An Experimental Rig and Investigation of Steam Generator Tube Loading During Main Steam Line Break

Abstract

Steam generator tubes in the U-bend region vibrate due to secondary side cross-flow, resulting in fretting wear that reduces the margin of safety against failure. In the event of a main steam- line-break, a rapid blow-down of pressurised water produces a high-velocity steam-water flow across the tubes, which induces potentially catastrophic transient loading that is difficult to predict. Tubes in CANDU steam generators that cannot withstand the transient loading could leak irradiated primary side fluid into the secondary side, which passes outside of the containment. The objective of this experimental study is to develop a better understanding of the transient loading.