ML20028E864

Testimony of P Shunmugavel Re Structural Evaluation of Auxiliary Bldg for Seismic Shakedown Settlement & Seismic Category I Duct Banks.Auxiliary Bldg Able to Withstand Effects of Shakedown Settlement

ML20028E864
Person / Time
Site:	Midland
Issue date:	01/24/1983
From:	Shunmugavel P BECHTEL GROUP, INC., CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML20028E859	List: ML20028E858 ML20028E864
References
ISSUANCES-OL, ISSUANCES-OM, NUDOCS 8301280244
Download: ML20028E864 (34)

Text

r SS: STATE OF MICHIGAN COUNTY OF WASHTENAW 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 ) 50-329 OL 50-330 OL sMidland Plant, Units 1 & 2))

AFFIDAVIT OF PALANICHAMY SHUNMUGAVEL My name is Palanichamy Shunmugavel. I am an Engineering Specialist in the civil / structural department of Bechtel Power Corporation in Ann Arbor. In this capacity I am responsible for providing consultation to civil /etructural engineers working for Bechtel and for reviewing their work. I have a B.E. in Civil Engineering, M. Tech. in Structural Engineering, and a Ph.D. in Civil Engineering. I am a registered professional engineer in the state of California.

In connection with my role as Engineering Specialist, I have been assigned the responsibility for the

. Testimony concerning structural evaluation of the auxiliary building for seismic shakedown settlement. I have reviewed in detail the related structural evaluations.

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l I swear that the statements contained in this affidavit, and the Testimony are true and correct to the best of my knowledge and belief.

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_0 i PALANICHAMY SHUNMUGAVEL SIGNED AND SWOaN TO BEFORE me this cM/ day of 91xua ,, 1983.

. %w hsew NOTARY PUBLIC VERA G. ALLUM Notar9 Public, Washtenaw County, Michigan My Commission Expires November 13,1984 1

i 1552a

e UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of ) Docket Nos. 50-329 OM 50-330 OM CONSUMERS POWER COMPANY ) 50-329 OL 50-330 OL (Midland Plant, Units 1 & 2))

TESTIMONY OF DR. PALANICHAMY SHUNMUGAVEL ON BEHALF OF THE APPLICANT REGARDING STRUCTURAL EVALUATION OF AUXILIARY BUILDING FOR SEISMIC SHAKEDOWN SETTLEMENT AT THE MIDLAND SITE

STRUCTURAL EVALUATION OF AUXILIARY BUILDING FOR SEISMIC SHAKEDOWN SETTLEMENT

1.0 BACKGROUND

1.1 SCOPE OF TESTIMONY

.1 This testimony presents an adequate and reasonable basis for assurance that upon completion of the remedial action, the auxiliary building will be fully capable of withstanding the effects of shakedown settlement under the railroad bay and the liquid radwaste area.

1.2 FUNCTION AND DESCRIPTION The auxiliary. building is a large (approximately 230 feet along the north-south direction, 150 feet along the east-west direction, and 140 feet high) mainly reinforced concrete structure located north of the turbine building and between the two containment buildings (Figure 1). The liquid radwaste area and the adjacent railroad bay are appendages to the auxiliary building and are l

located at the northern end of the auxiliary l

building. The liquid radwaste area is

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approximately 50 feet long in the east-west direction, 28 feet wide in the north-south direction, and 45'-0" high. It has a roof slab l'-0" thick at elevation 659' and foundation slabs The 4'-0" thick at elevations 634.5' and 614.0'.

railroad bay is approximately 80 feet long in the east-west direction, 28 feet wide in the north-south direction, and 25 feet high. It has a roof slab of l'-0" thick at elevation 659 and a foundation slab of 4'-0" thick at elevation 634.5'. The foundation slabs rest on cohesionless granular backfill material. There are reinforced concrete walls on all four sides with a common wall on line A between the main auxiliary building and the railroad bay / liquid radwaste area j (Figure 2). The liquid radwaste area contains tanks and other equipment used for processing radwaste materials. The railroad bay provide access for loading and unloading equipment and fuel assemblies.

1.3 SHAKEDOWN SETTLEMENT

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! It is anticipated that the granular soil will be affected by seismic shaking. The shaking will result in a densification of the granular soil that will cause approximately 0.12 inch of 3

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settlement under the railroad bay and the liquid l radwaste area following a safe shutdown FSAR earthquake of 0.12 g. For a larger earthquake of' O.19 g, the shaking will produce approximately I 0.25 inch of settlement (Reference 3).

