Irradiation Embrittlement on a Core Shroud from Decommissioned BWR

Sammanfattning: Irradiation embrittlement is a problematic issue for internal structures, such as acore shroud, in a light water reactor. It is characterized by decreased ductility andtoughness, and increased yield strength and hardening due to increased dislocations.Before this thesis a core shroud from a BWR was cut into pieces based on the estimatedneutron damage on the welds. Two of the pieces cut out was used in this thesis, A2( 0.5dpa) and C2(<0.1 dpa). In this thesis Vickers hardness tests and uniaxial tensile testswere used to give an estimation of the embrittlement of the welds. An estimation ofyield strength of A2 was also calculated based on the resulting hardness. The Vickerstests showed noticeable hardening in the weld, both at 0.1 dpa and 0.5 dpa. The ATTalso showed an increase in yield strength in C2. The calculated yield strength alsoshowed an increase. In conclusion, the core shroud has a decreased toughness, henceincreased risk of unexpected brittle fracture.