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THE CINCINNATI GAS & ELECTRIC COMPANY sIK~ 7CINCIN N ATI.OHto 45201

July 6, 1979

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U.S. Regulatory CommissionOffice of Inspection and EnforcementRegion III7999 Roosevelt RoadGlen Ellyn, Illinois 60137

ATTN: Mr. James G. KepplerRegional Director

RE: WM. H. ZIMMER NUCLEAR POWER STATION - UNIT 1IE BULLETIN 79-02, PIPE SUPPORT BASE PLATE DESIGNSUSING CONCRETE EXPANSION ANCHOR BOLTS, DOCKET 50-358W.0. 57300, JOB E-5590, ITEN 400

Gentlemen:

The attached documents are being furnished in response to IE Bulletii.s79-02 and 79-02 Rev. 1.

Included are the following:

Attachment (1) Response to IE Bulletins 79-02 and 79-02Rev. 1.

Attachment (2) Evaluation of analysis procedures for thedesign of expansion plates in concrete,dated May 31, 1979.

We believe this information provides a complete response to NRC IE Bulletins79-02 and 79-02 Rev. 1.

Very truly yours,THE CINCINNATI GAS & ELECTRIC COMPANY

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E.A. BORGMANN, SEN E PRESIDENT

JCH/kjdENCLOSUREcc: NRC Office of Inspection and Enforcement

Division of Reactor Inspection ProgramsWashington, D.C. 20555

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2012 2',3R.F. Scheibel J.D. Flynn W.W. Schwiers s

I84S. Rurka J.R. Schott K.K. ChitkaraW.D. Wa ire H.C. Brinkmann General File

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S.G. Sa ay H.E. Crail g

*. . ATTACHMENT 1

RESPONSE TO IE BULLETIN NO. 79-02 REV. 1,

ZIMMER - UNIT 1

CINCINNATI GAS & ELECTRIC COMPANY

1. The pipe support baseplates for Zimmer Unit 1 have been designed

based upon rigid plate theory. Cincinnati Gas & Electric Company

has evaluated the rigid plate analysis procedure compared with flexi-

ble plate analysis procedure, and has concluded that the design of

expansion anchored plate assemlbies 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, "Evauluation of Analysis Pro-

cedures for the Design of Expansion Anchored Plates in Concrete," dated

May 31, 1979, that, when the flexibility of the expansion anchored base-

plate assembly, in conjunction with the load versus displacement behavior

of the expansion anchor, is accounted for in a finite element. solution,

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 Zimer Unit 1 for various expansion anchor types, embedment depths, pre-

load levels and applied load patterns which may typically be encountered in

such installations. It is, therefore, Cincinnati Gas & Electric Company's

opinion that adequate margin exists in the present design of expansion an-

chored plate assemblies to accomodate the effect of the flexibility of

the baseplate assemblies as required by the Nuclear Regulatory Comission.

The load-displacement curves illustrated in the attached report were ob-

tained from field tests at several nuclear stations currently under con-

struction, and are judged to be conservative. Cincinnati Gas & Electric

Company will participate in a comprehensive static testing program for 012~N '62'

concrete expansion anchors under the direction of an Independent Testing

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Laboratory to verify these load-displacement curves..

Also, the test program will include testing to failure flexible expansion

anchored plate assemblies designed using rigid plate theory, and demonstrat-

ing that the failure load equals or exceeds four (4) times the design load.

The static test program to verify the load-displacememt curves and ultimate

loads will encompass the following combination of variables:

a) bransion anchor types

1) Wedge type anchors

2) Self-drilling type ancP. ors

b) Anchor diameter

1) 1/4"

2) 3/3"

3) 1/2"

4) 5/8"

5) 3/4"

6) 1"

c) Embedment depth - 4-1/2 anchor diameters

d) Embedment material

1) Concrete-F{=3500psiand5500 psi

2) Masonry mortar - ASTM 270, Type M and Type N

In addition, this testing program will also assess the long term preload

relaxation characteristics of wedge and self-drilling type anchors.

