ML20197G195

Forwards Sser Re Resolution of Const Discrepancies in Concrete Structures,Identified by Const Appraisal Team.As- Built Category I Structures Meet Intent of FSAR Commitments & SRP Provisions.Issues Resolved

ML20197G195
Person / Time
Site:	Columbia
Issue date:	12/20/1983
From:	Knight J Office of Nuclear Reactor Regulation
To:	Novak T Office of Nuclear Reactor Regulation
References
CON-WNP-0715, CON-WNP-715 NUDOCS 8312290157
Download: ML20197G195 (8)

Text

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V4 v DEC 2 01E lECRA!;Duli FOR: Thomas F.,I;ovak, Assistant Director for Licensing Division of Licensing FR0ti: Jaues P. Knight, Assistant Director for Conponents and Structures Engineering Division of Engineering

SUBJECT:

SAFETY EV/LUATIOi: REPORT SUPPLEliEt:T WPPSS I;UCLEAR PROJECT li0. 2 - RESOLUTIO!;

0F C0!!STRUCTI0t; DISCREPAliCIES Ifi C0t: CRETE STRUCTURES Plant I;ano: UPPSS lluclear Projcct fic. 2 Docket fiumber: 50-397 Licensing Stage: OL Review Responsible Branch and Project !!anager: LB #2, R. Auluck The enclosed supplenent to the Safety Evaluation Report (SSER) is provided in response to a RV request for assistance to evaluate the adequacy of applicant's disposition of the construction discrepancics in some of the b!;P-2 concrete structures. The deficiencies were identified by an ILE Construction Appraisal Team (CAT).during its recent inspection of the plant. This evaluation is perforned by K. C. Leu of Section A of the Structural and Geotechnical Engineering Branch based on infornation provided by the CAT /ILE and the applicant.

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8312290157 831220 e ADOCK 05000397 James P. Knight, Assistant Director w for Components and Structures Engineering h Division of Engineering

Enclosure:

Safety Evaluation Report Supplement cc: R. Vollner D. Eisenhut T. Bishop, R-V J. Knight F. Iliraglia R. Dodds, R-V C. Lear A. Schwencer C. Tan J. Taylor IE K. Leu  !!. Kong, IE D. Jeng omeo .k.5..KjB , , , , , , , , , ,,,gSGE0E ,,DEjSGEB ,,DE,: AD/CSE

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Et!CLCSURE WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO. 2 DOCKET NO. 50-397 SAFETY EVALUATION REPORT SUPPLEMENT RESOLUTION OF CONSTRUCTION DISCREPANCIES IN CONCRETE STRUCTURES STRUCTURAL AND GEOTECHhlCAL ENGINEERING BRANCH

References:

1. "Ccnstruction Appraisal Inspection 50-397/83-29" from Richard C.

DeYoung to Washington Public Power Supply System, dated July 26, 1983.

2. " Response to Inspection Report 83-28, Notice of Violation Section "E" - Evaluation of Concrete and Reinforcing Steel" from C. S.

Carlisle to J. B. Martin dated September 16, 1983.

3. Task Interface Agreement Requesting Technical Assistance on CAT Findings dated October 19, 1983.

4. Meeting Between the Applicant and Its Consultants and NRC Staff in Bethesda, MD dated October 14, 1983.

5. Memo from C. S. Carlisle to J. B. Martin - Response to Requests Made at Ref. 4 dated October 31, 1983.

6. Ccnference Call Between the Applicant and SGEB Staff Clarifying Responses from Ref. 5 dated November 8, 1983.

7. Memo from G. C. Sorensen to A. Schwencer Re-submitting Responses to SGEB Staff dated Novenber 15, 1983.

1. BACKGROUf!D The above listed Reference 1 report issued by the CAT of the Office of Inspection and Enforcement (I&E) identified several construction program weaknesses. One of these weaknesses pertains to civil and structural construction aspects. The deficiencies related to the civil and struc-tural area identified by the CAT include: concrete reinforcement steel placement, rebar splicing and spacing, concrete mix and its qualitic,s, inspection records and disposition of nonconformance report (NCR), etc.

