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Alloy Design For A Fusion Power Plant

Alloy Design For A Fusion Power Plant. Richard Kemp. Objective. Design a material, with the right properties, that is stable under irradiation One of the biggest problems in commercial fusion power research. Fusion Power. Combination of light nuclei into heavier nuclei

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Alloy Design For A Fusion Power Plant

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  1. Alloy Design For A Fusion Power Plant Richard Kemp

  2. Objective • Design a material, with the right properties, that is stable under irradiation • One of the biggest problems in commercial fusion power research

  3. Fusion Power • Combination of light nuclei into heavier nuclei • Same process as occurs in the sun • Produces heat • Releases neutrons

  4. Surface Damage

  5. First Wall Material Design Problems • Activation • Swelling • Irradiation Hardening • Irradiation Creep

  6. Activation • Material becomes radioactive waste • Need low activation alloying elements

  7. Radiation Damage • Cascade formation of vacancies and interstitials • Often measured in dpa • Formation of defect structures • Preferential diffusion

  8. Radiation Damage - Cascades

  9. Radiation Damage

  10. Swelling • Transmutation helium produced in material • Bubbles form and grow • Macroscopic shape changes are undesirable

  11. Swelling

  12. Irradiation Hardening • Microstructural changes • Vacancy loops • Radiation induced precipitation • Helium bubbles • Shift in DBTT

  13. Irradiation Creep • Increased diffusion within material • Related to dose rate rather than temperature • Can lead to premature failure of material

  14. Solutions • Reduced activation steels • Low swelling steels • Careful study of changes of properties under irradiation

  15. Approaches • Numerical modelling • CULRAM and EASY software • Neural network modelling

  16. Numerical Modelling • Useful for solving systems of differential equations • Rate Theory approach Rate of change = diffusion + sources - sinks

  17. Neural Network Modelling • Used for fitting curves to points • Mechanical properties as a function of composition and heat treatment • Need a good data set! • RAFM database • Physically sensible inputs

  18. Neural Network Modelling • Irradiation hardening in F82H • Inputs: estimated increase in dislocation density and bubble size • Output: Increase in yield strength

  19. Neural Network Modelling

  20. Ongoing work • Modelling and optimisation of properties of low activation steels • Greater understanding of swelling processes and how to minimise this

  21. Acknowledgments • Harry Bhadeshia • Geoff Cottrell • Culham Labs

  22. Any questions?

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