ML20115A382

Masonry Wall Design,Brunswick Steam Electric Plant Units 1 & 2, Interim Technical Evaluation Rept

ML20115A382
Person / Time
Site:	Brunswick
Issue date:	11/16/1984
From:	Le A CALSPAN CORP.
To:	NRC
Shared Package
ML20115A385	List: ML20115A382 ML20116P172
References
CON-NRC-03-81-130 TAC-42876, TAC-42877, TER-C5506-245, NUDOCS 8411210300
Download: ML20115A382 (28)

Text

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I ATTACHMENT 1 TECHNICAL EVALUATIO'N REPORT I

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MASONRY WALL DESIGN f'

CAROLINA POWER AND LIGHT COMPANY t

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BRUNSWICK STEAM ELECTRIC PLANT UNITS 1 AND 2 5'

NRC DOCKET NO. 50-325, 50-324 FRC PROJECT C5606 NRC TAC NO. 40876, 42S77 FRC ASSIGNMENT 8

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NRC CONTRACT NO. NRC43 81 130 FRC TASK 245 Preparedby Franklin Research Center Author:

A. K. Le, V. N. Con 20th and Race Street Philadelphia, PA 19103 FRC Group Leader:

V. N. Con Prepared for Nuclear Regulatory Commission

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Washington, D C. 20556 Lead NRC Engineer: N. C. Chokshi'

.c November 16, 1984

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This report was prepared as an account of work sponsored by an agency of the United States Govemment. Neither tf* United States Govemment nor any agency thereof, or any of their

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omployees. makes any warranty, expressed or I,wp!!M, or assumes any legal liability.or respono6tnlity for any third party's use, or the results of such use, of any informst6on, appa-ratus, product er process disclosed in this report, or represents th3t its use by such third party would not infringe privately owned rights.

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j 7RANKUN RESEARCH CENTER l

otvisaoM OF ARVIN/CALSPAN MA

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TECHNICAL EVALUATION REPORT MASONRY WALL DESIGN I

CAROLINA POWER AND LIGHT COMPANY a

BRUNSWICK STEAM ELECTRIC PLANT UNITS 1 AND 2 f

i NRC DOCKl:T NO. 50-325, 50-324 FRC PROJECT CS606

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NRC TAC NO. 42876, 42877 FRC ASSIGNMENT 6 NRC CONTRACT NO. NRC43 41 110 FRC TASK 24."

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Preparedby Franklin Research Center Author:

A. K. Le, V. H. Con 20th and Race Street Philadelphia, PA 19103 FRC Group Leader:

V. N. Con i

Prepared for Nuclear Regulatoy Cornmission l

Washington, D.C. 2C,356 Lead NRC Engineer:

N. C. Chokshi November 16, 1984

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This report was prepared as an account of work sponsored by an agency of the United States Government. Netther the United States Government nor any a0ency thereof, or any of their employees, makes any warrantf, expressed or implied, or mesumes any l*0al llatHilty or responsibility for any third party's use, or the resulta of such use, of any information, appa-ratus, product or process disclosed in this report.. represents that its use by such third party would not infringe privetely owned rights.

Prepared by:

Reviewed by:

Approved by:

$h. h K %M hm fl Alper k ( Ter 5._CeA[*ps)

Principal Author:

Group Leader Department Director Late:

//- /d - 84 Date:

11 16 114 Date:

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i Section Title Page 1

INTRODUCTION 1

9 1

1.1 Purpose of Review.

1.2 Generic Issue Background 1

1 1.3 Plant-Spacific Background.

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2 EVALUATION CRI'!TRIA.

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TECHNICAL EVALUATION 4

3.1 Evaluation of Licensee's criteria.

4 3.2 Evaluation of Licensee's Approach to Wall Modifications 16 4

4 CNcCt,uSIONS.

17 5

REFERENCES.

18 a

APPENDIX A - SGES CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GE0 TECHNICAL ENGINEERING 3

l ERANCH (SGEB) OF THE NRC) 4 0

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FOREWORD l

This Technical Evaluation Report was prepared by Franklin Research Center 4

under a contract with the U,f. Iluclear Regulatory Commission (Of fice of i

Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NRC operating reactor licensing actions. The technical evaluation was conducted in accordance with criteria established by

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1.

INTRODUCTION i

i 1.1 PURPOSE OF REVIEW The purpose of this review is to provide technical evaluations of Licensee responses to IE Bulletin 60-11 (1)* with respect to compliance with the Nuclear Regulatory Commission (NRC) masonry wall criteria.

In addition, if a licensee has planned repair work on masonry walls, the planned methods and procedures are to be reviewed for acceptability.

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1.2 GENERIC ISSUE BACKGROUND i

In the course of conducting inspections at the Trojan Nuclear Plant,

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Portland General Electric Company determined that some concrete masonry walls i

did not have adequate structural strength.

Further investigation indicated l

that the problem resulted from errors in engineering judgment, a lack of established procedures and procedural details, and inadequate design i

criteria. Because of the implication of similar deficiencies at other i

o,nerating plants, the NRC issued IE Bulletin 80-11 on May 8, 1980.

IE Bulletin 80-11 required licensees to identify plant masonry walls and their intended functions. Licensees were also required to present reevaluation j

criteria for the assonry walls with the analyses to justify those criterie.

If modifications were proposed, licensees were to state the methods and schedules for the modifications.

j 1.3 PLANT-SPBCIFIC BACEGMOUND 1

In rtsponse to IE Bulletin 80-11, the Carolina Power and Light Company (CF6L) provided the NRC with documents (2, 3, 4, 51 describing the status of masonry walls at the Brunswick Steam Electric Plant Unita 1 and 2.

The information in these documents was reviewed, and a requent for additional information was sent to the Licensee (6) to which the bicensee responded [7].

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• Numbere in brackets indicate references, which are cited in Section 5.

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Additional questions [8] were sent to the Licensee, to which it has also responded [9].

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The Licensee identified 87 masonry walls as safety-related for both Units 1 and 2.

Fourteen are unreinforced walls and 18 are multiple-wythe walls.

The masonry walls at the Brunswick plant function as partitions, fire i

protection, or radiation shields. There is no safety-related piping attached to or supported from concrete masonry walls at the Brunswick plant. Light equipment, such as co.1 trol panels, junction boxes, and light fixtures, is attached to walls throughout the plant.

r..sonry wall types and natarials for the Brunswick plant are given belcw.