The CAT findings were based on information generated from ten out of twelve actually examined structural locations in the reactor building.

e In a Task Interface Agreement identified in Ref. 3, Region V requested NRR dssistance to perforn an evaluation of the validity of the appli-i cant's conclusions and the adequacy of the applicant's dispositions of l the above CAT idcr.tified deficiencies.

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1 l The Structural and Geotechnical Engineering Branch (SGEB) has provided the requested assistance and has performed the evaluation. The SGEB evaluation findings are discussed below.

2. KEY AREAS OF REVIEU AND DISCUSSIONS The applicant has selected a total of 17 members with 23 excavated locations for the purpose of evaluating the extent of the deficiencies identified by the CAT. The 23 locations include the 12 locations

! previously examined by the CAT. Twelve excavation samples were identi-

fied by CAT as having design specification deviations (See Table V-2 of l Ref. 1). The deviations include items such as rebar spacing, rebar

! alignment, missing rebar, concrete honeycombing and aggregate mix 4

change, etc. Each of the above deviations is reviewed and discussed as follows:

(1) Rebar Spacing Problem According to the CAT report, eight beams (Beams Nos. 2B11, 2B25, 2B5, 2B3, 3D18, 3B10, 4B30 and 6B9) and two reactor building mat locations

have rebar spacing and alignment problems which range from spacing problems between rebars, spacing problems between layers of rebars and the problems of rebar misalignments (bars 'in different layers not lined-up directly above one another). All of which deviated from ACI 318-71 code requirements.

) A. Discrepancy in In-Layer Rebar Spacing and Rebar Alignment' Between Layers

. In addressing the above described problems, the applicant responded (Refs 2, 4, 5 and 7) that:

a. ACI 318-71, Section 3.3.2 permits lesser spacing if, in the judgment of the engineer, workability and method of consolidation are such that the concrete can be placed without ,

honeycomb or void, 4

b. The UMP-2 investigation has found good bond between the concrete and reinforcing steel in all the sample excavations

. except for beams 2B11 and 2B25, which were further excavated to sound concrete part of the beams and appropriately repaired,

c. All the eight beams are shown to have sustained ccnstruction loads, which, in turn, were determined to be more severe than their corresponding operating loads, and

d. The 1960 ASCE paper No. 3047 titled " Concrete Beams and Columns with Cundled Reinforcement" provided test results indicating

! that no significant difference in behavior or ultimate strength l

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was found between bundled reinforcement case and the case of using spaced reinforcement.

We have reviewed the above -applicant's responses and other pertinent info rmation. We note that in. heavy-engineering construction such as the WilP-2 construction, heavy reinforcements are often required due to load requirements, thus, in many instances, causing rebars to be placed closer than the ccde limits. Under such conditions, however, the code allows some deviations in rebar spacing provided that the engineer /

constructor takes measures to assure that sound concrete consolidation is achieved. .

Based on the facts that it has been ccnfirmed by the applicant via field tests that the concrete consolidation was of good quality, that the beams possess large safety margins over their design loads and whenever needed, appropriate repair.of the excavated beams were done, and further-more, some related tests on bundled rebar applications showed no signifi-cantly detrimental effects upon, beam strength, we conclude that the applicant's response to and disp 6s'ition of the issue are acceptable and the issue is considered as resolved.

B. Discrepancy in Between-Layers Rebar Soacing The CAT report raised an issue on discrepancy pertaining to "Between-Layers Rebar Spacing." Beams 2B11, 2B25 arid 2B5 were reported to have rebar spacing deviations between layers of rebars.

We have reviewed the applicant's response to the issue (Ref. 2) and held a discussion with the applicant on December 16, 1983 to obtain additional information regarding rebar spacings applicable to the above identified beams. Based on the findings of our review and the additional information provided by the app'licant, and considering the fact that beams designed in accordance with the requirements of ACI 318-71 Code generally possess considerable safety margins, we conclude that the intent of the code requirement governing the "between layers rebar spacing" is met by beams 2B11, 2B25 and 285 and the issue is considered resolved.

