above, there will be no impact on the structural capacity of the shield building, The crack identified in core bore F7(M) appears to be a tight vertical radial crack rather than a laminar crack. The crack is seen at a depth of approximately 8 inches on one side of the core bore and at a depth of approximately 18 inches on the other side. Based on field walkdown of this core bore with the boroscope, a crack wasnot observed. The core.
bore was not wetted, which may explain why the crack was not observed. Therefore, if a crack does exists the width will be less than 0.005" which is the smallest crack width measured on the crack comparator. A crack this small is much tighter than the laminar cracks found in most of the other core bores obtained for CR 2011-03346 investigation and a crack of this width is also well within any limitations described within the ACI code. Due to the low tensile strength in concrete, cracks in concrete can never be completely eliminated. Radial cracks, such as the crack identified in this core bore, are commonly caused by concrete shrinkage during the curing process or other thermal gradients. One of the functions of reinforcing steel is to limit the size of these types of cracks. Since the wall is well reinforced with at least #10 bars every 12 inches, there is well confinement of this crack. In addition, core bores were installed in the immediate area of this core bore in the shoulder area. These core bores did not identify any cracks.
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Therefore, there is no apparent connection between this vertical crack and the laminar cracks found in the adjacent shoulder area. Therefore, based on theabove, the vertical crack identified within core bore F7(M) will not impact the structural capacity of the shield building and does not present a structural concern.
PAST OPERABILITY Based on the evaluation above, these indications and cracks have a negligible structural impact 'of the shield building. Therefore, the shield building will continue to meet its design function.
CORRECTIVE ACTIONS None Required 7 of 15
11/04/2011 12:3 FrT CRI-ISRO Review.
CR Site Unit PFA Current Power LeVel Current Power Level, CR-2011-04507 G201 1 Requested?. Mode (Unit : (Unit 1) . Mode (Unit (Unit 2)
No. 1 0 2). " 1 Defueled Peer Reviewer Horvath, Eric A.
SRO Comments As stated in the Supervisory Comments this Condition Report will be close to Condition Report 2011-03346. Therefore, Tech Spec Equipment Operable has been marked N/A. Reportable has been marked NO.
CR Originator Jon; Hook; 14268 Immediate Actions Taken Informed Problem Solving Decission Making team Tech Spec Equipment Operable?
N/A Immediate lnvestigation Required? :*
No Mode Hold Restraint?
No Plant Condition Restraint?
No EP Equipment Category?
N/A Past Operability Review?
No Reportable?
No CR Description Impulse Response (IR) testing is being used to help located below the surface concrete cracking. CR 2011-03346 was written to identify cracking in the architectural flute shoulder area. CR 2011-04402 was written to identify cracking in the main steam line room.
This CR is being written to document and evaluate three small isolated areas identified by the Impulse Response testing that are located in the architectural flute shoulder areas but not part of CR 2011-03346 and a core sample that contained a vertical crack.
IR location with small isolated areas that indicate subsurface deformities/ imprefections:
Shoulder 10 approximate 212 azimuth and elevation 673 Shoulder 13 approximate 285 azimuth and elevation 618 Shoulder 15 approximate 330 azimuth and elevation 664 In addition. Core bore "M" F7 (Flute at 292.50 azimuth and elevation 633) contained a vertical radial crack.
Supervisor Comments This CR documents additional cracks in the Containment Shield Building during the extent of condition activities for CR 2011-03346.
Recommend this CR be closed to CR 2011-03346.
Functional Location System Functional Location Equipment Description AP-913 I. EP Equipment, Event Status Assigned to Created by Created on Finished by Finished on Initiate Completed Hengge, Craig Hengge, Craig 10/28/2011 15:12 EDT Hengge, Craig 10/28/2011 15:12 EDT Unit 2 SRO Skipped Hengge, Craig 10/28/2011 15:12 EDT Hengge, Craig 10/28/2011 15:12 EDT Review Unit 1 SRO Completed CR SRO Review Hengge, Craig 10/28/2011 15:12 EDT Rayburn, William 10/28/2011 16:55 EDT Review Team - G201 (Unit 1)
Close Completed I Rayburn, William 10/28/2011 16:55 EDT Rayburn, William 10/28/2011 16:55 EDT 8 of 15
" ' .. ............ 11/04/2011 1 2-1:k'Fn]
Header CR - Reportability Review CR-2011-04507 RepOrtable? FLOC System FLOC No Re6drtability Determination LER 1 ILER2 .LER3 ILER4A Supervisor Comments This CR documents additional cracks in the Containment Shield Building during the extent of condition activities for CR 2011-03346.
