ML20236F754
| ML20236F754 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/27/1987 |
| From: | Rice P GEORGIA POWER CO. |
| To: | NRC |
| References | |
| GN-1385, IEB-79-02, IEB-79-14, IEB-79-2, NUDOCS 8708040019 | |
| Download: ML20236F754 (8) | |
Text
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Georgia Power Company Post Office Box 282 Waynesboro, Georgia 30830 '
Telephone 404 554-9961, Extension 3413 i
404 724 8114, Extension 34n 1
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. vogtte Project ce soumem electrx; sciem f
July 27, 1987-United States Nuclear Regulatory Commission Document Control Room File:
X7BC24 Washington, D. C.
20555-Log:
GN-1385
Reference:
Vogtle Electric Generating Plant - Unit 1; 50-424; IE Bulletin 79-02; Letter GN-1273 dated 12/31/86 In our correspondence GN-1273 referenced above, Georgia Power Company (GPC) notified the USNRC that it had completed its Final Design Verification Program for' Safety-Related Piping. systems for Unit 1
. of. the Vogtle Electric Generating Plant (VEGP).
This program was designed to~ address the requirements of USNRC IE Bulletin 79-14, but also included provisions to verify compliance. with certain requirements of IE Bulletin 79-02.
The Final Design Veri fication -
Program was completed during the construction phase and consisted of engineering / construction wa1kdowns of all safety-related piping.-
syrtems. Base plate and anchor bolt location, minimum edge distance,.
ana bolt spacing were verified during the walkdowns for the limited number of safety-related pipe support base plates in Unit I which utilize concrete expansion anchors.
The attached report is. a summary, by item, of the methods utilized by GPC to address the requirements of IE Bulletin 79-02, Revision 2.
j This report demonstrates that Georgia Power Company has effectively ensured compliance with IE Bulletin 79-02 for Unit 1 of VEGP.
A j
similar program ar, that used for Unit I has - been initiated for Unit 2.
This correspondence contains no proprietary information and may be placed in the USNRC Public Document Room, l
P. D. Rice CWH/PDR/wkl.
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USNRC - Region II Suite 2900 101 Marietta Street, NW
. Atlanta, Georgia 30323 H. G. Baker D. R.' Altman L. T. Gucwa J. P. O'Reilly
.J. A. Bailey C. W. Hayes R. E. Conway G. Bockhold R. W. McManus R. H..Pinson
-C. E. Belflower Sr.. Resident (NRC)
E. D. Groover J. F. D'Amico C.-C.~ Garrett (0PC) 8708040019 0
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Rice states that he is the Vogtle Project Director and is authorized co execute this oath on behalf of Georgia Power Company and that to the best of his knowledge and belief the fa. cts set forth in this letter are true.
l GPC:
Sworn to and subscribed before me this 48 day of
, 1987.
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A REPORT ON PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS (In. response to:
NRC I.E.
Bulletin No.
79-02, Revision 2 dated November 8, 1979)'
I.
INTRODUCTION
)
This : report is in. response to NRC I.E.
Bulletin 79-02, Revision 2 dated November 8, 1979, requiring all licensees and permit holders i
-for nuclear power plants to review the. design and installation procedures for concrete expansion anchor bolts. used in. pipe support base. plates in ' systems defined. as Seismic Category I by the - NRC Regulatory. Guide 1.29,
" Seismic Design Classification", Revision 1, dated August 1973 or by the applicable SAR.
II.
RESPONSE'TO ACTION ITEMS 1.
Verify that pipe. support. base plate flexibility was - accounted
-for in the. calculation of anchor bolt loads.. A. description.
j of the analytical model.used to ver.ify that pipe support base
]
plate flexibility is accounted. for in.the calculation of anchor i
bolt loads is to be submitted with your response to the Bulletin.
RESPONSE: All pipe support base plates using expansion anchor:
bolts were. analyzed to account for plate flexibility, shear-tension interaction, minimum edge distance and proper bolt spacing.
