ML20004C779

Third Interim Deficiency Rept Re Auxiliary Bldg Seismic Analysis.Structural Response Analysis Completed.Seismic Qualification Records Reviewed.Steel Superstructure Checked & Found Adequate.Next Rept by 810731

ML20004C779
Person / Time
Site:	Midland
Issue date:	05/29/1981
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, 12008, 81-02-#3, 81-2-#3, MCAR-47, NUDOCS 8106050224
Download: ML20004C779 (8)

Text

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g e Consumers I

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\ A l Power U

James W Cook Vice President - Projects, Engineering and Construction Generea offices: 1945 West Perne!! Road, Jackson. MI 49201 * (517) 78& O453 May 29, 1981 81-02 #3 N

& Cb Mr J G Keppler, Regional Director pp Office of Inspection and Enforcement 8 li .]

) IDS J US Nuclear Regulatory Commission I= '

L Region III 97 JUN 0 <f19OI 5 IO 799 Roosevelt Road -

Glen Ellyn, IL 60137 Mygroa /C E 4'//

MIDLAND PROJECT -

DOCKER NOS 50-329, 50-330 4 ~g ('

AUXILIARY BUILDING SEISMIC ANALYSIS FILE: 0.h.9.48 UFI: 73*10*01, 70*0l*11*03, 45*05*20 SERIAL: 12008 Ruference: CPCo letters to J G Keppler, Same

Subject:

1) Serial No 11200, dated February 20, 1981

2) Serial No 11972, dated April 16, 1981 This letter, as were the referenced letters, is an interim 50.55(e) report

, concerning the auxiliary building seismic analysis. Attachment 1 provides j a status of the planned corrective actions.

i Another report, C.ther interim or final, will be sent on or before July 31, 1981.

WRB/lr Attachment 1: MCAR-47, Interim Report No 3, dated May 15, 1981

" Auxiliary Building Seismic Analysis" CC: Director of Office of Inspection & Enforcement Att Mr Victor Stello, USNRC (15)

Director, Office of Management Information & Program Control, USNRC (1)

RJCook, USNRC Resident Inspector Midland Nuclear Plant (1) l 81060502 24

2 Serial 12008 81-02 13 CC: CBechhoefer, ASLB Panel RSDecker, ASLB Panel

. FPCowan, ASLB Panel-

'AS&L Appeal Panel IC4Cherryi Esq MSinclair CRStephens, USNRC

-WDPaton, Esq, USNRC FJKelly, Esq, Attorney General SHFreeman, Esq, Asst Attorney General GTTaylor, Esq, Asst Attorne'y General WHMarshall , .

GJMerritt, Esq, TNK&J ,

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Serial 12008 81-02 #3-CC: C3echhoefer, ASL3 Panel RSDecker, ASLB Panel

~FPCowan, ASLB Panel AS&L Appeal Panel 4, HMCherry, Esq , , ,

MSinclair CRStephens, USNRC '[ *

'nDPaton, Orq, US:GC FJKelly, Esq. Attorney General SHFreeman, Esq, Asst Attorney General GTTaylor, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, THK&J l

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Attacharnt 1 serial 12008

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Bechtel Associates Professional Corporation 81-02 #3

SUBJECT:

MCAR 47 (Issued 1/29/81)

Auxiliary Building Seismic Analysis INTERDi REPORT ~3 DATE: May 15, 1981 PROJECT: Consumers Power Company Midland Plant Units 1 and 2.

Bechtel Job 7220 Description During a seismic reanalysis associated with the 10 CFR 50.54(f) plant fill issue, it was noted that the 1977 auxiliary building seismic model considered the control tower and the main portion of the auxiliary building as an integral unit between el 614' and 659'. This assumption may not be appropriate for the north-south direction because of the connection between the control tower and the main atructure, which con-sists primarily of reinforced concrete slabs. The auxiliary building and the control tower were structurally desianed to a 1974 seismic model which included flexibility at the connection between the control tower and main structure. Equipment and systems have been seismically qual-ified using output from both the 1974 and 1977 seismic models.

Potential Safety Implications This item does not have a safety impact on the stability of the auxi-liary building, equipment, structural steel superstructure, or the structure of the main part of the auxiliary building. Potential safety implications have not yet been determined for the control tower, its connections to the main auxiliary building, the electrical penetration areas, or the piping systems.

I Investigation The investigation presented is limited to the new definition of the north-south,1977 seismic model (FSAR Figure 3.7-10) initiated solely to determine the safety impact of the condition. Because the control tower and the main auxiliary building (el 614' to 659') were modeled as two separate structures connected by a flexible link, this investigation considers possible changes in the building forces and floor response spectra curves. The structural behavior in the east-west and vertical directions would not be affected by this change in the model.

The investigation presented herein does not include the model modifi-cation in process to resolve analysis necessary for the 10 FCR 50.54(f) plant fill issue.

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l Bechtel Associates Professional Corporation 1 l

MCAR 47 Interim Report 3 - 030693 May 15,.1981 Page 2 The investigation with this modei considers:

1) A response spectrum analysis to develop building responses

- 2) A time-history analysis to develop instructure floor response spectra at selected locations

3) Comparison of building responses to values calculated in 1974 and 1977, and to allevable forces if necessary I

4) Comparison of instructure floor response spectra to those gene-rated in 1977, at selected locations, and comparison of loads in selected piping systems and equipment systems to allowable loads if necessary.

The current status of this investigation follows.

1) The response spectrum analysis has been completed.

