ML17209A679

NRC IE Bulletin 80-11,Final Rept. Three Walls Require Field Mod.Twenty Walls Require Reinforcement of Top Edge Support.Affidavit Encl

ML17209A679
Person / Time
Site:	Saint Lucie
Issue date:	02/11/1981
From:	EBASCO SERVICES, INC.
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ML17209A678	List: ML17209A677 ML17209A679
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IEB-80-11, NUDOCS 8103030062
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ST LUCIE'L'ANT - UNIT NO. 1 NRC IE BULLETIN 80"11 FINAL REPORT PREPARED BY EBASCO SERVICES INCORPORATED FOR FLORIDA POWER.,& LIGHT COMPANY l

8 03P 30D4

TABLE OP CONTENTS Section Title ~Pa e Introduction II Description of Masonry- Walls III Construction Practices IV Inspection of Masonry Walls Design Verification VI Results of Inspection and Verification 17 VII Summary 20

I. Introduction On May 8, 1980 the NRC issued IE Bulletin 80-11 on the subject of design of masonry walls. Florida Power & Light Company in response, through their architect-engineer, Ebasco Services Incorporated, instituted a field inspect-ion program and design re-evaluation program to verify the adequacy of the exist-ing masonry wall des'ign as requested by the bulletin.

The field inspection program was completed in October, 1980. By then the re-evaluation criteria had been finalized and the analysis portion of the program was underway. The re-evaluation of the walls was essentially com-pleted by the end of December 1980. There remained only the final analysis of a few walls and the investigation of the ceiling attachments for the full>>

height walls. This portion. of. the program was, completed in January 1981.

FPL in its initial response= to Bulletin 80-11 of July 24, 1980 (Ltr L-80-233)addressed items, 1, 2a, and 3 of the bulletin, describing the planned

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inspection and re-evaluation phase's of the program. A"second interim re-sponse of November 4, 1980 (Ltr L-80-374) reported the completion of the field inspection and the development of the re-evaluatioq criteria and requested an extension to February 9, 1981 for submittal of the final report to the NRC.

The following report presents in detail the information requested in item 2.b of Bulletin 80-11. The procedures for the inspection and verification programs are discussed, as well as the results of those programs and correct-ive actions taken.,

EI. Description of Masonry Walls 204 masonry walls were constructed in the Reactor Auxiliary Building and Fuel Handling Building for St Lucie Unit 1. All'he safety-related masonry wal'ls are located in the Reactor Auxiliary Building. The functions of the walls include pressure retention (primarily for maintaining HVAC flow bal-ancing), security, personnel control and shielding for radiation expos-ure reduction. Wall construction included both stacked and running bond types. Where. multiple thicknesses were provided for shielding purposes, the joints. were staggered.

Of the 203 walls in the RAB,. 101 were originally designed for seismic loading.

The-remaining 102 walls in the RAB and one wall in the FHB were not designed for

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seismic loading. The seismically designed walls, were provided with vertical rein-consisting of eight A reinforcing bars, four in each cell, and the 'orcement cells were filled with mortar.. These reinforced units are spaced 4' 0 on centers. "Dur-0-Wal" horizontal truss reinforcement was placed at. every mortar-joint. during erection of the reinforced masonry walls.

The walls not designed, for. seismic loading were provided with reinforcement consisting of "Dur-0-Wal" every third course. These are described as "unre--

inforced walls" elsewhere in this report.

No masonry ties between the wythes were provided for multi-wythe walls.

The materials of construction used were as follows:

Masonry Units -. ASTM C90 Grade N Mortar ASTM C270 Type S Reinforcing Steel. >> ASTM A615 Grade 40 Structural Steel (supporting angles, embedm nts) - ASTM A36 Masonry walls which are in proximity to or have attachments from safety-related piping or equipment such that wall failure could affect a safety-related system are designated as safety-related walls.

3 The inspection program'dentified 90 walls falling into this category. Of these, 65 were reinforced and 25 were unreinforced. All safety-related walls required design verification to establish structural adequacy to carry postulated design loads. The design verification program is described in Section V of this report.

The remaining 114 walls were designated "not safety-related;" no further evaluation of these walls was required.

