ML20210C299
| ML20210C299 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 03/20/1986 |
| From: | Carfagno S, Con V, Triplo S CALSPAN CORP. |
| To: | NRC |
| Shared Package | |
| ML20210C305 | List: |
| References | |
| CON-NRC-03-81-130, CON-NRC-3-81-130 IEB-80-11, TAC-42902, TER-C5506-263, NUDOCS 8603240120 | |
| Download: ML20210C299 (28) | |
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FRANKLIN RESEARCH CENTER DIVISION OF ARVIN/CALSPAN e
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J TECHNICAL REPORT ii 20TH & RACE STREETS PHILADELPHIA.PA 19103 TWX 710 670-1989 TEL (215)4481000 8603&fo/42o X&
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TECHNICAL EVALUATION REPORT NRC DOCKET NO. 50-302 FRC PROJECT C5506 NRCTAC NO. 42902 FRC ASSIGNMENT 6 NRC CONTRACT NO. NRC 03-81130 FRC TASK 263 i
MASONRY WALL DESIGN l
FIORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 1
TER-C5506-263 3[
Prepared for Nuclear Regulatory Commission FRC Group Leader: v. Con Washington, D.C. 20555 NRC Lead Engineer: N. C. Chokshi
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.' - t March 20, 1986 This report was prepared as an account of work aponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their l
employees, makes any warranty, expressed or implied, 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:
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Date:
FRANKLIN RESEARCH CENTER OfVISION OF ARVIN/CALSPAN sotn s eAca staseTs.puuAostriaA.pa mos
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TER-C5506-263 CONTENTS Section Title P3ge 1
1 INTRODUCTION 1
1.1 Purpose of Review.
i 1
1.2 Generic Issue Background 1
1.3 Plant-Specific Background.
3 2
EVALUATION CRITERIA.
4 3
TECHNICAL EVALUATION 4
3.1 Evaluation of Licensee's Criteria.
f 3.2 Evaluation of Licensee's Approach to Wall Modifications 15 jf 16 4
CONCLUSIONS.
I 17 5
RErERENCES.
7 APPENDIX A - SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GEOTECHNICAL ENGINEERING BRANCH [SGEBj OF THE NRC) lJ a
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TER-C5506-263 FOREWORD This Technical Evaluation Report was prepared by Franklin Research Center
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under a contract with the U.S. Nuclear Regulatory Comission (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
,a the NRC.
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i TER-C5506-263 1.
INTRODUCTION 1.1 PURPOSE OF REVIEW The purpose of this review is to provide technical evaluations 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.
l.2 GENERIC ISSUE BACKGROUND J
In the ceurse of conducting inspections at the Trojan Nuclear Plant, l
Portland General Electric Company determined that some concrete masonry walls 3'
9 did not have adequate structural strength. Further investigation indicated that the problem resulted from errors in engineering judgment, a lack of f~
established procedures and procedural details, and inadequate design
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criteria. Because of the implication of similar deficiencies at other operating plants, the NRC issued IE Bulletin 80-11 on May 8, 1980.
FI 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.
j If modifications were proposed, licensees were to state the methods and schedules for the modifications.
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a 1.3 PLANT-SPECIFIC BACKGROUND In response to IE Bulletin 80-11, Florida Power Corporation (FPC) i provided NRC with letters and attachments dated July 7, 1980 [2], November 7, I
1980 [3], November 17, 1980 [4], and March 23, 1982 [5] describing the status of masonry walls at Crystal River Unit 3.
This information was reviewed, and i
several unresolved issues were identified.
On November 19, 1983, a request for additional information was sent to the Licensee, which responded in a submittal dated February 29, 1984 [6].
I Another request for information was sent on August 26, 1985, and the Licensee
- Numbers in brackets indicate references, which are cited in Section 5.
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TER f.:5506-263 responded by submittal dated November 25, 1985 [7].
Based on the information supplied by the Licensee, a review of the masonry walls at the Crystal River plant was conducted.
The Licensee has identified five walls in the control complex building at the Crystal River plant as safety-related. These walls function as partitions. There are three walls in the instrument room of the turbine building, a non-safety-related structure, which were also evaluated as a a
result of the upgrade to the emergency feedwater system.
Typically, the safety-related walls at the Crystal River plant are single-wythe, hollow construction and are vertically unreinforced. Thickness a
is either 6 or 8 inches.
