ML20041A719
| ML20041A719 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/04/1981 |
| From: | Goldberg J HOUSTON LIGHTING & POWER CO. |
| To: | Jay Collins NRC, NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-SSINS-6820 IEB-79-02, IEB-79-2, ST-HL-AE-747, NUDOCS 8202220436 | |
| Download: ML20041A719 (6) | |
Text
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The Light m m P u y ii""""i.ix"'i"x&>>"
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.""><>is>228-92ii December 4,1981 ST-HL-AE-747 SFN: V-0540 W
03 Mr. John T. Collins g
Regional Administrator, Region IV RbCOQ,g Nuclear Regulatory Commission S
FEs2 8/gg 611 Ryan Plaza Drive, Suite 1000 2
Arlington, TX 76012 is 11 'l
Dear Mr. Collins:
b South Texas Project D
Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 NRC IE Bulletin 79-02: Second Response Revision Houston Lighting & Power Company is revising the response to IE Bulletin No. 79-02 which was transmitted to the NRC April 8, 1980. This revised position, as attached, has been prepared in light of current industry data and testing conducted at STP, and consists of changes and clarifications which are consistent with the guidelines of the Bulletin.
Change bars have been added to the attached report to identify where revisions have been made.
If you have any questions, please contact Mr. Michael E. Powell at (713) 676-8592.
Very truly yours,
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J. H. Goldberg Vice President Nuclear Engineering and Construction PLW/blt Attachment i
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8202220436 811204 i
PDR ADOCK 05000498
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Ilouston Lighting & Power Company ec:
G. W. Oprea,,Jr.
December 4, 1981 J. H.:Goldberg ST-HL-AE-747 J. G.LDewease-SFN: V-0530 D. G. Barker Page 2 C. G. Robertson H. Pyle,.III
-R.
A. Frazar D. R. Beeth J. W. Williams J. W. Briskin
.J.
E. Geiger
-D.
E. Sells (NRC)
H.;S. Phillips (NRC)
J. O. Read (Read-Poland, Inc.)
i M. D. Schwarz (Baker & Botts)
I R. Gordon Gooch (Baker & Botts)
J. R. Newman (Lowenstein, Newman, Reis, & Axelrad) i STP RMS Director, Office of Inspection & Enforcement Nuclear Regulatory Commission Washington, D. C. 20555 R. L. Range /G. W. Muench Charles Bechhoefer, Esquire Central Power & Light Company Chairman, Atomic Safety & Licensing Board P. O. Box 2121.
U. S. Nuclear Regulatory Co'mmission Corpus Christi, Texas 78403 Washington, D. C.
20555
- R. L. Hancock/G. Pokorny Dr. James C. Lamb, III City of Austin 313 Woodhaven Road P. O. Box 1088 Chapel Hill, North Carolina 27514 Austin, Texas 78767 J. B. Poston/A, vonRosenberg Mr. Ernest E. Hill City Public Service Board Lawrence Livermore Laboratory P. O. Box 1771 University of California San Antonio, Texas 78296 P. O. Box 808, L-46 Livermore, California 94550 Brian E. Berwick, Esquire William S. Jordan, III Assistant Attorney General Harmon & Weiss for the State of Texas 1725 I Street, N. W.
P. O. Box 12548 Suite 506 Capitol Station Washinton, D. C.
20006 Austin, Texas 78711 Lanny Sinkin Citizens for Equitable Utilities, Inc.
Citizens Concerned About Nuclear Power c/o Ms. Peggy Buchorn 5106 Casa Oro Route 1, Box 1684 San Antonio, Texas 78233 Brazoria, Texas 77422 Jay Gutierrez, Esquire Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Revision Date 10-29-81
- 5) L.
'Page 1 of 4 Revised Response to NRC IE Bulletin 79-02, Rev. 2 Item'1:
Pipe support base plates are considered flexible elements and analyzed accordingly. Two methods are in use on the STPEGS and include:
(a) The externally applied expansion anchor bolt loads are determined through an appropriate method in which the force generated through the prying effect is calculated by using the equation for A490 bolts given on Page 4-81 of the AISC Manual of Steel Construction (Seventh Edition).
This force is then multiplied by a factor of 1.5 (under no circumstances does this prying force exceed the exter-nally applied bolt load).
The design load is the alge-braic sum of the prying force and the externally applied bolt load.
or (b) The base plates are analyzed with a computer program which uses a finite element, non-linear approach to deter-mine the effects of base plate flexibility on the bolt loads.
