ML20040F451

Testimony of RP Kennedy & Rd Campbell.Uneven Tank Support Resulting from Soil Settlement Has Not Damaged Borated Water Storage Tanks.Design Basis Has Not Been Violated Nor Safe Operating Life Reduced

ML20040F451
Person / Time
Site:	Palo Verde, Midland
Issue date:	02/04/1982
From:	Campbell R, Kennedy R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.), STRUCTURAL MECHANICS ASSOCIATES
To:
Shared Package
ML20040F449	List: ML20040F448 ML20040F451 ML20040F458
References
ISSUANCES-OL, ISSUANCES-OM, NUDOCS 8202090213
Download: ML20040F451 (5)

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2]yl?2 UNITED STATES OF AMERICA NUCLEAR REGULATORY' COMMISSION ATOMIC SAFETY AND LICENSING BOARD In The Matter of ) Docket Nos. 50-329 OM 50-330 OM CONSUMERS POWER COMPANY l

) Docket Nos. 50-329 OL (Midland Plant, Units 1 and 2)) 50-330 OL ,

TESTIMONY OF ROBERT P. KENNEDY & ROBERT D. CAMPBELL This is a joint testimony of Dr. Robert P. Kennedy and Robert D. Campbell.

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Dr. Robert P. Kennedy is President of Structural Mechanics Associates, Inc. (SMA) located at 5160 Birch Street, Newport Beach, California. Robert D. Campbell is employed at SMA in the role of project manager and reports both technically and administratively to Dr. Robert P. Kennedy. SMA has been retained by Consumers Power Company since September 1980 'to act as general consultants to assist in reviewing specialized aspects of the design of the Midland Plant. The Midland Plant consulting work performed by SMA is under the direct supervision of Robert P. Kennedy. Mr. Robert Campbell is one of the senior personnel in SMA assigned to perform specific consulting tasks under the direction of Dr. Kennedy.

Dr. Robert P. Kennedy has over 19 years of consulting experience in the design and analysis of structures and components. Mr. Robert D. Campbell has over 20 years experience in design, analysis and fabrication of nuclear power plant components and component test facilities. A statement of the qualifications of Dr. Robert P. Kennedy has been previously submitted. A statement of the qualifications of Robert D. Campbell is attached to this testimony as Attachment A.

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9202090213 8202O4 PDR ADOCK 05000329 T PDR

., o This testimony concerns the evaluation of the Midland Plant Borated Water Storage Tanks (BWSTs) for stresses incurred under uneven support conditions resulting from soil settlement and consequent distortion of the ring walls that support the BWSTs. A study was conducted of the settlement induced stresses in the BWST's to verify that no damage had been incurred during the worst combination of uneven support conditions and uneven anchor bolt loading. Verification of the tanks' integrity and prediction of the tanks' response to uneven suppcrt conditions was desired prior to performing remedial work on the ring wall supports and re-leveling of the tanks.

There are two tanks of concern, designated Tank IT-60 and 2T-60.

Field measurements of ring walls top surface contours and anchor bolt loads we're performed by others. These field measurements defined the extent of uneven support and uneven anchor bolt loading acting on the two tanks.

Examination of the field measurement data by SMA indicated that tank IT-60 was exposed to the more severe conditions and that verification of the in-tegrity of Tank IT-60 would unquestionably verify the integrity of Tank 2T-60.

Tank IT-60 was evaluated by performing a finite element analysis of the most severe loading and ncn-uniform support conditions that existed at any time to date. The present condition is much less severe than the condition that existed in June 1981. Information provided to SMA for the evaluation included tank and ring wall drawings, field survey measurements of the eleva-tions and thus the contour of the tops of the ring walls, field measurements of anchor bolt loads (determined by strain gaging the bolts), a history of the tank filling and draining and a sample of the compressible asphalt impregnated fiberboard material that is placed between the tank bottom and the ring wall.

Under a subcontract to SMA, the asphalt impregnated fiberboard was' tested in l a laboratory to determine its force-deflection properties for use in the finite element modeling.

From the experimentally determined anchor bolt loading and the known weights of tank components, all loading conditions were known. The non-uniform support reactions and resulting tank wall stresses were computed utilizing the finite element model and incorporating laboratory determined properties of the compressible asphalt impregnated fiberboard upon which the tank rests.

