ML20106G009
| ML20106G009 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 11/16/1984 |
| From: | Con V, Le A CALSPAN CORP. |
| To: | Nilesh Chokshi NRC |
| Shared Package | |
| ML20106F973 | List: |
| References | |
| CON-NRC-03-81-130, CON-NRC-3-81-130 IEB-80-11, TAC-42876, TAC-42877, NUDOCS 8502140184 | |
| Download: ML20106G009 (30) | |
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ATTACHMENT 1 TECHNICAL EVALUATIO'N REPORT 4
MASONRY WALL DESIGN CAROLINA POWER AND LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT UNITS 1-AND 2
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w-FRC PROJECT C5506 NRC DOCKET NO. 50-325, 50-324 FRC ASSIGNMENT 6 NPC TAC NO. 42876, 42877 FRC TASK 245 NRC CONTRACT NO. NRC 03-81-130 Preparedby Author:
A. K. Le, V. N. Con Franklin Research Center 20th and Race Street FRC G/oup Leader:
V. N'. Con Philadelphia, PA 19103 Prepared for Nuclear Regulatory Commission Lead NRC Engineer: N. C. Chokshi Washington, D.C. 20555 November 16, 1984 This report was prepared as an account of work sponsored by an agency of the United States -
Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or impiled, or assumes any legal liability.or responsibility for any third party's use, or the results of such use, of any information, appa-ratus, product or process disclosed in this report, or represents that its use by such third party would notinfringe privately owned rights.
1 FRANKUN RESEARCH CENTER i
DIVISION OF ARVIN/CALSPAN 3
8502140184 850130 PDR ADOCK 05000324 G
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F TECHNICAL EVALUATION REPORT MASONRY WALL DESIGN CAROLINA POWER AND LIGHT COMPANY B'RUNSWICK' STEAM ELECTRIC PLANT UNITS 1 AND 2 -
NRC DOCKET NO. 50-325, 50-324 FRC PROJECT C5506 NRC TAC NO. 42876, 42877 FRC ASSIGNMENT 6 NRC CONTRACT NO. NRC 03-81-130 FRC TASK 245 R*
Preparedby Franklin Research Center Author:
A. K. Le, V. N. Con 20th and Race Street Philadelphia, PA 19103 FRG Group Leader:
V. N. Con Prepared for Nuclear Regulatory Commission
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Washington, D.C. 20555 Lead NRCEngineer: N. C. Chokshi November 16, 1984 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or impiled, or assumes any legal liability.or responsibility for any third party's use, or the results of such use, of any information, appa-ratus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.
Prepared by:
Reviewed by:
Approved by:
d$. h K %r len Vn %er la [ror 5*. Caj;po) c Principal Author:
Group Leader Department Director Date:
//- /d - 84 Date:
Il-Ib.1h Date:
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FRANKUN RESEARCH CENTER OlVl510N OF ARVIN/ CAL $ PAN 20th and Race Streets. Phila.. Pa. 19103 (215) 448 1000 1
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TER-C5506-245
' CONTENTS l
Section Title Page 1
INTRODUCTION 1
1.1 Purpose of Review.
1 1.2 Generic Issue Background 1
1.3 Plant-Specific Background.
1 2
EVALUATION CRITERIA.
3
.3 TECHNICAL EVALUATION
- 4 3.1 Evaluation of Licensee's Criteria.
4 3.2 Evaluation of Licensee's Approach to Wall Modifications 16 17
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4 CONCLUSIONS.
5 REFERENCES.
18 APPENDIX A - SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL.AND GEOTECHNICAL ENGINEERING BRANCH [SGEB] OF THE NRC)
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TER-C5506-245 FOREWORD This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Regulatory Commission (Office of 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 the NRC.
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TER-C5506-245 1.
INTRODUCTION
,1.1 PURPOSE OF-REVIEW l
l The purpose of this review is to provide technical evaluat; ions of Licensee responses to IE Bulletin 80-11 [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.
