ML19209A067

Discusses Corrective Actions Re Missing Reinforcement Steel in Standby Svc Water Cooling Tower Basin.Reanalysis Shows Cooling Tower Basin Will Retain Structural Integrity Under All Loadings

ML19209A067
Person / Time
Site:	Grand Gulf
Issue date:	04/15/1977
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209A061	List: IR 05000416/1977004 ML19209A060 ML19209A067 ML19209A068
References
AECM-77-20, NUDOCS 7910010838
Download: ML19209A067 (2)

Text

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MISSISSIPPI POWER & LIGH f CO' PANY

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liciping Build Mississippi 2 2 P. O. BOX 1G40. JACKSON. MISSISSIP PI 3 9205 T.

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April 15, 1977

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's office of Inspection and Enforcement "U. S. Nuclear Regulatory Commission

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Region II - Suite 818 230 Peachtree Street, N. W.

Atlanta, Georgia 30303

?,? D 'ii):1?p Mr. Norman C. Moseley,' Director

! Q.,o(jp Attn:

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Dear Mr. Moseley:

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SUBJECT:

Grand Gulf Nuclear Station Units 1 6 2 Docket Nos. 50-416/417 File 0272/0498/15525/15526 Final Report-Withdrawal of a Significant Deficiency (Missing Reinforcement Steel -

in Standby Service Water Cool-ing Tower Basin) Number 76/8 AECM-77/20 on October 19, 1976, Mississippi Power and Light Company reported a possible significant deficiency to the U. S. Nuclear Regulatory Conmission, Region II, concerning missing reinforcement steel in the Standby Service Water Cooling Tower Basins.

On November 19,1976, FT6L filed an Interim Report, Letter AECM-76/55, on this problem which was then considered to be a significant deficiency.

Since that date we have determined this is areportablesignificantdeficiencyasdefinedby10CFR50.55(e)[

not The following is a description of the reported deficiency:

Design documents had specified horizontal dowels (reinforcing bars) installed at six (6) inch center-to-center vertical spacing the junction of the interior and exterior walls of the Standby at Service Water Cooling Tower Basins..These horizontal dowels are incorrectly installed on twelve (12) inch center-to-center vertical spacings.

The primary design requirement for this steel is to resist the hydrodynamic surges of the impounded water during the safe shutdown earthquake.

Extensive Engineering reanalyses were conducted, considering the as-built horizontal dowel spacings and all recorded nonconforcances, with the conclusion that the structural integrity and function of the basins are not adversely affected.

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.3 5.utwANY Mr. Norman C. Moseley U. S. Nuclear Regulatory Cacmission April 15, 1977 AECM-77/20 Branch,. December 8,1976, at Bethesda, Maryland, to pres the analytical approach which considers the original design in terms of the missing rebar.

The reanalysis considers the as-built envelopes the maximum horizontal bending condition that occurs in the condition which divide wall between the top of the base mat and bottom of the roof slab the intersection of the exterior walls.

at It the reported deficiency does not was therefore concluded that require a repair design.

As a result, it is concluded that the Standby Service Water Cooling Tower Basins as constructed retain their structural integrity and function under all loadings.

Corrective actions relative to the Quality Assurance program which have been identified have been reviewed and confirmed for adequacy to prevent recurrence.

Documentation of the detailed analyses and corrective actions taken will be available for review by Region II Inspectors at I

construction site.

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Yours trul e/

1. 7/ J. P. McGaughy, Jr.

Proj ec t Manager TER:dv cc:

Mr. R. C. Travis Mr. T. B. Conner Mr. N. L. Stampley Dr. Ernst Volgenau, Director Division of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.

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QSC Members Mr. T. W. Habermas Mr. D. M. Lake Mr. W. C. Hesslbein Mr. P. J. Bender Mr. T. E. Reaves Mr. W. L. Nail Mr. P. W. Sly Significant Deficiency Mr. C. W. Sandford Mr. J. E. Wimberley l

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