ML20079K176

Masonry Wall Design,Tmi Unit 1, Technical Evaluation Rept

ML20079K176
Person / Time
Site:	Three Mile Island
Issue date:	12/23/1982
From:	Con V FRANKLIN INSTITUTE
To:	Nilesh Chokshi NRC
Shared Package
ML20079K181	List: ML20079K176
References
CON-NRC-03-81-130, CON-NRC-3-81-130 TAC-42919, TER-C5506-159, NUDOCS 8212290141
Download: ML20079K176 (33)

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TECHNICAL EVALUATION REPORT MASONRY WALL DESIGN METROPOLITAN EDISON COMPANY THREE MILE ISLAND UNIT 1 NRC DOCKET NO. 50-289 FRC PROJECT C5506 NRCTACNO. 42919 FRC ASSIGNMENT 6 NRC CONTRACT NO. NRC-03-81 130 FRC TASK 159 Prepared by Franklin Research Center A'uthor: V. N. Con 20th and Race Street Philadelphia, PA 19103 FRC Group Leader: V. N. Con Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer: N. Chokshi December 23, 1982

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With slight modification by NRC staff 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

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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 represent.* that its use by such third party would not intringe privately owned rights.

Prepared by: Reviewed by: Approved by:

N NM bM / wth / _8[ CW Principal Author Department %Irectof Date: CO Date: /2 - 2 % 2 L- 12-Z3-?E Date:

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CONTENTS Section Title Pm 1 INTRODUCTION . . . . . . . . . . . . . 1 1.1 Purpose of Review . . . . . . . . . . . 1 1.2 Generic Issue Background . . . . . . . . . 1 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 . . . . . . . . . . . . 14 4 CONCLUSIONS. . . . . . . . .. . . . . . 16 5 REFERENCES . . . . . . . . . . . . . . 17 APPENDIX A - SEB CRITERIA FOR SAFETY-RELATED NASONRY WALL EVALUATION (DEVEIDPED BY THE STRUCTURAL ENGINEERING BRANCH (SES) OF THE NRC)

APPENDIX B - NRC REQUEST FOR ADDITIONAL INFORMATION APPENDIX C - DRAWING OF WALL RB-1 IN THE REACTOR BUILDING t

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. FOREWORD This 'Mchnical 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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1. INTRODUCTION '

l.1 PURPOSE OF REVIEW The purpose of this review is to provide a technical evaluation of the Licensee response to IE Bulletin 80-11 (1) with respect to compliance with the Nuclear . Regulatory Commission (NRC) maconry wall criteria. In addition, if the Licensee plans repair work on masonry walls, the planned methods, procedures, and repair schedules are reviewed for acceptability.

1.2 GENERIC ISSUE BACKGROUND In the courae of conducting inspections at the Trojan Nuclear Plant, Portland General Electric Company (PGE) 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 inadequate 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 wers 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 BACKGROUND In response to IE Bulletin 80-11, Metropolitan Edison Company provided the NRC with documents concerning the design of masonry walls [2, 3, 4, 5].

Based on the information supplied by the Licensee, a review of the status of masonry walls at Three Mile Island Unit 1 was conducted. As a result of the review, a request for additional information was sent to the Licensee on January 22, 1982 (Appendix B). The Licensee responded to this request on April 15, 1982 [6] and September 20, 1982 [7].

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According to Reference 7, a total of 15 walls have been identified as safety-related walls. Thirteen walls are in the auxiliary building, one wall l

l is in the reactor building, and one wall is in the turbine building. The

( materials used in the construction were specified as follows [2]:

Hollow concrete blocks AS M C-90 Grade N Solid concrete blocks ASTM C-145 Grade N Mortar ASM C-270 Type N Horizontal joint reinforcement Dur-O-Wall No. 9 Rod Bar reinforcement ASM A-615-68 Grade 40 f 000 Franklin Research Center a % orn.Fr.nenin

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2. EVALUATION CRITERIA The basic documents used for guidance in this review were the criteria developed by the Structural Engineering Branch (SEB) of the NRC [8] (attached as Appendix A to this report), the Uniform Building Code (9), and ACI 531-79 t10 ] .

In general, the materials, testing, analysis, design, construction, and inspection of safety-related concrete masonry walls should conform to the SEB criteria [8]. Pbr operating plants, the loads and load combinations for qualifying the masonry walls should conform to the appropriate specifications in the FSAR for the plant. Allowable stresses are specified in Reference 10 and the appropriate increase factors for abnormal and extreme environmental loads are given in Reference 8.

