ML12173A463
| ML12173A463 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 06/04/2012 |
| From: | Darrell Roberts Division Reactor Projects I |
| To: | Nelson R Division of Policy and Rulemaking |
| References | |
| FOIA/PA-2012-0119 | |
| Download: ML12173A463 (6) | |
Text
- J 0'ftRl(,ý UNITED STATES 0P NUCLEAR REGULATORY COMMISSION REGION I 475 Allendale Road King of Prussia, PA 19406 C- ,II IX.",
I MEMORANDUM TO: CelhR-JeWinee Robert A. Nelson, 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 consequence of alkali-silica reaction (ASR) degradation of safety related concrete structures at Seabrook Station, and to evaluate the impact of the degradation on the current licensing and design basis.
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, testsT undertaken as a part of the core sample analysis, reported a change in material properties. The analysis reported the presence of .lkaliWili r*ea*c;t9.io (ASR) in core samples taken from chronically wet walls below grade, with apparent reductions reported 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 that the Control Building was within the limits of the design basis although with reduced margins. 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 theiW-a letter of-dated April 14, 2011, ia-under the response to a.;-NRC request for additional information B.2.1.31-1_(Aaencvwide Documents Access and Management System (ADAMS) Accession No. ML11 1008A131). The proposal includes another analysis (termed "final" by NextEra)- a~alýyei-of the impact of ASR on the current licensing and design basis, including the extent of the condition, to be completed during June 2011.
CONTACT: Michael Modes, DRS (61 0)_337-5198
I J-JoieewR. Nelson 2 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 lnspssction Report 05000443/2011002 (mIADAMS Accession No. ML111330689). More details related to the newly discovered ASR issue ieare also documented in NRC Inspection Report N"*-05000443/2011007 (mnADAMS Accession No. MLI 11360432). which was issued as-a part of the-alicense renewal inspection-feWt. The cover letter for this-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 License Renewal) have been working closely together to ensure the agency reviews this matter in unison.
Region I nedse recuests the assistance of NRR in reviewing various NextEra Formatted: Plain Text, Space After: 0 Pt, documents/evaluations that have already been completed, and NRR assistance will also be /Adjust space between Latin and Asian text, Adjust space between Asian text and numbers requested in the future to review documents/evaluations that NextEra plans to issue te-be icued femo etmween now uWtil-and March 2012 (tentative, Ia) as they become available.
Therefore. Region I expects that this TIA reauest will be the first in a series of TIA reauests related to ASR degradation at Seabrook. -Both the completed and planned documents/evaluations are as follows:
as noted in the Iicancee'e pocitionA GGction- boloVW. %
- Formatted: Plain Text, Space After: 0 pt, Adjust space between Latin and Asian text, Adjust space between Asian text and numbers centered aroun-d taking core samples of the Ge nc.ete and conducting variouR teISt for comproessive' ctronth and mod-ul-un -ofoelaticity on these unconfined samples. Thoe primarcy actione to date Or plann~ed are:
A. Prompt Operability Determination for the Control Building (6R.1434 available by certrec" website) based on compressive strength and modulus of elasticity testing.
Petrographic examination was also conducted confirming the presence of ASR in the {Formatted: Font: Arial, 11 ptI Formatted: Font: Arial, 11 pt core samples. (Completed on XX/XX/XXXX)
B. Design Change No. EC-272057, Concrete Modulus of Elasticity for the Control Building Electrical Tunnel and the Containment Enclosure Building (available by certregx website), 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. (Completed on XX/XX/XXXX)
C.~
buildings with les severe evidenoe of ASR, -
Oprbf emAe N!b w~b~2GHo or about June 30, 20l1%-----
DQ.Engineering Evaluation echoduld-Wedd for March 2012 which completes the aging management review and it-is anticipated that it will not a..lo address the proposed aging management program for license renewal but-and also provide recommended changes in the current Structures Monitoring Program for all Maintenance Rule in-scope buildings affected by ASR. (Scheduled for March 2012)
I J. eli ur. Nelson3 3 D. Formatted: Ust Paragraph, Numbered +
Level: 1 + Numbering Style: A, B, C, .. + Start at: 1 + Alignment: Left + Aligned at: 0.25" +
Within the limitations of their testing, NextEra has determined that 's testing to date has n Indent at: 0.5" eeulted-itpnone of the seismic category I structures tested to date (the control building and containment encZosure building) have been found to be beVg-outside their design basis (GontpeI building and c-on taiandt aconusin building).
