The applications of the LBB(Leak Before Break) design concept have many advantages such as the elimination of the pipe whip restraint, elimination of the impact wall, easy inspection, easy repairment and reduction of the radioactive damage of operator, etc. To apply the LBB concept to the nuclear power plant piping system, it is necessary to measure the material properties on the pipe material. Especially, the measurements of the fracture toughness $J_IC$ and J-R curve characterizing the fracture resistance of the material are necessary.
In this study, the fracture toughness tests were conducted to investigate the effect of dynamic strain aging on the fracture toughness $J_i$ and crack propagation resistance dJ/da of SA106 Gr.C materials (base and weld materials) at several different temperatures of RT, 200℃,289℃,350℃ and different load line displacement rates of 0.4mm/min, 8.0mm/min, 840mm/min. It is found that the materials (SA106 Gr.C Steel) tested showed the DSA effect appreciably.