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3. TECHNICAL EVALUATION l

l This evaluation is based on the Licensee's earlier responses [2, 3) and subsequent responses (6, 7] to the request for additional information (Appendix B). The Licensee's criteria [2] were evaluated with regard to design and analysis methods, loads and load combinations, allowable stresses, construction specifications, materials, and relevant test data. We Licensee's response to the questions contained in the request for additional' information was also reviewed. I 3.1 EVALUATION OF LICENSEE'hi CRITERIA The Licensee has performed the reevaluation of the masonry walls using the following criteria [2):

l o Allowable stresses closely follow the recommendations given in ACI 531-79 [10).

o Loads and load combinations are in accordance with the plant Final Safety Analysis Report (FSAR) .

o he working stress design method was used in the analysis.

o Damping values are as follows:

Unreinforced walls 24 - Operating basis earthquake (OBE) 44 - Safe shutdown carthquake (SSE)

Reinforced walls 44 - OBE 76 - Asg The Licensee responded to all questions in the request for additional information (Appendix B). These responses are reviewed below.

Response 1 With respect to the multi-mode effect, the Licensee used the spectral acceleration at the fundamental frequency of the wall and applied a factor of 1.05 to obtain a uniform static load to perform the analysis. In order to justify this method, the Licensee provided results of the analysis using the

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multi-mode response spectrum method for three walls; the results demonstrated that the Licensee's method produced results in close agreement with the

, multi-mode response spectrum method. The maximum difference between the two methods is approximately 10%. Based on these results, it is concluded that the Licensee's method is adequate.

Response 2 In response to this request, the Licensee stated that Kasonry walls at the Three Mile Island Nuclear Station Unit 1 are all interior walls and not subjected to wind loads. The Licensee also indicated that no significant temperature differential existed across any of the walls. Therefore, thermal i o

effects were not included in the analysis. %e Licensee's response has '

resolved the concern of this request.

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Response 3 The Licensee's response indicates that, although the reevaluation criteria stated that multi-wythe walls were analyzed as single-wythe walls,

' I this option was not exercised. In fact, as part of the modification program, all collar joints of multi-wythe walls were filled with a non-shrink grout called Five Star Grout No.100 from the U.S. Grout Corporation. Further discussion of the collar joint is given in Response 14.

The Licensee's response is considered to resolve this question.

Response 4 With respect to the equipment loads, the Licensee indicated that the forces generated by the attached equipment were obtained by multiplying the equipment masses by 1.05 times the peak acceleration of the floor response spectrum above the wall. He Licensee stated that the walls and the equipment attached to them are practically rigid. He lowest fundamental frequency of all of the walls was 24 Hz, which is in the zero period acceleration (ZPA) range. As such, the use of the peak floor response spectra in evaluating the equipment load is considered conservative. It was pointed out that the 4

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TER-C5506-159 majority of the equipment attached to the wall is rigid; the ratio of peak spectral acceleration to the zPA varies from 3 to 5.

It is recognized that the peak spectral acceleration would produce a i higher estimate of the loads as compared to the ZPA of rigid walls. Thus, the i

factor of 1.05 used by the Licensee is appropriate.

Response 5  !

The procedure used to incorporate the effects of vertical acceleration

was as follous

j 1. Masonry walls are rigid in the vertical plane (frequency greater than

) 40 Hz) . Vertical acceleration was taken as the vertical zero period i

acceleration (ZPA) at the appropriate floor level.

2. Dead load of the wall was obtained by multiplying the mass of the  !

wall by the acceleration of gravity minus the vertical ZPA acceleration of the floor above the wall.

3. The above dead load was used together with the stresses resulting from out-of-plane loads to evaluate the tension stresses normal to 4

the bed joint. -

Therefore, the effects of. the vertical acceleration were included in the analysis. This response is satisfactory.

Response 6 With respect to the effects of interstory drif t, the Licansee provided the following informations o In-plane effects of interstory drif t The calculated interstory drif t effect of the auxiliary building and the reactor building is small compared to the values given in the i Licensee's criteria. For further discussion of the Licensee's allowable strains, one is referred to Response 8. . For the auxiliary building, the drif t of the floor level where the walls are located is 0.00006 in/in (OBE) compared to the allowable of 0.0001 in/in and 0.000132 in/in (SSE) compared to that of 0.000167 in/in. For the reactor building, the drif t is 0.000076 in/in !OBE) and 0.000152 in/in (SSE) .

