ML20128K149
| ML20128K149 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 06/27/1984 |
| From: | Williams N CYGNA ENERGY SERVICES |
| To: | Ballard R GIBBS & HILL, INC. (SUBS. OF DRAVO CORP.) |
| References | |
| 84042.009, NUDOCS 8507100494 | |
| Download: ML20128K149 (3) | |
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t seeom#ses 101 C.hforni. Street. Sute 1000. San Fr.ncisco. C A 94111 5894 415 3P500 June 27, 1984 84042.009 Mr. R. E. Ballard Project Manager Gibbs & Hill, Inc.
11 Penn Plaza New York, New York 10001
Subject:
Pipe Stress Review - Break Exclusion Areas Comanche Peak Steam Electric Station Independent Assessment Program - Phase 3 Texas Utilities Generating Company Job No. 84042
Reference:
1.
Mr. R.E. Ballard (G&H) letter to Mr. J.B. George (TUGCO),
GTN-69098, June 11, 1984; Texas Utilities Generating Company, Comanche Peak Steam Electric Station Followup information from G&H, Ref. Cygna Communications Report of 5/24/84.
2.
Communications report between H. Mentel (G&H), N. Williams (Cygna) and L. Weingart (Cygna), June 20, 1984 Dear Mr. Ballard Cygna has received and reviewed Gibbs & Hill's response concerning welded attachment stresses in break exclusion zones (Reference 1). As noted in the response, only the membrane portion of the local stress was included in the G&H re-evaluation of those attachments located in break exclusion zones.
It is Cygna's position that local bending stresses should be included as well. The basis for this position is as follows:
The Class 2 criteria in MEB 3-1 permit break exclusion zones if the primary (equation 9) and secondary (equation
- 10) pipe st-esses meet certain limits. The fact that HEB 3-1 does in6end the primary, secondary and fatigue effects to be considered is evident by reviewing the Class 1 criteria. For Class 1, HE8 3-1 limits the equation 10 (primary plus secondary) pipe stress to 2.4 S and the g
fatigue usage factor to 0.1.
Stresses above these limits require break postulation. The intent of MEB 3-1 is, therefore, to limit the potential for crack formation (i.e., limit fatigue). To determine fatigue stresses, one 7l) must consider the total stress at a point, not just the primary effects. This is apparent from the Class 1 break shh45 1
P 4
a)
.... -.. -. -. n
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SitVKES Mr. R. E. Ballard June 27, 1984 Page 2 criteria. Finally, MEB 3-1 has effectively stated that secondary / fatigue effects should be considered for Class 2 by including equation 10, which limits both secondary and fatigue stresses for Class 2.
Therefore, when welded attachments are present, the total stress (local membrane plus bending) should be considered in order to meet the intent of HEB 3-1.
We would like to discuss this interpretation with you as soon as possible.
Please call when you have completed your review.
Very truly yours, N. H. Willlams Project Manager cc Mrs. J. Ellis (CASE)
Mr. S. Treby (NRC)
D.TERoo J. Fn,R, D.Woere f.c r -d Ms. S. Burwell (NRC) A J
Mr. D. Wade (TUGCO)
Mr. G. Grace (TUGC0/BASCO)
Mr. D. Pigott (Orrick, Herrington & Sutcliffe)
Mr. H. Mentel (Gibbs & Hill)