ML20129K082
| ML20129K082 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Haddam Neck, 05000000 |
| Issue date: | 07/22/1985 |
| From: | Zwolinski J Office of Nuclear Reactor Regulation |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| IEB-80-11, LSO5-85-07-028, LSO5-85-7-28, NUDOCS 8507230372 | |
| Download: ML20129K082 (10) | |
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July 22, 1985 Docket Nos. 50-213/50-245 LS05-85-07-028 Mr. John F. Opeka, Senior Vice President Nuclear Engineering and Operations Connecticut Yankee Atomic Power Company and Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141
Dear Mr. Opeka:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - MASONRY WALL DESIGN Re:
Haddam Neck Plant and Millstone Nuclear Power Station, Unit No. 1 i
By separate letters, dated November 4, 1980, Northeast Utilities (NU) provided their responses'to IE Bulletin 80-11, Masonry Wall Design for the Haddam Neck Plant and Millstone Unit 1.
By letter dated December 3, 1982, NU provided responses to requests for additional infonnation (RAI) for both -
the Haddam Neck Plant'and Millstone Unit 1.
The staff contractor has reviewed your submittals and responses to the RAI and has concluded that the enclosed additional information is required to complete its review. Attachment I contains RAI for the Haddam Neck Plant and Attachment 2 contains RAI for Millstone Unit 1. is provided for reference and describes the staff position on arching action theory to qualify unreinforced masonry walls.
In order to expedite the review schedule, we suggest that a site visit / audit meeting be arranged in late September or early October,1985 to review calculations and discuss the responses to the enclosed RAI. We anticipate that both Millstone Unit I and Haddam Neck units can be discussed at the same meeting given the similarity of the responses to the IE Bulletin. The proiect managers for Haddam Neck and Millstone Unit I will be working with your staff to arrange the technical meeting and the subsequent site visits.
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8507230372 050722 PDR ADOCK 05000213 G
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Mr. John F. Opeka July 22, 1985 The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under PL 96-511.
Sincerely,
,%d sys John A. Zwolinski, Chief Operating Reactors Branch #5 Division of Licensing Attachments:
As stated
,: w/ attachments:
See next page DISTRIBUTION Docket File NRC PDR Local PDR ORB #5 Reading HThompson OELD l
EJordan BGrimes JPartlow FAkstulewicz JShea CJamerson JZwolinski l
ACRS(10) l NChokshi i
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DL: OR DL: ORB #5 JZwolinski CJamerson V FAkstulewicz:jb JShep/85
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Mr. John F. Opeka Haddam Neck Plant &
Connecticut Yankee Atomic Power Company Millstone Nuclear Power Station, Northeast Nuclear Energy Company Unit No. I cc:
Gerald Garfield, Esquire Kevin McCarthy, Director Day, Berry & Howard Radiation Control Unit Counselors at Law Department of Environmental City Place Protection Hartford, Connecticut 06103-3499 State Office Building Hartford, Connecticut 06106 Edward J. Mroczka Vice President, Nuclear Operations Board of Selectmen Northeast Utilities Service Company Town Hall Post Office Box 270 Haddam, Connecticut 06103 Hartford, Connecticut 06141-0270 Superintendent State of Connecticut Haddam Neck Plant Office of Policy and Management RFD #1 ATTN: Under Secretary Energy Post Office Box 127E Division East Hampton, Connecticut 06424 80 Washington Street Hartford, Connecticut 06106 Resident Inspector Haddam Neck Plant c/o U.S. NRC East Haddam Post Office East Haddam, Connecticut 06423 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 631. Park Avenue King of Prussia, Pennsylvania 19406 Northeast Nuclear Energy Company ATTN:
Superintendent Millstone Nuclear Power Station P. O. Box 128 Waterford, Connecticut 06358 Resident Inspector c/o U.S. NRC Millstone Nuclear Power Station P. O. Box 811 Niantic, Connecticut 06357 First Selectman of the Town of Waterford Hall of Records 200 Boston Post Road Waterford, Connecticut 06385
4 ATTACHMENT 1 REQUEST FOR ADDITIONAL INFORMATION MASONRY WALL DESIGN, IE BULLETIN 80-11 HADDAM NECK PLANT DOCKET NO. 50-213 1.
In Response 17 of Reference 1, Connecticut Yankee Atomic Power Company (CYAPCo) indicated that the seismic evaluation of masonry walls used estimated floor spectra based on the Interim Seismic Design Ground Spectrum and that this criterion was later compared to the SEP floor response spectra.