1.2 GENERIC ISSUE BACKGROUND In the course of conducting inspections at the Trojan Nuclear Plant, Portland General Electric Compa'ny determined that some concrete masonry walls did not have adequate structural strength. Further investigation indicated that the problem resulted from errors in engineering judgment, a lack of established procedures and procedural details, and inadequace design criteria.. Because of the implication of similar deficiencies at other operating 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
' criteria for the masonry walls with the analyses to justify those criteria.
If modifications were proposed, licensees were to state the methods and schedules'for the modifications.
1.3 PLANT-SPECIFIC BACEGROUND In response. to IE Bulletin 80-11, the Carolina Power and Light Company i
i (CP&L) provided the NRC with documents [2, 3, 4, 5] describing the status of l
masonry walls at the Brunswick Steam Electric Plant Units 1 and 2.
The j
information in these documents was reviewed, and a request for additional information was sent to the Licensee [6] to which the Licensee. responded [7].
- Numbers in brackets indicate references, which are cited in Section 5.
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TER-C5506-245 Additional questions [8] were sent to the Licensee, to which it has also responded [9].
.The Licensee 'dentified 87 masonry walls as safety-related for both Units 1
1 and '2.. Fourteen ire unreinforced walls and 18 are multiple-wythe walls.
j The masonry walls at the Brunswick plant function as partitions, fire 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 control panels, junction boxes, and light fixtures, is attached to walls throughout the plant.
Masonry wall types and materials for the Brunswick plant are given below.
Wall Types:
v Safety-related walls 87 7
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 Hollow load-bearing partitions and walls C90 Grade N-I C129 Solid units Cl45 Grade N-I Reinforcement ASTM 615-68 Grade 60 for sizes No. 6 to No. 11, and Grade 40 for smaller sizec.
Wire for Reinforcement Standard Dur-O-Wal galvanized spaced at every second course 1
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Y TER-C5506-245 2.
EVALUATION CRITERIA l
The basic documents used for' guidance in this review were the criteria developed by the Structural Geotechnic'al Engineering Branch (SGEB) of the NRC i
(attached as Appendix A to this report), the Uniform Building Code [10), and l
ACI 531-79 [11).
In general, the materials, testing, analysis, design, construction, and inspection of safety-related concrete masonry walls should conform to the SGEB criteria. For operating plants, the loads and load combinations for quali-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 appropriate increase factors for abnormal and extreme environmental loads are given in the SGEB criteria (Appendix A).
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TER-C5506-245 j-3.
TECHNICAL EVALUATION This evaluation is based' on the Licensee's earlier responses [2, 3, 4, 5) and subseq6ent 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.
3.1 EVALUATION OF LICENSEE'S CRITERIA The Licensee reevaluated the masonry walls using the following criteria:
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o Allowable stresses are consistent with ACI 531-79.
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o Load combinations are according to the FSAR.
l o The working s' tress design method is used.
l o The following damping values were used:
Unreinforced Walls 24 - Operating basis earthquake (OBE) 44 - Safe shutdown earthquake (SSE)
Reinforced Walls 44 - OBE 74 - SSE
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o The walls are modeled as beams or plates.
l o The typical analytical procedure is summarized belows i
- 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 l
have been reviewed and found to be technically adequate and in' compliance with the SGEB criteria. The review of the Licensee's response to the request for' additional information follows. ;
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TER-C55C6-245 l
Question 1 Indicate whether the walls have stack bond or running bond.
If any stack bond wall exists, prov,ide sample calculations to obtain moment and shear l'
etress of a typical wall.
Response 1
-The Licensee confirmed that there are no stack bond walls at the Brunswick plants all walls have running bond construction.
The Licensee's response has resolved the concern on stack bond construc-tion at the Brunswick plant.
Question 2 Indicate how frequency va intions due to uncertainties in mass, materials, and other. parameters were considered; Response 2 The Licensee indicated that the frequency variations due to uncertainties
-in mass, material, and other parameters were accounted for by varying the modulus of elasticity, En, between 1000 f's and 600 f's for hollow masonry and between 1200 f's and 800 f's for solid or grouted masonry.
