[en] Thermal-shock experiments with steel cylinders have been conducted at ORNL to investigate the behavior of long axial inner-surface flaws during loading conditions similar to those imposed by a PWR LOCA. The scope of the three most recent experiments was dictated by results of the PWR-LOCA fracture-mechanics analysis and included: initiation and arrest of shallow and deep flaws, a series of initiation-arrest events with deep penetration of the wall, long crack jumps, arrest in a rising K₁ field, and warm prestressing. For the purpose of designing the experiments and evaluating their results, the static initiation and arrest toughness curves were determined for the test cylinders, and this was done using compact specimens. The experiments demonstrated WPS and arrest in a rising K₁ field and indicated that LEFM is valid for thermal-shock loading