~ ~~
The~~~ ad--..--aest~ Sebro wih h icneehs ...--ae hsedtemn.in aQ hv~ddiJ2ILLLtd "i -- - -. A Region 1Preliminar~y inqspotor M'i~aQew/bPg.Fationsr Based on the review of the ASR issue to date. the Reaion I staff believes that NRR should also consider the followina information durina this TIA review.
.__Because the original design basis assumes no ASR is present during the design life of the -" Formatted: Bulleted + Level: 1 + Aligned at:
structure, it is not clear how ASR affects the original design assumptions or calculational 0" + Indent at: 0.25" methods, such as the relationship between compressive strength and modulus of elasticity to shear capacity and shear force used in the seismic analysis. For example, the assumed relationship between compressive strength and tensile strength may not be valid with ASR present.
- ~':e agree ::itn noao~uarter starr* wno LJ nay*L ra:soa A*
aLquestions in mis area. ~':nat Formatted: Indent: Left: 0.5", No bullets or rem~aIns UnRKRxn IS now"mucnR o an efffct ooos0- the ASR ha'e On mAis VoRiY ý reerhmay be needed)-
4(-
- Formatted: Indent: Left: -0.25" 0-It Ahould be noted that noNo tensile strength testing is being performed on the concrete core samples and it is an issue raised by hcadeu*'*"*s -f. thr, respect to the queSion o ten *S.r*ongthreduction in Gn...., the nsspo.tr' -cv However. the ReMion I staff believe that tensile strenth #t-isnot relevant in a constrained structure after the ASR pressure load is transferred to the rebar. Using the-ASTM XXXX sadard.propocod by-NRR, the reportetensile values fepoead-can vary from the-real values by up to +40%
and, as one researcher said, '!-._-,.-can hardly be assumed to be a material property".._"
Prior to transfer, the pressure contribution appears to be minimal (on the order of less than 5% of the rebar yield based on preliminary research of literature). Formatted 5 Normal
I j. el xaRN&I~n4 4 A core sample with ASR does not represent the forces contained in the structure because for this WK in p*aricular, rebound is not considered and frictional influences in the test itself -- j comn"M EBWH61: Mých tw -i are not accommodated.m a a matt' r of fac ,,-h,%The frictional losses are exacerbated by the standard laboratory practice of placing plywood on opposing faces of the tensile specimen to stop it from rolling off the test stand, thus restraining axial expansion of the sample.
1."Review of the splitting-test standards from a fracture mechanics point of view", C. Rocco, G. V. Guinea, J. Planas, and M.eN:=
Facultad de Ingenleria, Universidad Nacional de Ia Plata, La Plata, Argentina, Departamento de Ciencia de Materiales, Universidad Politdcnica de Madrid, Madrid, Spain, 5 September 2000 Requested Actions
'n light Gf the.u.et. .. abo'.... Region I noods-rguests the assistance of NRRA)K-iR orde* itd--f olwing
- )nealaieteblo documents to determine if they provide Vmub amaolunidjiven the concrete dearad ton identified due to ASR. Where aDolicable, Region I requests that NRR identify where regulatory (3 % pW Ipobesur o requirements may not have been met \\hMkwn loeslow fte ge A. Prompt Operability Determination for the Control Building.
(Completed on XX/XX/XXXX)
B. Desian Chanae No. EC-272057. Concrete Modulus of Elasticity for the Control Building Electrical Tunnel and the Containment Enclosure Building.
(Completed on XX/XX/XXXX) the-abo".'o noted Next~ra operability dotermninatb~n and design changes or ether; o'galua'tioce thAt may suooort thoc es.e~ Fe6c--s uch arc detaied cAlculotiorWz Or GGmP6tor coda vork. IfNRR Fomtheqod: er:t Paragrph NumEI0,rev I finds that either or both of the above documents do not provide reasonable assurance of continued operability, Region I reauests that NRR identify the basis of their concerns.
