ML19351D824
| ML19351D824 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 11/04/1980 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| A01021, A1021, IEB-80-11, NUDOCS 8011200079 | |
| Download: ML19351D824 (16) | |
Text
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CONNECTICUT YA N K EE ATO M IC POWER COMPANY BERLIN. C O N N E CTIC U T P O JOX 270 H ARTFORD. CONN ECTICUT 04101
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November 4, 1980
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Docket No. 50-213 3
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.wr Mr. Boyce H. Grier, Director b
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Office of Inspection and Enforcement co
~S U. S. Nuclear Regulatory Commission lj w
631 Park Avenue King of Prussia, PA 19406 Refeiences:
(1)
B. H. Grier letter to W. G. Counsil dated May 8, 1980, forwarding I&E Bulletin No. 80-11.
(2)
W. G. Counsil letter to B. H. Grier dated July 7, 1980.
Gentlemen:
Haddam Neck Plant I&E Bulletin No. 80-11 Masonry Wall Design In Reference (1), the NRC Staff requested that Connecticut Yankee Atomic Power Company (CYAPCO) provide information concerning the Msign and construction of concrete masonry walls at the Haddam Neck Plant.
CYAPC0 provided the response to Item 1 of Reference (1) in Reference (2).
This included log sheets describing the masonry walls at the Haddam Neck Plant and the safety-related systemr and equipment in proximity to these walls.
Included on the log sheets was the priority by which these walls will be re-evaluated in accordance with Item 2 of Reference (1), and the basis for the prioritization.
The acceptance criteria by which the re-evaluation of the concrete masonry walls will be based, is provided as Attachment 1.
As was reported in Reference (2), these criteria have been extracted from existing building codes ai d test data.
These criteria, while deve'.oped specifically for the Haddam Neck Plant, were derived from generic methodologies obtained through literature searches, existing codes and data, and extensive work by our consultant in the area of concrete masonry.
Included in Attachmeat 1 is the re-evaluation procedure which is being used for the masonry walls at the Haddam Neck Plant.
8 01120 00 D
- CYAPCO's philosophy, with respect to the masonry re-evaluation program, is to ensure that a conservative margin of safety exists for all concrete masonry walls at the Haddam Neck Plant when analyzed for the loading conditions described herein. This is achieved by performing ' preliminary'
.e-evaluation analyses utilizing conservative assumptions and acceptance criteria to estimate the margin of safety in the masonry walls.
The conservative nature of this approach will result in the modification of masonry walls that could be illustrated to perform satisfactorily if these walls were submitted to additional, sophisticated analyses to eliminate unquantified margins of safety.
In this way, resources are directed toward design and modifications to increase the margin of safety in the masonry walls rather than into additional analyses.
The past refueling outage at the Haddam Neck Plant afforded the op Nrtunity to complete detailed walkdowns in normally inaccessible areas of the plant. The scope of the program to respond to I&E Bulletin No. 80-11 includes 40 masonry walls in accessible areas and one (1) inaccessible masonry wall.
vane of the masonry walls at the Haddam Neck Plant support any safety-re.1ated piping systems nor are they utilized as resisting elements for horizontal building inertial forces.
The scope of the effort required to adequately respond to I&E Bulletin No. 80-11 in terms of the preparation of as-built data and the develop-ment of design criteria has resulted in a commitment of formidable engineering resources throughout the industry.
It has become evident that the re-evaluation of concrete masonry walls for the postulated loads and load combinations described herein will require an extensi]n of the completion date beyond that documented in Item 4 of Reference (1).
The effort to develop design criteria has required extensive research into existing code acceptance criteria.
This was necessary in order to divest the conservatisms inherent in design procedures from factors affecting the ultimate structural behavior of the ra m nry walls.
CYAPC0 notes that had a masonry wall test program been selected as a means of quantifying safety margins, an extension beyond the 180 day reporting requirements would be acceptable.