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An engineering report that describes details of the finite element model, analysis procedures and res alts is attached to this testimony as Attachment 8.

The intent of the BWST evaluation for soil se'ttlement induced stresses

. was to demonstrate that no damage had resulted to the tanks. In order to esta-blish a' stress or load level that would unquestionably be acceptable and guaran '

tee that no damage to the tanks had occurred, applicable design code allowable working stress levels were utilized. .The governing dcsign code is the ASME Boiler and Pressure Vessel Code,Section III, Nuclear Power Plant Components, Subsection NC, 1974, supplemented by ASME Code Case 1607-1 to establish allowable stresses for conditions other than nonnal operation (infrequent events). Settlement induced stresses are not specifically covered by the design code rules, thus the intent of the code wasLapplied to this condition.

The stress acceptance criteria used in evaluation of the BWSTs are based on two levels of allowable stresses. The firs't level of allowable stresses are normal operating condition stress levels for which no further examination or special inspections would be required or recommended. The second level of stress or load would be that associated with plant emergency conditions (infrequent loading events). At this level the governing design code re-cognizes that some permanent deformation is possible but that the. equipment l will remain serviceable. In cases where the higher emergency event stress allowables are approached, SMA reconinended that additional non-destructive examination be conducted to verify that no cracking or excessive deformation had occurred.

This is not a specific code requirement but is considered prudent to assure that small amounts of yielding do not result in conditions that would reduce the tanks' design strength or alter the fabricated quality of the tanks.

The normal operating stress limits of the governing design code were met with two exceptions. One exceptions was that the most highly loaded bolt chair top plate did not meet normal operating stress limits, but-the emergency event loading criteria for an ASME Code class 1 plate and shell type component i support were met. A subsequent dye penetrant examination (performed by others) of the top plate welds verified that no cracking was present. Careful visual examination performed independently and at different times by Dr. Robert P.

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Kennedy and Robert D. Campbell did not indicate any visable deformation or damage to any bolt chairs.

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The other e'xception was local tank wall compressive stresses which did not meet normal operating stress limits. Again, the emergency event buckling criterion was used to verify freedom from buckling. A buckling factor of safety of 2.46 was also calculated to demonstrate that a large margin existed for tank buckling. A visual examination of the tanks performed by Mr. Campbell while they were under their most highly stressed conditions also verified that no buckling was present.

A summary of maximum resulting stresses and loads for the crit-ical areas examined is tabulated in Table 1. Note that the stresses and loads in Table 1 summarize the most severe conditions that existed prior to backing off the anchor bolt loads and surcharging the ring wall valve pits. Current stress and loading conditions are much less severe than those evaluated and summarized in this testimony.

It is therefore concluded that the uneven tank support which resulted from soil settlement has not~resulted in any damage to the BWSTs, that their design basis has not been violated nor has their safe operating life been reduced.

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TABLE 1 -

SUMMARY

0F STRESSES l

Maximum Normal Operating Yield Stress / Emergency Condition Area Type of Stress Stress or Stress Allowed Buckling Capacity Stress / Load Allowed Load by Design Code or Limit Load Sy Design Code Tank Wall Primary Membrane 12.50 ksi . 15.7 ksi 25.0 ksi 23.5 ksi Tank Wall Compression -1.93 ksi(I) -1.4 ksi -4.75 ksi -2.1 ksi Tank Wall at Bolt Chair Local Membrane' 19.59 ksi 23.5 ksi 25.0 ksi 28.2 ksi Anchor Bolt Tension 22.32 ksi(2) 29.0 ksi(3) 36.0 ksi 38.6 ksi Bolt Chair Primary Bending 31.31 kips (2) Limit Analysis Not 39.95 k1ps 32.0 kips (4)

Top Plate (Limit Analysis Applicable to Normal Used for Eval- Operating. Conditions uation)

1. Factor of Safety on Buckling = 2.46

2. Maximum measured stress or load

3. Allowable stress from 1980 ASME code for component support bolting.

Governing design code does not contain allowables for A-36 anchor bolts.

4. Limit analysis criterion for 1980 ASME Class 1 plate and shell type component supports was used.

Governing design code does not contain specific criterion for limit analysis of component supports.

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