Soecificallv Reajon I reauests that NRR identify any ci~ncems with the aRsumntinn~ Inhweutat: 9cAl revewma methodoloaies, or calculations. etc.. related to items I through 6 below for each of the documents listed above. For oAch Of *ho rea.",our regu'atory basis hehuld be Glearl' identified:
- 1. Adequacy of concrete core sampling (locations, numbers, frequency of sampling in the future, etc).
- 2. Completeness of the laboratory testing of core sampling including appropriate parameters obtained along with laboratory test conditions for now and in the futre. Formatted: List Paragraph Formatted: Ust Paragraph, Numbered +
- 3. Need for and completeness of anyjnitu testngfbudng conditions -including_ Level: 1+ Numbering Style: A, , C,... + Star appropriate parameters obtained along with test conditions for now and in the future. As Indent at: 0.5"
'(Formatted:uFont:Italic
I J la'eaeee*R. Nelson 5 an example, where and how much rebar should be exposed in order to assess the effect on rebar from the ASR issue.
- 4. Assessment of the effect of the alkali-silica reaction degradation on the current and future ability of safety structures to respond to design basis loads, including seismic rezPonceevents.
- 5. Adequacy of a-the analysis of the foundations alone vs. the response of the-a whole structure when the foundation is degraded.
G. Frm analysis
,tho d... ablv'e, .. i:the of t uo proga %F.asom"r.qoin19 A~mth S su1-------
- 4. Formatted: Numbered + Level: 1 +
Numbering Style: 1, 2, 3, ... + Start at: 1 +
Alignment: Left + Aligned at: 0.25" + Indent at: 0.5" Formatted: Space After: 0 pt, Adjust space between Latin and Asian text, Adjust space A lan. kh'a Lftnagir to=
Vm between Asian text and numbers noted aboya when Ne&ttEra complotoc and Engineering Evaluation vhich should Formatted: List Paragraph, Indent: Left: 0",
complete tho aging mnanagement rov1ew for liconcois ironowMal but more importantly, Space After: 0 pt, Adjust space between Latin and Asian text, Adjust space between Asian text rocoMmonRdationeA arO_ rczpec~t to Ghanges to the existing sttrusturcc vniiatdwth and numbers 1A1_.
Formatted: List Paragraph, Numbered +
requcat NRR Feoviow for: adequary of the additional monRitoring and m~itigation etratogico, Level: 1 + Numbering Style: 1, 2, 3, ... + Start at: 1 + Alignment: Left + Aligned at: 0.25" +
proposed by NedEra in; light of #;e n 'y di"e"..ered. ASR u..... Indent at: 0.5" Coordination This request was discussed between Richard Conte and Michael Modes (RI.IRS,61-), and Meena Khanna. Geome Thomas. and Barry Miller (NRRADEAEMGB) during a w ,ie -s conference calls on 6/17/2011 the su4sjet of*A.fS. at Sabro.o'. The TIA was accepted with an agreed upon response date within 90-X days after receipt, of the Ne)'dEa Engineering Eralusation cmomleted during March 2012.
References htto://oortal.nrc.gov/edo/ri/EBl /Shared%/20Documents/Forms/Allltems.aspx Docket No. 50-443
0.
I I Whome R. Nelson 6 ML111610530 SUNSI Review _ Complete DOCUMENT NAME: G:\DRS\Engineering Branch 1\- MModes\TIA SeabrookASR Dra docx Publicly Available Non-Publicly Available Sensitive Non-Sensitive f I)
To receive a copy of this docnent. indicate in the concurrence box C = CO w~thout attachlend; Copy vith attactrrndW N = No copy OFFICE RI DRS RI DRS RI DRP RI DRS RI DRP NAME MModes tRConte ABurritt j PWilson DRoberts DATE 06/ /11 06/ /11 06/ /11 06/ /11 06/ /11 1 FI CGR OPý-