Research by an international consortium could lead to extensions in the operational lifespan of nuclear power plants around the world.

The INCEFA-SCALE programme aims to reduce uncertainties about how critical components will perform when subjected to the harsh conditions inside operational reactors. 

Greater certainty about component performance will avoid unnecessary closures of power plants when they are still economically viable and safe to operate.

Although components and materials are extensively tested in laboratories, there are sometimes gaps in understanding the correlation between these tests and actual performance. This means that fatigue assessment parameters must be set more conservatively than necessary.

The research will fill in those gaps by means of extensive data mining in international fatigue databases and detailed examination of test specimens to improve mechanistic understanding. This will include data made available through international fatigue database agreements.

Testing will be focused on particular aspects of component scale cyclic loading, such as:

• Notched specimens (complex loads);
• Membrane tests (biaxiality);
• Thermo-mechanical tests (thermal cycles and thermal gradients);
• Complex waveform tests (realistic plant transients).

INCEFA-SCALE is led by Jacobs and the consortium comprises Teknologian  Tutkimuskeskus Vtt OY, Paul Scherrer Institut, UJV Rez a.s., Institut de radioprotection et de surete nucleaire, Kauno Technologijos Universitetas, Centro de Investigaciones Energéticas, Medioambientales Y Tecnológicas, Centro De Investigaciones Energéticas, Medioambientales Y Tecnológicas, Universidad De Cantabria, Korea Atomic Energy Research Institute, University of Manchester, Commissariat à l’Énergie Atomique et aux Énergies Alternatives, Joint Research Centre-European Commission, Framatome, Électricité de France, Inesco Ingenieros, and Rolls-Royce Submarines Ltd.

Jacobs, the global technology-forward solutions company and operator of the UK’s largest independent nuclear laboratory complex in Birchwood Park, Warrington, will contribute to multiaxial, thermo-mechanical and complex waveform testing to give a greater insight into the stresses and strains placed on components. These will complement component scale tests being carried out in the USA by the Electric Power Research Institute, which is collaborating with INCEFA-SCALE.

The European Union, which is providing most of the funding for the five-year, $8.1 million INCEFA-SCALE program, estimates the contract value to Jacobs as $1.2 million. It is a continuation of the previous INCEFA-PLUS program, where Jacobs has been leading a 16-member European consortium since 2013. There will be a seamless continuation in the emphasis on data quality and consistency pioneered for INCEFA-PLUS.

INCEFA-PLUS was divided in two main parts. The first focused on the characterization of a limited selection of typical austenitic stainless steel alloys employed in NPPs, testing for the effects of mean stress/strain, hold time periods and material surface finish on fatigue endurance. The second part involved detailed statsistical analysis of experimental results, leading to the underpinning of current US, French and UK fatigue assessment procedures, developed to remove unnecessary conservatisms in current USNRC Environmental Assisted Fatigue guidance.

“This is the first time the European Union has sanctioned a follow-on project whilst the predecessor project is still live, which testifies to the success of the consortium and the relevance of the study topic to nuclear plant safety and lifetime assessments,” said Jacobs Critical Mission Solutions International Senior Vice President Clive White. “By successfully leading this research, Jacobs has demonstrated its capability to knit together an international consortium and to bring together the very best, complementary capabilities.”