(2). Concrete Honeycombing Problem Table V-2 of the Ref. 1 indicated deficient conditions related to concrete honeycomb (voids) for the following beams:

Beam 2B11: honeycomb visible and concentrated predominately between bars even where concrete below bar app 5ared sound Beam 2B25: same as beam 2B11 r Beam 2B3: honeycomb at the region of dowel lap splices was initially identified vi'a f;CR-1851. This area was re-repaired due to deficiencies related to the initial repair prior to the CAT inspection.

In Reference 7, the applicant pointed out that out of 23 excavated locations in 17 members, three bars (2B11, 2B25 and 283) had been

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identified as having severe congestion and honeycombing and voids during construction. It also indicated that the honeycombing associated with the three beams had been repaired in accordance with approved con-

, struction procedures. In addition, the beams had been re-analyzed i

taking into account the deficient conditions and were found to be

! structurally adequate to sustain their design loads and meeting perti-nent code allowables. This finding is acceptable to the staff for resolving the issue, i

(3) Missing Rebar Problem

] The CAT reported the missing of rebars at the following locations:

1 j Beam 2B5: Two of seven #11 bars missing from. bottom rebar layer Beam 2B11: One of eight dowels appeared to be missing in first layer; stirrups have inadequate cover; also a discrepancy on the 5

size and spacing of stirrups.

l Beam 3B18: One of eight dowels not located.

I j In his effort to justify the design acceptability of the beams with the above noted deficiencies, the applicant provided the following justifi-

cations

j A. With respect to Beam 285, its original design called for two rows

of seven #11 bars. However, the as-built showed five bars in 1 bottcm most layer, five in the middle and four in the top layer i providing the required amount of rebars.

B. With respect to Beam 2B11, the dowel which appeared to be missing i during CAT inspection has been found after further excavation; as to the question of not providing adequate concrete cover to the stirrups, the applicant committed to provide adequate concrete i cover over the stirrups during patching work. As to the question i on the size and spacing of stirrups, a checked and approved j original calculation sheet, not previously viewed by the CAT, shews

that both the size and spacing of stirrups for Beam 2811 agree with

those shown on the design drawing.

i C. With respect to the missing dowel of Beam 3B18, a re-evaluation of

, the beam with the missing dowel was carried out and the beam was j shown to have adequate capacity for its design loads.

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{ Based on review of the above information, we conclude that the

! justifications provided by the applicant in resolving the issues are l reasonable and acceptable.

(4) The issue of Horizontal Lapping Vs. Vertical Laccing P

- The CAT report also identified as a discrepancy, the reinforcement lapped hori:ontally contrary to the required vertical lappings applica-ble to beams 2B11, 2B25 and 3B18.

The applicant responded that the orientation of lap splices was not defined on the shop drawing, therefore, lap splices can be placed in either plane and the item should not be treated as a discrepancy.

Since there is no clear cut code requirement governing the orientation of lap splices, we conclude that the particular lap splice orientation adopted is not a deficiency and should be acceptable.

(5) Concrete Mix Change The CAT report raised a concern pertaining to the fact that 1-1/2" aggregate concrete was substituted for 3/4" aggregate concrete for beam 4B30 and beam 689 without a "P.equest for Information (RFI)." In an effort to justify the concrete mix change, the applicant stated that:

A. the mix substitute from 4SA-P (3/4" aggregate) to 4MA-P (1-1/2" aggregate) was approved by the Burns and Roe field engineer prior to concrete placement, B. both classes of concrete have the same required minimum 28-day strength of fc' = 4000 psi, and C. the concrete bond and consolidation in these two beams was de-termined as excellent, therefore, the mix change adopted should not affect the structural integrity or capacity and should be accept-able to the staff.

We consider the applicant's justification adequate and acceptable.

(6) Documentation Review and Disposition of NCR and RFI .

In the CAT report, deviations of the documentation of the as-built structural elements from the design / construction specifications were noted. It also identified deficiencies in dispositions of NCR pertain-ing to beams 2811, 2B3 and 2B25.

In addressing the above deficiencies, the applicant provided the pro-cedures adopted for evaluation of the 23 locations in 17 members (Ref.

