The Network for Evaluating Structural Components (NESC) coordinated extensive materials testing and fracture analyses performed by a group of twenty European organizations. The NESC-IV project addressed the transferability of fracture toughness data from laboratory specimens to applications that assess the integrity of reactor pressure vessels subjected to upset and normal loading transients. The coordinated experimental and analytical program drew from major elements of the biaxial features testing program conducted by the Heavy Section Steel Technology Program at the Oak Ridge National Laboratory. In this context, the JRC performed impact and tensile tests in the temperature range -90 to 80ºC on type A533B ferritic steel.