As a result of modulus of elasticity variation, the wall's frequency will vary accordingly and the peak acceleration from the amplified 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 Licensee indicated that the in-plane interstory drif t was considered by comparing the in-plane strain induced in the wall to the in-f ane strain l,
TER-C5506-245 i
limits. For unconfined walls, this limit is 0.0001, and for confined walls j
bounded on top and bottom or bounded on three sides, the following formula was applied
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1 + [B/El 2000 B/H
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where B = wall width and H = height.
For confined walls at this plant, the smallest value for B/H is 0.667, which 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 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 available test data and it is judged to be adequate and satisfactory.
j Request 4 Indicate if cracking of sections was given proper consideration in the j
analysis.
j Response 4 The Licensee indicated that cracking is not permitted in unreinforced masonry walls. For reinforced masonry walls, cracking was properly accounted for in both frequency and strength calculations. Frequency variations which account for cracking were considered by calculating the effective moment cif 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 satisfactory.and in compliance with the SGEB criteria.
Question 5 Indicate whether the block pullout was considered in the evaluation. If
'yes, provide ' sample calculations of block pullout analysis W
TER-C5506-245 Response 5 The Licensee stated that. block pullout was considered in the evaluation of masonry walls. The sample calculation was provided for an 84in single-
. wythe wall.
The pullout strength was f,ound to be 6200 lb for unreinforced block and 51,000 lb for reinforced block. There were no attachment 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 excess of the pullout strength.
The Licensee's response is adequate and in compliance with the SGEB criteria.
Question 6 a.
In Reference 3, the Licensee indicated that loads and load combinations are based on the NRC Standard Review Plan for the b
elastic design method. The Licensee is requested to clarify whether i
they are consistent with the Plant Final Safety Analysis Report (FSAR).
If any deviations exist, justification should be given.
b.
With reference to load combinations, the Licensee is requested to i
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 DBE seismic plus abnormal temperature loads.
I 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 illustrat'ing how these loads were treated in the analysis, i
Response 6 i
a.
With regard to loads and load combinations, the Licensee confirmed l
that the load combinations are consistent with those in the Plant Final Safety Analysis Repo'rt (FSAR).
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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, the wall would not experience thermal-induced flexural ~or shear stresses.
c.
With regard to walls subjected to impact 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 j
protected by a 1/4-in steel plate attached by through bolting with l
3/4-in diameter bolts. The following are commitments related to potential missiles generated by the air receivers that exist in each l
of the diesel generator rooms between 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.
h; Case 2 - The air receiver is punctured and bec,omes a jet-propelled
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Case 3 - The air receiver explodes into fragments. A fragment is idealized as a 2-in-diameter circular disc.
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.i The sample calcualtion for case 1 was illustrated. The Licensee stated I
j that this was the most severe missile impact case and enveloped that 1
associated with case 3.
For case 2, a puncture in the most severe location
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was postulated and the Licensee stated that attachment and supports of the air receivers were adequate to prevent impact on the masonry walls.- Therefore, no impact calculations were performed for case 2.
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The sample calculation indicated that a penetration thickness-of 0.12-in is less than the thickness provided by the steel plate which is 0.25 in.
The overall stability of the wall, which is subject to the same postulated missile as case 1, was checked by comparing the calculated ductility ratio with the allowable ductility ratio. The calculated ductility ratio of the wall was found to be 3.7, which is smaller than the allowable ratio of 10.
The Licensee's response is judged to be adequate.
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l TER-C5506-245 Question 7 Show, by sample calculation, how the effect of higher modes of vibration
-was conside' red in the analysis.
Respon'se 7 The Licensee referred to a.' study contained in the " Recommended Guideline for the Reassessment of Safety Related Masonry Walls," dated October 6, 1980 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, highe'r 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 adequete and in compliance with the SGEB criteria.
