ML12054A713

DRAFT- from James Clifford to Robert Nelson Request for Technical Assistance Seabrook Station ALKALI-SILICA Reaction, Draft 8 2010817

ML12054A713
Person / Time
Site:	Seabrook
Issue date:	02/16/2012
From:	Clifford J Division Reactor Projects I
To:	Nelson R Division of Policy and Rulemaking
References
FOIA/PA-2012-0119
Download: ML12054A713 (11)

Text

1' UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 475 Allendale Road King of Prussia, PA 19406 MEMORANDUM TO: Robert A. Nelson, Deputy Director Division of Policy and Rulemaking Q A' 1 )

Office of Nuclear Reactor Regulation FROM: James Clifford, Deputy Director Division of Reactor Projects

SUBJECT:

REQUEST FOR TECHNICAL ASSISTANCE SEABROOK STATION ALKALI-SILICA REACTION Region I requests technical assistance from the Office of Nuclear Reactor Regulation (NRR) to evaluate the potential consequence of alkali-silica reaction (ASR) degradation of a safety related concrete structure at Seabrook Station. More specifically, based on NRR review for adequacy of a NextEra prompt operability determination (POD) and its associated open issues, NRC staff should be able to identify what additional information is needed in order to fully evaluate the impact of the degradation on the current licensing and design basis in the final operability determination for impoe4antstructures important-to-safety at the plant. As aestthe primary case for review, the NextEra evaluation was for the Seabrook Control Building ("B" Electrical Tunnel and Penetration Room) in light of the recently discovered degradation mechanism. Other mpertda.t-strucutures important-to-safety within the scope of the maintenance rule afe-have also been affected by the ASR problem. Andthoy aro within the sc*po of the maint.nanc. rul. Accordingly, additional Task Interface Agreements may be necessary such as for a review of the final operability determination results for other buildings also exhibiting the ASR problem.

Background

NextEra (the licensee) analyzed concrete core samples from the interior surface of exterior walls of the Control Building as part of their assessment to support renewal of their license. In August 2010, tests undertaken as a part of the core sample analysis reported a change in material properties. The analysis reported the presence of aA(-ASR)-de radation in core samples taken from chronically wet walls below grade, with reductions reported in the concrete compressive strength and modulus of elasticity from that expected. NextEra evaluated these parametric reductions to determine the impact on the design basis of the Control Building. By their process, the licensee performed an immediate and prompt operability determination (POD) and concluded, preliminarily, that the Control Building (CB) was operable but with reduced strength reserves to design capacity.

NextEra continued to evaluate the extent of this condition for five other safety related concrete buildings. The other five buildings for which concrete core samples were taken were:

Equipment Vault (housing ECCS equipment including that for Residual Heat Removal (RHR)],

RCA (Radiological Controls Area) Walkway, Emergency Feedwater Building (EFW), Emergency

R. Nelson 2 Diesel Generator (EDG) Building, and the Containment Enclosure Building (CEB). As of June 30, 2011 there are two open prompt operability determinations, one for the Control Building and one for the other five buildings collectively. The licensee found additional evidence of ASR in four of the five other buildings and they evaluated that information in a separate immediate and prompt operability determination using the same evaluation techniques as for the Control Building, --the This evaluation is also considered preliminary or open. Based on NRC internal discussions, it appears that the calculation methods and correlations that NextEra used in their prompt operability determination may not be fully valid-appropriate in light of the ASR problem.

NextEra's planned actions are two-fold: 1) to follow their operability determination process; and,

2) to follow the guidance in NEI 95-10, "Industry Guideline for Implementing the Requirements of 10 CFR Part 54 - The License Renewal Rule," to develop an aging management program to support the license renewal application. Possible outcomes to the PODs are: 1) restored conditions (which may not be possible); 2) resolved conditions (use "as is" by procedure change incorporated or Action Request (AR) disposition approved); or 3) current licensing basis (CLB) revised (e.g., 10 CFR 50.59 evaluation)-. The licensee has posted on the Certrec internal website their operability determination process for reference (EN-AA-203-1001_005, No. 1 on Certrec Document Tab List)

NextEra's proposal related to license renewal was described in a letter dated April 14, 2011, under the response to NRC request for additional information B.2.1.31-1 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML11108A131). This letter describes periodic reviews for operability as information is developed to support the aging management review. At the time, the proposal included another analysis (termed "final" by NextEra) of the impact of ASR on the current licensing and design basis, including the extent of the condition, to be completed by June 2011. Since that letter and as noted above, the control building POD was kept open and a new immediate and POD were completed for the other five building core sample results. The subject NextEra letter also commits to an Engineering Evaluation to be completed in March 2012.

