ML20207K099

Forwards Safety Evaluation Re Util Requests for Approval of Use of Increased Cumulative Usage Factor.Pipe Breaks Need Not Be Postulated in Pressurizer Surge Line & in SI Injection Lines.Small Bore Piping Should Be Provided

ML20207K099
Person / Time
Site:	South Texas
Issue date:	12/31/1986
From:	Noonan V Office of Nuclear Reactor Regulation
To:	Goldberg J HOUSTON LIGHTING & POWER CO.
Shared Package
ML20207K105	List: ML20207K099 ML20207K108
References
NUDOCS 8701090275
Download: ML20207K099 (2)

Text

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Docket No.: 50-498 i'

Mr. J. H. Goldberg Group Vice President, Nuclear W

Houston I.ighting & Power Company P.O. Box 1700 Houston, Texas 77001

SUBJECT:

THE SOUTH TEXAS PROJECT (STP) REQUEST FOR APPROVAL ON USE OF INCREASED CUMULATIVE USAGE FACTOR (CUF) i By letters dated March 12, 1986, September 15, 1986, September 17, 1986, October 31, 1986, November 24, 1986, December B, 1986, and De.cember 15, 1986, STP provided technical information to . justify the elimination of postulated intermediate break locations where the CUF is less than 0.4. These letters provide the results of analyses to demonstrate that a small postulated flaw sub. ject to faticue crack growth durino service would remain stable during the lifetime of the olant. STP indicated that by eliminating postulated break locations with a CUF less than 0.4 the number of pipe whip restraints and . jet impingement shields in the pro.fect would be reduced. This action would benefit the South Texas pro. ject because it would reduce the congestion within the facility, the difficulty of performing plant maintenance, and radiation exposure during inservice inspection. This issue is being treated as a deviation from the Standard Peview Plan (SRP) Sectin 3.6.2.

Based en our review the NRC staff concluded in the attached SER that, sub. ject to resolutica of a confirmatory item intermediate pipe breaks identified need not be postulated in the pressurizer surge line and in the SI in.jection lines. The remaining lines evaluated in the attachment are six inches nominal 4 pipe diameter and smaller. The staff has concerns regarding the applicability

of the applicant's assumptions ana analyses for this piping and believes the small bore piping should be provided with pipe break prote

: tion as required by SRP 3.6.2.

, .Please contact the Pro. ject Manager Dr. Prasad Kadambi if you have any further )

l Questions.

Sincerely yours, ncent S. Noonan, h etor 8701090275 PDR PWR Pro. ject Directorate No. 5 ADOOK O A ehojjj{B P D.

Division of PWR I.icensing-w

Enclosure:

As stated Distribution aDocket Files V. Noonan J. Partlow ACD (10) l

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$ .$ WASHINGTON, D. C. 20555 t

3.....p Docket No.: 50-498 Mr. J. H. Goldberg DEC U" Group Vice President, Nuclear Houston I.ighting & Power Company P.O. Box 1700 Houston, Texas 77001

SUBJECT:

THE SOUTH TEXAS PROJECT (STP) RE0 VEST FOR APPROVAI. ON USE OF INCREASED CUMUI.ATIVE USAGE FACTOR (CUF)

By letters dated March 12, 1986, September 15, 1986, September 17, 1986, October 31, 1986, November 24, 1986, December 8, 1986, and December 15, 1986, STP provided technical information to justify the elimination of postulated intermediate break locations where the CUF is less than 0.4. These letters provide the resultc of analyses to demonstrate that a small postulated flaw subject to fatique crack growth during service would remain stable during the lifetime of the plant. STP indicated that by eliminating postulated break locations with a CUF less than 0.4 the number of pipe whip restraints and jet impingement shields in the project would be reduced. This action would benefit the South Texas project because it would reduce the congestion within the facility, the difficulty of performing plant maintenance, and radiation exposure during inservice inspection. This issue is being treated as a deviation from the Standard Review Plan (SRPi Sectin 3.6.7.

Based on our review the NRC staff concluded in the attached SER that, subject to resolution of a confirmatory item intermediate pipe breaks identified need not be postulated in the pressurizer surge line and in the SI injection lines. The remaining lines evaluated in the attachment are six inches nominal pipe diameter and smaller. The staff has concerns regarding the applicability of the applicant's assumptions and analyses for this piping and believes the small bore piping should be provided with pipe break protection as required by SRP 3.6.2.

Please contact the Project Manager Dr. Prasad Kadambi if you have any further  !

questions.  ;

Sin erely yours

~

L. p -

(eht-Sr o n, Director PWR Projec Directo ate No. 5 Division of PWR I.icensing-A

Enclosure:

As stated l