Transferability of small-specimen data to large-scale component fracture assessment

The integrity of the piping components of a nuclear reactor is vital to ensure the supply of coolant to the core at all times during the plant life span. One of the inputs to demonstrating integrity is a fracture mechanics assessment to demonstrate defect tolerance. Within the UK, the R6 procedure is the nuclear industry standard for demonstrating such defect tolerance. R6 contains a hierarchy of assessment approaches. A difficulty in ensuring structural integrity using the higher level methods is the demonstration of transferability of fracture parameters determined from specimens to the application at component level. A large number of tests have been performed on reactor grade piping components of the Indian Pressurized Heavy Water Reactor (PHWR) to improve understanding of transferability. The tests consist of straight pipes and elbows, with a variety of cracks and loadings. This project will assess these tests using a range of defect assessment approaches to demonstrate transferability for practical piping components.

Beneficiaries: Worldwide there is year-on-year increase in consumption of energy, whilst at the same time there is increasing pressure to reduce carbon emissions. Current and advanced designs of nuclear fission plant will play a role in meeting these demands and the outcomes of this project are aimed at creating an approach to ensuring that piping components in such plant can operate safely and for extended periods of time. We have been actively involved in informing decision makers and regulators at the highest level in Government and industry, and assisting in the vital task of rebuilding public confidence in nuclear power. We also have strong track records for promoting the impact and benefits of our work to the non-academic community. This is evidenced by our number of strategic industrial partners, which include Rolls-Royce and EDF-Energy. The proposed research is also embedded in strategic work to ensure safe operation of the current and future fleet of civil and defence nuclear reactors systems. The benefits derived from this project are to be fed directly to these companies and their defect tolerance assessment approach. Our outcomes will also be widely disseminated through the Technical Advisory Group for Structural Integrity (TAGSI) and BSI where the applicants have made extensive contributions.

Links created with NDA and NNL through the existing EPSRC Nuclear Fission programme enable us to extend our framework to materials research, as the piping tests involve materials relevant to next generation plant. Within Europe non-academic beneficiaries include AREVA (France and Germany), EDF and CEA through EURATOM research programmes such as INGENIA, PERFORM60 and STYLE. In the broader context of the rest of the world we envisage opportunities to inform and network companies we already work with and include in Japan; Hitachi Group and Toshiba; in USA, Westinghouse, EPRI and NRC together with several major engineering consultancies including EMC2, and Dominion Engineering.

Benefits: Specific impacts are expected to be achieved quickly through inclusion of the outcomes of the research in revisions to the nuclear industry defect assessment procedure R6. A significant impact will also be the creation of trained and skilled researchers who will have an understanding of the nuclear industrial community.

Engagement: Our previous experience with users and beneficiaries has demonstrated that there are several effective routes for engagement and these will constitute the main basis for our communication and engagement plans. The plans (given in detail in the Impact Plan) will be managed by a group, chaired by the project PI, Prof Bob Ainsworth. The plans include routes for direct commercial exploitation, through to networking workshops that we will conduct throughout the research project.