ML12173A462

Draft Letter from D. Roberts, Region I to J. Jolicoeur, NRR; Subject: Request for Technical Assistance, Seabrook Station Alkali-Silica Reaction

ML12173A462
Person / Time
Site:	Seabrook
Issue date:	06/04/2012
From:	Darrell Roberts Division Reactor Projects I
To:	John Jolicoeur Licensing Processes Branch (DPR)
References
FOIA/PA-2012-0119
Download: ML12173A462 (6)

Text

N(KRR, 0r-z UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 475 Allendale Road King of Prussia, PA 19406 MEMORANDUM TO: John Jolicoeur, Deputy Director Division of Policy and Rulemaking Office of Nuclear Reactor Regulation FROM: Darrell J. Roberts, 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 Gectural effects and management of alkali-silica reaction (ASR) degradation ofat S .eab(r_9o9k_Station, andto evaluate the -----------

impact of the degradation on the current licensing and design basis.

Background

NextEra analyzed concrete _ore samples from the interior surface of exterior walls of the commet [2]: Pleas. inciud.

Control Building as part of their materiai condition assessment fcon-crete-stru-tures -to support how the de~grade a stslterentof]

condition was first lenffijdto' renewal of their license. In August 2010 tests, undertaken as a part of the core sample and what led to the core sampiea being Wo~n, analysis, reported a change in material properties. The analysis reported the presence of alkali-silica-reaction ASR in core samples taken from chronically wet walls below grade, with apparent r.seported in the concrete compressive strength and modulus of elasticity.

NextEra evaluated these parametric reductions to determine the impact on the design basis of the Control Building. The licensee performed an operability determination and concluded the Control Building was within the limits of the design basis although with reduced NextEra continues to evaluate the extent of this condition.

NextEra's planned actions 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. Their proposal is described in their letter of April 14, 2011, in response to an NRC request for additional information B.2.1.31-1(ML11008A131). The proposal includes a"'-th- R " §.

Netr)analysic of the impact of ASR en the rurront licensinlg gfnd desjfignbs nldn h an extent of the condition assessment of ASR to support the Prompt ooerability determination, to be completed during June 2011.

CONTACT: Michael Modes, DRS (610)337-5198

J. Jolicoeur 2 With respect to Part 50 reouirements. Reaion I reviewed the NextEra current

%'V -- IL II--- -- - UII ended. TIam meant to address specific technical questions.

Com * [67": Please Include th licensee's detaied overall plan of action to systenalkc:aIy o ft 1e2 WM ot eaI nlanONKl( address the ASR degradation issue inb been workina closelv tooether to ensure entirety (Including process used. condition surwy, condition assessment (extent and charactertzalion including inaccesble -e Juno 2011. in a r.vi.w of the final analysis, 0egion I _n..reduud*-the assistance of NRR in that may be affected), root cause evaluation.

reviewing various Ng8E* documents/jteyatlg- to be issued from now until March 2012 determnation of structure severity rating (tentative) as noted in the licensee's position section below.1 .......................................... (including quafiftifed expenslon-to-dete and potential future.exansion end considering siru riumrcin class and exposure conditions)' structural evaluation and appraisal Licensee Positio. of degraded condition for design loads, end detenrmining remedial action/ condition management as appropriate) in the current NextEra has conducted a number of evaluations of OSR a*tfectee -*ira ns .arp...re operatig license period. The licensees actions centered around taking core samples of the concrete and conducti various tests fix of talcbig core samples and conducting selective tesls should be justified Into the contet f the bornpressve strerith and--------f-la-ticit ---------------- e h-epnmary overal plan. This plan should clealy bring out the licensee's philosophy and thinking for actions to date or planned are:

addressing to. ASR degradation issue, In s entirety, and how toe itemis Noted hinthe licensee

1. PFelimiR8FY Prompt Operability Determination for the Control Building (AR 581434 position fits ino the contet ofthe plan. The

a. ilb... y ..." weh'ff- based on compressive strength and modulus of lces's plan and evaluarion should factor In a quantitalve manner how the ability of the elasticity testing. Petrographic examination was also conducted confirming the presence ad structures to perform the Intended function and meet their design basis dill be of ASR in the core samples. Impacted Ifthe ASR degradation continues Into the future.

2. Design Change No. EC-272057, Concrete Modulus of Elasticity for the Control Building Electrical Tunnel and the Containment Enclosure Building (aVa'lableby Get,;N web.t. ,,

referring to AR Nos. 581434 and AR 1644074 which accepts the reduction in the modulus of elasticity in light of concrete core testing using a 10 CFR 50.59 screening I process.

3. Additional core semolina bn five other buildinas with less severe evidence of ASR -

Operability Determination will be available on or about June 30, 2011.