1 Wall Types:

7 safety-related walls 87 Walls requiring modifications 10 Walls being evaluated for possible 17 modifications wall Functions: partition, radiation shielding, fire protection construction Materials:

Mortar for Unit Masonry C270 Type M Masonry Units l

Hollow load-bearing partitions and walls C90 Grade N-1 i

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Solid units C145 Crade N-I l

Peinforcement ASTM 615-68 Grade 60 for I

sizes No. 6 to No. 11, and Grade 40 for smaller

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sizes.

Wire for seinforcement Standard Dur-O-Wal l

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EVALUATION CRITERIA 4

1 The basic documents used for guidance in this review were the criteria l

developed by the Structural Geotechnical Engineering tranch (SGER) of the NIC (attached as Appendia A to this report), the Uniform Building Code (10), and I

ACI 531-79 (11).

l In general, the materials, testing, analysis, design, construction, and insbetion of safety-related concrete masonry walls shout.d coninra to the SGER 1

criteria. For operatino plants, the loads and lo64 combinations for quali-1 fying the masonry walls should conform to the appropriate specifications in the Final Safety Analysis Report (FSAR) for the plant. Allowable stresses are specified in Reference 11 and the approptiate incJesse factors for abnormal i

and extreme environmental loads are given in the SGES criteria (Appa '

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TER-C5506-245 3.

TECHNX M EVALUATION This evaluation is based on the Licensee's earlier responses (2, 3, 4, 5) and subsequent responses (7, 9) to the requests for additional information (6, 8).

The Licensee's criteria (3) were evaluated with regard to design and analysis methods, loads and load combinations, allowable stresses, construction specifications, and materials. The Licensee's response to the request for additional information was also reviewed.

I 3.1 EVALUATION OF LICENSEE'S CRITERI A The Licensee reevaluated the masonry walls using the following criteria:

o Allowable stresses are consistent with ACI 531-79.

o Load combinations.are accoroing to the FSAR.

o The working stresk design method is used.

o The following damping values were used:

Unreinforced walls 24 - Operating basis earthquake (OBE) 46 - Safe shutdown earthquake (SSE)

Rcinforced Walls 44 - OBE 7% ~ GSE o The walls are modeled as beams or plates.

o The typical analytical proce4Jre is summarised below:

- determine wall boundary conditions

- calculate the wall's fundamental frequency

- calculate the seismic inertia load

- compare computed stresses with allowables.

Other than those areas identified in Section 4, the Licensee's criteria

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have been reviewed and foured to be technically adequate and in complianct with the SCEB criteria. The review of the Licensee's response to the request for additional information follows.. _ -.

1 TER-C5506-245 Question 1 Indicate whether the walls have stack bond or running bond.

If any stack bond wall exists, provide sample calculations to obtain moment and shear stress of a typical wall.

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Response 1 l

The Licensee confirmed that there are no stack bond walls at the Brunswick plants all walls have runr.ing bond construction.

The Licensee's response has resolved the concern on atack bond construc-tion at the Brunswick plant.

ouestion 2 Indicate how frequency variations due to uncertainties in mass, materials, and other parameters were considered.

Response 2 The Licensee indicated that the frequency variations due to uncertaintiss in mass, material, and other parameters were accounted for by varying the modulus of elasticity, En, between 1000 f'c and 600 f's for hollow masonry and between 1200 f's and 800 f's for solid or groutad masonry.

As a result of modulus of alssticity variation, -the wall's frequency will vary accordingly and the peak acceleration from the analified response spectra can be selected.

The Licensee's response is adequate and in compliance with the SGEB criteria.

Question 3 Describe how in-plane interstory drift was considered.

Response 3 The Licenste indicated that the in-plane interstory drif t was considered by comparing the in-plane strain induced in the wall to the in-plane strain

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limits. For unconfined valls, this limit is 0.0001, and for confined walls bounded on top and bottom or bounded on three sides, the following formula was t

appliedt 1 + [B/H)2 2000 B/H where D = wall width and H = height.

4 For confined walls at this plant, the smallest value for B/R is 0.667, wnich results in a = 0.001 and a will be smaller if B/H becomes larger. The value of a = 0.001 has been judged to be acceptable in other plants. The j

Licensee stated that all masonry walls at the Brunswick plant respond within the above limit. As has been observed in other plants, the above formula was proposed based on a number of availabic test data and it is judged to be adequate and satisfactory.

Request 4 Indicate if cracking of sections was given proper consideration in the analysis.

Response 4 f

The Licensee indicated that cracking is not permitted in unreinforced masonry walls. For reinforced masonry walls, cracking was properly accounted a

for in both frequency and strength calculations. Frequency variations which 4

account for cracking were considered by calculating the effective moment cf inertia of a cracked masonry wall. Cracking was accounted for in strength calculations by assuming the masonry takes no tension (for reinforced masonry).

The Licensee's response is satisf actory and in compliance with the SGEB criteria.

gue,stion 5 Indicate whether the bic k pullout was cor:sidered in the evaluation. If yes, provide sample calculations of block pullout analysis.

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Response S, 2

ane Licensee stated that block pullout was considered in the evaluation of mesonry walls. The sample calculation was provided for an 8-in single-wythe wall.

The pullout strength was found to be 6200 lb for unreinforced block and

$1,000 lb for reinforced block. There were no attaches.it supports to individual blocks with loading in excess of the pullout strength.

The Licensee stated that field surveys of the various attachments to the masonry walls at the Brunswick plant were reviewed. The Licensee concluded that there were no attachment supports to individual blocks with loading in I

excess of the pullout strength.

The Licensee's response is adequate and in compliance with the SGEB criteria.

Question 6 In Reference 3, the Licensee indicated that loads and load a.

combinations are based on the NRC Standard Review Plan for the l

elastic design method. The Licensee is requected tc clarify whether they are consistent with the Plant Final Safety Analysis Repott l

(FSAR).

If any deviations exist, justification should be given.

b.

With reference to load combinations, the Licensee is requested to provide justification for the stress factors of 1.5 for dead plus live plus abnormal temperature loads and 1.1 for dead plus live plus DEE seismic plus abnormal temperature loads.

c.

In Reference 3, the Licensee indicated that impulsive and impactive loads were considered. Describe types of these loads (pipe rupture, l-missile impact, etc.).

Also, provide a sample calculation l

illustrating how these loads were treated in the analysis.

i Response 6 With regard to loads and load combinations, the Licensee confirmed l

a.

l that the load combinations are consistent with those in the Plant Final Safety Analysis Report (FSAR).

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b.

