NFRP 1: 2016-2017 notes that “A number of current Generation II reactors should continue operating for a few decades and Generation III should still be in operation one century from now.” This requires a systematic ageing management procedure for justifying their safe long term operation (LTO). One fundamental part in this process is to demonstrate the integrity of the nuclear power plant components. The required safety margins are determined by considering various degradation and ageing mechanisms and postulated defects. This project focuses on open technology gaps, identified in the NUGENIA road map, related to piping components, not covered by other ongoing projects. Specifically this project will focus on developing: o innovative quantitative methodologies to transfer laboratory material properties to assess the structural integrity of large piping components, o an enhanced treatment of weld residual stresses when subjected to long term operation, o advanced simulation tools based on fracture mechanics methods using physically based mechanistic models, o improved engineering methods to assess components under long term operation taking into account specific operational demands, o integrated probabilistic assessment methods to reveal uncertainties and justify safety margins. ATLAS+ will have a significant impact on the safety of operational Generation II and III nuclear power plants. The project will demonstrate and quantify inherent safety margins introduced by the conservative approaches used during design and dictated by codes and standards employed through-out the life of the plant. The outcomes from ATLAS+ will therefore support the long term operation of nuclear power plants. This will be achieved by using more advanced and realistic scientific methods to assess the integrity of piping. The project will provide evidence to support the methods by carrying out large scale tests using original piping materials.