ML20137X394
| ML20137X394 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 10/01/1985 |
| From: | Hou S NRC |
| To: | Fox J AMERICAN NUCLEAR SOCIETY, GENERAL ELECTRIC CO. |
| Shared Package | |
| ML20137X398 | List: |
| References | |
| TAC-57279, NUDOCS 8603060213 | |
| Download: ML20137X394 (2) | |
Text
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NUCLEAR REGULATORY COMMisslON y
3 ky WA!HlWGTON, D. C. 20!.55 e
ET 11985 Mr. Jack N. Fox, Chairman of ANS-58.2 Working Group i
General Electric Company Nuclear Systems Technology Operation 310 DeGuigne Drive, M/C S-65 Sunnyvale, CA 94086
SUBJECT:
COMMENTS ON DRAFT REVISION 2 0F ANS-58.2
Dear Mr. Fox:
A draft justification for revising the cumulative usage factor from 0.1 to 0.4 in selecting postulated pipe break locations is enclosed for working group consideration.
My comments on the draft consist of the the following: (1)Thesingle pressure test of guard pipe assemblies as currently stated in Section 4.(111) appears reasonab.c.
(2) The postulation of through-wall cracks as stated in page 4-3 is confusing.
Revise to confonn with MEB 3-1, i
Sec. B.2.c and 8.3.c. or let's have more discussion.
I assume that pu will incorporate consnents from Keith Wichman on leak-before-break as he suggested in last meeting.
Besides, may I consnent on jet impingment section after having Dan Peck's simplified model di.scussed in next meeting.
The model appears somewhat different from what we concluded last time.
Sin rel y, Shou N. Hou
Enclosure:
As stated i
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ATTACHMENT
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_PAGE JL OF 7 usage factor: MISC 7 y
Draft 1 - 9/29/85 JUSTIFICATION FOR REVISING THE CUMULATIVE USAGE FACTOR IN SELECTING POSTULATED RUPTURE LOCATIONS In both ANS-58.2-1980 and Section 3.6.2 of the NRC Standard Review Plan (NUREG-0800), pipe break locaticns in Class 1 piping are postulated based on a criterion where either the cumulative usage factor (CUF) exceeding 0.1 (a factor of 10 to Code allowable) or the stress intensity range exceeding 2.45m (80% of Code allowable). The larger margin adopted on CUF is-due to uncertainty of vibratory loads which may not be adequately accounted for in the design.
With the implementation of ANSI /ASME Standard OM 3, " Requirements for Preoperational and Initial Startup Vibration Testing of Nuclear Power Plant Piping Systems," we believe that uncertainty in vibratory loads will be f
'significantly reduced. Although we are unable to quantify exactly the amount of reduction of such uncertainty, we believe an additional factor of 2 to 80% Code allowable is adequate to account for the uncertainty. This leads to a suggestion that a pipe break postulation criterion based on CUF exceeding 0.4 be used instead of using the factor of 0.1.
Investigation by NRC consultant, Mr. E. C. Rodabaugh, confirms that a compatible relationship exists between the 80% reduced allowable stress and the 0.4 usage factor (See attachment).
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