ML17296B003

Interim Deficiency Rept Re Inadequate Concrete Strength Achieved W/Pneumatically Placed Mortar Repairs.Evaluation of All Repairs Will Be Completed 801201.Final Rept Will Be Submitted by 801215

ML17296B003
Person / Time
Site:	Palo Verde
Issue date:	10/07/1980
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Spencer G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
10CFR-050.55E, 10CFR-50.55E, ANPP-16500-BSK, NUDOCS 8010160539
Download: ML17296B003 (16)

Text

REGULA Y INFORMATION DISTRIBUTIO SYSTEM (RIDS)

ACCESSION NBR: 8010160539 DOC DATE: 80/10/07 NOTARIZED: NO DO ii

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FACIL:STN 50-528 Palo Verde Nuclear Stationi Unit Arizona Publi 500052 STN-50-529 Palo Verde Nuclear Stationi Unit 2i Arizona Publi 0500 AUTH INANE AUTHOR AFFILIATION VAN BRUNTPE ~ ED Arizona Publ,ic Service Co.

RECIPR NAME RECIPIENT AFFILIATION SPENCERiG ~ ST Region 5i San Francisco'eactor Construction L Engineer

SUBJECT:

Inter'im deficiency rept re inadequate concrete strength achieved w/pneumatica,lly placed'ortar repa.irs.Evaluatiogl of al,l repairs will be completed 801201 ~ Fina,l>> rept will be submi t ted by 801215 ~

DISTRIBUTION CODE: S019S COPIES RECEIVED:LTR TITLE: Construction Deficiency Report (10CFR50 ~ 55E)

L ENCL L SIZE:

NOTES:Standard di zed Plant ~, 05000528 Standardized Plant. 05000529 RECIPIENT COPIES RECIPIENT'D COPIES ID CODE/NAME LiTTR ENCL CODE/NAME LTTR ENCL ACTION9 A/D LICENSNG 00 1 1 MIRAGLI A z F ~ 05 1 1 LEE,J ~ "

06 1 1 KERRIGANg J ~, 07 1 1 INTERNAL: AD/RC I/IE. 17 1 1, AEOD 18 1 1 ASLBP/J;HARD. 1. D/DIR HUM FAC15 1 1 EDO 8 STAFF" 19 1 . 1 EQUIP. QUAL'. BR11 1 HYD/GEO BR 22 1 ILEI 09 LIC QUAL BR 12 1 1 MPA 20 1 1 NRC- PDR 02 OELD 21 1 1

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PRO T REV 13 1, 1 QA BR 10 1 1 G F 01 1 1 RUTHERFORDiW ~ IE" 1 1 ST S DE.V 21 1 1 EXTERNAL: ACRS,

'NS I C1" 08'6 16 1

LPDR 03 1 1 OCT 17 1960 TOTAL; NUMBER OF COPIES REQUIRED: LTTR '9 ENCL 39

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ARIZORA IIUCLIl POWER PROJECT Post Office Box 2166o Phoenix, Arizona 85036 9-o",~<

October 7, 1980 ANPP-16500-BSK/JAR U. S. Nuclear Regulatory Commission Region V Walnut Creek Plaza Suite 202 1990 North California Boulevard Walnut Creek, California 94596 Attention: Mr. G. S. Spencer, Chief Reactor Construction and Engineering Support Branch

Subject:

A 50.55(e) Reportable Deficiency Relating to Inadequate Concrete Strength Achiev'ed with Pneumatically Placed Mortar Repairs Interim Report Pile: 80-019-026

Reference:

Telephone Conversation between J. Eckhardt'and J. E. Cook on September 4, 1980 (DER 79-12)

Dear Sir:

The NRC was notified of a reportable deficiency in the referenced telephone conversation. At that time, it was estimated that a final report would be available within thirty (30) days.

Due to the extensive investigation and evaluation required, an interim report is attached. It is now expected that this information will be finalized by December 15, 1980, at which time a complete report will be submitted.