On June 29, 2011, the NRR Division of License Renewal issued another "Request for Additional Information" (ADAMS Accession No. ML11178A338) related to key aspects of NextEra's comprehensive plan for assessing the ASR problem for the Structures Monitoring Program including that for the Fuel Handling Building and Containment ("Followup RAI B2.1.31-1, B2.1.31-4, and B2.1.28-3). The response to this letter is due on or about August 13, 2011 and we expect it to reflect a comprehensive plan for determining operability/functionality of affected buildings along with plans for the development fet-of aging management review and program.

With respect to Part 50 requirements, Region I reviewed the NextEra current Structures Monitoring Program and found a violation of the maintenance rule for the control building. The finding is described in detail in NRC Inspection Report 05000443/2011002 (ADAMS Accession No. MLI 11330689). More details related to the newly discovered ASR issue were also documented in NRC Inspection Report 05000443/2011007 (ADAMS Accession No. ML111360432) as part of a license renewal inspection. The cover letter for the latter report notes that the aging management review for the ASR issue is not complete and that there is a need for a continuing review in the Part 50 and 54 areas. The staffs of Region I and NRR (Division of Engineering and Division of License Renewal) have been discussing actions since January 2011 to ensure that the Part 50 and 54 reviews are coordinated.

R. Nelson 3 The below listed documents were made available for review on the licensee's "Certrec" internal website. These documents reflect current NextEra view of operability for the Control Building and the associate tunnel and penetration room. The "Certrec" system was set up in order to facilitate NRC staff access to NextEra's internal documents. Pes!inforT Region I and 'Cortmwen [gi]: G-E-M: The d-ocumnent we NextEra if the document is to be printed, for review purposes, prior to doing sO.-................. review and any that are reviewed to form a staff decision need to be docketed.

1. (No. 2 on Certrec Document Library Tab List) C-S-1-10159 CALC 000, Rev. 0, 'B' Electrical Tunnel Transverse Shear Evaluation Supplement to Calculation CD-20 SComm printedntlbr review J - So

[T2-: plese refflect Documene tha toneed.

need cttw be

2. (No. 4 on Certrec Document Library Tab List) C-S-1-10150 CALC 000, Rev. 0, Effects of Reduce Modulus of Elasticity - 'B' Electrical Tunnel Exterior Walls

3. (No. 5 on Certrec Document Library Tab List) CD-20-CALC, UE Control and Dieisel Generator Building Design of Material and Walls below grade for Electrical Tunnel and the Control Building (Original Design Calculation)

4. (No. 6 on Certrec Document Library Tab List) Action Request (AR) 581434 Prompt Operability Determination Reduced Concrete Properties Below Grade in 'B' Electrical Tunnel Exterior Walls.

Also, before the startup of Seabrook from a refueling outage in May 2011, on April 27, 2011, NRR Division of Engineering provided support by performing an initial review ofing the following khdocument - AR No. 1644074 which documents NextEra's basis for a.ceptabil*. of the -COMMent [611: The document reviewd reduction in modulus of elasticity in light of concrete core testing using a[160 CFR 50.59 seanmed Inomplte, not of an Apperndx B qualty, and did not hae any signatures or screening process without prior NRC staff review and approval _This document has been nanee of prepare, revi-ewer and approver.

