Advanced Estimation on Fluidelastic Instability of U-Bend Tube Bundle of Steam Generator. 2nd Report. Fluidelastic Vibration by HFCF-123 Fluid Two-Phase Flow.

Abstract

A partial but full-size mock-up test of practical steam-generator U-bend tubes in nuclear power plants has been carried out, where the test model has been set in a HFCF-123 fluid two-phase flow loop. U-bend tubes are supported with so-called "Anti-vibration Bars (AVB) ", which have two types of AVBs in Japan, 7-span type and 5-span one. Both types of AVBs have been examined and it is found that tubes with AVB supports shows no large amplitude vibration up to 150% flow rate to the practical condition. Basic data for the fluidelastic instability are obtained when some tubes have been set to be flexible at some contact points with AVBs.