The results of the static test program will be available for review by the

Nuclear Regulatory Commission upon completion.,

2. Cincinnati Gas & Electric Company has verified that concrete expansion

anchor bolts have been designed using a minimum factor safety of 4.0 be-

tween the bolt design load and the bolt ultimate capacity detennined

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from manufacturer's static data for wedge and self-drilling type anchors..

91is factor of safety has been traditionally recommended by manufacturers

of both wedge and self-drilling type expansion anchors for static loads.

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 aralysis, 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 that data for

wedge and self-drilling type anchors. Cincinnati Gas & Electric Company

will participate in a comprehensive dynamic test program under the di-

rection of an Independent Testing Laboratory to verify the dynamic be-

havior of wedge and self-drilling type expansion anchors. These tests

will be perfonned on rigid plate expansion anchored assemblies under the

following dynamic conditions:

a) Pipe transient cyclic loads

b) OBE seismic loads

The results of the dynamic test program will be available for review by

the Nuclear Regulatory Comission upon completion.

4. A mixture of wedge and self-drilling type concrete expansion anchors have

been used in safety related areas at Zimer Unit 1. The minimum embedment

length for wedge type anchors is 4-1/2 anchor diameters. Self-drilling

expansion anchors were used only on a limited basis in safety related

areas prior to 1976. All concrete expansion anchors were specified to be

installed at Zimer Unit 1 in accordance with manufacturer's recomendations.

Cincinnati Gas & Electric Company will inspect wedge and self-drilling, 'r, o

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type expansion anchors supporting safety related piping in which the cal-.

culated factor of safety ( ultimate anchor capacity divided by the cal-

culated applied load ) is less than or equal to 10, at Zinner, Unit 1,

to assure confonnance to manufacturer's installation recommendations.

Wedge type expansion anchors will be inspected to verify the following

items:

a) Minimum test torque level

b) Minimum embedment length

c) Expansion anchor size

Expansion anchors which do not meet the required test torque value will be

retorqued to the installation value and n! inspected within seven days to

assure that relaxation has not exceeded the required test torque value.

Expansion anchors which do not have the correct embedment length or size

will be reanalyzed and, if inadequate to support the design loads, will be

replaced, or the expansion anchored plate assembly modified accordingly to

support the design loads.

Manufacturers of self-drilling concrete expansion anchors typically have

not specified initial installation torque values. The torquing of a self-

drilling anchor does not seat the anchor in the concrete hole, and, thereby,

minimize anchor displacement as in the case of wedge and sleeve type anchors.

Cincinnati Gas & Electric Company, however, will participate in a test pro-

gram for self-drilling type expansion anchors under the direction of an In-

dependent Testing Laboratory to determine appropriate installation and test

torque levels to assure that the preload in the self-drilling

expansion anchors is greater than or equal to the design loads.

A random sample of self-drilling expansion anchored assemblies

supporting safety related piping will be inspected by applying

the test torque to the individual anchors. The self-drilling 2 012 2 A 'expansion anchors will be inspected subsequent to the application

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of the test torque to assure that the shell of the self-drilling expansion anchor is no? in contact with the back of

the expansion anchor baseplate. Self-drilling expansion anchors

which are in contact with the back of the expansion anchor base-

. plate will either be replaced with a wedge type anchor, or the

expansion anchored plate assembly modified accordingly to

support the design. loads.

Future expansion anchor installations at Zimmer Unit 1 will consist of

wedge type only, with an embedment length equal to 4 anchor diameters.

These anchors will be installed in accordance with approved QA/QC pro-

cedures, and the design load for these anchors will be less that the

specified anchor preload.

The results of Cincinnati Gas & Electric Company's verificaton of

existing expansion anchor installations at Zimer Unit 1 will be avail-

able for review by the Nuclear Regulatory Commission upon completion.

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**Attachment (2)

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EVALUATION OF ANALYSIS PROCEDURES TOR THE/

DESIGN OF EXPANSION ANCHORED PLATES IN CONCRETE

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PREPARED BY: OM

REVIEWED BY: M d%

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APPROVED BY: ( ./q/- o ,, -' '

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May 31, 1979'

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7.DUPLICATE DOCUMENT

2 0 'i 2 q c: jSargent & L .-Entire document previously

Chicago, eintered into system under:

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4 No. of pages: fyl._