A New Mechanistic and Engineering Fission Gas Release Model for a Uranium Dioxide Fuel

A mechanistic and engineering fission gas release model (MEGA) for uranium dioxide (UO2) fuel was developed. It was based upon the diffusional release of fission gases from inside the grain to the grain boundary and the release of fission gases from the grain boundary to the external surface by the interconnection of the fission gas bubbles in the grain boundary. The capability of the MEGA model was validated by a comparison with the fission gas release data base and the sensitivity analyses of the parameters. It was found that the MEGA model correctly predicts the fission gas release in the broad range of fuel burnups up to 98MWd/kgU. Especially, the enhancement of fission gas release in a high-burnup fuel, and the reduction of fission gas release at a high burnup by increasing the UO2 grain size were found to be correctly predicted by the MEGA model without using any artificial factor.

[1]  Kazuhiro Nogita,et al.  Formation and growth of intragranular fission gas bubbles in UO2 fuels with burnup of 6–83 GWd/t , 1993 .

[2]  D. Baron,et al.  High burn-up rim structure: evidences that xenon-depletion, pore formation and grain subdivision start at different local burn-ups , 1998 .

[3]  F. E. Panisko,et al.  ANS54: a computer subroutine for predicting fission gas release , 1979 .

[4]  P. Menut,et al.  The public domain database on nuclear fuel performance experiments (IFPE) for the purpose of code development and validation , 2000 .

[5]  R. Manzel,et al.  EPMA and SEM of fuel samples from PWR rods with an average burn-up of around 100 MWd/kgHM , 2002 .

[6]  R. J. White,et al.  A new fission-gas release model , 1983 .

[7]  Brent J. Lewis,et al.  Fission product release mechanisms during reactor accident conditions , 1999 .

[8]  Donald R. Olander,et al.  Fundamental aspects of nuclear reactor fuel elements: solutions to problems , 1976 .

[9]  F. A. Johnson,et al.  The diffusion coefficients of gaseous and volatile species during the irradiation of uranium dioxide , 1982 .

[10]  A. Massih.  Percolation model for bubble interlinkage in ceramic nuclear fuels , 1983 .

[11]  F. Nagase,et al.  Behavior of 60 to 78MWd/kgU PWR Fuels under Reactivity-Initiated Accident Conditions , 2006 .

[12]  Y. Jung,et al.  An attempt to explain the high burnup structure formation mechanism in UO2 fuel , 2000 .

[13]  J. Rest,et al.  The effect of irradiation-induced gas-atom re-solution on grain-boundary bubble growth , 2003 .

[14]  K. Lassmann,et al.  Modelling the High Burnup UO2 Structure in LWR Fuel , 1995 .

[15]  M. V. Speight,et al.  A Calculation on the Migration of Fission Gas in Material Exhibiting Precipitation and Re-solution of Gas Atoms Under Irradiation , 1969 .

[16]  H. Matzke,et al.  A Pragmatic Approach to Modelling Thermal Conductivity of Irradiated UO2 Fuel. Review and Recommendations , 1996 .

[17]  Charles F. Bonilla,et al.  Fundamental Aspects of Nuclear Reactor Fuel Elements , 1978 .