ML20040B715

Forwards re-evaluation of Concrete Masonry Walls,In Response to IE Bulletin 80-11.Also Forwards Survey Procedure for Concrete Masonry Walls in Category I Bldgs, Procedures 9645-A-004.2 & 9645-A-004.3 & Related Documents

ML20040B715
Person / Time
Site:	Grand Gulf
Issue date:	01/19/1982
From:	Dale L MISSISSIPPI POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20040B716	List: ML20040B715 ML20040B725 ML20040B732 ML20040B741 ML20040B743
References
REF-SSINS-6820 AECM-82-29, IEB-80-11, NUDOCS 8201260348
Download: ML20040B715 (11)

Text

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MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. BOX 16 4 0. J A C K S O N , MISSISSIPPI 39205 U,"', N January 19, 1982 s @-g g# '; ' ,' 3 74Uf,1 E A H Pho(N JCitote id I' A HIDM P4I

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U.S. Nuclear Regulatory Commission C. ,p Office of Nuclear Reactor Regulation ^ C ' '

Washington, D.C. 20555

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l Attention: f! r . liarold R. Denton, Director N.~/, ,

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Dear f!r. Denton:

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SUlUECT: Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416 and 50-417 File 0260/0217/L-860.0 IE Bulletin 80-11, Category I tlasonry Walls Reference AECt!-80/206 AECt!-82/29 Fli s s . s s i pp i power & Light's (FIP&L) letter, AECt!-80/206, was our response to your request of Apri1 21, 1980, entitled "Information Request on Category I flasonry Walls Employed by Plants under CP and OL Review."

Subsequent to the issuance of the NRC's information request on Category I masonry walls, IE Bulletin 80-11 was issued. Although this bulletin applies only to power reactor facilities with an Operating License, we initiated a re-evaluation of concrete masonry walls in Category I structures at Grand Gulf. To date, the following work has been completed:

1. A comprehensive field survey was carmiacted between November 1980, and Janua ry 1981. N s survey identified all safety-related items attached to or 1, ited in proximity to masonry walls at that time. In add;ttur., data was recorded to determine the wall geometry, location of penetrations and type of closures, location and magnitude of attachment loads, type of wall support, and any additional information which could affeet the structural int egrity of the walls.

2. I!pon completion of the survey, the information obtained was used to re-evaluate the ability of these walls to perform QQ [

their intended functions during all postulated loadings, V without impairing the integrity of Category I systems and 5 components attached to or in proximity to these walls.

Criteria were generated for the re-evaluation, which consider I /

present state-of-the-art analysis and design techniques, as well as licensing commitments contained in the FSAR.

3. Any masonry walls which did not conform with the criteria were modified as required, and appropriate design drawings were issued to implement these modifications.

8201260348 820119 PDR ADOCK 05000416 G PDR 1 ember Middle South Utilities System

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AECrl-82/29 MICSISSIPPI POWER & LIGHT COMPANY Page 2 During the fall of 1981, a second field survey was initiated. The purpose of this survey was to identify any additional wall attachments or changes in wall configurations subsequent to the first survey. The walls were then re-evaluated as necessary, and modification designs, if required, were issued.

Attachment I constitutes our formal report on the re-evaluation of concrete masonry walls at Grand Gulf. This report contains all information requested in IE Bulletin 80-11, as well as a comparison of the Grand Gulf masonry wall design criteria with Revision 1 of the NRC's

'3E!! Interim Criteria for Safety Related ?!asonry Wall Evaluation" (July 1981). As further substantiated in Appendix D of Attachment 1, ali concrete masonry unit (CflU) walls, either as constructed or as i modified, satisfy the SEB Interim Criteria load combinations and allowable stresses.

Pfodifications determined to be required based on our CtlU wall review will be completed prior to restart after the first regularly scheduled refueling outage.

This completes our response on IE Bulletin 80-11. If you have any questions, please advise.

Yours truly,

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.; C.b' Y L. F. Dale

,. 11anager of Nuclear Services DDW/Silli/JDR:Im

, Attachment i

a cc: tir. N. L. Stampley (w/a) fir. G. B. Taylor (w/a) 1 t!r. R. B. ficGehee (w/a) fir. T. B. Conner (w/a)

, tir. Richard C. DeYoung, Director (w/a)

Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Dr. Franz Schauer, Chief (w/a)

Structural Engineering Branch Nuclear Regulatory Commission Washington, D.C. 20555 AE5J2

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W REPORT ON THE RE-EVALUATION OF CONCRETE MASONRY WALLS IN RESPONSE TO NRC IE BULLETIN 80-11 FOR THE GRAND GULF NUGLEAR PLANT O

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Attachment 1 i

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TABLE OF CONTETTS 1.0 General 2.0 Description of asonry Walls 3.0 Construction Practices 4.0 Re-evaluation Criteria and Co=centary 5.0 Results of Evaluation 6.0 Modifications 7.0 Conclusions 8.0 Planned Future Actions t

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, Attachment I l i l l APPENDICES -  !

i i, A- Survey Procedure for Concrete Masonry Wells in Category I Buildings i l

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i B- Design Criteria for the Re-evaluation of Concrete Masonry Walls in i Category I Structures i

l C- Con:mentary on Criteria for the Re-evaluation of Concrete Masonry  !