.d The materials used in construction are as follows:
Hollow units: ASTM C90-66T, Grade G-ll, minimum compressive strength g]
(f'm) of 1200 psi Horizontal reinforcing: Dur-O-Wal standard welded steel !!o. 9 rod
,r-reinforcing l[;
Mortar: ASTM C270-64T, Type N, minimum compressive strength (m ) of o
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750 psi
.J With the exception of Wall 1 in the control complex, all safety-related masonry walls at this plant were qualified without modification using the a
Licensee's acceptance criteria. Wall 1 was modified by the removal of a j
portion of the wall. This will be discussed further in Section 3.
Stress analysis of the walls was performed using the working stress l
method. No inelastic methods of analysis were used to evaluate walls at the Crystal River plant.
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TER-C5506-263 2.
EVALUATION CRITERIA The basic docurnents used for guidance in this review were the criteria developed by the Structural and Geotechnical Engineering Branch (SGEB) of the NRC (attached as Appendix A to this report), the Uniform Building Code [11],
and ACI 531-79 [12).
The materials, testing, analysis, design, construction, and inspection of f
safety-related concrete masonry structures should conform to the SGEB criteria.
For operating plants, the loads and load combinations for qualifying the masonry walls should conform to the appropriate specifications in the Final Safety Analysis Report (FSAR) for the plant. Allowable stresses are specified "I
n in Reference 12, and the appropriate increase factors for abnormal and extreme
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d environmental loads are given in the SGEB criteria (Appendix A).
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TECHNICAL EVALUATION i
9 This evaluation is based on the Licensee's earlier responses [2, 3, 4, 5], and subsequent responses [6, 7] to the NRC requests for additional information. The Licensee's. criteria were evaluated with regard to design and analysis methods, loads and load combinations, allowable stresses, construction specifications, materials, and any relevant test data.
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3.1 EVALUATION OF LICENSEE'S CRITERIA TheLicenseeevaluatedthemasonrywallsusingthe[o11owingcriteria:
i Allowables stresses are based on ACI 531-79, with the exception of o
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the allowable compressive stress which,was taken from the Southern a
Standard Building Code (SSBC).
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Load combinations are according with the (FSAR).
o The following damping values are used:
1 2% for the operating basis earthquake (OBE) d 5% for the safe shutdown earthquake (SSE).
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o The working stress method of analysis was used.
A typical analytical procedure used in the working stress design o
method is, summarized below:
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- determine wall boundary conditions
- calculate the wall's fundamental frequency
- obtain inertial loading from the floor response spectra
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- compute stresses using SAP IV and a multi-mode analysis compare calculated stresses to allowables.
- L' The Licensee's criteria and responses [6, 7] have been reviewed. Other than t$.ase areas identified in Section 4, the Licensee's criteria have been found to be adequate and in compliance with the SGEB criteria (Appendix A).
Following is a review of the Licensee's responses in References 6 and 7.
Questions and responses covering the same topic have been combined:
1 5
1 i
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TER-C5506-263 Question 1 Provide and justify the reasons for not considering tornado loads in the analysis.
Indicate if walls are subject to missile impact (both internal and external).
If so, provide sample calculations (and, if necessary, provide explanations to make the calculations understandable).
Response 1 The Licensee responded that five walls were interior to the control complex. The control complex was designed to resist tornado loads and tornado-generated missiles; therefore, these interior walls are sheltered from i
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tornado missiles and will not be subjected to tornado-related pressure loads.
The turbine building, which was not designed specifically for tornadoes,.
' 'l contains walls that will be exposed to tornado effects. However, these walls 1
are not safety-related with respect to tornado loads because the emergency feedwater components near these walls do not have to be protected from q
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tornado-induced failure since there is an alternate emergency feedwater source, which is already protected from tornado effects.
The response is adequate and satisfies the SGEB criteria.
