Speaker
Description
The EU-DEMO fusion reactor is facing uncertainty in safety and licencing of in-vessel components that relate directly to the materials and design criteria used for assessments. These challenges come from the designed operation under unprecedented environmental conditions and reliance on the performance of complex in-vessel components over time spans of years. These critical components, including the divertor and breeding blanket, will rely on complex structures and multi-material interface that also utilise novel (in regards to nuclear environments) materials. Along with the high operational temperature and fusion spectrum irradiation effects the use of complex components provides key differences in the structural integrity and required design criteria for existing nuclear systems and the EU-DEMO reactor.
Many of the in-vessel components in DEMO have a high secondary (thermal) stress; this secondary stress can be relieved by geometrical changes that often occur in the plastic regime of materials deformation. The relaxation of stresses during plastic deformation of materials makes purely elastic analysis conservative and often makes design by analysis more challenging, potentially ruling out good designs. Most current nuclear design codes allow in-elastic analysis methodologies but have a preference to use elastic analysis with correction factors to accommodate plastic deformation, these corrections can add conservatism and inaccuracies to design. An overview of the use of in-elastic analysis methods for assessment of fusion components will be highlighted. The overview provides a representative example of a general requirement to move fusion design criteria towards alignment with modern assessment procedures that utilise in-elastic analysis as a precedence to improve design.
Overall, addressing the challenges in materials engineering and design criteria for fusion requires pragmatic adaptations and a new approach to the structural integrity case for fusion. The current pathways towards development of new DEMO specific design criteria and fusion structural integrity are reviewed.
| Eligible for student paper award? | No |
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