2) The time-history analysis and selected instructure floor response spectra have been generated. -

3) A comparison of the building forces at the base has been made. The total building base moment and shear have increased by 2%'and 1%,

respectively, values that are not significant with respect to overall building stability. The greatest change in building forces was confined to the structural steel superstructure, the control tower, and the electrical penetration area at el 674'-6" and above. '

The moment and shear in the control tower, the electrical penetra-tion area, and the slabs connecting the control tower to the main auxiliary building are under investigation. By inspection, the forces in the other portions of the building are acceptable.

4) A comparison of the instructure response spectra curves has been made and indicates that the majority of the floor spectra curves have little or no change. The greatest changes were confined to the structural steel superstructure, ' control tower, and electrical penetration areas at el.674'-6" and above. The frequencies most affected by this change were between 4 and 10 cps. The maximum increase in acceleration occurred at approximately 6 eps and was 1.6 times- the previous spectrum value. In other areas in the building, the new instructure response spectra did not differ significantly from the existing spectra. By inspection, these areas are acceptable.

Witi one exception, piping systems in the area affected were found

- to be acceptable. The. piping systems that were selected for evalua-tion were located in the area where the greatest change in seismic loads occurred and where the pipe or hanger stresses were close to i

a t'-wm-WP' yeT- yg-, +-ve-y- i-W MV@b-"*""="-W=' 4-- - --H--'--*DM- tw'tmW'e='-'T-'-m'hwW"@"'-9r' W bt-"'T1+W7W-+ W -r'*-9-T=w9 W-TTPT"F4'm=*t +4""-r+'Mt=' ' - '9-Jp--7N-9Y h'-Wedv'-f'*--WtW'"*-

Bechtel Associates Professional Corporation MCAR 47 . , . - - e.

Interim Report 3 V O b, U d 0 May 15, 1981 Page:3 the maximum allowable before checking the new seismic stresses.

The auxiliary steam and turbine exhaust vent stack-to the atmos- -

phere is the only system found that will experience substantial

> increases in loadings. The three supports for the.ventLstack will need to be checked for an increase in seismic loads. The potential safety impact of the increased load on the hangers has not been determined.

Equipment systems in the area affected were found to be acceptable.

Equipment was selected to be checked based on its potential for change. The revised spectra were compared to the spectra used to l seismically qualify the equipment, and the equipment still met acceptance criteria.

Corrective Actions Completed

1) During the week ending January 23, 1981, the assumption that the control tower and the main portion of the auxiliary building is a nonintegral unit between el 614' and 659' was incorporated in a modified model of the auxiliary building. Accordingly, this acticn is complete.

2) The structural response analysis has been completed.

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3) The time-history analysis and corresponding in-structure floor response spectra have been generated.

4) A sample of the existing equipment seismic qualification records have been reviewed and found to be adequate for the revised spec-trun.

5) The stability of the structure is not significantly affected; therefore, it has been found to be sat isfactory.

6) The structural steel superstructure has been checked and found to

, be adequate.

Corrective Actions to be Completed

1) Complete the investigation of the structural design in affected 1

areas of t.e structure

2) A sample of the existing piping syster. has been reviewed and potential safety impact on three hangers is being investigated

3) Establish whether this is " reportable" based on results of the investigation described above

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1 Bechtel Associates Professional Corporation j i

MCAR 47

- Interim Report 3 030o93 l I

May 15, 1981 Page 4 Root Cause This omission, the magnituda and implications of which'are still to be determined, was not caused by a failure to follow a procedure. All procedures pertaining to the origination, checking, review, and approval of calculations had been followed.

This omission involves.a subjective technical determination of the most effective way to mathematically'model a physical feature of the structure.

The methods and values used were judged to be appropriate for the east-west direction, but detailed design review revealed that the methods and values used did not adequately represent-the structure in the north-south direction.

Because these parameters are specifically and uniquely determined for each portion of the structure, this omission is believed to be a random occurrence with no generic implications. Therefore, there is no generic or process corrective action planned. To support this point, models used in the analysis of safety-related structures wert visually inspec-ted, and no geometric situation was identified which would lead to a similar model omission in development of beam properties. Due to the

• soils problem and foundation modifications, the other models are being revieweu and will be modified if necessary.

' Other Activities Not Within the Scope of this MCAR lhe scope of this MCAR, which was discussed in the preceding sections, was to define the root cause and conduct an investigation to determine

, the reportability of this situation. The following items are general descriptions of activities that have been previously identified in the

Responses to NRC Requests Regarding Plan *. Fill. These items !.nvolve an

extensive reanalysis which includes changes which will correct the omission identified in this MCAR. These activities will continue to be tracked by that previous effort, and are separate from the MCAR.

1) Continue seismic reanalysis of the auxiliary building considering I the current building configuration (e.g., tornado shield), present soil conditions, and proposed plant fill remedial action (e.g.,

caissons under electrical penetration areas). This analysis will i

incorporate the modified model described in Corrective Action 3

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above.

2) From Item 1 above, develop revised seismic forces, moments, and response spectra.

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Bechtel Associates Professional Corporation MCAR 47 Interim Report 3 030690 May 15, 1981 Page 5

3) Review existing structural designs, piping systems, mechanical systems, control systems, and equipment qualifications for adequacy to revised items listed in Item 2 above. If this action discloses discrepancies, corrective action measures will be implemented.

4) The affected FSAR Figure 3.10-7 has been identified as subject to change at a later date in the Responses to NRC Requests Regarding Plant Fill.

Reportability This subject was reported by Consumers Power Company to the NRC at : po-ti-~'slly reportable 10 CFR 50.55(e) item on January 21, 1981. 7o date, i . . not been established whether this item is " reportable" vr. der the et, .ria of 10 CFR 50.55(e). Reportability will be addressed in subse-quent reports based on the results contained in the section entitled

" Investigation", above.

Prepared by: h D.T. Scrt h r b

Approved by: h < - - _-

N. Swanberg Concurrence by: /-

K!D. 1 ley

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