The re-solution of gas atoms from bubbles during the irradiation of UO2

Mechanistic modelling of urania fuel evolution and fission product migration during irradiation and heating

“…The code predicts a complete suppression of the intra-granular bubble nucleation at T > 2273 K, in a qualitative agreement with observations of [20], and a significant delay in the onset of the bubble formation at low temperatures T < 973 K, as observed in tests [21], owing to the thermal re-solution effect presented in Eq. (4) by the term k gb ðC g À C eq g ÞC b (see [1]).…”

Fission product release in the first two PHEBUS tests FPT0 and FPT1

“…The gas behaviour is still described by inter-granular processes but intra-granular gas behaviour becomes important. In the case of FPT1 and depending on fission rate, some irradiation re-solution of gas atoms from grain bubbles occurred (Nelson, 1969;Turnbull and Cornell, 1970), leading to their possible diffusion as single atoms to grain boundaries and further release in open porosities. Nevertheless, one must also consider the behaviour of grain bubbles and their interactions with point and extended defects.…”

Predicted mechanisms for radiation enhanced helium resolution in uranium dioxide

“…The resolution of helium may occur from thermal effects, although at normal fuel operating and storage temperatures this is thought to make a small contribution to the total resolution rate [19,13]. Alternatively gas may reenter the lattice through radiation-enhanced resolution [20][21][22]. In this second process helium atoms are returned to the lattice by the interaction of the bubbles with energetic recoil cascades initiated by fission or a-decay events within the nuclear fuel.…”