Abstract
Containment vessel is an important structure to prevent a significant and sudden radioactive release under the severe accidents. In case of the severe accidents, the pressure generated in the containment vessel is supposed to exceed the maximum design pressure. The required function of the containment vessel as radiological confinement should be enhanced, as far as reasonably achievable. To clarify the progress of events under the severe accidents and design the severe accident countermeasure equipment, it is necessary to evaluate the pressure toughness of containment vessel boundary adequately. The containment vessel of fast reactor is composed of the various structures, and the one of the most thin boundary structure is bellows structure to absorb the thermal expansion of the coolant piping penetrating the containment vessel. In addition, the cover gas bellows of the intermediate heat exchanger has important role when the progress of the events under the severe accidents is considered. Therefore, in order to develop the evaluation method of the pressure toughness under the severe accidents, the burst pressure tests of the bellows structure subjected to internal pressure was performed.