uploaded to the Certrec file and it is related to a design change document which accepts the C.m...mt [rT41: NRR/DE did not provided reduced parameters of compressive strength and modulus of elasticity for the Control Building support for reviewing the 50.59 screenilng and the Containment Enclosure Building as a potential disposition for the operability determination (No. 10 on Certrec Document Library Tab List, Enclosure Bldg and Control Bldg MSP - Design Change Package Description No. EC-272057, Rev. 000, Concrete Modulus of Elasticity Evaluation). M4Ihe screening process was questioned by NRCROILO& staffk, Subssauey. -NRR DE provided an initial list of questions as noted in the attachment (with one question being withdrawn - question No. 7.) ...............-........ .................................. - Coimnet [Grs): NRRDE did not review the 50.59 screening. Whet Is the relationship between questioning of th screening process The licensee is also planning an apparent cause review for the maintenance rule violation noted by 7??and the NRRIDE tecihnicl questions for above. Corrective actions include a comprehensive walkdown of all imfpoftnt structures them to be stated Inthe sarne seitence here?

important-to-safety with suspected ASR condition in accordance with a revised structures Please rephrase to put things Inthe correct perspective.

monitoring program procedure that meets the latest ACI standard in the area (ACI 349.3R-02).

This has been completed for the control building, containment enclosure building, and the containment but the completion dates for the other buildings is tentatively August to September 2011. Further, they-the licensee plans to conduct a root cause evaluation of the ASR issue and it-which should be completed in time for incorporation into the planned March 2012 Engineering Evaluation as noted above.

Licensee Position To date, within the limitations of their testing and analysis, NextEra determined that none of the seismic category I structures tested have been found to be outside their design basis and were, therefore, operable with extent of conditions questions needing be addressed. The Seabrook design and licensing basis to which the licensee made these determinations was documented in UFSAR Section 3.8. NextEra is willing to address the attached questions from DE; but, it is uncertain if those questions will be addressed in the final operability determination currently

R. Nelson 4 scheduled for September 30, 2011. NextEra will be providing a comprehensive plan on or about August 13, 2011, in response to NRC letter of June 29, 2011, as noted above.

In light of the newly discovered ASR issue, it appears that NextEra technical raviewers personnel are developing new insights for what key aspects must be addressed in the final operability determination for any building with evidence of ASR. NextEra is considering NRC staff questions to date and has hired consultants in this area. These consultants also will be developing a new model for the Containment Enclosure Building load analysis.

Requested Actions In order for Region I to independently determine operability of the control building or any other important-to-safety structure affected by the ASR problem; and, as a tst primarycase, we need a review for adequacy of the control building prompt operability determination and any related open issues as identified by NextEra. This information would be applied to the any final operability for the control building and any other affected important-to-safety structures. The important-to-safety structures are-theee-affected by the ASR problem aPd-are within the scope of the maintenance rule whielhand are also consistent with-the-within the scope fe--of license renewal. More specifically we need to independently develop a comprehensive set of issues to be applied to any final operability determination as a part of our oversight of the licensee's process and any new insights gained from NextEra's technical research.

Accordingly, Region I requests that NRR evaluate the adequacy of NextEra's control building prompt operability determination and its related open issues with particular focus, but not limited to, the below listed key technical questions. The licensee has provided a set of documents as noted on the reference Certrec website above but the NRR review should not be limited to those documents. Region I will facilitate ensuring that additional documents, as needed, are on the website or, as necessary, by an onsite inspection. NRR's determination should enable the staff to confirm that there is reasonable assurance of continued operability given the concrete degradation identified due to ASR for the control building once the final operability determination are made by NextEra for this or any other important structure affected by the ASR problem.

In the course of this review, Region I requests that NRR specifically identify any concerns with the assumptions, methodologies, or calculations, etc., along with the regulatory or other basis of each concern; and, notify Region I immediately if NRR finds that any of the reviewed documents for the control building do not provide reasonable assurance of continued operability of that building. As a minimum, the response to the TIA should include an independently developed comprehensive set of issues to be addressed in the final operability determination for the Control Building in order for us to further assess the licensee's process and their new insights I gained for all important-to-safety structures with evidence of ASR.

1. Do the referenced questions represent a comprehensive list of issues that need to be addressed in the final operability determination for the Control Building, given the current view of operability by NextEra as reflected in the prompt operability determination?

