The WRC-297 Bulletin, in Section 3.2 states "Although the shallow-shell solutions used by Steele may be valid up to a d/D ration of 0.5, the exact limit of application depends on the D/T ratio."

So, the nozzle flexibility computation in CAESAR II limits the diameter ratio to 0.5. Exceeding this generates an error message.

This has been further substantiated by the PVRC's recent work "Nozzle - Attachment Design Analysis: ASME Code and WRC Bulletins 107, 297, 368". This document lists the following limitations on WRC-297:

• Based on shallow thin Shell Theory, by Prof. Steele
• Nozzle axis is normal to the vessel.
• d/t >= 20 (However reasonable results are obtained for any d/t)
• 20 <= D/T <= 2500
• d/T >= 5
• d/D <= 0.5 (Depends on D/T ratio).
• Nozzle-Shell junction ust be a distance > 2*SQRT(DT) on the vessle and > 2*SQRT(dt) on the nozzle away from a structural discontinuity.
• Note, although the above limits are stated in the bulletin, recent work indicates that the results may be in question when the diameter ratio exceeds approximately 1/3.

So, we will be adding a new warning to CAESAR II if the d/D ratio exceeds 0.333.


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Regards,
Richard Ay (COADE, Inc.)



[This message has been edited by rich_ay (edited September 15, 2000).]