ML17296A933

Ack Receipt of Re Deficiency Rept Re Discrepancy in Reinforcing Steel Segments of Circumferential Joint Between Containment Shell & Basemat

ML17296A933
Person / Time
Site:	Palo Verde
Issue date:	08/12/1980
From:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
References
NUDOCS 8008270504
Download: ML17296A933 (12)

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NUCLEAR REGULATORY COMMISSION REGION V 7990 N. CALIFORNIABOULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94596 AUG 12 1980

.Docket No. 50-528, 50-529, 50-530 Arizona Public Service Company P. 0.

Box 21666

Phoenix, Arizona 85036 Attention:

Mr. E.

E.

Van Brunt, Jr.

Vice President, Nuclear Projects and ANPP Project Director Gentlemen:

Subject:

A 50.55(e) Potentially Reportable Deficiency Relating to a Discrepancy in Reinforcing Steel Segments of Circumferential Joint Between Containment Shell and

Basemat, Palo Verde Nuclear Generating Station, Units Pl, 82, and 83 (Your Letter of July 28, 1980)

Thank you for your letter, referenced

above, which forwarded an interim report pursuant to 10 CFR 50.55(e) regarding the subject matter.

Your report will be reviewed and evaluated, and we are looking forward to receipt of your final report on this matter.

Your cooperation with us is appreciated.

Sincerely, IgI-O~.;<C R.

H. Engelken Director 8 0 08 8 Y05gf

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'HOENIX'RI2ONABSO36 July 28, 1980 ANPP-16016-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:

An Interim Report of a Potential 50.55(e)

Reportable Condition Relating to Reinforcing Steel Shown in Drawings that May Not Be Accurately Reflecting the Actual Design in Certain Areas (DER 80-19)

File:

80-019-026

Reference:

Telephone Conversation between J. Eckhardt and B.

S. Kaplan on July 1,

1980, same subject

Dear Sir:

Attached, is an interim report of the potential reportable deficiency under 10CFR50.55(e) referenced above.

The final report should be submitted by October 31, 1980.

EEVBJr/JAR:skc Attachment Very truly ours W.F. o~

E.

E. Van Brunt, Jr.

APS Vice President Nuclear Projects ANPP Project Director

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U. S. Nuclear Regulatory Commission Attention:

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Spencer, Chief ANPP-16016-JAR July 28, 1980 Page 2

cco Victor Stello, Jr., Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D.

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INTER'EPORT POTENTIALLY REPORTABLE DEFICIENCY 50.55(e)

ARIZONA PUBLIC SERVICE COMPANY (APS)

PVNGS UNITS 1, 2 AND 3 I

Descri tion of Deficienc During a review and comparison of the containment shell calculations and drawings, an apparent discrepancy in the reinforcing steel was discovered in certain local segments of the circumferential joint between the con-tainment shell and the basemat.

The segments in question are those which have mechanical penetrations located ten to fifteen feet above this joint.

These penetrations interrupt the main vertical shell reinforcement.

As a result of fuxther investigation, it was determined that the interrupted reinforcement was partially replaced by additional main reinforcement added between the pene-trations and anchored into the basemat (a closer rebar spacing was utilized between the penetrations).

The amount of reinforcement that was added depended on the distance between the penetrations.

In a few areas, the added rein-forcement does not equal the intexxupted reinforcement.

In many areas, the amount of added reinforcement exceeds the amount of interrupted reinforcement.

Therefoxe, the total amount of reinforcing steel between adjacent buttresses is adequate to withstand the total load, but the strategic location and distribution of these bars may be questionable.

Trim steel was also added between the penetrations, but this trim steel was not anchored into the basemat.

The impact of the steel pattern selected is that the rein-forcing steel in selected segments of the containment wall may slightly exceed the allowable stress limits established in the design criteria for certain load combinations based upon the conservative linear-elastic analysis used which does not take advantage of changes in stiffness due to concrete cracking.

This potential problem is not.one which compromises containment integrity in an overall sense, but is one which could result in slight stress redistribution as a result of stresses in excess of allowables in local areas.

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Interim Report Page 2

II Status of Resolution The design of the containment structure is based upon a conservative linear-elastic analysis which does not take advantage of changes in stiffness due to concrete cracking.

This approach results in conservative rebar selection as it is known that when material nonlinearities are con-sidered in an analysis, the resultant section forces will be smaller.

To complete the evaluation, a computer analysis utilizing the FINEL program is being completed.

The analysis will take into account the material nonlinearities which exist under some loading conditions and which will result in the more accurate redistribution of the load.

The FINEL stress analysis is discussed in the PSAR Section 3.8.1.4.3.B.

III Corrective Action Plan The results of the FINEL analysis, when compared to the original linear-elastic analysis, will indicate reduced stresses "n the reinforcing steel.

It is expected that the results of the FINEL analysis will demonstrate that there is adequate margin in the existing structure to resist the design criteria load combinations.

In addition to meeting the requirements of the ASi~fE Section III, Division 2,

Code, it is expected that this analysis will also result in main-taining the additional project design margins.

If the results of the FINEL analysis do not adequately resolve the potential overstress condition, several alter-natives will be investigated.

These include taking advantage of the actual material properties for the concrete and rebar instead of the design values and/or using a slight increase in the prestress level at transfer, permissible under the ASHE Section III, Division 2, Code.

As required in FSAR Section 3.8.1.5.1, the containment is designed for the factored loads and load combinations given in the ASIfE Section III, Division 2, Code supplemented by additional requirements included in BC-TOP-5-A.

These load factors and load combinations provide the factors of safety for the containment.

The approach of using the FINEL program and actual material properties of the concrete and rebar will provide a more realistic means of evaluating the strength of the containment and for verifying that the containment is in compliance with project design margins, the ASNE Code and SAR commitments.

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Interim Report Page 3

IU Com letion Commitment The evaluation and final report are forecast to be completed by October 31, 1980.

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