2.0 ACCEPTANCE CRITERIA The auxiliary building is designated as a Seismic i Category I structure. As such, the underpinne'd structure is evaluated in accordance with the design criteria and applicable loads and load combinations described in FSAR Subsection 3.8.6.3, Revision 44 and in the previously submitted testimony of Burke, Corley, Gould, Johnson, and Sozen for the Midland Flant auxiliary building (Reference 1).

3.0 STRUCTURAL ANALYSIS i

The seismic shakedown settlement under the railroad bay.

and liquid radwaste area can mainly cause local effects with a potential for affecting the stress distribution in these areas and in the portions of the auxiliary building near them because the railroad bay and the I liquid radwaste area are small appendages to the auxiliary building. The shakedown settlement occurs because of seismic cyclic shear strain in the granular J

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material. The seismic shakedown settlement at the railroad bay and the liquid radwaste area will have minimal effect on the overall seismic behavior of the auxiliary building because the building will have translational and rocking excitations about its main foundation at elevation 562.0'. The analysis of the auxiliary building has revealed that the railroad bay and the liquid radwaste areas will not separate from the soil during an earthquake. Therefore, the seismic shakedown settlement effects will be pronounced for the loading condition following a large earthquake. The underpinned auxiliary building is analyzed for the following load combination using a detailed finite-element model described in Reference 1.

U = 1.4 (D + S HI

• 1* Ib + 8 H +

L where U = Required strength to resist design loads D = dead load L = live load 1552a 5

Pg = jacking preload effect S

, H = shakedown settlement effects This corresponds to the first load combination specified both in ACI 318 and ACI 349 codes modified to include the effects of seismic shakedown settlement and jacking preload. The shakedown settlement effect is included in the analysis by softening the soil springs under the railroad bay and the liquid radwaste area.

4.0 STRUCTURAL EVALUATION From the results of the above analysis, it is confirmed that the seismic shakedown settlement at the railroad bay and liquid radwaste areas has mainly local effect near column line A. Therefore, the portions of the auxiliary building between column lines AA and C and between elevations 614'-0" and 659'-0" are evaluated in detail for seismic shakedown effects.

In addition to the finite-element analysis using the BSAP computer program, hand analyses of various slabs and walls are made to determine out-of-plane shears and bending moments wherever applicable. The effects of e, out-of-plane shears and moments are combined with the effects of in-plane shears and normal forces.

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In the evaluation of a typical slab or wall, the amount of reinforcing steel required for in-plane and out-of-plane forces is determined and compared to the existing reinforcement. For all walls and slabs, the amount of existing reinforcement is greater than the reinforcement required to satisfy the acceptance criteria.

)

5.0 CONCLUSION

It is concluded that the auxiliary building, including ,

the railroad bay and liquid radwaste area, is safe for the effects of shakedown settlement.

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REFERENCES

1. Testimony of Edmund M. Burke, W. Gene Corley, James P. Gould, Theodore E. Johnson, and Mete Sozen on Behalf of the Applicant Regarding Remedial Measures for the Midland Plant Auxiliary Building and Isolation valve Pits

2. Consumers Power Company, Midland Plant Units 1 and 2, Final Safety Analysis Report, Docket 50-329, 50-350

3. Testimony of Richard D. Woods on Behalf of the Applicant Regarding Seismic Shakedown Settlement at the Midland Site 1552a 8

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SS: STATE OF MICHIGAN COUNTY OF WASHTENAW .

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 ) 50-329 OL 50-330 OL (Midland Plant, Units 1 & 2))

AFFIDAVIT OF PALANICHAMY SHUNMUGAVEL My name is Palanichamy Shunmugavel. I am an Engineering Specialist in the civil / structural department of Bechtel Power Corporation in Ann Arbor. In this capacity I am responsible for providing consultation to civil /

structural engineers working for Bechtel and for reviewing their work. I have a B.E. in Civil Engineering, M. Tech. in Structural Engineering, and a Ph.D. in Civil Engineering. I am a registered professional engineer in the state of California.

In connection with my role as Engineering Specialist, I have been assigned the responsibility for the Testimony concerning Seismic Category I duct banks. I have reviewed in detail the related evaluations.

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I swear that the statements contained in this  !

affidavit and the Testimony are true and correct to the best of my knowledge and belief.