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TER-C550 6-159 o Out-of-plane effects of interstory drif t The License has calculted the additional stress resulting from the l out-of-plane drif t effects for all the affected walls and found that I

the stresses caused by the interstory drift range from the smallest values of 6.5 psi (OBE) and 12.9 psi (SSE) for wall AB-7 to the largest values of 15.4 psi (OBE) and 30.9 psi (SSE) for wall AB-5, while the Licensee's allowable stresses are 27.4 psi (OBE) and 45.7 I

' psi (SSE). When stresses from all loads were combined, there was no I { case in which the calculated stress exceeded the above allowables.

I Further discussion of the Licensee's allowable stresses can be found in Response 17.

, The piping loads are calculated by one of the following procedures

1. Whenever available, pipe reaction loads from the pipe stress analyses

! were incorporated into the analysis.

2. The seismic loads from the pipes were obtained by multiplying the mass of the pipe by 1.05 times the peak of response spectrum corresponding to the floor above the wall. A review of the plant FSAR indicated that, for piping systems anchored to the walls, no amplification due to the floors is assumed. As such, the Licensee's approach is considered sat.isfactory.

Responses 7 and 13 The Licensee's response indicated that, in order to account for

! uncertainties existing in masonry walls with respect to variations in mass, modulus of elasticity, and material properties, the design criteria require i the modulus of elasticity of 1000 f,' be varied by an amount of plus or

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2 If the fundamental frequency of the wall based on 1000 f,' is on the high frequency side of the amplified region of the floor. response spectrum,

, then 800 f,' is used ' to obtain the fundamental frequency of the wall. On the other hand, if the fundamental frequency of the wall using an E of 1000 f,' is on the low frequency side of the amplified region, then an E value of 1200 f,' is used to obtain the fundamental frequency of the wall.

However, for Three Mile Island Unit 1, a value of 800 was used in all cases since f,'

l the fundamental frequency of walls was on the high frequency side of the amplified region of .the response spectrum.

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l The Licensee's response to Requesta 7 and 13 is considered adequate and l satisfactory.

Response 8 According to this request, the Licensee is to provide a complete derivation of an expression used to relate the strength of the strut to a strain at cracking and explain how this expression relates to the permissible strain levels of unconfined and confined walls. However, in its response, the

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I.icensee stated that this expression was no longer used to develop the recommended values for permissible strain.

In fact, the Licensee relied on the works published by Fishburn and Becica, cited in Reference 2, to obtain the allowable strain of 0.0001 (OBE) for unconfined walls and applied an increase factor of 1.67 to obtain the allowable strain for the factored load cases. For confined walls, the works done by Mayes et al., cited in Reference 2, were used to obtain a value of 0.0008 (OBE). The applicability of Mayes' tests to the walls at the plant will be discussed in Responses 11 and 15.

The Licensee's allowable strains are reasonably small, and since there is very limited amount of available test data, these values can be considered appropriate.

Response 9 In dais response, the Licensee indicated that, in order to evaluate the out-of-plane response of the walls, the boundary conditions were considered as follows:

a. Fcr walls with two vertical boundaries, all sides were assumed to be i simply supported except the top was free.

b. For walls with one vertical boundary, the walls were assumed to be fixed at the bottom and free on the other three sides.

c. Fbr horizontally spanned walls, the top and bottom were assumed to be free and the other two sides simply supported.

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f It is noted that along the vertical boundary, in most cases, besides the j mortar joint, one wythe of the masonry wall has the end block embedded in the intersecting concrete structures. This embedded portion, sometimes referred 1 to as a key, is usually 2 in by 8 in. This configuration can be modeled as a t

j simply supported boundary. Regarding walls having one single vertical ,

! boundary, the assumption of freestanding cantilever should result in a more 1

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conservative estimate.

The Licensee's response is considered adequate.

4 Response 10 j

The Licensee stated that the originally proposed use of the steel brackets to reinforce the end spans of the north and south walls of the f

elevator shaft has been abandoned. Instead, a decision has been made to provide supports at the free end to reduce the bending moments resulting from 4

the dynamic response of the walls. Further discussion on this method of l

modification will be presented in Section 3.2.

The out-of-plane drift problem associated w.th the steel brackets does not exist anymore. Hence, the concern has been resolved satisfactorily.

• Responses 11 and 15 In response to Requests 11 and 15, the Licensee used the results from a i test program being performed at the Earthquake Engineering Research Center, University of California, Berkeley, to evaluate the in-plane shear strength and strain of masonry piers.

