Boron-10 stimulated helium production and accelerated radiation displacements for rapid development of fusion structural materials

Abstract

Boron doping, combined with neutron capture in fission reactors, has been used to simulate the helium effect on fusion structural materials. However, inhomogeneous helium bubble formation was often observed due to boron segregation to grain boundaries. The excess radiation displacements due to 10B(n, α)7Li reaction, the high-energy lithium and helium ions, also were not accounted for, which can significantly accelerate the displacements-per-atom (dpa) accumulation alongside helium production (appm). Hereby an isotopically pure 10B doping approach is proposed to simulate the extreme environment inside fusion reactors with a high He appm-to-dpa ratio of about 10, which is about 102 × larger than in fission reactors. Computational modeling showed that ∼13% of total radiation displacement was induced by 10B(n, α)7 Li in the case of 1 000 appm 10B doped Fe samples, which becomes even greater with increasing 10B loading. Spatially homogenous radiation damage and helium generation are predicted for grain sizes less than 1 μm, even if the boron partially formed precipitates or segregates on grain boundaries. Feasibility studies with various 10B doping (and 235U-codoping) levels in research reactors showed the estimated helium generation and radiation damage would significantly mimic fusion conditions and greatly expedite fusion materials testing, from many years down to months.

Keywords

• Fusion power reactor
• Helium transmutation
• He appm-to-dpa ratio
• Boron-10 doping
• Accelerated materials testing