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9 Question 2 Justify the use of an allowable stress increase factor of 1.67 for load h
combinations containing accident pressure for SSE loads. This is in i LJ excess of several factors permitted by the SGEB criteria (1); they are listed below by type of stress:
1,3 masonry shear in flexural members 1.3 masonry shear in unreinfored shear walls 1.3 reinforcement takes entire shear 1.5
,i tension normal to bed joint 1.3 tension parallel to bed joint 1.5 If any existing test data will be used to justify this increase factor, discuss the applicability of these tests to the walls at the Crystal River plant with particular emphasis on the following:
boundary conditions i
nature of loads i
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TER-C5506-263 i
size of test walls type of masonry construction (block or mortar type grouted or ungrouted).
l The Licensee is also requested to identify walls that would not be qualified if the SGEB criteria were to be used and to specify the percentage of exceedance. The Licensee is advised to explain all conservative measures (if any) used in the analysis to justify this increase factor.
l Response 2 In this response, the Licensee indicated that the 1.67 factor was chosen s
j as the working stress equivalent to the ultimate strength requirement of ACI L
318-63. This factor cannot be justified without adequate test data however,
'1 the walls were reevaluated, using the SGEB increase factors. As a result of I
this reevaluation, the Licensee concluded that walls 1, 2, and 3 in the
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control complex did not meet the NRC criteria. Wall I has been modified to d
eliminate the danger to safety-related equipment (see Section 3.2).
A recent i
inspection of walls 2 and 3 indicated that the failure of these walls does not, in fact, pose a threat to safety-related equipment in the area (see Response 15). Walls 4 and 5 met the SGEB criteria with the following exception: The Southern Standard Building Code was used for the allowab".c.
i, axial compressive stress (see Response 16 and Section 4 for further l
discussion). The Southern Standard Building Code value for allowable compressive stress is 70 psi for partition walls, whereas the maximum 1;
allowable by ACI 531-79 is 120 psi (based on f'm = 700 psi). Also, the d
theoretical buckling strength of the critical wall, using a factor safety of 9, results in an allowable compressive stress of about 90 psi. Therefore, the Southern Standard Building Code value is acceptable. The instrument room walls in the turbine building satisfied the SGEB criteria.without any
't limitations.
This response is adequate and in compliance with the SGEB criteria.
4 Question 3 With reference to the reinforcement in masonry walls, the ACI 531-79 Code 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 horizontal, shall not be less than 0.002 (0.2%) times i !
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TER-C5506-263 the gross cross-sectional area.
It should be noted that the horizontal reinforcement is installed to satisfy the minimum reinforcement requirement for a reinforced wall.
With reference to the joint reinforcement, identify the walls qualified by the tensile strength of joint reinforcement and indicate the type of spacing of the joint reinforcement for each wall.
Based on the review of existing codes and published literature, the NRC does not, at present, alpove the use of joint reinforcement as a structural element.
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Response 3 l
The Licensee responded that, at most, the walls at the Crystal River plant contain Dur-O-Wal in the horizontal joints spaced at 16 inches on center. This definitely does not meet the minimum reinforcing requirements
,y for reinforced walls. However, the reevaluation of the walls at this plant considered them as unreinforced and was based on unreinforced masonry requirements. The tensile strength of the joint reinforcement was not used to
!p qualify the walls.
This response is satisfactory and complies with SGEB criteria.
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Question 4
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Indicate the boundary conditions used in the analysis and verify that
'gj they resemble the real physical conditions.
Identify all of the mechanisms used to transfer shear and moment (if any).
If any doubt exists (i.e., whether simply supported or fixed-end conditions should be 4
-j assumed), verify that the assumed boundary conditions will produce conservative results, R_esponse 4 u
The Licensee indicated that boundaries were considered fixed, pinned, or free. At mortared bases or along vertical edges that are integral with other walls, the boundary was assumed to be fixed although no anchors or dowels exist to transfer moment across the boundary. Justification for fixed conditions on walls 1, 2, and 3 are unnecessary since these walls were already I
found to be overstressed and their qualification does not depend on stress
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criteria; wall I has been modified so that its failure would not harm i
safety-related equipment, and the failure of walls 2 and 3 has been found to l 4
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l TER-C5506-263 not have an adverse effect on equipment. Walls 4 and 5 in the control complex were initially evaluated using fixed boundaries along the sides and at the base. However, these walls have been reevaluated using plate solutions for a uniformly loaded plate with pinned edge conditions:
the stress levels remained within the acceptable limits.
The Licensee's boundary assumptions are considere,d adequate and satisfy the SGEB criteria.
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Question 5 e.
i Indicate how interstory drift effects, both in-plane and out-of-plane, J
were considered in the analysis. Also, indicate and justify by available test data the permissible strains used for both confined and unconfined
.,l walls.
U Response 5 l.h
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The Licensee indicated that the walls at the Crystal River plant were
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evaluated for in-plane interstory drift effects using the strain criteria
\\J discussed in Reference 8.
Allowable in-plane strain was 0.0001 for unconfined i
walls and 0.001 for confined walls.
