ML20209J270
| ML20209J270 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 01/22/1987 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | Degrassi G BROOKHAVEN NATIONAL LABORATORY |
| References | |
| VPNPD-87-32, NUDOCS 8702060265 | |
| Download: ML20209J270 (2) | |
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Wisconsin Electnc eomcouw 231 W. MICHIGAN,P.O BOX 2046, MILWAUKEE.Wl53201 (414)277-2345 VPNPD-87-32 January 22, 1987 y R SS
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'Mr. Giuliano DeGrassi Department of Nuclear Energy
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y BROOKHAVEN NATIONAL LABORATORY Building 129, 60 Cornell Street Upton, New York 11973
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Dear-Mr,
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MAINSTEAM OUTSIDE CONTAINMENT ENERGY ABSORBER APPLICATION
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This letter is to confirm responses to your questions regarding the modelling of piping in the relief valve manifold area for the subject system.
Question:
Why are the hangers at nodes 35 and 390 excluded from the weight analysis?
Response
There are three rigid hangers on each of the 30" relief valve manifold lines.
Starting from the main steam line, the distance between the first two hangers on each manifold is 30", and the distance between the second and third hangers is 56".
The hanger in ques-tinn is t-h e mi ridi a one nn each manifold.
Due to its proximit M o the other two hangers, the middle hanger has little of(ect on the overall system gravity response.
If included in the model, nonconservative (lower) force calc'ulations would result at the loca-tions of the other tw'o3 hangers.
Under the weight loading, the pipe has an uplift of.001" at the middle hanger, and thus any minute gap at this hanger will negate its restraining function.
The middle hanger, however, is included for other load cases for conservative hanger loads.
Question:
Why are the 6"-EB-1 lines at the end of the relief valve manifolds not included in the model?
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Mr. Giuliano DeGrassi 3
January 22, 1987 Page 2
Response
In the original analysis of the system done,for IE Bulletin 79-14, the 6" line was decoupled from the system based on the small moment-of-inertia and mass ratios relative to the 30" diameter manifold line.
This decision is justifiable based on the following:
1)
The mass of the 6" line is appr6ximately 13% of the mass of the relief valve manifold line, and including it in the model would lower the fre-quency of the system by approximately 7%.
How-ever, the system frequency would remain in the rigid range since the. manifold line is so rigid and located so closely to the system anchor.
Therefore, any change in response would be insignificant.
2)
Based on a simple cantilever model, the 6" line has a fundamental frequency of 15 Hz.
When coupled with the manifold line, it would have a fundamental frequency of 10 Hz.
From the input response spectra, both the 10 Hz and 15 Hz fre-quencies are within the rigid range region with only a.35g response for DBE.
At this loading level the DBE stress at the connection would be limited to a maximum of 8 ksi.
We trust that our responses provide sufficient justification as to the validity of the modelling decisions utilized by Bechtel.
We are additionally transmitting a copy of the ME101 analysis of the system weight and thermal expansion load cases after correct-ing the dimensional error between nodes 245 and 250, in accor-dance with our commitment in our letter to you dated January 8, 1987.
As expected, the correction had little impact on the responses, confirming that the seismic load case need not be reanalyzed.
If you have any questions or need further information to complete your analysis, please contact me.
Very truly, ours, b.
fibu ih C. W Fay:
Vice President Nuclear Power Enclosure Copy to Mr. George Lear, Project Director (w/o/e)
PWR Project Directorate 1