ML20197J941
| ML20197J941 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/28/1986 |
| From: | George J TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Jeng D NRC |
| Shared Package | |
| ML20197J762 | List: |
| References | |
| NUDOCS 8605200214 | |
| Download: ML20197J941 (4) | |
Text
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TEXAS UTILITIES GENERATING COMPANY P. O. BOX 2300
- GLEN ROSE, TEXAS 74043 l-1 February 28, $986 Mr. David Jeng, Mail Stop 244 United States Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 I
t ATTENTION:
Mr. David Jeng
SUBJECT:
CPSES Cable Tray System Design Verification -
Recoc= ended Slenderness Ratio Dynamic System Test Configuration Gentlemen:
Please find attached for your review the recom= ended dynamic system test configuration to address the slenderness ratio limits for tension members in CPSES cable. tray supports.
The reccmmended test configuration includes two trapeze supports with very high slenderness ratios (L/R = 360) and a single longitudinal support. All three supports are representative of typical trapeze supports at CPSES. Out of straightness in excess of the maximum existing in CPSES will be provided for the transverse trapene supports. A single cable tray is located at the bottom of the trapeze supports and the cable tray is connected to the supports using clip connections representative of those installed at CPSES.
The cable fill veight for this test will be selected to maximize response by assuring that predominate system frequencies are tuned to the peak regions of the test response spectra. The cable fill weight to achieve this objective will be determined by pre-test analysis.
A single SSE level test will be performed and the system will be instrumented to verify the input, displacements in the supports, relative displace =ents between the trays and supports, and axial forces in the vertical post of the transverse supports.
This test configuration maintains the characteristics of actual cable tray systems at CPSES with long slenderness ratios. However, several significant conservatisms contained in the recommended test will provide bounding results compared to actual expected SSE response at CPSES.
These include the following:
8605200214 860514 PDR ADOCK 05000445 A
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A DIVISlo.4 0F TEXAS UTillTIES El.ECTRICC0\\tf'A 4Y
Mr. David Jeng United States Nuclear Regulatory Commission February 28, 2986 Page Two 1.
The use of a single cable tray located at the bottom of the supports provides conservative results because supports with high slenderness ratios in the plant generally have many tiers supporting cable trays at various levels. This introduces two conservatisms; a) the actual effective length factor for the test is greater than typically fcund in the plant, which reduces the compressive load required to cause buckling, and b) multiple tier; systems tend to have lower response due to coupling effects between various cable tray levels.
2.
The test configuration out-of-straightness exceeds actual plant conditions.
3.
SSE response of the test configuration is expected to produce compressive axial stresses near AISC limits while actual plant configurations generally result in ccepressive axial stresses less than ten percent of AISC limits.
4.
Actual plant supports with high slenderness ratios are generally located in the lower and middle floors of the plant while the test will be performed with enveloping spectra.
All of the above facters clearly bias the planned test to produce beunding results, which will provide conclusive evidence regarding this issue.
We trust that this plan meets all of your needi to resolve this issue.
Please contact Mr. Harvey Harrison at (817) 89/-8691 if you require any further information or have any questions regarding this matter.
Very truly yours, a
Joe B. George Vice-President JBG/jb Enclosure cc:
Mr. W. G. Council Mr. J. W. Beck Mr. T. G. Tyler Mr. J. T. Merritt Mr. R. E. Camp Mr. H.
Harrison Mr. R. D. Wheaton Mr. K. C. Warapius Mr. J. Padalino
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