Regarding the applicability of these tests to the masonry walls in the ,

plant, the following information was presented:

a. Ioading j

Although a seismic time history was not applied to the test walls, cyclic loading used in these tests should be appropriate to study the structural performance of the walla subject to a reversed load type.

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b. Size of Test Walls Due to the limited capacity of the actuator at Berkeley, the tested piers have the following sizes: for the height-to-width ratio of 1 0.5, the pier is 3 f t 4 in high and 6 f t 8 in long. For the {

l height-to-width ratio of 1, the pier is 4 f t 8 in high and 4 f t 8 in i long. Por height-to-width ratio of 2, the pier is 5 f t 4 in high and l 2 ft 8 in long. Even though the tested walls are smaller than the l actual walls in the plant, their aspects ratios are similar to those

'at the plant.

c. Boundary Conditions The boundary conditions of the tested walls were set up so that the 4

moment fixity occurred at the top and bottom of the piers and the vertical edges are free. The walls in the plant are either fixed at the bottom and free at the othe sides or simply supported at the bottom and two vertical edges and free at the top. It is believed that, if the walls at the plant are confined either on three or four sides or at the top and bottom, then they would behave in the same way as the tested walls,

d. Material Strengths The compressive strength used for the walls at the plant was 900 to 950 psi, whereas prism strength of the tested piers ranged from 1350 pai to 3500 pai. However, it is believed that the actual in situ f'm of the walls would be higher than the assumed compressive a treng th.

e. Reinforcement The piers at Berkeley are reinforced, whereas most of the walls at the plant are not. Again, it is believed that if the walls at the plant are confined on three or four sides or at the top and bottom, then cracks in the unreinforced walls would occur at the same strain levels as in the tested walls. ,

Though the above information indicates that there are some differences between the walls at the plant and the tested walls, it is judged that the test data would provide useful information to evaluate the performance of the walls in question. In addition, there is a very limited amount of test data which can be used to study the types of walls and the loading and boundary conditions found at the plant. -

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TER-C5506-159 Results of the Berkeley tests are given belows o Stress Results A statistical analysis of data from 33 tests showed that, for the case in which the population mean strength is taken at the center of the 954 confidence interval, the Licensee's allowable shear stress (for the OBE case, ACI 531-79 is used; for the SSE case, an increase factor of 1.67 is used) will exesed the test values 108 times in 1,000,000

'(0.01%) for OBE events and 1926 times in 1,000,000 (0.194) for SSE events. Furthermore, the factor of safety (SF) associated with the Licensee's allowable shear stresses for the case of masonry taking shear ist SF varies between 2.02 and 3.12 for OBE and between 1.5 and 1.96 for SSE. For the case of reinforcement taking shear, SF varies between 1.91 and 3.27 for OBE and between 1.28 and 1.96 for SSE.

The test results demonstrated that a significant margin of safety associated with the Licensee's allowable exists in both the OBE and SSE cases. Even though the Licensee relied on an increase factor higher than the SEB's factor (1.67 vs 1.3 for masonry taking shear), a review of the calculated shear stress of all walla demonstrated that if a factor of 1.3 is used, these walls can still be qualified.

o Strain Results If the population mean is taken at the center of the 954 confidence interval, the factor of safety associated with the Licensee's

• allowable strain varies between 2.15 and 2.90 and between 2.13 and  :

2.61) respectively, for OBE and SSE events.

Again, the test results demonstrated that a significant margin of safety associated with the Licensee's allowables exists in both the OBE and SSE cases. Response 8 provided more discussion concerning this subject.

Based on the Licensee's response, it is concluded that the concern has been resolved.

Response 12 The Licensee's response indicated that neither the energy balance technique nor the arching theory was used in the analysis. This response has resolved the concern.

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Response 13 4

This response has been discussed previously in Response 7.

Response 14 With respect to the collar joint strength, the Licensee provided the technical data for the non-shrink Portland Cement Grout to be filled in the

collar joints; the grout used was Five Star Grout No.100 from U.S. Grout 1

Corporation, which has a specified compressive strength of 500 pai af ter 7 days.

Furthermore, the shear and tensile strength of the repaired collar joints

were tested by taking core samples from the walls. The shear strength was determined by applying a load across 3 inches of the free end of the core sample until failure. The tensile strength was performed in accordance with ASTM C-496 " Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens". 'Iwst results showed that the average shear strength of seven test specimens was 192 psi with a coefficient of variation equal to 6.44, and the average tensile strength was 182 psi with a coefficient of i

variation equal to 6.94. These values are much higher than the criteria allowables of 12 psi.

This response is considered satisfactory.