Provide the conclusions that were drawn from this comparison and clarify whether the SEP spectra were actually used.
2.
With respect to Attachment 2 in Reference 1, explain how the wall attachment weights were determined.
Indicate why these forces are divided by the area of the entire wall.
3.
With respect to Attachment 5, Section 5.1 (Appendix A) in Reference 1, CYAPCo indicates that allowable stresses can be increased by 33% for OBE seismic loadings. However, the SGEB criteria, Section 3(a),
expressly forbid the increase of allowable stress when wind or seismic loads (OBE) are involved. CYAPCo should identify the walls that require an increase in allowable stress for OBE load combinations in order to be qualified. Also, provide the actual percentage increase in allowable stress that is needed to qualify these walls.
4.
In Response 11 of Reference 1, CYAPCo indicated that all allowable stresses were increased by a factor of 1.67 for load cases involving SSE. The SGEB criteria pennit increase factors of only 1.3 for masonry shear and tension normal to the bed joint and 1.5 for tension parallel to the bed joint. CYAPCo should identify those walls which would not qualify if the SGEB factors were used and provide the percentages by which the SGEB factored allowables are exceeded.
5.
Identify the total number of walls that required modifications in order to be qualified under the SGEB criteria (2). Also, indicate how many of these are unmortared walls.
6.
In Response 8 of Reference 1, CYAPCo stated that one wall at the Haddam Neck plant was analyzed using the " arching action" technique.
Identify this wall. The NRC position on this issue states that the use of the arching action theory to qualify unreinforced masonry walls is not acceptable. These walls should be repaired so they can be qualified based on the SGEB criteria (2).
(The NRC position is provided as ).
7.
Identify whether any QA/QC records are available to ensure conformance of masonry construction to design drawings and specifications.
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REFERENCES f
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W. G. Counsil Letter with attachments to R. A. Clark (NRC)
Subject:
Request for Additional Information on IE Bulletin 80-11, Masonry Wall Design Northeast Utilities December 3, 1982 SGEB Criteria for Safety-Related Masonry Wall Evaluation 2,
Developed by the Structural and Geotechnical Engineering Branch (SGEB) of the NRC July 1981 O
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ATTACHMENT 2 REQUEST FOR ADDITIONAL INFORMATION MASONRY WALL DESIGN, IE BULLETIN 80-11 MILLSTONE NUCLEAR POWER STATION UNIT 1 DOCKET N0. 50-245 1.
In Response 10 of Reference 1, Northeast Nuclear Energy Company (NNECO) indicated that the seismic evaluation of masonry walls used the floor accelerations of the original design multiplied by a factor of 5 (Response
- 6) and that this criterion would be compared with the SEP floor response spectra. Provide a summary of this comparison and the conclusions drawn l
from it and clarify whether the SEP spectra were actually used.
2.
Identify the 24 walls that have been qualified by arching action. The NRC position on this issue states that the use of the arching action theory to qualify unreinforced masonry walls is not acceptable. These walls should be repaired so that they can be qualified based on the SGEB criteria (3).
(The NRC position is enclosed as Attachment 3).
3.
Identify the number of walls that required modifications in order to be qualified under the NNEC0 reevaluation criteria, and specify how many of these can be qualified under the SGEB criteria (3) design method after modification.
4.
Exhibit C-2 in Attachment 2 of Reference 2 lists the allowable shear stress for reinforced walls in flexure as 1.1-/Trii; this agrees with ACI 531-79. However, the revised Exhibit C-2 in Attachment 6 of Reference 1 lists the allowable value for out-of-plane shear as 1.5 4Trj;p. Explain why this value was chosen for reinforced walls.
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5.
Exhibit C-2 in attachment 2 of Reference 1 indicated that an increase factor of 1.5 for allowable masonry shear stress wa used for reinforced walls.
If a basic allowable of 1.5 m was used (as suggested by Exhibit C-2 [1]) and an increase factor 1.5 was applied to it, that would be equivalent to applying an increase factor of about 2 to the basic allowable found in ACI 531-79, which is 1.1 i f'm.
The SGEB criteria [3], however, allow an increase factor of only 1.3 l
for masonry shear.
Indicate whether the maximum shear stress in the reinforced walls still meets the SGEB criteria, which is based on ACI l
531-79.
If any walls would not qualify, provide the percentages by l
which the SGEB allowables are exceeded.
6.