III. Construction Practices A - Reinforced Block Walls The block walls are supported by a 2.' 0 high concrete starter wall which i:s

~ doweled into the floor slab with number. 6 reinforcing bars on 12 inch centers on each face. The reinforced block wall units, spaced at every 4 feet, re-ceived 8 number 4 reinforcing bars. The positioning cf the reinforcing bars was accomplished by building up the block wall to four courses high then fil'ing the cells with type "S" mortar, rodding the mortar to achieve homogeneity.

Then the 3' 0 long reinforcing bars were inserted into the mortar-filled cells leaving a projection of'Bur inches beyond the blocks.

Eight splice bars were introduced adjacent to the original bars, projecting three feet and. splicing 1' 0 with the initial rebar. Next 'the blocks vere inserted over the projecting reinforcing and built up to four additional courses, continually fi11ing the. cells with mortar and rodding the mortar.

The sequence was repeated unti.l the wall was built, up to within four courses of the ceiling. 'I In order to position the last four courses in such a way that the rein-forcing was continuous to the ceiling, the sidewall of the block was chipped out and the rebar inserted horizontally. The cell was then filled with mortar and the chipped out sidewall of the block repaired with the same mortar.

Horizontal reinforcing (Dur-0-Wal) was placed at every mortar joint during the erection of the block wall.

Horizontal reinforcement splices were staggered vertically so that, no splices in two adjoining courses are less than 8 inches horizontally apart.

Where a multiple thickness wall was required due to shielding considerations the vertical joints were staggered.

B - Unreinforced Block Walls A 3/8" mortar bedding is. provided on.top of the slab and the block is layed on this bedding. ) every third course receives "Dur-0-Wal" horizontal reinforcing.

For partial height walls< that receive a precast slab over them, the last course is a precast bond beam with two,number 5 reinforcing bars (continuous). The.

bond beam is connected to the roof slab by number 4 bars at 3' 4 O.C. The cell is then filled with mortar;.,

Full'eight walls spanning from floor to ceiling received Dur-0-Wal at every third course and a. bond, beam at approximately mid-height and at the top of the wall, with similar re nforcing and, grouting to that provided for the partial.

height walls.

IV. Ins ection of Masonry Walls Pursuant to the requirements of NRC IE Bulletin 80-11 dated May 8, 1980, a field inspection program was developed to "identify all masonry walls in your facility which are in proximity to or have attachments from safety-related pip-ing or equipment such.that wall failure could affect a safety-related system."

In accordance with the Procedure for Inspection of Concrete Masonry Walls, FL0-128-4.800, Rev 3, the field inspection program consisted of two phases.

Phase I. inspection included. a review of the site general arrangement and concrete masonry wall drawings, to determine the extent of the inspection.

A master set of reference drawings showing all masonry walls was assembled and each wall, was assigned a unique identification number. These master reference drawings are marked-up reproducible copies of general arrange-

5 ment drawings, showing wall location and identification and issued under Backfit Change Sketch numbers BCS 128-4.300 thru .304.

An inspection data sheet was prepared (FLO 128-4.800 Att 81) for each wall and the Phase I portion of the sheet completed. This portion included the wall unique identification number and orientation of the wall as shown on the design drawings. Reference was made to the master reference drawing (BCS) showing the wall, and a description of the plant location, including building, floor elevation and reference to major equipment in the. area. In addition, the design function of the wall was listed at this time. These included pressure retaining or primarily for maintaining HVAC flow balancing, security or. partition walls for personnel control and shield walls for radiation exposure reduction. Phase, I work also included a review of the wall design construction drawings and a listing of the thickness and composition of the wall, including reinforcement details and multiple wythe construction.

ll Upon completion of, the Phase I portion of the inspection data sheets, the field inspection program or Phase II portion was implemented.

Inspectors performing Phase II field inspections were Ebasco design or engineering personnel, familiar with, power plant operation and safety-related equipment identification. The inspectors were briefed. documented, certified, in accordance with Inspection Procedure FLO 128-4.800.