With regard to the stress factors, the Licensee indicated that the increases were included in the criteria because thermal loads are secondary and self-relieving in nature. Stress increases are normally taken in design for load equations involving temperature.

The masonry walls evaluated in this program were not subjected to postulated temperature gradients through the thickness. Therefore, l

the wall would not experience hermal-induced flexural or shear

stresses, c.

With regard to walls subjected to iepect loads, the Licensee indicated that the impact loads are applicable to masonry walls which separate the diesel generators in the diesel generator building.

These walls are reinforced. Each side of the masonry walls is l

protected by a 1/4-in steel plate attached by through bolting with 3/4-in diameter bolts. The following are commitment;s related to potential missiles generated by the air receivers that exist in each of the diesel generator rooms bntween the steel plate protected masonry walls.

Case 1 - A 2-in diameter plug of weight 1.38 lb which becomes loose j

and is propelled by exhausting air.

i Case 2 - The air receiver is punctured and becomes a jet propelled missile.

Case 3 - The air receiver explodes into fragments. A fragment is idealised as a :t-in-diameter circular disc.

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The sample cal-ualtion for case 1 was illustrated. The Licensee stated that this was the most severe wissile impact case Nnd enveloped that associated with case 3.

For case 2, a puncture in the tout severe location was postulated and the Licensee stated that attachC.i and supports of the air receivers were adequate to prevekt impact on the masonry walls. Therefore, no is. pact calculations were performed for case 2.

The sample calculation indicated that a penetration thickness of 0.12 in is le i than the thickness provided by the steel plate which is 0.25 in. 'thu l

overall stability of the wall, which is subject to the same postulated missile as care 1, war. checked by comparing'.ae calculated ductility ratio with the allowable ductility ratio. The calculated ductility ratio of the wall was l

found to be 3.7, which is smaller than the alleveble ratio of 10.

The Licensee's rarponse is judged to be adequate.

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Question,J Show, by sample calculation, how the ef f ect of highet modes of vibration was considered in the analysis.

Respor.se 7 The Licensee referred to a study contained in the " Recommended Guideline for the Reassessment of Safety Related Masunty Oslls," dat2d October 6, 1980 4

and prepared by Owners and Engineering Firms Informal Group on Concrete Masonry Walls. and stated that this study demonstrates that the first mode contributes to over 99% of the total flexural response. The Licensee also stated that similar results are expected for shear at the boundary: therefore, higher modes were not accounted for in the calculation of stresses. Moreover, the peak accelerations were assumed to exist uniformly over the entire wall.

The Licensee's resonse is edequate and in compliance with the SGFD eriteria.

Question 8 Indicate whether the construction practice for the masonry walls at the Brunswick plant was in confermance with the provisions specified for the special anspection category in ACI 521-79 [8).

If not, explain and justify the use of allowable stresses.

i Responso 8 With regard to the construcklon practice, the Liiensee indicated that a daily inspection by the superintendents for the subcontractor, contractor, and ewner was perfoceed during the construction of the masonry walls.

The allowable stresses us'd in the design of the masonry walls at the e

Brunswick plant were those normally for masonry work at the time the plant was ccastructed.

I In addition, some tests were conducted to verify the allowable strength of the walls being analyzed. See Response 9.1 for more details.of the 3

laboratory test results to verify the assumed values or masonry and mortar strength used in the analysis.,

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Question 9 I

with respect to Tables A-2 and A "J

[3), justify the use of the following increase for factored loads (the increase factors allowed in the SGEB criteria (6) are shown in parentheses):

shear in flexural members 1.5 (1.3) 1 tension normal to the bed joint 1.67 (1.3) tension parallel to the bed joint 1.67 (1.3)

If the Licee.see intends to use any existing test data to justify these f actors, the Licensee is requested to discuss the applicability of these tests to the masonry walls at the plant to the following areas:

o nature of loads o boundary conditions o materials used o size of test walls.

Response 9 The Licensee indicated that the increase f a.' ors for both flexural members and shear walls have been established based on tests for shear walls.

The Licensee referred to two test programs:

the first one was performed by Schneider, and the second was performed at the University of California, Serkeley. The Licensee ' stated,: st these test results were used as a comparison with the code allowables. See further details relative to this subject in Peoponse 9.3.

Ouestion 10 In Reference 3, the Licensee-indicated that the energy balar.ce technique and arching theory have been used to qualify some masonry walls. The NRC, at present, does not accept the application of these techniques to masonry walls in nuclear power plants in the absence of conclusive evidence to justify this application. The Licensee is requested to indicate the number of walls which have been analyzed by each of these techniques and to provide the resulting stresses and displacements.

The following areas need technical verification before any conclusion can be made about thes2 techniques:

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J TER-C5506-245 1.

Energy Balance Technique i

f o For the walls which were analysed by uring the energy balance technique, provide the technica3 t'esis to ensure that the ductile mode of f ailure will take place (if they f ail).

o Provide justification and test data (if avg lable) to validate the applicability of the energy balance technique to th6 masonry structures at Brunswick Units 1 and 2 with particular emphaiis on 4

the following areas:

i a.

nature of the load b.

boundary conditions c.

material strength d.

size of test walls.

2.

Arching Theory o Explain how the arching theory handles cyclic load!ng, especially when the load is reversed.

o Provide justification and test data (if available) to validate the applicability of the arching theory to the masonry structuret; at Brunswick Units 1 and 2 with particular emphasis on the following areas:

i a.

nature of the load j

b.

boundary conditions c.

materisi strength d.

size of test walls.

_o If hinges are formed in the walls, the capability of the structures to resist in-plane shear force would be diminished, and l

shear failure might take place. This in-plane she.r force weJid j

also reduce the out-of-plane stiffness. Explain how the effect of this phenomenon can,be accurately determined.

Response 10 l

l See Response 9.5.

Question 11 Regulatory Guide 1.61 allows 4% damping for an OBE and 7% damping for a SSE.

Provide justification for using 10% damping for-unreinforced walls in the arching action analysis, i

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B Response 11 i

See Response 9.5.

Question 12 l

l With reference to the multiple wythes. clarify whether the co?,lar joint strength was used in the analysis.

If so, justify the allowable stresses of the collar joint. Also, provide sample calculations illustrating the analysis of multiple-wythe walls.

Response _12 The Licensee stated that the composite action was not used in the analysis of multi-wythe walls and each wythe was assumed to act independently. Therefore, the allowable stresses in the collar joint are not applicable.