Question 8 Indicate whether the construction practice for the masonry walls at the Brunswick plant was in conformance with the provisions specifiad for the special inspection category in ACI 521-79 [8].
If not, explain and justify the use of allowable stresses.
I Response 8 With regard to the construction practice, the Licensee indicated that a daily inspection by the superintendents for the subcontractor, contractor, and j
owner was performed during the construction of the masonry walls, j
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 constructed.
In addition, some tests were conducted to verify the allowable s'trength of the walls being analyzed. See Response 9.1 for more details of the laboratory test results to verify the assumed values of masonry and mortar strength used in the analysis.,
6 TER-C5506-245-4
. Question 9 With respect to Tables A-2 and A-3 [3], justify the use of _.the following
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increase for factored' loads (the _ increase factors allowed in the SGEB
- crite.ria [6] ar,e. shown in parentheses) :
shear in flexural members 1.5 (1. 3')
tension normal to the bed joint 1.67 (1.3) tension parallel to the bed joint 1.67 (1.3)
If the Licensee intends to use any existing test data to justify these factors, the Licensee is requested to discuss the applicability of these tests to the masonry walls at the plant to the following areas:
i o nature of loads o boundary conditions o materials used o size of test walls.
Response 9 The Licensee indicated that the increase factors 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, Berkeley. The Licensee stated that these test results were used as a comparison with the code allowables. See further details relative to this subject in Response 9.3.
Question 10 In Reference 3, the Licensee indicated that the energy balance technique and arching theory have been used to qualify some masonry walls. The NRC, at present, does not accept the application of.these techniquer to masonry walls in nuclear power plants in the absence of conclusive evidence to justify this application. The Licensee is requested to
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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 an'y conclusion can be made about these techniques:
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Energy Balance Technique o For the walls which were analyzed by using the energy balance technique, provide the, technical basis to ensure that the ductile mode of failure will take place (if they fail).
o Provide justificati'on' and test data (if available)'lto validate the
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applicability.of the. energy balance technique to the masonry structures at Bruns' wick Units 1 and 2 with particular emphasis on the following areast a.
nature of the load b.
boundary conditions c.
material strength d.
size of test walls.
2.
Arching Theory o Explain how the ar.ching theory handles cyclic loading, 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 structures at Brunswick Units 1 and 2 with particular emphasis on the following areas:
5 a.
nature of the load b.
boundary conditions c.
material 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 shear failure might take place. This in-plane shear force would j
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also reduce the out-of-plane stiffness. Explain how the effect of this phenomenon can be accurately determined..
Response 10 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.,
TER-C5506-245 Response 11 See Response 9.5.
duestion12 With reference to the multiple wythes, clarify whether the collar joint strength was used in the analysis.
If so, justify the allowable stresses of.the colfsr joint.. Also, provide sample calculations illustrating the analysis.oi multiple-wythe walls.
l Response 12 i
The Licensee stated that the composite action was not used in the
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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 multiple-wythe walls as follows:
For Unit 1, the wall is 8 ft 8 in long, 16 ft 4 in high, and 2 ft 0 in thick (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 wythes 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 of 0.28 g for BE and 0.435 g for SSE, th6 calculated flexural stress and shear stresses were found to be 27 psi, and 1.3 psi, which are smaller than the allowable stresses of 75 psi and 47 psi for OBE.. The calculated flexural and shear stresses for SSE were found to be 43 psi and 2 psi, which are smaller than the flei.dral and shear allowable stresses of 125 psi and 72 pai, respectively.
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 and shear stresses were found to be 16 psi and 1.2 psi, which are smaller than the allowable stresses of 75 psi and 47 psi for OBE. The calculated flexural me h--e+-sv
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TER-C5506-245 and shear stresses for SSE were found to be 28 psi and 2 psi, which are smaller the flexural and shear allowable streses of 125 psi and 72 psi,
. respectively.
The Licensee's response is adequate and in compliance wit SGEB criteria.