The Phase II field inspection consisted of locating each wall identified on the master reference drawings. After location of each wall., an inspection was made with a James Electronics R-Meter, to verify the existence of vertical reinforcing rebar and/or horizontal reinforcing Dur-O-Wal, if called for in the design construction drawings. This inspection was a sampling verif-ication to determine the existence of at least one vertical reinforced rebar column and. two horizontal reinforced Dur-0-Wal joints. After fur'ther field

verification of wall thickness and composition (where verifiable), the appro- -.

priate section of the inspection data sheet was checked.

r 6-Following this, an inspection of each wall was made to determine if there was any safety-related equipment mounted or in close proximity of the wall. This equipment included, but was not limited to, safety-related piping and supports, conduit, cables, electrical boxes, pumps, heat exchangers and instrumentation.

For the purpose of this inspection, "close proximity" was defined as: i) a dis-tance equal to approximately. five (5) feet for reinforced and un-reinforced full height walls or, ii) a distance equal to the height plus one (1) foot for cantilevered reinforced walls. This, distance was measured as a perpendicular distance from the wal'o the safety-related equipment.

Upon the determination that no safety-related equipment was attached, or in close proximity to a wall, the inspection data sheet was marked "not Safety-Related" and signed off, with no further verification required. If any safety-.

related equipment was identified, a sketch of the wall was made, locating all safety-related and- significant non-safety related equipment loads on the wall..

"Significant," as used in this inspection, was defined as any equipment which in the very conservative judgement of the engineers performing the inspection contributed a load. to the masonry wall greater than twenty-five (25) pounds per square foot wall surface. In addition, all wall penetrations for HVAC, electrical, cable trays, ductwork and grill penetrations were shown on the wall sketch. All loads having a center of gravity greater than one foot from the wall surface were noted, as well as any general observations by the inspector con-cerning the "as-built" condition of the wall.

Since the intent. of Bulletin 80-11 is to identify equipment affected should a wall failure occur, a .detailed list of safety-related equipment in proximity to a wall was developed for walls for which an engineering evaluation might show failure under- certain po tulated load conditions.

Upon completion of the inspection data sheets, copies were transmitted to the Ebasco NYO Lead Civil Engineer for review, in accordance with "Uerification of Concrete Masonry Wall Design" Procedure FLO 128-4.802. During this review, and at the request of the lead Civil Engineer, an additional inspection was made of twenty-four (24) of-the masonry walls.- For this inspection, two (2) one-half

'

inch holes were drilled into the cells of the selected block walls t'o verify

7 the existence of the grout or mortar fill.

In addition to the field inspections performed at the site to verify the "as-.

built"condition of concrete masonry walls, several Quality Assurance audits-were performed in accordance with the "Quality Assurance Procedure for Compli-.

.ance with NRC Bulletin 80-11" FLO 128-4.801. These audits of the Phase I and.

Phase -II portions of the inspection were performed jointly by FPL and Ebasco and included verification of inspector training,. data collection and docu<<

mentation of findings.

V. Desien Verification Masonry walls identified by the field inspection program as safety-related, i.e. having safety-related equipment mounted on the wall or located in the vicinity of the wall such that it could be damaged by possible wall fail-I ure, required a design re-evaluation to demonstrate their capacity to withstand, postulated design loads. A design verification program 'for this purpose was- conducted in accordance with Procedure 128-4.802, "Procedure fo- Verification of Concrete Y~sonry Mall Design."

The masonry walls are not shear resistant elements in the building struct-ure system, nor load bearing walls.. They primarily function as shielding and partition walls except in one case as'a pressure boundary. Therefore, the primary concern of the masonry wall re-evaluation was focused on the behavior of the masonry walls in the event of the safe shutdown earth-quake.

A. Loads and Load Combinations The loads that are imposed on the masonry walls are:

1) Dead Load (D) - This includes the weight of the wall and structures or equipment supported by the wall, The attachment loads are con-duits, small pipes, junction boxes, switches and transformers.

2) Seismic Loads

, a) Feqo - This is the load generated by the operating basis earth-quake (OBE) specified for the site of the plant and developed for the wall by the seismic analyses of the building. The seismic accel-erations are applied to the mass of the wall and all attached equip-ment. In-plane and out-of-plane loadings and the, effects of inter-story drift of walls are considered.

b) Feqs - This is the'load generated by the safe shutdown earthquake (SSE) specified for the site of the plant, and developed as described above for OBE.