Indicate whether any walls at the Millstone Unit I were built without mortar.
If so, the walls must be modified so that loose blocks do not impact safety-related equipment. Provide some sample sketches or drawings of this type of modification if applicable to this plant.
l 7.
Identify whether any QA/QC records are available to ensure conformance of masonry construction to design drawings and specifications.
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REFERENCES 1.
W. G. Counsil Letter with attachments to R. A. Clark (NRC)
Subject:
Request for Additional Information on IE Bulletin 80-11, Masonry Wall Design Northeast Utilities December 3, 1982 Enclosure II 2.
W. G. Counsil Letter to B. H. Grier, NRC
Subject:
Millstone Nuclear Power Station, Unit 1 - IE Bulletin 80-11, Masonry Wall Design Northeast Utilities November 4, 1980 A01021 3.
SGEB Criteria for Safety-Related Masonry Wall Evaluation
. Developed by the Structural and Geotechnical Engineering Branch (SGEB) of the NRC July 1981 m
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ATTACHMENT 3 SGEB Staff Position on Use of Arching Action Theory to Qualify Unreinforced Masonry Walls in Nuclear Power Plants INTRODUCTION Unreinforced hollow block masonry walls have a very limited capacity under the action of out-of91ane loads.
Higher resistance could be dev' eloped by' creating large in-pl$ne clamping force $,'thereby forming a three hinged arch mechanism after mid-span and s'upport flexural cracking has occurred.
The most important conditions'for the arching mechanism to develop are the existence of rotational restraint at the boundaries and the prevention of gross sliding of the wall at support section's.
Some of the licensees have relied on the development of this arching mechanism (referred to herein as ' arching action theory') to qualify unreinforced masonry walls in their plants.
The staff and their consultants have reviewed the basis provided by licensees to justify the use of arching action theory to qualify the unreinforced resonry walls.
The staff met with a group of licensees representing approximately eleven utilities and twenty two units on November 3,1982 and January 20, 1983 to discuss this issue.
Further, a
1 2-site visit and detailed review of design calculations were conducted by the staff and consultants to gain first-hand knowledge of field conditions and the application of arching action theory in qualifying i
in-place masonry walls.
Based on the information gained through the above activities, the staff has formulated the following position on the acceptability of the use of arching action theory to qualify unreinforced masonry walls in operating nuclear power plants.
The staff's technical basis for the position is discussed in the attached repo r't.
POSITION The use of arching action theory to qualify unrei.nforced masonry block walls is not acceptable. Therefore, the licensee shall fix the walls currently qualified by the use of arching action theory such that they
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meet the staff acceptance criteria based on the working stress approach, i
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ENCLOSURE'TO ATTACHMENT O
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EVALDATION OF ABC21NG TEEORY IM UMtEINFOICED MhS0800f MkIJJ IN NUCLEAR POWER FIJJfTS e
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5 Prepared by 1
Ahmed A. Banid Barry G. Earris 2
vu Con June 1983 1.
Department of Civil Engineering, Drexel University 2.
Nuclear Engineering Department, Franklin Research Center m - a n A n n /r e
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ItrIRODUCTION In response to IE Bulletin 80-11, a total of 16 nuclear power plants have indicated that the arching action technique has been employed to qualify some unreinforced masonry walls.
Based on the review of submittals provided by the licensees and published literature, Franklin Research Center (F E) staff and FE consultants have concluded that the available data in the literature do not give enough insight for understanding the mechanics and performance of unreinforced masonry walls under cyclic, fully reversed dynamic loading.
As a result, a meeting with representatives of the affected plants was held at the NE on November 3,1982 ao that the NE, FRC staf f, and FRC consultants could explain why the applicability of arching theory to nasonry walls in nuclear j
power plants is questionable (1).
In a subsequent meeting on January 20, l
1983, consultants of utility companies presented their rebuttals (2) and requested that they abould be treated on a plant-by-plant basis.
In accordance with their requests, the NE staff has started the process of evaluating each plant on an individual basis.
In this process, the N E, F M staff, and consultants have initiated visits to various nuclear plants to i
examine the field conditions of unreinforced masonry walls in the plants and to gain first-hand knowledge on how the arching theory is applied to actual walls.