Discussion: The reference questions are those listed in the attachment of this document and those questions posted in the NRC RAI request for additional information [(ADAMS Accession No. MLI 1178A338) dated June 29, 2011, related to key aspects of NextEra's comprehensive plan for assessing the ASR problem for the Structures Monitoring Program including that for the Fuel Handling Building and Containment (Followup RAI B2.1.31-1,

R. Nelson 5 B2.1.31-4, and B2.1.28-3)]. If the issues are initially considered comprehensive, please give consideration to the below additional views produced by the regional technical staff. If the issues are not considered comprehensive, then identity those additional issues to be included with consideration to those listed below along with regulatory or other basis for the concern. An example would be the need for Poisson ratio calculations on core samples because there are assumed numbers in the UFSAR or the need for stiffness damage tests because of applicable ACI standard requires it in the current licensing basis.

2. What 's the Importanco of-re tensile strength mneasuremenAt6 reeuirodn core samples#o theffetedstrctuo?,and SR distinguish its imRportance for tersting related to the cOntro building vs. the coAinmeo4nt ... f ", t utfictn and technical A' for Disc ussioAn: N, tensile strength teSting is being pe*fermed on the.ncr.t. Rore sam*ples and this question wag- raised in the RAI.Q requ-est for info,.atr, in te,,,s of how shear capacity is being deteanined. HoweVer, the Region 1staff belie-%e that the specific paramoteir of tensile strength of cencrote may not be sufficien~tly accurate and thoroAforo relevant inaconstrained structure as the AS-R pressur~e load istransferred to the rebar.

Aalable... research in this area appea*s to be confc*ting. Forv example, using ASTM*

standards, the repor~ted tensileA VPUalues can Var,' kfro real values by uip to +/-40% and, as one resarcher raid, "... can hardly be assumed to be a Matc.ial pro.............to ranfr, the pressur~e contribution appears to be minimal (on the order ef less than 5% of the robar: yield based On preliminary research of liteature). Other papers incluiding the The UJFSAR f-9 con--ta-inmen-t assumne conrGete inreinforned-systems provide no tensile strength-.

Con.siderable research may be needed inorder to independent e a regulatory or

.tablish other basis in thos area.

!."Review of the splitting test standadrds from a fl~ractur moohanicS point Of View, C. ROcco, G.V.

GunaJ Planas, and M.ElicosO Facultad do Ingonioria, Univorsidad Nacional de 'a Plata, La Plata, Argentina, Departamento de Glendia de Matechales, Univemidad Politf§nira do Madrid, Madrid, Spain, 6 September t2000

3. WhAat isthe OFimIporAnce i aY&, Of obtaininq key para-meter te-st data by conductng confined

[ CommentIn[GIG included 6? this question implicly

]: int question 1 Discussion: hcoreiample with ASIR does aet e the frcS contained in the Apresent bcas strucWture, G--6 ifo Wei te parficr, olaltic rebound Isnot consideed FeR splth Commeat [G1M?: What is the test being I tensilene on cR tMe refensd here? I t are samples, th eidoenta inuece n the bated accommodated. The setieral lesses are ftinher etahod ' tSRestgn by theisf standardor abetoeeY praetive of placing plywoodmo oppoSine feaciA of the tensile apeimen tostea it forareusegm off t-he test stand, th us restraining axial exp ans io-n of the samWPlý.................... Comraat [ETS]: Idon't realiy understand this discussion In the context of the question. This discussion needs to be clarilied. Triatal testing 4-2. Because the original design basis assumes no ASIR is present during the design life of of core isvery rarely performed. The design the structure, what. if any. are the specific original design assumptions affected by the philosophy in the codes based on parameters presence of ASIR that are net clearly evident in the UFSAR design basis? obtained from normal core or cylinder tests do factor in confining or other 2D and 3D effects because the equations and provislons In the Discussion: For example several calculation methods such as the relationship between codes were developed based on extiesive testing Including real stucturai elements such compressive strength and modulus of elasticity to shear capacity and shear force are used as beams, stabs, columns, wail panels, frames in the seismic analysis. These assumed relationships may not be valid with ASR present in at.

the structure.