3) Pressure Load (Pa) - This is the pressure equivalent static load within the masonry wall compartment caused by failure of equipment. The load includes an appropriate dynamic load factor determined by analysis.

Since all walls are located indoors, there are no wind or tornado loads'he walls are not, subjected to pipe rupture reaction loads.

There are three possible load combinations when combining the above four (4) different individual loads:

Allowable Stresses

1) Severe Environmental Condition = D+OBE S (Table 1)

2) Extreme Environmental Condition = D + SSE U (Table 2)

3) Abnormal Extreme Environmental Condi- = D + SSE + Pa U (Table 2) tion Since the allowable stresses used for combination (2) are in general only 1.67 times those used for combination (1)., while the SSE loading is twice the OBE loading, load combination (1) is not governing.

The postulated load combinations are consistent with the FSAR commitments.

Since the -FSAR does not specify allowable stresses to be used for design of masonry walls, the allowable stresses listed in Tables 1 and 2 are based on ACE 531-79,, "Building Code Requirements for Concrete Masonry Structures."

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Table 1: Allowable Stresses in Unreinforced Masonry Description Allowable Maximum owao e xxmum (psi) (psi) (psi) (psi)

Compressiye)

Axial 0'.22f ' 1000 0.44f' 2000 Flexural 0.33f ' 1200 0.85f' 3000 Bearing On Full area 0.25f m 900 0.62f'm 2250 On one-third area or less 0.375f '. 1200 0.95f ' 3000 Shear Flexural members 2, 3) l. l 50 1.7 75.

~f'.9 Jf'.35Jf' Shear Walls C2) 34 51 Tension ~f'.

Normal to bed joints Hollow units 25 0.83 J m 62 5~m'.0J Solid or grouted m 40 1.67~m Parallel to. bed joints (4)

'.0 67'34 Hollow units ~m. 50 1. 67~m 0 0

Solid or grouted 1.5/ m 0

80 2. 5~m Grout Core 2.5 J~ 4.2 JY Collar joints Shear 12 Tens ion Notes to Table 1:.

(1) These values should be- multiplied hy (1 - (&i)3.)if the wall has a significant vertical load

'I (2) Use net bedded area with these stresses.

(3) For stacked bond construction use two-thirds of the values specified.

(4) For stacked bond, construction use. two-thirds'f the values specified for tension normal to the bed joints in the head joints of stacked bond construction.

(5) Note: For St Lucie Unit 81, m = 1800 psi f'm 900 psi

~ ~

10-Table 2: Allowable Stresses in Reinforced Masonry Description Allowable Maximum llowable Maximum si sil si si)

Compressive Axial.(1) 0.22f ' 1000 .44f ' 2000 Flexural 0.33f ' 1200 .85f' 2400 C

Bearing On full area 0.25f'.375f 900 62fm 1800 On one-third area ' 1200 .95f' 2400 or less Shear Flexural members (2) 1.1 ~f' 50 .7

'Shear Halls'3, 4)

Masonry Takes Shear ~f'5A'4~f M/Vd > 1 9~f' 56 M/Vd = 0 123 Reinforcement Takes 2.0Jf'.5~f Shear M/Vd> 1 75 2.5 ~f' 125 M/Vd= 0 2.0~ 120 180 Reinforcement Bond Plain Bars 60 80 Deformed Bars 140 186 Tension Grade 40 20,000 0.9F

! Grade 60 '4,000 0.9F I

Joint h'ire .5F or 30,000 0.9F I

Compression 0.4F I 0.9F V

P h Notes to Table 2:

h (1) These values should be multiplied by (1- (40t) )

3 if the wall has a sign-ificant vertical load.

(2) This stress should be evaluated using the effective area shown in figure below except as noted'n (6).

6t ot

~Mr $ 04cln9 n ehe e n lees lnr tvnniny bond II i ~v/ r<<'rr ~rrrrrrrrrrrrrrrrs>><<~>>r~

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~

~ ~

~

~

' ~

~

~ ~ ~

Aces taumcd t<<~ive in lltxvrsi comota)ion furca normal <o tact (3) Net bedded area shall be used'ith these stresses.

(4) For H/Vd. val'ues between 0 and 1 interpolate between the values g'ven for 0 and l.

