| NUKLEONIKA 2013, 58(2):295-300
DIFFUSION OF HELIUM IN THE PERFECT URANIUM AND THORIUM DIOXIDE SINGLE CRYSTALSLudwik Dąbrowski, Marcin Szuta National Centre for Nuclear Research (NCBJ), 7 Andrzeja Sołtana Str., 05-400 Otwock/Świerk, Poland We present quantum-mechanical evaluation of helium diffusion coefficient in the crystalline UO2 and ThO2. Parameters assignment of Schrödinger’s equation were done using the crystal field potentials which were obtained applying the density functional theory (DFT). “Ab initio” calculations were performed using the Wien2k program package. To compute the unit cell parameters the 13 atom super-cell was chosen. Applying two-site model we evaluated the time for an over-barrier jump and diffusion of interstitial He. The obtained values for diffusion coefficient are compared with the experimentally obtained values and with the theoretical values of other authors. In addition, it is simultaneously shown that helium diffusion in these materials is a quantum diffusion. Close X |