Isufficient, Vý ration, stiun 2-4. Enaineerina Evaluation scheduled for March 2012 which comoletes the aaino manaaement review and it is anticioated that it will not only address the oroposed agina L.muummu iuA.J;F suis is teiocn. mai oasis manaaement pro-ram for license renewal but also orovide recommended changes in the of this approeach? It appears that toe licensee's thinking Isthat toe entire ASIR Issue can be current Structures Monitorirm Proaram for all Maintenance Rule in-scoope buildino addressed by testing cores for compressive strength and modulus of elasticity mid that the affected by ASR. behaisvor of toe degraded concrete remrains unaffected as considered in the codes. The approach does not appear to address to. ASIR WhMin the limitations of hr testing. NextErs's Ino to date has not resulted in seismi categoEo I strucl. be*ng outside their design basis (control building and containme IComme degradation Issue inIts entirety (dNagnosi .~

Commieft (6123: Need to be specific.

(6.[13]: How about factors and considerations not covered by the testing (such as caus of the degiradation, degradation into toe future, sheer, eft)?

J.Jolicoeur 3 Region I Preliminary Inspector Views/Observations Commeat [614]: Ucensee needs to demonstrate the valtitY end submit to NRC.

Based on staff interactions to date related to this issue a number of questions have arisen: Comment [015]: Need to specific about the structure and foundation being referred to and their configuration end the conditon that is

1. Because the original design basis assumes no ASR is present during the design life of the being evaluated.

structure, it is not clear how ASR affects the original design assumptions or calculational Commentw [6151: For answers to thesse questions, the Region needs to consult NRC metods, such as the relationship between compressive strength and modulus of elasticity Inspection Manuel Pat 9900: Technilcal to shear capacity and shear-distribution of design forces used in the seismic analysis. For Guidance- Operabiy Determinations &

Functionality Assessments for Resolution of example the assumed relationship between compressive strength and-tensile strength, Degraded or Nonconforming Conditions shear strength, elastic modulus etc may not be valid with ASR present. We agree with Adverse to Quaitty or Safety. Suggest review headauarter staff who have raised a-auestions in this area hat remains unknown is how entire guidance and specific attention be dram much of an eft does the ASR have on this validity (somne resarc ma be ........ to Section 4.0 (Operability Detenmination Process) od Section C.13 (Speci*c Operebilty Issues - Stnuctursl Requlrements).

2. , preliminary analysis by NextEra focuses on the effect of ASR on the foundation's Commnsat [ANMt7:

response to design loads. It is not clear this approach, in the final analysis, would be Copy of uslevmt section of the ASTM 496 adequate. Should VRO&A 1 insist the final analysis include the response of the whole 10. Preemle"sd Dis building with ASR present in the foundation"! ............................................................ 10,1 Prociskl-An inter laboratory study of this test method has not been performed. Available research dat., however, suggests that the within batch

3. What is the extent, duration, and timing of actions that NextEra should take to address the cofficiedt of variation is 5 % (see Noas 4) for 6 3 problem of immediate operability, and maintenance of the design basis response?JfISoh[ 12-in. [150 3 300-mm] cylindrical specimens with words, how Iona do we wait and under what criteria do a have for research to be an average splitting tensile atrongth of 405 psi deel;e in ore to; adrs ke gusin eae to oprailt and copiac wft the (2.8 MPWa. Reasuts of two properly conducted tests on the same mateial, therefore, should not differ by more then 14 % (see N 4) oftheir average for splitting tensile strengths of about 400 psi [2.8 MPa].

4. Itshou ldi b Anoted that no tongil 610stregth tocitinilg is boing perG-fomed On tho conroto Acoro Also I do not understand relationship between rebar Sam.ples nd itis a. an is.sue

. aised by headqua.ters staff, With rospect to the question. o yield strensth and concrete shear/tensile strength as ton;Sile Steronth red-ucnt-io-n -inA cncRo~to, the inspectors View is that it i6-not FAelvan;t in a cn..trafinods*tu* r, ntlure aftor the ASR prE'ssuro lo1d i4 trAns . ,edto the r4b*Ar. USing the ASTM tRandard proposed by NRR, the toncale values reported can varYfrom tho real walu-e by up to +/-40% and, as. GAS .G..ch........ e. an harly beassumed to be a marial PFE)PerY,+/-P"4or to transfr, the presur contributin ao-'-arc to bF is .i...l.. on the order of less thain 9% of the robar yield based On cre~liminar'9 T~ i

5. A GorFe samrnple9 with ASR doeneFot r4oPre8sent the forcAs cOntaine~d in the sruc-tu-re boctau-se for: this test, in part*GU'aF, rebo-und -isnot considered and frictionsal ifuneinthe test itsel are noet a-ncoepmmdatod. As a mattzr of fact the fric-tional les-ses are-oxmaar-b-atod by the s laboratory practice of placing plywood on opposing faces of the tens-ile speo-,i-A

,tan-dard to SctO it ftrm roing off the test stand thus restraining axial oxeanRsin of the -6

6. Preliminarily the design change had a 50.59 review which screened out. In light of the newly discovered issue, one would think that. as a minimum, an evaluation would have been conducted in order to determine if there is

)mlment LAHtSZI: This wtole statement IS 1."Rar-rzo. Wthe splitting tel' IIIIIIdArd2I fromAAfracturoF moehanice point ef ~e??', G. Rece, G. V. Guineav j.PlanaS. and M. a" dundent and not relevant. Please delete it. I de.V-*.-d:, M.a.dri.d,sp ..... N._ ,

No..tcas testing to^ datehas n Or.iuted R' in SeiSmic category I "tru"tUr.. being outside their doiOAn baRns (conýtrol building and cnaptainment eanclosure buIldingý.-

J. Jolicoeur 4 Requested Actions In light of the questions above, Region I na-requests the assistance of NRR/DE in conjunction with the Division of License Renewal ind aD icable the Offl=f RPaeech n ......... mnt 102231:?

