Low volatile fission-product release and fuel volatilization during severe reactor accident conditions

Implementation of A Gibbs Energy Minimizer In A Fission-Product Release Computer Program

“…In both the old (SOURCE IST 2.0P11) model from Corse [12][13][14] and in SC11 chemical equilibrium is assumed to exist at the fuel surface. The target scenarios for the computer programs are those with higher fuel temperatures than normal operating conditions and it is likely that kinetic limits are not as prevalent as at lower temperatures.…”

“…In the 1997 model by Corse [12][13][14], that composition was fixed by two user-specified factors and by the pre-calculated composition of CANDU fuel at a burnup 2 of 100 MW·h·kg -1 . The user-specified equilibrium ratio of molar hydrogen, H 2 (g), to steam, H 2 O(g), fixed the initial oxygen potential of the system.…”

“…SOURCE 2.0 contains models for the following physical phenomena: actinide fission, transmutation and decay [4][5][6], fission-product diffusion within fuel grains [7][8][9][10] coupled to fission-product yield, decay and transmutation; equi-axed and columnar grain growth, grain-boundary sweeping, grain-boundary bubble growth and interlinkage [11]; fission-product vaporization from the fuel surface [12][13][14]; and grain-boundary separation. [12][13][14]. That model was based on lookup tables generated with the FACT (Facility for the Analysis of Chemical Thermodynamics) computer program [15][16][17] and was tractable on computers of that day.…”

Assessment of the models of urania fuel oxidation in steam-rich atmosphere

“…They were derived from the same source [14], with the differences originating from the details in fitting Gibbs energy for steam dissociation, where, in [6], the thermodynamical data from [15] were used (as quoted in [16]), leading only to small differences in the calculated values of K as shown in Table 2.…”

Thermodynamic considerations and prediction of the primary coolant activity of 99Tc

“…This analysis was performed on the basis of a Bruce fuel channel. In particular, the analysis considered the fission product inventory in the fuel bundles of the channel (i.e., as estimated with the ORIGEN code at a fuel burnup of 100 MWh/kgU), [23] and the relative volumes of the fuel bundles to free space in the channel for the atmospheric constituent. This approach essentially assumes an unlimited supply of steam and water into the fuel-to-clad gap where there is an open system with the possibility of a continual replenishment of steam/water from the primary coolant into the failed rod.…”