The Licensee provided sample calculations for the analysis of i

multiple-wythe walls os follows:

For Unit 1, the wall is 8 f t 8 in long,16 f t 4 in high, and 2 f t 0 in tnick (3 wythes at 8 in).

For Unit 2, the wall is 8 f t 8 in long,16 f t 4 in high, and 2 f t 0 in thick (2 wythen at 12 in).

Both of these walls are at elevation 17 ft 4 in the reactor building.

For the wall considered as a single 8-in wythe with seismic acceleration l

i of 0.28 g for OBE and 0.435 g for SS3, the calculated flexural stress and shear stresses were found to be.)7 pai, and 1.3 pai, which are smaller than the allowable stresses of 75 psi and 47 pai for OBE.

The calculated flexural and shear. stresses for SSE were found to be 43 psi and 2 psi, which are i

l smaller than the flexural and shear allowable stresses of 125 psi and 72 psi, respectively.

I For the walls considered as a single 12-in wythe in Unit 2, with seismic accelerations of 0.127 g for OBE and 0.47 g for SSE, the calculated flexural j

and shear stresses wert found to be 16 psi and 1.2 pai, which are smaller than the allowable stresses of 75 poi and 47 psi for OBE.

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and shear stresses for SSE were found to be 28 psi and 2 psi, which are smaller the flexural and ghear allowable streser of 125 psi and 72 psi, I

respectively.

The Licensee's responsa is adequate and in compliance with twEB criteria.

Question 13 Provide detailed drawings and current status of proposed repairs. Also, provide a sample calculation to illustrate that the modified walls will 4

be qualified under the working stress design condition, 2

i Responce 13 With regard to the status of proposed repairs, the Licensee stated that some repairs have been implemented in 1983.

The remaining repairs will be completed in 1984.

The Licensee provided a sample calculation for wall da at elevation 5 ft 4

4 0 in in the diesel generator building. The wall is reinforced filled wall, 8-in thick. Structural steel member WB x 31 was attached to one side of the wall at 25 f t 6 in maximum spacing with two 3/4-in throughbolts at 16-in spacing. Also, restratnt angles were 1:atalled on top of walls. These

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modifications make the wall behave as a plate.

A review of the sample calculation indicated that the calculated stresses are within the SGER code allowable. Therefore, the Licensee's response is considered adequate and in compliance with the SGER criteria.

i Question 9.1 With reference to the reinforcement in masonry walls, the ACI 531-79 Code

[1] specifies that the minimum area of reinforcement in a wall in either direction, vertical or horizontal, shall be 0.0007 (0.07%) times the gross cross-sectional area of the wall and that the minimum total area of steel, vertical and horziontal, shall not be less than 0.002 (0.2%) times the gross crona-sectional area. In view of this, clarify whether the reinforced walls at this plant meet the above requirements..It should be noted that the horizontal reinforcement is installed to satisfy the minimum reinforcement requirement for a reinforced wall.

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If joint reinforcement is used to resist tension, it should follow the working stress design method, which limits its allowable to 30 ksi. The Licensee is requested to clarify if this requirement has been satisfied.

If this requirement is not satisfied, idwntify all affected walls along with the calculated stress value for each wall.

Indicate if there is any wall that has only joint reinforcement (horisontal reinforcement), no vertical reinforcement, and may have been i

qualified using the tenstle resistance of the joint reinforcement. It should be noted that the NRC, at prt sent, does not approve the use of joint reinforcement to qualify this type of wall.

Indicate all walls belonging to this category.

j Response 9.1 With regard to the minimum area of reinforcement, the Licensee confirmed that the reinforced walls at the Brunswick plant meet the requirennents of ACI 531-79 with regard to the minimum area rif reinforcement.

i The Licensee also clarified that horizontal joint reinforcing was not i

used to resist tension in evaluating masonry wallas therefore, no walls were qualifind using the tensile resistance of the joint reinforcing.

The Licensee's response is satisf actory and in compliance with the SGES criteria.

Question 9.2 i

Regarding Response f of Reference 2, please provide laboratory test results to verify the assumed values of masonry and mortar strength used in the analysis.

Response 9;22 l

With regard to the test results of masonry blocks, the Licensee referred j

to testa performed by Pittsburgh Testing Laboratory for the two-core hollow load bearing block and the 100% solid block. The test results for the ecore hollow load-bearing block indicated an average strength of 1520 psi compared with the ASTM C90-70 compressive strength of 1000 pai.

The Licensee stated that no tests were performed on the mortars however, the plant's Specification (9527-01-29-1) required that the mortar adhere to a.

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Type of Stress Factor Axial or Flemural Compression 2.5 Bearing 2.5 Reinforcement stress except shear 2.0 but not to exceed 0.9 fy Shear reinforcement and/or bolts 1.5 4

Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 l

Masonry tension perpendicular to bed joint for reinforced masonry 0

2 1,3 for unreinforced mascnry Notes (1) when anchor bolts are used, design thould prevent facial spalling of masonry unit.

(2) see 3(c).

4.

Design and Analysis Considerations (a) The analysis should follow established principles of engineering 4

mechanics and take into account sound engineering practices.

(b) Assumptions and modeling techniques usod shall give proper considerations to boundary conditions, cracking of sections, if any, and the dynamic behevsor of masonry walls.

(c) Damping values to be used for dynamic analysis shall be those for reinforced concrete given in Regulatory Guide 1.61.

(d)

In general, for operating plants, the seismic analysis and Category I structural requirements of FSAR shall apply. For other plants, corresponding SRP requirements shall apply. The seismic analysis shall account for the variations and uncertainties in mass, materials, and other pertinent parameters used.

(e)

The analysis should consider both in-plane and out-of-plane loads.

(f)

Interstory driit effects should be considered.

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the following ASTM Standards: ASTM C91, ASTM C144, ASTM C270, ASTM C476, and i

ASTM C780.

i The Licensee's response is considered adequate.

Question 9,3 with respect to the increase factors for load combinations containing SSE or accident load case (2), please identify all wa;1s that would not be

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qualified if the SGEB criteria (3) were to be used. The Licensee is advised to explain all conservative measures (if any) used in the analysis to justify a higher increase factor.

i Response 9.3

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The Licensee stated that all walls qualify when the SGER criteria is used, except walls 8a and 8b in the reactor building, which are unreinforced 4-f t-thick multiple-wythe walls. Walls Sa'and 8b would not be qualified if the SGER criteria were to be used on a single 8-15 vyther however, they do 1

qualify when evaluated as a single 4-ft section. It is noted that the strength of the collar joint was specified as 8 psi (shear and tension) for the CBE case and 12 psi for the SSE case. Based on tests results performed at the Trojan nuclear plant, the values are judged to be conservative.