Question 13 Provide detailed drawings and current status of proposed repairs. Also, provide a sample calculation to illustrate that the modified walls will be qualified under the working stress design condition.
Response 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 4a at elevation 5 ft 0 in in the diesel generator building. The wall is reinforced filled wall, 8-in thick.
Structural steel member W8 x 31 was attached to one side of the wall at 25 ft 6 in maximum spacing with two 3/4-in throughbolts at 16-in spacing. Also, restraint angles were installed on top of walls. These modifications make the wall behave as a plate.
A review of the sample calculation indicated that the calculated stresses are within the SGEB code allowable. Therefore, the Licensee's response is considered adequate and in compliance with the SGEB criteria.
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 cross-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..
TER-C5506-245
-If joint reinforcement is used to resist tension, it should follow the L
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, identify all affected walls along
.with the. calculated stress value for each wall.
Indicate if there is any wall that has-only joint' reinforcement (horizontal reinforcement), no vertical reinforcement, and may have been qualified using the tensile resistance of the; joint reinforcement. It
.should be noted that the NRC, at present, does not approve the use of joint reinforcement to qualify this type of wall.
Indicate all walls belonging to this category.
i Response 9.1
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1 With regard to the minimum area of reinforcement, the Licensee confirmed that the reinforced walls at the Brunswick plant meet the requirements of ACI 531-79 with regard to the minimum area of reinforcement.
The Licensee also clarified that horizontal joint reinforcing was not used to resist tension in evaluating masonry walls; therefore, no walls were qualified using the tensile resistance of the jo' int reinforcing.
The Licensee's response is satisfactory and in compliance with the SGEB
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criteria.
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Question 9.2 Regarding f.esponse 8 of Reference 2, please provide laboratory test results to verify the assumed values of masonry and mortar strength used I
in the analysis.
Response 9.2, With regard to the test results of masonry blocks, the Licensee referred l
to tests performed by Pittsburgh Testing Laboratory for the two-core hollow load bearing block and the 100% solid block.. The test results'for the
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two-core hollow load-bearing block indicated an average strength of 1520 psi j
compared with the ASTM C90-70 compressive strength.of 1000 psi.
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.
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TER-C5506-245 the following ASTM Standards: ASTM C91, ASTM C144, ASTM C270, ASTM C476, and ASTM C780.
The Licensee's response is considered adequate.
Question 9.3 8
With respect to the increase factors for load combinations containing SSE or accident load case [2], please identify all walls that would not be 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.
Response 9.3 The Licensee stated that all walls qualify when the SGEB criteria is used, except walls 8a and 8b in the reactor building, which are unreinforced 4-f t-thick multiple-wythe walls. Walls B'a and 8b would not be qualified if the SGEB criteria were to be used on a single 8-in wyt,he; however, they do 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 OBE 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 SGEB criteria.
Question 9.4 With regard to wall modifications, 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 deccription 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 SGEB code.
TER-C5506-245
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requirements.
In addition,-the Licensee is currently evaluating 17 additional j
wall's for which a determination as to the. necessity of a fix has not yet been made. The implementation of any necessary repairs for any additional walls j
resulting from evalyation of the 17 walls will be scheduled when and if such repairs are ascertained to be required. The types of modifications to be
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implemented include the addition of steel plasters, a steel grading restraining wall, and steel angles installed at the boundary.
Because the Lice'nsee has made a commitment to modify walls so that they' l
are in compliance with the SGEB criteria, this change should be acceptable.
Question 9.5 With regard to the nonlinear analysis technique (energy balance technique and arching action theory.), please note the following information a.
Arching Action: The NRC position on this issue states that the use of the arching action theory to qualify unreinforced masonry walls is not acceptable; these walls should be repaired so'that they can be qualified based on the SGEB criteria (3].
(The NRC position is j
attached.)
l b.
Energy Balance Techniques The NRC is currently preparing a position J
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statement regarding this technique, which will be. forwarded to the Licensee in the near future.
