TEM study of beryllium pebbles after neutron irradiation up to 3000appm helium production

TEM study of impurity segregations in beryllium pebbles

“…This result was also confirmed by TEM investigations of irradiated beryllium powder [6]. However, the pebbles in some areas were observed to have a nano-grain structure.…”

“…The details of this irradiation program can be found in Refs. [6,11]. The beryllium pebbles were crushed to nanosized powder and investigated by means of TEM after deposition on a carbon net.…”

“…High-temperature neutron irradiation experiments of beryllium materials and subsequent investigations of their microstructure by transmission electron microscopy (TEM) have been carried out already [3][4][5][6]. This study focuses on analysis chemical composition and spatial distribution of impurity particles and their possible influence on the formation of fracture surfaces or crack propagation in beryllium.…”

Tritium release from highly neutron irradiated constrained and unconstrained beryllium pebbles

“…For the same reason, the gas pipes in the manifold are heated to 573 K during the TD tests. During the TD tests, the helium atoms (mainly isotope 4 He) escaping from gas bubbles [6] at a given temperature diffuse through the matrix and reach the external surface where they freely leave the pebble. It is assumed that the main part of tritium exists in bubbles in molecular form [7].…”

Microstructure of out-of-pile annealed neutron irradiated beryllium studied by X-ray tomography

“…At temperatures below $400°C only very small (7-8 nm) facetted bubbles (if any) can be observed in a transmission electron microscope. At higher temperatures, the size of helium bubbles increases with the irradiation temperature, reaching, e.g., 140 nm at 695°C [1]. Interconnected observed on the grain boundaries and sometimes within the grain body.…”