The Licensee's response satisfies the SCEB criteria.

Question 9.4 with regard to wall modifiE4tions, the Licensee indicated that some fixes have been designed to be implemented in 1983 and that the design for the remaining fixes will be completed in 1984 and detailed drawings are not available (2). Please provide the following informations a.

Total number of walls to be fixed b.

General description of the types of fixing c.

Schedule for completion of wall repairs d.

Detailed drawings.

Response 9.4 The Licensee indicated that 10 walls which were qualified by the arching action theory and energy balance technique will be modified to meet SGEE code.

,1-.-.

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l TER-C5506-245 i

requirements. In addition, the Licensee is currently evaluating 17 additional walls for which a determination as to the necessity of a fix has not yet been made. The implementation of any necessart repairs for any additional walls resulting from evaluation of the 17 Walls will be scheduled when and if such repairs are ascertained to be required. The types of modifications to be implemented include the addition of steel plasters, a steel grading restraining wall, and steel bugles installed at the boundary.

Because the Licensee has made a commitment to modify walls so that they I

are in compliance with the SGEB criteria, this change should be acceptable.

I ouestion 9.5 with regard to the nonlinear analysis technique (energy balance technique and arching action theory), please note the following information:

a.

Arching Actions The NRC position on this issue states that the use of the-archin'; action theory to qualify unreinforced masonry walls is not acceptables these walls should be repaired so that they can be qualified based on the SG13 criteria [3].

(The NRC position is attached.)

l b.

Energy Balance Techniques The NRC is currently preparing a position statement regarding this technique, which will be forwarded to the Licensee in the near future.

l Response 9.5 See Response 9.4.

3.2 EVALUATICM OF LICENSEE'S APPROACH TO WALL MODIFICATIONS i

As indicated in Section 3.1, the modifications include the addition of steel pilasters, a steel grading restraining wall, and steel. angles installed at the boundary. The sample calculation of a modified wall has been reviewed and proved that it satisfies the SGES criteria.

i.

e i

TER-Cf 506-24 5 4.

CONCLUSIONS 1

I A detailed study was performed to provide a technical evaluation of the 4

masonry walls at the Brunswick Steam Electric Plant Units 1 and 2.

Review of the Licensee's criteria and additional information provided by the Licensee led to the conclusions given below.

The criteria used for reevaluation of the masonry walls, along with the additional information provided by the Licensee, indicate that the Licensee's i

criteria are in compliance with the SGER criteria.

Section 3.2 indicated that 10 walls have been modified, and 17 walls are still being reevaluated. Any additional modifications which determined to be necessary will be implemented. The Licensee's approach to wall modification is judged to be satisfactory, and the modified walls were verified through sample calculations to be structurally adequate and in compliance with the SGEB criteria.

J I

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1 TER-C5506-245 5.

REFERENCES 1.

IE Bulletin 80-11 Msaonry Hall Design NBC, 08-May-8D 2.

B. J. Furr Letter to J. P. O'Reilly, NRC.

Subject:

Brunswick Steam Electric Plant, Unit Nos.1 and 2 - Response to IE Bulletin 80-11 (Attached)

Carolina Power & Light Co., July 7, k980 NO.-80-1009 3.

B. J. Furt Letter to J. P. O'Reilly, NRC.

Subject:

Brunswick Steam Electric Plan *., Unit Nos.1 and 2 - Response to IE Bulletin 80-11 (180-Day Response) ( Attached) -

Carolina Power & Light Co., November 5, 1980 NO-80-1632 4.

B. J. Furr Letter to J. P. O'Reilly, NRC.

Subjects - Brunswick Steam Electric Plant, Unit Nos. 1 and 2 - Supplemental Response to IE Bulletin 80-11 Carolina Power & Light Co., November 25, 1980 NO-80-1746 5.-

B. J. Furr Letter to J. P. O'Reilly, NRC.

Subject Brs.

Steam Electric

IE Bulletin 80-11 Plant, Unit Nos.1 and 2 - Supplemental Respo Carolina Power & Light Co., December 9,1980 NO-80-1739 6

D. B. Vassa11ti, NRC Letter to F. R. Eisumerman, CP&L

Subject:

Brunswick Steam Electric Plant, Unit Mos.- 1 mM IE

-B dletin 80-11, Masonry Derign - Request for Additional Information August 2, 1982 7.

5.1s Sisumerman, CP&L -

Letter to D. B. Vassallo,. NRC

Subject:

Brunswick Steam Electrih Plant, Unit Nos. 1-and 2 - IE Bulletin 80-11, Mtsonry Design - Response to Request for Additional Information July 29, 1983 8.

D. B. vassallo, NBC F

Letter to S. R. Einmerman, CP&L Subjects Brunswick Steam Electric Plant, Unit Nos.1 and 2 - IE Bulletin 30-11, Masonry Design - Request for Additional Information

-February 21, 1984 - -

.. _ ~

-~. - -...

TER-C5506-245 9.

A. B. Cutter, CP&L Letter to D. B. Vassallo, NBC Subj ect: Brunswick Steam Electric Plant, Unit Nos. 1 and 2 - IE Bulletin 80-11, Masonry Design - Request for Additional Information April 27, 1984 1

10.

Uniform Building Code International Conference of Building of ficials,197S 11.

Building Code Requirements for Concrete Masonry Structures Detroit American Concrete Institute, 1979 ACI 531-79 and ACI 531-R-79 J

12.

NCMA - Specification for the posign a >/ "

struction of Load Bearing Concrete 4

1 1

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APPENDIX A i

SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GEOTECHNICAL ENGINEERING BRANCH (SGEB) OF THE NRC) e 6

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i FRANKUN RESEARCH CENTER DM90N OF ARVIN/CALSPAN 20th and P. ace Sweets. Phila., Pa. 19103 (215) 448-1000 i

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TER-C5506-245 CONTENTS

' Title Page S,ection A-1 1

GENERAL REQUIRLElNTS A-1 2

LOADS AND LOAD COMBINATIONS.

A-1 a.

Service Load Combinations b.

Extrere Environmental, Abnormal, Abnormal / Severe Envitcamental, and Abnormal / Extreme Environ 7 ental A-2 Conditions.

A-2 3

ALLOMABLE STRESSES.

4 DESIGN AND ANALYSIS CONSIDERATIONS.

A-3 A-4 5

REFERENCES.

