ML20147D487

the Plan to Provide a Guard Pipe Around Steam Line W/In Each Steam Generator Enclosure to Limit Possible Steam Line Size Break & Location Is Acceptable.More Info Required to Accept Entire Submittal

ML20147D487
Person / Time
Site:	Catawba
Issue date:	10/06/1978
From:	Varga S Office of Nuclear Reactor Regulation
To:	Dail L DUKE POWER CO.
References
NUDOCS 7810140086
Download: ML20147D487 (3)

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UNITED STATES

, NUCLEAR REGULATORY COMMISSION

{. $ WASHINGTON. D. C. 205$5

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pl 007 6 1978 Decket Nos: 50-413 l 50-414 Mr. L. C. Dail Vice President Design Engineering Department i Duke Power Ccmpany P. O. Box 33189 l Charlotte, North Carolina 28242 l

SUBJECT:

STEAM GEEM'IVR COMPARThEVr ANALYSIS - CATANBA NUCLEAR STATION  !

We have reviewed the information provided with your letter of March 13, 1978 in response to ours of December 2,1977. Your approach to the design of the steam generator enclosures at Catawba of providing a guard pipe around the steam line within each steam generator enclosure to limit the possible steam line break size and location to a 3.05 ft2 ,

break at the top of the steam generator is the same as that for the htGuire plants, and is generally acceptable. However, before we can find all aspects of vour submittal acceptable, we regttire ft'.rther information regarding the following.  !

1. Your analysis of subcampartment pressures is identical to entresponding portions of the analysis used in McGuire. However, the htGuire '

analysis also included a nodalization sensitivity study, and that plant's manmtri calculated differential pressure for the steam generator enclosure subcompartment design of 13.75 psi was determined from a two-node model. The Catawba analysis refers to a nodali:ation study, but the steam generator enclosure peak differential pressure is shown as 12.5 psi (for the nine-node case). Please explain this apparent discrepancy, or use 13.75 psi as the basis for the design of the steam generator enclosure.

It should be noted that on Catawba you have agreed to apply a 40% margin to the mwh= calculated pressures for use in sub-compartment design. Therefore a design pressure differential of >

1.4 X 13.75 = 39.25 psi would appear appropriate for the Catawba  ;

steam generator enclosures. ,

@ l & N BG.

L

I Mr. L. C. Dail OCT 6 1978

2. To be consistent with our position regarding subcompartment

, analysis margins, the maximum asymetric pressure acting on the ,

steme generator should also have a 40% margin applied for use in design of the supports. Please confirm your agreement with this position.

3. With regard to inservice inspection for the main steam pipe welds enclosed by the guard pipe, you state that " inspection ports must be provided for these welds." We integret this statement as a comit:ent to provide such inspection upenings.

Please verify this interpretation.

4. Certain features of your inservice inspection plan are not considered accept.ble at this time. An acceptable plan would include the following: ,

a. Piping System Welds Other Than in the Containment Isolation Region Ycu should provide c. cemmitment to base preservice and ,

inservice inspections on the Edition of AShE Code Section XI required by 10 CFR Part 50.55a(g).

b. High Energy Piping Systems Welds in the Containment Isolation Region Preservice and inservice inspections should be based on the auge nted IST requirements defined in SRP Section 6.6. When .

guard pipe is used in this region, you should provide sufficient access, by either inspection ports or removable guard pipe, to perform the required augmented inservice inspections.

Sincerely, ll -

n .kabda, ie Light Water Reactors R ch No. 4 Division of Project Management cc: See next page i

i I

L OCT 6 5 78 ,

Duke Power Company  ;

CCS*

William H. Grigg, Esq.

Duke Power Company P. O. Box 33189 Charlotte, North Carolina 28242 3 William L. Porter, Esq.

Duke Power Company P. O. Box 33189 Charlotte, North Carolina 28242 P

J. Michael McGarry Ill, Esq.

Debevoise & Liberman '

700 Shoreham Building (

806 15th Street, NW  !

Washington, D. C. 20006 Mr. Jesse L. Riley, President Carolina Environmental Study Group

~

854 Henley Place Charlotte, North Carolina 28208 M. Richbourg Roberson, Esq.

Staff Attorney Attorney General's Office P. O. Box 11549 Columbia, South Carolina 29211 Walton J. McLeod, Jr., Esq.

General Counsel South Carolina State Board of Health J. Marion Sims Building 2600 Bull Street Columbia, South Carolina 29201 James W. Burch, Director

• Nuclear Advisory Counsel 2600 Bull Street Columbia, South Carolina 29201 7 n ..

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