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PALANICHAMY SHUNMUGAVEL SIGNED AND SWORN TO BEFORE g e this c2(/dday of Gb , 1983.

O TOTARY PUBLIC

/d/S BECIADETTE A.%1LKE g Netary Public, Washtenaw C -

My Commission Expires Apr

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD i

In the Matter of ) Docket Nos. 50-329 OM 50-330 OM CONSUMERS POWER COMPANY ) 50-329 OL 50-330 OL (Midland Plant, Units 1 & 2))

TESTIMONY OF DR. PALANICHAMY SHUNMUGAVEL ON BEHALF OF THE APPLICANT REGARDING SEISMIC CATEGORY I DUCT BANKS AT THE MIDLAND SITE P

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SEISMIC CATEGORY I DUCT BANKS

1.0 BACKGROUND

1.1 Scope of Testimony This testimony presents an adequate and reasonable basis for assurance that the seismic Category I duct banks in Midland plant are fully capable of performing their intended safety function under all postulated conditions. This testimony also .

addresses references to " conduit" in Warren's contention 3 and Stamiris's contention 4.

1.2 Function and Description The function of the duct banks is to ensure, under all postulated conditions, the integrity of buried safety-related electrical cables by providing a casing around the cables.

l The duct banks are rectangular in c.coss-section.

Their dimensions generally vary from 18" x 19" to 74" x 20". They are buried at various depths from 3' to 40' below the grade level at the site. They l

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are constructed of concrete with a minimum compressive strength of 3,000 psi. A red dye is added to the concrete to identify the duct banks during future excavations. A nominal amount cf grade 60 reinforcement is provided in the duct -

banks. Two to four inches in diameter plastic or steel conduits are placed inside a duct bank with a minimum concrete cover of 6 inches. Electrical cables are pulled through and placed inside the conduits. The layout of Seismic Category I duct banks at the Midland site and a typical cross-sectional detail are shown in Figure 1.

1.3 Postulated Conditions The following postulated conditions are considered to ensure that the duct banks can perform their safety function:

a) Normal b) Construction c) Settlement d) Earthquake 1602a 2

2.0 ACCEPTANCE CRITERIA Based on the function of duct banks, the following conservative acceptance criteria have been developed:

a) Allowable concentrated shear deformations in the conduits based on the maximum amount of cable-fill (cable-fill is the percentage of the total cross-sectional area of the conduit that is taken up by the cables) are the following:

Conduit Maximum Existing Concentrated Diameter  % of Cable-Fill Shear Deformation 2" 20% 1.4" 3" 56% 1.1" 4" 51% 1.6" Concentrated shear deformar in can occur, for example, in a conduit at the interface between a building and a duct bank due to differential settlement.

l b) Longitudinal strain corresponding to the allowable l

cable-pulling tension is 0.333 x 10-8, which is l

, several times smaller than the strain corresponding to the breakage of cables.

c) The minimum bend radius varies from 1.7" to 17" depending on the cable type.

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3.0 EVALUATION 3.1 Normal Condition During the normal operating conditions, the duct banks are buried in the earth. The soil overburden, surcharge and live loads from surface traffic have been determined to have minimal effects on the cables. The cables in the duct banks are suitable for direct burial in wet and dry earth and they have a service life expectancy of 40 years. -

3.2 Construction Conditions The conduits and the duct bank concrete protect the space for cables from being obstructed with laitance and other trash. Before pulling cables through a duct, the duct is cleaned and checked for continuity and obstructions by pulling a segmented hard fiber composition mandrel (rabbit) as shown in Figure 7-3 in Appendix A through it.

The concrete duct banks are protected from the nearby construction activities by placing sufficient earth cover over them.

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The temporary and permanent site dewatering systems can produce some settlement of the duct banks. The maximum estimated dewatering settlement is l'itich. This is included in the evaluation of duct banks for settlement as explained in Section 3.3 A freeze wall has been installed in conjunction with construction dewatering for the auxiliary building.

Seismic Category I duct banks cross the freeze wall at two locations. At each location monitoring pits were installed and the soil around and below the ducts was removed to isolate the ducts from freezing effects.

Upon NRC staff approval, the portions of the ducts in the excavated pits will be encircled with 6"-thick polyethylene planks and backfilled with_ fly ash cement mixture and compacted soil.