Out-of-plane interstory drift effects were evaluated by calculating the flexural stresses developed by the relative displacement and comparing them to the ACI 531-79 allowables. None of the 1
walls exceed the allowable limits for interstory drift.
J This response is adequate and satisfactory.
9 Question 6 Indicate whether concrete block walls are stacked or running bond.
If any stack bond wall exists, provide sample calculations for stresses in a o
typical wall. Also identify the number of stacked bond walls and their appropriate allowable stresses.
Response 6 The Licensee responded that all masonry walls are running bond.
f Question 7 i
In Section 3.5.1 of Reference 3, it is indicated that the computed stresses are increased 5% to account for higher modes of vibration. Justify by sample calculation that 5% is an appropriate percentage of multimode effects.
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TER-C5506-263 Response 7 In this response, the Licensee indicated that only the instrument room walls used the 5% increase to account for multi-mode effects. The five walls in the control complex were evaluated using a multi-mode analysis considering the first eight modes of vibration.
It has been observed in other plants that the first mode contributes 95% or higher to the response. Therefore, the Licensee's consideration of multi-mode effects is adequate.
This response satisfies the SGEB criteria.
l li-Question 8 Provide sample calculations (with explanations necessary to make the calculations understandable) for:
.u a single-wythe wall analysis H_
tornado loads available (if applicable).
f Response 8 The Licensee responded that no tornado analysis was required (see Response 1).
A sample calculation was provided for wall 3 in the control complex, illustrating the analysis for the governing SSE horizontal in l
combination with SSE vertical. This calculation used a 50-lb weight per square foot of wall surface for an 8-inch block. The SAP IV computer program 9
was used to determine the inertial response and the resulting stresses in the wall. A flexural tensile stress of 80.9 psi was found normal to the bed joints. This, compared with the ACI allowable of 13.7 psi multiplied by the n
L SGEB increase factor of 1.3, indicated that wall 3 does not meet the SGEB s
criteria with respect to flexural stress. However, a recent inspection has shown that the failure of this wall, as well as wall 2, would not adversely affect safety-related equipment (see Response 15).
This response is satisfactory.
Question 9 Indicate how the uncertainties due to variations in mass, material, and section properties were accounted for in the analysis.
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TER-C5506-263 Response 9 The Licensee responded that uncertainties due to variations in mass, material, and section properties in walls, 1, 2, and 3 of the control complex were accounted for in the design floor response spectrum. This curve envelopes the floor response curves obtained by dynamic analysis. This enveloping offsets any uncertainties that may exist in the material properties of the wall. The design responses of the instrument room walls and walls 4 i
and 5 of the control complex were obtained from the design ground response spectra (walls are below grade elevation of 118 ft 6 inches) using standard methods, and show the smooth, broad band response spectra required to account I
for uncertainties. Reasonable uncertainties in mass, material, and section properties will have a small effect on wall spectral acceleration.
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This response is adequate.
A-Question 10
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Reference 4 indicated that several areas of the plant, such as the containment, the waste gas storage tank room, the spent resin storage
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tank room, the deborating demineralized room, the cation deminoralizer room, and the air shaft, werc inaccessible. Confirm whether a field f
survey has been conducted to verify that no safety-related equipment is jeopardized by masonry walls in these areas according to construction drawings.
If any discrepancy exists, provide explanations and/or remedial actions and a schedule of completion.
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Response 10 j
d The Licensee responded that all available documentation indicates that
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there are no masonry walls in the containment building, waste gas storage tanx
,I room, deborating domineralizer room, cation demineralizer room, and makeup and I
purification domineralizer room. Physical inspection is not possible due to I
radiological conditions at these locations.
Question 11 Since there are no QA/QC records available, provide any test data to justify the allowables used in the analysis. Also, identify the year 1 l
TER-C5506-263 (date of publication) of ACI 531 used in the analysis. Indicate and justify any higher stress allowables when compared to ACI 531-79.
If using any tests that are different from on-site tests, the Licensee i
should justify the applicability of those tests to the Crystal River Unit j
3 masonry structures.
Response 11 In this response, the Licensee indicated that no test data were available to support masonry allowable stresses. Allowable stresses were obtained from i-ACI 531-79, except allowable axial compression stress, which was obtained from t.
the Southern Standard Building Code. This value (70 psi) was considered more
'lj appropriate than the ACI limit because the walls at the Crystal River plant are partition walls, whereas the ACI limit of 120 psi (based on f'm = 700 psi)
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was derived for load bearing walls (see Response 16). The allowable flexural compression was obtained from ACI 531-79 and was based on an f'm of 1200 psi.
