ML19296D657

Forwards Response to IE Bulletin 79-02,Revision 2.Large Pipe Supports That Do Not Meet Criteria Will Be Subj to Rigorous Frame Analysis.Small Pipe Support Typicals Will Be Evaluated for Worst Case Loadings

ML19296D657
Person / Time
Site:	Comanche Peak
Issue date:	01/04/1980
From:	Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
IEB-79-02, IEB-79-2, NUDOCS 8003120706
Download: ML19296D657 (4)

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7ZC TEXAS UTILITIES GENERATING COMIRNY 2(XM BRYAN TOWEM DALLAS. TEXAS 76201 a.,om January 4, 1980

"!YJ:Jf' "'.*Jl:' TXX-3086 Mr. Karl V. Seyfrit, Director U. S. Nuclear Regulatory Commission Region IV RIV 611 Ryan Plaza Dr. , Suite 1000 Docket Nos. 50-445/IE Bulletin 79-02, R.2 Arlington, Texas 76012 50-446/IE Bulletin 79-02, R.2 COMANCHE PEAK STEAM ELECTRIC STATION 1981-83 2300 MW INSTALLATION RESPONSE TO NRC ,

IE BULLETIN 79-02, REVISION 2 FILE NO: 10115

Dear Mr. Seyfrit:

Attached is a report responding to IE Bulletin 79-02, Revision 2, dated November 8, 1979. The report summarizes our previous responses to IE Bulletins 79-02 and 79-02, Rev. I and describes our engineering analysis for IE Bulletin 79-02, Rev. 2.

As stated in the report, support analysis is being made on a continuing basis. We will advise you of any significant developments.

If there are any questions, please advise.

Very truly yours,

[ R/ J. Garyf RJG:df Attachment cc: United States Nuclear Regulatory Commission Office of Inspection and Enforcement Division of Reactor Construction Inspection Washington, D.C. 20555 8003120706

IE Bulletin 79-02, Rev. 2 TXX-3086 Page 2 CURRENT STATUS AND RESPONSE TO IE BULLETIN 79-02, REV. 1 and REV. 2

1. We responded to the original issue to the IE Bulletin on June 22, 1979, CPP No. 1439. This response stated basically the following:

a. ITT Grinnell considered base plate flexibility in original design.

All field modifications would be reviewed by Grinnell's home office.

b. NPSI did not consider base plate flexibility in original base plate design. NPSI would establish an alternate means of analysis that would satisfy the requirements of IE Bulletin 79-02. Changes initiated in the field would be subject to NPSI home office review.

c. G&H does not utilize base plates of pipe supports on this project.

d. A safety factor of five (5) is used in the design of Hilti anchor bolts.

e. All piping loads are transmitted to the building structure. Seismic loads are of such a rare occurrence that they are insignificant relative to anchor bolt fatique failures. Since a safety factor of 5 is applied to the total load, a conservative safety margin exists relative to plant operational loads.

f. A testing program was conducted to determine the required torque values to assure 'he required anchor preload. QC documentation exists to verify oper torquing of anchors. Proper size, type and embedment deptns are verified by QC and documented. Additional Hilti bolt testing is currently underway for several additional size anchor bolts utilized on this project.

2. On July 27, 1979 we submitted our response to Revision No. 1 to NRC Bulletin 79-02. Revision 1 required that we submit a description of our analytical models used to verify that base plate flexibility is taken into consideration in the determination of anchor bolt loads.

Both ITT Grinnell's and NPSI's procedures and equations, which were currently available at this time, were submitted for NRC review.

IE Bulletin 79-02, Rev. 2 TXX-3086 Page 3

3. An ongoing investigation in regard to the optimal method of base plate analysis and other possible ramifications of IE Bulletin 79-02 and its effects on the project continues.

Further developments prior to the issuance of Rev. 2 to the Bulletin are as follows:

a. Since several organizations are involved in component support design, as well as the necessity of installing base plates with unsymetrical anchor bolt patterns, we felt it necessary to develop a consistent means of analyzing base plates and concrete anchor bolt loads.

b. A TI-59 program, developed from the previously submitted ITT Grinnell FUBI program, is in its final stages of certification.

The results achieved through the use of this program, when compared with a certified finite element computer analysis, reflect a high level of conservatism.

All component support base plates which fall under the provi-sions of IE Bulletin 79-02 will be eveluated and certified through the use of this program during final design review.

If a base plate or anchor bolt " fails" this preliminary evaluation due to its conservative nature, the base plate will undergo rigorous computer finite element analysis on a case-by-case basis. We are currently negotiating a contract with an independent consulting firm to perform or make this service available to us. If again the base plate and/or anchor bolts prove inadequate, the component support shall be reworked until satisfactory results can be achieved.

4. On November 13, 1979, Revision 2 to IE Bulletin 79-02 was received for our review and response. This revision primarily raised additional questions relating to the use of concrete anchors embedded in concrete block walls and the use of structural steel shapes instead of base plates.

In regard to this revision, we offer the following input:

a. Concrete block walls are not nor will be utilized for the support of Category I piping systems on this project. We should require no further action on this item.

IE Bulletin 79-02, Rev. 2 TXX-3086 Page 4

b. A considerable number of structural steel shapes are used on this project instead of base plates. These members were considered rigid when calculating base and/or bolt loads and steel size.

The greatest percent of large pipe (2-1/2" and above) utilizing structural shapes consists of tubular steel attached to the structure with Richmond inserts and studs. These supports therefore are exempt from the requirements set forth in IE Bulletin 79-02 at this time.

All large pipe supports that do not meet the above criteria will be subject to rigorous frame analysis, which will assume member flexibility during final design review on a case-by-case basis or justification will be provided for the rigid assumption.

We are currently evaluating our entire small piping and small pipe support analysis method on this project.

Small pipe support typicals will be evaluated for worst case loadings which will consider member flexibility or justification will be provided for the rigid assumption.