ML20215B409

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Rev 0 to Clarification of Impell Cth Design Verifications Criteria/Methods for Resolution of Cygna Audit Concerns, Effects of Thermal Loading on Cable Tray Sys
ML20215B409
Person / Time
Site: Comanche Peak  Luminant icon.png
Issue date: 05/15/1987
From: Ashley G
ABB IMPELL CORP. (FORMERLY IMPELL CORP.)
To:
Shared Package
ML20215B058 List:
References
IM-P-006, IM-P-006-R00, IM-P-6, IM-P-6-R, NUDOCS 8706170317
Download: ML20215B409 (6)
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CLARIFICATION OF IMPELL CTH DESIGN VERIFICATION CRITERIA / METHODS FOR RESOLUTION OF CYGNA AUDIT CONCERNS i Effects of Thermal Loading on Cab 1'e Tray Systems i

Prepared for:

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Texas Utilities Electric Company Prepared by:

Impell Corporation i l

0210-040/041 IM-P-006 Revision 0 Prepared by: cr. fy/./Og J,,,,g r//g/g 7 t

Approved by: ((M 5-/r-g7 C/

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CONCERN: CYGNA has~ requested clarification on the Impe11 position regarding the consideration of thermal loads on CPSES cable' tray systems.

DISCUSSION: Impell Calculation M-27 Rev. 2 [1] documents that the provisions of the CPSES FSAR allowing the exclusion of

-thermal loading from design verification have been 1 satisfied. The cable tray and support assemblies are '

ductile snd the thermal displacements are secondary in-nature and shown.to be self limited to values which preclude structural-failure.

Impe11 Calculation M-27 specifically addresses the deformational capacity.of the steel-to-concrete anchorages. '" Worst case" thermal . displacements are estimated for both normal operating and accident conditions. These displacements were calculated based on a maximum (40'-0") ~section of longitudinally ~ unrestrained cable tray. System slack is' evaluated based'on hole oversize determined from sampling [2]. Normal operating-and accident thermal displacements which may occur during the duration of a seismic event were shown.to be self limited to values which would.not overcome the system slack.

Also evaluated were the maximum thermal displacements- -

which may occur. at any time during the accident (i.e.,-

the heat-up time was not' restricted to the duration of an ,

assumed initiating seismic event). This condition-represents the largest thermal growth which could occur for the cable tray.

A support and base angle configuration, as'shown in Figure 1, was selected to represent " critical" tension and shear conditions for a critical anchor bolt. The calculation details the assumptions made to determine this configuration. _ The equilibrium tension and shear bolt deformation required to accomodate the calculated thermal tray displacement was determined. To truly represent " worst case" conditions, none of:the available slack was assumed to be mobilized. Figure 2 illustrates the tensile equilibrium point for a .1" Hilti~ Figure 3 shows a similar curve for a 1" Richmond. -Shear equilibrium values were considerably less significant for

, both bolts. The significant displacement capacity remaining for both bolt types indicates that ,

substantially higher thermal displacements than the

" worst case" calculated could be accomodated by the anchorages.

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A further study was done for a longitudinal support intended to represent a critical case .for bolt shear-alone, This condition would occur for a clamp bolted directly to a concrete floor or wall. These support types are relatively rare at CPSES and even more uncommon in the reactor building. Both Hilti and Richmond anchorages were shown to be able to accomodate the calculated " worst case" thermal displacements. For this case it was assumed that the available slack would be mobilized by slippage due to the relatively high axial '

forces generated in the tray.

CONCLUSION: The calculation concluded.that, for all components of the cable tray and support system the thermal loads were secondary and self-limiting in nature and the materials sufficiently ductile so that failure could not occur.

REFERENCES:

[1] Impell Calculation M-27 Rev. 2 " Thermal _ Load Evaluation"

[2] " Statistical Analyses of Bolt Hole / Edge Distances in CTH i Supports" Ebasco Study Volume I, Book 22.

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