'7 This value (0.33 f'm) was 396 psi. However, even if the minimum f'm given in
'O Table 4.3 of ACI 531-79 (700 psi) were to be used, there would be no effect on the evaluation since mortar tension controls the adequacy of the walls.
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Allowable tension stresses were obtained from ACI 531-79 and were based on an m value of 750 psi for Type N mortar (from ASTM C-270 specifications). The o
q tension allowables were 33.7 psi for tension perpendicular to the bed joint L..
and 27.4 psi parallel to the bed joint.
r This response is satisfactory and in compliance with the SGEB criteria, u
O Question 12 d
Explain how earthquake motions in three directions are treated in the
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analysis.
Indicate whether walls are subject to in-plane loading.
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Response 12 In this response, the Licensee indicated that the Crystal River Un.'t 3 Final Safety Analysis Report specified a horizontal ground acceleration of 0.05 g for OBE and 0.10 g for SSE. The vertical acceleration was two-thira3 of the horizontal acceleration. The total effect of earthquake loads on masonry walls was found by adding the absolute values of the out-of-plane
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TER-C5506-263 horizontal and vertical respor. es.
This is consistent with the Crystal River Unit 3 Final Safety Analysis Report. Since the walls at this plant are not shear walls, it was not necessary to combine in-plane horizontal seismic loads simultaneously with the out-of-plane and vertical loads. The critical load in the analysis was found to be out-of-plane horizontal earthquake.
This response is adequate and satisfies the SGEB criteria.
Question 13
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Provide sample calculations to justify that stresses for in-plane r,
loatligs are less critical than for out-of-plane loadings.
J Response 13 9
Sample calculations were provided for wall 3 in the control complex.
D These calculations take into account SSE seismic loads in the out-of-plane Uf[
horizontal, vertical, and in-plane horizontal directions. The out-of-plane horizontal earthquake produced a flexural tension stress of 80.9 psi, whereas
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the maximum in-plane horizontal earthquake produced a flexural tension stress of 53.2 psi. The stcesses due to vertical acceleration were combined with the 9
dead weight and produced a maximum axial stress of 21.1 psi in compression.
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The ACI 531-79 allowable stress for tension normal to the bed joint was 13.7 P'
psi, and after the SGEB increase factor of 1.3 was applied to it, the allowable tensile stress became 17.81 psi. The allowable axial compressive 7
stress was 70 psi, from the Southern Standard Building Code (see Response 16).
It can be seen that the tensile stress due to the out-of-plane horizontal earthquake was critical.
It should be noted that wall 3 did not qualify under the SGEB acceptance criteria, but this failure was later found to have no adverse effect on safety-related equipment (see Respense 15).
This response is satisfactory and complies with the SGEB criteria.
Question 14 According to Section 1.2.3 of Reference 6, a portion of wall 1 has been removed to eliminate the wall's possible effect on safety-related equipment (see Figure 4, Reference 6).
Explain how this modification removes the safety concern of wall collapse on equipment near wall 1.
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TER-C5506-263 f
Response 14 In this response, the Licensee stated tha' the only safety-related equipment associated with this wall is the control complex ventilation system main supply air duct. The collapse of the wall could damage the vertical section of this duct. The Licensee plans to remove the portion of wall which could pose a safety concern if it fell. This planned action is judged to be atisfactory.
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Question 15 r)
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According to Reference 6, walls 2 and 3 exceed ACI 531-79 allowable stresses by 50% to 60%; however, according to the cover letter of Reference 6, a recent inspection has shown that the collapse of walls 2
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and 3 would not have an adverse effect on safety-related equipment in the "la area.
Indicate the recent findings that have permitted these walls to be considered differently than in the original evaluation (Reference 2) which presented walls 2 and 3 as safety-related. Also, provide the i
jff documentation of the evaluation of these walls that, according to the 1
1 cover letter of Reference 6, was due by April 30, 1984 but has not yet been provided.