This is documented in Item 3 of Reference (1).
The lack of a commitment to such a program for the Haddam Neck Plant should not be construed to mean that criteria develop-ment and re-evaluation of the effected walls is any less complex.
CYAPC0 anticipates that the re-evaluation of the concrete masonry walls at the Haddam Neck Plant and any modifications to these walls as a result of the re-evaluation will be completed by April 1,1981.
A final report is scheduled to be docketed at that time.
To date, the re-evaluations of the masonry walls at the Haddam Neck Plant are forty percent (40%) complete.
- We trust you find this information responsive to the Reference (1) requests and concur with our request for an extension as outlined above.
CYAPC0 remains available to discuss any of the information provided to the Staff to date.
Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY
- i. I/rfAAa W. G. Counsil Senior Vice President l
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STATE OF CONNECTICUT )
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Then personally appeared before me W. G. Counsil, who being duly sworn, did state that he is Senior Vice President of Connecticut Yankee Atomic Power Company, a Licensee herein, that he is authorized to execute and file the foregoing information in the name and on behalf of the Licensees herein and that the statements contained in said information are true and correct to the best of his knowledge and belief.
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Notary Public 1
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Docket No. 50-213 Haddam Neck Plant I&E Bulletin No. 80-11 9
November,1980 w
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CRITERI A TO REEVALUATE MASONRY WALLS ~
i.0 Introduction This criteria is applicable to the reevaluation of'the masonry walls at the Connecticut Yankee nuclear power plant as required by the United States Nuclear Regulatory Commission (NRC) l&E Bulletin 80-11.
Characteristically, the masonry walls at this plant are constructed as non-structural partition and shield walls.
None of these masonry walls have been incorporated into the lateral load resisting system or as major load bearing walls.
Furthermore, these masonry walls are predominantly composed of hollow, single wythe construction with mortar joints between the masonry wall and ad-joining structural elements.
All safety-related walls will be reevaluated for all loads and load combina-tions defined herein; the reevaluation will include the global response and the local transfer of the equipment loads to the walls.
Revisions of this criteria to address special cases not covered in this document will be pre-sented with the necessary supporting documentation to the NRC for review.
2.0 Loads and Load Combinations 2.1 Loads. The reevaluation will consider all relevant loads and load com-binations specified in the FDSA for concrete design. The field survey of all safety-related masonry walls at the plant concluded that none of these walls i
are subjected to loads from tornado, wind, misslie, thermal gradients, pres-i 1
sure differentials, pipe whip, or jet Impingement. Thus only seismic loads need to be considered in addition to dead and live loads. The following two
. I
a procedures shall apply to seismic loads.
i 2.1.1 Wall inertial Loads: Inertist loads due to earthquake loading will be based on the " Interim Seismic Design Ground Spectrum for CY" currently under-going review by the NRC as part of the Systematic Evaluation Program (SEP).
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This site spectrum curve for the Safe Shutdown Earthquake (SSE) is only l
preliminary and utilizes a peak horizontal ground acceleration of.17g.
Con-t servative estimates of ampilfying the ground spectrum to various floor levels of the different buildings will be made from this ground spectra for analysis and design of the masonry walls. Af ter the SEP detailed dynamic analyr.is is com-plated for the various buildings, the actual floor response spectrum values t
for the walls at different elevations located in the various buildings will be compared to the assumed conservative estimates to insure that the analysis and design of the masonry walls is adequate.
Seismic Input to the masonry walls will be as defined by the appropriate floor response spectra at the i
base and top of the well; the maximum response from the use of either floor spectrum will be used in the analysis and design.
2.1.2 Equipment inertial loads: The subject of equipment support loads imposed on the walls is an area that requires further Investigation and will be addressed in the next revision of this criteria.
1 2.2 Combination of Responses Due to Different Components of Ground Motion.