Very truly yours,r E. E. Van Brunt, Jr.

APS Vice President Nuclear Projects ANPP Project Director EEVBJr/BSK:skc V Attachment 80ro ~60 539

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U. S. Nuclear Regulatory Commission Attention: Mr. G. S. Spencer, Chief Page 2 cc: /Victor Stello, Jr., Director Office of nspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 A. C. Gehr Snell & Wilmer R. L. Robb D. B. Fasnacht W. E. Ide J. H. Allen A. C. Rogers J. A. Brand W. H. Wilson W. G. Bingham W. J. Stubblefield J. E. Bashore R. H. Grant R. W. Welcher D. R. Hawkinson

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INTERIM REPORT REPORTABLE DEFICIENCY ARIZONA PUBLIC SERVICE COMPANY (APS)

PVNGS UNITS //1 AND //2 I. Potential Problem The pneumatically placed mortar method of concrete imperfection repair was introduced to the PVNGS jobsite about August, 1978.

The first indication of a problem with pneumatically placed mortar was identified in September of 1979 when NCR C-J-1542 was generated. The NCR identified a number of concrete imper-fections in the Control Building of Unit f12. The disposition of the NCR made in October, 1979 was "Repair" in accordance with Section 16 of Specification 13-CM-365 (Installation Specification for Forming, Placing, Finishirig and Curing of Concrete). During the repair of these imperfections, appli-cation problems were found in the use of pneumatically placed mortar. In-situ concrete testing indicated a need for more accurate analysis by core sampling. Core samples were obtained from repaired locations and tested. Results indicated that pneumatically placed mortar was insufficient in strength from all sample areas. These results indicate that there may be a generic concern in strength adequacy of previous applications of pneumatically placed mortar.

Initial evaluation of this problem was limited to pneumatically placed mortar and concerned mainly surface imperfections which did not appear to adversely affect the safety performance of the structures. However, further investigation described below, revealed "a much more extensive problem that could present a safety hazard.

II. A roach To and Status Of Pro osed Resolution A plan titled "Evaluation and Disposition of Concrete Repair's for DER 79-12" (attached) was developed in April, 1980. This plan provides instructions for the ultimate resolution of this subject by providing a full-scale evaluation, consisting of in-situ testing and a walk-down of all accessible areas of all buildings in Units 81 and //2, to locate all areas of repaired concrete imperfections because the concrete pour records did not indicate the exact .location of the surface repairs. Evalu-ation of each repair consists of visual examination and tapping on repaired areas, and core samples taken of the visually accepted patches to determine the quality of the concrete.

During the evaluation, it became apparent that concrete imper-fections that had been repaired by pneumatic placement could not Be visually distinguished from those repaired by mortar replacement or drypacking. All concrete imperfection areas were, therefore, evaluated and it was determined that not only pneumatically placed repairs were suspect, but all other repair methods were suspect also. NCE's C-X-1897 and C-X-1925 written so as to include all concrete imperfection repairwere areas.

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Interim Report Page 2 To date, the results of this evaluation indicate that concrete repairs were unacceptable using pneumatic placement, mortar replacement, and drypacking methods. If left uncorrected, these unacceptable repairs could possibly cause excessive stress to develop during a seismic event in the various shear walls.

Use of pneumatically placed mortar as a method of repair has been discontinued as of November 9, 1979. Specification,13-CH-365, Section 16.0 (Concrete Repair) has been revised to better control both the methods and materials used in the repair of concrete imperfections. Methods and materials have been consolidated to avoid confusion and eliminate complicated repair systems.

Areas that were accessible for rework have been evaluated by engineering on NCR's C-X-1897 and C-X-1925 and the necessary rework has been essentially completed. A reviewof the docu-mentation of concrete records revealed that there are also a limited number of concrete imperfections that were repaired and are no longer accessible. The inaccessible imperfections will be evaluated and dispositioned on NCR C-R-2040.