Ji il-Response 15
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! t The Licensee indicated that the only safety-related items located in the vicinity of the walls were electrical conduits. These conduits are located at the boundary between the top of the masonry walls and the concrete floor system above. These conduits are not grouted into the walls or physically i
attached to the walls. The Licensee also stated some modifications were done
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to the walls to ensure that they were not physically in contact with the
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- conduits, b
i The Licensee also clarified that it did not intend to reevaluate these 4
walls, but only to draw up alternatives to determine the best controls to 1
1 assure that these walls will not adversely affect any safety-related items in l[
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the vicinity of the walls. These controls were documented in the April 30, 1984 letter (13]. Basically, they consist of changes in safety-related engineering procedures that assure that non-safety-related equipment will be 4
placed in the vicinity of these walls in the future.
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The Licensee's response is judged to be adequate and satisfactory.
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TER-C5506-263 Question 16 With respect to Section 3.1.1.4 of Reference 6, walls 1, 4, and 5 were not qualified using the ACI 531-79 formula for allowable axial compressive stress. These walls were qualified using the Southern Standard Building Code (SSBC) compression stress allowable of 70 psi.
Also, fixed side boundary conditions in walls 4 and 5 were relaxed.to allow for a redistribution of moment, which helped to keep stresses within allowable limits. Provide and justify the reasons for accepting these walls as meeting the SGEB criteria.
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Response 16 The Licensee indicated that the walls intersect other masonry walls with running bond at corners. The conditions at the intersecting edges do not 1
provide complete rigidity so that some moment redistribution will take place.
i However, as discussed in Response 4 above, even if the boundary is considered l{
to be hinged, the induced stresses are still within the ACI 531-79
!L allowables. The formulas for the theoretical buckling strength of the critical wall, using a factor of safety of 9, will result in an allowable
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compressive stress of about 90 psi at the base (maximum allowable by ACI 531-79 is 120 psi, based on f'm = 700 psi). Therefore, the allowable value of 7~
70 psi used in the analysis is acceptable.
The Licensee's response is adequate and satisfactory.
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Question 17
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With respect to the seismic analysis of the instrument room walls in the
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turbine building, Section 3.2 in Reference 6 indicates that the effect of the first mode of vibration was increased by 5% to account for high modes. Indicate why these walls were not checked with an eight mode L
analysis as were the five walls in the control complex.
Indicate whether there are other differences in the criteria between the control complex walls and the instrument room walls. Also, Figures 22 and 23 show " knife edge" boundary conditions for walls in the turbine building.
Indicate whether " knife edge" represents a pinned condition or whether some other alternate condition was assumed. The staff does not accept the use of arching or wedging action at boundary connections in qualifying masonry walls (the staff position is attached).
TER-C5506-263 Response 17
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The Licensee clarified that the instrument room walls were done in a separate analysis prior to the control complex wall analysis. The lowest frequency was about 36 cycles /second, which indicates a negligible contribution of higher modes.
The " knife-edge" condition represents a pinned condition.,The Licensee indicated that no alteration of the boundary condition is necessary (i.e., fix~
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base) because the maximum stress of these walls is only 23% of the ACI 531-79 allowable.
The Licensee's response is adequate and is consistent with the SGEB J
criteria.
t 3.2 EVALUATION OF LICENSEE'S APPROACH TO MODIFICATIONS 7
, jg; According to the Licensee's reevaluation of masonry walls at the Crystal River plant, walls 1, 2, and 3 in the control complex do not meet the SGEB
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acceptance criteria. The collapse of wall I could possibly damage the I{~
vertical section of the control complex ventilation system main air duct.
i 5, Therefore, the portion of this wall that could impact the duct was removed. A
,lm recent inspection of walls 2 and 3 showed that the only safety-related j
equipment near these walls are electrical conduits penetrating the walls at J
the top boundary. Slight modifications were performed to ensure that the conduitsarenotincontactwiththewalls;anycollapseofthhwalls, q
j therefore, would not result in damage to the conduits.
These were the only modifications to masonry walls required at this plant. The Licensee's approach to modifications has been reviewed and found adequate and in compliance with SGEB criteria.
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TER-C5506-263 4.
CONCLUSIONS A detailed study was performed to provide a technical evaluation of the masonry walls at Crystal River Unit 3.
Review of the Licensee's criteria.and I
additional information provided by the Licensee led to the conclusions given below.
The Licensee's criteria have been found technically adequate and in f
compliance with the SGEB criteria except for the following areas.
An allowable stress increase factor of 1.67 for extreme loading o
conditions was initially used in the evaluation. This is in excess 4jj of the SGEB factors for masonry shear and tension normal to the bed L
joint (1.3) and reinforcement shear and tension parallel to the bed 9
joint. However, the Licensee has since reevaluated all the walls 2,
using the SGEB factors. The following items are based on the updated l~
evaluation.