R. Nelson 6 5-3. What is the appropriate ACI standard to be used for degraded concrete core sampling assessing in-situ ASR degradation for the control building (locations, numbers, frequency of sampling in the future, etc)?

Discussion: While this is an issue raised in the attachment, we need to know the regulatory or other basis for the use of either of two applicable standards or other more appropriate standard. One standard is ACI 228 used by NextEra for correlation to penetration resistance probe data and the other is ACI 214 (version 1965 is referenced in the UFSAR section 3.8.2.4). It should be further noted that a later revision of ACI 214 (ACI-214.R-03) provides for additional sampling in order to achieve a 95% confidence level. The ACI 228 appears to be met by NextEra but it requires less sampling. These standards were developed for general design and construction of concrete structures for non-nuclear applications. Technical research may be needed in order to determine their relevance for nuclear application in which the structures are heavily reinforced with rebar. This leads to the next set of questions.

4A. Did NextEra adeauatelv-orform adeauate What in- the cGAPleoet set of laboratory tests for core sampling.-including appropriate parameters obtained along with laboratory test conditions?

Discausuicw Discussion: Also, during the course of this review, please identify the need for any in situ testing of control building conditions including appropriate parameters to be obtained such as temperature and humidity along with test conditions for now and in the future. Also, provide guidance on where and how much rebar should be exposed in order to assess the effect on rebar from the ASR issue.

- .- Formatted: Plain Text, Indent: Left: 0.25" No tensile strength testing is being performed on the concrete core samples and this question was raised in the RAI request for information in terms of how shear capacity is being determined. However, the Region I staff believe that the specific parameter of tensile strength of concrete may not be sufficiently accurate and therefore relevant in a constrained structure as the ASR pressure load is transferred to the rebar. Available research in this area appears to be conflicting. The UFSAR for containment assume concrete in reinforced systems provide no tensile strength.

.... Fo*rmattled: Plain Text, Indent: Left: 0.25" with ASR does not represent the forces contained in the structure because core sample for kis test in pAriglgr, 2estig Mbouod isnDt Ir~dereg Fgr Split tensile tsts on cre ------------ Conunart [On]. Mist is the tett being samples, the frictional influences in the test itself are not accommodated. The frictional refred hem?

losses are further exacerbated by the standard laboratory practice of placina plywood on oetosina faces of the tensile saecmen to stoe it from rollina off the test stand, thus restrainir axial expansion of the samle ..... Co..m* [GT1]: Idon't reay understand

7. What is the effect imeact of the alkali silic rcio dogAdtion On the Acurront And futur'e We discussicinIn fhacntextof the question.

with roQaads-to th bliyo tecn~trobildn to rocpcnd to design basis leads, including hnis aismon l neeas tobe da~mea. Taimnial tasting of cores vey- rnsty perfomnid. The seismnic eVents? design phosophy In the Code based on pararmetr obtained from nonral core or cylinder tt do factor Inconfinig or other 20 DiScuss6ion: Ne~dEra isplanning new modeling of the building loads including Gei6smic.A and 30 effe*ts bec**se t euatlions and rcviow of thA sei~mi analysis codos i6 beyond the current capability of the Region provisions In the codes were developed based technical staff. ThiA review should icuean ;assessment; of tho need to analyze the on extensive testing including reat strctural elements such as beams, slabs, columns, wall foundations alanA msgthe response of a whole stninturo when justthe foundation is panels, frames etc.

deg~aded.