(5) 'ote: For St Lucie Unit /PI. m 0

~ 1800 psi f' 900 psi (6) If Dur-0-Wal reinforcement is provided for stack bond walls the effective width of the reinforced uni.ts can be 'increased to the same amount-as that used .for running bond walls.

12 B. Analytical Model All masonry waLls were transformed into equivalent homogeneous plate elements spanning vertically to resist out-of-plane bending loads. For reinforced masonry walls, the top support was assumed to be simply supported, since the walls are restrained by two clip angles on'both sides. The bottom support was assumed to be fixed because dowels inside the walls can transfer bending moments to the starter walls. The effective width of each reinforced unit is a little less than the spacing of the- reinforcing units for the stack bond ~-

walls according to ACT-531-79. However, DUR-0-MAL reinforcement was provided for every course, and cement mortar is filled in the cell cores of all blocks so that the entire width of, the wall was considered effective for the model.

For unreinforced walls, the simply supported condition was assumed for both top and bottom supports. Rigid arching was also assumed when arching analysis was performed, since no gap-was detected- at the top support during inspection.

(See figure'1; and, 2)

A Finite element models were used to represent the masonry walls. All large openings were included in the model. The weights of attachments were input as mass for frequency analysis. All of the attachments except transformers are rigidly connected to the walls with the center of mass less than a foot from the wall surface. Also the maximum weight ef the attachment is less than 1%

of the total weight of the masonry wall 'itself. Therefore, dynamic amplification

'f the attachments was not considered, except in the case of the transformers, where an independent dynamic analysis was performed. The AHSYS computer pro-gram was used for all the analyses.,

Tha. analysis of multi-wythe walls does not assume composite action between the wythes.

13 15 16 Fly; 'L Qe~ lllestretfay tae.Nffereaces $a Notfoa Seteeea Rfyfd ead Cspped ArcMay.

17

\8 2'1 25 Ik ma p lip

).

31 5A 32 33 34 35 Ay, 2. Ftae lodF Neyreas Shoetay Forces 1a 81yfd ead Oapped Archway.

36

C. Dynamic and Static Analyses The frequency analysis of the masonry wall is the same as for ordinary plate elements except that both uncracked and cracked sections are con-sidered for the reinforced masonry walls. The critical damping values used in generation of floor, response spectra for SSE were 7% for reinforced cracked walls ano 2% for- uncracked walls (both reinforced and unreinforced). Seismic acceleration values were selected from the floor response spectrum at the bottom of the wall or the floor response spectrum at the higher elevation, whichever yielded the maximum response at the predetermined frequency., A I

25% variation of the frequency range was also considered due to'variations of masonry material and other factors.

All the loadings including dead weight of, the masonry wall, attachment loads and seismic, loads (horizontal and vertical) were input into the computer.

The output stresses were compared with the allowable stresses list d 'n Tables 1 and, 2.

D. Special Analyses Since the re-evaluation. of the masonry walls is based on, the assurance of "no collapse." of the walls for the most critical load combination, if the flexural. stresses exceeded the design allowables at one section of the wall, the wall is still not necessarily considered to fails Two special analysis techniques were used to evaluate this type of situation. The "Yield-Line Theory" or "Plastic Design" was used for the reinforced masonry walls; whi.le the. "Arching 'Analysis" was utilized for the unreinforced masonry walls.

1) Yield Line Theory - As stated above, in the analyt'cal model the re-inforced masonry wall was assumed fixed at the. bottom and simply supported at the top. This is considered an indeterminate structure. Therefore, a line of hinges was inserted in the model where the flexural. stresses at that -location exceeded the allowable. The bending moment was then re-distributed by re-analysis of the. wall. lf the resulting bending stresses

15-D. 'pecial Analyses (Cont'd) were found to be acceptable at all other locations and.the displacements

-

were not excessive; the wall was considered to be qualified.

2) Arching Analysis - The behavior of a cracked unreinforced wall may be considered as that'f a 3-hinged arch with hinges formed at midspan, top and bottom supports. If a gap exists at the top of the wall, gapped arching action, should be assumed; otherwise, rigid ar'ching action is assumed as illustrated in Figure 1. The reactions for the 3-hinged arch can be solved by means of the free-body diagrams shown in Figure 2.

