ML12173A462
| ML12173A462 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 06/04/2012 |
| From: | Roberts D J Division Reactor Projects I |
| To: | Jolicoeur J R Licensing Processes Branch (DPR) |
| References | |
| FOIA/PA-2012-0119 | |
| Download: ML12173A462 (6) | |
Text
N(KR R, 0r-z MEMORANDUM TO: UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 475 Allendale Road King of Prussia, PA 19406 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 Control Building as part of their materiai condition assessment fcon-crete -stru-tures -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 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(ML1 1008A131).
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 commet [2]: Pleas. inciud. a stslterentof]
how the de~grade condition was first lenffijdto' and what led to the core sampiea being Wo~n, J. Jolicoeur 2 With respect to Part 50 reouirements.
Reaion I reviewed the NextEra current o ft 1e2 WM ot eaI nlanONKl(been workina closelv tooether to ensure Juno 2011. in a r.vi.w of the final analysis, 0egion I _n..reduud*-the assistance of NRR in reviewing various documents/jteyatlg-to be issued from now until March 2012 (tentative) as noted in the licensee's position section below.1 ..........................................
Licensee Positio.NextEra has conducted a number of evaluations of OSR ns .arp...re centered around taking core samples of the concrete and conducti various tests fix bornpressve strerith and--------f-la-ticit
e --- h-epnmary actions to date or planned are: 1. PFelimiR8FY Prompt Operability Determination for the Control Building (AR 581434 a. ilb... y ..." weh'ff- based on compressive strength and modulus of elasticity testing. Petrographic examination was also conducted confirming the presence of ASR in the core samples.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 process.3. Additional core semolina bn five other buildinas with less severe evidence of ASR -%'V -- IL I I--- -- -UII ended. TIam meant to address specific technical questions.
Com * [67": Please Include th licensee's detaied overall plan of action to systenalkc:aIy address the ASR degradation issue in b entirety (Including process used. condition surwy, condition assessment (extent and charactertzalion including inaccesble -e that may be affected), root cause evaluation.
determnation of structure severity rating (including quafiftifed expenslon-to-dete and potential future.exansion end considering siru rium rcin class and exposure conditions)'
structural evaluation and appraisal of degraded condition for design loads, end detenrmining remedial action/ condition management as appropriate) in the current operatig license period. The licensees actions of talcbig core samples and conducting selective tesls should be justified Into the contet f the overal plan. This plan should clealy bring out the licensee's philosophy and thinking for addressing to. ASR degradation issue, In s entirety, and how toe itemis Noted hin the licensee position fits ino the contet ofthe plan. The lces's plan and evaluarion should factor In a quantitalve manner how the ability of the ad structures to perform the Intended function and meet their design basis dill be Impacted If the ASR degradation continues Into the future.I I sufficient, Výration, stiun Operability Determination will be available on or about June 30, 2011.2-4. 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 manaaement pro-ram for license renewal but also orovide recommended changes in the current Structures Monitorirm Proaram for all Maintenance Rule in-scoope buildino affected by ASR.WhMin the limitations of hr testing. NextErs's Ino to date has not resulted in seismi categoEo I strucl. outside their design basis (control building and containme L.muummu iuA.J;F suis is teiocn. mai oasis of this approeach?
It appears that toe licensee's thinking Is that toe entire ASIR Issue can be addressed by testing cores for compressive strength and modulus of elasticity mid that the behaisvor of toe degraded concrete remrains unaffected as considered in the codes. The approach does not appear to address to. ASIR degradation Issue in Its entirety (dNagnosi
.~Commieft (6123: Need to be specific.ICommen (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 Based on staff interactions to date related to this issue a number of questions have arisen: 1. Because the original design basis assumes no ASR is present during the design life of the structure, it is not clear how ASR affects the original design assumptions or calculational metods, such as the relationship between compressive strength and modulus of elasticity to shear capacity and shear-distribution of design forces used in the seismic analysis.
For example the assumed relationship between compressive strength and-tensile strength, shear strength, elastic modulus etc may not be valid with ASR present. We agree with headauarter staff who have raised a-auestions in this area hat remains unknown is how much of an eft does the ASR have on this validity (somne resarc ma be ........2. , preliminary analysis by NextEra focuses on the effect of ASR on the foundation's response to design loads. It is not clear this approach, in the final analysis, would be adequate.