The base plate flexibility 'is typically' accounted for in the calculations :of anchor bolt loads by considering that the. resul tant of-.the stress in concrete due to the moment acts at the compression flange of the' attached beam or column.
(See Figure 1)
Alternatively, a finite element program' (ME-035 Base
.I Plate) is used to analyze pipe support base plates.
This program performs geometry calculations to generate -
the finite element model, creates data' sets for output report tables. and the determination of the deformed and/or undeformed geometry configuration.
By modeling the base ' plate as an assemblage 'of finite elements, plate flexibility is automatically accounted for.
)
2.
Verify that the concrete expansion anchor bolts have the following
- minimum factor of safety between. the ' bolt design load and the bolt ultimate capacity determined from static load tests (e.g.,-
anchor. bolt manufacturer's) which simulate the actual conditions J
of installation (i.e.,
type of concrete and :its ' ' strength properties) i x
1
1 i
a.
Four - For wedge and sleeve type anchor bolts, b.
Five - For shell type anchor bolts.
RESPONSE
Factors of safety (i.e.,
ratio of bolt ultimate capacity to design load) of four for wedge type - and five for shell type anchor bolts were used.
3.
Describe the design requirements if applicable for anchor bolts to withstand cyclic loads (e.g.,
seismic loads and high cycle operating loads).
RESPONSE
The design of piping systems considers deadweight, thermal, cyclic vibration, seismic loads, and dynamic loads in the generation of the static equivalent j
pipe support design loads.
To the extent that these i
loads include cyclic considerations, these effects I
were included in the design of the hangers, base plates and anchorages.
The safety factors to be ' used for concrete expansion i
. anchors, installed on supports for safety-related piping systems, were not increased for loads which are cyclic in nature.
l The use of the same safety factor for cyclic and static loads is based on the FFTF Tests *.
The test results indicate:
i a.
The expansion anchors successfully withstood two million cycles of long term fatigue loading at a maximum intensity of 0.20 of the static ultimate capacity.
When the maximum load intensity was steadily increased beyond this value and cycled for 2,000 times at each load step, the observed failure load was about the same as the static ultimate capacity.
b.
The dynamic load capacity of the expansion anchors, under simulated seismic loading 3 was about the same as their corresponding static ultimate capacities.
- Drilled In Expansion Bolts Under Static and Alternating Loads, Report No. BR-5853-C-4 by Bechtel j
Power Corporation, January 1975.
4.
Verify from existing QC documentation that design requirements have been met for each anchor bolt in the following areas.
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a.
Cyclic loads have been considered. (e.g., anchor i
bol t preload is equal to or greater than bolt design load).
.In the case of the shell type,.
assure that it is not in' contact, with the back of the support plate prior to preload' testing, b.
Specified design size and type-is correctly installed (e.g., proper embedment depth).
a 4
If sufficient documentation does not exist, then initiate a testing program that will assure that minimum design requirements have been met with respect to sub-items (a) and (b). above.
A sampling technique is acceptable.
The test program should assure that each Seismic Category I system will perform its intended function.
RESPONSE
VEGP Construction ' Specification X2AP01, Section C9.7 3 provides procedures for installation, verification and testing of concrete _ expansion anchors along. with the acceptance cri teria.
Expansion anchors. were tested for preload using. a sampling technique.
Installation criteria such as' minimum edge distance, bolt spacing, bolt size and type, embedment depth, preload testing, use of proper hardware, bolt location, and age of concrete were verified during quality control inspections and documented in inspection records.
Base plate and anchor bolt location, minimum edge distance, and bol t spacing was also checked during engineering walkdowns as part of the Unit 1 Final Design Verification Program.
A concrete expansion anchor acquires some amount of preload as a result of the torquing at installation.
The torque values shown in -VEGP Construction Specification X2AP01, C9.7 Table 1 are in accordance with manufacturer's recommendations and are the same or higher than the minimum torque values specified in Bechtel Design Guide C2.40 and in Toole V of:
'q Technical Report No.
