Helium trapping and clustering in ThO2

Atomistic simulation of helium diffusion and clustering in plutonium dioxide

“…Favourable helium incorporation in actinide vacancies has also been found in UO 2 44 and ThO 2 . 45 However, PuFPs are unstable in PuO 2 . 22 So whilst V Pu sites are the most energetically favourable for He to occupy, they may not represent the majority site available to He.…”

“…It was found that helium is most stable in V Pu sites with an incorporation energy of 0.19 eV, which is in good agreement with the 0.16 eV DFT calculated value from Neilson et al 22 Favourable helium incorporation in actinide vacancies has also been found in UO 2 44 and ThO 2 . 45 However, PuFPs are unstable in PuO 2 . 22 So whilst V Pu sites are the most energetically favourable for He to occupy, they may not represent the majority site available to He.…”

Theoretical Combined Experimental Study of Unique He Behaviors in High-Entropy Alloys

“…Structural materials used in nuclear reactors must maintain both mechanical properties (strength, ductility, and fracture toughness) and dimensional stability (against creep and void swelling). − Considering the service environment of nuclear reactors, , the insert gas helium (He) produced by ( n , α) nuclear transmutation reaction plays a negative role in the macroscopic properties of metals and alloys. , The He atom presents a strong tendency to migrate, aggregate, and form bubbles in an alloy, resulting in surface roughening, blistering, void swelling, and high-temperature intergranular embrittlement, which lead to the degradation of the materials’ mechanical strength and shorten the service time. , To ameliorate these problems, the design of structural materials with strong resistance to He damage has been proposed to be a challenging task in the advanced nuclear reactors.…”

“…9,10 The He atom presents a strong tendency to migrate, aggregate, and form bubbles in an alloy, resulting in surface roughening, blistering, void swelling, and high-temperature intergranular embrittlement, which lead to the degradation of the materials' mechanical strength and shorten the service time. 1,11 To ameliorate these problems, the design of structural materials with strong resistance to He damage has been proposed to be a challenging task in the advanced nuclear reactors.…”