Ordr to evlut the beo Irsted Ae*W,, areas for the abv noe Netr opra*

be clal identified:

1. Adequacy of concrete core sampling (locations, numbers, frequency, fututr, etc).

2. Completeness of the laborty testing of core sampl InIudinga Daramreter obtained alona with laborator test gonditions for now and in the future.

3. Need for and pleteness of any insity 0*esting of building c e includira awroprdste paaetr obaie a1on with test codtin fo now anid In the fuum. As an exmmple. where and how much reber should be exxosd in order to assess the effect on rebar from fthASR issue.

4. Assess the effect of the alkali-silica reaction degradation on the current and future ability of safety structures to respond to design basis loads indina seismic response

5. Adequacy of an analysis of the foundations alone vs. the response of the whole structure when the foundation is degraded.

Formnatted:----------

Indent: Left: 0.5", Space After: 0 5-6. From the ana yi done aboe review ft ide*uacv of ft s ture mwoiorino pt, No bullets or numbering, AdJust space between Latin and Asian text, Adjust space prowta for necessary chmae in h1 of the AM Ise. between Asian text and numbers 6S. AF,., of .9 N ,x.. WNW p o .. d -- of t Go.....----rFormatted: Indent: Left: 0.5", No bullets or bInumbering 7- AMeqaw; of the Nte46rea finhi operability detininmetion wmplelied dwing june 204 1. - ---Formatted: Normal, Indent. Left. 0.25", No Ibullets or numbering In the longer term on or about March 2012, Region I needs the same assistance as noted above Oin ifltt [623]: Questions for NRR to when NextEra completes and Engineering Evaluation which s c t a addes s be s e i,,,wih reuwc to S for lice rnewal t mm an, are centd ad hd relate to ote) of wihrwc oc.

.sin rmt h tutrsmnioia.ormt mee th m inalac the overallaction plan toaddresste ~ASR rule ut)to* th ienewirt dataj be.. ,.lee.... n, ............ m uest NRR Issue.

welcosdee Suggest isaue dcmetdthe kIitaliene TIA based ato on a rview for aceu of th adiioa monitoring and mitcato sta is Prpoe W NextE!:@ pla an seifc ustonasdon inIlaht of the newly discovered ASR issue. [ - ----- --cunwttv documents of co=gm p avalbeo' eats ilbeaalbeI tha we h

ver now hiture Then, Issue -usqun separate lnAsor revsed 'nis with quesions to Coordination be addressed as more licensee evaluaionas we completed in the conte*i of the overali plan.

J. Jolicoeur 5 This request was discussed between Richard Conte (RI/DRS/EB1) and Meena Khanna (NRR/DE/EMCB) during a various conference calls on the subject of ASR at Seabrook. The TIA was accepted with an agreed upon response date within 90 0?ays after receipt ofthe ......

NextEra Engineering Evaluation completed during March 2012. Idays for final reapnse?

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Docket No. 50-443 ML111610530 SUNSI Review _ Complete DOCUMENT NAME: G:\DRS\Engineering Branch 1\-- MModes\TIA Seabrook ASR DTra,.docx Publicly Available Non-Publicly Available Sensitive Non-Sensitive To receivea copy of this omnt. Indicate In the concorrence boo C = Copy without atch/end E Copyith attactend N = No copy OFFICE RI IDRS RI DRS RI DRP RI DRS RI DRP NAME MModes RConte ABurritt PWilson DRoberts DATE 06/ /11 06/ /11 06/ /11 06/ /11 06/ /11 C 'OWf

S 2: 1] commn 1G11] Thomas 6128/20117:51:00 AM What is the technical basis of this approach? It appears that the licensee's thinking is that the entire ASR issue can be addressed by testing cores for compressive strength and modulus of elasticity and that the behavior of the degraded concrete remains unaffected as considered in the codes. The approach does not appear to address the ASR degradation issue in its entirety (diagnosis, prognosis, structural appraisal and evaluation, and mitigation/management). Has the licensee consulted specialist literature and personal in the area of ASR?

Suggest delete since this is speculative discussion. FYI - The conditions under which cracks form and propagate in concrete depend strongly on tension strength. Concrete tensile stresses also occur as a result of shear, torsion and other actions, and in most cases member behavior changes upon cracking.

Hence, it is important to be able to measure or predict with reasonable accuracy the tensile strength of concrete. It is important to realize that the real concern in shear analysis and design is with diagonal tension stress (areas of high shear in combination with flexure could fail suddenly by develoing diagonal cracks and therefore many ACI codes refer to shear as a measure of diagonal tension). Relationships in the ACI codes that are a function of sqrt(fc') are indeed a function of concrete tensile strength.