Response 15 ,

I This response has been discussed in Response 11.

Response 16

! The Licensee's response indicated that the in-plane shear stresses generated in the walls are very small compared to the allowable. The Licensee conducted a study of all the walls; the results demonstrated that if the SEB increase factor of 1.3 for the load cases involving the SSE event was used (instead of the proposed factor of 1.5), the calculated in-plane shear stresses are still very small compared to the allowable. In fact, the highest i

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I i value of in-plane shear stress is only 8.1% of the SEB-suggested allowable stress for factored loads. Werefore, the SEB increase factor of 1.3 is 4

adopted for Three Mile Island Unit 1.

Because the Licensee finally adopted the SEB increase factor, this response is ratisfactory.

Response 17

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With respect to the allowable tension normal to bed joint, the Licensee relied on the ACI 531-79 Code for the OBE loading case; for the SSE case, however, an increase factor of 1.67 was applied for the allowable stress, whereas the SEB criteria allow only 1.3. To justify this increase factor, the Licensee cited tests done by the National Concrete and Masonry Association (NCMA). The Licensee recognizes that there are very limited data available for tension capacity of masonry normal to bed joint. In all, only six unreinforced test specimens (multi-wythe, type S mortar) were tested. A I

statistical analysis of these test results indicated that the safety factor associated with the Licensee's allowables for an OBE event varies between 2.38 and 3.32, and the safety factor range for a SSE event varies between 1.42 and 1.99. However, a review of the resulting stresses provided by the Licensee illustrated that if the SEB increase factor is used, only one wall needs a j factor of 1.56 to be qualified.

Although the increase factor used by the Licensee did not meet the the SEB criteria, low damping levels were used in the analysis (24 for OBE and 44 for SSE) . Therefore, it is cocluded that the intent of the SEB critera '

has been met.

• Response 18 g The Licensee's response indicated that the specified increase factor of 1.33 for reinforcement bond for factored loads is in accordance with the 1979 Uniform Bdilding Code, Section 2303 [9] . Although the SEB does not specify this particular factor, it refers to Uniform Building Code-1979 for the design

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i TER-C5506-159 i requirements other than those specified in the SEB criteria. This response is satisfactory.

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Response 19 i > i' The Licensee stated that a recent visual survey revealed that wall AB-14

is a reinforced concrete wall, not a block wall, and therefore it is not in the scope of IE Bulletin 80-11 [1] . This response is satisfactory, f

Response 20 1 1

, The Licensee indicated that all proposed modifications were completed as i

of February 9, 1982. Further details of wall modifications can be seen in the

! next section.

! 3.2 EVALUATION OF LICENSEE'S APPROACH TO WALL MODIFICATIONS i .

For the composite walls in the auxiliary building, the Licensee used non-shrink Portlend Cement Grout to fill the collar joint. In Response 14 I

4 (Section 3.1), the Licensee provided the technical data for this particular I

grout.

j For the wall in the reactor building, the Licensee decided to install steel channels attached to the existing U-frames to support the free end of

! the north and south walls to sufficiently reduce the bending moments. In j addition, a horizontal steel frame would be installed on the west side wall to

reduce its span. It should be noted that this wall forms an elevator shaf t ,

I and has a U-shaped configuration. The north side and south side walls are 100 f t 11 in high by 8 f t 7 in longs each wall has two columns running along its height which are separated by about 4 ft. The west side wall is also 100 f t 11 in high by 11 ft long; it is vertically reinforced and has lateral restraints at four different elevations. The drawing in Appendix C illus-trates the above description. -

For the wall in the turbine building, all visible cracks have been -

repaired, and physical expansion joints have been installed between the block I nklin Research Center A Dhessen of The Pensen inmunuse

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l TER-C550 6-159 walls and the steel beams penetrating through the wall. All modifications were completed as of February 9, 1982. The Licensee's approach to wall modifications is considered satisfactory pending the following confirmatory action: Since the wall in the reactor building is very high (100 f t) and the calculated stresses- significantly exceed the allowables, the Licensee is requested to perform a reanalysis relying on the su criteria to confirm the structural integrity of this wall.

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4. COICLUSIONS r

A detail $d study was performed to provide a technical evaluation of the masonry walls at Three Mile Island Unit 1.

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

The criteria used for reevaluation of the mascary walls, along with the '

additional information provided by the Licensee, indica'te that 'tne Licensee's criteria are in compliance with the SEB criteria [8] . .

With reference to Responses 10 and 14 (Section 3.1) , 'the Licensee's approach to wall modifications is judged to be adequate if the following condition is mets a reanalysis of the wall in the reactor building should be performed to ensure that the modified wall will satisfy the SEB criteria.