Eey calculations have been reviewed with regard to the arching theory, i
EVALUATION OF AERING TREORY l
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Test of unreinforced concrete masonry walls were recently conducted by Agbabian Associates, S. 3. Barnes and Associates, and Kariotis and Associates (3) (this joint venture work is designated as ASK). Based on the visit to Oconee Nuclear Station, the results of the AEK tests, and all relevant information submitted by the licensees including the rebuttals given by the licensees in the January 20, 1983 meeting, the N E, FRC staff, and consultants have made the following evaluations:
1.
The design methodology used at various nuclear plants was developed by McDowell et al. [4] in 1956 for solid brick walls under static monotonic loading.
No test data are available to check the adequacy of hollow block masonry under cyclic, fully reversed dynamic loading.
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Se only dynamic test data for arched masonry walls are the Uns tests
[5] for blast loading. Bis type of loading is not a true represen-tation of earthquake loading because it is not fully reversed and has a decayed nature. Under very abort-duration blast loading, ansonry walls, which have auch lower natural frequencies, would not fully respond to the applied load.
In addition, only two walls were tested under cyclic blast loading at URS for arched masonry walls.
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3.
Extrapolation of test data from solid masonry to hollow block masonry l
is questionable. Recent test data (6) of eccentrically loaded ansonry assemblages showed that the failure mechanism, strain distribution, and overall behavior of hollow masonry are quite different from those of solid or grouted masonry.
4.
Rollow block masonry walls are more susceptible to premature web-shear failure or crushing compression failure. Precluding these types of failure is neccesary for the development of the arching mechanism. No data are available at the present time to determine the safety factors against these brittle failures under seismic loading.
5.
Recent ASK dymanic tests [3] showed that unreinforced block masonry walls did fail (collapse) under earthquake loads with ground acceleration (effective peak acceleration) of about 0.3g to 0.49, which is typical for nuclear plants. Also, some walls experienced local crushing at the base before failure by instability, which emphasises the possibility of premature compression failure of arched walls.
It must be noted, however, that the ARK test walls were not i
restrained at top to develop arching. De effect of boundary conditions could be significant and cannot be evaluated without further testing.
j 6.
Unreinforced block masonry walls are extremely brittle, and flexural ~
failure occurs without warning. D e sensitivity of unreinforced l
masonry to crack development due to temperature and shrinkage is evident. Also, the inherent strength variability indicates the necessity of different safety indexes in ultimate failure analysis.
7.
Masonry walls in nuclear plants usually have openings and attachments. Deir effects on wall stability under seismic loading are unknown and cannot be rationally evaluated without testing.
8.
No test data are available for gapped arching block walls under cyclic loading. In some cases, restrainers are provided around the gap to prevent gross sliding; this repair measure does not necessarily change the wall behavior from gapped arch to rigid arch...
CONCLUSICBI A review and evaluation of the available information on the applicability of arching theory to unreinforced masonry walls in nuclear power plants has been presented.
ME, FK staff, and consultants are firmly convinced that their original position expressed to the licensees in the November 3,1983 meeting is still valid.
It is evident that test data are needed to quantitatively determine the effects of different wall geometries, material properties, and boundary conditions on unreinforced block masonry walls' resistance to earthquake loading.
It is recommended that a confirmatory testing program be performed to investigate the applicability of arching theory to unreinforced block masonry walls in nuclear power plants.
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EEFERENCES l
1.
manid, A. A. and Barris, E. G.,
" Applicability of Arching Theory to Unreinforced Block Masonry Walls Under Earthquake Loading,' Pranklin Research Center, Philadelphia, PA August 1982 2.
' Rebuttal to Applicability of Arching Theory to Dnreinforced Block Masonry Walls Under Earthquake Loading,' Computech Engineering Services, Inc., URS/J. A. Blume & Associates and Bechtel Power Corporation, January 1983 3.
' Methodology of Mitigation of Seismic Eazards in Existing Unreinforced Masonry Buildings:
Wall Testing, out-of-Plane,"
ARK report, El Sequndo, CA 1981 4.
McDowell, E. L., McKee, M. E., and Sevin, E., " Arching Action Theory 2
of Masonry Walls,' ASCE Proceedings, Journal of the Structural Division, ST2.
March 1956 5.
Gabrielsen, B., Wilton, C., and Esplan, E., " Response of Arching Walls and Debris from Interior Walls Caused by Blast leading," Report No. 7030-23, URS Research Company, San Mateo, CA Pobruary 1975 6.
Drysdale, R. G. and Basid, A. A., ' Capacity of Concrete Block Masonry Prisons Under Eccentric Compressive Loading,' ACI Journal, Proceedings, Vol. 80 March-April 1983 i
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