Extension to Transferability of Small-Specimen Data to Large-Scale Component Fracture Assessment (TRANSFER-EXT)

The integrity of piping components of a nuclear reactor is vital to ensure the supply of coolant to the core at all times during the plant lifetime. One of the inputs to demonstrating integrity is a fracture mechanics assessment to demonstrate defect tolerance. Within the existing TRANSFER project, simplified defect assessments have been performed to estimate the loads for ductile crack initiation for both straight pipes and elbows of various pipe diameters and with various sizes of defect. The estimates have been found to be close to or conservatively predict experimentally measured loads to crack initiation, when using modern stress intensity factor and limit load solutions with the Failure Assessment Diagram (FAD) approach of the defect assessment procedure R6. Within the extension to TRANSFER, it is planned to extend this validation of practical defect assessment methods on real large-scale piping components to address the effects of constraint on the ductile tearing which occurs after crack initiation. The extension will also maximise the impact of the overall TRANSFER project through presentations at the 23rd conference on Structural Mechanics in Reactor Technology (SMiRT) to be held in Manchester in August 2015.

It is planned to incorporate the validation data from the TRANSFER project in the "Validation and Worked Examples" chapter of R6, the UK nuclear industry standard for defect assessments which is also used in India, so giving confidence in the use of this methodology for complex geometries and loadings. It is planned that the extended validation for ductile tearing and constraint effects that will be produced during the extension to TRANSFER will also be included in R6, enabling advantage to be taken of the additional load carrying capacity beyond ductile initiation.

The fracture consortium will continue to encourage engagement with various academics working in the field (including material scientists, engineers, corrosion scientists etc), and facilitate: (a) the sharing of results, capability and future research plans; (b) the development of new collaborations and resource/facility sharing; and (c) the transfer of joining technologies from other fields into nuclear.

Within the extension to TRANSFER, it is planned to maximise the impact of the overall project through presentations at the 23rd conference on Structural Mechanics in Reactor Technology (SMiRT) to be held in Manchester in August 2015.