3.3 Settlement Settlement of the duct banks has been estimated by the Bechtel Geotechnical Department taking into account the duct bank elevations and the dates of cable pulling in the duct banks. It has been estimated that the maximum settlement from October 1978 through the year 2025 will be 3 inches. It is noted that all of the cables in the 1602a 5

Seismic Category I duct banks were pulled in 1981 or after, except in one case where the cables were pulled in October 1978. As in the case of the prediction of 3 inches for underground piping, the maximum settlement prediction of 3 inches for duct banks takes into account secondary consolidation to the year 2025, dewatering effects, a 0.5-inch allowance for possible loading from laydown, and 0.25 inch for possible seismic shakedown settlement due to an acceleration of 0.199 The secondary consolidation and dewatering settlements are based on observations made on Borros anchors installed at various elevations in the plant fill. It was also estimated, based on profiles of existing underground piping made in 1981, that the 3-inch settlement of the duct banks could occur over a minimum distance of 25 feet.

Gradual settlement of duct banks in the general soil medium can have minimal effect on the cables. The cables are placed loosely in the duct banks and they generally have some slackness which can accommodate the settlement without stretching the cables. The cables themselves are made of ductile materials capable of considerable stretching before breaking. A conservative evaluation has revealed that the duct banks can tolerate 3 inches differential settlement 1602a 6

over a 12' length, corresponding to the allowable pulling strain of 0.333 x 10-8 This evaluation does not include the beneficial effects of slackness and ductility of the cables. Thus, the maximum estimated duct bank settlement of 3 inches over 25 feet of the site can be easily accommodated.

Differential settlement at various interfaces between buildings and duct banks has been determined to vary from 0.25 inch to 0.5 inch. The cables can accommodate up to 1.1 inch of concentrated shear deformation due to differential interface settlement as explained in the acceptance criteria.

Only the evaluation for the differential interface settlement effects to the north of the service water pump structure (SWPS) remains to be completed. It should be noted that the fill material north of the SWPS will be excavated for undttpinning SWPS and for rebedding the buried piping and duct banks with a fly ash cement mixture. If the evaluation shows that the i

i cables can not accommodate the concentrated shear deformation from the differential interface settlement at the north wall of the SWPS or at the interface between the fill and the fly ash cement mixture, the duct banks can be isolated either partially or completely from the concentrated shear deformation.

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l Figure 1 shows a possible detail where the duct bank is wrapped with ethafoam at its interface with a building.

c The evaluation of duct banks under the diesel generator building before and during the preload program is explained in the response to NRC 10 CFR 50.54(f) question number 7 (a copy of the response is attached as Appendix A). After the preload program, all the conduits in the duct banks were checked in May 1980 and no obstruction or discontinuity was encountered. The cables were pulled through and placed in those conduits in 1981.

3.4 Earthquake Effects of earthquake excitations on duct banks have been evaluated according to BC-TOP-4A for straight portions of buried duct banks and for bends and interfaces near the buildings. Seismic compression, shear, and surface wave effects have been included.

The seismic evaluation has determined the following maximum values from a 1.5 times FSAR safe shutdown earthquake:

a) Maximum strain in the straight portion is 0.00019.

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b) Maximum concentrated shear deformation at a bend is 0.23 inch c) Maximum concentrated shear deformation at an interface near a building is 0.32 inch.

These maximum values are well within those given in the acceptance criteria.

Interaction between a building and a duct bank is possible if the clearance between them along the axial direction of the duct bank is not sufficient to accommodate the maximum seismic relative motion between them. The effects of this seismic interaction are expected to be small because the maximum relative motion along the axial direction of the duct bank is 0.125 inch. The significance of such seismic interaction effects, if any, is being evaluated. If necessary, the seismic interaction can be eliminated by increasing the clearance between a building and a duct bank.

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r 4.0 Conclusion It is concluded that the Sef;mic Category I duct banks, upon the completion of remaini.sg evaluations and modifications if necessary, will be capable of ensuring under all postulated conditions the integrity of buried, safety-related electrical cables.

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T APPENDIX A RESPONSES TO THE NRC 10 CFR 50.54(f) REQUEST REGARDING PLANT FILL FOR MIDLAND PLANT UNITS 1 AND 2 CONSUMERS POWER COMPANY DOCKET NUMBERS 50-329 AND 50-330 l

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1 Question 7  ;

I Describe in detail how you will determine the adequsuy of l the electrical duct banks in view of the previous loading '

l caused by contact of the diesel generator building foundation with these banks. Describe corrective measures which may be taken in the event of unacceptable results.