Walls i - D- Comparison of Grand Gulf CMU Wall Design Criteria with Revision 1  ;

i of NRC's "SEB Interim Criteria for Safety Related Masonej Wall i Evaluation" (July 1981) {

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E- Architectural Specifications l i

l F- Floor Plan Locations of Masonry Walls'  !

i t G- Wall Configuration and Function Su==ary f l Table I - Control Building Walls i Table II - Auxiliary Building Walls

] H- Masonry, Reinforcement, and Lintel Details 1- Modification Design Examples {

{ J- Block Wall Program Manual l i

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] 1.0 GENERAL 2

' l This report contains the results of the re-evaluation of concrete  !

masonry walls for the Grand Gulf Nuclear Station and serves as a  !

complete response to the NRC's "SEB Interim Criteria for Safety l Pelated Masonry Wall Evaluation" and IE Bulletin 80-11 dated May 8, ,

1980. Walls in the Control Building (Units 1 & 2), and the

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l Auxiliary Building (Unit 1 only) were evaluated. No concrete t j masonry walls were constructed in the Containment or Diesel Ge:wrator Buildings, or in the Standby Service Water Cooling Tower

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2.0 DESCRIPTION

OF MASONRY WALLS [

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j 2.1 - Identification and Function of Walls j Concrete masonry walls are referenced by elevation number (shown on Architectural design drawings) and by survey number (see Appendix A

" Survey Procedure for Concrete Masonry Walls," Paragraph 3.0 for survey i numbering method). Wall Jocations are shown on Architectural design  !

! drawings (see Appendix F for floor plan locations). Two field surveys  !

(January 1981 and October 1981) were conducted to identify walls with  ;

) safety-related items attached or which are located in proximity to  !

safety-related systems or equipment. A summary which includes wall .

j dimensions, section properties andlwall function is tabulated in f

l Appendix C. '

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f All concrete masonry walls within the scope of the survey are internal boundary / partition walls located in the Control and Auxiliary Buildings.

Forty-four walls in the Control Building are load bearing walls i

) supporting intermediate reinforced concrete slabs; all other walls are l non-load bearing. None of the Control or Auxiliary Building masonry  ;

walls are subjected to thermal, missile impact, postulated pipe break, e pipe whip, or jet impingement forces. All are designed to resist  !

t tornado depressurization loads. A secondary function of these walls is  ;

to provide support for relatively lightweight equipment including small piping, conduit, in'strumentation lines and electrical, communication and l' i

fire protection panels.

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2.2 - Wall Configuration and Details j t

l All masonry walls are single or multi-wythe units laid in a running bond 7 pattern. Each wall is constructed of lightweight, load bearing concrete l 3 masonry blocks with widths of 4", 8" or 12". In the Auxiliary Building.

' l 3/16" x #9 ga. heavy duty horizontal reinforcement is placed in every i bed joint for single wythe walls and in every other bed joint for  !

, multi-wythe walls. In the Control Building, the same type of horizontal

reinforcement is provided at every course for all vertically reinforced ,

valls and at every other course for remaining walls. Walls at Elev. i 111'-0" of the Control Building use bond beams with two #4 horizontal bars in every other course in lieu of the reinforcement described

above.

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l Vertical reinforcement for Auxiliary Building walls consists of two #5 i

bars at 8" 0.C. with all masonry cells filled with grout. Two f5 vertical bars at 16" 0.C. are used for typical valls in the Control Building and alternate cells are filled with grout. All vertical reinforcement is lapped with #5 dowels embedded in the supporting floor slab with epoxy grout.

Lintels are used above penetrations where required by design. Typical  !

. lintel types included steel plates, channels and bond beams.  !

The top of each wall designed to span vertically is supported by structural angles or tube steel members. Top supports are connected to

' structural steel beams or main concrete slabs and are designed to allow for dif ferential vertical slab displacements. Top supports are not required for walls designed to span horizontally, but nevertheless are generally provided. (See Appendix H for typical masonry, reinforcement t and lintel details, and boundary conditions.) -

t 2.3 - Materials of Construction -

2.3.1 Masonry Units - Concrete masonry units are either two-core standard, three-core standard, or two-core open end types. Each is Grade N-1, hollow, lightweight, load bearing and has a uniform color, texture and finish conforming to ASTM C-90.

2.3.2 Reinforcement - Horizontal joint reinforcement is Ladur type manuf actured by Dur-0-Wall. It is fabricated from 3/16" diameter longitudinal rods and #9 gauge cross rods conforming to ASTM A82 and has a yield strength of 70 ksi. Horizontal bond beam reinforcement, vertical reinforcement, and vertical dowels are all Grade 60 reinforcing bars meeting the requirements of ASTM A615.

2.3.2 Grout and Mortar - Grout used to fill masonry cells and .

mortar (Type M or Type PL) used at joints have minimum 28 day

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compressive strengths of 2500 psi. Type M mortar conforms to the i requirements of ASTM C 270 and Type PL eortar and core grout each conform to ASTM C 476.