Codirectional wall and equipment responses due to eacn horizontal component of ground motion will be combined on an absolute sum basis with responses due to the vertical component of ground motion.
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2.3 Load Combinations.
The reevaluation of masonry walls will consider the following load combinations:
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Load Category Load Factors 1
o L
E HE 1.0 1.0 1.0 Severs Environmental Extreme Environmental 1.0 1.0
1.0 whert
0 = Gravity load of masonry wall and attachments L = Live load E = OBE inertial loads f rom masonry wall and attachments HE = SSE Inertial loads f rom masonry wall and attachments 3.0 Material Properties For the determination of the strength and stiffness of the structures, the material properties will be taken as the minimum specified for the masonry, mortar, grout, and steel specified in the contract drawings and documents (See Table 1).
Testing for material properties may be used in lieu of the minimum specified.
Such testing will follow testing procedures defined in American Concrete Institute (ACI'), " Building Code Requirements for Concrete Masonry Structures" (ACI 531-79).
If testing other than those defined in ACI.531-79 are to be used, a description of the testing program and proce-dures for using test data will be submitted to the NRC for review and comment.
TABLE 1 MATERIAL PROPERTIES - CY BLOCK WALLS Connecticut Yankee Power Plant 1.
Concrete Block Units a)
Exterior or load bearing partitions ASTM C90, Grade A b) Non load bearing partitions ASTM Cl29 c)
Solid block units ASTM C145, Grade B d)
Lightweight block uriits ASTM C90, Grade B 4
2.
Mortar ATSM C270, Type N 3
Reinforcement A305 and AIS l.
Damping in concrete masonry walls may be taken as 4% of critical for severe environmental load combinations and 7% of critical may be used for extreme environmental load combinations.
4.0 Analysis Procedures Masonry wall stresses shall be calculated on the basis of the following analysis procedures.
Several acceptable procedures are defined herein reng-Ing from the simplest and most conservative to the more rigorous and realistic.
If more sophisticated analysis procedures are to be used, a description of i
such procedures will be presented to the NRC for review and comment.
4.1 Frequency Calculations.
In-plane fundamental frequencies of masonry walls will be calculated using values for modulus of elasticity as defined in Section 5, moments of inertia defined by the gross cross section and the mass of. wall and all attachments.
4.1.1 Non-load bearing walls: Walls supported along all four edges will be assumed rigid (i.e., fundamental frequency greater than 33 hert2.) in their own plane.
In-plane frequency of all other walls will be calculated using standard dynamic analysis procedures.
Out-of-plane fundamental frequencies of masonry walls will be calculated on the basis of elastic plate theory with appropriate boundary conditions.
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4.1.2 Valls with openings:
Fundamental frequency of piers alongside open-ings in masonry walls will be calculated on the basis of a simply supported beam spanning the height of the opening and having the cross section of the pier.
4.1.3 Load bearing walls:
Fundamehtal frequency of load bearing walls within 1
the buildings will be calculated using standard dynamic analysis procedures, with adequate representation of any tributary masses.
4.2 Acceleration Response of the Walls.
Given the seismic Input to each wall as defined in Section 2.0 and the fundamental frequency of the wall, the applied out of plane load on the wall shall be defined by a uniform load w where:
,= 1.3 S,m (1) w
, = Applied out of plane uniform load in the direction of w
ground motion S, = Spectral acceleration for the fundamental frequency of the wall. The value of S, shall be from governing floor response spectra as defined in Section 2.0 and for wall damping as defined in Section 3.0.
m = Mass of wall in the case where a fundamental frequency for the wall is not calculated, the value of 5, in equation 1 shall be taken to be the peak of the floor response spectra for the appropriate damping value of the wall.
Applied in plane loads, both horizontal and vertical, shall be defined by a uniform load u where:
P "p " **
(2)
= Applied in plane load in alrection of ground motion wp a = Zero period acceleration from governing floor response spectra m = Mass of wall i
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4.3 Level 1 An lyses 1
This level of analyses def!nes initial conservative procedures that may be used in the reevaluation of the masonry walls.