1372 published by International 4
Conference of Building Officials, in - February 1984.
Thus, the project specified torque values _ are in 1
accordance with standard torque values used throughout the industry and will provide sufficient preload in the anchor to insure that the anchor has 'been properly installed.
The I.E.
Bulletin 79-02 issued on March 8,
- 1979, required in item 4 that "the anchor bolt preload be equal to or greater than bolt design load."
This was required to addre.ss a concern of'possible ' reduction in the. ultimate capacity of an anchor under cyclic' loading.
It is recognized that the anchor preload partially dissipates over a
period of time.-
(relaxation).
e
l.j Revision 2 of the bulletin issued on November 8, 1979, clarified this requirement as follows:
"Those licensees that have not verified anchor bolt preload are not required to go back and establish preload.
However, additional information should be submitted which demonstrates the effects of preload on the anchor bolt ultimate capacity under dynamic loading."
Thus, it is not necessary to establish the preload in a concrete expansion anchor based on the additional information available in the following references:
Summary report; generic response to USNRC I.E.
Bulletin 79-02, base plate / concrete expansion anchor bolts, dated August 30, 1979.
Summary report; static, dynamic and relaxation testing of expansion anchors in response to NRC I.E.Bulletin 79-02, dated July 20, 1981, submitted to NRC by Commonwealth Edison.
"The Effects of Preload upon the Strength of Typical Concrete Expansion Anchors under Dynamic
- Loading, M.R.
Lindquist, presented at the ACI Annual Convention, Phoenix, Arizona, March 1984.
These reports have demonstrated that the ultimate static and dynamic load capacities of cont-ete expansion anchor bolts are not affected by the magnitude of the preload.
Even an anchor bolt with j
no preload has no reduction in its ultimate capacity, provided that the anchor is properly installed.
Accordingly, since the magnitude of the existing preload is not important to proper anchor performance, there is no need to determine preload at installation.
Proper installation of a concrete expansion anchor is important for adequate performance with no reduction in its load carrying capacities.
VEGP Construction
)
specification X2AP01, C9.7 summarizes the installation requirements for concrete expansion anchors, gives the inspection and testing requirements for proper installation of the concrete expansion anchors, and requires the documentation of the specified information and testing.
These specification requirements in conjunction with quality control verification ensure the adequate performance of concrete expansion anchors, thus satisfying the intent of the I.E.Bulletin 79-02.
5.
Determine the extent that expansion anchor bolts were used in concrete block (masonry) walls to attach piping supports in Seismic Category 1 systems (or safety-related. systems as defined by Revision 1 of I.E. Bulletin No. 79-02).
a
RESPONSE
Concrete block walls have not been used to support piping in Seismic Category 1 systems at VEGP.
6.
Determine the extent that pipe supports with expansion anchor bolts used structural steel shapes instead of base plates.
The systems and lines reviewed must be consistent with the criteria of I.E. Bulletin No. 79-02, Revision 1.
RESPONSE
To date, VEGP has. not used structural steel members attached directly to the concrete by expansion anchor bnits to support Seismic Category 1 piping.
In case this option is used, the same design philosophy as i
outlined for expansion anchors with base plates will i
be used.
l 7.
Bulletin Item 7 is not applicable to VEGP.
8.
Maintain documentation of any sampling insoection of anchor bolts required by item 4 on site and available for NRC inspection.
All holders of construction permits for power reactor facilities are' requested to complete items 5 and 6 for installed pipe supports within 60 days of date of issuance of Revision No.
2.
For pipe supports which have not yet been ' installed, document your action to assure that items 1 through 6 will be satisfied.
Maintain documentation of these actions on site available for NRC inspection.
RESPONSE: Actions required in Item 8 have been accomplished as described in the response to item 4.
These actions, including documentation, have al ready been reviewed and accepted by USNRC Region II inspectors.
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LOAD PATTERN IN BASE PLATE /EXP ANSION 80 LTS
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