E. Interstory Drift Although the S" Lucie. Unit 1 concrete masonry walls- are not intended to carry a significant part of the. building story shear,, in-plane shear may be imposed on them by the relative displacement between floors during seismic events., The strain acceptance criteria was used for evaluation of in-plane interstory drift. The relative displacement between floors -ncludes two types of dis-placements. One is due to bending deformation of the structural shear walls; the other is due to shear deformation. The bending deformation of the struct-ural shear walls will only cause the masonry, walls to elongate or shorten on the sides. It is the, shearing deformation of the structural shear walls be-tween floors which will cause the masonry walls to have in-plane shearing strain effects. It is these strains which are evaluated as described below:

The gross shear strain is defined- to be:

r strain Where 5 =,

= relative displacement between top and bottom of wall H = height of wall The permissible in-plane shearing strains are:

16-E. Interstory Drift (Cont'd) u

= 0.0001 for unconfined walls ~

c

= 0. 001. for confined walls-The above val'ues were used for normal and severe environmental load combin-ations. For other load combinations, the allowable strains were multiplied by 1.67.

+ An unconfined wall is attached on one vertical boundary and its base. 'A confined wall is attached, in one of the follow'ing ways: (a) on all four sides; (b) on the top and bottom of the wall; (c) on the top, bottom and one vertical side of. the wall; (d) on the bottom and two vertical sides of the wall.

f The out-of-plane interstorv drift. of the wall due to differential displace-ments between the two floors will not be significant. due to the following reasons:

If the k

1) wall. is simply supported at the top and bottom, the same bending moment capacity will remain after considering the out-of-plane drift effects.

2) If the wall is fixed at the bottom and simply supported at the top, the

.out-of-plane drift effects 'will cause at most the fixed end support to yield. The maximum bending moment capacity of the wall will remain the same.

Therefore, the out-of-plane drift effects were not. input into the computer analysis.

Several Quality Assurance audits of the. design verification work were performed in accordance with Procedure FLO 128-4.801, "Quality Assurance Procedure for Compliance with NRC Bulletin 80-.11." The audits were performed by Ebasco and FPL Quality Assurance personnel.

17 VI. Results of Ins ection and Desi n- Verification A - Inspection The initial Phase, I and Phase II inspection program (described in Section IV of this report) was completed in early October. 1980. The inspection included 204 masonry walls, of which .90 were identified as safety-related.

In .the course of this inspection, 14 safety-related walls were found to be missing the top support angles called for in the original design. It was decided to immediately install the angles to bring the walls to the original design con-figuration without- first performing an analysis to determine whether in fact wall failure would occur without the top support. Subsequently it was deter-mined that the structural'. integrity of the walls during a seismic event could not be demonstrated without ass~ing the presence ot the angles. One -wall side (inaccessible during plant operation), will be repaired during the 1981 refueling outage. This wall. cannot .fail in such a way as to affect safety related ecpxxpment.

A supplementary inspection was conducted for those safety-related walls where the complexity of the attachment configurations indicated the need for a more precise definition of loading application on the wall in order to obtain a more representative analytical model. This portion of the. inspection program

'was 'completed in, late October 1980.

Many masonry walls shown on design drawings as unreinforced nevertheless had cells filled. with mortar or grout for radiation shielding purposes. During the course of the design re-evaluation, it became necessary to determine whether some unreinforced walls did in fact have filled cells. An additional inspection of .24 walls was conducted in mid-December 1980 to verify the presence of cell mortar, as described, in Section IV of this report. 13 of the walls were found to contain mortar in their cells and this fact was incorporated into the analysis. All the unreinforced'alls were ultimately qualified by analysis except wall 114, which required modification as described below.

0 18-B - Design Verification The analyticaL effort to verify the design adequacy of the 90 safety-related masonry walls began in October 1980 with the issuance of the re-evaluation criteria, By this time, most of the field inspection data had been received.

EvaLuation of the masonry wall designs was completed in December 1980; and the evaluation of the top supports and anchorages was completed in January 1981.