O 4

f 4

4 111

TER-C5506-245 i

1 1.

General Requirements The materials, testing, analysis, design, construction, and inspection related to the design and construction of safety-related concrete masonry walls should conform to the applicable requirements contained in Uniform Building Code - 1979, unless specified otherwise, by the provisions in i

this criteria.

The use of other standards or codes, such as ACI-531, ATC-3, or NCMA, is also acceptable. However, when the provisions of the.e codes are less conservative than the correspoeding provisions of the criteria, their use should be justified on a case-by-case basis.

In new construction, no unreinforced masonry walls will be permitted. For operating plants, existing unreinforced walls will be evaluated by the provisions of thase criteria. Plants *'hich are applying for an operating 4

license and which have already built unreinforced masonry walls will be evaluated on a cart-by-case basia.

2.

Loads and Load Combinations The loads and load combinations shall include consideration of normal loads, severe environmental loads, extreme environmental loads, and abnormal loads.

Specifies 11y, for operating plants, the load combinations provided in the ' plant's FSAR thall govern. For operating license applications, the following load combinations shall apply (for definition of load terms, see SRP Section 3.8.4II-3).

(a)

Service Load Conditions (1) D+L (2) D+L+E (3) D+L+W If thermal stresses du to T and Ro are presant, they should be o

included in the above combinations as follows:

(la) D + L + To + Ro (2a) D + L + To + Ro + E (3a) D + L + To+Ro+W Check load combination for controlling condition for maximum

'L' and for no

'L'.

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i TER-C5506~245 (b)

Extreme Environmental, Abnormal, Abnormal / Severe Environmental, and

{

Abnormal / Extreme Engtonnental Conditions l

(4) D + L + To + Ro + E i

(5) D + L + To + Ro + Wg i

i (6) D+L+Ta+Ra + 1.5 Pa j

(7) D+L+Ta + Ra + 1.25 Pa + 1. 0 (Y r + Y j + Y,) + 1.25 E (8) D + L + Ta + Ra + 1.0 Pa + 1.0 (Yr + Yj + Ym) + 1.0 E' 4

In combinations (6), (7), and (C) ths maximum values of P.,

T '

a Ra, Y, Yr, and Y, including an appropriate dynamic load 3

f actor, should be used unlee4 a time-history analysis is performed to justify otherwise. Combinations (5), (7), - and (8) ar.J the i

corresponding structural acceptance criteria should be actisfied first without the tornado missile load in (5) and without Y ' Ij' r

and Ya in- (7) and (8). When considereing these. loads, local i

section strength captcities may be exceeded under these concentrated loads, provided tnere will be no loss of function of any i

safety-related system.

Both cases of L having its full value or being completely absent should be checked.

j 3.

Allowable Stresses l

Allowable stresses provided in ACI-531-79, as supplemented by the i

following modifications / exceptions, shall-apply.

(a) When wind or seismic loads (ObE) are considered in the loading combinations, no increase in the allowable stresses is permitted.

(b) Use of allowable stresses corresponding to special inspection estegory shall be substantiated by demonstration of compliance with the inspection requirements of the SEB criteria.

(c) When tension perpendicular to bed joints is ueM in qualifying the unreinforcoJ masonry walls, the allowable value will be justified-by tese program or other means pertinent to the plant and loading 4

conditions. For reinforced masonry walls, all the tensile i'resses will be' resisted by reinforcement.-

J-(d). For load conditions which represent extreme environmental, abnormal, abnormal / severe environmental,-and abnormal / extreme environmental-conditions, the allowable working stress may be multiplied by the factors shown in the following tables i

l A-2

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i TER-C5506-246 i

Type of Stress Factor Axial or Flexural Compression 2.5 Bearing 2.5 a

Reinforcement stress except shear 2.0 but not to exceed 0.9 fy Shear reinforcement and/or bolts 1.5 i

Kasonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular i

to bed joint for reinforced masonry C

2 1,3 i

for unreinforced masonry Notes (1)

Fhen anchor bolts are used, design should prevent f acial i

wealling of masonry unit.

(2)

See 1(c).

4.

Design and Analysis Considerations (a) The analysis should follow established principles of engineering mechanics and take into account sound engineering practices.

(b) Assumptions and modeling techniques used shall give proper considerations to boundary conditions, cracking of sections, if any, and the dynamic behavior of masonry walls.

(c) Damping values to be used for dynamic analysis shall be those for reinforced concrete given in Regulatory Guide 1.61.

(d) In general, for operating plants, the seismic analysis and Category I i

structural requirements of PSAR shall apply. For other plants, corresponding SRP requirements shall apply. The seismic analysis shall account for the variations and uncertainties in mass, materials, and other pertinent parameters used.

(e)

The analysis should consider both in-plane and out-of-plane loads.

(f) Interstory drift effects should be considered.

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TER-C5506-24 5 a

1 (g)

In new construction, grout in concrete masonry walls, whenever used, shall be compacted by vibration.

(h) For masonry shear walls, the minimum reinforcement requirements of ACI-531 shall apply.

(i)

Special constructions (e.g., multiwythe, composite) or other items not covered by the code shall be reviewed on a case-by-case basis for their ac;eptance.

j (j)

Licensees or applicants shall submit QA/QC information, if availacle, for staff's review.

2 In the event QA/QC information is not available, a field survey and a test program reviewed and approved by the staff shall be implemented to ascertain the conformance of masonry construction to design drawings and specifications (e.g., rebar and grouting).

l (k)

For masonry walls requiring protection from spalling and scabbing due to accident pipe reaction (Yr), jet impingement (Y ), and missile 3

impact (Yn), the requirements sicilar to those of SRP 3.5.3 shall apply. Euwever, actual review will be conducted on a case-by-case basis.

5.

References (a)

Uniform Building Code - 1979 Edition.

(b)

Building Code Requirements for Concrete Masonry Structures ACI-531-79 and Commentary ACI-531R-79.

(c)

Tentative Provisions for the Development of Seismic Regulations for i

Buildings - Applied Technology Council ATC 3-06.-

(d)

Specification for the Design and Construction cf Load-Bearing l

Concrete hasonry - NCMAr, August,1979.

i

}

(e)

Trojan _. Nuclear Plant Concrete Masonry Design Criteria Safety Evaluation Report Supplement - November, 1980.

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ATTACHMENT 6 9

1 QUESTION 10 RESPONSE Sketch of Self Drilling Anchors 4

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• Drills its own hole, eliminatmg costly carbide bits.