R. Nelson 7 8-5.__Wow: vmll iQpd Next*ra AdugggiiWL FADov trcuoemnwrn rorris

n mne rji I rnt Nexttra Rtn ui rtni mnnitntrinn nr TKII*III nagffi,,iant ta &-iknvar rar Wrslirt4 ar~ieliinnsal ASR dam ru rtothdamae neatively impacting the design basis of the Cornunt [GT11J: Has NextERa issued a of the ASR problem? revisad InWoved structure. monitoring program (SMP)? Is the assessent of thear issu, at Seabrook beling perlbnned under the SMP Discussion: Durin. the neoti.t..n f . this;.r T.A it ha. b- ,,ome ncr4asina im.ortgnt for the Is a condition moniorng program) or

~(whch techni*c-al re,

• i.e,;ear to h -a'vethe initial s-t of building assessments. To date three building under toe Conuctive Acton Pogrm?

assessments have been comgLetedared-*ne" for the following buildings: control building, the containment, and the containment enclosure building. and are-aailable on site. These assessments were initiated as a consequence of discoveries made preparing- for a renewed license application. These discoveries should be reflected in enhancements to the programs required as part of the Maintenance Rule. The Region requests NRR assistance in evaluating the current acceptability of NextEra's programs to maintain the integrity of the safety related structures. SincAe the focus of this TIA is the control building that assessment

.. ould-b*he sampled in an upcoming inspe-tion to follow up on this open issue. An oppointunity m exist tc actually obseRa the iniial assessments being done on the other oay seis~mic structures from mid August to mid Seotembor:2011.

.......- Formatted: Plain Text, Indent: Left: 0.25" 1 Coordination This request was discussed between Richard Conte and his staff and Meena Khanna and her staff and Raender Auluck with hie staff along with Barry Miller (NRR) unnga _final conference Comment [T12r]: Does DLR needs to be call on ...... The TIA was accepted with an agreed upon response date within 90 days from the nlded here?

,*j last day of the technical reviewer's onsite review of the building initial assessments (item No. 8 above) and no later than 90 days from September 30, 2011. Region I will ensure the upcoming inspection is scheduled to end before September 30th. An additional TIA may be needed for the final operability for the control building and other buildings as they are completed. A final response would be dependent on the successful completion of the September 2011 inspection, otherwise, response dates will need to be renegotiated.

References http://ims.certrec.com (No. 2 on Certrec Document Library Tab List) C-S-1-10159 CALC_000, Rev. 0, 'B' Electrical Tunnel Transverse Shear Evaluation Supplement to Calculation CD-20 (No. 4 on Certrec Document Library Tab List) C-S-1-10150 CALC 000, Rev.. 0, Effects of Reduce Modulus of Elasticity - 'B' Electrical Tunnel Exterior Walls (No. 5 on Certrec Document Library Tab List) CD-20-CALC, UE Control and Deiesel Generator Building Design of Material and Walls below grade for Electrical Tunnel and the Control Building (Original Design Calculation)

R. Nelson 8 (No. 6 on Certrec Document Library Tab List) Action Request (AR) 581434 Prompt Operability Determination Reduced Concrete Properties Below Grade in 'B' Electrical Tunnel Exterior Walls.

http://portal.nrc.aov/edo/ri/EB1/Shared%20Documents/Forms/AllItems.aspx Docket No. 50-443 CONTACT: Michael Modes, DRS (610) 337-5198 ML111610530 SUNSI Review _ Complete V DOCUMENT NAME: G:\DRS\Engineering Branch 1\- MModes\TIA Seabrook ASR Draft docx

R. Nelson 9 Publicly Available Non-Publicly Available Sensitive Non-Sensitive To receive a copy of this document, indicate inthe concurrence box "C" = Copy,ihout attach/end; c h/end "N"= No copy OFFICE RI DRS RI DRS RI DRP RI IRS RI DRP NAME MModes RConte ABurritt PWilson DRoberts DATE 06/ /11 06/ /11 d= 06/ /11 , 06/ /11 06/ /11 i(QWJgJKL FROn _%QwY

R. Nelson 10 AftaohmeM DEiEMGS3 60MMRnTS An FAX46440jq r=VaIUa!'QR Of 6ORiaIRMgm ý=ngpswg An impoeantf- effect of reduction inelastic modulus (Ec) Of conrGete duo to ASIR is a rcduction in stiffness (axial, flexural, shear) of the affectod Warea relativo to the stiffness, of the un~affected a;reas. This would result in redistributfiopnof forces inthe global rFesponse of the stru-cturc u-nder design loads due to changes in the relative stiffnoss of the affeced and unaffected areas fromn that co-nnsiereAad- in the original global structur~al analy*ses f the CE using the SAG_computer codo. Fuher, since the ASR degr.adation in tR lo-wor

