ML20002A229
| ML20002A229 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 10/28/1980 |
| From: | Parker W DUKE POWER CO. |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8011050390 | |
| Download: ML20002A229 (6) | |
Text
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DUKE POWER COMPANY Powsm Buturwo 422 Sourn Causcu Srazzi. CHAmmns. N. C. asa4a WIWAld C. PAR A ER. JR.
October 28, 1980 VtCe PetSietaf Strs= PeoowCrio=
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Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. B. J. Youngblood, Chief Licensing Projects Branch No. 1 L.
Subject:
McGuire Nuclear Station, Units 1 and 2 Docket No. 50-369, -370
Dear Mr. Denton:
As requested by Mr. Ralph Birkel's telecopy of October 16, 1980, please find attached additional information on Category I Masonry Wall Design at McGuire Nulcear Station.
Note that this response supplements ey letters of September 23, 1980, September 16, 1980 and July 2, 1980. Please advise if you have additional questions.
Very truly yours.
(sk/A' w 0. 90
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William O. Parker, Jr. h LJB:ses Attachment ff s
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MCGU2RE NUCZ, EAR STATION UNITS 1 AND 2 i
Response to NRC Request for Additional Information October 16, 1980 8.
In your response (2) you implied that the McGuire masonry wall activities were accomplished before the issuance of SRP, therefore SRP should not be applied. This is not consistent with staff's position. The staff uses current criteria to evaluate even nuclear power plants which are in operation.
In view of this, it is required that an evaluation of the masonry wall design should be made on the i ssis of ACI 531-79 Code. Justification should be provided for any design deviation from the requirements of this edition of Code.
The design of the McGuire masonry block walls was originally based on the requirements of ACI Committee 531 report, Title No. 67-23. The design is also in full compliance with ACI-531-79 code without deviation.
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9.
In your response to questions 3 and 4iyou stated that because of your use of assumptions such as rigid wall and simply supported end conditions together with a design factor of 1.875, no rigorous response spectra type of analysis is required and it is reasonable to conclude that tha masonry wall design approach is reasonable, adequate and conservative.
Your conclusion is not so obvious to the staff.
From attachment 7 for a structure or structural element having a period of 0.08 second the response i
acceleration is found to be 0.5 (broadened) vs. 0.16 for zero period. The factor is 0.5/.16 = 3.125 vs.1.875. In the reinforcing details provided (attachment #9) especially at corners, the reinforcing steel _is placed either on one face or at the middle of the second.
In view of these l
observations it is requested that in order to substantiate your conclusion i
a rigorous response spectra analysis be performed taking into consideration such factors as interstory drift, effect of upper floor response, actual support condition, etc.
In accordance with your request, a (etailed response spectrum re-analysis program has been initiated to rigorously evaluate the masonry walls as flexible attachments to the primary structure.
In the analysis of each wall, the wall will be considered to be subjected to an input spectra equivalent to the average of the floor and ceiling response spectra of the supporting building. Wall support boundary conditions will be appropriately chosen to maximize the seismic intertial loading applied to the wall.
With regard to interstory drift effects, each wall will be evaluated considering the maximum displacements of the Auxiliary Building. In-plane effects will be evaluated on the basis of gross panel shear strain by a calculation of
~O H IGHT y = ( top bot Test data frcm the references listed in Attachment 11 indicate that panel failure characterized by diagonal cracking due to this type of effect will not be initiated prior to a value of y =.0001 for unconfined panels. As stated in response (4), a factor of safety of at least 1.88 exists against this type of failure, even neglecting the confining effects of the building's reinforced concrete frame.
10.
In your response 4(a) you stated that for collar joints in multiple wythe walls mortar was applied to adjoining faces of both wythes and pressed firmly to insure full bond between wythes, thus constituting a shear transform mechanism between wythes. From your computation check the resulting shear stresses due to the intertial loads are found to be about 11 psi. Since shear in collar joints is different from shear in other joints, indicate what the allowable value for such shear is and how it is established.
At the time of the original design, the topic of collar joint shear was not addressed in any building code and was therefore not checked in the original design calculation. Our stated value of 11 psi was arrived at by considering the placement of hypothetical extremely tall multi-wythe wall at the worst possible location in the Auxiliary Building.
In actuality, such a wall does not exist. Typical actual SSE values of peak collar joint shear stresses due to inertial loads are as follows:
Elev. 767'+0" 4.83 psi Elev. 750'+0" 4.46 psi Elev. 733'+0" 7.97 psi Elev. 716'+0" 8.79 psi The only data on collar joint shear stress which is presently available is that which resulted from investigation of masonry walls at Trojan Nuclear Plant, in which the value of 12 psi was determined to be an acceptable limit for collar joint shear stresses.
In light of the actual values, which are significantly lower than 12 psi, we conclude that the masonry wall design for multi-wythe walls is conservative.
2
j 11.
In your response 6(a) discussing the effects of the combined action of local and global loads, you stated that. local loads are considered as global in-plane 4
loads only when they are of significant magnitude.
Indicate your criterion i
"-ir ificant magnitude",
i il attachments at McGuire Nuclear Station are limited to extremely low suau nevels. Attachment 12 gives a summary of typical hanger loads at the point of attachment to masonry walls. The typical loads shown include the maximum in-plane vertical and longitudinal attachment reactions which are imposed on concrete masonry walls at McGuire Nuclear Station. As can be seen from this table, flexural moment loading and transverse loads will j
dominate in all cases. Typical in-plane stresses resulting from these in-plane loads will be on the order of 0.6 psi in the immediate area of the attachment. This is not deemed to be a significant factor in the design of these masonry walls.
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i ATTACHMENT 11 In-plane Interstory Drift References P
Becica. I. J. and H. G. Harris " Evaluation of Techniques in the Direct Modeling 1
of Concrete Masonry Structure", Drexel University Structureal Models Laboratory
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Report No. M77-1, June 1977.
Fishburn, C.
C., "Effect of Mortar Properties or Strengths of Masonry", National Bureau of Standards Monograph 36. U.S. Government Printing Office, November 1961.
Mayes, R. L.; Clough, R. W.; et al. " Cyclic Loading Test of Masonry Piers" 3 volumes EERC 76/8,78/28,79/12 Earthquake Engineering, Research Center, College of Engineerir.g University of California, Berkeley, CA.
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ATTACHMENT 12 Typical Attachment Loads for Masonry Walls McGuire Nuclear Station Units: Pounds, Inches (transverse)
(vertical)
(longitudinal)
M2
& Mz Hanger #
Connection Point Fx Fy Fz MCA-lKD-102 1
42 85 58 511 and MCA-lKD-103 MCA-lKD-130' 1
647 60 1920 and MCA-lKD-131 2
593 76 2450 30 3
MCA-lKD-181 1
107 31 2 ~
98 103 MCA-lKD-182 1
93 5
55 2
90 9
71 83 MCA-lKD-183
'l 60 380 2160 MCA-lKD-188 1
63 50 126 MCA-1KD-204 1
37 7
54 2
37 32 38 MCA41KD-205 1
37 7
54 2
37 29 38 MCA-1KD-250
'1 51 31 75 6
2 51 31 75 6
MCA-lKD-256 1
187 45 6
4 77 246 MCA-lLD-112 1
131-15 195 2
131 15 20 100 3-98 83 138
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