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• Installs fast alth both the 700 and the 747 Roto Stop TQ hammers.

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• Economical solution to heavy-duty anchoring requirements.

Self-Drilling Anchors provide their own case-hardened steel drill PHI L LIPS 1

for every hole. Installation with RED HE AD Roto Stop Hammers creates Red Head' one on the fastest, simplest and most economical anchoring systems in the wor:d.. especially for overhead applications.

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ATTACHMENT 7 l

QUESTION 10 RESPONSE Tables 3 and 4 from BSEP/SP 79 22

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ACCEPTABLE PLUG DEPTH, SELF-DRILLING ANCHORS i

Anchor Size Plug Depth

• 3/8" 25/32" 1/2"

.1 5/32" 5/8" 1 13/32" i

l 3/4" 1 31/32" 7/8"

2. 9/32" i

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• Plug Depth = (Anchor Length) - (Plug Length) (+ 1/8")

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TABLE 4 4

MINIMUM THREAD ENGAGEMENT, SELF-DRILLING ANCHORS

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5 ATTACHMENT 8 1

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Caroi;na Power L Light Company Brunswick Stear.. Elcetric Plant P. O. Bo:: 10429 Southport, NC 28461-0429 4

l July 26, 1982 FILE:

BJ9-13510C SERIAL:

BSEP/82-1616 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Rcgion II, Suite 3100 101 Marietta Street N.V.

Atlanta, GA 30' - )

BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO, 50-324 LICENSE NO. JPR-62 SUPPLEMENTAL RESPONSE TO IE BULLETINS 79-02, 79-07, AND 79-14 5

Dear Mr. O'Reilly:

In our letter (BSEP/81-0440) dated February 25, 1981, we committed to complete the Phase I and Phase II portion of the scismic reanalysis of the plant to satisfy the requirements of IE Bulletins 79-02, 79-07 and 79-14 by July 31, 1981, and March 31, 1982, respective.ly. This letter is to report the Phase I, or generic analysis, and Phase II, the individual analysis, have been completed in accordance with these dates.

The Phase I and Phase II programs did not include as-built evaluation of inaccessibic isometrics as that work required a unit outage for access to complete. Thest isometrics on Unit No. 2 have been as-built and reanalyzed during the current outcge. Two inaccessible isotactrics in Unit No. 1 remain.

These will be as-built and evaluated during this year's outage.

In the February 25, 1981, let'er, we provided a list of potential problem areas and inconsistencies that were discovered during our revicw program, together with intended resolutien and schedules. We will address the status of these areas in the same order as listed previously.

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A, Lines Originally Seismically Analyzed,. But Not Included in IE Bulletin 79-07 Efforts 3

Upon the completion of the seismic line review, 38 isometrics remained to be analyzed.

Twent)-one of tt:ese isometrics were addressed under the February 25, 1981 letter. The remaining 17 (isometrics) were analyzed 4

under the Phase I program.

There were no short-term fixes required based on this analysis.

All long-term fixes associated with these isomotrics.

i have been issued and are in the process of being installed. We plan to l

complete the fixes associated with these isometrics on both units.by the j

end of the next Unit No. 1 refueling outage.

This outage is presently j

scheduled to start in September 1982.

For Unit No. 2, approximately 35 inaccessibic (during power operation) fixes nay not be completed during the current outage, however, due to insufficient outage time.

If necessary, these few remaining supports will be completed during the.next available outage of sufficient duration, and no later than the end of the 5

next Unit No. 2 refueling cutage.

B.

Vents, Drains, Instrument Connections i

These connections were not. covered by the original computer analysis so i

they did not fall under the scope of IE Bulletins 79-07 and ' 1-14.

It j

was determined they should be evaluated to give reasonable assurance that they did not significantly affect-the process piping.

A generic analysis f

of these connections showed a negligible effect for large bore piping.

The remaining small bore piping was handled by a sampling program.

5 Appronimatelyhalfoftheseconnectionswereanalyzedwithnocasesof

?

overstress on the process pipe.

It was thus concluded that no significant impact on the analysis of the parent lines existed.

l C.

Unanalyzed Loads Due to Valve Eccentricit,y In our letter of February 25, 1982, approximately 25 motor-operated j

valves were cited as not having been-analyzed for eccentric loadinas.

All but four have been evaluated based on UELC estimated valve and 1

operator weights and centers of gravity.

Efiorts to verify the assumed values with vendors have indicated that the estimated' values are as accurate'(

10 percant) as any vabi's which could be supplied by the manufacturers..Si u e the: analyses will not be significantly_affected by a 10 percent varian t e in weights and-the vendor's-estimates will not improve the accuracy of the analysis, the vendor verification program was i

terminated. The remaining four' valves were not originally computer j

analyzed and, therefore, are not encompassed by IE Eulletin 79-07.

liowever, a generic analysis was performed on these lines which verified-that the piping stresses are within ANSI B31.1 limits.

(-

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i Mr. O'Reilly July 26, 1982 4

D.

Verification of Acceptable Containment Pene,tration Nozzle Loads All penetration nozzle loads have been verified as acceptable per the i

requirements of IE Bulletins 79-07 and 79-14.

j E.

Vendor Supplied and Vendor - A/E Interface Piping After a review cf vendor documentation, we have concluded that these d

l lines woro not computer analyzed.

IE Bulletins 79-07 and 79-14 thus do not apply.

4 F.

Small Nozzle Loads on Safety-Related components i

The only lines encompassed in this-category are the vent and drain lines l

off the HPCI, RCIC and core spray psmps, which were analyzed.

I The IE Bulletin 79-14 condition has been reviewed and no short-term fixes were required.

Long-term fixes are scheduled on the same basis discuss 1 I

for Item A.

G.

Sofsmic Requirements Inconsistancies 1

j Only two lines under this category were found to require analysis; one is l

the surge line in the Diesel Fresh Water Cooling System, the other is a drain line in the Standby Liquid Control System. These lines are small and were not originally computer analyzed. Therefore, the 79-07 Bulletin is not applicable.

However, in order tn completely clot.9 out.

]

all outstanding items, these lines were as-built and evaluated as cart of Item A.

1 H.

CRD Syst<m Basenlata Flexure Analysis In regard to our bulletin-requirements for th: CRD System supports, we a

stated in our February 25, 1981 letter, " Completion oi baseplate flexure-j analysis on CRD-piping not ossintial to safe shutdown-is schedu'ed for 2

completion'as part of the Phase II Program." CP&L has determined that nonessential portions of the CRD System are not safety related or seismically qualified; therefore, this analysis'was not required, j

I.

