The lecture on nuclear materials and reactor materials is continued, linking the material properties we learned by watching the Finnish hydraulic press with the defects created by radiation damage. Key measures of reactor material health are discussed, from ductility, to ductile to brittle transition temperature (DBTT), to radiation-accelerated corrosion via radiolysis and elemental segregation are shown. Prof. Short introduces a technically riskier part of his research, aimed at directly measuring the stored energy of radiation defects as a better quantifier of material damage.