Response 9.5 See Response 9.4.
3.2 EVALUATION OF LICENSEE'S APPROACH TO WALL MODIFICATIONS 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 SGEB criteria.
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TER-C5506-245 4.
CONCLUSIONS s
A detailed study was performed to provide a technical evaluation of the masonry walls at the Brunswick Steam Electric Plant Units'l 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 criteria are in compliance with the SGEB 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 implementd., The Licensee's approach to wall modification
. is jtidged to be satisfactory, and the modified walls were verified through samplecalculationstobestructurallyadNuateandincompliancewiththe SGEB criteria.
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REFERENCES 1.
IE Bulletin 80-11 Masonry Wqll Design NBC, 08'-May-80 2.
B. J. Furr i
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 7,1980 NO-80-1009 3.
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 (180-Day l
Response) (Attached)
Carolina Power & Light Co., November 5,1980 NO-80-1632 4.
B. J. Furr Letter to J. P. O'Reilly, NRC.
Subject:
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:
Brunswick Steam Electric Plant, bait Nos.1 and 2 - Supplemental Response to IE Bulletin 80-11 Carolina Power & Light Co., December 9,1980 NO-80-1739 6
D. B. Vassallo, NRC Letter to S. R. Zimmerman, CP&L
Subject:
Brunswick Steam Electric Plant, Unit Nos. 1 and 2 - IE Bulletin 80-11, Masonry Design - Request for Additional Information August 2, 1982 7.
S. R. Zimmerman, CP&L Letter to D. B. Vassallo, NRC Subj ect:
Brunswick Steam Electric Plant, Unit Kos. 1 and 2 - IE Bulletin 80-11, Masonry Design - Response to Request for Additional Information July 29, 1983 8.
D. B. Vassallo, NRC Letter to S. R. Zimmerman, CP&L
Subject:
Brunswick Steam Electric Plant, Unit Nos. 1 and 2 - IE Bulletin 80-11, Masonry Design - Request for Additional Information February 21, 1984
TER-C5506-245 9.
A. B. Cutter, CP&L Letter to D. B. Vassallo, NRC Subject Brunswick Steam Electric' Plant, Unit Nos.1 and 2 - IE Bulletin 80-11, Masonry Design - Request for Additional Information April 27, 1984
- 10.
Uniform Building Code International Conference of Building Officials,1979 '
11.
Building Code Requirements for Concrete Masonry Structures Detroit: American Concrete Institute, 1979 ACI 531-79 and ACI 531-R-79 12.
NCMA - Specification for the Design and Construction of Load Bearing Concrete 4
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APPENDIX A I
SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRNRAL AND GEOTECHNICAL ENGINEERING BRANCH (SGEB] OF THE NRC) 4 1
FRANKUN RESEARCH CENTER DIVISION OF ARVIN/CALSPAN 20th and Race Streets. Phila., Pa.19103 (215) 448 1000
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P TER-C5506-245 CONTENTS
. Section Title Page A-1 1
GENERAL REQdIREMENTS 2
LOADS AND LOAD COMBINA0 IONS.
A-1 a.
Service Load Combinations A-1 b.
Extreme Environmental, Abnormal, Abnor:nal/ Severe Environmental, and Abnormal / Extreme Environmental Conditions.
'A-2 3
ALLOWABLE STRESSES.
A-2 4
DESIGNANDANALYSISdONSIDERATIONS.
A-3 5
REFERENCES.
A-4 O
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TER-C5506-245 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 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 these codes are less conservative than the corresponding 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 these criteria. Plants which are applying for an operating license and which have already built unreinforced masonry walls will be evaluated on a case-by-case basis.
2.
Loads and Load Combination's The loads and load combinations shall include consider tion of normal loads, severe environmental loads, extreme environmental loads, and, abnormal. loads.