Should VRO&A 1 insist the final analysis include the response of the whole building with ASR present in the foundation"!
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- 3. What is the extent, duration, and timing of actions that NextEra should take to address the problem of immediate operability, and maintenance of the design basis response?JfISoh[
Commeat [614]: Ucensee needs to demonstrate the valtitY end submit to NRC.Comment [015]: Need to specific about the structure and foundation being referred to and their configuration end the conditon that is being evaluated.
Commentw [6151: For answers to thesse questions, the Region needs to consult NRC Inspection Manuel Pat 9900: Technilcal Guidance-Operabiy Determinations
&Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quaitty or Safety. Suggest review entire guidance and specific attention be dram to Section 4.0 (Operability Detenmination Process) od Section C.13 Operebilty Issues -Stnuctursl Requlrements).
Commnsat [ANMt7: Copy of uslevmt section of the ASTM 496 10. Preemle" sd Dis 10,1 Prociskl-An inter laboratory study of this test method has not been performed.
Available research dat., however, suggests that the within batch cofficiedt of variation is 5 % (see Noas 4) for 6 3 12-in. [150 3 300-mm] cylindrical specimens with an average splitting tensile atrongth of 405 psi (2.8 MPWa. Reasuts of two properly conducted tests on the same mateial, therefore, should not differ by more then 14 % (see N 4) of their average for splitting tensile strengths of about 400 psi [2.8 MPa].4.words, how Iona do we wait and under what criteria do a have for research to be deel;e in ore to; adrs ke gusin eae to oprailt and copiac wft the It shou ldi b Anoted that no tongil 610stregth tocitinilg is boing perG-fomed On tho conroto Acoro Sam.ples nd itis a. .an is.sue aised by headqua.ters staff, With rospect to the question.
o ton;Sile Steronth red-ucnt-io-n -inA cncRo~to, the inspectors View is that it i6- not FAelvan;t in a r, ntl ure aftor the ASR prE'ssuro lo1d i4 .trAns ,ed to the USing the ASTM tRandard proposed by NRR, the toncale values reported can varYfrom tho real walu-e by up to +/-40% and, as GAS .e. .G..ch........
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 A GorFe samrnple 9 with A SR doe ne Fot r4oPre8sent the forcAs cOntaine~d in the sruc- tu -re boctau- se for: this test, in part*GU'aF, rebo-und -is not 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 ,tan-dard laboratory practice of placing plywood on opposing faces of the tens-ile speo-,i-A to SctO it ftrm roing off the test stand thus restraining axial oxeanRsin of the -6 Also I do not understand relationship between rebar yield strensth and concrete shear/tensile strength as 5.6. 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 dundent and not relevant.
Please delete it. I 1 ."Rar-rzo.
W the splitting tel' IIIIIIdArd2I fromA A fracturoF moehanice point ef ~e??', G. Rece, G. V. Guineav j.PlanaS.
and M. a" de M.a.dri.d, sp ..... N._ , No..tcas testing to^ datehas n O R' r.iuted in SeiSmic category I "tru"tUr..
being outside their doiOAn baRns (conýtrol building and cnaptainment eanclosu re 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 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 fth ASR 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 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. rmt h .sin tutrsmnioia.ormt mee th m inalac the overallaction plan toaddresste
~ASR Issue. Suggest isaue the kIital TIA based on a rule th ienewirt dataj be.. ,.lee ....n , m ............
uest NRR welcosdee dcmetd iene ato rview for aceu of th adiioa monitoring and mitcato sta is Prpoe W NextE!:@ pla an seifc ustonasdon in Ilaht of the newly discovered ASR issue. [ documents of co=gm p eats tha we----- --- cunwttv avalbeo' ilbeaalbeI h Coordination ver now hiture Then, Issue -usqun separate lnAs or revsed 'nis with quesions to be addressed as more licensee evaluaionas we completed in the 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.hR e fe re n c e .....................................................http://portal, nrc.-qov/edo/ri/EBl1/Shared%/20Documents/Forms/AlIItems.aspx
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I I days for final reapnse?l comnent [G65]; Refemne. should be/pft and eicydy W , &lughthey may be l and accesedl fom the webelte.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 receive a copy of this omnt. Indicate In the concorrence boo C = Copy without atch/end E Cop yith 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.