[en] The Small-Scale Clad Effects Study of the HSST Program was initiated to study the interaction of stainless cladding with flaws initiated in and propagating in base metal. From the designer's viewpoint stainless cladding is primarily viewed as a corrosion- and crud-prevention measure in light-water reactor vessel design, and except for its effect upon fatigue in thermal transients, its effect upon structural integrity has heretofore been largely disregarded. With the more recent focus of safety studies upon LOCA scenarios that emphasize the behavior of small flaws, it has become evident that stainless cladding may have a key role in the propagation and/or arrest of propagating flaws. A complicating factor in understanding the role of stainless cladding in this setting is its fracture toughness as a function of radiation dose and as a function of fabrication process for which meager data exist. The initial phase of this study has attempted to address this question by testing stainless-clad specimens that had been subjected to heat treatments to simulate beginning-of-life and end-of-life toughness conditions to fast-running cracks