Anchor Bolt Testing As stated in our-February 25,198111etter, the scheduled anchor bolt 4

l testing per.IEB-79-02 of all the additional supports.identiff.ed for testing is now complete-for Unit No. 2.

i s

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r Mr. O'Reilly July 26, 1982 4

j.

The testing of self-drilling anchors included application of a torque representing a pull out load equal ta or greater than the allowable design lecd for the anchor.

Concrete embedmont and thread engagement j

were also measured whenever it was possible to remove the bolt / stud from the anchor.

It cust bn noted here that this phase of test program covered many floor mounted suppo:'., cmploying scif-drilling anchors with-1 all thread rod studs and grout.

Mt:ause of moisture conditions during plant operation several studs were found to be frozen in anchors a,nd l

could not be removed for measurement of depth.

All of these anchors, j

howiver, either passed the preload test,or were replaced.

i All supports that did not meet the test acceptance criteria.were conservatively evaluated for the load values generated by IE 79-07 i

reanalysis effort.

Repairs were made to deficient supports and the.

frozen studs broken during test.

Rusted self-drilling anchors in service water intake structure were replaced by stainles; steel wedge i

anchors.

t A totcl of :63 baseplates containing 433 anchors were included under-this phase of the program.

All baseplates and anchor batte were tested to the extent as was reasonably possible.

The primart st verifying i

adequate preload was performed on 88 percent of all an, wr' bolts and_nn least one anchor bolt on all of the baseplates except two.

One of-at these baseplates had a seismic load of one pound-and the other.a safety j

factor of 20.

These loads are sufficiently' low that the satisfactory

]

inspections of their condition when testing was_ attempted was adequate to l

assure their reliability.

The preload test demonstrated t.he actual l

ability of each anchor bolt to withstand its design load,- The failure j

rate for this test was 2.4 percent. The inability to-back off the i

leveling nut was the predominent reason for-net testing all of the-anchors.

A stuck leveling nut does not indicate any structural' 1

deficiency with an anchor, it just provented any meaningful testing.

l The low failure rate and the extensiveness of'the test program for both i

baseplates and anchors provides a high confidence-in.the ability of.the l

existing anchor _ bolts to accommodate the required loads.

l Tests 'for proper installation were performed on 59 percent.of the anchor-bolts.

A failure rate of'l.6 percent was obtained for improper i

engagement and 1.6 percent for inadequate.cmbedment.._ Problems with anchor bolts or studs which could not be removed (27 percent of all anchors), in addition to the previously mentioned frozen 1cveling_ nut

[

problems (9 percent of all anchors), were the overriding reasons i

preventing full testing.

All of the anchors with unremovable bolts or-

}

studs were successfully tested-for proload, however,. demonstrating the load capability of the anchors.

This satisfactory demonstration and the I

low failure rates indicate there is no concern-for inadequate embedment and engagement.

In addition, 31 percent'of these anchor bolts which_were r.r t fully _ tested were subsequently replaced for other reasons further reducing the number of not fully verified anchors.

i 4.

i

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-... - _.. _ -. - ~ - - -

h i-Hr. O'Reilly

'5-July 26, 1982 j

An overall failure rate of 5.6 percent was obtained from the testing

{

program on Unit No. 2.

Thu extensiveness of the preload testing, the low j

failure rates from the tests, and the. number of anchors which were replaced, leave a small opportunity for inadequate baseplates, i

Anchor Bolt Testing Results Summary on Unit No. 2 i

Total number of baseplates 163 Number of basoplates tested 161 Total number of anchors 433 f

Number of anchors tested for preload 380 Number of anchors failed prolood 9

l Preload test failure rate 2.4%

i i

Number of ancuors not tested for preload

.53 Number not tested due to-frozen 1cveling nut 39 Number tested for other reasons 14 Number of anchors tested for embedment 254 l

Number of anchors with inadequata embedment 4

Embedment test failure rate 1.6%

f Number of anchors not tested for embedmont 179 l

Number not tested due to frozen leveling nut -

39 i

Number not tested due to frozen stud 117 i

Number not tested for other reasons 23 i

j Number of anchors tested for engagement 256 Number of anchors with inadequate engagement 4

Engagement test failure rate 1.6%

l Number of anchors not tested for engagement 177 Number not tested due to frozen leveling nut 39-Number not tested due to frozen stud 117 l

Number not tested for other reasons 21

-Total failure rate-5,6%-

[

- As required by. IE Bulletin 79-02, CP&L.has - completed the test program for Unit No.

2.- Unit-No. 1 testing.is essentially complete.

The results are being tabulated and checked to assure no identified supports-remain untested.

During the upcoming Unit No. 1 ot.tage scheduled to start in 4

September 1982, any supports not yet tested in the primary containment sill be-tested and results-transmitted to your office, t

i i

4

i Mr. O'keilly July 26, 1982 In ovr February 25, 1981 letter, we committed to performing a weld verification sampling program for seismic pipe supports as part of the Phase I program. We base completed this sampling program with greater than a 95 percent confidence level that the original QC inspection program was adequate.

This 95 percent confidence level it consistent with that required for the IEB 79-02 sampling programs and thus we believe our pipe support welds are acceptabic.

4 In conclusion, upon the completion of the long-term fixes discussed previously, the Pipe Stress Analysis Summary Tables will be updc*.ed to indi.: ate completion of the field modifications.

This update will signify our completion of work and compliance with the above bulletins. We anticipate this milestone will occur in mid-1983, at which time vou will be notified in writing.

Very truly yours,

" URIGINAL SIGNED BYj 4

4 C. R. "0 R. OlETZ-\\ DIc~tz, General Manager 3

Brunswick Steam Electric Plant JSB/dg i

cc:

Mr. R. C. DeYoung 23 bcc: Mr. D. L. Bensinger/ File: BC/A-4 Mr. L. H. Martin i

Mr. F. R. Coburn Mr. J. A. McQueen, Jr./ File: B-X-544 Mr. A. B. Cutter Mr. D. O. Myers Dr. T. S. Elleman Mr. C. H. Moseley Mr. B.

s.

Furr Mr. R. B. Stcrkey, Jr.

Dr. J. D. E. Jeffries Mr. L. V. Wagoner Mr. I. A. Johnsen Mr. J. L. Willis INPO Ms. M. S. Wingo Nuclear Operations File 13510(E) a 1

1 9

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