Recommend this CR be closed to CR 2011-03346.
SROComments As stated in the Supervisory Comments this Condition Report will be close to Condition Report 2011-03346. Therefore, Tech Spec Equipment Operable has been marked N/A. Reportable has been marked NO.
Event Statui Event~~ 0 Workbook Events Fiih- b,
__.... Fnshed on ,..
_Event_ ...... _ _Status_:'_
_ _ Assignedt * 'Created by Created on Finished by Finished on Initiate Completed Hook, Jon AUTO- 10/28/2011 17:07 EDT AUTO- 10/28/2011 17:07 EDT GENERATED GENERATED Reportability Completed CR Reportability AUTO- 10/28/2011 17:07 EDT Wolf, Gerald 10/29/2011 14:42 EDT Review Review Team - GENERATED Close Completed __G201 __Wolf, Gerald 10/29/2011 14:42 EDT IWolf, Gerald 110/29/2011 14:42 EDT 9 of 15
"' ' :11 /n412011 12:t3 Frn CR - Formrs ~ 'f Header~
CR : .. Form # Site Doci4ment! ypei lAssigned Organization CR-2011-04507 FORM-2011-04507-1 G201 Other Supporting Document DB-EN-DESN-MS; DB-Mech/Structural Engr Due Date -. .
11/01/2011 .
Description . - .
Investigation Form Attached * -
Response --
- . Workbook Events.
Event Status Assigned to Created by- : Mý,Created on Finished by Finished on Initiate Completed Reineck, Bradley Reineck, Bradley 11/01/2011 14:51 EDT Reineck, Bradley 11/01/2011 14:51 EDT Assign Skipped Reineck, Bradley 11/01/2011 14:51 EDT Reineck, Bradley 11/01/2011 14:51 EDT Attach Completed Osting, Steven Reineck, Bradley 11/01/2011 14:51 EDT Reineck, Bradley 11/01/2011 14:51 EDT Approve Skipped Reineck, Bradley 11/01/2011 14:51 EDT Reineck, Bradley 11/01/2011 14:51 EDT Close Completed Reineck, Bradley 11/01/2011 14:51 EDT Reineck, Bradley 11/01/2011 14:51 EDT 10 of 15
PROBLEM STATEMENT CR 2011-03346 was written to document cracking in the architectural flutes shoulder area, and CR 2011-04402 was written to document cracking in the main steam line room.
During impulse response (IR) testing for the investigation into the extent of concrete cracking identified by CR 2011-03346, sdveral small isolated areas indicated subsurface imperfections were identified. These locations are at the edge or slightly beyond the thicken wall area of the architectural flute shoulder. The isolated areas with subsurface imperfections are identified as follows:
- 1. Shoulder 10 approximate 212 azimuth and elevation 673 (Si 0-672-35)
- 2. Shoulder 13 approximate 285 azimuth and elevation 618
- 3. Shoulder 15 approximate 330 azimuth and elevation 664 In addition to the IR indication, a vertical radial crack was identified in the core bore located at Core Bore "M" in Flute #7.
INVESTIGATION Since these three IR indications and the vertical crack are not addressed within the scope of CR 2011-03346 and CR 2011-04402, the IR indications and vertical crack shall be investigated by this CR.
The IR test results, core bore results, and the Bechtel Technical Assessment Report
- 25539-200-COR-0000-00001 (TAR) are included in the Root Cause Report for CR 2011-03346. Per review of the IR test report, the isolated areas with potential subsurface imperfections range in area of approximately 1 square foot to 4 square feet.
A core bore (S 10-672-35) was drilled near the indication identified in shoulder #10. A laminar crack was confirmed at 1" from the outside surface of the shield building. Since the crack is only 1" from the surface, the crack remains outside the outer layer of structural reinforcing steel and adequate concrete cover remains. During a walkdown of this area, several minor tight surface cracks were identified in close proximity to the core bore. These surface cracks were of short length less than three feet. Inspection of these cracks indicates that the crack is sloping toward the core bore area, Minor surface cracks are not uncommon in concrete and do not affect the overall structural capacity of the structure. There was no spalled concrete or signs of staining at these surface cracks which would indicate corrosion of reinforcing steel. Therefore, based on the location and the slope of the surface cracks, the crack being one inch below the surface, adequate concrete cover for the reinforcing steel, no signs of reinforcing steel corrosion, and the localized indication is surrounded by sound concrete, there is no adverse affect on the structural capacity of the shield building. Based on the above, the Impulse Response reading in this area can be attributed to the local surface cracking.