Response .

Four electrical duct banks run south from the auxiliary building under the turbine building foundation and then turn upward and pass through the footings of the diesel generator building as shown in Figures 7-1 and 7-2. Exploration revealed that the duct banks were in direct contact with the footings and were restraining the diesel generator building settlement.

Parts of the diesel generator building footings and/or parts -

of the duct bank steps were removed to provide a 12-inch clearance for a vertical joint between the ducts and building footings. This was done to prevent direct load transfer from the building to the duct banks.

A summary of survey data taken during the duct bank isola-tion period is presented below:

Bay 1 Bay 2 Bay 3 Bay 4 (inches) (inches) (inches) (inches)

Building settlement before 1.56 .95 .97 1.09 isolation of ducts, November 10, 1978 Building settlement after 1.85 1.72 2.34 2.72 isolation of ducts, November 24, 1978 Rebound (upward movement) -

.06 .12 .18 of ducts, November 24, 1978 l (measured at top of duct I

bank) l Note: Bay locations are shown in Figure 7-1.

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During the week immediately after the duct banks were isolated, the east end of the diesel generator building (Bay 4) experienced )

the largest settlement and the auct bank in Bay 4 had the l largest rebound. It is therefore assumed that the duct bank in Bay 4 was supporting the largest imposed building load of the four duct banks. Based on visual observations of the gaps between the building footings and the mud mat, an estimated two-thirds of the east wall of the diesel generator building, or approximately 1,000 kips, was supported by the duct bank in Bay 4.

The duct bank deflection was assumed to be equal to the diesel generator building settlement before isolation.

Based on this assumption, the 1.56-inch deflection of Bay 1 and the 1.09-inch deflection of Bay 4 could result in strains in the duct bank reinforcing steel at Point A (see Figure 7-2) which exceed the yield strain. This estimate of strain is based on conservative assumptions and is therefore considered to be an upper limit value. .

The load transferred from the building to the duct bank was a one-time load which caused the duct bank to settle directly under the vertical section of the duct as shown by the small amount of rebound measured after the building load was released. Thus, the bending which could have caused the reinforcing steel at Point A to exceed the yield strain ~is due to settlement. Settlement primarily induces additional strain, which is a self-limited effect and will not affect the ultimate strength of the duct bank.

The function of the duct banks is to provide a space in the ground through which cables may be pulled. They also provide a casing around the cables to protect them during future construction activities in the area. The duct banks are not required to provide a watertight boundary around the cables.

Therefore, cracking of the duct banks due to differential settlement does not affect their design functions.

The assumed 1,000-kip load previously mentioned is the highest that will occur during the life of the plant. The i load due to settlement of the duct banks during the diesel generator building preload program will be larger than the load during the life of the plant, but less than the assumed 1,000-kip load.

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The strains induced in the dhet banks due to seismic effects are small (less than 10% of the yield strain) and, when added to the possible strains from settlement, will have no further effect on the function of the duct banks. There-fore, if the duct banks are still intact and continuous with no obstructions after the diesel generator building load has been removed and if the duct banks remain intact after the preload program has been completed, they will be able to withstand all future operating loads.

All four duct banks were checked for continuity and obstruc-tions after they were isolated from the diesel generator building footings. This was accomplished by pulling a segmented, hard fiber composition rabbit through each conduit (see Figure 7-3). The rabbit was pulled through the conduit by hand. No obstruction was detected during the pulling of the rabbit. The continuity check will be performed agair. after the preload program is completed. The results of this check, along with the results of the duct bank settlement survey, will be available after November 1979. l3 In the event that any significant obstructions or discontin-uities are encountered, several alternatives will be consid-ered to correct this condition. If the obstructions are small, a router may be pulled through the conduit to remove

, the obstruction and provide a smooth transition through the conduit. Replacement and rerouting of the duct bank will be studied as alternatives in the event of large discontinuities of the duct bank.

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j FIGURE DATE: 4/24/79 g

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e r 1 1

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INSIDE DIAMETER OF CONDUIT = 4'4 OUTSIDE DIAMETER OF MANDREL = 3 43'

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DIAGRAM OF MANDREL .(RABBlT)USED TO CHECK CONDUITS 1

MIDLAND PLANT UNITS 1 & 2 CONSUMERS POWER COMPANY

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RAH 11TT FOR ELECTRICAL DUCT-FIGURE 7-3 DATE: 4f24/79

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