3.0 CONSTRUCTION PRACTICES -

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! I All block walls were constructed in accordance with the requirements of \

Specification 9645-A-004.2 " Furnish, Delivery, and Erection of Concrete '

Masonry Units," Paragraph 8.0 Field inspection practices were governed '

by Paragraph 11.0 of the same specification. Attachments of Q-systems , x; and equipment to CMU walls are documented and shown on design drawings.

' All other attachments conform to the requirements set forth in '

Specification 9645-A-004.3 " Procedures Governing Concrete Masonry Unit Wall Attachments for Non-Category I, Non-Seismic Installations." '(See , '

Appendix E for Specifications 9645-A-004.2 and 9645-A-004.3.) "3

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i 4.0 RE-EVALUATION CRITERIA _AND C0!!MENTARY 4.1 -Criteria Appendix B contains the criteria used for the re-evaluation of the cricrete masonry walls with safety related systems or equipment attached to or in prcximity to the walls in Category 1 structures. Appendix D compares the Grand Gulf masonry wall design criteria with the NRC SEB Interim Criteria and concludes that GGNS and SEB criteria are or will be satisfied

) by Ct!U walls at GGNS.

Licensing commitments contained in the Final Safety Analysis Report (FSAR) as related to loads and load combinations are incorporated

. in the criteria. In addition, the criteria considers present day state-of-the-art analysis and design techniques as follows:

4.1.1 Stress Criteria '

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a. Consideration of cracking for frequency determinations

b. Recognition of potential plane of weakness at the collar joint.

c. Stress increase factors for abnormal and extreme i environmental loa 4s.

d. Realistic damping values

e. Interstory drift F. Frequency variationr due to uncertainties in material properties and effective mass.

4.2 -Commentary on the Criteria

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Appendix C is the commentary on the criteria and contains detailed justification of the criteria by reference to existing codes, test data and standards of practice.

4.3 -Loading Considerations e

' * = The concrete masonry walls in the Control and Auxiliary Buildings were analyzed subject to the loading combinations listed in Appendix B, " Design Criteria for Concrete Masonry Walls la Category I St ructuras. " 'The following is a consideration of the applicability of each design lodd:

1) There are no exterior masonry walls; therefore no walls are exposed to wind loads.

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2) -Thermal loads are not applicable because there is no equipment or piping causing large temperature differentials on or in the proximity of the walls in the Control and Auxiliary Buildings.

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i The locations of.high energy piping is such that loads due 4

3) j to postulated pipe breaks do not i= pose additional forces on masonry walls.

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Because of the above considerations, dead load, attachment loads, seismic accelerations and tornado depressurization are the only forces acting on the masonry walls.

" 5.0 RESULTS OF EVALUATION A Bechtel survey team performed two detailed walkdowns per the " Survey Procedure for Concrete Masonry Walls" (see Appendix A) . Walkdown data (as-built sketches showing wall configuration, penetrations and I

attachments) was used in the analysis of the concrete masonry walls and l served as a basis for wall support modifications. As-built wall elevations showing all penetrations and wall support steel were prepared

, after the modification designs were completed. All wall penetrations and attachments subsequent to the second survey have required project engineering approval.

A total of 246 walls in the Control Building and 42 in the Auxiliary Building were surveyed and are listed in Table I & II of Appendix G.

I Masonry walls were considered accep' table only ~when stresses did not exceed the allowable stresses permitted by the evaluation criteria. -

Where necessary, modifications were designed to insure that stresses remained below allowables.

Intersjory drif t ef fects were considered in the analysis. The differential seismic deflections and the related masonry wall strains were found to result in very small stresses, and therefore, have no adverse effect on vall integrity.

All walls with safety-related equipment attached or in proximity were designed to resist SSE loadings. All other walls were required only to withstand UBC earthquake loadings.

Based on the results of the evaluation, a total of 67 walls in the Control Building and 13 valls in the Auxiliary Building required some type of modification.

6.0 MODIFICATIONS A typical masonry wall modification involved adding external support steel to reduce the horizontal span of the wall. Wide flange columns were normally provided to act as support points and utilize wall strength in the horizontal direction. An alternate modification approach was to provide horizontal support steel (usually WF beams, tube steel or channels) to reduce the vertical span of the wall. In addition, occasional strengthaning of existing wall support steel was necessary to permit the steel to carry attach =ent loads not present at the time of the original design.

7.0 CONCLUSION

S Based on the re-evaluation performed in accordance with the requirements of IE Bulletin 80-11, and the implementation of structural modi fications where needed, it is ccncluded that the concrete masonry walls will meet the SEB Interim Criteria and perform their intended functions. Therefore, the function of Category I systems and components attached or in proximity to the walls will not be impaired.

0.0 PLANNED FUTURE ACTIONS Outstanding items still to be completed at a future date to provide a final response to NRC IE Bulletin 80-11 include:

1) Survey and evaluation of Unit 2 Auxiliary Building CMU walls.

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