III. 'Pr'o ected Com letion of Corrective Action and Submittal Date of the Final'Re'ort The evaluation of all repairs is forecast to be completed by December 1, 1980.

The final report will be submitted by December 15, 1980.

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PC EVA),UATION A'll) DISPOS l'I'JOY, OP CnNCRE r: REPAIRS P()R DER 79-12 rr.r,vosz:

1. To review the specification requirements and field procedures for clarity and supplement as needed to provide any additional criteria for control of the work.,

2. To identifv pneumatically placed repairs that do not meet specifica--

tion requirements in all units and as reported in DER 79-12 and initiate corrective measures.

IP'ESTIGATION PROCEDURES:

1. The evaluation and disposition of concrete repairs for DER 79-12 is shown by the flow diagram on page 3. All previously made repairs

.'ill be located physically and documented by mapping and sketching.

The documentation will be by unit, building, and area.

2. All suspected areas will be identified as acceptable or nonacceptable by tapping or visual examination/engineering judgement. The quality of existin" repairs vill be investigated using one of the techniques listed belcw. Those items that are determined to be defective will be dispositioned by category defined in Item 3. Those repairs classified as sound will be reviewed by the Resident Engineer and a

'ample selected for confirmation of soundness of repair.

Techni oues:

a. Tapping

b. Visual Exar,ination/Engineering Judgement

c. Drill'ing

d. Coredrilling

3. Determine the acceptance of the need for rework of the existing concrete repairs (see acceptance criteria). If rework is required, assign the repairs to categories as follows:

a. Cosmetic (surficial only to 1 inch depth)

b. Hinor (up to first layer of rebar). NOTE: If the first layer of rebar is significantly exposed, the repair will be catego-rized as major.

c. Najor (first layer of rebar and beyond).

4 ~ Areas of existing repair (minor or major) near major equipment foundations will be reviewed on a case by case basis by Engineering.

Areas of existing repairs noted in inaccessible areas will be reviewed on a case by case basis by Engineering.

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<;>>>.'i I i<<n <~j Concrete Repairs for DER 7<3-12 Pn).e 2 CRITERIA-ACCEPTANCE/RrW'ORE OR REPAIR:

1. The investigation techniques and procedures are defined as follows:

a. Tapping - This method is used to determine the density and

-bond of the repair. If"C>>.

the repair sounds solid, it will be given a classification If an immediate indentation is noted upon tapping, it will be given a classification "B".

b. Physical Examination/Engineering Judgement - Used in conjunction with tapping to assure good bond and high density of repair material. Also, location of repair and size of repair is considered in classification noted in (a) above.

C ~ Drilling Use change in speed of drill to determine soundness of concrete. Speed of drill should change dramatically when drilling through defective repair and striking sound concrete.

d. Coredrilling - Samples vill be tested to assure desired strength has been reached.

2. If any of the random selection of 30 percent of classification>>C" repairs fail, then an additional 20 percent of the repairs must be reviewed. If no more failures are found, the procedure may stop.

If additional failures are found, then all classification "C" repairs must be reviewed.

3. Rework or repair will be accomplished using the latest specification requirements in field procedures.

DOCtÃiENTATION:

l. The existing repaired areas categorized as cosmetic, that are satisfactory will be noted on the mapping sketches and will become part of the final DER Evaluation Report. Cosmetic areas found needing rework shall be documented for rework by a Rework Tag (Ref.

~VP/Ocl No. 5.0).

2. The existing renaired areas categorized as minor, that are found to need rework, shall be documented for rework by a Rework Tag. (Ref.

4'PP/QCI No. 5.0).

3. 'Ihe ex'sting repair areas categorized as major, that are found to need rework, shall be documented on an NCR and repaired in accordance with Engineering disposition. (Ref. >TPP/OCI No. 5.0).

4. A report of the investigation by Unit, shall be prepared by Civil Field Engineering. The category, action date initiated, date rework/repair completed, and any other information considered applicable vill be recorded and vill form the basis for the Final DER Evaluation Report.

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