In view of the high demand for long and reliable operations with due considerations on economy, several innovative concepts and evolutionary features are incorporated in the current sodium-cooled fast reactor (SFR) designs. Design of SFR components adopts the philosophy of design by analysis to comply with the design codes and standards, which themselves are not sufficiently matured, that is, still evolving. Analysis through computer codes calls for several specialized and advanced concepts in the domains of structural mechanics and thermal hydraulics (refer to Chapter 9). Hence, the SFR design has to be thoroughly validated by adequate experimental programs. The computer codes employed in the design are validated normally by solving common benchmark problems and comparing the code to code results. Further, to assess their overall performance, scaled-down or full-scale experiments are conducted. Finally, the components that are designed and manufactured are subjected to various stages of qualification tests before integration with the reactor.