11 of 15
The indication identified by the Impulse Response testing in shoulder #13 is a couple feet south of the original construction opening right edge and a couple of feet below the top edge.. Per drawing C- 112, this area contains a significant amount of additional reinforcing steel from the original construction opening. Therefore, the most likely cause for this isolated indication may be attributed to localized poorly consolidated concrete during initial concrete placement in this heavily reinforced area. A walkdown of this area did not identify any spalled concrete, surface cracks, or staining in the immediate area. The indication is localized to an area less than four square feet. Since the original construction opening has been filled, the additional opening reinforcing steel adds strength to this area. Based on the good surface condition of the area, the localized area, the additional strength from opening reinforcing steel, the structural impact on the shield building is considered negligible.
The indication identified in shoulder # 15 is located approximately 13 feet south of the edge of the architectural flute. This indication is approximately one square foot and is slightly beyond the shoulder area and the additional shoulder reinforcing steel. A field walkdown of this area identified some minor surface cracks in close proximity to the Impulse Response test reading. These surface indication can and do adversely affect the readings, which could indicate an imperfection in wall. The surface area immediately surrounding this indication did not reveal any abnormal surface imperfections and the Impulse Response in the surrounding area indicate sound concrete. Therefore, based on the Impulse Response indication being an isolated point (one square foot), several surface cracks in the vicinity of the reading and sound concrete beyond this indication, the indication appears to be attributed to the localize surface cracking. The walkdown of this area found no spalled concrete or signs of staining at these surface cracks which would indicate, corrosion of the reinforcing steel and the concrete surface appeared sound.
Therefore, based on the above, there will be no impact on the structural capacity of the shield building, The crack identified in core bore F7(M) appears to be a tight vertical radial crack rather than a laminar crack. The crack is seen at a depth of approximately 8 inches on one side of the core bore and at a depth of approximately 18 inches on the other side. Based on field walkdown of this core bore with the boroscope, a crack was not observed. The core bore was not wetted, which may explain why the crack was not observed. Therefore, if a crack does exists the width will be less than 0.005" which is the smallest crack width measured on the crack comparator. A crack this small is much tighter than the laminar cracks found in most of the other core bores obtained for CR,2011-03346 investigation and a crack of this width is also well within any limitations described within the ACI code. Due to the low tensile strength in concrete, cracks in concrete can never be completely eliminated. Radial cracks, such as the crack identified in this core bore, are commonly caused by concrete shrinkage during the curing process or other thermal gradients. One of the functions of reinforcing steel is to limit the size of these types of cracks. Since the wall is well reinforced with at least #10 bars every 12 inches, there is well confinement of this crack. In addition, core bores were installed in the immediate area of this core bore in the shoulder area. These core bores did not identify any cracks.
12 of 15
Therefore, there is no apparent connection between this vertical crack and the laminar cracks found in the adjacent shoulder area. Therefore, based on the above, the vertical crack identified within core bore F7(M) will not impact the structural capacity of the shield building and does not present a structural concern.
PAST OPERABILITY Based on the evaluation above, these indications and cracks have a negligible structural impact of the shield building. Therefore, the shield building will continue to meet its design function.
CORRECTIVE ACTIONS None Required 13 of 15
11 /Nt/') n1 1 1 -).-:t'A PrnT
~CR -DoWngrades -
Header-4 CR lOriginal Proposed, QA Finding Originator Assigned Org Current Due Disposition-CR-2011-04507 Category Category., No Hook, Jon G. DB-EN-DESN Date - - Approved AA AF 11/27/2011 CR Description -
Impulse Response (IR) testing is being used to help located below the surface concrete cracking. CR 2011-03346 was written to identify cracking in the architectural flute shoulder area. CR 2011-04402 was written to identify cracking in the main steam line room.
