"Matrix Damage in Reactor Pressure Vessel Steels Under Neutron Irradiation" 

Jasmyne Emerson, MSE PhD Candidate 

Advisor: Professor Maria Okuniewski

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ABSTRACT

Reactor pressure vessels (RPVs) play a pivotal role in the safe and reliable operation of nuclear power plants. This paper investigates the complexities of matrix damage in RPV steels, focusing on the dislocation loop and void formation as they relate to neutron irradiation fluence. The study of matrix damage in RPV steels is a multifaceted task, which requires multiple techniques for characterization, such as transmission electron microscopy (TEM) and positron annihilation lifetime spectroscopy (PALS). The TEM data presented sheds light on the interplay between dislocation loop density, dislocation loop average diameter, and irradiation fluence. Transmission electron microscopy data also reveals the impact of alloying elements such as Cu, Ni, P, and Mn on the formation and growth on matrix defects. Furthermore, the influence of fluence on average positron lifetime measurements is presented, offering insights into the role of various alloying elements in shaping the formation of irradiation-induced voids. This comprehensive exploration of matrix damage aims to contribute to our understanding of how matrix damage forms under irradiation, as well as provide recommendations for future experiments to further understand matrix defects.