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INKA is a test facility designed by Framatome and built in the technical center in Karlstein. The original objective for establishing this test rig was the investigation of the performance of the passive safety systems developed in a new Framatome Boiling Water Reactor (BWR) design – KERENA. INKA was constructed in the scale of 1:1 in heights while the total volume of the containment was replicated in 1:24. Since the geometries of particular safety systems are faithfully reflected, their actual performance in the original plant can be investigated at the full scale. Due to the unquestionable interest of the nuclear community in the inherent safety, not only new BWR and PWR designs are equipped with the passive systems, but also particular passive solutions are considered to be applied into the already existing Light Water Reactors (LWR). In this context and due to the fact that both, single component tests and integral tests can be conducted at INKA, the facility can be employed for a demonstration/qualification of a large range of passive safety systems foreseen for quite different types of LWRs. Hence, the goal of the EASY project was the experimental confirmation of the passive systems performance and the analysis of their interactions between each other in the integral tests. Besides, the overarching target of all tests performed at INKA is provision of data for codes validation. This paper presents major outcomes and conclusions drawn on the basis of EASY project results.

Under cyclic loading in combination with high local stress levels a change in stiffness of connection points, e.g. spot welds, self-piercing rivets or flow drill screws can be observed. This paper introduces a numerical approach for the simulation of stiffness changes in vehicle structures under multiaxial cyclic loading as a result of the stiffness degradation of individual spot welds. The basic approach is based on a conventional damage accumulation combined with a power law representing the change in the spot weld’s stiffness. Instead of an accumulated damage value D a residual stiffness is set as failure criterion. Extensions to the approach are presented for its application to multiaxial loading with variable amplitudes. A conventional multiaxial fatigue test of a complete vehicle, focusing on its rear end including global stiffness and local strain measurements at the beginning, median and at the end of the test are presented and compared to the simulated results. This computation approach allows a more reliable fatigue assessment in comparison to a fatigue analysis which does not consider stiffness changes. The damage propagation after the crack initiation at an individual spot weld is represented more accurately as subsequent changes in the load paths are considered.