More rigorous analytical techniques defined in this document may also be used to calculate the responses of the walls.
4.3.1 In-plane stresses:
In-plane shear stresses in the walls and piers due to the wall and equipment loads will be calculated and compared to allowable stresses defined in Section 5 4.3.2 in-plane relative displacement: Masonry walls which are confined on the sides by lateral force resisting member (i.e., knock out panels) shall be considered as in-filled panels and the response of these walls due to imposed in plane relative displacemer ts shall be calculated.
A conservative estimate of the imposed shear stres'; T is:
T " OA (3) h where:
T = Shear stress in masonry panel a = Relative displacement between top and bottom of the wall G = Shear modulus of masonry wall h = Height of wall
4.3.3 Out-of-plane
Out-of plane moments on the walls shall be calculated for the wall and equipment loads. The moments shall be calculated on the basis of considering the wall as a plate spanning in one direction only and simply supported at two ends. The elasti: moment calculated must not impose j
extreme fiber stresses higher than the allowable tensile stress in mortar as i
defined in Section 5.,,
4.4 Level ll Analyses 4.4.1 In-plane relative displacements: An alternative and more accurate approach to the response of in-filled panels than that described in Section wall and surrounding 4.3.2 is to consider the composite action of the masenry frame.
in general, this is a non-linear problem since loads at the panel-frame interface can only be transmitted through compression and the two components are f ree to separate from each other at this interface.
The diagonal tension in the panel due to the composite action of the panel and f rame can be calculated with the use of finite element or ' finite differ-ence approach. This may be done by developing a composite frame-panel mathematical model with proper consideration of non-linear interface condi-tions and then use the model to calculate the diagonal shear in the panel for the prescribed relative displacements.
4.4.2 Out-of-plane
If the elastic out-of-plane moments calculated in Section 4.3.3 cause extreme flher stresses higher than allowabic, then a crack perpendicular to the span of the wall will be assumed and the capacity of the wall to resist the loads through arching action will be calculated as follows:
The loading on the wall will renain as described in Sections a.
2.0 and 4.2 (See Figure Ia). This is conservative since a crack in the wall will render the wall more flexible and hence produce a smaller value of S, in equation I than that based on the elastic stiffness of the plate.
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b.
A crack will be postulated perpendicular to the span of the wall (See Figure Ib) at the point of maximum elastic moment and the wall capacity will be calculated based on the moment P(u)r(u) where:
P(u) = Compressive force developed at cracked boundaries (See Figure Ib).
r(u) = Moment arm between the two compressive forces (See Figure Ib).
Maximum compressive stresses at the cracked sections and shear c.
stresses in the wall shall be in accordance with the acceptance criteria defined in Section 5.
d.
All walls qualified on the basis of section 4.4.2 shall have positive restraint against out-of plane translation at the supports as shown in Figure 2 or its equivalent.
The maximum wall deflection (w) after initiation of cracking e.
(see Figure Ib) shall not exceed i inch.
5.0 Acceptance Criteria 5.1 Masonry Const ruct ion. The American Concrete institute, "Bullding Code Requirements for Concrete Masonry Structures," (ACI 531-79) shall be used as the governing code for all allowables, except as follows:
s Modules of Elasticity E = $00f' but not greater than 3,000,000 psi Modules of Rigidity G = 240f' but not greater than 1,200,000 psi Allowable diagonal tension for hollow unit masonry of 35 psi
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5.2 Steel Construction. All steel construction shall be in accordance with requirements of AISC, " Specification for the Design, Fabrication, and Erection of Structural Steel for Buildings," 1979 edition.
6.0 Acceptance Celteria for Modifications All modifications to the masonry walls shall be in accordance with the acceptance criteria defined In Se; tion 5 0
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