Further information about this wall can be seen in Section 3.2.

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5. REFERENCES s

1. IE Bulletin 80-11

" Masonry Wall Design" NRC, May 8, 1980

2. H. D. Hukill (Dir?ctor, TMI Unit 1, Metropolitan Edison Company)

Letter with enclosures to B. H. Grier (NRC).

Subject:

Three Mile Island Nuclear Station Unit 1 - IE Bulletin 80-11 November 17, 1980

3. Metropolitan Edison Company "Three Mile Island Unit 1 - Reevaluation of Safety-related Concrete Masonry Walls, NRC IE Bulletin 80-11"

. Topical Report No. 001, Rev. O July 14, 1981

4. J. G. Herbein (Vice President, TMI Unit 1, Metropolitan Edison f Company) 3 Letter with attachments to B. H. Grier (NRC) ,

Subject:

Three Mile Island Neclear Station Unit 1 - IE Bulletin 80-11 July 11,1980 1

5.

H. D. Hukill (Director, TMI Unit 1, Metropolitan Edison Company)

Letter with enclosures to B. H. Grier (NRC)

Subject:

x August 31, Three 1980 Mile Island Nuclear Station Unit 1 - IE Bulletin 80-11

6. H. D. Hukill (Director, TMI Unit 1, Metropolitan Edison Company)

, Letter to R. C. Haynes (NRC) .

Subject:

Three Mile Island Nuclear Station Unit 1 - IE Bulletin 80-11 t April 15, 1982 7.

H. D. Hukill (Director, TMI Unit 1, Metropolitan Edison Company)

Letter with Attachment to John F. Stolz (NRC) .

Subject:

Three Mile Island Nuclear Station Unit 1 - IE Bulletin 80-11 September 20, 1982 l

8. SEB Criteria for Safety-Related Masonry Wall Evaluation l Structural Engineering Branch of the NRC July 1981

9. Uniform Building Code International Conference of Building Officials,1979 l

l 10. ACI 531-79 and Commentary ACI 531-R-79

" Building Code Requirements for Concrete Masonry Structures" American Concrete Institute, 1979 I

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l APPENDIX A SEB CRITERIA FOR SAFETY-RELATED MASONRY WALL EVALUATION k (DEVELOPED BY THE STRUCTURAL ENGINEERING BRAEH (SEB) OF THE NRC) l an

. O.Franklin Research Center A Division of The Franklin Institute The Benen Frankhn Parkway, PNia.. Pa.19I03 (2IS) 448.ItX)O

. e TER-C550 6-159 CONTENTS Se ction Title Page 1 GENERAL REQUIREMENTS . . . . . . . . . . . A-1 2 TDADS AND IDAD COMBINATIONS. . . . . . . . . . A-1

a. Service Load Combinations . . . . . . . . . A-1

b. Extreme Environmental, Abnormal, Abnormal / Severe.

Environmental, and Abnormal / Extreme Environmental Conditions . . . . . . . . . . . . . A-2 l l

3 ALIDWABLE STRESSES . . . . . . . . . . . . A-2 4 DESIGN AND ANALYSIS CONSIDERATIONS . . . . . ., . . A-3 5 REFERENCES . . . . . . . . . . . . . . A-4 iii bll ~.

Frankhn,m Rese ar.ch Center

TER-C550 6-159

1. General Requirements )

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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 standard's 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 i

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

I 2. IoadEandIoadCombinations The loads and load combinations shall include consideration 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 combinations shall apply (for definition of load terms, see SRP Section 3.8.4II-3) .

Service Icad Conditions (a) -

(1) D+L (2) D+L+E (3) D + L + W If thermal stresses due to Toand R oare present, they should be -

included in the above combinations as follows:

1 (la) D+L+To+Ro I

(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-C5506-159 (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+L4 Ta+Ra + 1.5 Pa (7) D+L+Ta+Ra + 1.25 P, + 1.0 (Yr + Yj + Y m) + 1.25 E (8) D+L+Ta+Ra + 1.0 Pa + 1.0 (Yr + Yj + Ym) + 1.0 E' In combinations (6), (7) , and (8) the maximum values of P a, T a' Ra , Yj, Yr, and Ym, including an appropriate dynamic load 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 Yr , Yj, and Y a in (7) and (8). When considereing these loads, local.