1 Wall 1 in the control complex will not withstand a safe shutdown
' g-o "JF earthquake. The collapse of this wall could damage part of the control complex ventilation system main supply air duct. This wall i[l has been rendered acceptable under IE Bulletin 80-11 by the removal l L, of the portion of the wall that would impact the duct in the event of a collapse.
f Walls 2 and 3 in the control complex do not meet the SGEB criteria o
with respect to allowable stress. However, as stated in Response 15 in Section 3.1, the only safety-related equipment located near these wsils are electrical conduits penetrating the walls at the top a
l-boundary. Any failure of the walls would result in the masonry blocks moving away from the conduits. Slight modifications were
]7 performed to ensure that walls are not physically in contact with the lj conduits.
It is concluded that no damage to existing safety-related equipment would result from the failure of walls 2 and 3.
3, o
Walls 4 and 5 in the control complex comply with the SGEB criteria l'-
with the following exception. The ACI 531-79 formula for allowable compressive stress was not used. Instead, a value of 70 psi was t
1' taken from the Southern Standard Building Code (SSBC). However, l
since the theoretical buckling strength, with a safety factor of 9, will give an allowable compressive stress of 90 psi (maximum f
allowable by ACI 531-79 is 120 psi, based on f'm = 700 psi). the value of 70 psi is considered acceptable.
1 t i E
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TER-C5506-263 7
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5.
REFERENCES 1.
IE Bulletin 80-11 Masonry Wall Design NRC, May 8, 1981 2.
R. M. Bright (Florida Power Corporation)
Letter to J. P. O'Reilly (NRC)
Subject:
Crystal River Unit 3 - Response to IE Bulletin 80-11, Ite'ms 1, 2a, and 3 - Masonry Wall Design July 7, 1980 3.
R. M. Bright (Florida Power Corporation)
Letter to J. P. O'Reilly (NRC) m
Subject:
Crystal River Unit 3 - Extension of kesponse Deadline to Reference 1,' Item 2b
/.
7 November 7, 1980 4.
P. Y. Bay $ard (Florifta Power Corporation)
~
Letter tc.1. P..p'Reilly (NRC)
"f
Subject:
Crystal River. Unit 3 - Response to Reference 1, Item 2b L
November 17, 1980 h
5.
D. G. Mardis (Florida Power Corporation) 1..
Letter to J. P. O'Reilly (NRC)
Subject:
Crystal River Unit 3 - Amendment to Reference 2 March 23, 1982 g
6.
G. R. Westafer Letter with Attachments to J. F. Stolz (NRC).
-]
Subject:
IE Bulletin 80-11, Masonry Wall Design Request for Additional J
Information Florida Power Corporation, G
February 29, 1984 d
7.
G. R. Westafer Letter with Attachments to J. F. Stolz (NRC)
Subject:
7E Bulletin 80-11, Masonry Wall Design Request for Additional Information Florida Power Corporation, November 25, 1985 8.
Recomended Guidelines for the Reassessment of Safety-Related Concrete Masonry Walls, Prepared by Owners and Engineering Firms Informal Group on Concrete Masonry Walls October 6, 1980 9.
J. J. Ler.anan (NRC)
Inspection at Crystal River Site near Crystal River, Florida Inspection Date: September 29 to October 1, 1980 NRC Report No. 50-302/80-36 November 7, 1980 _
TER-C5506-263 10.
SGEB Criteria for Safety-Related Masonry Wall Evaluation Developed by the Structural and Geotechnical Branch of the NRC, July 1981 11.
Uniform Building Code International Conference of Building Offic: tis, 1979 12.
Building Code Requirements for Concrete Masonry Structures Detroit: American Concrete Institute, 1979 ACI 531-79 and ACI 531-R-79 13.
G. R. Westafer l,
Letter to J. F. Stoly (NRC)
Subject:
IE Bulletin 80-11, Masonry Wall Design Request for Additional Information Florida Power Corporation, j
April 30, 1984 i
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APPENDIX A e
SGEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION (DEVELOPED BY THE STRUCTURAL AND GEOTECHNICAL ENGINEERING BRANCH
[SGEB] OF THE NRC) l m
f kr y
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S L.
