ML19275A094

Forwards Response to IE Bulletin 79-02 Re Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts.Only cast-in-place Embed Plates Used for Pipe Supports at Facility.Design Methods Outlined for concrete-type Plates

ML19275A094
Person / Time
Site:	Vogtle
Issue date:	07/06/1979
From:	Staffa R GEORGIA POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 7908310027
Download: ML19275A094 (4)

Text

Georgia Power Comp. i > f 230 Peachtree Street )

Post Off.ce Box 454s Atlanta Georgia 30313 ijpg p:*

• Telephone 404 522-6060  ; '(, _

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(""'gia Power Power Supply Engineering Ed Services ^h.02 July 6, 1979 United States Nuclear Regulatory Comission

REFERENCE:

Office of Inspection and Enforcement Region II - Suite 3100 RII: JP0 50-424 101 Marietta Street 50-425 Atlanta, Georgia 30303 ATTENTION: Mr. James P. O'Reilly Gentlemen:

Enclosed please find "A Report on Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts" which is submitted in response to I.E. Bulletin 79-02.

At present Georgia Power Company is using only cast-in-place embed plates for pipe supports, and the pipe support base plates with concrete expansion anchors have not been used at Plant Vcgtle. The attached report summarizes the design methods to be followed in case this option is required in future base plate designs.

Should you have any questions, please contact my office.

Very truly y6urs,

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. W. Staffa nag ofQudlityAssurance CWH/aaw xc: U. S. Nuclear Regulatory Comission Office of Inspection and E-forcement Division of Reactor Construction Inspection Washington, D.C. 20555 M. D. Hunt - Region II U. S. N. R. C.

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MO/W Or FACIAL COPY

A REPORT ON PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS (In response to: NRC IE Bulletin No. 79-02, dated March 8, 1979)

I. INTRODUCTION ,

This report is in response to NRC IE Bulletin 79-02, dated March 8, 1979, requiring all licensees and permit holders for nucl_ ear power plants to review the design and installation proceBures 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.

At present the Vogtle Project has not used pipe support base plates with concrete expansion anchors and therefore our response summarizes the design. methods to be followed in case this option is used in future base plate designs using concrete expansion anchors.

II. RESPONSE TO ACTION ITEMS

1. Verify that pipe support base plate flexibility was accounted for in the calculation of anchor bolt loads.

In lieu of supporting analysis justifying the assumption of rigidity, the base plates should be considered flexible if the unstiffened distance between the member welded to

• the plate and the edge of the base plate is greater than twice the thickness of the plate. If the base plate is determined to be flexible, then recalculate the bolt loads using an appropriate analysis which will account for the effects of shear-tension interaction, minimum edge distance and proper bolt spacing. This is to be done prior to testing of anchor bolts. These calculated bolt loads are referred to hereafter as the bolt design loads.

RESPONSE: All pipe support base plates using expansion anchor bolts will >e analyzed to account for plate flexibility, shear-tension interaction, minimum edge distance and proper bolt spacing.

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 manuf acturer 's) which simulate the actual conditions of installation (i.e., type of concrete and its strength properties):

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 will be used.

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3. Describe the design requirements if applicable for f anchor bolts to withstand cyclic loads (e.g., seismic loads and high cycle operating loads) .

RESPONSE: The design of piping systems considers Headweight, thermal, cyclic vibration, seismic loads, and dynamic loads in the generation of the static equivalent pipe support design loads. To the extent that these loads include cyclic considerations, these effects will be included in the design of the hangers, base plates and anchorages.

The safety factors to be used for concrete expansion anchors, installed on supports for safety related piping systems, will not be increased for loads which are cyclic in nature.

The use of the same safety factor for cyclic and static loads is based on the FFTF Tests *. The test results indicate:

a. The expansion anchors successfully withstood two million cycles of long term fatique loading at a maximum intensity of 0.20 of the static ultimate capacity. When the maximum load intensity was steadily increased beyond the aforementioned 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, was about the same as their corresponding static ultimate capacitites.

4. Verify from existing QC documentation that design requirements have been met for each anchor bolt in the following areas:

Cyclic loads have been considered (e.g., anchor (a) bolt 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).

• Dri.lled - In Expansion Bolts Under Static and Alternating Loads, Report No. BR-5853-C-4 by Bechtel Power Corporation, January 1975.

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l If sufficient documentation does not exist, then ! initiate a testing prog:am that will assure that minimum design requirenents have been met with respect to sub-items (a) and (b) above. A sampling technique is acceptable. One acceptable technique is to rendomly select and te=t one anchor bolt in each base plat'c (i.e., some supports may have more than one base plate). The test should provide verification of sub-items (a) and '(b) above. If>the test fails, all other bolts on the base'platt should be similarly tested. In any event, the test program should assure that each Seismic Category 1 system will" perform its intended . f dnetion. -

RESPONSE:- A specification will be written defining ,

procedures for installation, verification and testing c efE concrete e>:pansion anchors along with the acceptan. c criteria. These procedures will require nil expansion anchors to be verified for location, elevatior., spacing and edge distance as shown on design drawings, type of anchor used, embed =ent, length and' projection _of anchors, washers, age of concrete, anchor bolt diameter and anchor bolt length e Alsos, expansion anchors..will be tested for preload using a sampling techniget. The proper documentation, indicating tha. location of expansion-anchor and group represented, methn6 of test,(terque or tension), test results, type of failure when epplicable, date of test along with name and signaturn of 't.he inspector, sill be maintained atsthe jobsite.

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