ML20004F417

Interim Deficiency Rept Re Cracks in Borated Water Storage Tank Foundation.Design Forces & Stresses Will Be Submitted in Future Repts When Current Detailed Analysis Is Complete. Next Rept by 810814

ML20004F417
Person / Time
Site:	Midland
Issue date:	06/12/1981
From:	Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, 12015, MCAR-48, NUDOCS 8106180318
Download: ML20004F417 (6)

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and Constrnctson 81-03 #3 General OMices: 1945 West Parnell Fload, Jackson, MI 49201 * (517) 788-0453 June 12, 1981 c<'

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~1 l'r J G Keppler, Regional Director yfy

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CRACKS IN 3CRA*ED '4ATER STCRAGE TA'P" FCUNDA"'ICU FILE:

0.L.9.L9 UFI:

73*1C*01, C1100(E), 02362(S) SERIAL:

12015

References:

J W Cock letters to J G Keppler; Same

Subject:

(1) Serial 11201; dated February 20, 1981 (2) Serial 11528; dated April 3,1981 This letter, as were the referenced letters, is an interim 50 55(e) report concerning the existence cf cracks in the borated water storage tank foundat icn.

Enclosure i describes the status of planned remedial actions, which vere discussed with the :iRC Staff during the weeks of April 20, 1981 and May L, 1981.

Ancther report, either interic cr final, vill be sent en or before August ik, 1981.

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Inclosure 1: I'anagement Corrective Acticn Report MCAR L8, Interim Report 3, dated May 29, 1981 CC:

Director, Office of Inspection & Enfor:ement Att Mr Victor Stello, USNRC (15)

Director, Office of Management Information & Program Centrol, USURC (1)

RJCock, USI!EC Resident Inspector Midland Nuclear Plant (l',

810618031T 3-

2 Serial 12015 81-03 #3 CC: C3echhoefer, ASL3 Fanel RSDecker, ASL3 Panel FFCovan, ASL3 Panel AS&L Appeal Panel LS' Cherry, Esq MSinclair CRStephens, US:iRC

'4DFaten, Esq, US:;RC FJKelly, Esq, Attorney General SEFree=an, Esq, AFst Attorney General GTIaylor, Esq, Asst Attorney General

'AEM.arshall GJMerritt, C'iK&J P

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Scrial 12015 Bechtel Associates Professional Corporation e1-03 c3 031512

SUBJECT:

MCAR 48 (issued 1/29/81)

The Existence of Cracks in the Borated Water Storage Tank Foundation Units 1 and 2 i

i INTEREd REPORT 3 DATE:

May 29, 1981

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PROJECT:

Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220 Introduction Management Corrective Action Report (MCAR) 48 was issued on January 29, 1981, followed by two interim reports. This report provides a summary of the progress on the corrective action for the borated water tank foundations.

Background

The overstressed condition of the borated water tank foundations was revealed by a structural analysis which indicated the allowable moment capacity was exceeded in several locations in the foundation structures.

A visual inspection at these locations showed cracks in the Units 1 and 2 foundations. The cause of the overstressed condition-is attributed to the differential bearing pressure between the tank ring wall foundation and the valve pit.

The design of the foundations did not account for the i

additional bending induced by differential bearing pressure in the ring walls.

Corrective Action A three phase corrective action procedure has been developed. These measures and their current status follow.

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Surcharging a Portion of the Valve Pit and its Surrounding Area a.

(see Figure 1): The technical specification to perform the sur-charging and monitoring of the foundations has been prepared and is currently under review.

The surcharge operation will consolidate the fill beneath the valve pits, thereby reducing the amount of expected residual settlement over the 40-year life of the plant.

In addition, surcharging will reduce the dictortion of the ring walls, partially close the exist-l ing cracks, and reduce the tank shell deformation.

Bghtel Associates Professional Corporation 03I512 MCAR 48 Interim Report 3 "ay 29, 1981 Page 2 b.

Integrally Constructing a Reinforcing Ring' Beam Around the Existing Ring Wall (see Figures 1 and 2): The ring beam is sized to resist all the imposed loading from the tank, including the additional bending induced by the residual differential settlement between the ring wall and the valve pit.

The analysis and final design I

are underway. The shear from the existing ring wall will be trans-ferred to the new ring beam by dowels embedded in the existing ring wall. The cracks in the vicinity of the dowels in the' existing ring wall will be repaired to ensure proper shear transfer. The resul-tant torsion in the new beam due to eccentricity of the load will be considered in the analysis of new beam and rebar requirements.

The fill and drain lines will be cut prior to surcharging.

The 18-inch process lines have already been cut.

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Resetting the Tank on the Existing Ring Wall to the Original Con-struction Tolerance if Required: The tank vendor has been rm-quested to develop a procedure for resetting the tanks.

Future Action Items The corrective actions for the borated water storage tank founcations were presented to the NRC as part of the Midland project structural design audit during the week of April 20, 1981, and meetings with the NRC staff during the week of May 4, 1981. The open items generated in this meeting regarding beam design and its effect on pipes penetrating the valve pits have been addressed in the previous section.

The design forces and stresses will be submitted in future reports when the current detailed analysis is complete.

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Fipre I REMEDIAL MEASURES FOR BWST FOUNDATION STRUCTURE

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