Specifically, for operating plants, the load combinations provided in the plant's FSAR shall govern. 'For operating license applications, the following load combinacions 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 l
(3) D + L + W o and Ro are present, they should be If thermal stresses due to T 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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TER-C5506-245
. b)- Extr'eme Environmental, Abnormal, Abnormal / Severe Environmental, and
(
Abnormal / Extreme Environmental Conditions (4) D + L + To + Ro + E.
(5) D + L + 1h3 + Ro + Mt (6) D + L + Ta+Ra + 1.5 Pa (7) D + L + Ta+Ra + 1.25 Pa + 1. 0 (Yr + Yj + Y ) + 1.25 E m
(8) D + L + Ta + Ra + 1.0 Pa + 1.0 (Yr + Yj + Y,) + 1.0 E' In combinations (6), '(7), and (8) the maximum values of P, T '
a a
Rs Yj, Yr, and Y,,
including an appecpriate dynamic load a
factor, should be used unless a time-history analysis is performed to justify otherwise. Combinations (5), (7), and (8) and the corresponding structural acceptance criteria should be satisfied first without the tornado missile load in (5) and without Y, Yj, r
and Y in (7) and (8)".
When considereing these loads, local a
section strength capacities may.be exceeded under these concentrated loads, provided there will be no loss of function of any safety-related system.
- Both cases of L having its full value or being completely absent should be checked.
3.
Allowable Stresses Allowable, stresses provided in ACI-531-79, as supplemented by the 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 category shall be substantiated by demonstration of compliance with the inspection requirements of the SEB criteria.
(c)
When tension perpendicular to bed joints is used in qualifying the-unreinforced masonry walls, the allowable value will be justified by
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test program or other means pertinent to the plant and loading l
conditions. For reinforced masonry walls, all the tensile stresses j
will be resisted by reinforcement.
l (d)
For load conditions which represent extreme environmental, abnormal, i
abnormal / severe environmental, and abnormal / extreme environmental conditions, the allowable working stress may be multiplied by the factors shown in the following tables A-2
TER-C5506-245 Type of Stress Factor Axial or Flexural Compression 2.5
. nearing, 2.5 Reinforcement stress except shear 2.0 but not to exceed 0.9 fy Shear reinforcement and/or bolts 1.5 Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular to bed joint for reinforced masonry 0
2 1.3 for unreinforced masonry Notes
ll)
When anchor bolts are used, design should prevent facial spalling of masonry unit.
(2)
See 3(c).
4.
Design and Analysis Considerations
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(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 structural requirements of FSAR shall apply. For other plants, corresponding SRP requirements shall apply. The seismic analysis 2
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 drif t effects should be considered.
l A-3
.,,,. - ~ -,., -. - - -,,, -,, -
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l TER-C5536-245 (g)
In new construction, grout in concrete masonry walls, whenever used, shall be compacted by vibration.
I (h)
For masonry shear walls,- the minimum reinforcement requirements of ACI-531 shall apply.
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(i)
Special constructions '(e.g., multiwythe, composite) oh other items not covered by the code shall be reviewed on a case-by-case basis for their acceptance.
(j)
Licensees or applicants shall submit QA/QC information, if available, l
for staff's review..
i 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
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to ascertain the conformance of masonry construction to design drawings and specifications (e.g., rebar and grouting).
(k)
For masonry walls requiring protection from spalling and scabbing due to accident pipe reachion (Yr), jet impingement (Yj), and missile j
impact (Y,), the requirements similar to those of SRP 3.5.3 shall apply. However, actua3 review will be conducted on a case-by-case basis.
5.
References (a)
Uniform Building Code - 1979 Edition.
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(b)
Building Code Requirements for Concrete Masonry Structures ACI-531-79 and Commentary ACI-531R-79.
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(c)
Tentative Provisions for the Development of Seismic Regulations for
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Buildings - Applied Technology Council ATC 3-06.
(d)
Specification for the Design and Construction of Load-Bearing
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Concrete Masonry - NCMA August, 1979.
(e)
Trojan Nuclear Plant Concrete Masonry Design Criteria Safety l
Evaluation Report Supplement - November,1980.
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