Item 2:
Only wedge type anchors are allowed to be used for permanent-plant installations et the South Texas Project.
The minimum factor of safety used between the bolt design load ;nd the bolt ultimate capacity from static load tests is 4.0.
This is consistent with the requirement of the IE Bulletin 79-02 Rev. 2.
The effects of shear-tension inte action, minimum edge distance and bolt spacing are taken into account in the following manner:
a.
Shear-Tension Interaction l
Allowable working loads for combined tension and shear are l
checked to satisfy the following interaction equation:
T b
j applied applied l
1.0 l
T b
allowable allowable T
b Where allowable and allowable are allowa5'e pure tensile l
and shear forces, respectively.
Note that the allowable working loads are not increased for accidental or severe environmental conditions.
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Page 2 of 4 b.
Edge Distance and Bolt. Spacing The minimum concrete edge distance (i.e., the distance to the edge of the concrete from the center-line of the expan-sion bolt) is:
i)
Tension:
Edge distance = 6D or 6" Whichever is greater
- 11) Shear:
Edge distance = 10D or 6" Whichever is greater Where:
D = nominal diameter of anchor, in.
If the bolt is under combined shear and tension, the shear edge distance governs.
The minimum spacing between two expansion bolts is normally 12D.
However, if the embedment depth is less than 6D, the minimum spacing is twice the embedment lcngth. Closer bolt spacing may be permitted, but the allowable bolt capacity is reduced on a straight line basis down to 50% at a spacing equal to b the minimum spacing.
When the ratio Allowable Ultimate Load / Actual Load is equal to 10.0 or more, the expansion anchor is considered " lightly loaded." When expansion anchors are " lightly loaded," mini-mum embedment of 4.5D is permitted.
Item 3:
Safety-related piping systems are analyzed for dynamic loads such l
as seismic loadings, water hanner, steam hammer, safety relief valve discharge, etc.
Equivalent static pipe si;pnort design loads are then. determined for the above -load conditions as applicable.
In accordance with a test program for wedge and sleeve type anchor bolts (Reference 3), it has been concluded that the dynamic load capacities of such expansion bolts are about the same as their corresponding static load capacities. Therefore a minimum factor l
of safety of 4.0, given in the response to Question No. 2 above, has been utilized in the design of wedge type expansion anchor bolts for the above loads.
l.
Item 4: A technical reference document (Reference 4) has been established to consider various design requirements.
Additional prcloading j
due to the presence of cyclic loads is not required.
No additional torque / tension has to be provided other than that which is required l
for setting the bol t.
Each bolt will have a special marking which specifies its length. This special marking is permanently stamped i
on the top end of the bolt so that it can be read when the bolt is in place.
r:
Page 3 of 4
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Note that no shell or sleeve type anchor bolts are used for permanent installations on STPEGS.
A static expansion anchor bolt testing prcgram was conducted in accordance with Reference No. 4 to confirm manufacturers publish-ed ultimate capacity values or to establish new ultimate capacity values.
Minimum torque / turn of nut values were established and reduction factors were selected for wedge type anchors installed in grout placements. The minimum torque / turn of nut value, ensure anchor bolt "preload" is equal to or greater than the design load.
Pre-viously installed expansion anchor bolts that support Safety Related piping systems will be checked for mir. mum torque require-ments.
Item 5: No expansion anchors bolts will be used in concrete block (masonry) walls for attaching pipe supports in Seismic Category I systems.
Item 6: Structural steel shapes will not be used instead of base plates when expansion anchors are usedwith pipe supports in Seismic Cate-gory I systems as defined by Regulatory Guide 1.29, Revision 1, dated August, 1973.
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Page 4 of 4
References:
1.
Code Requirements for Nuclear Safety-Related Concrete Structures (ACI 349-80), Reported by ACI Committee 349; Appendix B.
2.
Standard for Testing Anchors in Concrete, Expansion Anchor Manufacturers Institute, Inc. New York.
3.
Drilled-In Expansion Bolts Under Static And Alternating Load, a report prepared for Hanford Engineering Development Laboratory, Richland, Washington by Bechtel Power Corporation, San Francisco California, Report No. BR-5853-C-4, January 1975.
4.
Design, Installation, Testing & Inspection of Concrete Expansion Anchor Bolts, Technical Reference Document No. 5A0195Q010, Brown & Root, Inc.
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