.h8 of the CEB, the reductioninelastic modulus could affect the

+reas boundaFr' conditionc assumod in the original analysis at the junction of the basemat and the CEB3 wall. Note tha~t FSAR Section 3.8.4..a states., in pant, that 4Lateral fores pro transferrd-to the fo-und-ation mats primjarily by the action of shear-walls; some load i also transtorroc by moans of #exural actWo ot the wag all of which are r;ýigi attached-of the mat." Also refer to pages 11 and 12 of Calculatin C S 1 10150.' T 'he'AR16440714 Evaluation does. net addrcss the effect of the reduced moedulus on tho global response of the stFructu.r. It a .ssumes that the forces. and in tho different elements Af the

.oments structurc under design loads remains the scme and only evaluates the local sections (concrete stresses, strains .. ad* exur.. capacity) for the reduced modulus, which are based 9on forces and moements fromA the original structural analysis.

2. The AR1614074 Eva'u-at*ion does not evaluate the effect of the reduced moduu's on the shear cGapaci. of the affected area.

3. The AR1644074 Evaluation does not address the effect ef the reduced modulus on the potential changes in the natural frequencies of the CGEB struc*tue, which could have effet the response of the stru-cture to seismic lead.

1. The AR1611071 Evaluation of the local section does not evaluate the #effetof reduced modulus on stress and strain in the rebar. The strain in the reb4ar could go beyond the yield strain. From page 17 ef Cole C= 14referenced iR the eauto fo.r elemen..t 255, the stress in the hoop rew .nforement is.651.43 ksi, whiGh is already beyond yield.

5. The ARI 644074 Evaluation of the loal section is based on element 255, which is 27" thick and appears to be outside the area affected by ASR The areas affected by ASR appear tobe.At the lowe..r elevati f the CEB whichare36"h.i..ck....

2 A. critical element in the affected area needs to be evaluated. Fuiher, note th+at the forces and momens#in element 255 could increase based on eomment 1 above, and thereby futher afect crncroto a;nd rbah;r stresses a;nd strains inelement 255E

6. The IARK164I407 I II *a tvaiuation goes. not exliciGtly evaluate the eflect ot the reduced

• A ,

moauius en the flexurci capacGIW ot Oflcta Iecai sections. nut makes reterenc-e to Colei'

R. Nels on 11

• S 110160 pe4oRmed for the electrical tunneI ... heffect-on flexural capacity of the

,r-ra, O U*[: 01 OttIW -.- snouu Oxpicifly IO evauatep since tno efect OTme reouce' Moduu I-is on moment capa tity of a section, it a fun-tion of the aount of reinforcemen i,-

the secton, the setrion dimensiotns a materi ind oeriete Cm Ewall reinforemoent, dimensions tand mater rirtopffert from4that of the electFrial tunrel.

7. On page 2 of the AR1617071 Evaluation,-it is stated that "The reductiotin Es tca the neutral axis of the balanced conrGeto and reinforcing steel s o tohift tQoward the tninreinOforc~ing steel." it appears that the re-d-uct-ion in Es would tend to cause the neutral axis to shift toward the extremie compression fiber that the tension reinforcing steelpeF-T Per eorg Thoas tlecn of June 9, 2010-with R.Conte.0

8. To have anly level of statistical validity, the nubrof cor-es useAd in evaluaion WOn should be at least 3. The A.R16140-71 Evaluation uses resul1ts barsed on only 2 core tests of the ASR affected area.

0. What are the strain levels attorpoe aues Of concro(te comnpressive st9renth and eatcMoAdulus6 from core tests reported in Table 1 of ARI6'11071? Does petrographic examinatien of the cores indicate ASR through the thickness of the wall.

10. The AR1 6d4074Aevaluiiation rshouwld- imnclude a problem statoment desriFption of the cniinbeing evaluated and its preliminar,' extent (at least based on visual inspectionI) foar the s.truclture in question so that an outside reviewer can understand what is being evaluated-