2) which included the following items:

A. The design drawings on each member were checked against the design calculations.

B. The shop drawings were checked against the design drawings.

C. The excavated areas shown on the as-built drawings were checked against the shop drawings.

i D. The structural capacity was checked against the structural design j loads. Beans 2B5 and 2B11 were checked in detail.

E. The pour records were reviewed for RFIs and NCRs. The applicant also stated that some of the NCRs and RFIs were found deficient in that the deviations in the as-built members such as rebar spacing, concrete voids, mix change and patching, etc., were not properly identified. However, the results of the re-analysis and re-evaluation indicated that all the as-built structural members are found to be structurally adequate for their specified loads and 4

corrective actions have been taken on Beams 2B3, 2B11 and 2B25, where the patching of concrete voids was implemented in accordance with approved construction procedures. Therefore, the above noted

deficiencies should be accepted as resolved.

We have reviewed the applicant's justifications and conclude that the above deficiencies with the stated corrective actions implemented are j resolved, i 3. Selection of Samples

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In the course of our review, the staff raised a concern about how l

3 representative and conservative are the selected excavation samples in determining the overall concrete construction adequacy at WNP-2. The applicant responded to the staff concern with the following:

, (1) Beams selected at EL. 471 in the reactor building include four beams (2B3, 285, 2B11 and 2B25) out of 35 beams that have two or more layers of reinforcement at the bottom. These are the loca-tions with heavy rebars and dowels that lack of concrete consoli-

dation, if any, would be most likely to occur. To diversify

sampling pattern, four other beams at different locations, and samples at west and east external walls, pilaster / column, north wall of separation pool, fuel pool wall, foundation nat and slab were taken to make a total of 17 members with 23 locations samples.

! (2) An evaluation summary table was made of the 17 members in terms of i design margin. The table showed that the desi 1.0 to 5.6 for moments (positive and negative)gn and margins 1.1 to 2.2range for from

shear with 1.0 being the design margin complying with ACI 318-71 code re,quirements and licensing commitments.

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! (3) The sample selection was not based on a random nor a statistical

! approach. Rather, it was based on a conservative one. The 17 l

members selected are believed to be the ones most likely to exhibit i

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misplaced bars and honeycombing because of heavy rebar requirenent.

Thus the scopies are purposefully selected to be on the conserva-tive side and, therefore, should be acceptable to the staff.

We have evaluated the applicant's iustification and rationale for sampling and conclude that the sampling approach used is acceptable.

4. Conclusion The discrepancies outlined in the CAT report (Ref. 1), the responses provided by the applicant (Ref. 2.5.7) including the discussions held between the staff and the applicant (Refs. 4 and 6) pertaining to the concrete construction prcblems at WNP-2, have been reviewed. Based on the discussions provided above in this SSER, we conclude that the as-built Category I structures at WNP-2 have met the intent of WGP-2 FSAR commitments and the applicable SRP provisions,.thus, the issues raised by CAT /I&E are considered resolved.

Docket No.: 50-397 MEMORAf100M FOR: H. R. Denton, NRR E. G. Case, NRR J. Carter, NRR D. G. Eisenhut, DL R. A. Purple, DL H. Thompson, DHFS R. Vollmer, DE R. Mattson, DSI T. Speis, DST J. Sniezek, IE G. Holahan, ORAB T. Novak, DL F. Miraglia, DL THRU: A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing FR0f t: R. Auluck, Project Manager Licensing Branch No. 2 Division of Licensing

SUBJECT:

DAILY HIGHLIGHT - WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT N0. 2 On December 20, 1983, an operating license was issued to Washington Public Power Supply System for Nuclear Project flo. 2, at reactor core power levels not in excess of 3323 megawatts thermal (100% power). Pending Commission's approval, operation is restricted to power levels not to exceed 5% of full power.

R. Auluck, Project Manager

- Licensing Branch No. 2 Division of Licensing DL:LBA2/PM DL:LB#2/BC DISTRIBUTION:

RAtt+uck : pt ASchwencer I2/p/83 12/jv/83 NRC PDR LB#2 Rdg.

EHylton RAuluck ASchwencer I!DkN OCM O 00 7 p PDR

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