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 test program or other means pertinent to the plant and loading conditions.- Fcr reinforced masonry walls, all the tensile stressed 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 i

nklin Research Center A Cheesen of The Frenten insuouse

e o TER-C550 6-159 Type of Stress Factor Axial or Flexural Compression 2.5 Bearing 2.5 Reinforcement stress except shear 2.0 but not to exceed Oa9 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 for unreinforced masonry 2 1,3 Notes (1) When ancbor bolts are used, design should prevent facial spalling of masonry unit.

(2) See 3 (c) .g

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 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 drif t effects should be considered.

nklin Research Center A Osamen af The Freneen Insensee

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TER-C5506-159 (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 chall 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.

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) .

(k) For masonry walls requiring protection from spalling and scabbing due to accident pipe reaction (Y r), jet impilngement (Y3 ), and missile impact (Ym ), the requirements similar to those of SRP 3.5.3 shall apply. However,'2ctual review will be conducted on a case-by-case basis.

5. Re ferences (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 Develcpment of Seismic Regulations for Buildinc;s - Applied Technology Council ATC 3-06.

(d) Specification for the Design and Construction of Load-Bearing Concrete Masonry - NCMA August, 1979.

l (e) Trojan Nuclear Plant Concrete Masonry Design Criteria Safety l' Evaluation Report Supplement - November,1980.

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APPENDIX B REQUEST FOR ADDITIONAL INNRMATION 1

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_1 Franklin Research Center A Division of The Franklin Institute The Senierrun FrankEn Perhey, PNia.. Pa. I9103 (213) 448. t000 i

TER-C5506-159 To facilitate completion of the review on this topic for TMI Unit 1, the Licensee should address the following:

i 1. The Licensee used a static analysis based on multiplying the mass of the structure by the peak uplified response spectra ( ARS) instead of a dynamic seismic analysis. To account for possible multi-mode effects, an amplification factor of 1.05 was used to obtain the equivalent static load. The Standard Review Plan (SRP) [9] accepts an equivalent static load method if the system is shown to be realistically represented by a simple model and the method gives conservative results. Furthermore, it suggests that a factor of 1.5 be applied to the peak ARS of the applicable floor response spec tra. In view of this, it is suggested that the Licensee provide

information to justify use of an amplification factor of 1.05.

2. Appendix 7.2 of Reference 3 provided a summary'of stresses, in which load combination included dead load, pipe reactions, and seismic loads. The thermal effect and wind load were not accounted for, In i Reference 2, the Licensee indicated that the thermal effect is

) insignificant, but did not justify this conclusion. The Licensee should elaborate on this point and also indicate if wind load was i included in the analysis.

3. In Reference 2, the Licensee used the single wythe as sumption (for out-of-plane loading) for multiple wythe walls. The Licensee should demonstrate that this assumption will result in a conservative evaluation.

4. With regard to stresses resulting from equipment, a static analysis was used by multiplying the weight of the equipment by. the peak acceleration of the response spectrum of the corresponding floor.

, The Licensee should clarify whether a multiplication factor was used to cbtain the equivalent static load or, if not, explain why.

5. With regard to the seismic analysis, the Licensee indicated thas the vertical component of the motion was not included in the analysis because the positive effect of the dead load on bed joint stresses was not included in the evaluation criteria. Although the positive effect is not easily determined, it is suggested that tz.e Licensee attempt to identify this positive effect (from test data or literature) and include it in the analysis or neglect it altogether, which will result in a conservative evaluation. However, it does not seen justifiable to neglect the vertical component of the motion.

6. The Licensee should describe how the interaMcy drif t (both in-plane l and out-of-plane) during a ' seismic event and U.e loads from piping l and/or equipment attached to the masonry walls were accounted for.

l Both the local and global effects of piping and/or equipment

attached to the masonry walls should be described and examples of the analysis provided.

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TER-C5506-159

7. In Section 6.1.2 of Enclosure 3 [2], ranges of + 25% and + 20% were given for the modulus of elasticity of ungrouted and grouted walls, respectively, to account for uncertainties in evaluating the frequency of the walls.

The Licensee stated, "if the frequency of the walls falls on the low frequency side of the amplified region of l the response spectrum adequate provisions are included to ensure t that the determination of the stress in the wall is conservative."

The Licensee should define and discuss these " adequate provisions."

8. With regard to the in-plane effects, the strength of the strut corresponding to a strain at cracking is given in expression (1) of Section 6.5 of Enclosure 3 [2]. The Licensee should provide a complete derivation of this expression and discuss how this expression relates to the permissible strain levels of unconfined and confined walls.