This CR is being written to document and evaluate three small isolated areasidentified by the Impulse Response testing that are located in the architectural flute shoulder areas but not part of CR 2011-03346 and a core sample that contained a vertical crack.
IR location with small isolated areas that indicate subsurface deformities/ imprefections:
Shoulder 10 approximate.212 azimuth and elevation 673 Shoulder 13 approximate 285 azimuth and elevation 618 Shoulder 15 approximate 330 azimuth and elevation 664 In addition, Core bore "M" F7 (Flute at 292.50 azimuth and elevation 633) contained a vertical radial crack.
Reason for Downgrade Based on an inspection of all four areas, the isolated areas are all acceptable and do not affect the structural design or capacity of the shield building Justification Core Bore S10-672-35 had a laminar crack identified 1" from the concrete surface. During an inspection of the immediate area of the core bore, a small localized surface crack less than three feet in length is in close proximity to the core bore. The slope of this crack is toward the core bore. There was no signs of spalled concrete or signs of staining at these surface cracks. Based on the location and slope of the surface cracks, the crack being one inch below the surface, adequate concrete cover for the reinforcing steel, no signs of reinforcing steel corrosion, and the localized indication is surrounded by sound concrete, there is no adverse affect on the structural capacity of the shield building. Based on the above, the Impulse Response reading in this area can be attributed to the local surface cracking.
Indication identified by the Impulse Repose testing in Shoulder #13 is adjacent to the original construction opening. This area contains a significant amount of additional reinforcing steel from the original construction opening. Therefore, the most likely cause for this isolated indication may be attributed to localized poorly consolidated concrete during initial concrete placement in this heavily reinforced area.
Since the original construction opening has been filled, the additional opening reinforcing steel adds strength to this area. Based on the good surface condition of the area, the localized area, the additional strength from the opening reinforcing steel, the structural impact on the shield building is considered negligible.
Indication identified in shoulder #15 is located above the RVCH opening (2011). This indication is approximately one square foot and is surrounded by sound concrete. A field walkdown of this area identified some minor surface cracks in close proximity to the Impulse Response test reading. The surface indication can and do adversely affect the readings, which could indicate an imperfection in the wall.
Based on the Impulse Response indication being an isolated point, several surface cracks in the vicinity of the reading and sound concrete beyond this indication, the indication can be attributed to the localized surface cracking. Therefore, based on the above, there will be no impact on the structural capacity of the shield building.
A vertical radial crack was identified in core bore F7 (M). This crack is a very tight crack (<0.01 inch). Due to low tensile strength in concrete, cracks in concrete can never be completely eliminated. Radial cracks, such as this are commonly caused by concrete shrinkage during the curing process or other thermal gradients. One of the function of reinforcing steel is to limit the size of these types of cracks.
Since the wall is well reinforced with at least #10 bars every 12 inces, there is well confinement of this crack. In addition, core bores installed in the immediate areaa did not find a connection between this vertical crack and the laminar crack found in the adjacent shoulder area. Therefore, based on the above, the vertical crack identified within core bore F7 (M) will not impact the structural capacity of the shield building and does not present a structural concern.
Manager Comments MRB Comments The MRB approved this downgrade on 11/1/11 Reference any rolled CRs and CAs that have been rolled into this evaluation requesting down-grade.. ..
Workbook Events Event Status Assigned to Created by Created on Finishedlby ' Finished on -
Initiate Completed Hook, Jon Hook, Jon 11/01/2011 10:58 EDT Hook, Jon 11/01/2011 10:58 EDT QA Approval Skipped Hook, Jon 11/01/2011 10:58 EDT Hook, Jon 11/01/2011 10:58 EDT Manager Completed Hook, Jon Hook, Jon 11/01/2011 10:58 EDT Hook, Jon 11/01/2011 10:59 EDT Approval 14 of 15
- Workbook Events _ _ _ _ _ _
..Event Status Assigned to 'Created by Created on Finished byV-,- Finished on Manager Completed Hook, Jon Hook, Jon 11/01/2011 10:58 EDT Hook, Jon 11/01/2011 10:59 EDT Approval MRB Approval Completed CR CRPA Team - Hook, Jon 11/01/2011 10:59 EDT Hook, Jon 11/01/2011 10:59 EDT G201 Close Completed Hook, Jon 111/01/2011 10:59 EDT Hook, Jon 11/01/2011 10:59 EDT 15 of 15