At the end of December 1980, 6 safety-related walls remained which appeared to not satisfy the established re-evaluation criteria. A final inspection of these walls was conducted on January 6 and 7,. 1981 to explore feasible methods of strengthening the walls. It was established, that apparent cracks in two of the walls were facial only and not stress related. Repair was accomplished by enl'arging 'the cracks and filling in with mortar. The pre-sence of reinforcing in a third waLL was confirmed and a new analysis re-suited. in qualification of that ~aLL.,

The remaining, 3 walls- were deemed to require modification as described below:

1. Wall 114 - The analysis of this unreinforced wall resulted in unaccept-ably large compressive and shear stresses. The height of the wall was re-duced to 60 percent of its originally assumed. value by the introduction of a.

supporting structural member acting. 'n concert with a slab framing into the wall at the same elevation. A new analysis resulted in qualification of the wall. as modified.

2~ Mall 159 - An excessive number of'arge opening in this reinforced wall prevent the vertical. reinforcing bars from running all the way through.

The analyticaL model was revised with the add'tion of supporting angles to the vertical edges of the lower half of the wall, fastened to the adjacent reinforced concrete column or wall. The additional supports resulted in the qualification of. the wall.

19

3. Mall 203 - This wall had the same problems Wall 159. In addition, part of the top supporting angle was missing due to blocked access from ductwork. A fix was developed similar to that provided for Wall 159, to be applied along one vertical edge of the wall. A supporting channel pair was added along the top edge where required, to be bolted into the ceiling wnere access .permitted. A stiffening channel pair extending from the top channels down to a more substantial area of the wall pro-vides support. for the remainder of the top edge. A new analysis re-sulted in qualification of the wall as modified.

All wall attachments were analyzed locally for block pullout, as well as being integrated into the overall analytical model for the wall. No stress problems arose in this area. One bracket-type support for a transformer required an independent analysis to determine the dynamic amplification imposed. on the wall.

As the stress analyses for the walls were completed, .the reactions at the tops of the walls were used'o evaluate the adequacy of the supporting ang'es and anchorages where these were provided. A review of the design details indicated that, for 20 walls, the supporting angle attachment to the building structure had to be modified to accommodate the calculated reactions.

The following table explains the modifications to the top supports:

Wall Number Descriation of Modification Addition of clip angles expansion anchored to ceiling 1lA Addition. of clip angle expansion anchored to ceiling and plate welded to ceiling embedment 34, 74, 125 Addition of expansion anchors for clip angle 165, 200, 201 support 202, 205

Wall Number Descri tion of Modification 62A Addition of clip angles, filler plate welded to ceiling embedded plate 80, 123, 124 Thru-bolting clip angles on either side of wall 81, 82, 163, 174 Thru<<bolting clip angles on either side of wall, Add'ition of expansion anchors for clip angle support 160 Addition of expansion anchors for clip angle support Addition of mortar to enable block wall to bear on adjacent concrete beam 166 Addition of fillet weld between clip angle and filler plate VII. Summarv The. inspection and design verification of masonry wall:; for St Lucie Unit

1. conducted between September 1980 and January '981 established the follow-ing:

Number of walls inspected -- 204 Number of. walls classified as safety-related - 90 Number of walls classified as not safety-related - 114 safety-related walls where missing clip angles were replaced -

'f Number 14+

Number of safety-related walls re-evaluated - 90 Number of walls requiring. field modification - 3 Number of walls requiring reinforcement of top edge support - 20 Documentation, to include inspection procedures and design verification details will be available at the St. Lucie site for inspection and review and has not been attached to this report.,

• Further clip angle work. is required for 1 wall to bring it to original design+

0 0 STATE OF FLORIDA )

) SS ~

COUNTY OF DADE )

Robert E. Uhrig, being first duly sworn, deposes and says:

That he is a Vice President of Florida Power 6 Light Company, the Licensee herein; That he has executed the foregoing document; that the state-ments made in this said document are true and correct. to the best of his knowledge, information, and, belief, and that he is authorized to execute the document on behalf of said Licensee.

Robert E. Uhrig Subscribed and sworn to before me this '

I ji day ot i9 K(

4 ~

~

NOTARY PUBLIC in and for the county of Dade, State of Florida Notary Public. State of Rorida at Large My Commission Expires October 30, 1983

~

Ny commission expires: