ML20031G428
| ML20031G428 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 10/19/1981 |
| From: | Trickovic R BECHTEL GROUP, INC. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19260J188 | List: |
| References | |
| VB-81-0563, VB-81-563, NUDOCS 8110220417 | |
| Download: ML20031G428 (4) | |
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- gPNIl4q, Bechtel Power Corporation (J
(4' Engineers-Constructors 4 0013 S jgBlP 'k.
15740 Shady Grove Road cu.$
Gaithersburg, Maryland 20877 ppp 301 - 258-3000 October 19, 1981
\\'VI United States Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Licensing Washington, D. C.
20555 Attention:
Mr. Harold R. Denton, Director
Dear Mr. Denton:
Nuclear QA Is Applicable Middle South Energy, Inc.
Grand Culf Nuclear Station Bechtel Job No. 9645 File: 0262/L-350.0/L-334.0 NRC Request for Information Cable Tray Tests Docket No.'s 50-416, 50-417 Units 1 & 2 VB-81/0563 Per NRC request at the October 5,1981 meeting between the NRC, MP&L and Bechtel, attached are responses to informal questions on cable tray tests.
This information is confidential and proprietary to Bechtel Power Corporation and, therefore, is being submitted to you directly by Bechtel Power Corporation as an agent for Mississippi Power and Light Company (MP&L).
Under terms of our affidavit and cover letter, D. E. Huffman, Bechtel Power Corporation, to Edward C. Shomaker, NRC, dated June 6,1980, the attached information is of the type described in the affidavit and cover letter and should be treated as confidential and proprietary for the same reasons as the prior submitted information.
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Very truly yours,
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'Attehment to be Withheld R. S. Trickovic Ib From Public Disclosure Project Engineer 6
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Bechtel Power Corporation United States Nuclear Regulatory Commission October 19, 1981 Bechtel Job No. 9645 VB-81/0563 ALW:nll
Enclosures:
Responses to Informal Questions on Cable Tray Tests Summary Calculation C-H164.0 Summary Calculation C-H162.0 Summary Calculation C-H161.0 Summary Calculation C-H162.0 Summary Calculation C-H163.0 Bechtel Design Guide C2.7 Grand Gulf Design Criteria - Section 13 cc:
J. P. McGaughy, Jr., w/o C. K. McCoy, w/o L. F. Dale, 2w/o T. E. Reaves, w/o Dr. D. C. Gibbs, w/o L. Ruhland, w/o J. N. Ward, w/o A. Zaccaria, w/o D. M. Doyle, w/o C. D. Wood, w/o J. D. Heaton, w/o D. E. Stewart, w/o R. J. Casamento, w/o M. D. Archdeacon, w/o J. D. Richardson, w/o 4
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! to VB-81/0563 Page 1 of 2 RESPONSE TO INFORMAL QUESTIONS ON CABLE TRAY TESTS Bechtel's Electrical Raceway Test Program was partially funded by MPSL. The Grand Gulf Project had significant input as to materials, support types, connections, etc. to be tested. This assured that the program, which sought to understand the dynamic characteristics and behavior of Raceway / Support Systems, was representative of realistic power plant installations.
Its purpose, however, was not to qualify particular support configurations by testing but rather to develop a methodology for mathematical modeling, analysis and design of raceway supports. The results of the testing ultimately took the form of Bechtel's standard design Guide C2.7 which is referenced by and forms the major substance of the Grand Gulf Design Criteria.
A wide range of variables was studied, and a great number of full scale tests, some two thousand in all, were performed.
Supports ranged from very flexible, unbraced configurations to extremely rigid (i.e., trays bolted directly to the test stand). Coherence of observed results validates the extension of the program's findings to support configurations other than those specifically tested.
Damping values as high as 20 percent of critical damping were conservatively recommended in C2.7.
Grand Gulf began using higher damping values at an early phase of the testing, before 20 percent had been validated, and che.c to go no higher than 15 percent damping.
The dominant mechanism of damping was found to be energy dissipation through cable movement. This results in lower damping for smaller percentages of cable fill. The bounding stress case, however, has been shown to be fully loaded trays f or which the higher damping is more than offset by the effects of greater mass. On Grand Gulf, all supports are designed assuming 100 percent full raceways.
A further source of conservatism in Grand Gulf's raceway support designs is the fact that our standard support types are generally designed using envelope response spectra which represent a worst case for all seismic Category I structures.
Supports installed in any but the critical enveloping building locations are thereby automatically validated for 'g' levels higher than they will experience.
Based upon the Raceway Test Program and the additional project unique conservatisms applied to design as noted above, the adequacy of Grand Gulf raceway supports has been established.
to VB-81/0563 Page 2 of 2 The following calculation summaries are provided to illustrate typical standard supports used on the project.
Included are sketches of the supports, mathematical models ured for computer analysis when appropriate, and a summary of final member atress checks.
Support Type Calc Reference 69 & 69A C-H164.0 45 & 45A C-H162.0 1&2 C-H161.0 5
C-H162.0 203 C-H163.0 i
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