ML20140B799

Safety Evaluation Supporting Subcompartment Pressure Analysis & Proposed Valve Room Design,Per Low Stress Superpipe Requirements of Branch Technical Position Meb 3-1 Re Protection Against Main Steam or Feedwater Line Breaks

ML20140B799
Person / Time
Site:	South Texas
Issue date:	06/06/1977
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20140B735	List: ML20140B760 ML20140B799 ST-HL-AE-1582, Clarifies 851024 Response to NRC Request for Study of Jet Impingement Effects in Break Exclusion Area of Main Steam & Feedwater Piping.Encl NRC & Safety Evaluation Cited to Support Claim That Study Lacks Justification
References
ST-HL-AE-1582, NUDOCS 8601270134
Download: ML20140B799 (2)

Text

. . . b;

,., . r

(. . ,

• ATTACHMENT .'

ST HL AE. I St A PAGE a OF3 SAFETY EVALUATION OF THE DYNMilt EFFECTS OF p0STULATED PIPE

FAILURES OUTSIDE CONTAINMENT - SOUTH TEXAS PROJECT UNITS 1 AND 2 l

I' In response to our concern of routing the steam lines near safety systems." -

6 the applicant submitted the report " Dynamic Effects of Postulated Pipe S Failures Outside Containment - South Texas Project Units 1 and 2" for our

• review. \. '

[

I  !

Our review covered the protective features provided for individual systems .

and a review of preliminary piping layout drawings. The applicant's original 9, design of the main steam and feedwater piping systens proposed a break

?.

exclusion area for the piping in the main steam and feedwater valve rooms.

. kp This was based on meeting the low stress. "superpipe" requirements of e, Branch Technical position MEB 3-1. However, the report showed that I.,

all four auxiliary feedwater pumps for the South Texas Project will be located V.]. ..

below these valve ronms. For safety, in addition to the low stress piping, pr.

we . required the applicant to design the valve rooms to withstand the environ- '

i '

.[

h, mental effects of a main steam or feedwater line break equivalent to the pb flow area of a single ended pipe rupture.

, ry r.;

As a result, the applicant proposed to redesign his main steam and feedwater ,

valve rooms with a vent area capable of venting the release of larger than ,

one equivalent single ended pipe break and provided a subcompartment pressure .;

4. ,

ana. lysis to show that the rooms would withstand the environmental effects of

,, ,.. N. :

a break in this area.

, e601270134 e50150 - I;

.. PDR ADOCK 05000498 '

.. A PDR

)

f 6.

W $ l

. .. . . , , ... . ... l

- . ,u,.

g .,

. gr ., , '

.- '. .: - t ATTACHMENT i. ..

• . 2  ; ST HL AE.15?L -

PAGE 30F 3 l.

I We have reviewed the results of the applicant's subcompartment pressure analysis and have also performed our own independent analysis of their if:-

new valve room design and find that the proposed design is now in I ace:rdance with our Branch Technical Position APCSB 3-1 and therefore acceptable. t

-+

. g h

1

. S..

s. l n

p.

l e..

M 6

-'e-

. .: r2 v.

L*1 P

V (tQ s

g

, .. . s* - ,

.: f 5

. r

.s . . .

1 *