FRANKLIN RESEARCH CENTER DIVI 9ON OF ARVIN/CALSPAN 20th & RACE STREET 5. PHILADELPHIA,PA 19103
TER-C5506-263 CONTENTS Section Title Page A-1 1
GENERAL REQUIREMENTS 2
LOADS AND LOAD COMBINATIONS.
A-1 1
a.
Service Load Combinations A-1 b.
Extreme Environmental, Abnormal, Abnormal / Severe j
Environmental, and Abnormal / Extreme Environmental Conditions.
A-2
)
A-2 3
ALLOWABLE STRESSES.
a 4
DESIGN AND ANALYSIS CONSIDERATIONS.
A-3 5
REFERENCES.
A-4
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seu M
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1
TER-C5506-263 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, d
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.
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2.
Loads and Load Combinations The loads and load combinations shall include consideration of normal
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g-
_F 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 combinations shall apply (for definition of load terms, see SRP Section 3.8.4II-3).
~
m (a) Service Load Conditions (1) D+L (2) D+L+E (3) D + L + W iJ If thermal stresses due to T and R are present, they should be o
o included in the above combinations as follows:
L.
(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'.
A-1
~.
TER-C5506-263 (b) Extreme Environmental, Abnormal, Abnormal / Severe Environmental, and Abnormal / Extreme Environmental Conditions (4) D + L + To+Ro+E (5) D+L+To+Ro+Wt (6) D + L + Ta+Ra + 1.5 P,
+ 1.25 E (7) D + L + Ta+Ra + 1.25 Pa + 1.0 (Yr + Yj + Y )
m
+ 1.0 E' f~
(8) D + L + Ta+Ra + 1.0 Pa + 1.0 (Yr + Yj + Y )
m In combinations (6), (7), and (8) the maximum values of P, T -
a a
R
- Yj', Y, and Y,' including an appropriate dynamic load a
r m
factor should be used unless a time-history analysis is performed to I
justify otherwise. Combinations (5), (7), and (8) and the corresponding structural acceptance criteria should be satisfied 3
l first without the tornado missile load in (5) and without Y
- Yje r
and Y in (7) and (8).
When considering these loads, local sectior.
m l
strength capacities may be exceeded under these concentrated. loads, g-provided there will be no loss of function of any safety-related
- F system.
Both cases of L having its full value or being completely absent j
should be checked.
1 3.
Allowable Stresses Allowable stresses provided in ACI-531-79, as supplemented by the a
following modifications / exceptions, shall apply.
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(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.
'u (c) When tension perpendicular to bed joints is used in qualifying the unreinforced masonry walls, the allowable value will be justified by test ' program or other means pertinent to the plant and loading conditions.
For reinforced masonry walls, all the tensile stresses will be resisted by reinforcement.
(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 table:
A-2
, + - - -
,,,,-ma
--em----,-,e-
-e
-mv-,,
w
+ - -,
er-,
y s-e
-y-,-w y-m--*,*4-r---ar
-e
,,1-
-v'r-
e pw--=y weg
TER-C5506-263 Type of Stress Factor Axial or Flexural 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 Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular j
to bed joint for reinforced masonry 0
4 2
1.3 for unreinforced masonry g-Notes F
a (1) When anchor bolts are used, design should prevent facial 7
spalling of masonry unit.
1
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(2) See 3(c).
4.
Design and Analysis Considerations (a) The analysis should follow established principles of engineering
~
mechanics and take into account sound engineering practices.
Assumptions and modeling techniques used shall give proper (b) 7 considerations to boundary conditions, cracking of sections, if any, j
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 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.
A-3
TER-C5506-263 (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 acceptance.
(j) Licensees or applicants shall submit QA/QC information, if available, for staff's review.
1.
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).
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(k) For masonry walls requiring protection from spalling and scabbing due to accident pipe reaction (Y ), jet impingement (Y ), and missile r
impact (Y ), the requiremer.ts similar to those of SRP 3.5.3 shall m
'I apply. However, actual review will be conducted on a case-by-case
' a.f basis.
3 5.
References i
(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
~
l_
Buildings - Applied Technology Council ATC 3-06.
(d) Specification for the Design and Construction of Load-Bearing 3
,j Concrete Masonry - NCMA August, 1979.
(e) Trojan Nuclear Plant Concrete Masonry Design Criteria Safety
.I Evaluation Report Supplement - November, 1980.
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i A-4
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--w-,
ew--s
,m,-.--.,-e--
., or,.,
.-r.
.--%.-,,,,e, s w r.,
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