Safe and reliable reactor coolant systems
Nuclear energy is a sustainable and clean alternative to combustion of fossil fuels. Nuclear reactions in the reactor core generate tremendous amounts of heat. The coolant is not only important for electricity generation through heat transfer to a steam generator, it is also critical for safe operation. Scientists initiated the EU-funded project STYLE (Structural integrity for lifetime management – Non-RPV components) to develop models for the structural integrity analysis of RCPB components. The team worked closely with experienced operators supported by a comprehensive knowledge management database to develop realistic models of failure processes in key components. The focus was on structural integrity assessment of RCPB components under various loading conditions, including seismic activity. During the third project period, scientists developed advanced computational methods and tools to describe the complex physical mechanisms leading to ageing and failure of the reactor coolant system piping and components. Furthermore, they validated various engineering assessment methods, particularly as related to leak-before-break designs, for their applicability in large-scale demonstration mock-ups. The main focus was on evaluating weld integrity and repaired weld joints. In particular, scientists studied and simulated weld integrity of dissimilar metals, residual stresses on the weld, cracking because of stress corrosion and thermal fatigue. STYLE's end product will include best practice guidelines on the use of advanced tools and improvement and qualification of engineering assessment methods. In addition, it will include lifetime management of RCPB component integrity at European NPPs. Project partners will benchmark safety assessment methodologies on similar and dissimilar metal welds, considering both deterministic and probabilistic approaches. STYLE is developing more accurate assessment methods regarding the structural integrity of safety-critical nuclear reactor components. Project tools are expected to contribute to improved designs, enhanced cost effectiveness and greater safety of existing and future NPPs.
Keywords
Reactor, reactor coolant pressure boundary, nuclear power plant, structural integrity, engineering assessment methods