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The Licensee should discuss and justify the boundary conditions used in the analysis of the 14 walls mentioned in Reference 3.

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10. The Licensee plans to provide steel brackets to reinforce the end spans of the north and south walls of the elevator shaft. The Licensee should evaluate the out-of-plane drift effects that would result from these brackets.

11.

With reference to the in-plane effects for factored loads (Section 6.5 of Enclosure 3 [2]), a factor of 1.67 was introduced to the allowable in-plane strain. The Licensee should provide the technical basis for this factor.

12.

With regard to the " Energy Balance Technique" and the " Arching Theory" [2), the Licensee should not resort to these approaches, if possible.

p 13.

The modulus of elasticity for grouted or solid walls was varied from 600 fa' to 1200 f,'. ACI 531-79 [6] recommends a maximum of 1000 f,'.

If the Licensee selects 1200 Ka' in the analysis, an explanation should be provided. ~

l 14.

With regard to the collar joint strength, the Licensee used the same test value that was used for the Trojan plan 3. The Licensee thould

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l discuss walls.

the applicability of - utis test to the THI unit 1 masonry In Reference 3, the Licensee proposed that the collar joints of multiple wythe block walls be filled with non-shrink Portland l

cement grout. The Licensee should provide technical data to support ~

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< the use of this grout and indicate how this repair will strengthen the collar joint. Furthermore, dae ~ Licensee should clarify whether l the auxiliary building has any multiple wythe block walls and, if i

l not, explain why this proposed modification was introduced.

B-2 ranklin Research Center A Casaca of The Frankhn insamme

s. p TER-C550 e -159

15. With regard to shear for reinforced masonry, the Licensee introduced test results on shear strength of reinforced masonry. Specifically, Figure 2 of Enclosure 3 [2] presented test data for various percentages of reinforcement. For the case in which there is more than 0.3% horizontal reinforcement, there is only one test value for M/VD = 1.0 and there are two test values for M/VD = 0.5. For the case in which there is less than 0.3% horizontal reinforcement, l there are no test data for N/vD = 1.0. The data presented do not l appear to be sufficient to justify use of these values. The '

Licensee should discuss the technical basis for the applicability of these tests to the masonry walls at TMI Unit 1 with respecc to the mortar typg, boundary conditions, and nature of the loads (i.e. ,

dynamic, static) and should identify and provide the source of these tests.

j 16. With regard to shear for unreinforced masonry, a factor of 1.5 was i

introduced for allowable shear 3 for factored loads. SEB criteria [4]

suggest a factor of 1.3. The Licensee should provide any literature or test data to support the use of a factor of 1.5.

17. With regard to allowable tensile stresses normal to bed joints, SEB criteria [4] suggest a factor of 1.3 for factored loads. The Licensee should discuss and justify the use of a factor of 1.5. The Licensee should also discuss the applicability of those tests mentioned in Section 5.1.5 of Enclosure 3 [2] to the TMI Unit 1 masonry walls.

18. With regard to bond stress, the Licensee should discuss and justify an increase of 33-1/3% for factored loads.

19. Indicate the intended action to evaluate wall AB-14.

20. Provide the schedule for the propoced modifications specified in Reference 3.

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TER-C5506-159 REFERENCES

1. IE Bulletin 80-11

" Masonry Wa11 Design" NRC, May 8, 1980

2. H. D. Hukill (Director, TMI Unit 1, Metropolitan Edison Company)

Letter with enclosures to B. H. Grier (NRC)

November 17, 1980

3. Metropolitan Edison Company "Three Mile Island Unit 1 - Reevaluation of Safety-related Concrete Masonry Walls, NRC IE Bulletin 80-11" Topical Report No. 001, Rev. O July 14, 1981

4. Standard Review Plan, Section 3.8.4, Appendix A

" Interim Criteria for Safety-Related Masonry Wall Evaluation" NRC, July 1981-

5. Uniform Building Code International Conference of Building Officials, 1979

6. ACI 531-79 and Commentary ACI 531-R-79

" Building Code Requirements for Concrete Masonry Structures" American Concrete Institute, 1979 3

7. ATC 3-0 6 i

" Tentative Provisions for the Development of Seismic Regulations for Buildings" Applied Technology Council, 1978 '

8. " Specification for the Design and Construction of Ioad-Bearing

. Concrete Masonry" National Concrete Masonry Association (NCMA), August 1979

9. Standard Review Plan, Section 3.7.2

" Seismic System Analysis" NRC, July 1981 l! nklin Research Center A Dhee an of The Frenedm anasue

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l APPENDIX C 1

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