ML19207B429

Responds to IE Bulletin 79-02, Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts. Forwards Evaluation of Analysis Procedures for Design of Expansion Anchored Plates in Concrete by Sargent & Lundy Engineers

ML19207B429
Person / Time
Site:	Marble Hill
Issue date:	07/03/1979
From:	Coughlin J PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19207B430	List: ML19207B429 ML19207B432
References
NUDOCS 7908290304
Download: ML19207B429 (3)

Text

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PUBLIC SERVICE INDIANA auly 3,1979 James CougNin Vice President -

Nuclear Mr. James G. Keppler, Director Docket Nos.:

U. S. Nuclear Regulatory Commission STN 50-546 Region III STN 50-547 799 Roosevelt Road Glen Ellyn, Illinois 60137 Construction Permit Nos.:

CPPR-170 CPPR-171 Marble Hill Nuclear Generating Station, Units 1 & 2 I & E Bulletin No. 79-02

Dear Mr. Keppler:

This is in response to I & E Bulletin No. 79-02, which is due July 7,1979. The numbering corresponds to the numbers given in the subject bulletin.

1. The pipe support baseplates for Marble Hill Units 1 and 2 have been designed based upon rigid plate theory. Public Service Indiana has evaluated the rigid plate analysis procedure compared with a flexible plate analysis procedure, and has concluded that the design of expansion anchored plate assemblies using rigid plate theory provides factors of safety ranging from a minimum of 4.0 to a maximum of 8.7 against manufacturer's recommended ultimate failure loads. It has been shown in the attached report, entitled, " Evaluation of Analysis Procedures for the Design of Expansion Anchored Plates in Concrete," dated May 31,1979, that, when the flexibility of the expansion anchored baseplate assembly, in conjunction with the load versus displacement behavior of the expansion a chor, is accounted for in a finite element solutic,n, the " prying action" forces are largely relieved, and the flexible plate solution approaches the rigid plate solution. This has been concluded for the typical expansion anchor assemblies used to support mechanical components for Marble Hill Units 1 and 2 for various preload levels and applied load patterns which may typically be encountered in such installations. It is, therefore, Public Service Indiana's opinion that adequate margin exists in the present design of expansion anchored plate assemblies to accommodate the effect of the flexibility of the baseplate assemblies as required by the Nuclear Regulatory Commission.

The load-displacement curves illustrated in the attached report were obtained from field tests at several nuclear stations currently under construction, and are judged to be conservative. Public Service Indiaaa will participate in a comprehensive static testing program for concrete expansion anchors under the direction of an Independent Testing Laboratory to verify these load-displace-ment curves.

7908290 W @g, 4M -W 1000 East Main Street, Plainfield, Indiana 46168 8 317. 839.9611 O63 10?

Mr. James G. Keppler, Director July 3,1979 Also, the test program will include testing to failure, flexible expansion

- anchored plate assemblies designed using rigid plate theory, and demonstrating that the failure load equals or exceeds four times the design load.

The static test program to verify the load-displacement curves and ultimate loads will encompass the following combination of variables:

a) Wedge type expansion anchors b) Anchor diameter

1) 1/4"

2) 3/8"

3) 1/2"

4) 5/8"

5) 3/4"

6) 1" c) Embedment depth - 3 anchor diameters d) Embedment material

1) Concrete - f'c = 3500 psi and 5500 psi

2) Masonry mortar - ASTM 270, Type M In addition, this testing program will also assess the long term preload relax-ation characteristics of wedge type anchors.

The results of the static test program will be documented End be avaiable for Nuclear Regulatory Commission inspection upon completica.

2. Public Service Indiana has verified that concrete expansion anchor bolts have been designed using a minimum factor of safety of 4.0 between the bolt design load and the bolt ultimate capacity determined from manufacturer's static data for wedge type. anchors.

3. The dynamic / cyclic loads for which the pipe support baseplates have been -

designed were obtained from either a response spectrum or time history method of analysis, and, therefore, properly accounts for any dynamic load factors. The concrete expansion anchor design allowables were based upon maintaining a minimum factor of safety of 4.0 between the dynamic / cyclic design loads, corresponding to an OBE event, and the bolt ultimate capacity, as determined from manufacturer's static load test data for wedge type r.nchors. Public Service Indiana will participate in a comprehensive dynamic test program under the direction of an Independent Testing Laboratory tc verify the dynamic behavior of wedge type expansion anchors. These tests will be performed on rigid plate expansion anchored assemblies under the following dynamic conditions:

853 193 1@^ ~b -

Mr. James G. Keppler, Director July 3,1979 ,

a) Pipe transient cyclic loads b) OBE seismic loads The reruits of the dynamic test program will be documented and be available for Nuclear Regulatory Commission upon con 'on.

4. Wedge type expansion anchors with an embedmsnt depth equal to S anchor diameters will be used exclusively in safety related areas for lWarble Hill Units 1 and 2. Note that the attached generic Sargent & Lundy analysis includes a shell type anchor (self drillingi, although these will not be used in safety related applications at Marble Hill. All concrete expansion anchors will be installed in accordance with approved QA/QC procedures. These procedures require, as e minimum, verification of the following items:

a) Installation torque b) Test torque (a measure of expansion anchor preload relaxation) c) Embedment depth d) Anchor size The design of the concrete expansion anchors for Marble Hill Units 1 and 2 has assured that the expansion anchor bolt preload is greater than or equal to the design load.

Public Service Indiana will verify that the QA/QC documentation is available for the concrete expansion anchors installed at Marble Hill Units 1 and 2.

Since\ y,

\ l-

'\ ' 3. Coughlin  %

Vice President-Nuct r SJB:bbd cc: U. S. Nuclear Regulatory Commission Office of Inspection & Enforcement Division of Reactor Construction Inspection Washington, D.C. 20555 Mr. Edward R. Schweibinz U. S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 853 194